Relaying in downlink cellular systems

We present a simulation study of two relaying schemes in downlink cellular systems. We simulate the performance of two relaying strategies: (i) a collaborative power addition (CPA) scheme, cooperative scheme where the relay collaborates with the base station, and (ii) a simple orthogonal relaying strategy where base stations and relays transmit in orthogonal time slots. 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. All simultaneous transmissions mutually interfere. Improvements due to relay deployments are measured as throughput improvements 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. We observe that the simpler orthogonal relaying scheme performs nearly as well as the more complex collaborative relaying in producing throughput gains and power savings.