Content Delivery through Device to Device Communication

Content caching at mobile user devices (UDs) utilizing device to device (D2D) communication has recently been proposed as an exiting and innovative technology to offload network data traffic and enhance the performance of mobile networks, in terms of latency, throughput, energy consumption, and so on. In this thesis, a novel method of content delivery using multiple devices to single device (MDSD) communication through D2D links is presented. In this method, the Zipf distribution with exponent shape parameter

is adopted to model the content caching popularity for the analysis of the achievable signal to interference plus noise ratio (SINR). In order to investigate the advantage of the proposed MDSD method, firstly, a closed-form expression of the outage probability is theoretically derived for a single D2D communication to evaluate the success of content delivery to the reference UD. Secondly, the expression of the outage probability for MDSD communication is derived, where the outage probability is analysed as a function

of content caching popularity, the density of UDs, and the size of cooperative area. The research work is further extended to address the frequency reuse among different UDs in one cell, where a frequency band factor is introduced, and the optimal radius of the

cooperative area is introduced and analysed. The analytical results, validated by the simulation results, show that the outage probability decreases drastically when the popularity of the content increases, or the radius of the cooperative area increases. Using the given closed-form expression of the outage probability, the area spectral efficiency (ASE) of the system is presented. Furthermore, the results show that as the frequency band factor increases, the outage probability decreases, as well as the ASE decreases. Finally, it is shown that the MDSD outperforms the single D2D-based method.