Improving Network Energy Efficiency through Transmit Antenna Number and Transmission Mode Selection in Multicell Systems

We consider the problem of maximizing network energy efficiency (NEE) in multicell systems, which is defined as the total capacity of all users divided by the total base station (BS) power consumption in the system. We first provide closed-form expressions for NEE when BSs take different combinations of transmission modes and active transmit antenna number. Based on these and assuming all users' statistical channel state information (CSI) is available in all BSs, we provide an algorithm in which the combination with the best network energy efficiency can be selected. Simulations show that, for each combination the calculation results of NEE fit well with the simulation results, and the NEE-optimal combination can be adaptively selected given the users's locations. At last we analyze why the chosen combination is optimal with respect of NEE.