Data rate control based on extended medium access control channels for CDMA high-speed data services

Abstract

The cdma2000 1xEV-DO system provides bandwidth-efficient and high-speed wireless internet services to mobile subscribers. The standard is considered as an evolution of cdma2000, and suitable for packet data services that are characterized by asymmetric data rates. On the reverse link, a traffic channel is assigned to each access terminal, and the data rate is determined by a reverse activity bit (RAB) from the base station and a probabilistic rate control model. The reverse link capacity of 1xEV-DO has been discussed intensively in the literature, but there has not been enough research on the reverse link rate control. Therefore, this dissertation proposes an analytical system model for the rate control. Comparison with simulations shows that the proposed analysis model provides a good analytical framework for modeling the 1xEV-DO rate control. In addition, the reverse link performance is examined for various system parameters. We can see that there is a trade-off between the overload probability and the reverse link throughput, and the system performance is highly dependent on the system parameters. The IxEV-DO rate control causes the traffic load to fluctuate around a certain threshold. The degree of fluctuation depends on various system parameters, but it is difficult to find appropriate system parameters for stable operation. Moreover, there is no reliable means of suppressing excessive fluctuations of traffic load. This dissertation therefore proposes two enhanced rate control schemes that improve upon the conventional one with respect to the overload probability and the reverse link throughput. In the first proposed scheme, the base station divides the reverse traffic load into four classes, and broadcasts an associated 2-bit symbol to all access terminals. The 2-bit symbol is carried on the extended reverse activity (ERA) channel, and informs the access terminals of the traffic load status more precisely. The ERA channel can be easily realized by the cur...