Abstract
In hybrid device-to-device (D2D) and cellular networks, the cross interference between different communication systems severely limits the system performance. Fortunately, non-orthogonal multiple access (NOMA)-based coordinated direct and relay transmission (CDRT) can fully exploit the inherent property of NOMA to minimize such interference, which provides a potential strategy for hybrid networks to enhance the spectral efficiency (SE) and extend the cell coverage. Based on this idea and the superior SE requirements in future wireless networks, a D2D communication assisted uplink CDRT using NOMA is proposed, in which a base station (BS) directly communicates with a cell-center user (CCU) while communicating with a cell-edge user (CEU) with the aid of a relay. Particularly, uplink transmission of CCU and D2D communication from CCU to CEU are jointly designed according to NOMA principle in the cooperative phase. To verify the system performance of the proposed scheme, closed-form expressions of the system ergodic sum rate (SR), outage performance and outage throughput are derived, respectively. Numerical results illustrate that the proposed scheme achieves superior system ergodic SR as well as outage throughput with slight outage performance loss of uplink transmission, compared with conventional NOMA-based uplink CDRT.
Highlights
With the explosive increasing number of advanced smart mobile terminals and diversified development of multimedia applications, the demand for 5G wireless network performance and quality of services (QoS) has risen dramatically [1], [2]
SYSTEM MODEL Consider uplink D2D aided coordinated direct and relay transmission (CDRT) scheme using non-orthogonal multiple access (NOMA) for hybrid cellular and D2D communication network (HCDCN) depicted in Fig.1, where the cell-center user (CCU) directly communicates with the base station (BS) and the cell-edge user (CEU) communicates with the BS via a DF relay while these two users can complete a bidirectional D2D communication process in accordance with the proposed scheme
It is revealed that the proposed DCDRT outperforms the CN-UCDRT in terms of the ergodic sum rate (SR) and outage throughput
Summary
With the explosive increasing number of advanced smart mobile terminals and diversified development of multimedia applications, the demand for 5G wireless network performance and quality of services (QoS) has risen dramatically [1], [2]. Many existing studies focus on the interference management and resource allocation optimization, and pay little attention to the theoretical analysis which is significant for the system performance of HCDCNs. the authors in [28] have derived the system capacity for the proposed D2D assisted downlink CDRT employing NOMA in HCDCNs and verified the proposed scheme can improve the achievable rate. We propose a D2D aided uplink CDRT using NOMA, which can make optimal use of the inherent features of NOMA to improve the system SE and coincidentally reduce the inter-user interference of HCDCNs. only a single cell scenario is considered in this paper, the proposed scheme can be straightforwardly extended to multi-cell scenario by employing OMA among different cells.
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