Abstract
The use of a Software-Defined Network (SDN) approach improves the control and management processes of the complex structured wireless sensor network. Also, it provides higher flexibility and a dynamic network structure. SDN is introduced to efficiently and opportunistically use the limited spectrum to minimize the spectrum scarcity issues. The LEACH protocol is self-organizing and is characterized as an adaptive clustering protocol that randomly distributes energy load among nodes. By using cluster heads and data aggregation, excessive energy consumption is avoided. SDN is often placed in an open environment and is susceptible to various attacks. The routing is based on multihop’s flawless hauling range data transmission between the base station and cluster heads.The advantage of LEACH is that each node has the same probability of being a cluster head, which makes the energy efficiency of each node relatively balanced. Massive multiple-input multiple outputs (MIMO) play a polar role within the fifth generation (5G) wireless networks. However, its performance heavily depends on correct synchronization. Although timing offset (TO) can be avoided by applying orthogonal frequency division multiplexing (OFDM) with an adequate length of cyclic prefix (CP), carrier frequency offset (CFO) is still a challenging issue. Especially in the uplink of multiuser massive MIMO systems, CFO compensation can impose a substantial amount of computational complexity on the base station (BS) due to many BS antennas. However, to the best of our knowledge, no study looks into the joint estimation of CFOs and wireless channels in orthogonal frequency division multiplexing (OFDM) based massive MIMO systems. In this project, we propose a low-complexity CFO compensation technique to resolve this problem. In our paper, to traumatize this issue, we tend to propose a low-complexity frequency synchronization technique with high accuracy for the transmission of multiuser orthogonal-frequencydivision multiplexing-based large MIMO systems. First, we propose a carrier frequency offset (CFO) estimation whose process complexity will increase linearly concerning the quantity of base station (BS) antennas. We then propose a joint CFO compensation technique that is performed when combining the received signals at the BS antennas. As a result, its machine complexity exceeds the number of BS antennas. As a third contribution, the impact of the joint CFO estimation error is studied, and it is tested that by applying our planned joint CFO compensation technique, the joint CFO estimation error causes a continuing section shift solely. We tend to propose an algorithm to expeditiously calculate and take away the estimation error. Our simulation results testify to the effectiveness of our planned synchronization technique. As it is incontestable, our planned synchronization technique results in a bit of error rate performance that is the one for an asynchronous system. This leads to a considerable saving in the computational cost of the receiver. Numerical results are presented to verify the performance of our proposed joint CFO compensation technique and to investigate its computational complexity.