Abstract
Network coding (NC) can greatly improve a system’s performance on throughput and channel utilization via corresponding signal processing on the relay side. Implementation of NC in relay-assisted device-to-device (RA-D2D) communications is a promising way to further explore the advantages of RA-D2D communications in cellular systems. This paper proposes a signal processing scheme for RA-D2D which jointly takes into account NC and optimal relay selection. First, the optimal relay user equipment (UE) is selected by jointly considering the end-to-end data rate, end-to-end transmission delay, and relay survival time. Then, in the procedure of signal processing, the transmitted useful signal is combined with interference signal for NC operation, and finally, the original useful signal is recovered at the destination node. Simulation results show that the proposed scheme is able to not only eliminate the interference effectively but also has a superior performance on end-to-end transmission delay, reachability, and amount of transmitted information than that without NC. In particular, signal processing via NC is equivalent to encrypting the signal, which further enhances the information security in D2D communications.
Highlights
People constantly send and receive messages in different ways, in which the essence is to solve the problems on signal transmission, processing, and detection [1, 2]
In [18], the relay-assisted D2D (RA-D2D) signal processing based on Network coding (NC) was further improved, in which the coding and modulation were adaptively performed according to link quality
In [20], NC was implemented into multi-hop and multi-antenna RA-D2D signal processing, and it was proved that bringing NC into RA-D2D signal processing could achieve further improvement on the system performance and enhance security in the data transmission
Summary
People constantly send and receive messages in different ways, in which the essence is to solve the problems on signal transmission, processing, and detection [1, 2]. The main contributions of this paper are summarized as follows: First, we propose a session mechanism for network coding involved D2D communications, which is mainly implemented in the relay-assisted D2D communication mode With this mechanism, the interference signal generated by the cellular users is used to perform network coding process at the relay node, thereby improving transmission efficiency and saving resources while eliminating interference. Based on a comprehensive survey on the path loss scenarios mentioned in 3GPP releases (e.g., Release 9 [24]), a channel gain model given in [25] is adopted in analysis of the communication process, which jointly considered the path loss, slow fading, and fast fading. Where K0da−,bα is the path loss given in 3GPP Release 9, K0 is a constant whose value corresponds to the implemented path loss model, da,b is the distance from the transmitter to the receiver, α is is the path loss exponent, βas,b is slow fading obeying the logarithmic distribution, and βaf ,b is fast fading obeying the exponential distribution [26]
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