共查询到20条相似文献,搜索用时 812 毫秒
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A MAC/PHY cross-layer design for efficient ARQ protocols 总被引:1,自引:0,他引:1
《Communications Letters, IEEE》2008,12(12):909-911
In many wireless data systems, automatic repeat request (ARQ) and hybrid automatic repeat request (HARQ) work independently. In this paper, we introduce a new ARQ feedback scheme called Cross-Layer ARQ (CL-ARQ), where ARQ closely interoperates with HARQ by making use of the acknowledgement of HARQ internally. By doing so, CL-ARQ not only removes the overhead for ARQ acknowledgement messages, but also improves the average delivery delay and TCP throughput. Especially, when the entities in charge of HARQ and ARQ are located far apart geographically, CL-ARQ remarkably outperforms the legacy scheme. 相似文献
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LIU Fang KONG Jian WANG Wen-bo LIU Yuan-an Beijing University of Posts Telecommunications Beijing P.R.China 《中国邮电高校学报(英文版)》2004,11(4)
In this paper,four schemes of Hybrid Automatic-Repeat-Request(HARQ)for Orthogonal Frequency DivisionMultiplexing(OFDM)systems are evaluated when they are used in different channel environments.The AccumulativeCorrect Packet Reception Rate(ACPRR)performance of four HARQ schemes is compared in order to verify which ARQschemes are more suitable for different mobility OFDM systems.Computer simulation results show that the maximal ratiocombining frequency diversity ARQ scheme and type Ⅲ HARQ with frequency diversity is more suitable for low mobilityOFDM system.However the type Ⅲ HARQ without frequency diversity is more suitable for high mobility OFDM systembecause of the remarkable time diversity which reduces the required retransmission number to about 2 at the ACPRR of0.96. 相似文献
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Qian Huang Q. Chan S. Ping L. Zukerman M. 《Wireless Communications, IEEE Transactions on》2007,6(7):2476-2485
A novel hybrid ARQ (HARQ) scheme using a concatenated two-state trellis-coded modulation (CT-TCM) code is proposed for improving wireless TCP throughput. A distinguished feature of the proposed scheme is that the heavily punctured TCM codes are used for retransmissions of the corrupted data block, which are combined at the receiver with the previously received sequences of the same data block for decoding. By this method, significantly improved coding gain and efficient spectrum utilization can be achieved with very low complexity. A Markov model is developed to evaluate TCP throughput over the proposed HARQ in wireless link. By both analysis and simulation, we demonstrate that compared with other existing TCM-based ARQ schemes, significant improvement of TCP throughput over wireless links is achieved by the proposed CT-TCM HARQ while smaller buffer size is required at the access point. 相似文献
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In this paper, we introduce a new hybrid ARQ technique for broadcasting or multicasting in erasure channel. The system is tested according to the objective criteria—quantity of information sent by the source, loses, and number of negative acknowledgments (NACKs) sent by the receiver nodes (end nodes). We compare our proposed method with automatic repeat request (ARQ), hybrid ARQ II (HARQ II), and also with a forward error correction (FEC) transmission technique based on Reed Solomon code (RS). The main focus of the presented HARQ is to reduce the quantity of redundant information sent by the source as well as the number of NACKs sent by the receivers, maintaining the condition that all the information is being recovered successfully by the receivers. 相似文献
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Tae Chul Hong Kun‐Seok Kang Bon‐Jun Ku Do‐Soeb Ahn 《International Journal of Satellite Communications and Networking》2014,32(5):377-392
Hybrid automatic repeat request (HARQ) and automatic repeat request (ARQ) of the terrestrial long‐term evolution (LTE) system are designed considering the very short propagation delay of terrestrial environment. Therefore, when HARQ and ARQ are applied to the LTE‐based mobile satellite communication system, the inefficiency is caused by the long propagation delay of satellite environment. This paper proposes the interaction method between HARQ and ARQ for the decrease of inefficiency in the LTE‐based mobile satellite communication system. The existing concept of layered architecture about HARQ and ARQ is also maintained in our interaction method. Simulation results reveal that our proposed scheme can provide the larger spectrum efficiency than that of the non‐interaction scheme in all environments. The performance improvement can be up to 2.04 times through the interaction method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Visotsky E. Yakun Sun Tripathi V. Honig M.L. Peterson R. 《Communications, IEEE Transactions on》2005,53(6):987-997
Incremental redundancy, or Hybrid type-II ARQ (HARQ), algorithms use a combination of forward error correction and retransmissions to guarantee reliable packet data communications. In this work, we propose a HARQ algorithm that exploits received packet reliability to improve system performance. Specifically, the receiver uses the average magnitude of the log-likelihood ratios of the information bits as the packet reliability metric, which is then used to determine the sizes of subsequent retransmissions. The proposed retransmission strategy attempts to maximize user throughput while satisfying a maximum packet delay constraint. The performance of our reliability-based HARQ algorithm is evaluated in static and time-varying channels through simulations. Furthermore, analytical results on the relationship between the reliability metric, the code rate and the block error rate are presented. 相似文献
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The 3GPP working group proposes the Long‐Term Evolution (LTE) system as the 4G mobile communications technology. To reduce the transmission latency in the radio access network, Evolved Universal Terrestrial Radio Access Network (E‐UTRAN), of LTE, the base station and radio network controller are merged into a single network node, namely eNB. In E‐UTRAN, the Stop‐And‐Wait Hybrid ARQ (SAW‐HARQ) protocol in the Media Access Control (MAC) layer deals with transmission errors without the need to engage the ARQ protocol in the Radio Link Control (RLC) layer. The HARQ and ARQ protocols interact only in case of dealing HARQ residual errors. In this paper, we propose an analytical model to model the behavior of the HARQ–ARQ Interaction. Our analytical model is validated against the simulation experiments that provide more performance metrics (which cannot be obtained through our analytical model). Finally, we investigate the impacts of the HARQ–ARQ Interaction on the Protocol Data Unit (PDU) transmission delay based on our simulation experiments. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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下一代移动通信系统在高速移动的条件下,需要更高的吞吐量和更大的带宽。这就需要采用更好的信道编码(turbo码等)、HARQ策略和信道均衡技术。但是,turbo译码是一个复杂的过程,在进行信号处理时会耗费用户大量的时间和功率。因此与turbo译码相关的HARQ策略会对系统性能产生很大影响。提出了一种CQI辅助的HARQ策略。这种策略主要利用了已经测量得到的CQI来跳过HARQ在首次传输和重传过程中不必要的解调和译码过程。通过采用HARQ策略,当误帧率高于门限时可以节省UE端大约55%的功率。 相似文献
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无线Mesh网技术是一种新的无线网络技术,其核心是任何无线设备节点都可以同时作为接入点(AP)和路由器,网络中的每个节点都可以发送和接收信号,每个节点都可以与一个或者多个对等节点进行直接通信。无线Mesh网中需要考虑完成通信的多跳过程中产生的数据传输可靠性的保障问题。使用第三代合作伙伴计划(3GPP)的系统架构中提出的混合自动重传请求(HARQ)和自动重传请求(ARQ)功能,可以对多跳链路数据可靠传输进行保障。其中针对HARQ提出了逐跳和端到端两种方法,而对于ARQ功能除了逐跳和端到端两种方法外还增加了最后一跳的保障机制。从协议栈构架设计的角度,根据HARQ和OARQ机制提出了3种解决方法:分层机制、Relay ARQ机制、多剧SARQ机制。 相似文献
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《Vehicular Technology, IEEE Transactions on》2009,58(6):2769-2782
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It has been known that adaptive modulation and coding (AMC) at the physical layer can be combined with a truncated automatic
repeat request (ARQ) at the data link layer so as to maximize the spectral efficiency under prescribed delay and error performance
constraint. In this paper, we consider the same joint design approach when incremental redundancy-based hybrid ARQ (IR-HARQ)
is associated with an AMC design at the physical layer. The extensive simulation studies for predicting the progressive combining
gain with each retransmission enables to evaluate the bandwidth efficiency that can be achieved by selecting a more aggressive
modulation and coding rate set (MCS) at the expense of packet error rate in earlier transmissions. It has been demonstrated
that the aggressive AMC design approach in association with IR-based truncated HARQ can improve bandwidth efficiency by 5.8
and 3.3 dB, as compared to the conservative AMC design approach with truncated HARQ and aggressive AMC design approach with
truncated ARQ (i.e., without taking the progressive combining gain in HARQ into account), respectively. 相似文献
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Lijun Zhang Victor O. K. Li Zhigang Cao 《International Journal of Communication Systems》2005,18(2):97-117
Non‐binary type‐II hybrid ARQ (HARQ), which combines shortened Reed–Solomon (RS) code with ARQ, is proposed. Its throughput is obtained by extending Lin and Yu's analysis of binary type‐II HARQ. The reliability and average delay are also obtained. The analytical results show that non‐binary HARQ outperforms its binary counterpart in throughput, reliability and average delay when proper RS codes are selected. Non‐binary HARQs are applied adaptively in a cellular phone system with uniformly distributed mobile terminals (MTs). MTs switch adaptively between two different hybrid schemes according to the average SNR of the received signals. The adaptive parameters include the size of the modulation constellation, the error‐correction coding and their joint adaptation. Numerical results show that the adaptive scheme always outperforms its non‐adaptive counterparts, and the adaptive modulation scheme is superior to adaptive coding and the joint adaptation scheme when the implementation complexity is a limiting factor. Robustness analysis shows that introducing a mixed modulation scheme in addition to QPSK and 8PSK in the adaptive modulation scheme is unnecessary, and HARQ with adaptive modulation is insensitive to deviations from the optimal threshold, thus facilitating its implementation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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为了使无线通信系统中数据的传输快速可靠,需要采用自动重发请求(ARQ)和前向纠错码(FEC)相结合的混合自动重发请求(HARQ)技术。针对星座映射中比特符号产生可靠性差异,提出一种自适应星座重组的新型HARQ方案。仿真结果表明,该新型HARQ方案具有降低系统误码率和时延,提高系统性能的优点。 相似文献
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Song Fei Tong Xiaobing Wu Qihui Wang Jinlong 《电子科学学刊(英文版)》2008,25(1):53-58
A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR). 相似文献