The Enhanced Multicast Technology In Cellular And D2D Hybrid Network

As the large screen multifunctional smart terminals are popular and broadband multimedia business is booming, they bring unprecedented challenges to the already scarce spectrum resources. The key issue in the next generation wireless networks is how to utilize the limited spectrum resource efficiently. Nowadays, the MBMS (Multimedia Broadcast Multicast Technology) can greatly improve the spectrum utilization. Device-to-Device (D2D) multicast technique is a kind of new communication technology that combines the traditional multicast technology with D2D technology. It is mainly used for meeting the needs of sharing local data as well as solving the problems of the leakage and misinformation for the cell edge users. Combination of D2D communication and MBMS technology not only enhances and complements network performance, but also alleviate the pressure of the bandwidth and the base station.The main work of this paper is as follows:First, this paper describes the cellular and D2D hybrid network structure, scenarios of D2D multicast communication and key technology of multicast communication, etc. What’s more, it analyzes the wireless resources sharing mode for D2D multicast communication coexists with cellular network and the interference with cellular networks. In addition, it proposes a carrier resources reusing method using features of LTE-advanced, which can effectively avoid the interference between cellular and D2D communication.Second, it proposes a clustering strategy considering the users who store multimedia data serve as cluster head (CH) and distribute data to the users around them in D2D multicast mode. It also stablishes a clustering selection model for the hybrid network. Then it proposes a practical clustering strategy with theoretical analysis through game theory. This algorithm lowers the average transmission time, improves spectrum efficiency and reduces latency.Third, it puts forward a resource allocation scheme with consideration of QoS protection for CeUEs and fairness for D2D multicast groups in hybrid systems. The resource allocation scheme consists of subcarrier assignment algorithm and power allocation algorithm that could be realized by convex optimization, aiming to reduce the computational complexity. The proposed algorithm not only achieves much higher sum-throughput than traditional multicast method but also maintains better fairness for different D2D multicast groups.