Novel Frameworks for Prioritizing Resource Allocation in Application-Based D2D Communication in 5G Cellular Network

Abstract

Device-to-Device (D2D) communication is one of the supporting pillars of 5G technology and is recognized as a potential solution for supporting all the expectations of 5G users. D2D communication enables mobile devices in close proximity to communicate directly, bypassing the need for a base station as in traditional cellular networks. D2D communication can be utilized for both public safety (PS) and commercial applications (CA). It can either reuse the resource blocks assigned to the cellular user (underlay) and enhance the spectrum utilization or use a dedicated amount of spectrum (overlay) mainly reserved for D2D communication. The primary focus of this research is to design an efficient framework for resource allocation according to the different applications and optimize power for D2D-enabled cellular communication that prioritizes PS applications ahead of CA applications during the resource allocation. Furthermore, we also consider enhancing the sum rate of the system by sharing the resources and preserving the Quality of Services (QoS) for all users in the network. First, we examine inband-overlay D2D communication to prioritize PS applications over CA applications and propose modified versions of the Round-Robin(RR) algorithm, namely the Weighted Round-Robin (WRR) algorithm for resource allocations under a oneto- one scheme. The standard RR algorithm considers all D2D pairs equally, irrespective of application types. However, in the WRR approach, a scaling factor known as "weight" is employed to prioritize the count of PS D2D pairs before considering the CA D2D pairs. The second work in the thesis involves one-to-one inband underlay D2D communications which focus on providing an upper hand to PS users over CA users. It proposes two iterative algorithms for resource allocation and sharing, and power optimization. Iterative resource allocation considers maximum channel gain for assigning resources to cellular users, and the iterative resource sharing algorithm uses the first or second highest cellular and D2D user throughput combination to give PS an edge over CA users. The iterative power optimization algorithm searches for the optimum power required for the guaranteed transmission of a D2D transmitter. The power value for transmission is optimized by the iterative power algorithm, which continuously decrements the value from the initial maximum power limit set. The third study of the thesis explores the possibility of sharing the resources by PS D2D pairs rather than CA D2D pairs in one-to-many inband underlay D2D-enabled cellular networks. We have developed two frameworks namely Channel State Information-based Resource Allocation (CSIRA) for resource allocation and Binary Search Power Control Mechanism (BSPCM) for power optimization in these scenarios. The CSIRA framework forms PS and CA D2D pairs clusters by utilizing the K-means clustering algorithm and authorizing more PS users to share the resources. The BSPCM framework uses a binary search method to search for the optimum transmit power for the D2D transmitter in the power limit. In the fourth study of the thesis, we analyze the challenges and potential solutions for resource sharing in a many-to-many strategy for inband underlay D2D communications and propose two frameworks to increase more active PS applications when compared to CA applications in the system. Cluster-based Many-to-Many Resource Allocation and Resource Sharing (CMMRARS) and Constant Time Power Control Algorithm (CTPCA) are two proposed frameworks where the CMMRARS is utilized to allocate resources to cellular users and sharing of allotted resources by D2D pairs. In contrast, the other framework, CTPCA is responsible for finding the optimal power required for guaranteed transmission for both cellular users and D2D transmitters. The K-means clustering algorithm forms PS and CA D2D pairs clusters, whereas each cluster comprises a set of D2D users as well as cellular users. The simulation results of all the proposed frameworks show a considerable increase in the sum rate of the system and an enhanced spectrum utilization by non-orthogonal assignment of resources to D2D users in the cellular networks. In addition, there is an increase in the active number of PS applications when compared with CA applications in the system, and it preserves the minimum QoS required for all the users in the network.