The use of relays in uplink MU Massive-MIMO system
Carmen Voicu, Madalina Georgiana Berceanu, Simona Viorica Halunga · Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IX · 2018
In an uplink multiuser system in which the users are situated far enough from the base station (BS), or in which the communication is affected by fading, the use of relays can bring a plus in the quality of the information arrived at the BS. In this paper, the performance of an uplink connection for a Massive MU-MIMO system is analysed with or without relay nodes in order to see how the bit error rate metric (BER) improves when the number of antennas at the base station (BS) is increased from 10 to 100 and for different number of active users that simultaneously require mobile resources to accomplish their momentary needs. For a better evaluation of the proposed system we use, two types of relays, one based on amplifyand- forward (AF) protocol and one on decode-and-forward (DF) protocol. At the BS a maximal ratio combiner (MRC) is used to combine the signals received from users and relay, and a minimum mean-square error (MMSE) detection is applied to recover the information sent by each user. The simulations show that, by using relays, we have a significant gain, especially when the number of the active users is close with the number of antennas from the base station.