Half-Duplex Relaying in Downlink Cellular Systems

We compare the performance of half-duplex relays in downlink cellular system against a baseline system without relays. We simulate the performance of (i) a collaborative power addition scheme, where the relay boosts the received power (P-CPA) at the mobile locations, and (ii) a CPA scheme with power control (PC-CPA) at the base station and relays. Evaluations are done in the context of a 19-cell, 57-sector set-up in which each of the served users must be delivered a message. The user messages are taken to have the same size and 90% of users in the network must be served. Improvements over the baseline due to relay deployments are measured in terms of increase in common rate of users as well as power savings in terms of reduction in peak or average power transmitted by base stations. In the CPA schemes with base stations and relays transmitting at full power, the peak power saving is 1.46 dB, alternately, the throughput improvement over a 1 bit/sec/Hz baseline rate is 21%. In the PC-CPA scheme, the peak power saving is 2.6 dB and the average total power in the system can be reduced by 3 dB.