Multidimensional PRMA (MD PRMA)-a versatile medium access strategy for the UMTS mobile to base station channel

Multidimensional packet reservation multiple access (MD PRMA) is proposed as a medium access strategy for the UMTS uplink channel. It embraces both code division PRMA (CDPRMA) and frequency division PRMA (FDPRMA) and is suitable for several air interface candidates for third generation mobile communications systems. In MD PRMA slots are defined not only in the time domain, but also in the frequency or “code domain”, to increase the total number of slots per frame and thereby the multiplexing efficiency η_max. This is particularly important when only a limited number of slots per frame are available, for instance 8 as in GSM, where η_max for voice-only traffic is only 0.67 with conventional PRMA on a single carrier, but 0.85 with 4 carriers and 0.90 with 8 carriers pooled together for FDPRMA operation. An adapted pseudo Bayesian algorithm is introduced to stabilise the protocol and simulation results are presented for FDPRMA with various sets of design parameters