Integrated rate and error control in variable spreading gain WCDMA systems

Optimal dynamic rate allocation among mobile stations for variable rate packet data transmission in a cellular wireless network is an NP-complete problem; therefore, sub-optimal solutions to this problem are sought. Again, interference calculation is non-trivial in the case of a packet-switched cellular CDMA network with heterogeneous traffic load in different cells. In this paper, a sub-optimal two-step dynamic rate selection procedure is proposed for uplink packet data transmission in cellular WCDMA (wideband code division multiple access) networks. A novel `mean-sense´ approach for inter-cell interference calculation is employed assuming homogeneous traffic load in the different cells. Two different error control alternatives for this variable rate packet transmission environment are presented and their performances are analyzed for three different channel models. The performance of the proposed two-step rate selection procedure is fairly close to that of the optimal rate allocation found through exhaustive search