Abstract

Device-to-Device (D2D) communication represents a promising enhancement to 4G LTE-Advanced (LTE-A) networks by enabling direct communication between user equipment (UE) without routing data through an evolved Node B (eNB). This paper investigates the Quality of Service (QoS) aspects of D2D communication in LTE-A environments, with a specific focus on two critical performance metrics: delay and throughput. The study evaluates D2D performance under different spatial scenarios using simulation tools such as OMNET++, INET, and SimuLTE. Two scenarios are considered: UEs located in proximity under the same eNB, and UEs distributed across adjacent cells.Simulations reveal that D2D communication significantly reduces delay and enhances throughput when UEs are close to each other, even if they are far from the eNB. In contrast, the traditional Relay Path introduces additional delay due to data processing and transmission through the eNB. The results further show that while D2D outperforms Relay Path in short to medium distances (up to approximately 100 meters), performance degrades at longer ranges due to signal attenuation and interference.The findings confirm that D2D communication, under the right conditions, can improve network performance by offloading traffic from the core network and reducing latency. This paper also identifies the challenges of interference management, resource allocation, and device discovery in D2D scenarios. The research contributes to ongoing efforts in optimizing D2D deployment and meeting the QoS targets specified in 3GPP Release 12 standards. Future work may explore dynamic mode selection and integration with emerging 5G systems.

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Keywords

D2D communication, LTE-A, QoS, OMNET++, throughput, delay