Evolution of the reverse link of CDMA-based systems to support high-speed data

Abstract

Development of an upcoming release of the CDMA2000* family of standards is expected to focus on enhancing the reverse link (RL) operation to support high-speed packet data applications. The challenge is to design a system that yields substantial throughput gain while causing only minimal perturbations to the existing standard. We are proposing a system that evolves features already present in the CDMA2000 IntroductionAlthough a fair amount of work has been done recently to enhance the packet data throughput of the downlink of code division multiple access (CDMA) systems, not many new concepts have emerged for enhancing the capabilities of the uplink. This is largely because most of the data application models presume the transfer of data to, rather than from, a mobile user. However, the applications scenarios are showing signs of change. Mobile users are increasingly likely to transfer data such as e-mail or digital images to the wireless infrastructure.In this paper, we describe some of the concepts embodied in a proposal that Lucent Technologies plans to introduce to enhance the reverse link (RL) data throughput of the future release of the CDMA2000* standard that is under development. 1xEV-DO-CDMA2000* evolution-data only 1xEV-DV-CDMA2000 evolution-data/voice A 2 IR-adaptive asynchronous incremental redundancy AWGN-additive white Gaussian noise BLER-block error rate BS-base station CDMA2000-third-generation evolution of IS-95 standard CDMA-code-division multiple access CDM-code division multiplex Ec/Nt-energy per chip to noise power spectral density ratio F-CPCCH-forward common power control channel FL-forward link F-UCACH-forward uplink control and acknowledgement channel F-USCH-forward uplink scheduling channel H-ARQ-hybrid automatic repeat request IS-95-second-generation CDMA standard MS-mobile station PCG-power control group PDF-probability density function RL-reverse link R-PDCCH-reverse packet data control channel R-SCH-reverse supplemental channel TCP-transmission control protocol TDM-time division multiplex Current RL Modes of OperationFor packet data services, the RL of a system conforming to the CDMA2000 3G1X standard operates in a slow scheduling mode. The actual scheduling latency is dependent on implementation choices at the infrastructure but can be up to a few hundred milliseconds. Mobile stations (MSs) request a schedule grant from the network. The network selects one or more MSs for data transmission and assigns data rates (307.2 kb/s or less) and duration(s) of transmission (20 ms or more). Additionally, MSs may transmit at a rate of 9.6 kb/s or lower without a schedule grant from the base station (BS).Only very limited advantage, if any, can be taken of instantaneous channel conditions, due to the implicit scheduling latencies.On the other hand, the RL of a system conforming to the 1xEV-DO standard (IS-856) allows MSs to transmit autonomously with the BS exercising supervisory control on the MSs as a whole, by advising them to adjust their data rates and transmit powers downward when the ...