Energy efficient handover algorithm in OFDMA systems

Traditional handover algorithms are based on received signal strength indicator (RSSI) and traffic load intensity in orthogonal frequency division multiple access (OFDMA) systems, in order to guarantee all UEs´ Quality of Service (QoS) and handover success ratio, a transceiver is activated even if there is only one low date rate activated user in its coverage area. In this paper, we propose an energy efficient handover algorithm combined coordinated multiple-points (CoMP) with OFDMA in a cellular systems, energy efficiency is introduced into the handover algorithm as an important parameter. The idea of the design is to enable adjacent cells to shutdown partial transceivers in some timeslots in low traffic conditions by concentrating the activated edge UEs to less cells. All activated UEs are classified into edge users and center users according to their distance to base stations, the analysis indicates that there exist an optimal edge distance corresponding to the maximum energy efficiency under different load for the proposed algorithm. Furthermore, a practical and low-complexity scheme that only considers the edge users is put forward. The edge users are identified by the reference signal received power (RSRP). Simulation results show that it can obtain up to 60% energy reduction at low traffic scenario.