Optimal discrete spreading factor determination for uplink resource allocation in multiservice UMTS and HSUPA networks

Attention to resource allocation algorithms for multiservice Code Division Multiple Access CDMA networks has focused on algorithms maximizing the uplink aggregate throughput. In the present paper we address the problem of the joint power and spreading factor (SF) allocation to non real-time (NRT) terminals on the uplink, once real time constraints are satisfied. An optimal algorithm is proposed, that maximizes the uplink aggregate NRT throughput while allocating SF in a set of discrete values, as those used in 3G systems. It is shown that the results obtained are close to the theoretical upper bound, and that thanks to power control, more NRT services can be admitted. Compared to Univeral Mobile Telecommunications System (UMTS) services, the High Speed Uplink Packet Access (HSUPA) services increase the aggregate uplink NRT throughput, especially at low cell´s load, and decrease the interferences generated at the base station level at high cell´s load. In return, the number of simultaneously served NRT services is significantly lower.