What Does Packet Reservation Multiple Access Mean?
Packet Reservation Multiple Access (PRMA) refers to a multiple access strategy with frames of a fixed number of slots. In case a terminal contains a set of data packets or speech segments to deliver, it competes to gain access in any free slot.
If it can successfully capture the base station (BS), the terminal acquires reservation in the associated slots of the next frames, right until it releases the reservation. In PRMA, adjacent cells make use of distinct carrier frequencies in line with a cellular reuse plan. The fundamental process of PRMA includes occupying a time slot only at the time of speech talkspurts and releasing the channel at the time of silence periods.
Techopedia Explains Packet Reservation Multiple Access
Although PRMA was previously widely used for speech traffic, it can be used for data users as well because of its bandwidth efficiency, random access, and reservation qualities. The flexibility in receiving various traffic bit rates makes PRMA a fine candidate for multi-rate data traffic.
A benefit of PRMA is that it demands minimal central control. As hand-overs call for minimum intervention from the base station, an active voice terminal which moves into another cell drops its slot reservations. Therefore, it has to re-contend with other terminals to broadcast the left-over voice packets. In addition, the terminal demands registration with the new base station. The resulting delay can compel the terminal to lose voice packets, thus degrading its overall performance.
One key benefit of the PRMA protocol is that it can be used in combination with existing CDMA or TDMA-based systems. It can also be incorporated with the next-gen WCDMA systems. PRMA-centered protocol is ideal for multimedia traffic due to its dynamic and flexible bandwidth-allocation process.
- TDMA with slotted ALOHA reservation system
- Source rates are 32 kbit/sec
- Frame Duration is 16 msec ( 62.5 frames/sec)
- 20 slots per frame
- Channel bit rate is 720 kbit/sec and bandwidth is 720 khz
- 576 bits per slot (contains 64 bit overhead)
- Packet dropping rate is 1%
- Supports data and voice