Capture division packet access: a new cellular access architecture for future PCNs

Abstract

The authors describe a new cellular access architecture, known as capture-division packet access, which is a packet-oriented architecture able to support the constant bit rate traffic and variable bandwidth on demand necessary for multimedia traffic. The approach integrates the multiple access and channel reuse issues to achieve a high degree of spectral efficiency, and presents general advantages even if used for delay-constrained circuit-oriented traffic. Unlike CDMA and TDMA, wherein the effective data rate of each connection is typically a small fraction of the total radio channel allocated for PCN, the CDPA approach allows each user to access the entire channel, if necessary, for brief periods of time (packet access). Spectrum sharing is accomplished by exploiting the different path losses suffered by the various signals as they appear at the base stations (the capture effect), with co-channel interference abated through time diversity (colliding users do not successively retry in the same time interval). Results suggest that abating co-channel interference by random retransmission may be more effective than spatial isolation at cells using the same channel, as is usual in FDMA-TDMA systems.