Reaserch On Interference Management Based Transmission Scheme For Multi-antennas Uplink System

With the continuous development of wireless communication system, the contradictory between spectrum scarcity and its under-utilization becomes one of the critical problems limiting system performance. As the key to solve this problem, Multiple-input multiple-output(MIMO) techniques have attracted a lot of attention and received extensively research. MIMO can improve spectral efficiency significantly by spatial multiplexing. In addition, cognitive radio(CR) and heterogeneous cellular networks(HCNs) can improve the flexibility of the spectrum in use and increase spectrum reuse, thus also become effective means to improve spectrum utilization of. Exploiting MIMO in CR and HCNs can further enhance the system capacity and spectral efficiency. In this paper, the main work is as follows:At first, a transmission and scheduling scheme which can improve spectral efficiency is proposed for an infrastructured CR-MIMO system with multiple secondary users. With the cooperation between primary base station(PBS) and secondary base station(SBS), an interference alignment and cancellation(IAC) based signal processing procedure is designed. Not only the transmission rate of primary user(PU) is improved, the secondary user(SU) is also granted communication opportunity. The transmission difference of various spatial channels is exploited in SU scheduling. With the proposed scheme, interference-free concurrent transmission of both PU and SU is implemented. Spatial channel resources can be effectively utilized compared with a traditional interference alignment(IA) based strategy. Simulation results show that the achievable data for primary transmission is enhanced by cooperative signal processing at the SBS. With respect to the SBS, its data rate grows with an increasing number of SUs by exploiting the multiuser diversity gain.Then, an adaptive transmission mechanism exploiting is proposed for uplink transmission in HCNs including macrocell and picocell. This mechanism accounts for practical factors, such as path loss, relative locations of multiple cells, as well as transmit power difference of different mobile users. Based on the interference locality, we adopt both X channel and reduced X channel models. The base station side cooperation is exploited to design IAC based signal processing algorithms in both X channel model and reduced X channel model, respectively. Moreover, two reception schemes are adaptively selected in X channel model. Then concurrent uplink transmission of macrocell user equipment(MUE) and picocell user equipment(PUE) is realized. Simulation results show that the proposed scheme can significantly improve the achievable rate of MUE by exploiting cooperative reception of the data information carried by strong interference in X channel, whereas in reduced X channel, PUE and Pico e Node B(Pe NB) adopt signal processing algorithms suitable for their own transmission channel. Hence PUE’s rate is improved while the MUE’s could be well guaranteed.