Dynamic uplink coordinated multi-point scheme based on Range Expansion in Heterogeneous Networks

In 3GPP Long Term Evolution (LTE) Heterogeneous Network (HetNet), the macro Base Station and the pico Base Station (BS) have very different transmit powers. So the traditional cell selection makes some users connected to a macro BS although they are geographically closer to a pico BS. These users would create severe uplink (UL) interference in HetNet. Range Expansion (RE) technique is one saving grace that could partly mitigate the UL interference problem. However, it may simultaneously bring new downlink (DL) interference. In this paper, firstly an Uplink Interference Identification Scheme based on Range Expansion is proposed to identify the main UL interference source accurately. Then a dynamic UL Coordinated Multi-Point (CoMP) scheme is applied to the main interference source to ease the UL interference in HetNet. The proposed CoMP scheme dynamically chooses coordinated BSs for an allocated user itself specifically. And the CoMP scheme has no direct relation with DL, which means that it would not bring new DL interference, compared to RE. Simulation results indicate that the dynamic UL CoMP scheme can bring nearly 25% gain to the average user Signal to Interference and Noise Ratio (SINR) and nearly 22% gain to the average user throughput.