Research On Application Performances Of LTE-Advanced Relay Technology

With the increasing development of mobile communication technologies and the increasing demand of users for better communication quality, wireless communication system shows a trend that advances to be a mobile, broadband and IP-based system. In this situation, ITU(International Telecommunication Union) put forward high-er requirements for mobile communication system, IMT-Advanced (International Mobile Telecommunication-Advanced),also known as The Fourth Generation Mobile Communication(4G).ITU issued an invitation to submit candidate technologies for IMT-Advanced to all over the world in January 2008.As the most concerned standard for broadband mobile communication technology,3GPP LTE(Long Term Evolution) has already possessed obvious features of 4G technology by introducing a number of key technologies of next generation mobile communication. However, LTE does not fully meet the requirements of IMT-Advanced. To anticipate the invitation from ITU, based on the work on the first release of the LTE,3GPP proposed LTE-Advanced as the further evolution of LTE. One of the goals of this evolution is to fulfill and even surpass all the IMT-Advanced requirements on capacity, data rates, latency, spectrum efficiency and low-cost deployment, etc.In order to reach the requirements for the evolution of LTE,3GPP proposed some technology components in the LTE-Advanced system. One of the potential key technology components is the relay technology. Relay technology can effectively increase data rates, extend the coverage area, expand the system capacity, improve spectrum efficiency, combat fading, enhance the system robustness, etc. Also, it is able to deploy the wireless cellular network in a cost efficient manner and thus cut down CAPEX (Capital Expenditure) and OPEX (Operating Expense). Relaying is considered for LTE-Advanced as a tool to improve e.g. the coverage of high data rates, group mobility, temporary network deployment, the cell-edge throughput and/or to provide coverage in new areas.In this paper, development and technical background of 3GPP LTE and LTE-Advanced systems, relay technology and its application such as relay types, relay schemes, relay scenario, etc, are introduced firstly. Then, performances of relay technology introduced in the conventional wireless cellular network and performance improvement are studied. In the fourth chapter we analyze the symbol error rate (SER) performance of multi-relay decode-and-forward (DF) cooperative communications. In the analysis, we consider that the communication channels are assumed to experience generalized Nakagami-m fading and all the channel links are mutually independent. Chapter 5 analyzes the Call Dropping Probability (CDP) performance based on the variation in received signal power over distance due to path loss and shadowing. The results show that under certain conditions relay technology offers tangible performance improvement benefits.