The Study Of Interference Suppression Technique Of D2D Communication Underlaying Cellular Network

Since the data service integration into cellular communications services, mobile operators struggling to cope with large data traffic on the network. D2D(Device to Device)communication is a new and promising technology because it allows two UEs in proximity to communicate directly using the spectrum may be used by other cellular users in the same cell. However, D2 D and cellular communications sharing spectrum resources will produce mutual interference problems. In such systems, interference management is one of the most important problems, because improper interference coordination may cause the network to self-destruction. This paper focuses on the suppression of interference when using D2 D sharing spectrum resource with cellular users.This paper studies two scenarios to use D2 D interference suppression technology, one is multiple D2 D UEs sharing cellular spectrum in a single cell, and the other one is pre-coding interference suppression technology for multi-antenna D2 D.In the study of suppression technology for multiple D2 D UEs sharing spectrum resource with cellular UE. First, we studied the multiple D2 D UEs reuse the spectrum of only one cellular UE, the core idea of such this scheme is to ensure the QoS of the cellular UE,by constraint the interference D2 D UEs caused to the interfering base station equal. So that the transmission power of D2 D near the base station is small to reduce interference, when the distance between D2 D UEs and the base station is far, D2 D UEs may use higher transmission power, leading to higher communication rate. We ensure the communication quality of the cellular link in two cases, an instant CSI constraint or average CSI constraint, Under the instant CSI constraint, the UE and the base station need to update the channel information for each time slot, it will cause a lot of signaling overhead, while under the average CSI constraint allowing an outage for a certain probability, UEs only need update the average CSI information, reducing the signaling overhead. Our goal is to maximize the cell capacity. The disadvantage of the the scheme is that it can not make sure all the D2 D users to communicate, and thus the our scheme further consider D2 D UE can simultaneously reuse multiple orthogonal frequency spectrum of cellular UE, the benefits of doing so is to further improve the rate of D2 D, and improve the number of D2 D UEs which can communicate with each other.In the last part we study the joint pre-coding of D2 D UE and the base station to eliminate mutual interference in multi-antenna scenario, we study two solutions to solve the problem, one solution is to use a predefined codebook, this solution requires exchange of pre-coding information between the base station and the D2 D. In the second solution we proposes a distributed pre-coding scheme, which does not require exchange of information between the base station and the D2 D UE, and can get better performance at high SINR region.