Genadi Velev

Energy-Efficient D2D Discovery for Proximity Services in 3GPP LTE-Advanced Networks: ProSe Discovery Mechanisms

Device-to-device (D2D) communications facilitate promising solutions for service optimization and spectrum/capacity efficiency in the Third-Generation Partnership Project (3GPP) networks. A key enabler for D2D communications and proximity services (ProSe) is the device discovery process. Currently, many aggressive peer discovery methods discussed in 3GPP could induce high energy consumption. Therefore, a critical objective in efficient D2D proximity service deployments is how to prolong the battery life time of user equipments (UEs) by managing discovery cycles intelligently. In this article, D2D discovery mechanisms discussed in the 3GPP are studied in terms of energy consumption aspects. In particular, we consider an efficient D2D discovery mechanism that takes advantage of the concept of proximity area (P-Area), a dynamic geographical region wherein UEs activate their D2D capabilities. The mechanism enables UEs to perform D2D discovery procedures only when there is a high probability to find other UEs subscribed to the same service. The energy consumption profiles of various discovery mechanisms are evaluated using simulations, and the results indicate that significant energy savings can be obtained using the considered discovery mechanism.

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.