最新刊期
      2023 年 第 2 期
      • 2023, 1(2) DOI: 10.1016/S2949-7159(23)00028-8
          
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        发布时间：2023-09-19
      • Zuobin Ying,Laican Song,Deng Chen,Wusong Lan,Ximeng Liu
        2023, 1(2) DOI: 10.1016/j.jiixd.2023.01.001
        摘要：The sharding technique enables blockchain to process transactions in parallel by dividing blockchain nodes into small groups, each of which handles a subset of all transactions. One of the issues with blockchain sharding is generating a large number of cross-shard transactions that need to be checked on the output shard as well as the destination shard. Our analysis suggests that the processing efficiency of cross-shard transactions is consistent with the barrel effect, i.e., that efficiency is more dependent on slower processing shard. Most of the existing studies focus on how to deal with cross-shard transactions, but neglecting the fact that the relative independence between sharding results in different incentive costs between sharding. We perform a sharding analysis on 100,000 real transactions data on Ethereum, and the results show that there is a large difference in gas prices between different shards indeed. In this paper, we propose an Adaptive Weight Incentive (AWI) for Blockchain Sharding, which uses adaptive weight in place of traditional incentive, to address the problem of differing incentive costs for each shard. Take Ethereum as an example, AWI-BS computes the weight of a transaction as a function of a combination of the underlying gas price, the latency of the transaction, and the urgency of the transaction. Then the node chooses which transaction to pack based on the AWI-BS. Lastly, we also perform an in-depth analysis of AWI-BS's security and effectiveness. The evaluation indicates that AWI-BS outperforms the other alternatives in terms of transaction confirmation latency, transaction hit rate, and system throughput.  
        关键词：Sharding;Blockchain;Incentive mechanism   
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        发布时间：2023-09-19
      • Wei Liu,Zhiqiang Dun
        2023, 1(2) DOI: 10.1016/j.jiixd.2023.04.002
        摘要：Deep learning based channel state information (CSI) fingerprint indoor localization schemes need to collect massive labeled data samples for training, and the parameters of the deep neural network are used as the fingerprints. However, the indoor environment may change, and the previously constructed fingerprint may not be valid for the changed environment. In order to adapt to the changed environment, it requires to recollect massive amount of labeled data samples and perform the training again, which is labor-intensive and time-consuming. In order to overcome this drawback, in this paper, we propose one novel domain adversarial neural network (DANN) based CSI Fingerprint Indoor Localization (D-Fi) scheme, which only needs the unlabeled data samples from the changed environment to update the fingerprint to adapt to the changed environment. Specifically, the previous environment and changed environment are treated as the source domain and the target domain, respectively. The DANN consists of the classification path and the domain-adversarial path, which share the same feature extractor. In the offline phase, the labeled CSI samples are collected as source domain samples to train the neural network of the classification path, while in the online phase, for the changed environment, only the unlabeled CSI samples are collected as target domain samples to train the neural network of the domain-adversarial path to update parameters of the feature extractor. In this case, the feature extractor extracts the common features from both the source domain samples corresponding to the previous environment and the target domain samples corresponding to the changed environment. Experiment results show that for the changed localization environment, the proposed D-Fi scheme significantly outperforms the existing convolutional neural network (CNN) based scheme.  
        关键词：Indoor localization;Domain adversarial neural network;CSI;Fingerprint;Deep learning   
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        发布时间：2023-09-19
      • Qianfan Wang,Kongjing Guo,Xiao Ma
        2023, 1(2) DOI: 10.1016/j.jiixd.2023.05.001
        摘要：In this paper, based on the block Markov superposition transmission (BMST) technique, we present a new class of coupled low-density parity-check (LDPC) codes for the transport block (TB)-based transmission to improve the error-correcting performance. For encoding, the previous LDPC codewords corresponding to a TB (at prior time slot) are interleaved and superimposed onto the current LDPC codewords, resulting in the transmitted codewords. For decoding, the sliding window decoding algorithm with sum-product or min-sum implementations can be employed, inheriting a relatively low-latency decoding. A distinguished advantage of the proposed coded transmission over spatially coupled LDPC (SC-LDPC) codes is that the encoder/decoder of the proposed codes can be designed by reusing the encoder/decoder architecture of component block LDPC codes. To analyze the waterfall performance of BMST-LDPC code ensembles, we present the protograph-based EXIT chart analysis, which can efficiently predict the error-correcting performance in waterfall region. To analyze the error-floor performance of BMST-LDPC codes, we employ the genie-aided (GA) lower bound, which can efficiently predict the error-correcting performance in error-floor region. For ease of implementation, the BMST-LDPC codes are constructed by taking the (2, 4)-raptor-like LDPC codes or the 5G LDPC codes as the basic components. The numerical results reveal that the proposed codes can have capacity-approaching performance, exhibiting a gap of 0.007 ​dB away from the corresponding Shannon limit. They also reveal that, by using the proposed BMST construction, the error-correcting performance of the original 5G block LDPC codes can be significantly improved, achieving coding gains up to one dB over the AWGN channels and two dB over the fast fading channels.  
        关键词：5G NR;Block Markov superposition transmission (BMST);Low-density parity-check (LDPC) codes;Spatially-coupled LDPC (SC-LDPC) codes   
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        发布时间：2023-09-19
      • Yue Li,Shuai Guo,Qipeng Song,Yao Wang,Xiaomin Wei,Jianfeng Ma
        2023, 1(2) DOI: 10.1016/j.jiixd.2023.04.003
        摘要：Locator/identifier separation paradigm (LISP) is an emerging Internet architecture evolution trend that decouples the identifier and location of an entity attached to the Internet. Due to its flexibility, LISP has seen its application in various fields such as mobile edge computing, and V2X networks. However, LISP relies on a DNS-like mapping system to associate identifiers and locations before connection establishment. Such a procedure incurs an extra latency overhead and thus hinders the adoption of LISP in delay-sensitive use cases. In this paper, we propose a novel RNN-based mapping prediction scheme to boost the performance of the LISP mapping resolution, by modeling the mapping procedure as a time series prediction problem. The key idea is to predict the mapping data regarding services to be utilized by users in edge networks administered by xTRs and proactively cache the mapping information within xTRs in advance. We compare our approach with several baseline methods, and the experiment results show a 30.02% performance gain in LISP cache hit ratio and 55.6% delay reduction compared with the case without mapping prediction scheme. This work preliminarily proves the potential of the approach in promoting low-latency LISP-based use cases.  
        关键词：LISP;Future internet architecture;Mapping prediction;Recurrent neural network   
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        发布时间：2023-09-19
      • Fangyuan Liao,Yuhan Ruan,Hangyu Zhang,Rui Zhang,Tao Li,Yongzhao Li
        2023, 1(2) DOI: 10.1016/j.jiixd.2023.04.001
        摘要：In view of the difficulty of obtaining downlink channel state information, partial reciprocity based channel covariance matrix (CCM) reconstruction has attracted a lot of attention in frequency division duplex (FDD) multi-antenna systems. Taking both the impact of CCM reconstruction on system performance and design complexity, we investigate an adaptive CCM reconstruction in this paper. Specifically, to effectively evaluate the validity of the reciprocity, we firstly analyze the characteristics of the partial reciprocity and define a reciprocity evaluation criterion. Then, we propose a partial antenna based angular power spectrum (APS) estimating algorithm to further reduce the complexity of the CCM reconstruction. Finally, simulation results demonstrate the superiority of our proposed schemes.  
        关键词：Frequency division duplex;Partial reciprocity;Channel covariance matrix reconstruction;Reciprocity evaluation criterion;Angular power spectrum   
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        发布时间：2023-09-19
      • Hongbiao Liu,Mengfei Yang,Tingyu Wang,Chenghao Song,Shenghui Zhu,Xi Chen
        2023, 1(2) DOI: 10.1016/j.jiixd.2023.03.002
        摘要：Multi-core processor is widely used as the running platform for safety-critical real-time systems such as spacecraft, and various types of real-time tasks are dynamically added at runtime. In order to improve the utilization of multi-core processors and ensure the real-time performance of the system, it is necessary to adopt a reasonable real-time task allocation method, but the existing methods are only for single-core processors or the performance is too low to be applicable. Aiming at the task allocation problem when mixed real-time tasks are dynamically added, we propose a heuristic mixed real-time task allocation algorithm of virtual utilization VU-WF (Virtual Utilization Worst Fit) in multi-core processor. First, a 4-tuple task model is established to describe the fixed-point task and the sporadic task in a unified manner. Then, a VDS (Virtual Deferral Server) for serving execution requests of fixed-point task is constructed and a schedulability test of the mixed task set is derived. Finally, combined with the analysis of VDS's capacity, VU-WF is proposed, which selects cores in ascending order of virtual utilization for the schedulability test. Experiments show that the overall performance of VU-WF is better than available algorithms, not only has a good schedulable ratio and load balancing but also has the lowest runtime overhead. In a 4-core processor, compared with available algorithms of the same schedulability ratio, the load balancing is improved by 73.9%, and the runtime overhead is reduced by 38.3%. In addition, we also develop a visual multi-core mixed task scheduling simulator RT-MCSS (open source) to facilitate the design and verification of multi-core scheduling for users. As the high performance, VU-WF can be widely used in resource-constrained and safety-critical real-time systems, such as spacecraft, self-driving cars, industrial robots, etc.  
        关键词：Mixed real-time task set;Multi-core scheduling;Task dynamical adding;Virtual utilization;Scheduling simulator   
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        发布时间：2023-09-19
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