Bibliography Jean-Paul Linnartz, 2006

	[1] 	van Rijnsoever, B. J., Lenoir, P., and Linnartz, J. P. M. G., "Interoperable protection for digital multimedia content," Journal of Vlsi Signal Processing Systems for Signal Image and Video Technology, vol. 34, no. 1-2, pp. 167-179, 2003.
Keywords: OPIMA,interoperability,architecture,content-protection,conditional-access,DRM,copy-protection
Abstract: Interoperability between systems for secure delivery of content (audio and video) over the Internet or via digital television broadcasting is still hampered by the lack of interoperability among proprietary content protection systems. The OPIMA (Open Platform Initiative for Multimedia Access) specification offers a generic solution for multimedia terminals, in which the end-user's terminal is adapted to a content protection system by downloading a corresponding plug-in. This paper describes the OPIMA solution and shows how it can be applied
	[2] 	Willems, F., Kalker, T., Goseling, J., and Linnartz, J., "On the capacity of a biometrical identification system," Proceedings 2003 IEEE International Symposium on Information Theory.ISIT 2003 (Cat.No.03CH37432), pp. 82, 2003.
Abstract: We investigate fundamental properties of biometrical identification systems. We focus on the capacity, i.e. a measure for the number of individuals that can be reliably identified. It can be expressed using standard information-theoretical concepts
	[3] 	Linnartz, J. and Tuyls, P., "New shielding functions to enhance privacy and prevent misuse of biometric templates," Audio- and Video-Based Biometric Person Authentication.4th International Conference, AVBPA 2003.Proceedings (Lecture Notes in Computer Science Vol.2688), pp. 393-402, 2003.
Abstract: In biometrics, a human being needs to be identified based on some characteristic physiological parameters. Often this recognition is part of some security system. Secure storage of reference data (i.e., user templates) of individuals is a key concern. It is undesirable that a dishonest verifier can misuse parameters that he obtains before or during a recognition process. We propose a method that allows a verifier to check the authenticity of the prover in a way that the verifier does not learn any information about the biometrics of the prover, unless the prover willingly releases these parameters. To this end, we introduce the concept of a delta-contracting and epsilon-revealing function which executes preprocessing in the biometric authentication scheme. It is believed that this concept can become a building block of a public infrastructure for biometric authentication that nonetheless preserves privacy of the participants
	[4] 	Tomasin, S., Gorokbov, A., Haibing, Y., and Linnartz, J., "Reduced complexity Doppler compensation for mobile DVB-T," 13th IEEE International Symposium on Personal Indoor and Mobile Radio Communications.PIMRC 2002.Proceedings (Cat.No.02TH8637), pp. 2077-2081, 2002.
Abstract: The reception of the DVB-T signal on a mobile equipment is strongly affected by Doppler spread. Most of the current proposals require the use of two or more antennas at the receiver and a computationally expensive signal processing. In this paper for a DVB-T receiver with a single antenna we propose new schemes based on the interference cancellation principle. With respect to previously studied techniques, our solution is able to deliver DVB-T services at higher speeds, while a more flexible architecture allows a wider range of trade-off between complexity and performance. In order to improve the performance in terms of maximum achievable speed, an iterative scheme is proposed which performs both the interference cancellation and the channel estimation. A decoding and re-encoding of the inner convolutional code is inserted into the iteration process in order to boost the performance. Moreover, by applying the interference cancellation principle also for the estimation of the channel parameters, we obtain a scheme with a reasonable complexity for the DVB system. Simulation results for various DVB-T modes, constellations and code rates show that the proposed schemes allow the correct reception of DVB-T for moderate and high speeds
	[5] 	Gorokhov, A. and Linnartz, J., "Robust OFDM receivers for dispersive time varying channels: equalisation and channel acquisition," 2002 IEEE International Conference on Communications.Conference Proceedings.ICC 2002 (Cat.No.02CH37333), pp. 470-474, 2002.
Abstract: In orthogonal frequency division multiplexing (OFDM), time variations of a fading multipath environment lead to a loss of orthogonality between the subcarriers and thereby limit the achievable throughput. This paper suggests a general framework for a controlled removal of intercarrier interference (ICI) and channel acquisition. The core idea behind our method is to use a finite Taylor expansion for the time-varying frequency response along with the known statistical properties of mobile radio channels. Channel acquisition and ICI removal are accomplished in the frequency domain and allow for any desired tradeoff between the residual ICI level, the required training for channel acquisition and processing complexity
	[6] 	Oostveen, J., Kalker, T., and Linnartz, J., "Optimal detection of multiplicative watermarks," Signal Processing X Theories and Applications.Proceedings of EUSIPCO 2000.Tenth European Signal Processing Conference, pp. 1665-1668, 2000.
Abstract: We derive a watermark detector for images which are watermarked in a multiplicative way. Under the assumptions that the watermark coefficients are a known, binary valued sequence and that the original image coefficients are an iid random sequence from a Weibull distribution, we show that this watermark should be detected by raising the observations to the power beta before correlating them with the watermark (here beta is the parameter in the exponent of the Weibull probability density function). The approach is based on maximum-likelihood estimation of the embedding strength of the watermark. The result is illustrated by experiments and an extension to Gaussian distributed data is discussed
	[7] 	Linnartz, J. and Gorokhov, A., "New equalization approach for OFDM over dispersive and rapidly time varying channel," 11th IEEE International Symposium on Personal Indoor and Mobile Radio Communications.PIMRC 2000.Proceedings (Cat.No.00TH8525), pp. 1375-1379, 2000.
Abstract: The paper proposes and analyses a new receiver structure to mitigate the effect of Doppler on the reception of OFDM signals. A discrete-frequency channel representation is developed for the link between the input of the transmit I-FFT and the output of the receive FFT. It is based on a Taylor expansion of the time variations of the received subcarrier amplitudes. The model realistically addresses the correlation of fading at neighboring subcarriers. We study a new type of receiver which estimates not only amplitudes but also derivatives of subcarriers amplitudes. An adaptive MMSE filter is proposed to cancel the intercarrier interference (ICI) resulting from Doppler. This results in a substantial improvement of the link performance
	[8] 	van Rijnsoever, B. and Linnartz, J., "Interoperable content protection for digital TV," 2000 IEEE International Conference on Multimedia and Expo.ICME2000.Proceedings.Latest Advances in the Fast Changing World of Multimedia (Cat.No.00TH8532), pp. 1407-1410, 2000.
Abstract: Interoperability in digital TV is still hampered by proprietary content protection systems. The OPIMA specification offers a generic solution for multimedia terminals, in which the end-user's terminal is adapted to a content protection system by downloading a corresponding plug-in. This paper describes the OPIMA solution and shows how it can be applied to digital TV
	[9] 	Linnartz, J., Talstra, J., Kalker, T., and Maes, M., "System aspects of copy management for digital video," 2000 IEEE International Conference on Multimedia and Expo.ICME2000.Proceedings.Latest Advances in the Fast Changing World of Multimedia (Cat.No.00TH8532), pp. 203-206, 2000.
Abstract: The paper reviews basic principles of copy protection for digital video. We distinguish between the role of cryptography and embedded signaling, as seen by standardization bodies such as the DVD Copy Protection Technical Working Group (CPTWG). We identify several issues that are unresolved and/or currently under discussion. In particular, we elaborate on play control, copy generation control, and unique identification of digital storage media
	[10] 	Linnartz, J., "Partial correlations and cyclic prefixes in direct sequence spread spectrum," Gateway to 21st Century Communications Village.VTC 1999-Fall.IEEE VTS 50th Vehicular Technology Conference (Cat.No.99CH36324), pp. 2696-2700, 1999.
Abstract: The RAKE receiver for direct sequence (DS) spread spectrum can separate energy received over multiple propagation paths with different time delays. Each finger in the RAKE sees signals with a specific time delay, but it also sees some unwanted residual crosstalk from signals over differently delayed paths. If bit transitions occur in delayed reflection, the crosstalk between two fingers in the RAKE detector is determined by two partial correlation functions, which exhibit substantially inferior properties than can be achieved for the full (or periodic) autocorrelation function. The aim of this paper is twofold: (1) to propose a new model to estimate the variance of partial correlations; (2) to show that cyclic prefixes improve the BER experienced when DS is transmitted over a dispersive multipath channel
	[11] 	Linnartz, J., Kalker, T., and Haitsma, J., "Detecting electronic watermarks in digital video," 1999 IEEE International Conference on Acoustics, Speech, and Signal Processing.Proceedings.ICASSP99 (Cat.No.99CH36258), pp. 2071-2074, 1999.
Abstract: Electronic watermarking is an active area of research with many applications being foreseen. Watermarks may become an essential tool for copy management in future consumer electronic or PC devices. With simple circuits, detection of watermarks after noise addition, MPEG compression, D/A conversion, pixel shifts appears feasible, but detection after transformations, such as cropping and stretching, remains a challenge. We propose a model to evaluate the effect of scaling on the detector reliability and verify it with experiments
	[12] 	Linnartz, J., Kalker, T., and Depovere, G., "Modelling the false alarm and missed detection rate for electronic watermarks," Information Hiding.Second International Workshop, IH'98.Proceedings, pp. 329-343, 1998.
Abstract: Theoretical modeling of watermarks allow prediction of the detector reliability and facilitates the development of more reliable systems. In particular, mathematical evaluation is relevant to estimating the rate at which "false alarms" occur. The probability of incorrect detection (missed detection or false alarm) is expressed in terms of the watermark-energy-to-image-luminance-variance ratio. We present some counterintuitive results which show for instance that the reliability of detection significantly depends on spatial correlation in the watermark. Moreover we find that a small but uncompensated random DC component in the watermark can have a significant effect on the reliability
	[13] 	Linnartz, J. and Van Dijk, M., "Analysis of the sensitivity attack against electronic watermarks in images," Information Hiding.Second International Workshop, IH'98.Proceedings, pp. 258-272, 1998.
Abstract: In some applications of electronic watermarks, the device that detects whether content contains a watermark or not is in the public domain. Attackers can misuse such a detector as an oracle that reveals up to one bit of information about the watermark in each experiment. An information-theoretical analysis of the information leakage is provided, and a method is proposed to reduce the information leakage by orders of magnitude
	[14] 	Depovere, G., Kalker, T., and Linnartz, J., "Improved watermark detection reliability using filtering before correlation," Proceedings 1998 International Conference on Image Processing.ICIP98 (Cat.No.98CB36269), pp. 430-434, 1998.
Abstract: A digital watermark is a perceptually unobtrusive signal embedded in some multimedia asset carrying additional information: e.g. copyright information of a video clip. For nearly all watermarking schemes published so far, detection is based on some form of correlation. We show that the detection reliability can be significantly improved by applying filtering prior to correlation. This improvement is analysed using a theoretical model based on statistical communication and detection theory. Finally, the improvements predicted by the theory are verified in a number of experiments
	[15] 	Kalker, T., Linnartz, J., and Van Dijk, M., "Watermark estimation through detector analysis," Proceedings 1998 International Conference on Image Processing.ICIP98 (Cat.No.98CB36269), pp. 425-429, 1998.
Abstract: A watermark is a perceptually unobtrusive signal embedded in an image, an audio or video clip, or any other other multimedia asset. Its purpose is to be a label which is holographically attached to the content. Moreover, it can only be removed by malicious and deliberate attacks (without a great loss of content quality) if some secret parameter K is known. In contrast, a watermark should be readily detectable by electronic means. This implies that electronic watermark detection is only feasible if the watermark detector is aware of the secret K. In many watermarking business scenarios the watermark detector will be available to the public as a black box D. The following question is therefore justified: can the secret K be deduced from the operation of the black box D? And if yes, what is the complexity of this process? We address these questions for a large class of watermarking schemes
	[16] 	Linnartz, J., "The "ticket" concept for copy control based on embedded signalling," Computer Security - ESORICS 98.5th European Symposium on Research in Computer Security.Proceedings, pp. 257-274, 1998.
Abstract: This application-oriented paper discusses the use of electronic watermarks (also called embedded signaling) for copy control. Playback control and copy-once are described. The ticket concept is presented to provide these functionalities. Although the ticket shows similarities with a digital signature, there are essential differences. For instance, the ticket allows typical modifications of the content, which are common practice in transmission, storage and presentation of video. The concept is part of a proposal under investigation for standardization of DVD/CPTWG copy control. This paper also compares the ticket concept with other solutions, such as embedding a secondary mark at the recorder and using a signature scheme
	[17] 	Linnartz, J. and Talstra, J., "MPEG PTY-Marks: cheap detection of embedded copyright data in DVD-video," Computer Security - ESORICS 98.5th European Symposium on Research in Computer Security.Proceedings, pp. 221-240, 1998.
Abstract: We propose a method to watermark digital video content in such a way that detection in consumer electronics equipment is possible with very little hardware (a few thousand gates). The method proposes to modify the MPEG encoding procedure to choose the so-called Picture Type of video-frames not from a regular sequence but according to a message one would like to transmit. Removal of this embedded message, the PTY-Mark, from the resulting MPEG-stream without jeopardizing video quality is only possible after a complete MPEG decoding and re-encoding cycle. We investigate the modifications to current MPEG encoders which are necessary to accommodate these PTY-Marks. Based on tests we comment on their feasibility. Detection of watermarks without secrets is very reminiscent of "public-key" cryptography. We discuss this relationship by contrasting PTY-Marks with pixel-watermarking
	[18] 	Hollmann, H., Linnartz, J., van Lint, J., Baggen, C., and Tolhuizen, L., "Protection of software algorithms executed on secure modules," Future Generation Computer Systems, vol. 13, no. 1, pp. 55-63, 1997.
Abstract: Loop structures in software code may reveal essential information about implemented algorithms and their parameters, even if the observer has no knowledge about which instructions are executed. Regular patterns can for instance be observed in power consumption, instruction fetches in external memory, or radiated EM energy. This paper addresses the use of dummy operations to obscure the details of the algorithm executed by the processor. We show that for a particular class of dummy insertion strategies, a Viterbi decoder can fairly reliably distinguish dummy fetches from real instruction fetches. In the second part of this paper, we study strategies to choose dummy fetches from a more general model. For certain situations, the optimum protection strategy appears to be deterministic (as opposed to random). Moreover, we show that in such a case, it is fundamentally not possible to enhance the security of the implementation by keeping the strategy for generating dummy fetches secret to the attacker
	[19] 	Tank, T. and Linnartz, J., "Vehicle-to-vehicle communications for AVCS platooning," IEEE Transactions on Vehicular Technology, vol. 46, no. 2, pp. 528-536, 1997.
Abstract: Vehicle-to-vehicle radio links suffer from multipath fading and interference from other vehicles. We discuss the impact of these effects on communication networks supporting an intelligent transportation system (ITS), in particular, automated vehicle control systems (AVCSs). A statistical model for this channel is considered, and the performance of the network involving many links is evaluated. We compare the performance of time division multiple access (TDMA), direct-sequence code division multiple access (DS-CDMA), and frequency hopping with TDMA in this environment. The reliability of the radio link is investigated by specifying the radio spectrum occupation for a given required reliability of the radio link
	[20] 	Tsybakov, B., Likhanov, N., and Linnartz, J., "Intercell and intracell collision resolution in wireless packet data networks," IWMC '96, International Workshop on Mobile Communications, pp. 128-133, 1996.
Abstract: We address a new medium access algorithm that allows many wireless terminals to access a network of base stations on a cellular grid. Our frame algorithm allows extremely dense frequency reuse as it not only resolves message collisions within a cell but also controls mutual interference among adjacent cells. We compute throughput and packet delays considering path loss and Rayleigh-fading
	[21] 	Wang, R. and Linnartz, J., "Design of a frequency hopping spread spectrum communication system for an automated highway system," Conference Record of The Twenty-Ninth Asilomar Conference on Signals, Systems and Computers, pp. 265-269, 1996.
Abstract: Frequency hopping spread spectrum communication techniques are investigated in the context of the PATH automated highway system project, where reliable communication links are needed from vehicle to vehicle. Multiple access interference and Ricean multipath fading are considered. Performance measures studied include the probability of packet error and the probability that no message is received in a certain time window
	[22] 	van den Broek, C. and Linnartz, J., "A simulation study of space and time reservation multiple access," Sixth IEEE International Symposium on Personal, Indoor and Mobile Radio Communications.PIMRC'95.Wireless: Merging onto the Information Superhighway (Cat.No.95TH8135) , pp. 527-531, 1995.
Abstract: The paper introduces a new protocol for wireless cellular networks by combining a time reservation scheme with a dynamic space reservation scheme. The proposed new protocol, known as the space and time reservation multiple access (STRMA) protocol, does not use a fixed reuse pattern but allows a dynamic reservation of bandwidth in both time and space. The performance of this protocol found by simulation is compared with the performance of a cellular network that uses PRMA with a fixed frequency reuse pattern. It is found that for homogenous traffic STRMA offers improved performance over a wide range of traffic loads. For inhomogeneous traffic the improvement is even more pronounced
	[23] 	Fedortsov, S. and Linnartz, J., "One dimensional cellular network with "spatial-ALOHA" protocol," Sixth IEEE International Symposium on Personal, Indoor and Mobile Radio Communications.PIMRC'95.Wireless: Merging onto the Information Superhighway (Cat.No.95TH8135), pp. 886-890, 1995.
Abstract: We address the transmission of data packets from base stations to mobile terminals in a one-dimensional cellular network. The probability that a data packet successfully arrives at the destined mobile terminal highly depends on the activity of nearby co-channel base stations. Motivated by favorable results from earlier studies we consider a network in which all base stations use the same radio channel. Packets lost because of mutual interference are retransmitted with a random backoff mechanism. Recursive arguments are applied for the calculation of the mean time necessary for a base station to deliver the packet, provided that in an initial state all stations have packets to transmit. The average delivery time, maximized over all base station locations, is also analyzed. The relations obtained give some further insight into the behavior of a (highway) cellular data network
	[24] 	Vvedenskaya, N. and Linnartz, J., "Single-frequency packet network using stack algorithm and multiple base stations," Broadband Communications.Networks, Services, Applications, Future Directions.1996 International Zurich Seminar on Digital Communications, IZS '96.Proceedings, pp. 289-298, 1996.
Abstract: This paper evaluates a new method to combine contiguous frequency reuse with random access in wireless packet-switched networks. We consider a radio network with two base stations receiving packets transmitted by a large population of mobile users. Both stations share the same channel and therefore transmissions to one base station in one cell interface with transmissions to the other base station in the other cell. A simulation of a two-cell system is performed, to study the interaction of retransmission traffic in two cells. To consider the performance of such system analytically, we model a one-cell system with time-varying channel properties: if only one station is receiving messages from its cell, the channel is assumed to be in "good state"; if terminals in both cells are busy the channels are assumed to be in "bad state". For conflict resolution, the stack-algorithm is used. The packet delay is calculated. Our results confirm that in wireless packet networks, it is advantageous to allow neighboring cells to share the same channel
	[25] 	Tank, T. and Linnartz, J., "Statistical characterization of Rician multipath effects in a mobile-to-mobile communication channel," International Journal of Wireless Information Networks, vol. 2, no. 1, pp. 17-26, 1995.
Abstract: A statistical model is developed for a narrowband mobile-to-mobile channel taking into consideration Rician scattering near receiving and transmitting antennas both individually and concomitantly. From the proposed channel model we obtain the probability density function of the received signal envelope, the time correlation function and RF spectrum of the received signal, and level crossing rates and average fade durations. We briefly discuss the impact of these parameters on communication networks supporting an intelligent vehicle highway system (IVHS)
	[26] 	Yee, N. and Linnartz, J., "Wiener filtering of multi-carrier CDMA in Rayleigh fading channel," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 1344-1347, 1994.
Abstract: Analyzes the application of Wiener filtering to the detection of multi-carrier code division multiple access (MC-CDMA) signals. Simulation results are included to test the validity and accuracy of the analytical results
	[27] 	Diesta, R. and Linnartz, J., "Multiple access and spatial collision resolution for IVHS packet radio networks," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 1260-1263, 1994.
Abstract: The spectrum efficiency of cellular radio data networks is maximized by increasing the cell throughput and decreasing the cluster sizes. However, smaller cluster sizes lead to higher cochannel interference and hence lower throughput. A multiple access and collision resolution scheme that accounts for the spatial aspects of cochannel interference is introduced and analyzed for roadside base station to vehicle packet communications in intelligent vehicle highway systems (IVHS). In a wireless network with base stations having full knowledge of neighboring station activity, cochannel interference and destructive collisions are diminished by using discontinuous transmissions and coordination: a base station is silenced (or power-controlled) by a neighboring station in order to improve the latter's chance of successful transmission and decrease retransmission attempts. Interaction among base stations makes efficient use of channel resources for both low- and high-intensity traffic
	[28] 	Linnartz, J., "Packet-switched cellular communication architecture for IVHS using a single radio channel," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 1222-1226, 1994.
Abstract: This paper proposes a radio architecture that offers two-way transmission services essential to intelligent vehicle highway systems (IVHS) using only a single (30 kHz) radio channel. Within this bandwidth multiple communication services can be supported, including datacasting, packet switched transmission to and from vehicles, collection of traffic data from probe vehicles and transmission of emergency messages. The design is based on theoretical investigations reported at PIMRC '93 and VTC '94 on packet-switched downlink transmissions and ALOHA random access for traffic reports from probe vehicles, respectively. These analyses revealed that contiguous frequency reuse gives optimum packet delay and highest spectrum efficiency. New results are included for datacasting messages to groups of vehicles
	[29] 	Vvdenskaya, N. and Linnartz, J., "Effect of CDMA transmission on performance of wireless networks with stack algorithm for collision resolution," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 1129-1132, 1994.
Abstract: This paper evaluates the performance of a packet radio network employing code division multiple access and a stack algorithm to resolve message collisions. We investigate the effects of bandspreading assuming a fixed total system bandwidth. Although bandspreading with perfectly orthogonal signals enhances system capacity, it does not resolve the instability of ALOHA random access unless special measures are taken to control retransmission traffic. Using a stack algorithm, at small traffic loads the packet delay is minimized if no spreading is applied. At large traffic loads, perfect CDMA enhances performance, but for imperfect signal separation at the receiver, advantages of CDMA are lost. The capacity of the stack algorithm addressed here can be enhanced from 0.32 to at least 0.40 if a large spreading factor with perfect signal separation is employed
	[30] 	Couture, M. and Linnartz, J., "Improved channel modelling for performance analysis of a DS-CDMA link," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 705-710, 1994.
Abstract: The paper developed a refined model for DS spread spectrum transmission over a Rician fading channel. A prevalent model in previous papers has been to group all signals received other than the dominant LOS path as interference. A new approach is taken, whereby some components of the multipath are included in the desired signal. An expression for the local-mean BER is derived from this model, and an analysis of BER as a function of the number of users is performed
	[31] 	Diesta, R. and Linnartz, J., "Using Laplace transforms to compute performance of mobile radio links," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 301-305, 1994.
Abstract: This paper reviews progress in developing a mathematical framework to evaluate the performance of mobile radio links. It takes into account multi-ray multipath fading with Rician or Nakagami probability density, lognormal shadowing and path loss of wanted and interfering transmitters, additive white Gaussian noise, man-made burst noise and discontinuous transmission. The method uses Laplace transforms of the PDF of the power of each interfering signal. This method is computationally efficient and allows inclusion of a wide range of link aspects. We also show that, in contrast to common belief, it is not realistic to approximate the Rician fading of the wanted signal by a Nakagami model. New results are given for microcells along highways
	[32] 	Bar-Ness, Y., Linnartz, J., and Xiangqun, L., "Synchronous multi-user multi-carrier CDMA communication system with decorrelating interference canceler," Wireless Networks - Catching the Mobile Future - 5th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'94), and ICCC Regional Meeting on Wireless Computer Networks (WCN), pp. 184-188, 1994.
Abstract: Multi-carrier (MC) multi-user CDMA is a new transmission method in which every user bit is sent simultaneously over multiple subcarriers (or multiple tones), each of which has a time-constant 0 or pi phase offset. The offsets corresponding to each user form a unique code signature sequence, orthogonal to those of any other user, or pseudo orthogonal as with Gold codes or Kessami code sequences. We address a moderately dispersive channel in which each user-subcarrier channel has a different random amplitude and phase. We estimate the performance of a receiver matched to such a multicarrier, multi-user scheme. Then we implement a decorrelating interference canceler at the output and examine its effect on performance
	[33] 	Linnartz, J., "Slotted ALOHA mobile network with vertical array antenna diversity," 1994 IEEE GLOBECOM.Communications: The Global Bridge.Conference Record (Cat.No.94CH34025), pp. 79-82, 1994.
Abstract: In mobile radio networks, receiver capture is known to enhance the performance of the slotted ALOHA random access protocol substantially. The efficiency of narrowband slotted ALOHA radio networks can be further enhanced by using sector antennas. The paper investigates the effect of partially overlapping, realistic antenna patterns which gives highly correlated received power levels at different receiver branches. The author proposes a method for computing the joint throughput from two base station antennas. The a posteriori information provided by the event of one message capturing one antenna is used to find conditional probabilities of capturing the other antennas. Any overlap in the antenna patterns decreases the throughput, but transmissions from the overlap area face a larger probability of capture than signals from directions in which only one antenna has significant gain
	[34] 	Diesta, R. and Linnartz, J., "Spatial collision resolution for packet-switched multiple-access wireless networks," Conference Record of the Twenty-Eighth Asilomar Conference on Signals, Systems and Computers (Cat.No.94CH34546), pp. 234-237, 1994.
Abstract: A collision resolution scheme that accounts for the spatial aspects of co-channel interference is analyzed for multiple access packet communications with application in intelligent vehicle highway systems (IVHS). In wireless networks with interacting base stations, co-channel interference and collisions are diminished by using discontinuous transmissions and coordination: a base station is silenced (or power-controlled) by a neighboring station in order to improve the latter's chance of successful transmission and decrease retransmission attempts. The performance of this spatial collision resolution scheme is studied with a priori knowledge packet capture probabilities
	[35] 	Davis, J. and Linnartz, J., "Vehicle to vehicle RF propagation measurements," Conference Record of the Twenty-Eighth Asilomar Conference on Signals, Systems and Computers (Cat.No.94CH34546) , pp. 470-474, 1994.
Abstract: We present results from vehicle to vehicle RF propagation measurements centered at 900 MHz. We focus on determining delay spread probability distribution parameters (in particular the Rician K factor) and path loss rates. Our results are discussed with implications for the use of RF communication between automobiles in Intelligent Vehicle Highway Systems (IVHS). Our paper consists of a description of the IVHS concept along with a brief overview of wireless propagation theory. We then discuss our measured parameters with respect to implementing an RF transmission system between vehicles
	[36] 	Linnartz, J., "On the performance of packet-switched cellular networks for wireless data communications," Wireless Networks, vol. 1, no. 2, pp. 129-138, 1995.
Abstract: Cellular frequency reuse is known to be an efficient method to allow many wireless telephone subscribers to share the same frequency band. However, for wireless data and multi-media communications optimum cell layouts differ essentially from typical solutions for telephone systems. The author argues that wireless radio systems for bursty message traffic preferably use the entire bandwidth in each cell. Packet queueing delays are derived for a network with multipath fading channels, shadowing, path loss and discontinuously transmitting base stations. Interference between cells can be reduced by appropriately scheduling transmissions or by `spatial collision resolution'
	[37] 	Linnartz, J., Yun, L., and Couture, M., "Multi-user and self interference effects in a QPSK DS-CDMA downlink with a Ricean dispersive channel," Wireless Personal Communications, vol. 1, no. 2, pp. 95-102, 1994.
Abstract: The paper derives the BER in synchronous (downlink) indoor direct-sequence code division multiple access (DS-CDMA) transmission over a Ricean multipath channel with a non-uniform delay profile. Computational results show that the performance is much better than that predicted by models which assume that all resolvable paths have independent identically distributed (i.i.d.) power
	[38] 	Hwa, J. K. and Linnartz, J., "Virtual cellular network: a new wireless communications architecture with multiple access ports," VTC 1994.`Creating Tomorrow's Mobile Systems'.1994 IEEE 44th Vehicular Technology Conference (Cat.No.94CH3438-9), pp. 1055-1059, 1994.
Abstract: A new cellular communication architecture, called a `virtual cellular network' (VCN) is proposed and its performance is investigated in terms of probability of capture, throughput and delay. A VCN does not use a conventional cellular frequency reuse concept. In a VCN, each terminal sends packets using the entire system bandwidth while any nearby port can pick up the signal. Then, the ports relay the packets to the port server (PS) over a fixed (wired) network. This simplifies the functions of a port, and the placement of ports will be easier than that in a conventional cellular network. Both the present analysis and simulation show that despite its simplicity this network has a larger user capacity than conventional cellular reuse patterns
	[39] 	Yee, N. and Linnartz, J., "BER of multi-carrier CDMA in an indoor Rician fading channel," Conference Record of The Twenty-Seventh Asilomar Conference on Signals, Systems and Computers (Cat.No.93CH3312-6), pp. 426-430, 1993.
Abstract: The paper analyzes a novel digital modulation technique called multi-carrier code division multiple access (MC-CDMA) in which data symbols are transmitted at multiple subcarriers where each subcarrier is modulated by a 1 or -1 based on a spreading code. Analytical results are presented on the performance of this modulation scheme in the downlink of an indoor wireless Rician fading channel. In addition, the performance of a controlled equalization technique that attempts to restore the orthogonality between users is evaluated
	[40] 	Yee, N. and Linnartz, J., "Controlled equalization of multi-carrier CDMA in an indoor Rician fading channel," VTC 1994.`Creating Tomorrow's Mobile Systems'.1994 IEEE 44th Vehicular Technology Conference (Cat.No.94CH3438-9), pp. 1665-1669, 1994.
Abstract: In this paper, a novel digital modulation technique called Multi-Carrier Code Division Multiple Access (MC-CDMA) is analyzed. With MC-CDMA, each data symbol is transmitted at multiple subcarriers with each subcarrier modulated by "1" or "-1" based on a spreading code. Analytical results are presented on the performance of this modulation/multiple access scheme in the downlink of an indoor wireless Rician fading channel. The performance of a controlled equalization technique that attempts to restore the orthogonality between users is evaluated
	[41] 	Tank, T., Yee, N., and Linnartz, J., "Vehicle-to-vehicle communication for AVCS platooning," VTC 1994.`Creating Tomorrow's Mobile Systems'.1994 IEEE 44th Vehicular Technology Conference (Cat.No.94CH3438-9), pp. 448-451, 1994.
Abstract: Vehicle-to-vehicle radio links suffer from power variations, multipath fading and associated Doppler spreading in frequency, as well as interference from other vehicles. These effects are investigated in the context of an automated vehicle control systems (AVCS) employing vehicle platoons. A statistical model for the channel is considered and the performance of the network involving many links is evaluated. We compare the performance of time division multiple access (TDMA), direct sequence code division multiple access (DS-CDMA), and multi-carrier code division multiple access (MC-CDMA). Reliability of the radio link is investigated by specifying the radio spectrum occupation for a given required reliability of the radio link
	[42] 	Linnartz, J. and Westerman, M., "Monitoring a metropolitan freeway system using probe vehicles and random access radio channel," VTC 1994.`Creating Tomorrow's Mobile Systems'.1994 IEEE 44th Vehicular Technology Conference (Cat.No.94CH3438-9), pp. 410-414, 1994.
Abstract: The lack of proficient real time traffic monitoring systems is one of the major bottlenecks of Advanced Traveller Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS). The authors describe and analyze the performance of a method for collecting real-time traffic data from probe vehicles automatically sending traffic reports to one or more base stations, connected to a traffic center by a wired communications network. The results reveal that random access (ALOHA) transmission of traffic reports is a (spectrum) efficient, inexpensive and flexible method for collecting road traffic data and that this approach can provide reliable traffic monitoring. Not only highly accurate real time link travel times can be estimated, but also Automatic Incident Detection (AID) can be performed
	[43] 	Diesta, R., Eleazu, C., and Linnartz, J., "Packet-switched roadside base station to vehicle communication for intelligent vehicle/highway systems," VTC 1994.`Creating Tomorrow's Mobile Systems'.1994 IEEE 44th Vehicular Technology Conference (Cat.No.94CH3438-9), pp. 401-404, 1994.
Abstract: Optimum frequency reuse patterns for roadside base station to vehicle communications in intelligent vehicle/highway systems (IVHS) are determined based on optimal delay/throughput and packet erasure rates for BPSK transmission over narrowband dispersive Rician channel with ISI and (Rayleigh-faded) co-channel interference. For fixed cluster size and fixed total system bandwidth, a reuse pattern of 2 for continuously transmitting (hence interfering) base stations gives minimum average delay and maximum spectrum efficiency: this is a denser pattern than suggested for highway cellular telephony networks. Spectrum efficiency is enhanced by using a dynamic cluster size which depends on the distance from the base station, taking advantage of the IVHS environment where vehicle position may be known
	[44] 	Yun, L., Couture, M., Camagna, J., and Linnartz, J., "BER for QPSK DS-CDMA downlink in an indoor Ricean dispersive pico-cellular channel," Conference Record of The Twenty-Seventh Asilomar Conference on Signals, Systems and Computers (Cat.No.93CH3312-6), pp. 1417-1421, 1993.
Abstract: This paper derives the BER in synchronous (downlink) indoor direct-sequence CDMA transmission over a Ricean multipath channel with a non-uniform delay profile. Computational results will show that the performance is much better than that predicted by models which assume that all resolvable paths have i.i.d. power
	[45] 	Yee, N., Linnartz, J., and Fettweis, G., "Multi-carrier CDMA in indoor wireless radio networks," IEICE Transactions on Communications, vol. E77-B, no. 7, pp. 900-904, 1994.
Abstract: This paper examines a novel digital modulation/multiple access technique called multi-carrier code division multiple access (MC-CDMA) where each data symbol is transmitted at multiple narrowband subcarriers. Each subcarrier is encoded with a phase offset of 0 or pi based on a spreading code. Analytical results are presented on the performance of this modulation scheme in an indoor wireless multipath radio channel
	[46] 	Linnartz, J. and Westerman, M., "Performance analysis of road traffic data collection system," IEICE Transactions on Communications, vol. E77-B, no. 7, pp. 934-938, 1994.
Abstract: Advanced traveller information systems (ATIS) and advanced traffic management systems (ATMS) require real-time traffic data to observe and control the traffic flow. However, there is a lack of proficient traffic monitoring systems. One method to collect such data is using specially equipped vehicles, called `probes', to transmit experienced travel times to base stations which in turn are connected to a traffic control center. In this paper we analyse the performance of a radio network for collecting real-time traffic data from probes. The results reveal that random transmission of traffic reports is a (spectrum) efficient, inexpensive and flexible method for collecting road traffic data that can provide reliable traffic monitoring
	[47] 	Linnartz, J. and Vvdenskaya, N., "Optimising delay and throughput in packet-switched CDMA network with collision resolution using stack algorithm," Electronics Letters, vol. 30, no. 18, pp. 1470-1471, 1994.
Abstract: The authors address the effect of code division multiple access (CDMA) on the performance of wireless packet-switched networks. Although CDMA can enhance throughput, the delay at small traffic loads suffers from bandspreading. For imperfect signal separation at the receiver, performance benefits from CDMA may be lost. The capacity of the particular stack algorithm addressed for collision resolution can be enhanced from 0.32 to ~0.40 if a 10 dB spreading gain with perfect signal separation is employed
	[48] 	Linnartz, J., "Wireless communication improves traffic and transportation; New services require new cellular architecture," Revue HF, no. 1, pp. 27-35, 1994.
Abstract: Integration of multiple wireless communication services on a universal wireless radio infrastructure, suitable for any type of teletraffic and for any propagation environment, appears to be a non-trivial problem. The aspects of spatially reusing scarce radio spectrum and allowing multiple users to share the same bandwidth-time resources have mostly been addressed separately. Most existing wireless data and multi-media networks use a fixed cellular frequency re-use pattern, and within each cell a random-access scheme is operated independent from the teletraffic in other cells. Fixed cellular frequency reuse however appears far from optimum for packet-switched wireless data networks. Dynamic assignment of space-time-bandwidth resources in radio channels would be more efficient, but such techniques are not yet well developed. In this presentation, new schemes to integrate different types of teletraffic onto the same wireless channel are proposed, focussing on the communication requirements for intelligent vehicle highway systems
	[49] 	Kerkhoff, M., Linnartz, J., and Prasad, R., "Spectrum efficiency of packet switched data in mobile cellular networks," Archiv fur Elektronik und Uebertragungstechnik, vol. 48, no. 3, pp. 145-152, 1994.
Abstract: The performance of (downlink) packet switched data traffic in the mobile cellular network is analysed in terms of probability of successful packet reception and spectrum efficiency. In the analysis, effect of shadowing on both capture and non-fade duration is taken into account. Further, the authors have introduced a new definition of spectrum efficiency, which is defined here to be proportional to packet throughout. Numerical results are obtained for a channel bit rate of 16 kb/s and 256 kb/s, in case of a receiving mobile terminal traveling near the cell boundary and in case of a quasi-uniform offered traffic distribution. The results show that optimum cluster size (i.e for which special efficiency is maximal) reaches small values for the first case and approaches cluster size one for the second case
	[50] 	Linnartz, J., Awater, G., and Venema, R., "Throughput of inhibit sense multiple access with propagation delays," IEEE Transactions on Communications, vol. 42, no. 1, pp. 119-126, 1994.
Abstract: A large number of terminals transmitting data packets over a common radio channel to a central base station is studied. In inhibit sense multiple access (ISMA), the base station broadcasts a busy signal when an incoming packet is being received, to inhibit other terminals from colliding transmissions. This busy signal arrives at each terminal with a propagation delay, proportional to the distance between the base station and the terminal. This leads to unfairness in the probability of successfully transmitting a data packet, since nearby terminals have more up-to-date information on the actual channel status than remote terminals. This unfairness is additional to the advantage that nearby terminals have because of the capture effect, which is also considered. The paper applies nonstationary Poisson processes to describe the random arrivals of data packets at the central receiver. It is shown that the probability of a successful attempt to transmit a packet decreases, approximately linearly with the distance between the transmitter and the central receiver. The total throughput is also assessed, and it is found that the assumption of a fixed propagation delay adopted in CSMA studies by others gives too optimistic results for ISMA. Moreover, the analysis suggests a subtle change of the fixed delay approximation that enhances its accuracy, without adding complexity. The effect of propagation delays in random access radio networks are of increasing importance, since newly developed systems are designed to transmit with increasingly high bit rates
	[51] 	Linnartz, J., Groenewegen, M., and Prasad, R., "Performance analysis of a slotted-ALOHA network using error correction and error detection coding with BPSK modulation," PIMRC '92.The Third IEEE International Symposium on Personal, Indoor and Mobile Radio Communications Proceedings (Cat.No.92TH0488-7), pp. 282-286, 1992.
Abstract: The performance of a slotted ALOHA-network in a slow Rayleigh-fading channel for mobile data communications is investigated considering error correction and detection coding with binary phase shift keying (BPSK) modulation. The performance is measured in terms of receiver error probability and throughput. An enhanced performance is obtained by using error correction coding. In spite of the use of error correction coding, a packet can be in error, i.e. the receiver erroneously detects a codeword that none of the terminals transmitted. Bounded distance decoding can be used effectively to reduce the packet error probability. A comparison of the performance is presented for a specific code with equal Hamming distance d/sub min/, exchanging between the error correcting and error detecting capability of that code. Also, the effects of signal carrier detection on receiver error probability and throughput are investigated
	[52] 	Linnartz, J., "Effects of delay spread and noise on outage probability in cellular network," Archiv fur Elektronik und Uebertragungstechnik, vol. 48, no. 1, pp. 14-18, 1994.
Abstract: Existing techniques for (exact) analysis of the outage probability in a cellular radio network are limited to the effect of (co-channel) interference in a narrowband (one-ray) multipath fading channel. This paper models the effect of noise and a delay spread experienced by the wanted signal and all interfering signals. Results are presented for frequency-dispersive Rayleigh fading channels with an exponential power delay profile. The mathematical analysis is computationally efficient, so it may enhance the designing and planning of cellular networks in a spectrum efficient manner, allowing the use of topographical data bases
	[53] 	Linnartz, J. and Davis, J., "Outage probability in digital cellular radio networks," Conference Record of The Twenty-Sixth Asilomar Conference on Signals, Systems and Computers (Cat.No.92CH3245-8), pp. 88-92, 1992.
Abstract: The block outage probability that the voice segment is lost in digital cellular radio networks using TDMA because of a temporary fade during part of its reception is studied. The combined effects of multipath fading and shadowing of the wanted and interfering signals are considered. To this end, the model for RF outage probabilities, as appropriate for analog transmission, is extended to include the influence of the nonfade duration. The results are compared with the outage probability for blocks of zero duration, i.e., ignoring the effects of the time constants of the fading on outage probability. Results are verified by computer simulation using Ptolemy. The results suggest that previously reported outage probabilities for analog transmission are inaccurate for TDMA networks. The new model is believed relevant to the spectrum-efficient design and planning of reliable digital cellular TDMA telephone networks
	[54] 	Eleazu, C., Diesta, R., and Linnartz, J., "Base station to vehicle communication for intelligent vehicle/highway systems (IVHS)," Electronics Letters, vol. 29, no. 24, pp. 2079-2080, 1993.
Abstract: An optimum frequency reuse factor of 1 or 2 is proposed to minimise the average queueing delay and maximise throughput in a packet-switched microcellular network with BPSK transmission over dispersive Rician-fading channels. Thus, for intelligent vehicle/highway system data networks, frequency reuse can be substantially denser than has been suggested for circuit-switched cellular telephony networks
	[55] 	Linnartz, J., "Spectrum efficiency of radio data system (RDS)," IEEE Transactions on Broadcasting, vol. 39, no. 3, pp. 331-334, 1993.
Abstract: The paper addresses the use of the radio data system (RDS) for datacasting road traffic information. It is concluded that, although RDS may be essential to the early phases of introduction of novel advanced traffic information systems (ATISs), FM subcarrier transmission does not offer a spectrum-efficient solution for large-scale ATIS datacasting. The conclusions are believed relevant to the spectrum-efficient design of the future datacasting networks
	[56] 	Linnartz, J., Jong, A., and Prasad, R., "Effect of coding in digital microcellular personal communication systems with co-channel interference, fading, shadowing, and noise," IEEE Journal on Selected Areas in Communications, vol. 11, no. 6, pp. 901-910, 1993.
Abstract: An analytical model is developed for the performance of a microcellular radio network in the presence of cochannel interference and additive white Gaussian noise. The modulation schemes considered are binary phase-shift keyed (BPSK), binary frequency-shift keyed (BFSK), and quadrature phase-shift keyed (QPSK). The multiple-access channel is statistically modeled by one Rician-distributed desired signal and several uncorrelated Rayleigh plus log-normally shadowed interfering signals, propagating according to dual path loss law with a turning point. The performance is determined in terms of bit error rate (BER), outage probability, block error probability, crosstalk probability, and spectrum efficiency, considering both fast and slow multipath fading. The effect of error correction codes, consisting of blocks with equal number of bits, on the performance parameters is also studied. The computational results show that the propagation loss exponents, Rician factor, turning point, and cell size all plays a major role in the design of an efficient microcellular system
	[57] 	Linnartz, J., Jong, A., and Prasad, R., "Performance of personal communication networks with error correction coding in microcellular channels," 1st International Conference on Universal Personal Communications, ICUPC '92 Proceedings (Cat.No.92TH0434-1), pp. 11, 1992.
Abstract: The performance of microcellular radio networks is investigated by evaluating the bit error rate (BER) for a Rician fading desired signal with BPSK/BFSK/QPSK modulation in the presence of Rayleigh fading co-channel interference, log-normal shadowing and additive white Gaussian noise. The influence of the normalised reuse distance and cluster size on the BER and spectrum utilisation is investigated. Also, the probability of successful reception of a block of bits is analyzed. In particular, the effect of error correction coding on the probability of success, considering fast and slow multipath fading is addressed
	[58] 	Linnartz, J., "Exact analysis of the outage probability in multiple-user mobile radio," IEEE Transactions on Communications, vol. 40, no. 1, pp. 20-23, 1992.
Abstract: A novel mathematical method is presented to express the outage probability for a desired radio signal received from a mobile transmitter in the presence of multiple interfering signals with combined log-normal and Rayleigh fading. In contrast to previously reported analyses, this exact method avoids approximation of the PDF of the received powers of the various signals. This is useful in determining the spectrum efficiency and performance of (interference-limited) radio networks for high-capacity cellular telephony, two-way paging, packet radio and other mobile data networks
	[59] 	Linnartz, J., Hekmat, R., and Venema, R., "Near-far effects in land mobile random access networks with narrow-band Rayleigh fading channels," IEEE Transactions on Vehicular Technology, vol. 41, no. 1, pp. 77-90, 1992.
Abstract: The near-far effect of random access protocols in mobile radio channels with receiver capture is investigated. To this end, the probability of successful reception of a packet from a terminal at a known distance from the central receiver is obtained taking into account Rayleigh fading, UHF propagation attenuation, and the statistics of contending packet traffic in radio nets employing slotted ALOHA, carrier sense multiple access (CSMA) or inhibit sense multiple access (ISMA) protocols. Various models of receiver capture are compared, namely packet error rates for synchronous detection in slow- and fast-fading channels, and the probability that the signal-to-interference ratio is above a required threshold
	[60] 	Linnartz, J. and 't Jong, A., "Average bit error rate for coherent detection in macro and micro cellular radio," Sixth International Conference on Mobile Radio and Personal Communications (Conf.Publ.No.351), pp. 241-247, 1991.
Abstract: The probability of bit error is investigated, taking account of propagation effects in macrocellular and microcellular networks, noise and multiple interferers. Coherent detection of BPSK, QPSK and BFSK is considered with combined log-normal shadowing and Rayleigh fading for macrocellular radio and combined log-normal shadowing and Rician fading for microcellular radio. The effect of interference with bit intervals randomly aligned with the wanted signal is studied for the case of BPSK
	[61] 	Linnartz, J., "Slotted ALOHA land-mobile radio networks with site diversity," IEE Proceedings I (Communications, Speech and Vision), vol. 139, no. 1, pp. 58-70, 1992.
Abstract: An analytical method for investigating slotted ALOHA land-mobile networks is presented. The probability of successful reception and throughput is assessed for a single base station, taking account of contending transmissions and receiver noise. Receiver capture is assumed to occur if the received signal power exceeds the joint interference power by a certain margin, called the receiver threshold. Rayleigh fading and UHF groundwave propagation are considered. Results are extended for a cellular network considering the interference from packet transmissions in other (co-channel) cells. It is seen that in packet-switched cellular nets, frequency reuse distances may be substantially smaller than in circuit-switched (CW) telephony networks, where each cell has to be safeguarded continuously from co-channel interference. Moreover, a technique to assess the throughput of ALOHA networks with multiple, geographically-separated base stations is presented and numerical results are given for uniform Poisson-distributed packet transmissions in the service area
	[62] 	Linnartz, J., "Site diversity in land-mobile cellular telephony network with discontinuous voice transmission," European Transactions on Telecommunications and Related Technologies, vol. 2, no. 5, pp. 471-479, 1991.
Abstract: Cellular radio channels suffer from signal outages due to multipath fading and shadowing. Analytical expressions are given for the probability that the instantaneous /b C///b I/-ratio drops below a required protection ratio. A radio signal from a mobile subscriber exhibits outages at different base station sites with relatively low correlation. The quality of communication over a mobile telephone circuit can be improved by appropriately combining voice segments received at various base stations. The probability of dropping a voice segment for an end-to-end `uplink' circuit (mobile-to-PSTN) in an interference-limited cellular network with discontinuous voice transmission and macro diversity is evaluated mathematically. Asymptotic expressions of the signal outage probability for high average /b C// /b I/-ratios are presented in closed form
	[63] 	van der Plas, C. and Linnartz, J., "Stability of mobile slotted ALOHA network with Rayleigh fading, shadowing, and near-far effect," IEEE Transactions on Vehicular Technology, vol. 39, no. 4, pp. 359-366, 1990.
Abstract: Dynamic network behavior is investigated using the classical ALOHA queueing model extended to mobile channels. The focus is on the assessment of receiver capture probabilities, based on a general propagation model for mobile radio communications. Queueing of packets in a mobile slotted ALOHA network with Rayleigh fading, shadowing, and UHF groundwave propagation is studied, using a finite Markov chain model. It is shown that receiver capture, assisted by all three propagation mechanisms, reduces bistability of the network substantially compared to the retransmission strategy. Results are presented for a uniform spatial distribution of the packet traffic ordered to the ALOHA channel. The near-far effect is highlighted, since the total network performance and the spatial distribution of the attempted traffic interact
	[64] 	Safak, A., Prasad, R., and Linnartz, J., "Outage probability analysis for mobile radio systems due to correlated log-normal interferers," Communication, Control and Signal Processing.Proceedings of the 1990 Bilkent International Conference on New Trends in Communication, Control and Signal Processing, pp. 518-524, 1990.
Abstract: An approximate technique is described to find the statistics of the sum of three correlated log-normal variables. The effect of correlation on the variance and mean of the combined log-normal variables has been investigated and presented. The results obtained are applied in evaluating the outage probability of a mobile radio system assuming that the desired signal and interferers are correlated, too
	[65] 	Linnartz, J., "Near-far effects in some random-access radio systems with fading," Communication, Control and Signal Processing.Proceedings of the 1990 Bilkent International Conference on New Trends in Communication, Control and Signal Processing, pp. 504-510, 1990.
Abstract: The near-far effect and throughput of slotted ALOHA and inhibit sense multiple access in mobile radio channels with receiver capture are studied. To this end, the probability of successful reception of a packet from a known distance from the central receiver is obtained taking into account Rayleigh fading, UHF propagation attenuation, and the statistics of contending packet traffic due to a nonpersistent or 1-persistent inhibit sensing access protocol
	[66] 	Linnartz, J., Goossen, H., Hekmat, R., Pahlavan, K., and Zhang, K., "Comment on slotted ALOHA radio networks with PSK modulation in Rayleigh fading channels [and reply]," Electronics Letters, vol. 26, no. 9, pp. 593-595, 1990.
Abstract: The original article (see ibid., vol.25, no.6, 1989) proposed analytical results for receiver capture in ALOHA radio networks, considering the effects of binary PSK modulation, noise and packet size. A number of improvements are offered in this comment
	[67] 	Linnartz, J., "Modelling UHF propagation for frequency assignment in radio relay networks," AGARD Conference Proceedings No.453.Operational Decision Aids for Exploiting or Mitigating Electromagnetic Propagation Effects (AGARD-CP-453), pp. 49-1-4910, 1989.
Abstract: An account is given of experiences in developing UHF propagation models for the terrain of the North German plain which is characterised by woods and farmland. A few empirical results on the relevance of modelling the interaction between diffraction and groundwave propagation are discussed. The paper focuses mainly on statistical methods used to select appropriate models, rather than going into the physical details of propagation mechanisms. Since local variability of the field strength prohibits prediction of the feasibility of radio relay links with absolute reliability, static diversity tests are recommended to avoid antenna positioning in local multipath nulls. It is shown that such antenna position tests are worthwhile only if the propagation model forecasts local mean signal powers with sufficient reliability
	[68] 	Linnartz, J. and Prasad, R., "Threshold crossing rate and average non-fade duration in a Rayleigh-fading channel with multiple interferers," Archiv fur Elektronik und Uebertragungstechnik, vol. 43, no. 6, pp. 345-349, 1989.
Abstract: A sum of /b n/ incoherent Rayleigh-fading narrowband signals is described as a joint interference signal with Nakagami fading. Extending the theory of mobile fading for a single signal, expressions for the rate of crossing a prescribed /b C///b I/-ratio and the resulting average non-fade duration are derived. Results suggest that if the interference is due to many components, only the bandwidth of the fading of the desired signal plays an important role in these statistics. The results are useful for evaluation of packet radio networks, paging systems and other interference-limited mobile radio systems
	[69] 	Linnartz, J. and Prasad, R., "Near-far effect on slotted ALOHA channels with shadowing and capture," 39th IEEE Vehicular Technology Conference (IEEE Cat.No.89CH2739-1), pp. 809-813, 1989.
Abstract: Signal statistics are modelled in an environment of shadowing and ground wave path loss. This propagation model is used to investigate the channel performance of a slotted ALOHA network. The results are presented as receiver capture probability vs. packet propagation distance, with the log-normal variance and the offered traffic as parameters. Log-normal spatial distributions and uniform distributions of users over the coverage area are compared. The former facilitate the analysis of mobile packet-radio channels with near-far effect and shadowing and can often approximate the latter type of distribution. It is shown that stability and throughput cannot be realistically studied by (quasi-) uniform distributions. The log-normal subscriber density with a spatial spread of 8.68 dB gives a viable alternative to the study of the heavily loaded collision-type multiple-access channel
	[70] 	Linnartz, J. and Arnbak, J., "Spatial distributions of traffic in a mobile ALOHA network," EUROCON 88: 8th European Conference on Electrotechnics.Conference Proceedings on Area Communication (Cat.No.88CH2607-0), pp. 326-329, 1988.
Abstract: In a wide-area mobile ALOHA network, the central receiver in the base station(s) must handle packets with large differences in received power due to propagation effects, such as Rayleigh fading and the near-far effect. Retransmissions of colliding packets result in relatively more traffic being offered to the channel by distant terminals. An integral transform of the probability density function for the received power proves to be a useful tool for analyzing the channel behavior. A smooth weighting function for the interfering traffic is introduced to calculate the spatial distribution of throughput traffic from a given distribution of offered traffic. Iterative numerical computing is applied for the inverse problem: to obtain the distribution of traffic to be offered (including any necessary retransmissions) that yields a prescribed throughput of packet traffic from a given distance
	[71] 	Linnartz, J., Prasad, R., and Arnbak, J., "Spatial distribution of traffic in a cellular ALOHA network," Archiv fur Elektronik und Uebertragungstechnik, vol. 42, no. 1, pp. 61-63, 1988.
Abstract: The position of a mobile terminal has a significant influence on its probability to capture the central receiver in a base station of a cellular radio system using slotted ALOHA for multiple access. Integral transforms of the received power probability density function prove a useful tool for analysing spatial distributions of offered and throughput packet traffic in a mobile data network with Rayleigh fading channels. Both incoherent and coherent cumulation of interference signals are considered. In both cases, a uniform throughput distribution is synthesised numerically
	[72] 	Linnartz, J., "Spatial distribution of traffic in a cellular mobile data network," Spatial distribution of traffic in a cellular mobile data network, 1987.
Abstract: The position of a mobile terminal has a significant influence on its probability to capture the central receiver in the base station of a cellular radio system using slotted ALOHA for multiple access. Integral transforms of the probability density function for the received power prove a useful tool for analysing the relation between the spatial distributions of offered and throughput packet traffic in a mobile radio network with Rayleigh fading channels. A newly developed method to obtain the spatial distribution of throughput traffic from a prescribed spatial distribution of offered traffic is presented and illustrated with examples. Incoherent and coherent addition of interference signals is considered. The channel behaviour for heavy traffic loads is studied. In both the incoherent and coherent case, the spatial distribution of offered traffic required to ensure a prescribed spatially uniform throughput is synthesised numerically
	[73] 	Tomasin, S., Gorokhov, A., Yang, H. B., and Linnartz, J. P., "Iterative interference cancellation and channel estimation for mobile OFDM," Ieee Transactions on Wireless Communications, vol. 4, no. 1, pp. 238-245, 2005.
Keywords: (OFDM)/channel estimation/DATA-TRANSMISSION/interference cancellation/mobile communications/MODULATION/orthogonal frequency division multiplexing/RAYLEIGH FADING CHANNELS/SYSTEMS/TIME
Abstract: In mobile reception, the reliability of orthogonal frequency division multiplexing (OFDM) is limited because of the time-varying nature of the channel. This causes intercarrier interference (ICI) and increases inaccuracies in channel tracking. In this paper, we model the ICI using derivatives of the channel amplitude. This allows us to design a relatively simple receiver scheme that iteratively cancels the ICI. The design of the canceler aims at maximizing the signal-to-noise-plus-ICI ratio at the detector input. We also propose a new channel estimator, and we show that it achieves reliable mobile reception in practical situations that are relevant to terrestrial Digital Video Broadcasting (DVB-T). Extensive simulations for a receiver with one or two antennas show that a small number of iterations between ICI cancellation and channel estimation allow a reliable reception at vehicle speeds above 100 km/h
	[74] 	Gorokhov, A. and Linnartz, J. P., "Robust OFDM receivers for dispersive time-varying channels: Equalization and channel acquisition," IEEE Transactions on Communications, vol. 52, no. 4, pp. 572-583, 2004.
Keywords: DATA-TRANSMISSION/digital video broadcasting (DVB)/DISCRETE FOURIER-TRANSFORM/intercarrier interference (ICI)/mobile communications/MODULATION/multicarrier systems/orthogonal frequency division multiplexing/SYSTEMS/TIME
Abstract: In orthogonal frequency-division multiplexing, time variations of a multipath channel lead to a loss of orthogonality between the subcarriers, and thereby limit the achievable throughput. This paper proposes a general framework for a controlled removal of intercarrier interference (ICI) and channel acquisition. The core idea behind our method is to use a finite power series expansion for the time-varying frequency response, along with the known statistical properties of mobile radio channels. Channel acquisition and ICI removal are accomplished in the frequency domain and allow for any desired tradeoff between the residual ICI level, the required training for channel acquisition, and processing complexity. The proposed approach enables a high spectral efficiency (64-quadrature amplitude modulation mode) of digital video broadcasting-terrestrial in highly mobile environments
	[75] 	Jonker, W. and Linnartz, J. P., "Digital rights management in consumer electronics products," Ieee Signal Processing Magazine, vol. 21, no. 2, pp. 82-91, 2004.
Keywords: COPY PROTECTION/DVD VIDEO
Abstract: Secure electronic content distribution is essential
	[76] 	Linnartz, J. P. M. G., "Performance analysis of synchronous MC-CDMA in mobile Rayleigh channel with both delay and Doppler spreads," IEEE Transactions on Vehicular Technology, vol. 50, no. 6, pp. 1375-1387, 2001.
Keywords: Doppler effect/EQUALIZATION/FADING CHANNELS/FREQUENCY/intercarrier interference/MODULATION/multicarrier code division multiple access (MC-CDMA)/multicarrier modulation/OFDM SYSTEMS/orthogonal frequency division multiplexing/orthogonal frequency division multiplexing (OFDM)/Rayleigh fading/TIME
Abstract: Rapid time variations of the mobile communication channel have a dramatic effect on the performance of multicarrier modulation. This paper models the Doppler spread and computes its effect on the bit error rate (BER) for multicarrier code division multiple access (MC-CDMA) transmission and compares it to orthogonal frequency division multiplexing (OFDM). Also, we evaluate the transmission capacity per subcarrier to quantify the potential of MC-CDMA and (coded-) OFDM. We focus on linear receivers, in particular those using the minimum mean-square error (MMSE) criterion. Our channel and system models allow the computation of analytical performance results. Simulations verify some commonly used, yet critical assumptions
	[77] 	Maes, M., Kalker, T., Linnartz, J. P. M. G., Talstra, J., Depovere, G. F. G., and Haitsma, J., "Digital watermarking for DVD video copy protection - What issues play a role in designing an effective system?," Ieee Signal Processing Magazine, vol. 17, no. 5, pp. 47-57, 2000.
Keywords: COPY PROTECTION/DVD VIDEO
	[78] 	Bloom, J. A., Cox, I. J., Kalker, T., Linnartz, J. P. M. G., Miller, M. L., and Traw, C. B. S., "Copy protection for DVD video," Proceedings of the Ieee, vol. 87, no. 7, pp. 1267-1276, 1999.
Keywords: COPY PROTECTION/digital versatile disk (DVD)/digital video/DVD VIDEO/encryption/MPEG/tickets/watermarking
Abstract: The prospect of consumer digital versatile disk (DVD) recorders highlights the challenge of protecting copyrighted video content from piracy. We describe the copy-protection system currently under consideration for DVD. The copy-protection system broadly tries to prevent illicit copies fr anl being made from either the analog ol digital IIO channels of DVD recorders. An analog copy-protection system is utilized to protect the NTSC/PAL output channel by pr-eventing copies to VHS. The digital transmission of content is protected by a robust encryption protocol between two communicating devices. Watermarking is used to encode copy-control information retrievable from both digital and analog signals. Hence, such embedded signals avoid the need for metadata to be carried in either the digital or analog domains. Finally, the copy-protection system provides the capability for one-generation copying. We discuss some proposed solutions and some of the implementation issues that are being addressed
	[79] 	Hollmann, H. D. L., van Lint, J. H., Linnartz, J. P., and Tolhuizen, L. M. G. M., "On codes with the identifiable parent property," Journal of Combinatorial Theory Series A, vol. 82, no. 2, pp. 121-133, 1998.
Abstract: If C is a q-ary code of length n and a and b are two codewords, then c is called a descendant of a and b if c(i) is an element of {a(i), b(i)} for i = 1, ..., n. We are interested in codes C with the property that, given any descendant c, one can always identify at least one of the "parent" codewords in C. We study bounds on F(n, q), the maximal cardinality of a code C with this property, which we call the indentifiable parent property. Such codes play a role in schemes that protect against piracy of software. (C) 1998 Academic Press
	[80] 	Cox, I. J. and Linnartz, J. P. M. G., "Some general methods for tampering with watermarks," IEEE Journal on Selected Areas in Communications, vol. 16, no. 4, pp. 587-593, 1998.
Keywords: digital video
Abstract: Watermarks allow embedded signals to be extracted from audio and video content for a variety of purposes. One application is for copyright control, where it is envisaged that digital video recorders will not permit the recording of content that is watermarked as "never copy." In such a scenario, it is important that the watermark survive both normal signal transformations and attempts to remove the watermark so that an illegal copy can be made. In this paper, we discuss to what extent a watermark can be resistant to tampering and describe a variety of possible attacks
	[81] 	Hollmann, H. D. L., Linnartz, J. P. M. G., vanLint, J. H., Baggen, C. P. M. J., and Tolhuizen, L. M. G., "Protection of software algorithms executed on secure modules," Future Generation Computer Systems, vol. 13, no. 1, pp. 55-63, 1997.
Keywords: dummy instructions/secure processor/software protection/Viterbi decoder
Abstract: Loop structures in software code may reveal essential information about implemented algorithms and their parameters, even if the observer has no knowledge about which instructions are executed. Regular patterns can for instance be observed in power consumption, instruction fetches in external memory, or radiated EM energy. This paper addresses the use of dummy operations to obscure the details of the algorithm executed by the processor. We show that for a particular class of dummy insertion strategies, a Viterbi decoder can fairly reliably distinguish dummy fetches from real instruction fetches. In the second part of this paper, we study strategies to choose dummy fetches from a more general model. For certain situations, the optimum protection strategy appears to be deterministic (as opposed to random). Moreover, we show that in such a case, it is fundamentally not possible to enhance the security of the implementation by keeping the strategy for generating dummy fetches secret to the attacker
	[82] 	Tank, T. and Linnartz, J. P. M. G., "Vehicle-to-vehicle communications for AVCS platooning," IEEE Transactions on Vehicular Technology, vol. 46, no. 2, pp. 528-536, 1997.
Keywords: automated highways/FREQUENCY/land mobile radio data communication/multiple-access communication/Rician channels/SYSTEMS/TIME
Abstract: Vehicle-to-vehicle radio links suffer from multipath fading and interference from other vehicles, We discuss the impact of these effects on communication networks supporting an intelligent transportation system (ITS), in particular, automated vehicle control systems (AVCS's), A statistical model for this channel is considered, and the performance of the network involving many links is evaluated, We compare the performance of time division multiple access (TDMA), direct-sequence code division multiple access (DS-CDMA), and frequency hopping with TDMA in this environment. Reliability of the radio link is investigated by specifying the radio spectrum occupation for a given required reliability of the radio link
	[83] 	Linnartz, J. P. M. G., "Imperfect sector antenna diversity in slotted ALOHA mobile network," IEEE Transactions on Communications, vol. 44, no. 10, pp. 1322-1328, 1996.
Keywords: CHANNELS/FADING CHANNELS/PACKET RADIO NETWORK/PERFORMANCE/THROUGHPUT
Abstract: In a wireless network with path loss and fading channels, receiver capture is known to substantially enhance the performance of the slotted ALOHA random access protocol, The efficiency of narrowband slotted ALOHA radio networks can be enhanced further by using sector antennas, each receiving signals from a particular segment of the network area, This paper investigates the effect of realistic, i.e., partially overlapping antenna patterns and the resulting correlation of received power levels at different receiver branches, A method is derived for computing the joint throughput from two base station receivers with overlapping antennas patterns, The a posteriori information provided by the event of one message capturing one antenna is used to find conditional probabilities of capturing the other antennas as well. The paper shows that any overlap in the antenna patterns decreases the throughput, but transmissions from the overlapping area may face a larger probability of capture than signals from directions in which one antenna has maximum gain
	[84] 	Tomasin, S., Gorokhov, A., Yang, H. B., and Linnartz, J. P., "Iterative interference cancellation and channel estimation for mobile OFDM," Ieee Transactions on Wireless Communications, vol. 4, no. 1, pp. 238-245, 2005.
Keywords: channel estimation/digital video/FREQUENCY/intercarrier interference/interference cancellation/orthogonal frequency division multiplexing
Abstract: In mobile reception, the reliability of orthogonal frequency division multiplexing (OFDM) is limited because of the time-varying nature of the channel. This causes intercarrier interference (ICI) and increases inaccuracies in channel tracking. In this paper, we model the ICI using derivatives of the channel amplitude. This allows us to design a relatively simple receiver scheme that iteratively cancels the ICI. The design of the canceler aims at maximizing the signal-to-noise-plus-ICI ratio at the detector input. We also propose a new channel estimator, and we show that it achieves reliable mobile reception in practical situations that are relevant to terrestrial Digital Video Broadcasting (DVB-T). Extensive simulations for a receiver with one or two antennas show that a small number of iterations between ICI cancellation and channel estimation allow a reliable reception at vehicle speeds above 100 km/h
	[85] 	Gorokhov, A. and Linnartz, J. P., "Robust OFDM receivers for dispersive time-varying channels: Equalization and channel acquisition," IEEE Transactions on Communications, vol. 52, no. 4, pp. 572-583, 2004.
Keywords: CHANNELS/digital video/EQUALIZATION/FREQUENCY/intercarrier interference/MODULATION/orthogonal frequency division multiplexing/THROUGHPUT/TIME
Abstract: In orthogonal frequency-division multiplexing, time variations of a multipath channel lead to a loss of orthogonality between the subcarriers, and thereby limit the achievable throughput. This paper proposes a general framework for a controlled removal of intercarrier interference (ICI) and channel acquisition. The core idea behind our method is to use a finite power series expansion for the time-varying frequency response, along with the known statistical properties of mobile radio channels. Channel acquisition and ICI removal are accomplished in the frequency domain and allow for any desired tradeoff between the residual ICI level, the required training for channel acquisition, and processing complexity. The proposed approach enables a high spectral efficiency (64-quadrature amplitude modulation mode) of digital video broadcasting-terrestrial in highly mobile environments
	[86] 	Jonker, W. and Linnartz, J. P., "Digital rights management in consumer electronics products," Ieee Signal Processing Magazine, vol. 21, no. 2, pp. 82-91, 2004.
Abstract: Secure electronic content distribution is essential
	[87] 	van Rijnsoever, B. J., Lenoir, P., and Linnartz, J. P. M. G., "Interoperable protection for digital multimedia content,"  Journal of Vlsi Signal Processing Systems for Signal Image and Video Technology, vol. 34, no. 1-2, pp. 167-179, 2003.
Keywords: SYSTEMS
Abstract: Interoperability between systems for secure delivery of content (audio and video) over the Internet or via digital television broadcasting is still hampered by the lack of interoperability among proprietary content protection systems. The OPIMA (Open Platform Initiative for Multimedia Access) specification offers a generic solution for multimedia terminals, in which the end-user's terminal is adapted to a content protection system by downloading a corresponding plug-in. This paper describes the OPIMA solution and shows how it can be applied
	[88] 	Linnartz, J. P. M. G., "Performance analysis of synchronous MC-CDMA in mobile Rayleigh channel with both delay and Doppler spreads," IEEE Transactions on Vehicular Technology, vol. 50, no. 6, pp. 1375-1387, 2001.
Keywords: FREQUENCY/MODULATION/multicarrier modulation/orthogonal frequency division multiplexing/PERFORMANCE/TIME
Abstract: Rapid time variations of the mobile communication channel have a dramatic effect on the performance of multicarrier modulation. This paper models the Doppler spread and computes its effect on the bit error rate (BER) for multicarrier code division multiple access (MC-CDMA) transmission and compares it to orthogonal frequency division multiplexing (OFDM). Also, we evaluate the transmission capacity per subcarrier to quantify the potential of MC-CDMA and (coded-) OFDM. We focus on linear receivers, in particular those using the minimum mean-square error (MMSE) criterion. Our channel and system models allow the computation of analytical performance results. Simulations verify some commonly used, yet critical assumptions
	[89] 	Linnartz, J. P., Depovere, G., and Kalker, T., "On the design of a watermarking system: Considerations and rationales," Information Hiding, Proceedings, vol. 1768 pp. 253-269, 2000.
Keywords: COPY PROTECTION/PERFORMANCE/SYSTEMS/watermarking
Abstract: This paper summarizes considerations and rationales for the design of a watermark detector. In particular, we relate watermark detection to the problem of signal detection in the presence of (structured) noise. The paper builds on the mathematical results from several previously published papers (by our own research group or by others) to verify and support our discussion. In an attempt to unify the theoretical analysis of watermarking schemes, we propose several extensions which clarify the interrelations between the various schemes. New results include the matched filter with whitening, where we consider the effect of the image and watermark spectra and imperfect setting of filter coefficients. The paper reflects our practical experience in developing watermarking systems for DVD copy protection and broadcast monitoring. The aim of this paper is to further develop the insight in the performance of watermark detectors, to discuss appropriate models for their analysis and to provide an intuitive rationale for making design choices for a watermark detector
	[90] 	Maes, M., Kalker, T., Linnartz, J. P. M. G., Talstra, J., Depovere, G. F. G., and Haitsma, J., "Digital watermarking for DVD video copy protection - What issues play a role in designing an effective system?," Ieee Signal Processing Magazine, vol. 17, no. 5, pp. 47-57, 2000.
Keywords: COPY PROTECTION/DVD VIDEO/watermarking
	[91] 	Linnartz, J. P. M. G. and Van Dijk, M., Analysis of the sensitivity attack against electronic watermarks in images 1998, pp. 258-272.
Abstract: some applications of electronic watermarks, the device that detects whether content contains a watermark or not is in public domain. Attackers can misuse such detector as an oracle that reveals up to one bit of information about the watermark in each experiment. An information-theoretical analysis of the information leakage is provided, and a method is proposed to reduce the information leakage by orders of magnitude
	[92] 	Linnartz, J. P., Kalker, T., and Depovere, G., "Modelling the false alarm and missed detection rate for electronic watermarks," Information Hiding, vol. 1525 pp. 329-343, 1998.
Keywords: SYSTEMS
Abstract: Theoretical modeling of watermarks allow prediction of the detector reliability and facilitates the development of more reliable systems. In particular, mathematical evaluation is relevant to estimate the rate at which "false alarms" occur. In this paper, the probability of incorrect detection (missed detection or false alarm) is expressed in terms of the watermark-energy-to-image-luminance-variance ratio. We present some counterintuitive results which show for instance that the reliability of detection significantly depends on spatial correlation in watermark. Moreover we find that a small but uncompensated random DC component in the watermark can have a significant effect on the reliability
	[93] 	Linnartz, J. P. M. G. and Talstra, J. C., MPEG PTY-Marks: Cheap detection of embedded copyright data in DVD-video 1998, pp. 221-240.
Keywords: digital video/DVD VIDEO/MPEG
Abstract: In this paper we propose a method to watermark digital video content in such a way that detection in consumer electronics equipment is possible with very little hardware (a few thousand gates). The method proposes to modify the MPEG encoding procedure to choose the so-called Picture Type of video-frames not from a regular sequence but according to a message one would like to transmit. Removal of this embedded message, the PTY-Mark, from the resulting MPEG-stream without jeopardizing video quality is only possible after a complete MPEG decoding and re-encoding cycle. We investigate the modifications to current MPEG encoders which are necessary to accommodate these PTY-Marks. Based on tests we comment on their feasibility. Detection of watermarks without secrets is very reminiscent of "public-key" cryptography. We discuss this relationship by contrasting PTY-marks with pixel-watermarking
	[94] 	Linnartz, J. P. M. G., "The "ticket" concept for copy control based on embedded signalling," Computer Security - Esorics 98, vol. 1485 pp. 257-274, 1998.
Abstract: This application-oriented paper discusses the use of electronic watermarks (also called embedded signaling) for copy control. Playback Control and Copy-Once are described. The 'ticket concept' is presented to provide these functionalities. Although the ticket shows similarities with a digital signature, there are essential differences. For instance, the ticket allows typical modifications of the content, which are common practice in transmission, storage and presentation of video. The concept is part of a proposal currently under investigation for standardization of DVD/CPTWG copy control. This paper also compares the ticket concept with other solutions, such as embedding a secondary mark at the recorder and using a signature scheme
	[95] 	Bloom, J. A., Cox, I. J., Kalker, T., Linnartz, J. P. M. G., Miller, M. L., and Traw, C. B. S., "Copy protection for DVD video," Proceedings of the Ieee, vol. 87, no. 7, pp. 1267-1276, 1999.
Keywords: CHANNELS/COPY PROTECTION/DVD VIDEO/encryption/watermarking
Abstract: The prospect of consumer digital versatile disk (DVD) recorders highlights the challenge of protecting copyrighted video content from piracy. We describe the copy-protection system currently under consideration for DVD. The copy-protection system broadly tries to prevent illicit copies fr anl being made from either the analog ol digital IIO channels of DVD recorders. An analog copy-protection system is utilized to protect the NTSC/PAL output channel by pr-eventing copies to VHS. The digital transmission of content is protected by a robust encryption protocol between two communicating devices. Watermarking is used to encode copy-control information retrievable from both digital and analog signals. Hence, such embedded signals avoid the need for metadata to be carried in either the digital or analog domains. Finally, the copy-protection system provides the capability for one-generation copying. We discuss some proposed solutions and some of the implementation issues that are being addressed
	[96] 	Cox, I. J. and Linnartz, J. P. M. G., "Some general methods for tampering with watermarks," IEEE Journal on Selected Areas in Communications, vol. 16, no. 4, pp. 587-593, 1998.
Keywords: digital video
Abstract: Watermarks allow embedded signals to be extracted from audio and video content for a variety of purposes. One application is for copyright control, where it is envisaged that digital video recorders will not permit the recording of content that is watermarked as "never copy." In such a scenario, it is important that the watermark survive both normal signal transformations and attempts to remove the watermark so that an illegal copy can be made. In this paper, we discuss to what extent a watermark can be resistant to tampering and describe a variety of possible attacks
	[97] 	Tank, T. and Linnartz, J. P. M. G., "Vehicle-to-vehicle communications for AVCS platooning," IEEE Transactions on Vehicular Technology, vol. 46, no. 2, pp. 528-536, 1997.
Keywords: FREQUENCY/PERFORMANCE/SYSTEMS/TIME
Abstract: Vehicle-to-vehicle radio links suffer from multipath fading and interference from other vehicles, We discuss the impact of these effects on communication networks supporting an intelligent transportation system (ITS), in particular, automated vehicle control systems (AVCS's), A statistical model for this channel is considered, and the performance of the network involving many links is evaluated, We compare the performance of time division multiple access (TDMA), direct-sequence code division multiple access (DS-CDMA), and frequency hopping with TDMA in this environment. Reliability of the radio link is investigated by specifying the radio spectrum occupation for a given required reliability of the radio link
	[98] 	Linnartz, J. P. M. G., "Imperfect sector antenna diversity in slotted ALOHA mobile network," IEEE Transactions on Communications, vol. 44, no. 10, pp. 1322-1328, 1996.
Keywords: CHANNELS/FADING CHANNELS/PERFORMANCE/THROUGHPUT
Abstract: In a wireless network with path loss and fading channels, receiver capture is known to substantially enhance the performance of the slotted ALOHA random access protocol, The efficiency of narrowband slotted ALOHA radio networks can be enhanced further by using sector antennas, each receiving signals from a particular segment of the network area, This paper investigates the effect of realistic, i.e., partially overlapping antenna patterns and the resulting correlation of received power levels at different receiver branches, A method is derived for computing the joint throughput from two base station receivers with overlapping antennas patterns, The a posteriori information provided by the event of one message capturing one antenna is used to find conditional probabilities of capturing the other antennas as well. The paper shows that any overlap in the antenna patterns decreases the throughput, but transmissions from the overlapping area may face a larger probability of capture than signals from directions in which one antenna has maximum gain
	[99] 	Linnartz, J. P. M. G., Awater, G. A., and Venema, R. J., "Throughput of Inhibit Sense Multiple-Access with Propagation Delays," IEEE Transactions on Communications, vol. 42, no. 1, pp. 119-126, 1994.
Keywords: THROUGHPUT
Abstract: A large number of terminals transmitting data packets over a common radio channel to a central base station is studied. In inhibit sense multiple access (ISMA), the base station broadcasts a busy signal when an incoming packet is being received, to inhibit other terminals from colliding transmissions. This busy signal arrives at each terminal with a propagation delay, proportional to the distance between the base station and the terminal. This leads to unfairness in the probability of successfully transmitting a data packet, since nearby terminals have more up-to-date information on the actual channel status than remote terminals. This unfairness is additional to the advantage that nearby terminals have because of the capture effect, which is also considered here. The paper applies nonstationary Poisson processes to describe the random arrivals of data packets at the central receiver. It is shown that the probability of a successful attempt to transmit a packet decreases, approximately linearly with the distance between the transmitter and the central receiver. The total throughput is also assessed, and is found that the assumption of a fixed propagation delay adopted in CSMA studies by others gives too optimistic results for ISMA. Moreover, our analysis suggests a subtle change of the fixed delay approximation that enhances its accuracy, without adding complexity. The effect of propagation delays in random access radio networks are of increasing importance, since newly developed sq-stems are designed to transmit with increasingly high bit rates
	[100] 	Yee, N., Linnartz, J. P. M. G., and Fettweis, G., "Multicarrier Cdma in Indoor Wireless Radio Networks," IEICE Transactions on Communications, vol. E77B, no. 7, pp. 900-904, 1994.
Keywords: MODULATION/PERFORMANCE
Abstract: This paper examines a novel digital modulation/multiple access technique called Multi-Carrier Code Division Multiple Access (MC-CDMA) where each data symbol is transmitted at multiple narrowband subcarriers. Each subcarrier is encoded with a phase offset of 0 or pi based on a spreading code. Analytical results are presented on the performance of this modulation scheme in an indoor wireless multipath radio channel
	[101] 	Linnartz, J. P. M. G. and Westerman, M., "Performance Analysis of Road Traffic Data-Collection System," IEICE Transactions on Communications, vol. E77B, no. 7, pp. 934-938, 1994.
Keywords: PERFORMANCE/SYSTEMS/TIME
Abstract: Advanced Traveller Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) require real-time traffic data to observe and control the trafic flow. Still, there is a lack of proficient traffic monitoring systems. One method to collect such data is using particular equipped vehicles, called 'probes', transmitting experienced travel times to base stations which in turn are connected to a traffic control center. In this paper we analyse the performance of a radio network for collecting real-time traffic data from probes. The results reveal that random transmission of traffic reports is a (spectrum) efficient, inexpensive and flexible method for collecting road traffic data that can provide reliable traffic monitoring
	[102] 	Linnartz, J. P. M. G., "Spectrum Efficiency of Radio Data System (Rds)," IEEE Transactions on Broadcasting, vol. 39, no. 3, pp. 331-334, 1993.
Keywords: SYSTEMS
Abstract: This paper addresses the use of the Radio Data System (RDS) for datacasting road traffic information. We conclude that, although RDS may be is essential to the early phases of introduction of novel Advanced Traffic Information Systems (ATIS), FM subcarrier transmission does not offer a spectrum efficient solution for large-scale ATIS datacasting. The conclusions are believed relevant to the spectrum-efficient design of the future datacasting networks
	[103] 	Linnartz, J. P. M. G., Jong, A. J. T., and Prasad, R., "Effect of Coding in Digital Microcellular Personal Communication-Systems with Cochannnel Interference, Fading, Shadowing, and Noise," IEEE Journal on Selected Areas in Communications, vol. 11, no. 6, pp. 901-910, 1993.
Keywords: MODULATION/PERFORMANCE
Abstract: An analytical model is developed for the performance of a microcellular radio network in the presence of co-channel interference and additive white Gaussian noise. The modulation schemes considered are BPSK, BFSK, and QPSK. The multiple-access channel is statistically modeled by one Rician-distributed desired signal and several uncorrelated Rayleigh plus log-normally shadowed interfering signals, propagating according to dual path loss law with a turning point. The performance is determined in terms of bit error rate (BER), outage probability, block error probability, crosstalk probability, and spectrum efficiency, considering both fast and slow multipath fading. The effect of error correction codes, consisting of blocks with equal number of bits, on the performance parameters is also studied. The computational results show that the propagation loss exponents, Rician factor, turning point, and cell size all play a major role in the design of an efficient microcellular system. A proper compromise has to be achieved between spectrum efficiency and bit error rate. The error correction capability of BCH code has a significant effect on the performance for fast multipath fading. However, with slow multipath fading and/or severe shadowing, the effect of error correction is much smaller. Unshadowed fast multipath fading is less harmful than (shadowed or unshadowed) slow multipath fading when appropriate coding is used
	[104] 	Linnartz, J. P. M. G., "Exact Analysis of the Outage Probability in Multiple-User Mobile Radio," IEEE Transactions on Communications, vol. 40, no. 1, pp. 20-23, 1992.
Keywords: PERFORMANCE/Rayleigh fading
Abstract: A novel mathematical method is presented to express the outage probability for a desired radio signal received from a mobile transmitter in the presence of multiple interfering signals with combined log-normal and Rayleigh fading. In contrast to previously reported analysis, this exact method avoids approximation of the pdf of the received powers of the various signals. This is useful in determining the spectrum efficiency and performance of (interference-limited) radio networks for high-capacity cellular telephony, two-way paging, packet radio and other mobile data networks
	[105] 	Linnartz, J. P. M. G., Hekmat, R., and Venema, R. J., "Near Far Effects in Land Mobile Random-Access Networks with Narrow-Band Rayleigh Fading Channels," IEEE Transactions on Vehicular Technology, vol. 41, no. 1, pp. 77-90, 1992.
Keywords: CHANNELS/FADING CHANNELS/Rayleigh fading/RAYLEIGH FADING CHANNELS
Abstract: The near-far effect of random access protocols in mobile radio channels with receiver capture is investigated. To this end, the probability of successful reception of a packet from a terminal at a known distance from the central receiver is obtained taking into account Rayleigh fading, UHF propagation attenuation, and the statistics of contending packet traffic in radio nets employing slotted ALOHA, carrier sense multiple access (CSMA) or inhibit sense multiple access (ISMA) protocols. Various models of receiver capture are compared, namely packet error rates for synchronous detection in slow- and fast-fading channels, and the probability that the signal-to-interference ratio is above a required threshold
	[106] 	Linnartz, J. P. M. G., "Slotted Aloha Land-Mobile Radio Networks with Site Diversity," Iee Proceedings-I Communications Speech and Vision, vol. 139, no. 1, pp. 58-70, 1992.
Keywords: FREQUENCY/Rayleigh fading/THROUGHPUT
Abstract: An analytical method for investigating slotted ALOHA land-mobile networks is presented. The probability of successful reception and throughput is assessed for a single base station, taking account of contending transmissions and receiver noise. Receiver capture is assumed to occur if the received signal power exceeds the joint interference power by a certain margin, called the receiver threshold. Rayleigh fading and UHF groundwave propagation are considered. Results are extended for a cellular network considering the interference from packet transmissions in other (co-channel) cells. It is seen that in packet-switched cellular nets, frequency re-use distances may be substantially smaller than in circuit-switched (CW) telephony networks, where each cell has to be safeguarded continuously from co-channel interference. Moreover, a technique to assess the throughput of ALOHA networks with multiple, geographically-separated base stations is presented and numerical results are given for uniform Poisson-distributed packet transmissions in the service area
	[107] 	Vanderplas, C. and Linnartz, J. P. M. G., "Stability of Mobile Slotted Aloha Network with Rayleigh Fading, Shadowing, and Near Far Effect," IEEE Transactions on Vehicular Technology, vol. 39, no. 4, pp. 359-366, 1990.
Keywords: Rayleigh fading