Joint cell selection and subchannel allocation for energy efficiency in small cell networks: A coalitional game

Due to the dramatic growth of mobile data traffics, small cell network concept has been considered as a promising technique for mobile data offloading and enhancing spectrum utilization in the Long Term Evolution (LTE)-Advanced networks. Small cell networks allow the user equipment (UE) to transmit data through small cells instead of using only macro cells by reusing the same radio spectrum of the macro cells. A UE can select to transmit data through either a small cell or a macro cell. Moreover, the network needs to allocate the appropriate subchannel and the transmission power for each UE in the macro cells and small cells in order to avoid the harmful interference. In this paper, we focus on the problem of joint cell selection and resource allocation (i.e., subchannels and transmission power) for energy efficiency in small cell networks. A coalitional game is formulated to select cell and allocate resources where UEs in the same cell are considered to be in the same coalition. Small cell UEs (SUEs) are rational to maximize their individual utilities which equals to minimize the transmission power while transmission rate requirement is satisfied. To select subchannel, a greedy algorithm is used to assign a subchannel for an SUE to approximate an optimal assignment with low complexity. A distributed algorithm is also proposed to find stable coalitions. The simulation results show that the proposed scheme can achieve 31 percent in terms of power saving compared to the static random scheme.