High data-rate packet communications for cellular networks usingCDMA: algorithms and performance

摘要

The advantages of code division multiple access (CDMA) forncellular voice have become well known, and IS-95-based systems have nownbeen widely deployed. Attention is now focused on higher data-ratenpacket services for cellular systems. Although many packet multiplenaccess schemes have been studied over the years, researchers have oftennstudied single cell performance and ignored reuse. Moreover, directnsequence spread spectrum (DSSS) has been considered unsuitable for highndata-rate packet multiple access since spreading limits the permittedndata rates, DSSS requires large overhead (preambles) for acquisition andnrequires closed-loop power control. In this paper, we describe a schemenfor high data-rate packet service using CDMA that addresses all of thenabove problems and has been standardized in Revision B of IS-95. A lownrate fundamental code channel is maintained that eliminates the need fornlong preamble and provides closed-loop power control. Reuse is managednby the infrastructure through a “burst-level” admissionncontrol based on load and interference-level measurements at the basenstations and mobiles. We report on the feasibility of such a burst-modenpacket data service for cellular CDMA networks. The focus is not only onnthe performance of high data-rate users, but also on the impact on voicenusers sharing the CDMA band. We propose a multitiered performancenanalysis methodology consisting of a mix of static simulations, dynamicnsimulations at different time scales, and analytic methods to addressnthe various feasibility issues: impact on coverage; capacity; powerncontrol; and effectiveness of burst admission algorithms. Based on thencurrent study, we can conclude that the proposed approach is well suitednfor third-generation wideband CDMA systems being considered fornstandardization throughout the world