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network-coded multiple access II: Toward Real-Time Operation With Improved Performance

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2015年第2期33卷 264-280页

作者： You, Lizhao Liew, Soung Chang Lu, Lu Chinese Univ Hong Kong Dept Informat Engn Shatin Hong Kong Peoples R China Chinese Univ Hong Kong Inst Network Coding Shatin Hong Kong Peoples R China

This paper presents a first real-time network-coded multiple access (NCMA) system that jointly exploits physical (PHY)-layer network coding (PNC) and multiuser decoding (MUD) to boost the throughput of a wireless local area network (WLAN). NCMA is a new design paradigm for multipacket reception wireless networks, in which the access point can receive and decode several packets simultaneously transmitted by multiple users. Conventionally, multipacket reception is realized using MUD only, whereas the key idea of NCMA is to use PNC together with MUD to realize multipacket reception. Although the feasibility of NCMA has previously been studied by the authors, our previous NCMA prototype was a version with offline signal processing. In addition, our previous investigation left open a number of theoretical and implementation issues, the resolution of which is critical to the adoption of NCMA in real practice. The current investigation makes the following state-of-the-art contributions toward NCMA: 1) we demonstrate a first NCMA system with integrated real-time PHY- and MAC-layer decoding;2) we construct a new unified framework for MAC-layer decoding that yields higher throughput with faster decoding-the faster decoding is one of the key enablers of our real-time implementation;and 3) we design new PHY-layer decoding techniques that overcome the poor performance of the first-generation NCMA prototype at low SNR. Experimental results show that, compared with the previous NCMA prototype, our new NCMA prototype improves real-time throughput by more than 100% at medium-high SNR (>= 8 dB).

关键词： network coding physical-layer network coding multiuser detection multiple access network-coded multiple access implementation

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network-coded multiple access on Unmanned Aerial Vehicle

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2018年第9期36卷 2071-2086页

作者： Pan, Haoyuan Liew, Soung Chang Liang, Jiaxin Shao, Yulin Lu, Lu Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China Chinese Acad Sci Ctr Space Utilizat Key Lab Space Utilizat Technol & Engn Ctr Space Utilizat Beijing 100094 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

This paper presents the first network-coded multiple access (NCMA) downlink system on unmanned aerial vehicle (UAV). The use of UAV as a mobile aerial base station has received much attention in the 5G community in the context of highly mobile and flexible-configurable communication systems. As UAVs are limited by their flight time in the air, achieving high spectral and power efficiency while they are inflight is of great importance. Non-orthogonal multiple access (NOMA) is a promising technique to increase the spectral and power efficiency. Conventional NOMA downlink that makes use of superposition coding in combination with successive interference cancellation (SIC) decoding does not work well in scenarios where the channel conditions of different downlink users are not readily available at the transmitter side. This is the case, for example, in the UAV scenario in which the UAV transmitter moves quickly, causing the channel conditions to vary in a very dynamic manner. This paper investigates a new NOMA downlink architecture, referred to as network-coded multiple access. In the absence of channel information, an NCMA transmitter allocates equal power to the superposed signals of different downlink users. A key challenge is how to achieve high NOMA throughput under such equal power allocation. Toward this end, NCMA makes joint use of physical-layer network coding (PNC) and multiuser decoding (MUD) together with a new superposition coding scheme, referred to as NCMA-based superposition coding. In NCMA-based superposition coding, equal powers are allocated to the signals of different users, but a relative phase offset between the signals is introduced to optimize PNC and MUD decodings. To demonstrate the feasibility and advantage of the NCMA downlink, we implemented our designs on a software-defined radio and UAV. Our experimental results show that NCMA is robust against varying channel conditions. Moreover, the throughput of NCMA can outperform the state-of-the-art

关键词： Non-orthogonal multiple access physical-layer network coding network-coded multiple access unmanned aerial vehicle implementation

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network-coded multiple access with High-Order Modulations

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2017年第11期66卷 9776-9792页

作者： Pan, Haoyuan Lu, Lu Liew, Soung Chang Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China Chinese Univ Hong Kong Inst Network Coding Hong Kong Hong Kong Peoples R China

This paper presents the first network-coded multiple access (NCMA) system prototype operated on high-order modulations up to 16-QAM. NCMA jointly exploits physical-layer network coding (PNC) and multiuser decoding (MUD) to boost throughput of multipacket reception systems. Direct generalization of the existing NCMA decoding algorithm, originally designed for BPSK, to high-order modulations, will lead to huge performance degradation. The throughput degradation is caused by the relative phase offset between received signals from different nodes. To circumvent the phase offset problem, this paper investigates an NCMA system with multiple receive antennas at the access point, referred to as MIMO-NCMA. We put forth a low-complexity symbol-level NCMA decoder that, together with MIMO, can substantially alleviate the performance degradation induced by relative phase offset. To demonstrate the feasibility and advantage of MIMO-NCMA for high-order modulations, we implemented our designs on software-defined radio. Our experimental results show that the throughput of QPSK MIMO-NCMA is double that of both BPSK NCMA and QPSK MUD at SNR = 10 dB. For higher signal-to-noise ratios at which 16-QAM can be supported, the throughput of MIMO-NCMA can be as high as 3.5 times that of BPSK NCMA. Overall, this paper provides an implementable framework for high-order modulated NCMA.

关键词： High-order modulation implementation multiple access multi-user detection network-coded multiple access physical-layer network coding

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Downlink network-coded multiple access with diverse power

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Digital Communications and networks 2024年第4期10卷 956-964页

作者： Bohao Cao Zheng Xiang Peng Ren Qiao Li Baoyi Xu School of Telecommunications Engineering Xidian UniversityXi'anShaanxi710071China

Normally,in the downlink network-coded multiple access(NCMA)system,the same power is allocated to different ***,equal power allocation is unsuitable for some scenarios,such as when user devices have different Quality of Service(QoS)***,we study the power allocation in the downlink NCMA system in this paper,and propose a downlink network-coded multiple access with Diverse Power(NCMA-DP),wherein different amounts of power are allocated to different *** terms of the Bit Error Rate(BER)of the multi-user decoder,and the number of packets required to correctly decode the message,the performance of the user with more allocated power is greatly improved compared to the Conventional NCMA(NCMA-C).Meanwhile,the performance of the user with less allocated power is still much better than ***,the overall throughput of NCMA-DP is greatly improved compared to that of *** simulation results demonstrate the remarkable performance of the proposed NCMA-DP.

关键词： network-coded multiple access Physical-layer network coding Multi-user decoder Power allocation Throughput Downlink network

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OTFS-Based Downlink network-coded multiple access With Joint Amplitude-Phase Design

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IEEE WIRELESS COMMUNICATIONS LETTERS 2024年第6期13卷 1576-1580页

作者： Ren, Peng Cao, Bohao Xiang, Zheng Yang, Long Xu, Baoyi Li, Yi Xidian Univ State Key Lab Integrated Serv Networks Xian 710071 Peoples R China

This letter designs an orthogonal time-frequency space (OTFS) enabled network-coded multiple access (NCMA) system for enhancing the throughput in high-mobility scenarios. For the designed system, the impact of power distribution and relative phase offset is theoretically analyzed and the upper-bound symbol error probability is derived into a closed-form expression. To further minimize the upper-bound symbol error probability, a joint amplitude-phase optimization scheme is proposed with using genetic algorithm. Finally, the simulation results reveal that the proposed scheme achieves significant throughput enhancement in high mobility scenarios.

关键词： Symbols Decoding Throughput Error probability Power distribution Downlink Doppler effect network-coded multiple access orthogonal time-frequency space high Doppler throughput power distribution coefficient relative phase offset

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Practical Power-Balanced Non-Orthogonal multiple access

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2017年第10期35卷 2312-2327页

作者： Pan, Haoyuan Lu, Lu Liew, Soung Chang Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China Chinese Acad Sci Technol & Engn Ctr Space Utilizat Beijing 100864 Peoples R China Chinese Univ Hong Kong Inst Network Coding Hong Kong Hong Kong Peoples R China

This paper is a theoretical-plus-experimental investigation of practical 5G strategies for power-balanced non-orthogonal multiple access (NOMA). By allowing multiple users to share the same time and frequency, NOMA can scale up the number of served users and increase spectral efficiency compared with existing OMA. Conventional NOMA schemes with successive interference cancellation (SIC) do not work well when users with comparable received powers transmit together. To allow power-balanced NOMA (more exactly, near power-balanced NOMA), this paper investigates a new NOMA architecture, named network-coded multiple access (NCMA). A distinguishing feature of NCMA is the joint use of physical-layer network coding (PNC) and multiuser decoding to boost NOMA throughputs. We first show that a simple NCMA architecture in which all users use the same modulation, referred to as rate-homogeneous NCMA, can achieve substantial throughput improvement over SIC-based NOMA under near power-balanced scenarios. Then, we put forth a new NCMA architecture, referred to as rate-diverse NCMA, in which different users may adopt different modulations commensurate with their relative SNRs. A challenge for rate-diverse NCMA is the design of a channel-coded PNC system. This paper is the first attempt to design channel-coded rate-diverse PNC. Experimental results on our software-defined radio prototype show that the throughput of rate-diverse NCMA can outperform the state-of-the-art rate-homogeneous NCMA by 80%. Overall, rate-diverse NCMA is a practical solution for near power-balanced NOMA.

关键词： Non-orthogonal multiple access physical-layer network coding network-coded multiple access 5G systems edge users implementation

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NO-V2X: Non-orthogonal multiple access with Side Information for V2X Communications 1

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European-Alliance-for-Innovation (EAI) International Conference on Smart Grid and Innovative Frontiers in Telecommunications (SmartGIFT)

作者： Situ, Zhenhui Ho, Ivan Wang-Hei Hong Kong Polytech Univ Dept Elect & Informat Engn Hung Hom Hong Kong Peoples R China Hong Kong Polytech Univ Shenzhen Res Inst Shenzhen Peoples R China

ISBN: (数字)9783319949659

ISBN: (纸本)9783319949659;9783319949642

We study a vehicle-to-everything (V2X) communication scenario where multiple vehicles coming from different road segments converge at a road junction and exchange their information via a road side unit. The high-mobility of vehicles determines that the communication is time-critical. If conventional orthogonal multiple access (OMA) is applied, not only the orthogonal resource allocation but also the scheduling overheads will incur significant delay. In addition, orthogonal domain may not be identified within short contact time among vehicles and the road-side unit. In contrast, non-orthogonal multiple access (NOMA) can provide low-delay and reliable communication by exploiting the overlapped or collided signals. In this paper, we investigate the application of NOMA with side information in V2X communications as the Non-orthogonal V2X (NO-V2X) scheme. NO-V2X takes the advantage of side information and physical-layer network coding (PNC) to increase the decoding success rate in the uplink phase and to reduce the required transmission power in the downlink phase. Our simulation results show that NO-V2X outperforms OMA and the conventional NOMA with successive interference cancellation (SIC).

关键词： Non-orthogonal multiple access V2X communication Side information Physical-layer network coding network-coded multiple access

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