Hierarchical SIR and rate control on the forward link for CDMA data users under delay and error constraints

In this paper, we study the signal-to-interference ratio (SIR) and rate con trol for code division multiple access (CDMA) data users on the forward lin k under average or peak power constraints. The quality of service (QoS) for data users is specified by delay and error rate constraints as well as a f amily of utility functions representing the throughput and fairness among t he data users. It is found that the optimal SIR and rate control algorithm has a hierarchical structure which can be easily implemented in a distribut ed manner. The SIR targets can be adjusted independently by the mobiles usi ng information specific to the individual users. The data rates can be adju sted jointly by the base station based on limited feedback from the mobiles . We also propose a two-level iteration algorithm for both the mobile and t he base station to efficiently compute the SIR and data rates. Our results show that a flexible tradeoff between total system throughput (sum of rates achieved) and fairness (similarity in data rates) can be achieved by choos ing appropriate utility functions used in this scheme.