The fifth-Generation mobile network introduces a new technology called Device-to-device (D2D) Communication which allows User Equipment (UE) to communicate directly with each other, without the need for Base Station or Evolved Node–B (eNB). Thus the mobile data traffic over the eNB can be reduced and throughput can be increased. The objective of this paper is to provide relaying service in cellular network, which has the capability of expanding the network coverage and reducing the traffic over cellular network by using D2D communication. It is achieved by using a technology called Proximity Service (ProSe), in which ProSe Direct Communication and ProSe Direct Discovery enable to identify the UE which are out of network coverage. Then the relay node is selected for serving the UE which are out of network coverage on the basis of Channel Quality Indicator (CQI) and the signal strength between the UE that are in coverage and the UE that are out of network coverage. The UE whose CQI value is high are selected based on certain criteria and are allowed to act as relays. The experiments show that the proposed technique with 5 UE_Relay maintains the D2D communication for longer period than the traditional techniques. Thus, the UE that are out of network coverage are served for more duration by extending the network coverage of the eNB and by relaying data using D2D offloading.

第五代移动网络引入了一种称为设备到设备 (D2D) 通信的新技术，该技术允许用户设备 (UE) 直接相互通信，而无需基站或演进型节点 B (eNB)。因此，可以减少 eNB 上的移动数据流量并增加吞吐量。本文的目标是在蜂窝网络中提供中继服务，具有通过使用D2D通信扩大网络覆盖范围和减少蜂窝网络流量的能力。它是通过使用称为接近服务 (ProSe) 的技术实现的，其中 ProSe 直接通信和 ProSe 直接发现能够识别处于网络覆盖范围之外的 UE。然后根据信道质量指示符(CQI)和覆盖范围内的UE与网络覆盖范围外的UE之间的信号强度，选择中继节点为网络覆盖范围外的UE提供服务。CQI值高的UE是根据一定的标准选择出来的，允许作为中继。实验表明，所提出的技术具有 5ü Ë _{ř Ë升一ý}保持用于比传统技术更长时间的D2D通信。因此，通过扩展 eNB 的网络覆盖范围和通过使用 D2D 卸载中继数据，在网络覆盖范围外的 UE 得到服务的持续时间更长。