60 GHz MAC Standardization: Progress and Way Forward

Communication at mmWave frequencies has been the focus in the recent years. In this paper, we discuss standardization efforts in 60 GHz short range communication and the progress therein. We compare the available standards in terms of network architecture, medium access control mechanisms, physical layer techniques and several other features. Comparative analysis indicates that IEEE 802.11ad is likely to lead the short-range indoor communication at 60 GHz. We bring to the fore resolved and unresolved issues pertaining to robust WLAN connectivity at 60 GHz. Further, we discuss the role of mmWave bands in 5G communication scenarios and highlight the further efforts required in terms of research and standardization

Improved Decoding of Staircase Codes: The Soft-aided Bit-marking (SABM) Algorithm

Staircase codes (SCCs) are typically decoded using iterative bounded-distance decoding (BDD) and hard decisions. In this paper, a novel decoding algorithm is proposed, which partially uses soft information from the channel. The proposed algorithm is based on marking certain number of highly reliable and highly unreliable bits. These marked bits are used to improve the miscorrection-detection capability of the SCC decoder and the error-correcting capability of BDD. For SCCs with $2$-error-correcting Bose-Chaudhuri-Hocquenghem component codes, our algorithm improves upon standard SCC decoding by up to $0.30$~dB at a bit-error rate (BER) of $10^{-7}$. The proposed algorithm is shown to achieve almost half of the gain achievable by an idealized decoder with this structure. A complexity analysis based on the number of additional calls to the component BDD decoder shows that the relative complexity increase is only around $4\%$ at a BER of $10^{-4}$. This additional complexity is shown to decrease as the channel quality improves. Our algorithm is also extended (with minor modifications) to product codes. The simulation results show that in this case, the algorithm offers gains of up to $0.44$~dB at a BER of $10^{-8}$.Comment: 10 pages, 12 figure

Threshold-Based Fast Successive-Cancellation Decoding of Polar Codes

Fast SC decoding overcomes the latency caused by the serial nature of the SC decoding by identifying new nodes in the upper levels of the SC decoding tree and implementing their fast parallel decoders. In this work, we first present a novel sequence repetition node corresponding to a particular class of bit sequences. Most existing special node types are special cases of the proposed sequence repetition node. Then, a fast parallel decoder is proposed for this class of node. To further speed up the decoding process of general nodes outside this class, a threshold-based hard-decision-aided scheme is introduced. The threshold value that guarantees a given error-correction performance in the proposed scheme is derived theoretically. Analysis and hardware implementation results on a polar code of length $1024$ with code rates $1/4$, $1/2$, and $3/4$ show that our proposed algorithm reduces the required clock cycles by up to $8\%$, and leads to a $10\%$ improvement in the maximum operating frequency compared to state-of-the-art decoders without tangibly altering the error-correction performance. In addition, using the proposed threshold-based hard-decision-aided scheme, the decoding latency can be further reduced by $57\%$ at $\mathrm{E_b}/\mathrm{N_0} = 5.0$~dB.Comment: 14 pages, 8 figures, 5 tables, submitted to IEEE Transactions on Communication

Implementation of a High-Throughput Fast-SSC Polar Decoder with Sequence Repetition Node

Even though polar codes were adopted in the latest 5G cellular standard, they still have the fundamental problem of high decoding latency. Aiming at solving this problem, a fast simplified successive cancellation (Fast-SSC) decoder based on the new class of sequence repetition (SR) nodes has been proposed recently in \cite{sr2020} and has a lower required number of time steps than other existing Fast-SSC decoders in theory. This paper focuses on the hardware implementation of this SR node-based fast-SSC (SRFSC) decoder. The implementation results for a polar code with length 1024 and code rate 1/2 show that our implementation has a throughput of $505$ Mbps on an Altera Stratix IV FPGA, which is 17.9% higher with respect to the previous work.Comment: 6 pages, 6 figures. Accepted and to appear in IEEE International Workshop on Signal Processing Systems, Oct 2020 (SIPS2020). The latest version. arXiv admin note: text overlap with arXiv:2005.0439

Multifunctional photonic integrated circuit for diverse microwave signal generation, transmission and processing

Microwave photonics (MWP) studies the interaction between microwave and optical waves for the generation, transmission and processing of microwave signals (i.e., three key domains), taking advantages of broad bandwidth and low loss offered by modern photonics. Integrated MWP using photonic integrated circuits (PICs) can reach a compact, reliable and green implementation. Most PICs, however, are recently developed to perform one or more functions restricted inside a single domain. In this paper, as highly desired, a multifunctional PIC is proposed to cover the three key domains. The PIC is fabricated on InP platform by monolithically integrating four laser diodes and two modulators. Using the multifunctional PIC, seven fundamental functions across microwave signal generation, transmission and processing are demonstrated experimentally. Outdoor field trials for electromagnetic environment surveillance along an in-service high-speed railway are also performed. The success to such a PIC marks a key step forward for practical and massive MWP implementations.Comment: 17 page

Adaptive beamforming for optical wireless communication via fiber modal control

High-speed optical wireless communication can address the exponential growth in data traffic. Adaptive beamforming customized for the target location is crucial, but existing solutions such as liquidcrystal spatial light modulators and microelectromechanical systems require costly micro/nano manufacturing, delicate alignment, and a high degree of mechanical stability. These challenges reflect the fragility of integrating a fiber network with micro/nano mechanical or photonic systems. Here, we realize low-cost, low-loss, and fiber-compatible beamforming and continuous beam steering through controlled bending of a multi-mode fiber that modifies its modal coupling, and use it to enable flexible optical wireless communication at 10 Gb/s. By using the fiber modal coupling as degrees of freedom rather than an impediment, this approach offers a promising solution for flexible and cost-effective optical wireless communication networks.Comment: 17 pages, 7 figure

Inverse design for material anisotropy and its application for a compact X-cut TFLN on-chip wavelength demultiplexer

Inverse design focuses on identifying photonic structures to optimize the performance of photonic devices. Conventional scalar-based inverse design approaches are insufficient to design photonic devices of anisotropic materials such as lithium niobate (LN). To the best of our knowledge, this work proposes for the first time the inverse design method for anisotropic materials to optimize the structure of anisotropic-material based photonics devices. Specifically, the orientation dependent properties of anisotropic materials are included in the adjoint method, which provides a more precise prediction of light propagation within such materials. The proposed method is used to design ultra-compact wavelength division demultiplexers in the X-cut thin-film lithium niobate (TFLN) platform. By benchmarking the device performances of our method with those of classical scalar-based inverse design, we demonstrate that this method properly addresses the critical issue of material anisotropy in the X-cut TFLN platform. This proposed method fills the gap of inverse design of anisotropic materials based photonic devices, which finds prominent applications in TFLN platforms and other anisotropic-material based photonic integration platforms

A multimechanistic antibody targeting receptor-binding sites potently cross-protects against influenza B viruses

流感病毒HA是研制流感药物和流感疫苗的重要靶标，但HA具有高度变异性，如何在高变异HA中找到不变之处，即高度保守表位，是研制流感特效药物和广谱疫苗的关键。近年来国外报道的流感HA广谱中和单抗的识别位点均在较为保守的HA茎部区，而针对流感病毒与细胞受体结合部位的HA头部区尤其是RBS区，一直未能发现广谱中和抗体。夏宁邵教授团队通过探索多种免疫策略和筛选策略，成功筛选出一株广谱中和单抗12G6，识别一个位于HA头部RBS上的全新保守性表位。体外实验显示12G6人源化改造的C12G6抗体能高效中和1940-2016年间世界各地历年流行的代表三个遗传变异亚系的18个乙型流感病毒代表株对细胞的感染，并能保护小鼠致死性感染，治疗效果显著优于已报道的代表性抗体以及抗流感药物；C12G6与“达菲”联合用药具有明显的协同效果。此外，雪貂感染模型的预防和治疗效果进一步证实了C12G6作为抗体药物的治疗潜能。研究还显示该表位是病毒感染复制的关键表位，该位点的突变会造成病毒毒力显著下降。最后，研究揭示了C12G6通过五种不同的抗病毒作用机制发挥作用，提示其高效的抗病毒活性得益于多机制协同效应，这也是目前国内外第一次发现一个流感抗体能通过如此全面的抗病毒机制发挥作用。 该发现为研制能抵抗各种变异株的乙型流感特效治疗药物和通用疫苗带来新希望。 该研究工作依托分子疫苗学和分子诊断学国家重点实验室（厦门大学）、国家传染病诊断试剂与疫苗工程技术研究中心、厦门大学养生堂生物药物联合实验室完成。陈毅歆副教授、夏宁邵教授为该研究论文的共同通讯作者。在读博士研究生沈晨光、陈俊煜、李睿、王国松和硕士研究生张梦娅等为共同第一作者。【Abstract】Influenza B virus causes considerable disease burden worldwide annually, highlighting the limitations of current influenza vaccines and antiviral drugs. In recent years, broadly neutralizing antibodies (bnAbs) against hemagglutinin (HA) have emerged as a new approach for combating influenza. We describe the generation and characterization of a chimeric monoclonal antibody, C12G6, that cross-neutralizes representative viruses spanning the 76 years of influenza B antigenic evolution since 1940, including viruses belonging to the Yamagata, Victoria, and earlier lineages. Notably, C12G6 exhibits broad cross-lineage hemagglutination inhibition activity against influenza B viruses and has higher potency and breadth of neutralization when compared to four previously reported influenza B bnAbs. In vivo, C12G6 confers stronger cross-protection against Yamagata and Victoria lineages of influenza B viruses in mice and ferrets than other bnAbs or the anti-influenza drug oseltamivir and has an additive antiviral effect when administered in combination with oseltamivir. Epitope mapping indicated that C12G6 targets a conserved epitope that overlaps with the receptor binding site in the HA region of influenza B virus, indicating why it neutralizes virus so potently. Mechanistic analyses revealed that C12G6 inhibits influenza B viruses via multiple mechanisms, including preventing viral entry, egress, and HA-mediated membrane fusion and triggering antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity responses. C12G6 is therefore a promising candidate for the development of prophylactics or therapeutics against influenza B infection and may inform the design of a truly universal influenza vaccine.This research was supported by grants from the National Natural Science Foundation of China (31670934 and 81371817), the Ministry of Science and Technology of the People’s Republic of China (2011ZX09102-009-12 and 2012DFH30020), the Research Grants Council of the Hong Kong Special Administrative Region (7629/13M, 17103214, and 17154516), and a sponsored research agreement from Sanofi Pasteur. 研究工作得到了香港大学新发传染病国家重点实验室和赛诺菲巴斯德公司的技术支持和帮助，获得国家自然科学基金、新药创制国家科技重大专项、科技部对港科技合作项目等课题资助