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On the Use of PAM versus QAM Constellations in Rate-Splitting Multiple Access

IEEE WIRELESS COMMUNICATIONS LETTERS 2025年第3期14卷 921-925页

作者： Pendas-Recondo, Alvaro Lopez-Fernandez, Jesus Alberto Ayestaran, Rafael Gonzalez Univ Oviedo Dept Elect Engn Grp Signal Theory & Commun Gijon 33003 Spain

A comparison between the use of PAM and QAM constellations in Rate-Splitting Multiple Access (RSMA) is presented. Previous studies of RSMA with discrete or finite input signaling have considered either QAM or PSK. We propose the use of PAM constellations for every stream, with a phase rotation of 90 degrees applied to the common stream to achieve orthogonality with private streams. Numerical results based on data rate and Symbol Error Rate (SER) analysis indicate that PAM is superior to QAM when there is a significant disparity between channels for a two-user scenario. This finding indicates that PAM constellations can extend the operational region of RSMA over other Multiple Access (MA) strategies.

关键词： Rate-splitting multiple access (RSMA) multiple access (MA) multiantenna broadcast channel multiantenna broadcast channel discrete signaling discrete signaling finite input constellations finite input constellations superposition coding superposition coding superposition coding

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SPARC: superposition-Aided Rateless coding in Wireless Relay Systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2011年第9期60卷 4427-4438页

作者： Wang, Xijun Chen, Wei Cao, Zhigang Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

Energy accumulation and information accumulation are two approaches to exploit multiple transmissions in wireless relay systems. There is a tradeoff between energy accumulation and information accumulation from an outage perspective, in which a packet is successfully received if the channel capacity exceeds the transmission rate. However, how to strike a balance between these two approaches is still unknown. In this paper, we propose a new rateless-coding-based transmission scheme in wireless relay systems, where the relay superposes two rateless-coded packets generated from different codebooks to strike a balance between energy accumulation and information accumulation. We analyze the average end-to-end throughput of the proposed scheme and formulate an optimization problem to find the optimal power allocation ratio. Simulation results will validate our analysis and show that, compared with pure energy accumulation and pure information accumulation, our proposed scheme can achieve substantial throughput gain.

关键词： Cross-layer design rateless coding relay transmission superposition coding

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superposition Noisy Network coding

Superposition Noisy Network Coding

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IEEE International Symposium on Information Theory (ISIT)

作者： Ramalingam, Neevan Wang, Zhengdao Iowa State Univ Dept ECE Ames IA 50011 USA

ISBN: (纸本)9781457705953

We present a superposition coding scheme for communication over a network, which combines partial decode and forward with noisy network coding. This hybrid scheme is termed as superposition noisy network coding. The scheme is designed and analyzed for a single relay channel, single source multicast network and multiple source multicast network. The achievable rate region is determined for each case. The special cases of Gaussian single relay channel and two way relay channel are analyzed for superposition noisy network coding. The achievable rate of the proposed scheme is higher than the existing schemes of noisy network coding and compress-forward.

关键词： Decoding Encoding Gaussian channels Gaussian single relay channel Indexes Network coding Noise measurement Relays compress forward decode and forward communication decode and forward communication multicast communication multiple source multicast network network coding single source multicast network superposition coding superposition noisy network coding

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PLS of Relay-Aided VLC with RIS-Assisted Eavesdropper

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IEEE Transactions on Wireless Communications 2025年

作者： Amini, Changeez Azmi, Paeiz Kashef, Seyed Sadra Tarbiat Modares University Department of Electrical and Computer Engineering Tehran Iran Urmia University Department of Electrical and Computer Engineering Urmia Iran

In this paper, the physical layer security (PLS) in visible light communication (VLC) is investigated where the eavesdropper (ED) is assisted with the reconfigurable intelligent surface (RIS). Here, in the relay-aided system model, the ED is equipped with a new RIS type. The model also accounts for the received signal-dependent noise. For various trusted relaying schemes such as decode-and-forward (DF), amplify-and-forward (AF), and cooperative jamming (CJ), closed-form expressions of the lower and upper bounds on secrecy rate regions are derived under power constraints. Moreover, the effect of channel state information (CSI) uncertainty is analysed, as a practical condition. Considering this effect, it is demonstrated that the CJ scheme resists eavesdropping by increasing the noise and interference on the illegitimate user. The simulation results show that applying the RIS technique does not increase the signal-to-noise ratio of the ED in the CJ scheme in comparison with DF and AF schemes. © 2002-2012 IEEE.

关键词： Channel state information Physical layer security Reconfigurable intelligent surfaces superposition coding VLC

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Cooperative Medium Access Control Based on Spectrum Leasing

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2014年第1期63卷 297-307页

作者： Feng, Jiao Zhang, Rong Hanzo, Lajos Ng, Soon Xin Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

Based on cooperative spectrum leasing, a distributed "win-win" (WW) cooperative framework is designed to encourage the licensed source node (SN) to lease some part of its spectral resources to the unlicensed relay node (RN) for the sake of simultaneously improving the SN's achievable rate and for reducing the energy consumption (EC). The potential candidate RNs carry out autonomous decisions concerning whether to contend for a cooperative transmission opportunity, which could dissipate some of their battery power, while conveying their traffic in light of their individual service requirements. Furthermore, a WW cooperative medium-access-control (MAC) protocol is designed to implement the proposed distributed WW cooperative framework. Simulation results demonstrate that our WW cooperative MAC protocol is capable of providing both substantial rate improvements and considerable energy savings for the cooperative spectrum leasing system.

关键词： Cooperative MAC protocol energy efficiency greedy relay node spectrum leasing superposition coding throughput improvement

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Non-orthogonal Multiple Access (NOMA) with Successive Interference Cancellation for Future Radio Access

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IEICE TRANSACTIONS ON COMMUNICATIONS 2015年第3期E98B卷 403-414页

作者： Higuchi, Kenichi Benjebbour, Anass Tokyo Univ Sci Grad Sch Sci & Technol Dept Elect Engn Noda Chiba 2788510 Japan NTT DOCOMO INC Yokosuka Kanagawa 2398536 Japan

This paper presents our investigation of non-orthogonal multiple access (NOMA) as a novel and promising power-domain user multiplexing scheme for future radio access. Based on information theory, we can expect that NOMA with a successive interference canceller (SIC) applied to the receiver side will offer a better tradeoff between system efficiency and user fairness than orthogonal multiple access (OMA), which is widely used in 3.9 and 4G mobile communication systems. This improvement becomes especially significant when the channel conditions among the non-orthogonally multiplexed users are significantly different. Thus, NOMA can be expected to efficiently exploit the near-far effect experienced in cellular environments. In this paper, we describe the basic principle of NOMA in both the downlink and uplink and then present our proposed NOMA scheme for the scenario where the base station is equipped with multiple antennas. Simulation results show the potential system-level throughput gains of NOMA relative to OMA.

关键词： cellular system non-orthogonal multiple access superposition coding successive interference cancellation

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Exact Random coding Error Exponents of Optimal Bin Index Decoding

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IEEE TRANSACTIONS ON INFORMATION THEORY 2014年第10期60卷 6024-6031页

作者： Merhav, Neri Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

We consider ensembles of channel codes that are partitioned into bins, and focus on analysis of exact random coding error exponents associated with an optimum decoding of the index of the bin to which the transmitted codeword belongs. Two main conclusions arise from this analysis. First, for an independent random selection of codewords within a given type class, the random coding exponent of an optimal bin index decoding is given by the ordinary random coding exponent function, computed at the rate of the entire code, independently of the exponential rate of the size of the bin. Second, for this ensemble of codes, suboptimal bin index decoding, which is based on an ordinary maximum likelihood decoding, is as good as the optimal bin index decoding in terms of the random coding error exponent achieved. Finally, for the sake of completeness, we also outline how our analysis of exact random coding exponents extends to the hierarchical ensemble that correspond to superposition coding and optimal decoding, where for each bin, first, a cloud center is drawn at random, and then the codewords of this bin are drawn conditionally indepenently given the cloud center. For this ensemble, the two conclusions, mentioned above, no longer hold necessarily in general.

关键词： Random coding error exponent binning broadcast channels superposition coding

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Energy Efficient Cooperative Strategies for Relay-Assisted Downlink Cellular Systems

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2014年第11期32卷 2075-2089页

作者： Rini, Stefano Kurniawan, Ernest Ghaghanidze, Levan Goldsmith, Andrea Tech Univ Munich Inst Commun Engn D-80290 Munich Germany Tech Univ Munich D-80290 Munich Germany Stanford Univ Dept Elect Engn Stanford CA 94305 USA Stanford Univ Sch Engn Stanford CA 94305 USA Stanford Univ Stanford CA 94305 USA

The impact of cognitive radio techniques on the energy efficiency of a downlink cellular system in which multiple relays assist the transmission of the base station toward multiple receivers is studied. In particular, the fundamental tradeoff between the power consumption at the base station and the level of cooperation at the relay nodes is investigated. By increasing its transmit power, the base station can distribute the same message to multiple relays. In turn, the common knowledge at the relays enables cooperation, which results in a reduction in the power consumption due to interference management and coherent combining gains. This implies that the overall power efficiency can potentially be improved by an increase in the power consumption at the base station. We employ an information-theoretical analysis of the attainable power efficiency based on the chain graph representation of achievable schemes. This novel theoretical tool uses a graphical Markov model to represent coding operations and allows for the automatic derivation of achievable rate regions for general networks. This approach provides an effective tool to analyze the relationship between the energy consumption at the base station and power savings provided by relay cooperation through the use of transmission strategies such as superposition coding, interference decoding and rate-splitting. We present numerical evaluations for the scenario in which two relay nodes aid the communication between the base station and three receivers. These evaluations show that cooperative strategies at the relays provide clear advantages as compared to the non-cooperative scenario for varying channel conditions and target rates.

关键词： Energy efficiency Relay network Downlink cellular system superposition coding Interference decoding Rate-splitting

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Layered coding for Interference Channels With Partial Transmitter Side Information

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IEEE TRANSACTIONS ON INFORMATION THEORY 2011年第5期57卷 2765-2780页

作者： Thejaswi, P. S. Chandrashekhar Bennatan, Amir Zhang, Junshan Calderbank, A. Robert Cochran, Douglas Arizona State Univ Sch Elect Comp & Energy Engn Tempe AZ 85287 USA Princeton Univ Program Appl & Computat Math PACM Princeton NJ 08544 USA

A two-user interference channel is considered where each transmitter has access to a part of the information intended to the other destination. A primary objective is to maximize the information rates, by exploring the cooperation between the transmitters for interference mitigation, based on the partial side information. It is clear that full cooperation between the transmitters is not possible since each transmitter has only a part of the side information. With this insight, several "layered coding" schemes, consisting of binning and superposition at different stages, are developed. These schemes are are carefully built on coding strategies for the classical interference channel and node cooperation mechanisms. In particular, two layered coding schemes, which are based on a combination of MIMO broadcast coding and the Han-Kobayashi (HK) coding, are thoroughly studied : The first one, namely layered coding with binning, makes heavy use of the Gelfand-Pinsker binning and the HK coding and the second one, namely layered superposition coding, involves superposition coding over different tiers. Rate regions corresponding to the proposed schemes are derived. Then the application of these coding schemes are illustrated for the Gaussian case and numerical results corroborate that the proposed layered coding schemes yield substantial gains at high SNR.

关键词： Beamforming binning dirty paper coding distributed MIMO interference channels side information superposition coding

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Two-Layered superposition of Broadcast/Multicast and Unicast Signals in Multiuser OFDMA Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2020年第2期19卷 979-994页

作者： Vargas, David Kim, Yong Jin Daniel BBC Res & Dev London W12 7TQ England Rose Hulman Inst Technol Dept Elect & Comp Engn Terre Haute IN 47803 USA

We study optimal delivery strategies of one common and ${K}$ independent messages from a source to multiple users in wireless environments. In particular, two-layered superposition of broadcast/multicast and unicast signals is considered in a downlink multiuser OFDMA system. In the literature and industry, the two-layer superposition is often considered as a pragmatic approach to make a compromise between the simple but suboptimal orthogonal multiplexing (OM) and the optimal but complex fully-layered non-orthogonal multiplexing. In this work, we show that only two-layers are necessary to achieve the maximum sum-rate when the common message has higher priority than the ${K}$ individual unicast messages, and OM cannot be sum-rate optimal in general. We develop an algorithm that finds the optimal power allocation over the two-layers and across the OFDMA radio resources in static channels and a class of fading channels. Two main use-cases are considered: i) Multicast and unicast multiplexing when ${K}$ users with uplink capabilities request both common and independent messages, and ii) broadcast and unicast multiplexing when the common message targets receive-only devices and ${K}$ users with uplink capabilities additionally request independent messages. Finally, we develop a transceiver design for broadcast/multicast and unicast superposition transmission based on LTE-A-Pro physical layer and show with numerical evaluations in mobile environments with multipath propagation that the capacity improvements can be translated into significant practical performance gains compared to the orthogonal schemes in the 3GPP specifications. The impact of real channel estimation is also analyzed and it is shown that significant gains in terms of spectral efficiency or increased coverage area are still available even in the presence of estimation errors and imperfect interference cancellation for the two-layered superposition system.

关键词： Broadcast multicast unicast channel capacity OFDMA non-orthogonal multiplexing superposition coding successive cancellation LTE-Advanced Pro 5G new radio

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