Research On Relay Interference Coordination Technology In LTE-Advanced System

Based on the LTE technology, LTE-Advanced technology has become a newgeneration of mobile system to meet the increasing demand of data rate and to be anadvanced technology competing with Wi-MAX. There is a need for an increase inthe node density to further improve system throughput, site coverage and peak datarate. Thus, relay has been a key technology for LTE-Advanced systerm, with theconsideration of both cost and performance improvement. However, the increase inthe node density leads to interference problem as well. How to get a trade-offbetween system performance and interference has become an issue that requiresserious attention.The paper suggests a set of themes based on interference coordination to solvethe interference issue of in-band Type I relay and out-band Type Ia relay systems.First, according to3GPP protocols, we make a model of LTE-Advanced system withrelays, which includes multi-site topology, base station placement, relay siteplacement, mobile station placement, base station parametres, relay site parametres,mobile station parametres and channel model. Second, we find out the optimumtheme among existing relay site planning proposals for each system scenarios viabasic system simulation. For both in-band Type I relay and out-band Type Ia relay,there should be only one relay site in each cell considering that Case1scenario hasa smaller inter-site distance and higher inter-site interference. In Case3scenario, itis not as sensible as in Case1, so placing two relays in each cell is the best choice.At last, the paper propose MBSF theme for Type I relay and ABS theme for Type Iarelay to mitigate inter-cell interference and improve system performance. Accordingto the blank rate of frames by3GPP, MBSF and ABS subframes are placed amongframes uniformly. In the MBSF theme, there is one MBSF subframe among fivecontinuous subframes, whilt in the ABS thems, there are one or two ABS subframesamong eight continuous subframes.The proposed MBSF and ABS themes are proved to have performanceimprovement of different degree under Case1and Case3scenarios via system levelsimulation. In Type I relay system, MBSF theme perform quite well in Case3scenario and gain a large system improvement comparing to Case1scenario. InType Ia relay system, ABS theme with a blank rate of1/8is no doubt the optimalchoice in Case1scenario, while under Case3the ABS themes have a similarperformance.