Research On Decode-and-forward Relay Technology In LTE-advanced System

Based on the theory of LTE, LTE-Advanced technology comes up as a newgeneration of mobile and cellular communication system. LTE-A can satisfy themutiple increasing high rate with better quality of service (QoS) and high capacity.Therefore, LTE-A system should enjoy a better transmission rate, more coveragearea, higher throughput and higher cell edge customers’ transmission rate in themobile communication system. Many operators pay more and more attention toadvantages of the wireless relay, such as lower cost and lower power.Communication standards such as WIMAX (Worldwide Interoperability forMicrowave Access) and the3GPP (The3rd Generation Partnership Project) havelucubrated the wireless repeater technology. With the superiorities such as tinyvolume, light weight and easy to expand, the wireless relay have became into apopular issue in the field of communication technology. It can effectively increasethe cell coverage area, system performance, and the throughput of the whole system.By estimating the performance of the relay technology based on the systemlevel simulation, this paper consists of four main parts: First, according to thesimulation scenario and the simulation parameters in the case of3GPP protocols, theLTE-A system modeling includes the next eight steps:(a) the building of topologystructure;(b) base station distribution;(c) relay distribution;(d) users distribution;(e) configuration of the base station parameters;(f) relay parameters;(g) the systemchannel modeling;(h) the calculation for system interference. Second, according tothe interference coordination scheduling technology, this paper uses the staticfractional frequency reuse for resource allocation and gets the simulation result.Third, this paper puts forward three different relay deployment schemes accordingto the existing methods, namely one relay per sector, two relays per sector and fourrelays per sector. For one relay per sector, the distance from relay to the base stationis5/12×ISD (Inter-site Distance). For two relays per sector, the distance from relayto the base station is5/12×ISD and the angle between the two relay is40°. For fourrelays per sector, the distance from three of the relays to the base station is5/12×ISD and the distance from another relay to the base station is1/4×ISD. At last,by using the theory above, this paper discusses the relay performance with the ratioof two-jump users and the throughput and the signal to interference plus noise ratio(SINR) for Case1(city) and Case3(suburb or rural) scenario, respectively. Then forthe Case3scenario, this paper discusses the performance of the system for different relay transmit power.The simulation results show that the wireless relay technology can provide abetter throughput and increase the cell edge customers’ throughput significantly.Moreover, with more deployed relays, the number of two-jump users will augmentand the performance of the system will be enhanced. However, with highertransmitting power, SINR of the cell edge customers and the throughput willincrease together, but the high transmitting power will make a large interference tosingle-jump users.