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Go to Editorial ManagerThe continuous growing developments in the traffic of mobile data limits the data throughput and capacity of cellular networks. “Heterogeneous Networks (HetNets)” are efficient solution to realize such demands. However, in HetNets, the congestion on the overloaded cellular network can be increased when the traffic of data is pushed from a cellular network to the Wi-Fi. In practice, offloading the cellular data traffic to a Wireless Local Area Network (WLAN) depending on the signal quality is a broadly deployed method to solve such problem. The use of Device to Device (D2D) communication further enhances the traffic offloading in WLAN systems and helps to obtain better throughput, end-to-end delay and network load. However, the critical offloading potential and its impacts on the whole performance is not totally understood. In this paper, the offloading of Long Term Evolution (LTE) traffic is presented using a WLAN for voice and video applications. A comparison is performed among two WLAN mecha- nisms; Distributed coordination function (DCF) and Point Coordination Function (PCF). As well, the effect of add- ing a D2D technology to the PCF is discussed. The WLAN effectively offloaded nodes at their Signal to Interference and Noise Ratio (SINR) becomes more than a specific threshold. Results presented that the PCF mechanism outper- forms the DCF one in terms of packet loss ratio, throughput and the maximum load of the entire network. In addi- tion, the use of a D2D serviced in the PCF helps in further reduction in the network load.
With the appearance of Fifth Generation (5G) technology , its necessary to fast the enhancing of the current networks, because of the limitations of Fourth Generation (4G) in terms of data transmission. Although the benefits of the Orthogonal Frequency Division Multiplexing (OFDM) standard of the LTE systems, it has demerits such as rises the Peak-to-Average Power Ratio (PAPR) as well, high Out-Of-Band Emission (OOBE). Thus, it is considered unsuitable for 5G. In this paper, the filtered OFDM (f-OFDM) is proposed for 5G wireless communication systems as an alternative of OFDM because of its low OOBE. Nevertheless, a trade-off between minimize Bit Error Rate (BER) and OOBE and managing PAPR values are the challenge. One of the most important objectives in this paper is achieving balance among this trade-off through proposing concatenated Reed-Solomon (RS)-Hamming codes to improve f-OFDM systems performance. The proposed method utilizes an external RS (7, 1) code with an internal Hamming (7, 4) codes, then appended of an interleaver to combat random errors and help RS code in correcting errors. The results indicated that the proposed f-OFDM system significantly reduced OOBE values compared to familiar OFDM system owing to use FIR digital filter, while minimizes PAPR and improved BER performance due to combined with concatenated codes. Thereby, the suggested system is presented as a highly competitor candidate future wireless communication systems thank to these benefits.