Interference Cancellation Techniques For Device-To-Device Discovery In Out-Of-Coverage Networks

Nowadays, the number of users and connected devices linked to a cellular network is very large. For that reason, new technologies that do not need network support, such as Device-to-Device (D2D) communication, have been developed. D2D communications may occur randomly, uncoordinated and unscheduled, giving rise to interference, which critically impairs the ability of a device to identify its neighbors - a process known as D2D discovery. This work proposes an innovative method to mitigate the interference problem in the D2D discovery process; it is based on a new approach to enhance the detection of multiple concurrent transmitting devices, namely by considering the use of multiple orthogonal pilot sequences jointly with a new receiver block, and on a new procedure that extends the Successive Interference Cancellation (SIC) technique using a single time slot (intra-SIC) to a SIC process that is able to consider several time slots (inter-SIC), which is made possible due to the creation of a new frame concept - the virtual frame. A simulation framework is implemented with the purpose of demonstrating how the proposed method would work and confirm its suitability and effectiveness. It is shown that, for a high number of contending devices and without the use of any type of SIC, about 50% of the discovery sessions are successfully completed; by applying intra-SIC, the discovery success ratio increases to 75%-80%; however, by considering the method proposed herein, 85%-95% of the discovery sessions are successfully completed.