Cooperative Network-Coded Multicast for Layered Content Delivery in D2D-Enhanced HetNets

The rapid growth in multimedia applications over cellular networks calls for multicast services. Multicast is an efficient means of delivering contents to multiple users while efficiently utilizing network resources. Layered streaming, e.g., scalable video coding (SVC) provides an excellent solution to handle channel diversities in wireless multicast. This paper presents a cooperative multicast scheme for scalable video content delivery in D2D-enabled heterogeneous cellular networks (HetNets). To extend the multicast service beyond base stations (BSs), D2D links are used to help relay content for cellular multicast. Network coding (NC), implemented through random linear network coding (RLNC) with unequal error protection (UEP) is incorporated in layered contents to enhance reliability and throughput. This paper tries to optimize the multicast scheduling procedures, aiming to assign the optimal modulation and coding schemes (MCSs) for transmissions. The constraints on cache size, backhaul capacity and channel fading are comprehensively considered. Besides, this paper also presents a interference-aware approach for D2D link selection in order to further improve the cooperative multicast. Sufficient numerical results have demonstrated the improvement brought by the proposed scheme significantly on the content delivery efficiency as well as quality of experience (QoE).