JPL's Wireless Communication Reference Website Chapter: Network Concepts and Standards Chapter: Cellular Networks Section: Multiple Access, Random Access

Packet Reservation Multiple Access

Packet Reservation Multiple Access (PRMA) has been developed by D. Goodman et al. at Winlab at Rutgers University. It applies Time Assigned Speech Interpolation (TASI) as multiple access method in wireless networks, while previously TASI was almost exclusively used for multiplexing on satellite links.

PRMA is a multiple access scheme with frames of a fixed number of slots. If a terminal has a series of data packets (or speech segments) to transmit, it competes for access in any free slot. If it successfully captures the base station, the terminal gains reservation in the corresponding slots of the next frames, until it releases the reservation.

In PRMA, adjacent cells use different carrier frequencies according to a cellular reuse plan.

PRMA facts

• TDMA with slotted ALOHA reservation scheme
• Frame Duration 16 msec (62.5 frames/sec)
• Source rates 32 kbit/sec.
• Channel bit rate 720 kbit/sec; Bandwidth 720 khz.
• 20 slots per frame
• Wireless version of satelite telephony technology:
  DSI (Digital Speech Interpolation) or TASI (Time Assigned Speech Interpolation)
• One carrier supports 26 - 39 simultaneous calls with a packet dropping rate » 1%
• 576 bits/slot (includes 64 bit overhead)
• Voice and Data

JPL's Wireless Communication Reference Website © Jean-Paul M.G. Linnartz, 1993, 1995.