Massive MIMO exploitation to reduce HARQ delay in wireless communication system

As recommended by 5th generation Public-Private Partnership (5G-PPP) and Next Generation Mobile Networks (NGMN), one of the most important 5G requirements is to minimize the delay within the network for delay-sensitive services. Main objective of this work is to exploit massive MIMO technology to reduce Hybrid Automatic Repeat Query (HARQ) retransmission delay. Massive MIMO indoor environment is created by a 3D ray-tracing tool to simulate the received power, phase, delay, and angle of arrival of each ray in the channel. Two sizes of rectangular antenna array are used to evaluate the performance of beamforming in enhancing the bit error rate. This reflects directly on the mean and maximum numbers of packet retransmission. The angle between user-equipments is considered to evaluate the effect of inter-user interference on HARQ. This work opens the door to develop smarter resource allocation algorithms in 5G for delay-sensitive services based on the location and the angle of arrival of the users.