The Experts below are selected from a list of 35388 Experts worldwide ranked by ideXlab platform
S. Aramvith - One of the best experts on this subject based on the ideXlab platform.
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wireless video transport using conditional Retransmission and low delay interleaving
IEEE Transactions on Circuits and Systems for Video Technology, 2002Co-Authors: S. AramvithAbstract:We consider the scenario of using Automatic Repeat reQuest (ARQ) Retransmission for two-way low-bit-rate video communications over wireless Rayleigh fading channels. Low-delay constraint may require that a corrupted retransmitted packet not be retransmitted again, and thus there will be packet errors at the decoder which results in video quality degradation. We propose a scheme to improve the video quality. First, we propose a low-delay interleaving scheme that uses the video encoder buffer as a part of interleaving memory. Second, we propose a conditional Retransmission strategy that reduces the number of Retransmissions. Simulation results show that our proposed scheme can effectively reduce the number of packet errors and improve the channel utilization. As a result, we reduce the number of skipped frames and obtain a peak signal-to-noise ratio improvement up to about 4 dB compared to H.263 TMN-8.
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Wireless video transport using conditional Retransmission and low-delay interleaving
ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196), 2001Co-Authors: S. AramvithAbstract:We consider the scenario of using Automatic Repeat reQuest (ARQ) Retransmission for two-way low-bit-rate video communications over wireless Rayleigh fading channels. A low-delay constraint may require that a corrupted retransmitted packet not be retransmitted again, thus there will be packet-errors at the decoder which results in video quality degradation. In this paper. We propose a scheme to improve the video quality. First, we propose a low-delay interleaving scheme that combines the interleaving memory with the video encoder buffer. Second, we propose a conditional Retransmission strategy that reduces the number of Retransmissions. Simulation results show that our proposed scheme can effectively reduce the number of packet errors and improve the channel utilization. As a result, we obtain PSNR (Peak Signal to Noise Ratio) improvement up to about 4 dB compared to H.263 TMN8.
Preben Mogensen - One of the best experts on this subject based on the ideXlab platform.
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a blind Retransmission scheme for ultra reliable and low latency communications
Vehicular Technology Conference, 2018Co-Authors: Renato Abreu, Thomas Jacobsen, Gilberto Berardinelli, Klaus I Pedersen, Preben MogensenAbstract:This work is related to 5G new radio concept design, with focus on ultra-reliable and low latency communication (URLLC) use cases. We mainly target to achieve the stringent latency and reliability requirements for transmissions over the air interface, such as 99.999% success probability within 1 ms. Meeting these requirements in an efficient way, that is, without draining the network capacity is one of the main challenges for the new radio standardization. In this work, we propose a scheme to perform blind Retransmissions on shared radio resources together with the application of successive interference cancellation to receive remaining non-decoded data with low delay penalty. The method avoids control errors and extra delays existent on feedback-based Retransmission schemes. The investigations also show that blind Retransmission on shared resources is more resource efficient than a conservative single shot transmission, depending on the number of users sharing the resources.
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performance of fast node b scheduling and l1 harq schemes in wcdma uplink packet access
Vehicular Technology Conference, 2004Co-Authors: Claudio Rosa, J Outes, K Dimou, Troels B Sorensen, Jeroen Wigard, F Frederiksen, Preben MogensenAbstract:The performance of WCDMA uplink systems deploying Node B based scheduling and fast hybrid ARQ (HARQ) Retransmission protocols is studied. With fast Node B scheduling and fast L1 HARQ schemes, both the uplink packet scheduling functionality and the entity controlling the Retransmission mechanism are moved from the radio network controller (RNC) to the Node B. A Node B scheduling algorithm is proposed to increase the utilisation of the allocated uplink resources; this is achieved by making use of already existing information about the transmitted data rate of the UEs. Moreover, fast L1 HARQ schemes make Retransmissions less costly from a delay perspective compared to an equivalent RNC controlled ARQ mechanism. Therefore, the physical channel can be operated with somewhat higher error probability, which converts directly into enhanced system capacity. The potential capacity gain from fast L1 Node B controlled HARQ strategies and fast Node B scheduling operation is estimated by means of an analytical study, as well as system level simulations. The combined gain obtained by jointly deploying fast Node B scheduling and fast L1 HARQ Retransmission schemes is estimated in the range from 25% to 60%, depending on the mobility scenario. Fast Node B scheduling and L1-based HARQ protocols are included in 3GPP's "Feasibility Study for Enhanced Uplink for UTRA FDD" (TR 25.896 V1.1.2, 2003).
M O Damen - One of the best experts on this subject based on the ideXlab platform.
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the mimo arq channel diversity multiplexing delay tradeoff
IEEE Transactions on Information Theory, 2006Co-Authors: Hesham El Gamal, Giuseppe Caire, M O DamenAbstract:In this paper, the fundamental performance tradeoff of the delay-limited multiple-input multiple-output (MIMO) automatic Retransmission request (ARQ) channel is explored. In particular, we extend the diversity-multiplexing tradeoff investigated by Zheng and Tse in standard delay-limited MIMO channels with coherent detection to the ARQ scenario. We establish the three-dimensional tradeoff between reliability (i.e., diversity), throughput (i.e., multiplexing gain), and delay (i.e., maximum number of Retransmissions). This tradeoff quantifies the ARQ diversity gain obtained by leveraging the Retransmission delay to enhance the reliability for a given multiplexing gain. Interestingly, ARQ diversity appears even in long-term static channels where all the Retransmissions take place in the same channel state. Furthermore, by relaxing the input power constraint allowing variable power levels in different Retransmissions, we show that power control can be used to dramatically increase the diversity advantage. Our analysis reveals some important insights on the benefits of ARQ in slow-fading MIMO channels. In particular, we show that 1) allowing for a sufficiently large Retransmission delay results in an almost flat diversity-multiplexing tradeoff, and hence, renders operating at high multiplexing gain more advantageous; 2) MIMO ARQ channels quickly approach the ergodic limit when power control is employed. Finally, we complement our information-theoretic analysis with an incremental redundancy lattice space-time (IR-LAST) coding scheme which is shown, through a random coding argument, to achieve the optimal tradeoff(s). An integral component of the optimal IR-LAST coding scheme is a list decoder, based on the minimum mean-square error (MMSE) lattice decoding principle, for joint error detection and correction. Throughout the paper, our theoretical claims are validated by numerical results
Wei Ni - One of the best experts on this subject based on the ideXlab platform.
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A New Trellis Model for MAC Layer Cooperative Retransmission Protocols
IEEE Transactions on Vehicular Technology, 2017Co-Authors: Wei Ni, Brett Hagelstein, Mehran Abolhasan, Xin WangAbstract:Comparison studies on timer-based distributed cooperative Retransmission protocols are challenging, given a variety of backoff techniques. We propose a new unified model, which can characterize a wide range of cooperative Retransmission protocols. The key idea is a new trellis diagram that extrapolates the Retransmission probabilities in each timeslot to the entire cooperative process. Following the trellis, performance metrics, such as success rate and collision intensity, can be derived in a structured manner. The new trellis model, coupled with Markov techniques, can be also extended to analyze the distributed binary exponential backoff processes of cooperative Retransmissions. Confirmed by simulations, the proposed trellis model accurately reveals the impact of the relays' relative locations and density on different protocols. Our model also has the potential to be used as a management tool to adaptively configure protocol parameters.
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Analytic Performance Model for State-Based MAC Layer Cooperative Retransmission Protocols
IEEE Transactions on Mobile Computing, 2016Co-Authors: Brett Hagelstein, Mehran Abolhasan, Daniel Franklin, Farzad Safaei, Wei NiAbstract:Cooperative Retransmission can significantly improve link reliability over lossy and time-varying wireless links. However, comparing Retransmission protocols is challenging, and generally requires simplistic assumptions specific to each protocol. In this paper, we develop a general model to evaluate cooperative Retransmission protocols with distributed, slot-based contention algorithms. Specifically, we propose to calculate the relay time-out probabilities at a MAC time-slot scale, formulate Retransmission outcomes as functions of the time-out probabilities, and derive the probability of a Retransmission process for every data frame. We also propose a Markov extension of our model to characterise the dependency between Retransmissions of multiple frames. This enables our model to analyse continuous Retransmissions of successive frames. Validated by QualNet simulations, our model can analytically predict the probabilities of cooperative Retransmissions with an accuracy of ±1%. As a result, direct comparisons between cooperative Retransmission protocols become tangible, without implementing the full protocol in a state-based simulator.
Renato Abreu - One of the best experts on this subject based on the ideXlab platform.
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a blind Retransmission scheme for ultra reliable and low latency communications
Vehicular Technology Conference, 2018Co-Authors: Renato Abreu, Thomas Jacobsen, Gilberto Berardinelli, Klaus I Pedersen, Preben MogensenAbstract:This work is related to 5G new radio concept design, with focus on ultra-reliable and low latency communication (URLLC) use cases. We mainly target to achieve the stringent latency and reliability requirements for transmissions over the air interface, such as 99.999% success probability within 1 ms. Meeting these requirements in an efficient way, that is, without draining the network capacity is one of the main challenges for the new radio standardization. In this work, we propose a scheme to perform blind Retransmissions on shared radio resources together with the application of successive interference cancellation to receive remaining non-decoded data with low delay penalty. The method avoids control errors and extra delays existent on feedback-based Retransmission schemes. The investigations also show that blind Retransmission on shared resources is more resource efficient than a conservative single shot transmission, depending on the number of users sharing the resources.
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Reliability Analysis of Uplink Grant-Free Transmission Over Shared Resources
IEEE Access, 2018Co-Authors: Gilberto Berardinelli, Nurul Huda Mahmood, Renato Abreu, Klaus Pedersen, Thomas Jacobsen, Istvan Z. Kovacs, Preben Elgaard MogensenAbstract:Uplink grant-free schemes have the promise of reducing the latency of a user-equipment-initiated transmission by avoiding the handshaking procedure for acquiring a dedicated scheduling grant. However, the possibility of successfully delivering a payload within a latency constraint may be severely compromised in case of grant-free operations over shared radio resources. In this paper, we study the performance of two different uplink grant-free schemes over shared resources recently discussed within the fifth generation new radio standardization, namely, a solution based on a stop-and-wait (SAW) protocol and a blind Retransmission approach. Performance is evaluated assuming Rayleigh fading channels with a maximum ratio combining (MRC) multi-antenna receiver. Analytical results show the benefits of grant-free transmission with respect to the traditional grant-based approach for a tight latency constraint. A high-order receive diversity is beneficial to leverage the MRC gain and enables the possibility of achieving the 10−5 outage probability target set for ultra-reliable low-latency communication services. The blind Retransmission approach is significantly penalized by identification and signaling errors, while a SAW solution with potentially scheduled Retransmissions out of the shared bandwidth leads to the lowest outage probability, at least for frequent packet arrivals.
