| LTE is a phase development after the third generation mobile communication, with OFDM and MIMO as its core technologies during wireless evolution. In order to realize the ruled indicators of the ITU IMT-Advanced,3GPP starts the backward compatibility of LTE evolution process. The key technologies, like carrier aggregation, coordinated multipoint transmission and enhanced inter-cell interference coordination, are called LTE-A as a whole. The successful selection and residence of mobile terminal for service cell are the premises for cellular mobile communication network to provide business service to users, so cell selection and reselection are significant for the communication system.In September 2009, the heterogeneous network technology was proposed by 3GPP in the process of the standardization of LTE-A, since then LTE-A heterogeneous network became a research hotspot. Due to the introduction of low power nodes, that transmission power are far lower than the macro-station in heterogeneous network, which leads to covering small area by low power nodes, so the number of the users that select the low power nodes as a service station is small, and the cell division gain fail to maximize. To extend the low power nodes’coverage and improve the priority of selecting low power nodes, some of the enhanced cell selection and reselection scheme were proposed in LTE-A heterogeneous network in 3GPP conference research and discussion, especially the RE algorithm which is put forward by qualcomm discussed a lot.Two enhanced cell selection and reselection algorithms were proposed to achieve the expansion of the coverage area of low power nodes and to improve the priority of selecting low power nodes in LTE-A heterogeneous network in this paper, shunt the macro load by low power nodes further, and achieve the purpose of improving system performance ultimately. Those algorithms select a cell that ensure the quality of their and produce low interference to other cells, instead of the tranditional cell selection and reselection algorithm which select the cells with the strongest reference signal received power as a serving cell. Conducting system level simulation over system simulation platform in this paper, we compared the proposed algorithm which based on SINR queue and the traditional algorithm, and on the base of the simulation, the comparison between selection algorithm which based on SINR queue and the selection algorithm based on interference alignment are also simulated. The simulation results show that the proposed algorithm based on SINR queue cell selection and reselection algorithms and cell selection based on interference alignment algorithm all can expand the coverage area of the low-power nodes, and improve the priority of the user selecting low power nodes, in terms of the system gain, SINR queue algorithm as equvilent with RE algorithm, while SINR queue algorithm avoids most of the problems of RE algorithm, for instance, there is no uniform standard in the bias value and with the bias value increasing the users in the expand area of low power nodes coverage, which SINR was deteriorated; we can also see from the simulation results, compared with the SINR queue cell selection algorithm, the cell selection based on interference alignment algorithm improved the system performance gain about 45%. And after coordinating the inter-cell interference coordination technology, which can improve the system throughput, the throughput of the edge users also improved effectively at the same time. |
