Information Theoretic Analysis of LDS Scheme

Razavi, Razieh; Hoshyar, Reza; Imran, Muhammad Ali; Wang, Y.

doi:10.1109/lcomm.2011.061011.102098

Cited by 54 publications

(30 citation statements)

References 8 publications

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“…In contrast, code-domain NOMA utilizes user-specific spreading sequences that are either sparse sequences or non-orthogonal cross-correlation sequences of low correlation coefficient. This can be further divided into a few different classes, such as low-density spreading CDMA (LDS-CDMA) [4,5], low-density spreading-based OFDM (LDS-OFDM) [6,7], and sparse code multiple access (SCMA) [8,9]. The use of low-density spreading sequences helps LDS-CDMA to limit the impact of interference on each chip of basic CDMA systems.…”

Section: Basic Concepts Of Nomamentioning

confidence: 99%

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Power-Domain Non-Orthogonal Multiple Access (NOMA) in 5G Systems: Potentials and Challenges

Islam

Avazov

Dobre

et al. 2017

IEEE Commun. Surv. Tutorials

2,102

1,162

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Abstract-Non-orthogonal multiple access (NOMA) is one of the promising radio access techniques for performance enhancement in next-generation cellular communications. Compared to orthogonal frequency division multiple access (OFDMA), which is a well-known high-capacity orthogonal multiple access (OMA) technique, NOMA offers a set of desirable benefits, including greater spectrum efficiency. There are different types of NOMA techniques, including power-domain and code-domain. This paper primarily focuses on power-domain NOMA that utilizes superposition coding (SC) at the transmitter and successive interference cancellation (SIC) at the receiver. Various researchers have demonstrated that NOMA can be used effectively to meet both network-level and user-experienced data rate requirements of fifth-generation (5G) technologies. From that perspective, this paper comprehensively surveys the recent progress of NOMA in 5G systems, reviewing the state-of-the-art capacity analysis, power allocation strategies, user fairness, and user-pairing schemes in NOMA. In addition, this paper discusses how NOMA performs when it is integrated with various proven wireless communications techniques, such as cooperative communications, multiple-input multiple-output (MIMO), beamforming, space-time coding, and network coding, among others. Furthermore, this paper discusses several important issues on NOMA implementation and provides some avenues for future research. I. INTRODUCTIONFrom analog phone calls through to all Internet Protocol services, including voice and messaging, each transition has been encouraged by the need to meet the requirements of the new generation of mobile technology. Subsequently, mobile communications technology is presently facing a new challenge, giving birth to a hyper-connected society through the emergence of fifth-generation (5G) services. With enormous potential for both consumers and industry, 5G is expected to roll out by 2020. From the next-generation radio access technology viewpoint, a step change in data speed and a significant reduction in end-to-end latency is a major concern for 5G, since the rapid development of the mobile Internet and the Internet of Things (IoT) exponentially accelerates the demand for high data-rate applications. In particular, many of the industry initiatives that have progressed with work on 5G declare that the network-level data rate in 5G should be 10-20 Gbps (that is, 10-20 times the peak data rate in 4G), and the user-experienced data rate should be 1 Gbps (100 times the user-experienced data rate in 4G). They also set the latency (end-to-end round-trip delay) at 1 millisecond (one-fifth of the latency in 4G).The underlying physical connection in a cellular network is called radio access technology, which is implemented by a radio access network (RAN). A RAN basically utilizes a channel access technique to provide the mobile terminals with a connection to the core network. The design of a suitable multiple access technique is one of the most important aspects in improvi...

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Section: Basic Concepts Of Nomamentioning

confidence: 99%

“…For user 1, SIC is not executed, and the signal is directly decoded. Thus, the achievable data rate for user 1 and user 2 are given by (5) and (6), respectively.…”

mentioning

confidence: 99%

Power-Domain Non-Orthogonal Multiple Access (NOMA) in 5G Systems: Potentials and Challenges

Islam

Avazov

Dobre

et al. 2017

IEEE Commun. Surv. Tutorials

2,102

1,162

View full text Add to dashboard Cite

show abstract

“…However, the key difference compared to CDMA is that the spreading sequences are restricted to sparse sequences or non-orthogonal low cross-correlation sequences in NOMA. In this subsection, we first present the initial form of NOMA based on sparse spreading sequences, i.e., LDS-CDMA [64]- [67]. Then, the family of LDS aided multi-carrier OFDM systems (LDS-OFDM) [68]- [73] will be discussed, which retains all the benefits of OFDM-based multi-carrier transmissions in terms of its ISI avoidance, together with MUD-assisted LDS-CDMA operating at a lower complexity than that of the optimal maximum a posteriori probability (MAP) detector.…”

Section: B Code-domain Nomamentioning

confidence: 99%

“…On the other hand, a structured approach of designing LDS codes for LDS-CDMA has been proposed in [66], where the basic idea is to map the signature constellation elements to the spreading matrix hosting the spreading sequences. Furthermore, the capacity region of LDS-CDMA was calculated using information theoretic analysis in [67], and the accompanying simulation results showed how the attainable capacity depended on the spreading sequence density factor as well as on the maximum number of users associated with each chip, which provided insightful theoretical guidelines for practical LDS system designs.…”

Section: B Code-domain Nomamentioning

confidence: 99%

A Survey of Non-Orthogonal Multiple Access for 5G

Dai

Wang

Ding

et al. 2018

IEEE Commun. Surv. Tutorials

1,127

664

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Abstract-In the 5th generation (5G) of wireless communication systems, hitherto unprecedented requirements are expected to be satisfied. As one of the promising techniques of addressing these challenges, non-orthogonal multiple access (NOMA) has been actively investigated in recent years. In contrast to the family of conventional orthogonal multiple access (OMA) schemes, the key distinguishing feature of NOMA is to support a higher number of users than the number of orthogonal resource slots with the aid of non-orthogonal resource allocation. This may be realized by the sophisticated inter-user interference cancellation at the cost of an increased receiver complexity. In this article, we provide a comprehensive survey of the original birth, the most recent development, and the future research directions of NOMA. Specifically, the basic principle of NOMA will be introduced at first, with the comparison between NOMA and OMA especially from the perspective of information theory. Then, the prominent NOMA schemes are discussed by dividing them into two categories, namely, power-domain and code-domain NOMA. Their design principles and key features will be discussed in detail, and a systematic comparison of these NOMA schemes will be summarized in terms of their spectral efficiency, system performance, receiver complexity, etc. Finally, we will highlight a range of challenging open problems that should be solved for NOMA, along with corresponding opportunities and future research trends to address these challenges.

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“…When the receiver can perfectly obtain the channel knowledge H, the non-orthogonal multiple access capacity region C(U 0 ) can be expressed as [7],…”

Section: B Capacity Region and Per-user Outage Definitionmentioning

confidence: 99%

Sparse code multiple access: An energy efficient uplink approach for 5G wireless systems

Zhang

Lü

et al. 2014

2014 IEEE Global Communications Conference

192

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The rapid traffic growth and ubiquitous access requirements make it essential to explore the next generation (5G) wireless communication networks. In the current 5G research area, non-orthogonal multiple access has been proposed as a paradigm shift of physical layer technologies. Among all the existing non-orthogonal technologies, the recently proposed sparse code multiple access (SCMA) scheme is shown to achieve a better link level performance. In this paper, we extend the study by proposing an unified framework to analyze the energy efficiency of SCMA scheme and a low complexity decoding algorithm which is critical for prototyping. We show through simulation and prototype measurement results that SCMA scheme provides extra multiple access capability with reasonable complexity and energy consumption, and hence, can be regarded as an energy efficient approach for 5G wireless communication systems.Index Terms-5G, sparse code multiple access (SCMA), energy efficiency, non-orthogonal multiple access, low complexity implementation, prototype

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Information Theoretic Analysis of LDS Scheme

Cited by 54 publications

References 8 publications

Power-Domain Non-Orthogonal Multiple Access (NOMA) in 5G Systems: Potentials and Challenges

Power-Domain Non-Orthogonal Multiple Access (NOMA) in 5G Systems: Potentials and Challenges

A Survey of Non-Orthogonal Multiple Access for 5G

Sparse code multiple access: An energy efficient uplink approach for 5G wireless systems

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