A novel double-threshold user division method based on channel isolation and scheduling for downlink CoMP

Coordinated multi-point(CoMP) is regarded as a key technology in LTE-Advanced to eliminate the inter-cell interference and improve the user throughput, especially in cell edge. Traditional single-threshold coordinated user division, irrespective of whether it is based on distance or other metrics, has a potential problem whereby channel state variations lead to frequent user mode changes between coordination and non-coordination states, placing undue constrains on the system backhaul consumption. On account of such weakness, a novel user division method based on double-threshold is proposed in this paper to reduce the user handover with static clustering. As a result, a user with coordination has a relatively stable status between the two thresholds. The judging threshold adjusts in line with the user´s last transmitting mode over the time. Furthermore, Zero-forcing precoding and water-filling power allocation are employed. Numerical results show that the proposed algorithm provides user throughput improvement and achieves a good balance between system throughput and backhaul overhead, providing even more benefits especially in scenarios where the channel state changes rapidly.