Research On In-Band Emission Interference Mitigation For D2D Neighbor Discovery Scheme In LTE-A Networks

Device to Device(D2D)communication technique is one of the main themes for the next generation wireless communication techniques. Compared with the traditional cellular communication which is formed between a user equipment(UE) and an evolved Node-B(e NB), D2D communication uses a direct link between different UEs. It's a technique with high spectrum efficiency and low power consumption, which can also offload the e NB's traffic and realize communication between UEs even out of cellular network coverage. In the standard organization, 3rd Generation Partnership Project(3GPP), there is an ongoing discussion to adopt the D2D communication in current Long Term Evolution Advanced(LTE-A) system. D2D in LTE system is mainly used in public safety using direct communication and commercial services using proximal device discovery.D2D neighbor discovery is a fundamental aspect of D2D proximity services, allowing discovery user to advertise its presence and/or discover others in its neighborhood. Introduction of the D2D discovery into LTE-A network brings some impacts to existing cellular operation by the in-band emission due to the coexistence of the D2D discovery and physical uplink on a given carrier. In-band emission interference will influence the reception of PUCCH(Physical uplink control channel) signal, which is highly related to the downlink HARQ(Hybrid Automatic Repeat Request). Therefore, if the in-band emission interference has not been well handled, the system output will decrease. To solve the problem, resource grouping and OLPC(Open Loop Power Control) is proposed. By resource grouping, performance of D2D discovery can be maintained, but SINR(Signal to Interference and Noise Ratio) of part PUCCH signals degrade, while the second method would improve all SINR of PUCCH with D2D discovery performance decreasing.In this thesis, we studied the basic procedure of D2D discovery, combining the suggestion of 3GPP to optimize the D2D discovery procedure, which guaranteed the discovery performance. Then a resource grouping and partial UEs OLPC based scheme is proposed, which is designed to overcome the existing shortage of current methods to handle in-band emission interference. This scheme is based on the discovery procedure mentioned above. UEs are divided into two groups according to their downlink RSRP(reference signal received power). Meanwhile, the resource is divided into two groups in time division manner. Since the in-band emission interference caused by D2D UEs with high RSRP is more serious, OLPC is necessary. The proposed scheme can improve the PUCCH SINR and degrade the in-band emission interference with less D2D discovery performance loss.In the end of the thesis, results simulated according to the parameters given by 3GPP show that the scheme is rational and effective. This work provides a strong theoretical support for the application of D2D technology in the future mobile communication system.