Relay Technology Applications In The Next Generation Cellular Mobile Communication Network

As protocols for LTE (Long Term Evolution) work finished, its Evolution:LTE-Advanced (LTE-A) relevant technologies are being discussed on and on. LTE-A system has proposed that the downlink peak rate should be more than 1Gbit/s and uplink peak rate be more than 500Mbit/s following the performance requirements. In order to guarantee the transmission rate, we can only dramatically reduce the cell coverage area, and increase the number of cells. However, the public is becoming more and more concern about the radio radiation, even to maintain the existing sites is difficult, to increase the number of cell sites is not reality. In addition, the cost of the systems will increase as the number of base station rise. People are doing more and more researches on wireless relay technologies because deploying wireless relay station can increase the system capacity and enlarge the cell coverage without any increase in the number of base stations.Relay works that the Base Station does not directly transmit signals to the User Equipment (UE), but first send to Relay Station (RS), then the Relay Station transmit it to UE. The uplink is similar with the downlink. Relay is an important candidate technology to be adopted in the LTE-Advanced system. On the one hand, LTE-A has proposed high system capacity requirements; On the other hand, the big bandwidth to ensure the high capacity can only be reached in high frequency, while path loss and penetrates loss in such a high frequency band is bigger, it is difficult to achieve better coverage. In the traditional LTE system, besides that we can use technologies such as MIMO (Multiple Input and Multiple Output), OFDMA (Orthogonal Frequency Division Multiple Access), Smart Antenna and Diversity to enlarge the coverage, we can also use Relay technology and distributed antenna technology to improve the system coverage. What is more, if the relay is deployed in the coverage of the Base Station coverage, it can also improve the system capacity.In the standardization process of relay technology, I actively follow up my research with it. While relay technology is applied in cellular mobile communication system, we adopt the MIMO technology in the backhaul link to promote the whole system capacity and solve the bottleneck problem caused in backhaul link. At the same time, we verified the performance of high order modulation when the backhaul link condition is good enough, and the high order modulation can be selectively adopted to solve the bottleneck problem in the backhaul link. What is more, the scenario that the relay is used in handover is analyzed and a handover scheme is designed to decrease the outage probability caused by handover in relay network.