Traffic-Aware Relay Sleep Control to Improve Energy Efficiency in Joint   Macro-Relay Networks
  In this letter, we consider a joint macro-relay network with densely deployed relay stations (RSs) and dynamically varied traffic load measured by the number of users. An energy-efficient strategy is proposed by intelligently adjusting the RS working modes (active or sleeping) according to the traffic variation. Explicit expressions related to the network energy efficiency are derived based on stochastic geometry theory. Simulation results demonstrate that the derived analytic results are reasonable and the proposed strategy can significantly improve the network energy efficiency. 
Na Deng, Ming Zhao, Sihai Zhang, and Wuyang Zhou
cs.NI