Rate-Splitting Multiple Access: Unifying NOMA and SDMA in MISO VLC Channels

Naser, Shimaa; Sofotasios, Paschalis C.; Bariah, Lina; Jaafar, Wael; Muhaidat, Sami; Al‐Qutayri, Mahmoud; Dobre, Octavia A.

doi:10.1109/ojvt.2020.3031656

Cited by 54 publications

(35 citation statements)

References 133 publications

(210 reference statements)

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“…Nevertheless, the results can be extended to other metrics such as the weighted sumrate (WSR) and to other scenarios. Readers are invited to check [51] that confirms the inefficiency of NOMA and the superiority of RS from a WSR perspective, and are encouraged to consult the growing literature on RS (and RSMA) demonstrating the superiority of RS over NOMA and MU-LP in numerous scenarios and applications, namely multi-user multiantenna communications [51], [77], [83], multigroup multicast [39], [56], energy efficiency [78], [84], [85], multi-cell joint transmission [86], non-orthogonal unicast and multicast transmission [78], wireless information and power transfer [87], cooperative communication with user relaying [88], imperfect CSIT [89], [90], link-level simulations [91], C-RAN [92], secrecy rate [93], [94], aerial networks [85], [95], imperfect CSIT and CSIR [96], visible light communications [97], [98], network performance analysis [99], reconfigurable intelligent surface [100]. It would also be of interest for future work to understand how more recent MIMO NOMA schemes such as [67], [68] compare to RS [73], [75].…”

Section: Conclusion Future Research and Pathwaysmentioning

confidence: 99%

Is NOMA Efficient in Multi-Antenna Networks? A Critical Look at Next Generation Multiple Access Techniques

Clerckx

Mao

Schober

et al. 2021

IEEE Open J. Commun. Soc.

166

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In the past few years, a large body of literature has been created on downlink Non-Orthogonal Multiple Access (NOMA), employing superposition coding and Successive Interference Cancellation (SIC), in multi-antenna wireless networks. Furthermore, the benefits of NOMA over Orthogonal Multiple Access (OMA) have been highlighted. In this paper, we take a critical and fresh look at the downlink Next Generation Multiple Access (NGMA) literature. Instead of contrasting NOMA with OMA, we contrast NOMA with two other multiple access baselines. The first is conventional Multi-User Linear Precoding (MU-LP), as used in Space-Division Multiple Access (SDMA) and multi-user Multiple-Input Multiple-Output (MIMO) in 4G and 5G. The second, called Rate-Splitting Multiple Access (RSMA), is based on multi-antenna Rate-Splitting (RS). It is also a non-orthogonal transmission strategy relying on SIC developed in the past few years in parallel and independently from NOMA. We show that there is some confusion about the benefits of NOMA, and we dispel the associated misconceptions. First, we highlight why NOMA is inefficient in multi-antenna settings based on basic multiplexing gain analysis. We stress that the issue lies in how the NOMA literature, originally developed for single-antenna setups, has been hastily applied to multi-antenna setups, resulting in a misuse of spatial dimensions and therefore loss in multiplexing gains and rate. Second, we show that NOMA incurs a severe multiplexing gain loss despite an increased receiver complexity due to an inefficient use of SIC receivers. Third, we emphasize that much of the merits of NOMA are due to the constant comparison to OMA instead of comparing it to MU-LP and RS baselines. We then expose the pivotal design constraint that multi-antenna NOMA requires one user to fully decode the messages of the other users. This design constraint is responsible for the multiplexing gain erosion, rate and spectral efficiency loss, ineffectiveness to serve a large number of users, and inefficient use of SIC receivers in multi-antenna settings. Our analysis and simulation results confirm that NOMA should not be applied blindly to multi-antenna settings, highlight the scenarios where MU-LP outperforms NOMA and vice versa, and demonstrate the inefficiency, performance loss, and complexity disadvantages of NOMA compared to RSMA. The first takeaway message is that, while NOMA is suited for single-antenna settings (as originally intended), it is not efficient in most multi-antenna deployments. The second takeaway message is that another non-orthogonal transmission framework, based on RSMA, exists which fully exploits the multiplexing gain and the benefits of SIC to boost the rate and the number of users to serve in multi-antenna settings and outperforms both NOMA and MU-LP. Indeed, RSMA achieves higher multiplexing gains and rates, serves a larger number of users, is more robust to user deployments, network loads and inaccurate channel state information and has a lower receiver complexity than NOMA. Consequen...

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Section: Conclusion Future Research and Pathwaysmentioning

confidence: 99%

Is NOMA Efficient in Multi-Antenna Networks? A Critical Look at Next Generation Multiple Access Techniques

Clerckx

Mao

Schober

et al. 2021

IEEE Open J. Commun. Soc.

166

View full text Add to dashboard Cite

show abstract

“…Motivated by the strong interference management capability of RSMA in RF communications and the high operating SNR offered by VLC, the application of RSMA in MU-MIMO VLC is promising as RSMA achieves high DoF and SE gains over existing MA schemes. The authors of [120] and [121] were the first to study RSMA for MU-MIMO VLC. Both papers show clear sum-rate gains of RSMA over conventional MA schemes even when the user channels are highly correlated.…”

Section: ) Simultaneous Wireless Information and Power Transfer (Swipt)mentioning

confidence: 99%

“…1) Perfect CSIT: The precoder optimization for RSMA has been widely studied for perfect CSIT for different desgin objectives, such as maximizing the WSR [53], [89], [99]- [101], [104], [106], [112], [115], [117]- [121], [123], [139], [161], maximizing the minimum rate among users (max-min rate) [59], [103], [108], [110], [111], [132], maximizing the EE [74], [84], [94], [96], [102], [114], [122], [126], and minimizing the sum-power consumption [116], [124], [127]. For different design purposes, though the objective functions are different, the supplementary constraints introduced by RSMA are identical.…”

Section: A Precoder Optimizationmentioning

confidence: 99%

Rate-Splitting Multiple Access: Fundamentals, Survey, and Future Research Trends

Mao,

Dizdar,

Clerckx

et al. 2022

Preprint

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Rate-splitting multiple access (RSMA) has emerged as a novel, general, and powerful framework for the design and optimization of non-orthogonal transmission, multiple access (MA), and interference management strategies for future wireless networks. By exploiting splitting of user messages as well as non-orthogonal transmission of common messages decoded by multiple users and private messages decoded by their corresponding users, RSMA can softly bridge and therefore reconcile the two extreme interference management strategies of fully decoding interference and treating interference as noise. RSMA has been shown to generalize and subsume as special cases four existing MA schemes, namely, orthogonal multiple access (OMA), physical-layer multicasting, space division multiple access (SDMA) based on linear precoding (currently used in the fifth generation wireless network-5G), and non-orthogonal multiple access (NOMA) based on linearly precoded superposition coding with successive interference cancellation (SIC). Through information and communication theoretic analysis, RSMA has been shown to be optimal (from a Degrees-of-Freedom region perspective) in several transmission scenarios. Compared to the conventional MA strategies used in 5G, RSMA enables spectral efficiency (SE), energy efficiency (EE), coverage, user fairness, reliability, and quality of service (QoS) enhancements for a wide range of network loads (including both underloaded and overloaded regimes) and user channel conditions. Furthermore, it enjoys a higher robustness against imperfect channel state information at the transmitter (CSIT) and entails lower feedback overhead and complexity. Despite its great potential to fundamentally change the physical (PHY) layer and media access control (MAC) layer of wireless communication networks, RSMA is still confronted with many challenges on the road towards standardization. In this paper, we present the first comprehensive tutorial on RSMA by providing a survey of the pertinent state-ofthe-art research, detailing its architecture, taxonomy, and various appealing applications, as well as comparing with existing MA schemes in terms of their overall frameworks, performance, and complexities. An in-depth discussion of future RSMA research challenges is also provided to inspire future research on RSMAaided wireless communication for beyond 5G systems.

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“…Visible light communication (VLC) is envisioned to play a core role in future wireless networks as an efficient method to complement overcrowded radio frequency (RF) systems [1], [2]. Within this context, VLC utilizes the indoor light emitting diodes (LEDs) for both illumination and wireless data transmission [3].…”

Section: Introductionmentioning

confidence: 99%

An Effective Spatial Modulation Based Scheme for Indoor VLC Systems

et al. 2022

Self Cite

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We propose an enhanced spatial modulation (SM)based scheme for indoor visible light communication systems. This scheme enhances the achievable throughput of conventional SM schemes by transmitting higher order complex modulation symbol, which is decomposed into three different parts. These parts carry the amplitude, phase, and quadrant components of the complex symbol, which are then represented by unipolar pulse amplitude modulation (PAM) symbols. Superposition coding is exploited to allocate a fraction of the total power to each part before they are all multiplexed and transmitted simultaneously, exploiting the entire available bandwidth. At the receiver, a two-step decoding process is proposed to decode the active light emitting diode index before the complex symbol is retrieved. It is shown that at higher spectral efficiency values, the proposed modulation scheme outperforms conventional SM schemes with PAM symbols in terms of average symbol error rate (ASER), and hence, enhancing the system throughput. Furthermore, since the performance of the proposed modulation scheme is sensitive to the power allocation factors, we formulated an ASER optimization problem and propose a sub-optimal solution using successive convex programming (SCP). Notably, the proposed algorithm converges after only few iterations, whilst the performance with the optimized power allocation coefficients outperforms both random and fixed power allocation.

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Rate-Splitting Multiple Access: Unifying NOMA and SDMA in MISO VLC Channels

Cited by 54 publications

References 133 publications

Is NOMA Efficient in Multi-Antenna Networks? A Critical Look at Next Generation Multiple Access Techniques

Is NOMA Efficient in Multi-Antenna Networks? A Critical Look at Next Generation Multiple Access Techniques

Rate-Splitting Multiple Access: Fundamentals, Survey, and Future Research Trends

An Effective Spatial Modulation Based Scheme for Indoor VLC Systems

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