Enabling group communication for public safety in LTE-Advanced networks

In this paper, we investigate public safety communications based on LTE-Advanced mobile networks. This work has a twofold aim, (i) to secure optimal radio resource efficiency using a mix of synchronous and asynchronous multicast traffic, and (ii) to provide public safety services with minimal interruptions due to mobility in a heterogeneous network environment.To this end, we propose and evaluate three different options for multicast resource allocation: a synchronous scheme, where all multicast cells operate with the same modulation scheme as a single frequency network; an asynchronous scheme, where base stations can decide in a distributed fashion on the multicast configuration; and a coordinated scheme where a central network management entity selects the multicast configuration in a network.For the performance evaluation, different network deployment alternatives and the impact on delay critical group communications using unicast and multicast bearers are analyzed. Different user distributions and mobility scenarios were also considered. We evaluate these schemes using system level simulations with 3GPP LTE-Advanced settings, analyzing the performance in terms of – resource efficiency, energy savings in macro-cellular networks, and optimization of signaling load in heterogeneous networks. From the numerical results, we observe significant gains in terms of resource efficiency as well as power consumption reductions for the multicast scheme over unicast, with minimal impacts due to mobility. The results also indicate that the scheme is flexible enough to handle different types of user distributions and mobility conditions, without compromising the resource utilization efficiency.