Mode selection map in device-to-device communication

Abstract

One of the recent features presented by the Long Term Evolution - Advanced (LTE-A) standard is enabling the network User Equipments (UEs) to directly communicate with each other without routing the signal through evolved-Node B (eNB). This is called the Device-to-Device (D2D) transmission and it brings different types of gains to the network. The UEs are enabled to choose their transmission mode among the reuse, dedicated, and cellular modes. For a network consisting of a pair of D2D enabled UEs, a cellular UE, and an eNB, the mode selection procedure indicates the best mode to be chosen by the D2D pair while the cellular UE is in communication with the eNB. The reuse and dedicated modes are direct transmission while the cellular mode is the traditional cellular transmission. In the reuse mode the same frequency resources are used by the D2D pair and the cellular user. However, in the dedicated and cellular modes, different resources are allocated for the D2D and cellular transmission. In this work, we show that there are certain regions in the network that if the moving UE stays in them, a specific transmission mode is always selected for the transmission between D2D pair. The set of these regions is called the mode selection map of the network. We use our mode selection map models to propose a handover mechanism when the moving UE leaves a specific region in the map and enters to a neighboring region. For mode selection map derivation, we present an analytical framework for a simple D2D enabled network for two different channel conditions: 1) Line-of-Sight (LoS) path-loss channel; 2) fading channel. The overall throughput of the network for the reuse, dedicated, and cellular modes is calculated and presented in three different equations. When the channel’s model is LoS path-loss, to find the mode selection map, these equations are equalized two by two and the resulted equation is solved. For the fading channel scenario, due to the probabilistic variation of the channels the expectation of the overall throughput of the network is calculated for three Transmission Modes (TMs) and the resulted functions are equalized two by two and solved. In our study of handover issues in D2D enabled network we propose an algorithm for the case when the cellular UE moves in the network while the communication channels are fixed. The algorithm relies on two decision parameters, i.e. distance from the boundaries of the map and intersection with the boundaries of the map, which are analytically computed. To evaluate the performance of the handover mechanism we develop an analytical approach to calculate two performance metrics, denoted as handover rate and sojourn time, using the mode selection map.

Date	9 May 2017
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Zbigniew Dziong (Supervisor) & Kazem Sohraby (Co-supervisor)