Self-organizing distributed inter-cell beam coordination in cellular networks with best effort traffic

Interference reduction, cooperation and the performance of cell-edge users are important issues in next generation cellular systems. Based on previous works for single-input single-output (SISO) systems, we propose a novel interference reducing self-organizing coordination scheme for a multi antenna OFDM system with space division multiple access (SDMA). The proposed Virtual Subband Algorithm (VSA) tries to maximize the overall network utility by adjusting transmit powers on a per beam granularity and leads to a soft fractional frequency reuse. It uses only small additional information exchange between sectors and infrequent additional long-term feedback. Although reducing interference, VSA follows a completely new approach by having all beams switched-on all the time. Simulations show that in static settings compared to a non-cooperative, highly opportunistic, greedy scheduling scheme, VSA achieves significant gains both in the performance of cell-edge users and in the overall system performance, defined in this paper as the geometric average of user throughputs. Moreover it is shown that cell-edge users benefit even in fast-fading cases, although a gain in system-wide performance cannot be guaranteed.