The Experts below are selected from a list of 36303 Experts worldwide ranked by ideXlab platform
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, Jeroen Wigard, F Frederiksen, Konstantinos Dimou, Troels B Sorensen, 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).
James Gross - One of the best experts on this subject based on the ideXlab platform.
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channel coding versus cooperative arq reducing outage probability in ultra low latency wireless communications
Global Communications Conference, 2015Co-Authors: Martin Serror, Christian Dombrowski, Klaus Wehrle, James GrossAbstract:Nowadays wireless communications still lack the ability to provide high reliability and low latency, although mission-critical applications, such as found in industrial automation, rely on both requirements. The main challenge is that an improved reliability often comes at the price of an increased latency. It has been shown that cooperative schemes can effectively increase the reliability by leveraging spatial diversity. However, an important question remains how to integrate cooperative schemes when dealing with very short latency bounds and especially how much time should be reserved for potential Retransmissions. In this work, we propose and evaluate a centralized communication system that uses cooperative ARQ to achieve high reliability under the constraint of a strict latency bound of 1 ms. We evaluate this system analytically, using an outage-capacity model with average channel state information, by varying the reserved time for Retransmissions, where a shorter time for Retransmissions allows to apply stronger channel codes in the original transmission. As a baseline, we use a system without cooperation mechanism, thus applying the given time for stronger channel codes in the direct transmission of a message. In case of cooperation, a third station may act as a relay if the original transmission failed. Our results reveal that an optimal size of the reserved retransmission time exists around 15% to 30% of the total frame time, increasing the reliability by several orders of magnitude, even for a large number of transmissions within a communication cycle.
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GLOBECOM Workshops - Channel Coding versus Cooperative ARQ: Reducing Outage Probability in Ultra-Low Latency Wireless Communications
2015 IEEE Globecom Workshops (GC Wkshps), 2015Co-Authors: Martin Serror, Christian Dombrowski, Klaus Wehrle, James GrossAbstract:Nowadays wireless communications still lack the ability to provide high reliability and low latency, although mission-critical applications, such as found in industrial automation, rely on both requirements. The main challenge is that an improved reliability often comes at the price of an increased latency. It has been shown that cooperative schemes can effectively increase the reliability by leveraging spatial diversity. However, an important question remains how to integrate cooperative schemes when dealing with very short latency bounds and especially how much time should be reserved for potential Retransmissions. In this work, we propose and evaluate a centralized communication system that uses cooperative ARQ to achieve high reliability under the constraint of a strict latency bound of 1 ms. We evaluate this system analytically, using an outage-capacity model with average channel state information, by varying the reserved time for Retransmissions, where a shorter time for Retransmissions allows to apply stronger channel codes in the original transmission. As a baseline, we use a system without cooperation mechanism, thus applying the given time for stronger channel codes in the direct transmission of a message. In case of cooperation, a third station may act as a relay if the original transmission failed. Our results reveal that an optimal size of the reserved retransmission time exists around 15% to 30% of the total frame time, increasing the reliability by several orders of magnitude, even for a large number of transmissions within a communication cycle.
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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joint source channel coding using simplified block based segmentation and content based rate control for wireless video transport
International Conference on Information Technology: Coding and Computing, 2002Co-Authors: S. Aramvith, H Kortrakulkij, D Tancharoen, S JitapankulAbstract:The scenario of using Automatic Repeat reQuest (ARQ) retransmission for two-way low bit-rate video communications over wireless Rayleigh fading channels is studied. In this kind of channel, the packets inevitably experience errors during deep fades. The Retransmissions can be used to re-send such packets. During Retransmissions, the video encoder buffer fills up quickly and may cause the rate-control algorithm to skip frames or allocate less number of bits to encode the video frame. To reduce the number of frames skipped and improve bit allocation, we propose a content-based rate-control scheme using simplified block-based segmentation to intelligently allocate more bits to the foreground region. In addition, our proposed scheme also takes into consideration the effects of the video buffer fill-up, an a priori channel model, channel feedback information. The simulation results indicate that our proposed scheme encodes the video sequences with higher quality on the foreground region and much fewer frame skipping as compared to H.263 TMN8.
Xavier Lagrange - One of the best experts on this subject based on the ideXlab platform.
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Opportunistic relays in 802.11 networks
IEEE Vehicular Technology Conference, 2014Co-Authors: Lucien Loiseau, Nicolas Montavont, Xavier LagrangeAbstract:We propose a new lightweight mechanism called Forwarding By Retransmission, that allows 802.11 stations to opportunistically relay overheard frames toward a destination. When a destination does not receive a frame, any other receiver that has better radio conditions than the source of the frame could participate in the retransmission process along with the source. This reduces the number of Retransmissions made by stations with poor connectivity. We show by NS-2 simulations that our mechanism allows to fairly share the bandwidth among stations, even for those with poor radio quality and high packet error rates. Our solution comes with only a few modifications to the frame structure and a change in the acknowledgement semantic.
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VTC Fall - Opportunistic Relays in 802.11 Networks
2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall), 2014Co-Authors: Lucien Loiseau, Nicolas Montavont, Xavier LagrangeAbstract:We propose a new lightweight mechanism called Forwarding By Retransmission, that allows 802.11 stations to opportunistically relay overheard frames toward a destination. When a destination does not receive a frame, any other receiver that has better radio conditions than the source of the frame could participate in the retransmission process along with the source. This reduces the number of Retransmissions made by stations with poor connectivity. We show by NS-2 simulations that our mechanism allows to fairly share the bandwidth among stations, even for those with poor radio quality and high packet error rates. Our solution comes with only a few modifications to the frame structure and a change in the acknowledgement semantic.
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Forwarding by Retransmission in IEEE 802.11
2013Co-Authors: Lucien Loiseau, Nicolas Montavont, Xavier LagrangeAbstract:This paper presents a cooperation-based retransmission mechanism for IEEE 802.11 networks called Forwarding By Retransmission (FBR). This mechanism aims at reducing the mean number of Retransmissions in an infrastructure network, or it can be used to forward frames in a small ad hoc network. FBR enables any node that received a frame to participate in the retransmission process, as long as it has a higher probability to reach the destination than the sender. We detail our implementation in NS-2 and analyze the FBR operations in a simple scenario. We show that using only one relay allows reducing the number of Retransmissions by 60%.
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IEEE ANTS - Forwarding by retransmission in IEEE 802.11
2013 IEEE International Conference on Advanced Networks and Telecommunications Systems (ANTS), 2013Co-Authors: Lucien Loiseau, Nicolas Montavont, Xavier LagrangeAbstract:This paper presents a cooperation-based retransmission mechanism for IEEE 802.11 networks called Forwarding By Retransmission (FBR). This mechanism aims at reducing the mean number of Retransmissions in an infrastructure network, or it can be used to forward frames in a small ad hoc network. FBR enables any node that received a frame to participate in the retransmission process, as long as it has a higher probability to reach the destination than the sender. We detail our implementation in NS-2 and analyze the FBR operations in a simple scenario. We show that using only one relay allows reducing the number of Retransmissions by 60%.
Martin Serror - One of the best experts on this subject based on the ideXlab platform.
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channel coding versus cooperative arq reducing outage probability in ultra low latency wireless communications
Global Communications Conference, 2015Co-Authors: Martin Serror, Christian Dombrowski, Klaus Wehrle, James GrossAbstract:Nowadays wireless communications still lack the ability to provide high reliability and low latency, although mission-critical applications, such as found in industrial automation, rely on both requirements. The main challenge is that an improved reliability often comes at the price of an increased latency. It has been shown that cooperative schemes can effectively increase the reliability by leveraging spatial diversity. However, an important question remains how to integrate cooperative schemes when dealing with very short latency bounds and especially how much time should be reserved for potential Retransmissions. In this work, we propose and evaluate a centralized communication system that uses cooperative ARQ to achieve high reliability under the constraint of a strict latency bound of 1 ms. We evaluate this system analytically, using an outage-capacity model with average channel state information, by varying the reserved time for Retransmissions, where a shorter time for Retransmissions allows to apply stronger channel codes in the original transmission. As a baseline, we use a system without cooperation mechanism, thus applying the given time for stronger channel codes in the direct transmission of a message. In case of cooperation, a third station may act as a relay if the original transmission failed. Our results reveal that an optimal size of the reserved retransmission time exists around 15% to 30% of the total frame time, increasing the reliability by several orders of magnitude, even for a large number of transmissions within a communication cycle.
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GLOBECOM Workshops - Channel Coding versus Cooperative ARQ: Reducing Outage Probability in Ultra-Low Latency Wireless Communications
2015 IEEE Globecom Workshops (GC Wkshps), 2015Co-Authors: Martin Serror, Christian Dombrowski, Klaus Wehrle, James GrossAbstract:Nowadays wireless communications still lack the ability to provide high reliability and low latency, although mission-critical applications, such as found in industrial automation, rely on both requirements. The main challenge is that an improved reliability often comes at the price of an increased latency. It has been shown that cooperative schemes can effectively increase the reliability by leveraging spatial diversity. However, an important question remains how to integrate cooperative schemes when dealing with very short latency bounds and especially how much time should be reserved for potential Retransmissions. In this work, we propose and evaluate a centralized communication system that uses cooperative ARQ to achieve high reliability under the constraint of a strict latency bound of 1 ms. We evaluate this system analytically, using an outage-capacity model with average channel state information, by varying the reserved time for Retransmissions, where a shorter time for Retransmissions allows to apply stronger channel codes in the original transmission. As a baseline, we use a system without cooperation mechanism, thus applying the given time for stronger channel codes in the direct transmission of a message. In case of cooperation, a third station may act as a relay if the original transmission failed. Our results reveal that an optimal size of the reserved retransmission time exists around 15% to 30% of the total frame time, increasing the reliability by several orders of magnitude, even for a large number of transmissions within a communication cycle.
