Wireless Relay Cooperative Network Resource Allocation

With the development of wireless technologies, wireless systems is evolving to-wards the standard of high transmission speed and high service quality. Since the time of the second generation of wireless systems, to the third generation and even the fourth generation, the network architecture and transmission technologies of wireless systems are constantly upgrading. As the core technology of 4G communications, Orthogonal Frequency Division Multiplexing Access (OFDMA) has been widely studied. At the same time, cooperative communication and relay communication technologies have been proposed. In a cooperative communication system, a user can transmit data with the help of other users or fixed terminals. Cooperative transmission technology can effectively increase the spatial diversity, expand network coverage and lower terminal transmit power. This novel technology has been the extensive industrial and academic attention.This thesis focuses on the three themes of the performance analysis of relay trans-mission, relay node location selection and allocation of resources for OFDMA relay cell, and research the relay network resource allocation problem from the dimensions of time, frequency, space.Generally, relay systems use time-divided or frequency-divided channel for signal transmission. The paper derives the upper and lower bounds of the channel capacity from the basic parallel relay channel, then applies the results to Gaussian orthogonal re-lay channel. Then take the frequency-divided channel for example to study the impact of resource allocation to the channel capacity, get the expression of optimal resource allocation under different conditions. Moreover, the impact of the relay link status on the system capacity is also analyzed and simulated.By placing the relay nodes in the cellular cells to assist communication, the sys- tem capacity and transmission quality can be effectively increased, as well as extending the cell coverage. Based on the continuation of existing research, this paper studies how relay node location selection improves the system performance,under the critiria of im-proving the transmission performance of cell edge users and expanding the cell coverage area. Also, a detailed system simulation as well as the reasonable suggestions are given, for practical application of relay communication.When relay technology melts with OFDMA technology, the cellular networks will be able to access data faster than the current transmission rate as well as to achieve a better user resource allocation results, so some relevant studies have started in recent years. However, these studies usually focus on some simple structure (for example, the case of only one receiver), or on centralized resource allocation. This paper studies a centralized greedy resource allocation scheme and a semi-distributed resource alloca-tion scheme in an OFDMA cell with multiple relay nodes and multiple receivers, in order to achieve the transmission rate and equity balance. Compared with the tradi-tional resource allocation scheme, the proposed schemes seems to be effective resource allocation schemes while maintain the low complexity.