Research On The Key Technologies Of Cooperative Relaying Network For Next Generation Wireless Communication System

With the development of wideband communications technology, the requirement on the quality of mobile communications is increasing. Recently, cooperative techniques can be used to enhance many key performance figures of a wireless communication system, being perhaps data throughput, network coverage, quality of service as well as spectral and power efficiency being the most relevant ones. Moreover, relay-based deployment in cellular concepts will play an important role in the cost effective provision of very high data rates, and it is one of the key technologies for the future 4G cellular networks. Therefore, there has been an increasing interest in the infrastructure-based wireless multi-hop networks in academia, industry, and standardization bodies. This dissertation focuses on the key techniques in wireless relay systems, and gives a thorough and comprehensive study on the coded cooperation with multiple relay system, Power allocation and Best-relay Positioning of Incremental selection amplify-and-forward relaying (ISAF), the system level evaluation for LTE-Advanced Relay and clustering algorithm for two-hop integrated cellular and Ad hoc relaying networks.Firstly, based on the classical coded cooperation protocols and the applications in system, this paper proposes a generalized distributed turbo codes (DTC)-based coded cooperation protocol for two-hop relay networks with an arbitrary number of relays. This scheme aims at achieving improved diversity and balance over the classical coded cooperation method in Rayleigh fading channels. We derive a finite range single integral solution for the outage probability in Rayleigh fading channels, and the diversity gain is achieved. We also develop a closed-form expression for the pairwise error probability (PEP), a tight upper bound for the bit error rate (BER) using DTC, and the analytical upper bounds are validated with simulation results. Our results demonstrated the efficiency of the proposed protocol in comparison with other re-transmission cooperative strategies, and this attribute to the incremental redundancy coding gain. Moreover, in order to improve the performance of the LTE-Advanced Relay, we also propose a coded cooperation scheme for the Type?Relay of LTE-Advanced.Secondly, Because Incremental selection amplify and forward relaying (ISAF) has the best performance of outage probability among relaying strategies and has been identified as the best protocol. This paper proposes to jointly optimize power allocation (PA) and best-relay position based on cooperative diversity for ISAF in order to minimize outage probability. The closed-form solution to the adaptive allocation algorithm based on high signal-to-noise ratio (SNR) approximation of outage probability is presented, assuming maximum ratio combining (MRC) at the destination. Simulation results have shown that the system performance of outage probability with the proposal outperforms the equal PA algorithms, and much less power is needed to achieve the same outage probability at the same effective rate. The power saving can be as much as 9 dB compared to the equal power allocation scheme.For the next generation of cellular networks, relay-based multi-hop cellular deployment concept has been considered as a potential air interface technology by LTE-Advanced. A system simulation platform is established to evaluate the system performance of LTE-A relay. Many important research topics, such as site planning algorithm, MU-MIMO scheme, and backhaul link enhanced technology, can be evaluated through this platform. To solve the problem of bottleneck in backhaul link, Some single user MIMO scheme and multiple user MIMO are used and compared, such as EBB, BD, and SLNR, etc. Simulation results show the MU-MIMO scheme is effective in LTE-A Relay backhaul link. Moreover, in order to improve the performance of the cell, this paper proposes a PF scheduling algorithm to balance the capacity of the backhaul link and access link.Finally, this paper proposes two clustering algorithms for Integrated Cellular and Ad hoc Relaying systems, whose objective is to increase the next generation wireless cellular network throughput and further improve the system performance. In this cellular system, we consider all the available users are divided into two groups. One is the super group which locates in the cell central region, and another is the regular group which locates in the cell boundary. The super group is served by Base Station (BS), and the Mobile Stations (MSs) locate in the cell boundary are served by the cluster-head (CH) which is elected from the regular group. Simulation results show that this scheme can bring improved SINR distribution, higher system throughput, and it also can increase the data rate at the cell edge.