An optimized design of SCMA codebook based on star-QAM signaling constellations

Yu, Lisu; Lei, Xianfu; Fan, Pingzhi; Chen, Dageng

doi:10.1109/wcsp.2015.7341311

Cited by 84 publications

(83 citation statements)

References 10 publications

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“…More particularly, an optimized design of the mother-constellation based on the classic star-QAM signaling constellation has been proposed in [88]. The resultant simulation results showed that the star-QAM based codebooks are capable of significantly enhancing the BER performance of the square-QAM based codebooks.…”

Section: ) Sparse Code Multiple Access (Scma)mentioning

confidence: 99%

A Survey of Non-Orthogonal Multiple Access for 5G

Dai

Wang

Ding

et al. 2018

IEEE Commun. Surv. Tutorials

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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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Section: ) Sparse Code Multiple Access (Scma)mentioning

confidence: 99%

A Survey of Non-Orthogonal Multiple Access for 5G

Dai

Wang

Ding

et al. 2018

IEEE Commun. Surv. Tutorials

1,020

623

View full text Add to dashboard Cite

show abstract

“…Now, by substituting (26) into (10), as well as by exploiting the monotonicity of (10), we arrive at a plausible upper-bound of R 0 for the SCMA downlink in Rayleigh channels, which may be formulated as (27).…”

Section: N0mentioning

confidence: 99%

“…On the other hand, replacing R 0 by its upper bound of R 0 Upper given in (18) or (27) may result in predicting an optimistic data rate. As stated in Section I, the relationship between the cutoff rate and the system's capacity C obeys R 0 ≤ C. Hence, if the upper bound R 0 Upper we derived is sufficiently tight, it may only slightly exceed the value of R 0 and still be less than the system's capacity.…”

Section: Verification Of the Bounds Derivedmentioning

confidence: 99%

“…As a benefit of its remarkable capability of supporting rank-deficient multiuser communications, substantial efforts have been dedicated to further improving the SCMA technique [27]- [31]. For instance, Yu et al attempted to further narrow the performance discrepancy between the SCMA system and the single user system, employing more advanced lattices [27], while Xiao et al used more powerful iterative decoding algorithms [28].…”

Section: Introductionmentioning

confidence: 99%

“…For instance, Yu et al attempted to further narrow the performance discrepancy between the SCMA system and the single user system, employing more advanced lattices [27], while Xiao et al used more powerful iterative decoding algorithms [28]. As another important milestone, Chen et al further reduced the complexity [29], while the throughput of SCMA operating in downlink broadcast channels was studied by Nikopour et al [30].…”

Section: Introductionmentioning

confidence: 99%

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Cutoff Rate of Sparse Code Multiple Access in Downlink Broadcast Channels

Wang

et al. 2017

IEEE Trans. Commun.

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Abstract-For the sake of supporting massive connectivity in future 5G networks, non-orthogonal multiple access (NOMA) techniques are advocated. As a promising NOMA technique, in recent years sparse code multiple access (SCMA) has attracted substantial attention. However, there is a paucity of studies on the theoretical analysis of its error-freely achievable data rate, especially in the downlink context. Hence, we derive the cutoff rate of SCMA in downlink broadcast channels, which indicates the lower-bound of a system's errorfreely achievable rate. However, we will demonstrate that when considering the conventional categorization of pairwise error events, the accuracy of the cutoff rate rapidly degrades in the low-SNR region owing to the fact that multi-user SCMA systems typically encounter an extremely large constellation size. Alternatively, by invoking Bergmans' concept from 1973 in the categorization of pairwise error events, we obtain a more accurate cutoff rate both in the low-and the high-SNR regions. Moreover, we provide insights into the cutoff rate derivation process, which reveals some general guidelines for designing a beneficial codebook, capable of improving SCMA with respect to its original low-density signature (LDS) based counterpart.

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