IS-95 enhancements for multimedia services

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Abstract
Existing code division multiple access (CDMA) systems, such as the IS-95 digital cellular system, support data and voice traffic at a basic rate as well as lower fractional rates. A backward-compatible system, known as multicode CDMA (MC-CDMA), has been proposed as a mechanism to allow higher-rate services under the IS-95 infrastructure. MC-CDMA enables dynamic packet-like user access with low overhead and high efficiency. This paper describes MC-CDMA and focuses on several issues related to its implementation, exploring both high-level system design and details of hardware implementation. The load- and interference-based demand assignment (LIDA) access control mechanism allows dynamic data rate access by balancing and controlling mixed traffic interference in a CDMA system. LIDA builds on existing pilot measurement and soft handoff protocols and thus can be integrated easily with IS-95. Also discussed are forward link interference suppression schemes that mitigate multipath impairments, resulting in increased capacity and/or improving quality. The paper concludes by describing an efficient design for a bidirectional 56-kb/s MC-CDMA mobile transceiver that requires only minimally increased complexity when compared with a conventional CDMA tranceiver. Together with all these enhancements, MC-CDMA provides a simple and effective transition mechanism for future wireless multimedia services.