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Success Probability and Area Spectral Efficiency in SCMA Wireless Networks

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2018年第8期67卷 7764-7768页

作者： Liu, Lei Sheng, Min Liu, Junyu Wang, Xijun Li, Jiandong Xidian Univ State Key Lab Integrated Serv Networks ISN Xian 710071 Shaanxi Peoples R China

sparse code multiple access (SCMA) is emerging as a promising multiple access technology for the fifth-generation wireless networks. By leveraging user-specific SCMA codebooks, SCMA possesses the potential to enable non-orthogonal resource access, and thus leading to the overloading gain. Benefiting from this, SCMA can accommodate more users and achieve a higher throughput than orthogonal frequency division multiple access. In this correspondence, we propose a tractable analytical framework using tools from stochastic geometry to investigate the performance of SCMA wireless networks. In particular, we obtain explicit closed-form expressions for the success probability and the area spectral efficiency (ASE). Based on the derived results, we prove that the ASE is a quasi-concave function of the transmitter density. Moreover, we shed light on the impact of SCMA code-word dimension K and the number of non-zero entries in SCMA codeword N on the network performance. Specifically, we demonstrate that the optimal transmitter density and the maximum ASE scale super-linearly with rate K-N. Simulation results validate the accuracy of the presented analysis and exhibit the superiority of SCMA.

关键词： sparse code multiple access success probability area spectral efficiency stochastic geometry

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On Fixed-Point Implementation of Log-MPA for SCMA Signals

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IEEE WIRELESS COMMUNICATIONS LETTERS 2016年第3期5卷 324-327页

作者： Liu, Jiaqi Wu, Gang Li, Shaoqian Tirkkonen, Olav Univ Elect Sci & Technol China Natl Key Lab Sci & Technol Commun Chengdu 611731 Peoples R China Aalto Univ Dept Commun & Networking FI-00076 Aalto Finland

In this letter, we present a design framework for fixed-point implementation of the log-domain message passing algorithm (Log-MPA) for sparse code multiple access signals, and make a detailed comparative analysis on the complexity of Log-MPA and traditional MPA. We also investigate the impact of the number of massage-passing iterations within the Log-MPA decoding process on the performance of Log-MPA. Simulation results demonstrate that Log-MPA achieves favorable performance with low-complexity hardware implementation as compared to MPA. We also implement Log-MPA on FPGA evaluation board to verify the performance of Log-MPA.

关键词： sparse code multiple access iterative decoding massage passing log-Likehood ratio bipartite graph

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Gaussian Approximation-Based Belief Propagation Receiver for Uplink SCMA Systems With Imperfect CSIR

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IEEE COMMUNICATIONS LETTERS 2018年第12期22卷 2611-2614页

作者： Lim, Seung-Chan Park, Hyuncheol Korea Adv Inst Sci & Technol Sch Elect Engn Daejeon 34141 South Korea

For uplink sparse code multiple access (SCMA) systems, a channel estimation is required to support a multi-user detection in practice. Motivated by the conventional detection, called a Gaussian approximation-based belief propagation (GA-BP) with matched filtering, we propose an efficient receiver suitable for the uplink SCMA systems when exact channel state information is not available. By estimating matched filtered channels (rather than explicitly estimating actual channels), the proposed methods efficiently support the second-stage GA-BP detector with negligible increment of complexity. The simulation results show that the proposed receiver achieves the similar estimation and detection performance to the state-of-the-art receiver while the required complexity can be drastically reduced.

关键词： sparse code multiple access multi-user detection channel estimation belief propagation Gaussian approximation

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SCMA Receiver Design for Cellular Uplink Transmission Coexisted with D2D 11

SCMA Receiver Design for Cellular Uplink Transmission Coexis...

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11th IEEE International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Liu, Yukai Chen, Wen Wei, Fan Labeau, Fabrice Shanghai Jiao Tong Univ Dept Elect Engn Shanghai Inst Adv Com & Data Sci Minhang 200240 Peoples R China McGill Univ Dept Elect & Comp Engn 3480 Univ St Montreal PQ H3A 0E9 Canada

ISBN: (纸本)9781728135557

sparse code multiple access (SCMA) is one of the most concerned non-orthogonal multiple access schemes in 5G communication system. Meanwhile, device-to-device (D2D) communication is also one of the key technologies for 5G network to improve the spectral efficiency. In cellular systems with SCMA, the non-orthogonal nature renders resource blocks support for more users so that an overloaded system can be achieved. To further improve the system capacity, a D2D and uplink cellular coexisting network is proposed in this paper. The interference between D2D and cellular users are handled. Since conventional message passing algorithm (MPA) has the exponential complexity, the receiver for cellular users is based on some low complexity methods and that for D2D users is also associated with this method. Simulation results show that the proposed hybrid network has an acceptable BER performance loss compared to the general uplink SCMA system, while the proposed SCMA receiver can reduce the decoding complexity significantly compared to the conventional MPA.

关键词： device-to-device communication sparse code multiple access hybrid network low complexity decoder

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A Review of recent developments in NOMA & SCMA schemes for 5G Technology 16

A Review of recent developments in NOMA & SCMA schemes for 5...

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16th International Symposium on Distributed Computing and Applications to Business, Engineering and Science (DCABES)

作者： Alshammary, Miznah Alanezi, Fahad Kings Coll London Dept Comp Sci London England Bedfordshire Univ Dept Comp Sci London England

ISBN: (纸本)9781538621622

The race for developing 5G technology has taken a multi-organizational competition in the recent past, where the professional bodies, private organizations, and research units are carrying out research in developing various technologies relating to 5G. multiple access Scheme is one of the most important aspects that have been an area of interest for the majority as 5G is expected to accommodate large number of users with high speed of data transmission. This paper review the latest developments in the field of research concerning sparse code multiple access (SCMA) and Non-orthogonal multiple access (NOMA). Ann extensive research has been carried out to identify the recent developments and their results are presented in this paper. This study has found that most of the recent developments in SCMA were focusing on achieving lower complexity levels, low BER, and effective and efficient energy utilization, and the recent developments identified regarding NOMA focused especially on the performance attributes like spectral efficiency, spatial efficiency, low BER and latency, and resource allocation and multiple access.

关键词： sparse code multiple access Non-orthogonal multiple access 5g Technology

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A High Performance Joint Detection and Decoding scheme for LDPC coded SCMA system

A High Performance Joint Detection and Decoding scheme for L...

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IEEE-Communications-Society Global Communications Conference on Trusted Communications with Physical Layer Security (IEEE GLOBECOM)

作者： Han, Kaining Zhang, Zhenbing Hu, Jianhao Chen, Jienan Univ Elect Sci & Technol China Natl Key Lab Commun Chengdu Sichuan Peoples R China

ISBN: (纸本)9781509024827

sparse code multiple access (SCMA) is a promising candidate multiple access technology for the fifth generation (5G) mobile communication system. In this paper, we propose a factor graph based high performance Joint Detection and Decoding scheme (JDD) for the Low Density Parity Check code (LDPC) coded SCMA system. Also, we propose a message damping aided reduced complexity JDD scheme (RC-JDD) to achieve a lower complexity. According to the simulation results, the proposed JDD scheme has 2.6dB Bit Error Rate (BER) performance gain compared with the traditional methods and approximates to the single user detection performance bound with only 0.5dB loss. The RC-JDD scheme has only 10% complexity of JDD scheme with only 0.5dB loss. Thus the proposed RC-JDD scheme can be a good candidate for 5G system.

关键词： Joint Detection and Decoding sparse code multiple access Low Density Parity Check code 5G

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A Low Complexity Joint Iterative Multi-User Detection Decoding Receiver Based on Verified Message

A Low Complexity Joint Iterative Multi-User Detection Decodi...

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IEEE/CIC International Conference on Communications in China (ICCC)

作者： Miao, Jiansong Hu, Xuejia Li, Weijie Li, Hairui Beijing Univ Posts & Telecommun Beijing Lab Adv Informat Networks Beijing Peoples R China

ISBN: (纸本)9781728173276

The sparse code multiple access technology and polar code technology can meet the functional requirements of the three major scenarios of 5G. A SCMA system receiver can combine a multi-user detector with a polar code decoder, but it requires high computational complexity to obtain the ideal bit error rate (BER) performance. This paper proposes a joint iterative detection and decoding receiver (VJDD) scheme for transmitting verified messages based on a serial structure. This solution improves the iterative convergence speed of the receiver by transmitting verified messages to each node in the factor graph in time. Simulation results show that the VJDD scheme can reduce the computational complexity of the receiver on the premise of ensuring the performance of the receiver.

关键词： sparse code multiple access multi-user detection polar code joint detection and decoding

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A Comparative Study on the Capacity of SCMA and LDSMA 14

A Comparative Study on the Capacity of SCMA and LDSMA

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14th IEEE International Wireless Communications and Mobile Computing Conference (IWCMC)

作者： Chen, Shuang Peng, Kewu Zhang, Yushu Song, Jian Tsinghua Univ Dept Elect Engn Beijing Natl Res Ctr Informat Sci & Technol Beijing 100084 Peoples R China

ISBN: (纸本)9781538620700

sparse code multiple access (SCMA) is a newly proposed non-orthogonal multiple access technique for the 5th generation (5G) of wireless communication systems. It improves low-density signature multiple access (LDSMA) by replacing the inherent repetition code with multi-dimensional constellations. In this paper, the Gaussian-input channel capacities as well as the constellation constrained (CC) capacities of SCMA and LDSMA are analyzed and compared for the cases of Gaussian multiple access channel (GMAC) with random phase rotation and GMAC with fast fading, which disclose the performance potential of SCMA over LDSMA.

关键词： non-orthogonal multiple access sparse code multiple access low-density signature multiple access channel capacity constellation constrained capacity

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Active User Detection of Uplink Grant-Free SCMA in Frequency Selective Channel 87

Active User Detection of Uplink Grant-Free SCMA in Frequency...

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87th IEEE Vehicular Technology Conference (VTC-Spring)

作者： Wang, Feilong Zhang, Yuyan Zhao, Hui Huang, Hanyuan Li, Jing BUPT Intelligent Comp & Commun Lab Key Lab Universal Wireless Commun Minist Educ Beijing Peoples R China

ISBN: (纸本)9781538663554

Massive machine type communication (mMTC) is one of the three fifth generation mobile networking (5G) key usage scenarios, which is characterized by a very large number of connected devices typically transmitting a relatively low volume of non-delay sensitive data. To support the mMTC communication, an uplink (UL) grant-free sparse code multiple access (SCMA) system has been proposed. In this system, the knowledge of user equipments' (UEs') status should be obtained before decoding the data by a message passing algorithm (MPA). An existing solution is to use the compressive sensing (CS) theory to detect active UEs under the assumed condition of flat fading channel. But the assumed condition is not suitable for the frequency selective channel and will decrease the accuracy of active UEs detection. This paper proposes a new simple module named refined active UE detector (RAUD), which is based on frequency selective channel gain analyzing. By making full use of the channel gain and analyzing the difference between characteristic values of the two status of UEs, RAUD module can enhance the active UEs detection accuracy. Meanwhile, the addition of the proposed module has a negligible effect on the complexity of UL grant-free SCMA receiver.

关键词： sparse code multiple access Uplink grant-free Active user equipments detection

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Low-Complexity Detectors for Uplink SCMA: Symbol Flipping and Dynamic Partial Marginalization-Based MPA 87

Low-Complexity Detectors for Uplink SCMA: Symbol Flipping an...

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87th IEEE Vehicular Technology Conference (VTC-Spring)

作者： Wei, Li Huang, Bo Zheng, Jianping Xidian Univ State Key Lab Integrated Serv Networks Xian Peoples R China

ISBN: (纸本)9781538663554

In this paper, two low-complexity detectors for uplink sparse code multiple access (SCMA) systems are proposed. The first, called symbol flipping algorithm (SFA), is an analogy of the bit-flipping decoding algorithm in the low-density parity check code field. Specifically, the local hard-decision detection is first performed at each resource node, and the decided signal in the least reliable resource node is flipped. The second is an improved partial marginalization (PM)-based message passing algorithm (MPA). Based on the reliability definition introduced in SFA, the variable nodes to be marginalized are determined dynamically during the MPA iteration procedure, and the resulted detector is termed as dynamic PM-based MPA. Simulation results show that the proposed hard-decision SFA can achieve a numerous complexity reduction and the proposed dynamic PM-based MPA has better performance than the conventional PM-based MPA.

关键词： sparse code multiple access multi-user detection bit flipping message passing algorithm complexity

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