With the ever increasing usage of wireless devices, the power consumption and energy efficiency of cellular networks have become important performance indicators. In recent years, various types of energy saving schemes have been proposed for cellular networks. However, most of these schemes do not take advantage of the advanced features offered by the recent cellular standards, such as the 3GPP release 10 (also known as LTE-Advanced) and beyond. One of the recently proposed energy saving schemes in cellular networks is the cell switch off technique in which a lightly loaded cell is completely switched off and the traffic in that region is absorbed by the nearby cells whose transmit powers are increased to enable larger coverage areas. In this paper, we propose to use the cell switch off scheme without increasing the transmit powers of the active cells; instead, we propose to use the coordinated multipoint (CoMP) transmission radio technology, which is being standardized for the beyond-LTE cellular networks, to enable a sufficient received power level from a number of nearby cells whenever possible. Through simulations with realistic parameters, we demonstrate that the above described cell switch off + CoMP combination used with proper CoMP active set degree yields a more energy efficient solution with better received user experience in comparison to the traditional cell switch off schemes. In the proposed scheme, channel estimations are needed in order to determine the CoMP active set accurately. We analyze the performance by modeling the channel estimation error as a Gaussian random variable with 4, 8, and 12 dB standard deviation and observe that perfect channel estimation can provide up to 46% capacity and 24% energy efficiency increase in comparison to the scenarios with the channel estimation errors.
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