Research And Design Of Energy Efficient Networking In LTE

3GPP Long Term Evolution (LTE) has been considered as the most promising technology in the next generation of wireless communication. While the development of different signal processing technologies have largely improved the physical layer (PHY) performance. Recently, with the deployment of heterogeneous network, LTE wireless networking is also evolving from base station (BS) centralized to user equipment (UE) centralized pattern. Among them, Device-to-Device (D2D) technology has been discussed widely in both LTE standardization and academic research due to its huge potential in increasing system capacity. Besides, with the concentration of all kinds of BSs, the increasing energy consumption of network operation is becoming an important issue. In this thesis, corresponding analyses and optimizations on resource management, interference mitigation and energy efficiency of D2D communication are presented, while the potential impact on energy efficiency of LTE heterogenous network with the application of D2D is also evaluated. The main research contents are shown as following:To begin with, this thesis proposes a Kuhn-Munkres (KM) algorithm based D2D uplink resource allocation to minimize the intra-cell interference. Specifically, we optimize the resource allocation and power control under three different optimization scenarios, which are:fixed power transmission, power controlled transmission and energy efficient transmission. Simulation results and analysis show that the proposed KM based method will achieve30Mbps system throughput gain comparing with the classic greedy algorithm. While from the perspective of optimization on energy efficient transmission, the proposed KM method is able to save7dB transmit power on the terminal side. Moreover, on the cell network side, this thesis obtains the optimal sleeping traffic threshold for small cells which is able to reduce the system energy consumption through cell sleeping. Two parameters are defined to describe and evaluate the sleep strategy, which are Sleep Ration (SR) and Maximum Sleep Cell (MSC). Based on the proposed sleep strategy, the thesis further evaluates the influence on the energy consumption of cell network when D2D communication is applied. Simulation and analysis show that when path loss equals to3.6, the proposed sleep strategy can save30%of the energy on the network side. While with the application of D2D, which is able to facilitate the energy reduction of small cell sleep strategy, up to40%of the energy will be saved. It is shown that D2D communication benefits a lot on the cell network energy saving.In addition, when considering the overall system energy cost, the thesis defines an energy metric function to evaluate the impact on the system energy consumption when D2D is introduced. It is further proved in the thesis that the energy metric function is subject to the quadratic function features. Simulation and results show that even D2D communication is able to save the energy on the cell side, while when considering the overall system situation, the application of D2D may instead cause an extra25.6%energy cost. Hence, an adaptive adjustment of D2D traffic is required to optimize the system energy efficiency.The summary is drawn in the end of this thesis. In addition, several future follow-up plans and potential research areas are also shown.