A Low-Complexity Scheduling for Joint Unicast and Multicast Transmissions in LTE-A Network

LTE broadcast is an emerging 4G technology that allows the transmission of the same content, typically MBMS streams, to multiple users located in one or many cells belonging to a common area called Multicast Broadcast Single-Frequency Network (MBSFN) area. This promising transmission technique allows significant bandwidth saving but faces many challenges in the joint management of unicast and multicast/broadcast transmissions, especially with the evolved MBMS (eMBMS) that allows unicast reception in the MBSFN subframes. In a recent work, an algorithm based on finding the best multicast users' grouping with respect to their channel conditions, and making resource allocations for unicast users and multicast subgroups according to a predefined fairness function has efficiently solved the problem. However, the allocation for both unicast and multicast connections was made in terms of resource blocks (RB), which does not comply with 3GPP standards. In this paper, we propose a compliant standard version of this algorithm, which considers subframes as a scheduling granularity. Our proposition significantly reduces the computation complexity from O(M
⁴
) to O(M) and overcomes the drawbacks of the initial algorithm, which is clearly shown in the numerical results of our enhanced version, especially in terms of time complexity and total data rate received by all users, while keeping a comparable performance in terms of system utility.