Energy Efficiency In Orthogonal And Non-Orthogonal Communication System

With the increasing of mobile applications and mobile devices, amount of energy is consumed by wireless communication, so energy efficient (EE) wireless communication have aroused much research interest in academia and industry. Improving the energy efficiency of network and termi-nal can effectively reduce the energy consumption of wireless communication and reduce carbon emissions to the environment. This paper mainly study the energy efficiency of orthogonal sharing and non-orthogonal sharing channel in resource allocation problems.Most of the research work is focused on improving the rate and the capacity of the network at present, however green communication technology will be one of the key communication technolo-gy in the future with the development of wireless communication. Since a large amount of energy is consumed by data transmission, we can design the green communication technology by research-ing the energy efficiency problems of wireless communication. On the other hand, orthogonal frequency division multiple access (OFDMA) has been widely applied in wireless communication systems due to its high efficiency and robustness against broadband channel fading. Therefore, lots of work has been done to improve the energy efficiency of users in the OFDMA system. Rather than some research work studying the overall system energy efficiency, our research work is fo-cused on the energy efficiency for each individual user. Our objective is to maximize the energy efficient for each individual user with considering the fairness, and we also study the balance of the energy efficiency between the users to provide operators with more flexible resource alloca-tion methods. For example, we can put different emphases to different users, such as allocating more resource to those users with low battery capacities to improve the energy efficient and extend the battery lifetime. In order to optimize the energy efficiency of each user, a multiple-objective optimization problem (MOOP) is formulated. To find its solution, we first convert it into two different single-objective optimization problems using the weighted-sum approach and the max-min approach, respectively. The single-objective optimization problems are non-convex due to the combinatorial channel allocation variables. Therefore, for both problems, we first provide an upper bound algorithm by relaxing the combinatorial variables and then develop a suboptimal heuristic algorithm. The sum-of-ratios optimization and the generalized fractional programming (GFP) are utilized for the weighted-sum problem and the max-min problem, respectively. By changing the weight in the weighted-sum method can control resource allocation of each user and by using max-min method can effectively ensure the fairness of each user.Interference will be one of the major obstacles to improve the performance in the future wire-less communication systems, and therefore it is necessary to study energy efficiency of interference network. some scenarios of non-orthogonal network can allow some users to share the some re-sources to improve the utilization of resources, however it will cause interference between users. In this paper, we proposes a multi-objective optimization problem to maximize the energy effi-ciency of each user, and ensure the smallest transmission rate of each user. With considering the energy efficiency of the user or the system, it will be difficult to deal with the resource allocation problems in interference network. In this paper, we use the weighted Tchebycheff to transform the multi-objective optimization problem into a single objective problem, and use the Dinkelbach method to deal with the fraction structure in energy efficiency problem, and use the concave-convex procedure (CCCP) method to deal with the nonconvex problem. Based on the above, a power con-trol algorithm is developed for the interference network to achieve at least a local optimum. The proposed algorithm is compared with the orthogonal bandwidth sharing, where each user orthogo-nally shares the whole bandwidth without interfering each other. The performance of the proposed algorithms is verified by numerical results, which show that it is better to share the bandwidth or-thogonally rather than non-orthogonally if the interference between each user pair is stronger than a given threshold.