Research On Device-To-Device Communication For Data Delivery

With the development of information technology and wireless network technology, wireless multimedia services has shown explosive growth trends. Under the current network structure, how to use the existing resources effectively to achieve a high data rate delivery has become one of the most important research areas in the wireless network. To meet the increasing demands of new business service, Device-to-Device (D2D) communication, as an effective transmission scheme, is seen as the one of the most promising areas of large-scale data delivery technology faced by mobile cellular networks. The core idea of D2D communication is the effective data delivery by using the advantage of D2D communication, such as high data rate, high spectral efficiency, and low power consumption, rather than through the base station. A number of famous universities, research agencies and companies have put much attention on the research of D2D communication, and finish some important research works.It can be proved from the theoretical aspects that D2D communication can significantly improve system performance, such as network throughput improvement, spectral efficiency enhanced, network offload, etc. However, when the D2D is introduced into conventional cellular network, the context of network is complex and volatile. Therefore, it is better to find out an optimal D2D communication scheme in which to meet the QoS requirement of user, reduce the interference between each other. It is instructive and meaningful to further enhance the performance of data delivery in D2D assisted cellular networks.In this paper, we study a resource allocation scheme to improve the reliability of D2D communication when a large number of D2D users coexistence in the limited area, firstly. Second, we study the resource allocation to improve the capacity of the D2D assisted cellular networks under the constrain of the user’s QoS requirements and revenue. There are two scenarios including orthogonal frequency partitioning and universal frequency reuse strategy. Finally, we study an effective data delivery scheme of D2D assisted multicast communication. The main contribution of this paper include the following aspects.In the case of a large number of D2D pairs coexistence, we model the D2D networks with random geometry theory. The number of D2D pairs are modeled as a Poisson distribution on time dimension and the location of D2D pairs follow uniformly distribution. We derive the success probability of D2D communication by using a complex channel and analysis the key factor of success probability. Then, we propose a reliability improvement scheme using clustering and power control when a large number of D2D users coexistence in the limited area. Simulations results are conducted to confirm our analytical results.In the case of orthogonal frequency partitioning, we study a resource allocation scheme under the constrain of QoS support. The proposed approach is optimal in terms of throughput, and is subjected to a sensible QoS requirement, which guarantees that macrocell and D2D achieve a prescribed data rate and outage probability respectively. Our solution consists of two phases. In the first phase, the minimum sub-channels are allocated to the macrocell to satisfy their data rate requirements. In the second phase, the redundant sub-channels are allocated to D2D pairs to maximize the throughput of D2D networks. Extensive simulations demonstrate the superior performance of the proposed solution compared with the existing scheme.In the case of universal frequency reuse strategy, there are a number of cellular users and one D2D pair reuse the same resource. We study a joint power and frequency allocation scheme under the constrain of user’s utility. First, the payoff function and cost function of D2D communication are constructed to ensure the profit of D2D communication. Then, we propose a joint power and frequency allocation scheme under the constrain of user’s utility to maximize the throughput of hybrid network. In the end, two schemes referred to as optimization and sub-optimization algorithms respectively. The optimization algorithm is a dual decomposition method based on the convex theory. The sub-optimal algorithm is a two-step scheme. Simulation results show that the throughput is improved compared with two traditional chimes. In addition, the sub-optimal algorithm reduces the computational complexity greatly and the network capacity close to the global optimum.In order to improve the efficiency of data delivery in the cellular network, we study a data delivery strategy based on D2D multicast communication. There is a two-step strategy. First, we propose a social-aware approach for optimizing D2D communication by exploiting two layers:the social network and wireless layer. In this stage, the neighboring graph is constructed. Second, we proposes a clustering scheme considering the users who store multimedia data serve as cluster head (CH) and distribute data to the users around them in D2D multicast mode. Finally, the user who have not found any useful packets within a specified time interval trys to connect to the BS. This algorithm improve the throughput of network and the traffic of eNB has been released.