Key Technologies Of Cooperative Communication

Fundamental research has demonstrated the great potential of cooperative communication in handling inter-cell interference (ICI). It will continue to be the crucial technology to managing the quite severer ICI incurred by the ultra denser network deployment in The5th Generation mobile communications (5G). In this context, this dissertation studies the cooperative communication theory and standardization. Particularly, with respect to the three basic problem of cooperative communication, performance of cooperative communication, how to cooperate and design of cooperative communication in practical application, we investigate the achievable capacity of cooperative communication in terms of power allocation, adaptive theory, key technologies in standardization and evolution from The4th Generation mobile communications (4G) to5G for cooperative communication. The main work and achievements are stated as follows:(1) Power allocation for cooperative broadcast channel with shared channel quality indicatorConsider cooperative broadcast channel with N (N≥2) cooperative TPs (each equipped with K antennas) and K users (each equipped with single antenna). Assume that the cooperative TPs can share the data information intended for different users and CQI (channel quality indicator) in real time. Zero-forcing beamforming is adopted for all the cooperative TPs. We derive the closed form expressions of optimal cooperative power allocation to maximize the sum capacity. Based on the derived solution, cooperative power allocation algorithm is further presented. Numerical results show that the proposed optimal cooperative power allocation scheme provides obvious gain over the non-cooperation case.(2) Optimal cooperative water-filling power allocation for OFDM systemConsider a cooperative OFDM system consisting of N(N≥2) TPs and Kc orthogonal subcarriers. To maximize the sum capacity, we get the conclusion that at most one subcarrier should be transmitted together by2or more than2cooperative TPs, and each one of remaining Kc-1subcarriers should be transmitted at most one cooperative TP respectively. Furthermore, optimal cooperative water-filling power allocation algorithm is proposed and closed form expressions for the optimal power allocation is achieved under certain conditions. Numerical simulation demonstrates the performance of the optimal cooperative water-filling scheme.(3) Adaptive modulation for Dynamic point selection (DPS)/Dynamic point blanking (DPB)Considering a typical CoMP system consisting of3cooperative TPs, all possible DPS/DPB schemes can be divided into three types. We present an analytic model to perform non-adaptive, ideal adaptive and non-ideal adaptive with imperfect CSI modulation for all kinds of DPS/DPB schemes, where a target bit error rate is set. The contributions are:1) Derivation of PDFs of SINR for all kinds of DPS/DPB based on an assumption of CQI definition.2) Derivation of conditional PDF of SINR on reported imperfect CQI for all kinds of DPS/DPB.3) Proposing loading algorithms for all kinds of non-adaptive, ideal adaptive, adaptive with imperfect CSI modulation DPS/DPB.4) Derivation of the closed form expression of average spectral efficiency for all kinds of ideal adaptive modulation DPS/DPB. Although it’s for a CoMP system consisting of three TPs, it’s not difficult to extend the analytic model to a general K-TP (K≥3) case.(4) Key technologies of CoMP in LTE/LTE-AGive full introduction and analysis of key technologies of CoMP standardization in4G, including downlink CoMP technology, CSI report, interference measurement, reference signal design, control signal design, uplink CoMP technology and so on. We also focus on the CSI report for joint transmission (JT) and common reference signal (CRS) pattern related control signaling. We propose a CSI feedback scheme for JT with better balance between feedback overhead and obtained performance gain, and propose a CRS pattern related control signaling approach which supports more flexible CRS pattern configuration under the same signaling overhead.(5) Evolution from4G to5G for limited feedback CoMP systemWe review the state of the art in limited-feedback CoMP systems research. We first give an overview of recent related work in feedback-based coordinated transmission and then provide a performance analysis of typical feedback schemes and sensitivity to the CSI delay. Furthermore, since mobile systems evolving to5G have to bear a huge quantity of irregularly distributed wireless data traffic, cooperative communication will be more widely applied not only to address the ICI but also to improve the system resource utilization and data rate. We summarize the recent trend on5G network architectures enabling the novel CoMP features, and we discuss the potential evolution directions of limited-feedback approaches motivated by CoMP development toward future5G networks.