Future microcellular systems will require distributed network control. A packet-switched network is particularly suitable for this requirement. Moreover, packet switching naturally accommodates speech activity detection to improve Vation-ALOHA protocol for packet speech transmission from wireless terminals to a base station. Because PRMA is a statistical multiplexer, the channel becomes congested when to0 many terminals are active. Voice packets require prompt delivery, and therefore PRMA responds to congestion by dropping packets ooint analvsis is used to evaluate system behavior. We derive the A * System Goodman et al. proposed packet reservation multiple access (PRMA) for packet voice terminals in cellular systems nals Since conversational speech produces multipacket messages during talkspurts. The present paper presents an analysis of PRMA, a modification of R-ALOHA for indoor microcellular applications. This particular application implies that cation implies that delayed Packets are dropped. These modi-capacity. Packet reservation multiple access (PRMA) is a Reser-14i. A reservation protocol is appropriate for speech termidelayed beyond a specified time limit. In this paper, equilibrium the are The speech appliprobability of packet dropping given the number of simultaneous conversations. We also establish conditions for system stability and efficiency. Numerical calculations based on the theory show close agreement with computer simulations. They also provide valuable guides to system design. For a particular example we find that speech activity detection permits 37 speech terminals to share a PRMA channel with 20 slots per frame, with a packet dropping probability of less than 1%.

We have recently examined, for possible application to digital mobile radio telephony, a digital spread‐spectrum technique employing multiple frequency‐shift keying (MFSK) modulation with code‐division‐multiple access (CDMA) by frequency‐hopping over a common bandwidth. The system uses the cellular approach where all mobiles within a cell communicate with a fixed base station in the cell. An analysis of base‐to‐mobile transmission shows that mutual interference limits the number of users which the system can accommodate at a given error rate. This paper describes a new decoding scheme to reduce mutual interference which makes use of the well‐defined algebraic structure of the users' addresses. Analysis of the new decoder at high signal to noise (s/n) ratio shows it to outperform conventional decoding, allowing a 50 to 60 percent increase in the number of users who can simultaneously share the system at a given error rate. We describe a simple implementation of the decoder using shift registers.

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A recent paper described an improved decoding scheme for a frequency-hopped multilevel FSK system. We examined this multiple access communication system for possible application in satellite communication and mobile radio telephony. The new decoder, using the known algebraic structure of the users' addresses, reduces mutual interference and achieves a 50 to 60 percent increase in efficiency over conventional decoding. The present paper shows how additional decoding can further increase the efficiency, bringing it very close (within half a percent) to optimum. The scheme makes use of infor mation derived while decoding the messages of other users and thus is especially attractive for the base station, where such information is readily available and does not require a significant increase in complexity. Compared to conventional decoding, the new scheme more than doubles the number of simultaneous users.

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