Optimum rate allocation for two-class services in CDMA smart antenna systems

Transmission bit rates are optimized for two-class traffic in variable spreading gain codedivision multiple-access systems with antenna arrays. In an array antenna system, the interference levels experienced by the users belonging to different beams are not the same. Thus, it is not efficient to allocate the same rates to all the data users even though they belong to a cell. Considering this, an optimum rate allocation scheme is proposed for delaytolerant data users. Additionally, we also propose the optimum rate allocation scheme for voice and data users when a packet scheduling scheme is considered. Numerical results show that, in array antenna systems, the proposed schemes considerably outperform the conventional scheme designed for omniantenna systems.