128 research outputs found
Short-Packet Downlink Transmission with Non-Orthogonal Multiple Access
This work introduces downlink non-orthogonal multiple access (NOMA) into
short-packet communications. NOMA has great potential to improve fairness and
spectral efficiency with respect to orthogonal multiple access (OMA) for
low-latency downlink transmission, thus making it attractive for the emerging
Internet of Things. We consider a two-user downlink NOMA system with finite
blocklength constraints, in which the transmission rates and power allocation
are optimized. To this end, we investigate the trade-off among the transmission
rate, decoding error probability, and the transmission latency measured in
blocklength. Then, a one-dimensional search algorithm is proposed to resolve
the challenges mainly due to the achievable rate affected by the finite
blocklength and the unguaranteed successive interference cancellation. We also
analyze the performance of OMA as a benchmark to fully demonstrate the benefit
of NOMA. Our simulation results show that NOMA significantly outperforms OMA in
terms of achieving a higher effective throughput subject to the same finite
blocklength constraint, or incurring a lower latency to achieve the same
effective throughput target. Interestingly, we further find that with the
finite blocklength, the advantage of NOMA relative to OMA is more prominent
when the effective throughput targets at the two users become more comparable.Comment: 15 pages, 9 figures. This is a longer version of a paper to appear in
IEEE Transactions on Wireless Communications. Citation Information: X. Sun,
S. Yan, N. Yang, Z. Ding, C. Shen, and Z. Zhong, "Short-Packet Downlink
Transmission with Non-Orthogonal Multiple Access," IEEE Trans. Wireless
Commun., accepted to appear [Online]
https://ieeexplore.ieee.org/document/8345745
Max-Min Fairness Based on Cooperative-NOMA Clustering for Ultra-Reliable and Low-Latency Communications
In this paper, the performance of a cooperative relaying technique in a
non-orthogonal multiple access (NOMA) system, briefly named cooperative NOMA
(C-NOMA), is considered in short packet communications with finite blocklength
(FBL) codes. We examine the performance of a decode-and-forward (DF) relaying
along with selection combining (SC) and maximum ratio combining (MRC)
strategies at the receiver. Our goal is user clustering based on C-NOMA to
maximize fair throughput in a DL-NOMA scenario. In each cluster, the user with
a stronger channel (strong user) acts as a relay for the other one (weak user),
and optimal power and blocklength are allocated to achieve max-min throughput.Comment: 11 pages, 6 figures, This paper has been submitted for IEEE systems
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Short-Packet Communications for MIMO NOMA Systems over Nakagami-m Fading: BLER and Minimum Blocklength Analysis
Recently, ultra-reliable and low-latency communications (URLLC) using
short-packets has been proposed to fulfill the stringent requirements regarding
reliability and latency of emerging applications in 5G and beyond networks. In
addition, multiple-input multiple-output non-orthogonal multiple access (MIMO
NOMA) is a potential candidate to improve the spectral efficiency, reliability,
latency, and connectivity of wireless systems. In this paper, we investigate
short-packet communications (SPC) in a multiuser downlink MIMO NOMA system over
Nakagami-m fading, and propose two antenna-user selection methods considering
two clusters of users having different priority levels. In contrast to the
widely-used long data-packet assumption, the SPC analysis requires the redesign
of the communication protocols and novel performance metrics. Given this
context, we analyze the SPC performance of MIMO NOMA systems using the average
block error rate (BLER) and minimum blocklength, instead of the conventional
metrics such as ergodic capacity and outage capacity. More specifically, to
characterize the system performance regarding SPC, asymptotic (in the high
signal-to-noise ratio regime) and approximate closed-form expressions of the
average BLER at the users are derived. Based on the asymptotic behavior of the
average BLER, an analysis of the diversity order, minimum blocklength, and
optimal power allocation is carried out. The achieved results show that MIMO
NOMA can serve multiple users simultaneously using a smaller blocklength
compared with MIMO OMA, thus demonstrating the benefits of MIMO NOMA for SPC in
minimizing the transmission latency. Furthermore, our results indicate that the
proposed methods not only improve the BLER performance but also guarantee full
diversity gains for the respective users.Comment: 12 pages, 8 figures. This paper has been submitted to an IEEE journal
for possible publicatio
Resource Allocation for UAV-Assisted Industrial IoT User with Finite Blocklength
We consider a relay system empowered by an unmanned aerial vehicle (UAV) that
facilitates downlink information delivery while adhering to finite blocklength
requirements. The setup involves a remote controller transmitting information
to both a UAV and an industrial Internet of Things (IIoT) or remote device,
employing the non-orthogonal multiple access (NOMA) technique in the first
phase. Subsequently, the UAV decodes and forwards this information to the
remote device in the second phase. Our primary objective is to minimize the
decoding error probability (DEP) at the remote device, which is influenced by
the DEP at the UAV. To achieve this goal, we optimize the blocklength,
transmission power, and location of the UAV. However, the underlying problem is
highly non-convex and generally intractable to be solved directly. To overcome
this challenge, we adopt an alternative optimization (AO) approach and
decompose the original problem into three sub-problems. This approach leads to
a sub-optimal solution, which effectively mitigates the non-convexity issue. In
our simulations, we compare the performance of our proposed algorithm with
baseline schemes. The results reveal that the proposed framework outperforms
the baseline schemes, demonstrating its superiority in achieving lower DEP at
the remote device. Furthermore, the simulation results illustrate the rapid
convergence of our proposed algorithm, indicating its efficiency and
effectiveness in solving the optimization problem.Comment: This paper is accepted by IEEE VTC 2023-Fall, Hong Kong, Chin
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