Relaying in green communication systems

This chapter has discussed energy efficiency issues and comparisons among relay protocols. A widely applicable system model has been introduced along with relevant energy efficiency metrics. In addition, the importance of using models that can compute the overall energy consumption (not just the transmitted radio-frequency power) has been emphasized. We have discussed in detail the energy efficiency optimization of different relay protocols including AF,DF and CF. Mathematical methods including a general fractional programming framework to minimize the energy consumption ratio have been presented and the best energy efficiency regions for deploying relays have also been presented. This chapter has also studied the benefits of using relaying to form VMIMO network configurations. The performance trade-offs for different relay protocols in this scenario have been discussed and compared. The spectral and energy efficiency comparisons of different relay setups with varying numbers of antennas have also been discussed.