Power Optimization In MIMO-OFDM Systems With Mixed Orthogonal Frequency Division And Space Division Multiple Access Scheme And DTX

With the rapid development of mobile communication business and the increasing number of mobile terminals, there is a need for higher data transmission speed. LTE with MIMO and OFDM as the key technologies well solves the problem of high speed transmission, but it calls the increasing energy consumption at the same time. According to relevant information, the energy consumption of information and communication industry causes about 2% of worldwide CO2 emissions yearly and burdens the electrical bills of network operator.Based on this reason, many algorithms which research on the optimization of power consumption of the base station in MIMO-OFDM system appear in recent years. However, most of these algorithms focus on the allocation of subcarrier, power and transmission rate in a single time slot. And the power consumption of the base station is only represented by the transmit power of the base station in these algorithms. Furthermore, the discontinuous transmission(DTX) technology as an effective power optimization tool, is not well applied to the power optimization of the base station.In this paper, he proposes a new radio resource allocation algorithm to minimize the power consumption of the base station for the MIMO-OFDM systems with different QoS constraints of users, in which the power consumption of the base station is represented by the transmit power and the power loss caused by other components of the base station. DTX technique is applied in the systems with mixed OFDMA and SDMA which makes the dimension of resource allocation increasing from frequency to frequency, time and space. Depending on the method of power allocation, the proposed algorithm can be divided into two different algorithms:(a)The resource allocation algorithm on the premise that power is allocated by the waterfilling method,(b)The resource allocation algorithm on the premise that subcarriers occupied by one user are required to have the same signal-to-noise-ratio(SNR). To reduce the complexity of the algorithm, both the two algorithms in this paper are divided into two steps. In the first step, the active time in the DTX mode of one OFDM frame is estimated under the assumption that every user experiences slow time-varying fading in an OFDM frame. In the second step, subcarriers, power and transmission rate are allocated in the active time slots. Although the proposed algorithm is suboptimal due to high computation complexity, simulation results show that the proposed algorithm can reduce the power consumption of the base station and improve resource utilization.