Resource auction multiple access (RAMA) in the cellular environment

Resource auction multiple access (RAMA) is a technique for rapidly assigning communication resources (e.g., TDMA time slots) in a wireless environment. This scheme is deterministic in that, barring errors caused by fading and noise, a resource assignment is made in each and every assignment cycle. Previous papers reported on the call assignment capacity of this technique and also demonstrated its capabilities for statistical speech multiplexing. In these studies, we used a selected set of GSM parameters while assuming perfect radio channel operation. In this paper, we extend the previous work in two directions: (1) we examine the effects of channel fading and noise; and (2) we consider both GSM and IS-54 cellular environments. Propagation is modeled, for purposes of this study, as flat Rayleigh fading, with mean propagation loss as a parameter. We focus on the subscriber-to-base link, which is most vulnerable to RAMA errors, and consider several forms of diversity at the base. We also consider two RAMA modes (call assignment only and statistical speech multiplexing). RAMA signaling is two-level amplitude shift keying (ASK). We show that a simple form of two-branch diversity can be very effective. Our final results show the probability of assignment error as a function of mean propagation loss for different diversities, systems, and average transmit powers. In IS-54, for example, simple diversity and an average transmit power of 100 mW yields error probabilities of 58 or less for losses as high as 154 dB. We also show that such error rates are more than adequate for purposes of call assignment.<
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