Interference Coordination And Resource Allocation For D2D System

Advanced computer techniques such as internet and cloud computing greatly enrich our daily life, and have become fundamental demand of the public. The significant development in large scale integration technology makes the mobile devices so powerful that they are fully capable of most internet services. The data carried by cellular networks are no longer simple media like voice or short messages, but complex multi-media such as video and other kinds of data. These changes challenge the capacity of the current cellular networks. The limited frequency resources are the main bottleneck of the development of cellular networks. Increasing the spectrum efficiency is one of the most significant ways to improve the capacity of cellular networks. Techniques that can enable spatial reuse attract much attention in recent years, as they can greatly increase the spectrum efficiency without too many costs. Among them, the Device-to-Device (D2D) communication makes use of the proximity of two devices that need to communicate with each other, enables direct communication between them. Since the two devices are close to each other, they can experience better services by D2D than being relayed by the infrastructures known as base stations (BS). The transmit power can be decreased. The most attractive benefit of enabling D2D in cellular networks is that the D2D communication may reuse the radio resources of the cellular users so as to increase the spectrum efficiency. Therefore, D2D communication becomes one of the hot topics in cellular network research.We firstly study the interference management in D2D communication underlaying cellular networks. The co-channel interference between D2D users and cellular users should be controlled if spatial reuse is applied. By properly controlling the transmit power of D2D users and optimizing the resource allocation, D2D reusing the resources of cellular users can introduce significant benefit while maintain certain quality of services (QoS) of all users. We propose a partial location based interference mitigation strategy to deal with the interference in a single cell scenario. The strategy is designed based on the large scale pathloss channel model. We calculate an interference limited ring in which the cellular users should not share the resources with D2D users, otherwise the QoS defined by outage probability of users cannot be satisfied. The proposed strategy only need one dimensional distance information of users and has low computing complexity. We further improve the former idea by considering the fading channel model and deal with the interference mitigation issue in D2D communication underlaying multiple fractional frequency reuse cells and propose two novel concepts, namely accessible region and reusable region.The D2D communication underlaying heterogeneous cellular networks where small cells are deployed is considered in the second place. The small cell technology also takes the advantage of user proximity and enables spatial reuse. Low power core network access points (APs) can be de-ployed in hot spots or blind areas to provide cellular services. Future cellular networks are devised to be heterogeneous. The resource optimization in D2D communication underlaying heteroge-neous networks is considered in the first place. D2D users have five alternative communication modes, namely macro cell resource reuse mode, small cell resource reuse mode, dedicate mode, macro cell mode and small cell mode. We also study the energy efficiency based resource alloca-tion and mode selection problem. The resource optimization for the cooperative design between D2D and small cells, namely D2D relay, is studied in the second place. Small cell users can act as relays for users beyond the coverage of small cells and help them access to the small cell APs so as to improve the experience of these users especially when they are far away from BS but close to small cell APs. We consider the power optimization with user QoS constraint, and design a joint D2D relay selection, power control, access mode selection and resource allocation strategy.