—Public Safety Networks (PSNs) have been recognized as the key to a successful response to emergency and disaster situations. Recently, the 3GPP-LTE cellular networks open possibilities to enhance public safety services. To position the current LTE to meet the requirements of the evolution of PSNs, this paper proposes an approach to investigates the two key radio technologies, i.e., device-to-device (D2D) communications and user equipment (UE) initiated multicast communications. First, due to physical damage to base stations (BSs) or network congestion, wireless infrastructures may not available to users in post-disaster areas. In such a situation, we propose a D2D communication approach which allows two far apart users to communicate directly without the use of BSs. Then we consider that a UE instead of a BS acts as the multicast transmitter. To satisfy the QoS requirements of emergency group communications, an effective opportunistic multicast scheduling approach is proposed at the MAC layer which can minimize the delay of a multicast. To further improve multicast throughput, D2D relaying technique is also integrated into the proposed multicast scheduling scheme, which can combat the multicast bottleneck when one or very few receivers are with very poor channel conditions.
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