180 research outputs found
A Novel Network NOMA Scheme for Downlink Coordinated Three-Point Systems
In this paper, we propose a network non-orthogonal multiple access (N-NOMA)
technique for the downlink coordinated multipoint (CoMP) communication scenario
of a cellular network, with randomly deployed users. In the considered N-NOMA
scheme, superposition coding (SC) is employed to serve cell-edge users as well
as users close to base stations (BSs) simultaneously, and distributed analog
beamforming by the BSs to meet the cell-edge user's quality of service (QoS)
requirements. The combination of SC and distributed analog beamforming
significantly complicates the expressions for the
signal-to-interference-plus-noise ratio (SINR) at the reveiver, which makes the
performance analysis particularly challenging. However, by using rational
approximations, insightful analytical results are obtained in order to
characterize the outage performance of the considered N-NOMA scheme. Computer
simulation results are provided to show the superior performance of the
proposed scheme as well as to demonstrate the accuracy of the analytical
results
Investigation on Evolving Single-Carrier NOMA into Multi-Carrier NOMA in 5G
© 2013 IEEE. Non-orthogonal multiple access (NOMA) is one promising technology, which provides high system capacity, low latency, and massive connectivity, to address several challenges in the fifth-generation wireless systems. In this paper, we first reveal that the NOMA techniques have evolved from single-carrier NOMA (SC-NOMA) into multi-carrier NOMA (MC-NOMA). Then, we comprehensively investigated on the basic principles, enabling schemes and evaluations of the two most promising MC-NOMA techniques, namely sparse code multiple access (SCMA) and pattern division multiple access (PDMA). Meanwhile, we consider that the research challenges of SCMA and PDMA might be addressed with the stimulation of the advanced and matured progress in SC-NOMA. Finally, yet importantly, we investigate the emerging applications, and point out the future research trends of the MC-NOMA techniques, which could be straightforwardly inspired by the various deployments of SC-NOMA
Exploiting Full/Half-Duplex User Relaying in NOMA Systems
In this paper, a novel cooperative non-orthogonal multiple access (NOMA)
system is proposed, where one near user is employed as decode-and-forward (DF)
relaying switching between full-duplex (FD) and half-duplex (HD) mode to help a
far user. Two representative cooperative relaying scenarios are investigated
insightfully. The \emph{first scenario} is that no direct link exists between
the base station (BS) and far user. The \emph{second scenario} is that the
direct link exists between the BS and far user. To characterize the performance
of potential gains brought by FD NOMA in two considered scenarios, three
performance metrics outage probability, ergodic rate and energy efficiency are
discussed. More particularly, we derive new closed-form expressions for both
exact and asymptotic outage probabilities as well as delay-limited throughput
for two NOMA users. Based on the derived results, the diversity orders achieved
by users are obtained. We confirm that the use of direct link overcomes zero
diversity order of far NOMA user inherent to FD relaying. Additionally, we
derive new closed-form expressions for asymptotic ergodic rates. Based on
these, the high signal-to-noise radio (SNR) slopes of two users for FD NOMA are
obtained. Simulation results demonstrate that: 1) FD NOMA is superior to HD
NOMA in terms of outage probability and ergodic sum rate in the low SNR region;
and 2) In delay-limited transmission mode, FD NOMA has higher energy efficiency
than HD NOMA in the low SNR region; However, in delay-tolerant transmission
mode, the system energy efficiency of HD NOMA exceeds FD NOMA in the high SNR
region.Comment: 15 pages,10 figure
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