JPL's Wireless Communication Reference Website Chapter: Authors and Contributors

Bernhard H.Walke

Member of the Wireless Communication Advisory Board.

ComNets research group

Methods

• Performance analysis of communication systems by
  • modeling,
  • mathematical analysis,
  • stochastic simulation,

Applications

• Design and optimization of services and protocols for digital communication networks, including
  • formal specification (System Description Language),
  • implementation by rapid prototyping for field trials,
• Network architectures (IN, UPT, ..)
• CASE tools for software engineering based on formal specification methods including traffic performance optimization
• Models of scenario specific radio propagation (in-/outdoors) and of mobility.

Examples of current work:

1.

Topology design and performance optimized layout for
radio based and fixed networks under constraints (location of
nodes, meshing, etc.), DFG-project.

• linear optimization under cost, traffic, performance aspects
• genetic and simulated annealing algorithms
• analysis based on stochastic simulation
• design tool for any choice of mobile and fixed network.

2.

Broadband-ISDN:

• mathem. analysis of correlated (batch) input processes to an ATM multiplexer. Calculation of loss probability, delay, etc
• modelling of ATM sources,
• rare events simulation techniques (cell loss probability),
• ATM testbed experiments (country of North-Rhine Westf.).

3.

Intelligent Network based services for Universal Personal
Telecommunications (Race2/Mobilise, BMBF ATMmobil):

• free choice of network access point for roaming user,
• concept of a subscribers role (role dependent profile),
• performance analysis of signaling system No. 7 in IN and of optimum data distribution for various mixes of IN-services.

SDL-specification and CASE-based implementation of

• window based control of a Personal Digital Assistant,
• application oriented services in the IN,
• security architecture for authentification of network elements,
• framework service, supporting full subscriber mobility including control of profile and service-translation under user control.

4.

Development and performance evaluation of protocols for
the GSM cellular digital mobile radio system:

• data communication (contributions to ETSI-SMG 4):
  • RLP: with adaptive (convolutional, punctured and adaptive coding, type 2 ARQ-protocols,
  • improvements to (non/transparent) telefax protocols ,
  • GPRS packet radio protocols (Q.922 frame relay, X.25) trunked mobile radio services (TETRA) in GSM,
• modelling of radio coverage for realistic scenarios,
• pattern recognition techniques for localization of mobiles and handover support,
• hierarchical cell structures and dynamic channel assignment

5.

Simulation of empirical and mathem. models of the radio
propagation at 0.9, 1.8, 5, 40 and 60 GHz in/outdoors by,
true raytracing and mirror methods.

6.

Wireless ATM system design for cellular, LAN, local loop
and residential applications (Race2/MBS [mobile broadband system],
ACTS/Samba, BMBF ATMmobil [project leader of system design group):

• air interface and interworking functions definition and development,
• WATM system simulator,
• software prototyping for the various demonstrators,
• intelligent control algorithms for beamforming antennas,
• ATM-network handover support: ATM mobility server.

7.

Modelling and performance evaluation of radio LANs
(HiperLAN, WLAN 802.11)

• multi-hop mobile radio networks analysis,
• raytracing based radio coverage prediction,
• mobility modeling,
• design of ATM-based radio LAN including relays,
• radio access network via line-of-sight radio, with ATM-cell transmission and switching techniques.

8.

Digital short-range radio for road transport applications

• Electronic debiting protocols performance (Drive2/COMIS, Telematics/VASCO projects),
• integrated protocol architecture: Drive2/Gerdien,
• CDMA-techniques and access protocols,
• CEN/CENELEC projects.

9.

ETSI/DECT

• Simulator Desi (radio coverage, mobility, protocols, traffic)
• Development of decentral handover algorithms,
• Analysis and planning of DECT-systems in a given scenario (building details etc.) based on simulated and measured propagation data,
• DECT for the last mile solutions and coverage prediction,
• DECT capacity predictions for local loop,
• DECT large field trials participation,
• Integration of DECT as a subsystem to GSM,
• DECT/GSM/TETRA for distributed sensor/actuator applications.

10.

ETSI/TETRA

• Systems simulator Tetris,
• SDL-specification of packet data optimized and voice&data protocols,
• investigations in direct mode protocols.

11.

Software development techniques based on formal
specification methods (BMBF/SPEET project)

• automatic generation of protocol modules for stochastic performance simulation from SDL specifications,
• definition of the processing power needed for a given load,
• CASE tool based prototyping of protocols,
• design of new processor architectures for protocol support.

12.

Land mobile satellite radio (Race2/SAINT, ACTS/Insured):
Integration of cellular and mobile satellite systems.

• Simulation of satellite coverage, based on realistic antennas,
• access protocols for portable mobiles,
• radio propagation, access protocols, dynamic channel allocation, interworking of terrestrial and satellite system,
• routing and switching via satellites.

13.

Probabilistic state machine models of radio channels based
on level crossing rates combined with deterministic extended
finite state machine models for receivers and communication
protocols

• development of the models
• minimization of the state space
• exact calculation of the performance parameters (throughput, delay, repeated transmissions, etc.)

14.

Spectrum compatibility definition for mobile radio systems
to optimize guard band spaces by stochastic simulation studies:

• consideration of radio interference only,
• consideration of the full systems protocols.

15.

Multimedia based university lectures (Internet WWW)
Visualization of GSM functions (Telematics/Electra project)

16.

Development of tools & techniques for performance analysis:

• object oriented simulations class library CNCL
• specific simulator tools SIC+, SIMCO3++, GOOSE, GSM, DESI, RAY,
• formula manipulation tool (SCAFE).

Structure of the ComNets research group:

• 29 scientific assistants (fully employed),
• 3 scientific assistants (half day paid),
• 20 to 30 students assistants (part time jobs).

JPL's Wireless Communication Reference Website