Mode Selection And Interference Coordination In The Hybrid D2D And Cellular Network

Many technologies, such as relay, CoMP and carrier aggregation, have been introduced into the IMT-Advanced system, leading to better performance than the traditional cellular network on both coverage and quality. However, due to the limitation of the cellular infrastructure, there is still much space for improving either network capacity or spectrum usage. D2D, which is short for the Device-to-Device communication, is capable of establishing a direct wireless link between the transmitter and receiver and thus providing data transmission with low power-consuming and high speed. Early studies have indicated that both the transmission rate and coverage are enhanced with D2D reusing cellular resources.While D2D brings benefit to the hybrid network, it also produces several novel challenges. The first is that since there exist more options of the operating mode for each terminal, extra regulations are essential to determine the optimal mode. Secondly, the diversity of resource sharing manners makes the wireless environment more complicated. Unless the interference is controlled effectively when D2D reuses the cellular bands, it may cause unpredictable harm to both cellular and D2D communication. Hence it is under much discussion that how to coordinate the interference in the hybrid network.In this paper, the mode selection and interference coordination in the hybrid network are studied, where the D2D communication is assumed to share the uplink resource with cellular user. The definition of mode selection is first introduced, and the mode selection procedure and interference coordination mechanism are then investigated among different scenarios. A distance-dependent algorithm is proposed for the single cell environment, aiming at selecting the optimal transmission mode with the overall capacity maximized and QoS of cellular user satisfied at the cost of nearly the least essential information for decision-making. The simulation results prove that the novel algorithm tends to the theoretical optimal results based on merely a few parameters instead of traversal analysis, which is much more significative in practical application than the traditional ergodic way. On the other hand, the heterogeneous network of D2D and LTE-Advanced in a multi-cell environment is further considered. In order to choose the optimal operating mode of D2D more independently and precisely, a semiautonomous procedure is proposed, intending to maximize the system capacity as well as guaranteeing QoS of cellular users. The simulation results prove that assisted by the cellular network, the proposed procedure achieves better performance compared with either the local-assisted scheme or the non-assisted one.