Joint user scheduling and link adaptation for distributed antenna systems in multi-cell environments with imperfect CSI

摘要

This paper proposes a novel management algorithmfor distributed antenna systems (DASs) that exploits the spatialdiversity of the distributed architecture in order to schedule (overthe same radio resource) as many transmissions as possible withthe most appropriate modulation and coding schemes (MCSs).This goal is achieved by implementing a joint user scheduling andlink adaptation algorithm (including power control and adaptivemodulation and coding) that allows for an appropriate managementof intra-cell interference. The algorithm provides theoptimum set of scheduled users, the optimum serving nodes, thetransmit power levels, and the MCSs that maximize the capacityof the system. In comparison with conventional approaches,where the objective is to maximize the signal-to-interferenceplus-noise ratio (SINR) of each user, in this paper the targetis to satisfy a given SINR value that ensures the transmissionof the chosen MCS with a particular value of block-error-rate(BLER). To achieve this goal, an iterative optimization scheme isproposed in which the set of scheduled users, the power levels,and the MCSs are modified according to channel and interferenceconditions. A novel method for the calculation of outer-cell interferencein multi-cell configurations is also proposed. Imperfectchannel state information is used throughout the system-levelsimulation work. Simulation results show considerable gains interms of throughput and reduced power consumption per nodewhen compared to conventional systems, thereby making theproposed algorithm suitable for green energy solutions.