ON THE PERFORMANCE OF SDMA WITH SOFT DROPPING AND SINR BALANCING POWER CONTROL IN THE DOWNLINK OF MULTI-USER MIMO SYSTEMS

The application of Space Division Multiple Access (SDMA) to the downlink of future Orthogonal Frequency Division Multiple Access (OFDMA) mobile radio systems is a promising solution to achieve high spectral efficiency. Besides enhancing system capacity, Quality of Service (QoS) requirements must also be respected to ensure reliable communication. In this work, a new SDMA strategy called Soft Dropping Algorithm (SDA) is proposed, which is composed of an SDMA grouping algorithm, namely the Greedy CorrelationBased Algorithm (GCBA), a Joint Precoding with Soft Dropping Power Allocation (JP-SD-PA) strategy based on soft dropping power control, and an SDMA group size tracking mechanism. It is flexible and takes into account both capacity and QoS aspects. The proposed SDMA strategy is shown to provide average capacity gains of 10% to 30%, as well as SINR gains of 2 dB to 3 dB to 90% of the UTs in the system, compared to an SINR Balancing Algorithm (SBA).

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