Performance Analysis of Distributed Multi-Cell Coordinated Scheduler

Multi-Cell coordination or Coordinated Multi-Point (CoMP) schemes are seen as the next evolution of LTE-Advanced to yield a further improvement in overall system performance. In this paper, we study in detail the performance of one such CoMP scheme, namely Multi-cell coordinated scheduling (MuCCS). In our previous work, we have shown that the performance of MuCCS using a distributed "liquid cooperation cluster," where each cell coordinates with its nearest neighbors, out-performs a centralized scheme where the coordination is done over a small set of non-overlapping cells (either three cell or nine cells). In this work, we answer the question of whether there are any additional gains to be obtained by a centralized implementation, if the cooperation cluster is allowed to be arbitrarily large. We also quantify the additional performance gain obtained from allowing intermediate transmit power values besides just the binary on/off power values. Finally, we evaluate the performance of MuCCS when the eNodeBs are connected by a non-ideal backhaul, and devise a distributed MuCCS scheme that retains its advantage over a centralized coordination scheme even in the presence of a non-ideal backhaul. Overall, our results validate that additional high-complexity extensions of coordinated scheduling does not yield large gains over the distributed MuCCS scheme with "liquid cooperation clusters" and on/off power values. In this paper, we use the geometric mean of UE throughputs as the performance metric, and we motivate the rationale behind use of this as a single metric for performance comparison.