Research On User Assignment Algorithm For Heterogeneous Wireless Networks

Heterogeneous network technology is one of the key technologies of the long term evolution(LTE-advance) set by the third generation partnership project(3GPP).In heterogeneous network, emerged a large number of "village edge area" due to the deployment of a variety of small power stations. According to downlink strongest receiving signal to choose cell, users tend to access base station with higher transmission power, lead to base station overload, but micro base station didn't get good use. This paper mainly studies the heterogeneous network downlink transmission system, the edge of the user community choice allocation algorithm, aimed at solving the distribution of the cell edge user problems in heterogeneous network, effectively improve the quality of services at the edge of the user.First introduces the network characteristics of heterogeneous network, analyzes the load balancing problem and inter cell interference, and the existing problems and deficiencies in the traditional cell selection algorithm. The traditional cell range expansion(CRE) cell access algorithm is improved, and proposes an edge user selection algorithm, the edge users through the sender precoding restrain interference,improve the user receives a letter to noise ratio. Based on the current residential users,dynamic adjusting the small area edge user reference signals to add the bias, avoid edge users accessing to too heavy loaded cells.Heterogeneous network during base station deployment within range of the base station, inevitably appear different overlapping coverage of small area. According to this hypothesis, the paper based on the maximum Reference Signal Receiving Power(RSRP) community access algorithm was improved, according to the current cell user distribution, modified the value of the downlink reference signal received by the user,the overlapping coverage cell users tend to access its pico light load cell adjacent.Finally, the improved CRE method and selection algorithm based on RSRP are verified by MATLAB simulation, verify the improved cell selection algorithm, for different heterogeneous network scenario, the edge user distribution known algorithm can effectively reduce the macro cell load, balance the different pico cell load, improve the light load micro cell network throughput, and resource utilization.