The Experts below are selected from a list of 116835 Experts worldwide ranked by ideXlab platform

Yang Da-cheng - One of the best experts on this subject based on the ideXlab platform.

  • Novel Rate Control Scheme Based on System Load and Channel Quality
    2006 International Conference on Wireless Communications Networking and Mobile Computing, 2006
    Co-Authors: Gao Yuehong, Zhang Xin, Yang Da-cheng
    Abstract:

    In this paper, we propose an adaptive uplink rate control scheme based on the reverse activity bit (RAB) setting at base station (BS) and Channel Quality mobile station (MS) undergoes. According to the RAB and the increment of traffic to pilot ratio (T2P) broadcasted by BS, each MS adaptively adjusts its rate based on the maximum supported T2P in a deterministic manner according to the Channel Quality indication (CQI). It is proved by system level simulation that the proposed adaptive scheme can enlarge system throughput while guaranteeing Quality of service (QoS) and fairness

  • An adaptive reverse link data rate control scheme based on Channel Quality for CDMA system
    Proceedings. 2005 International Conference on Wireless Communications Networking and Mobile Computing 2005., 2005
    Co-Authors: Qin Jie, Zhang Xin, Zhang Yong, Yang Da-cheng
    Abstract:

    The mechanism of the reverse link (RL) data rate control in CDMA system is studied, and a new scheme is presented to enhance the efficiency, which is based not only on probabilistic model, but also on a variable signifying the competitive ability of the mobile station (MS). This variable is related to MS' reverse pilot transmit power, which can reflect the reverse Channel Quality in some sense. With this new mechanism, The MS enjoying better Channel Quality is easier in raising its data transmission rate while the MS undergoing worse Channel Quality is more likely to reduce its rate. Since MS' reverse pilot transmit power is a variable known by MS itself, no extra signaling overhead is required from BS. Through dynamic system level simulation for cdma2000 release D where H-ARQ is employed on RL, the results show that the system throughput on RL is improved by the proposed scheme with the rise over thermal (RoT) value kept on a stable level.

Imad Mahgoub - One of the best experts on this subject based on the ideXlab platform.

  • spatial distribution and Channel Quality adaptive protocol for multihop wireless broadcast routing in vanet
    IEEE Transactions on Mobile Computing, 2013
    Co-Authors: Michael Slavik, Imad Mahgoub
    Abstract:

    Multihop wireless broadcast is an important component in vehicular networks. Many applications are built on broadcast communications, so efficient routing methods are critical for their success. Here, we develop the Distribution-Adaptive Distance with Channel Quality (DADCQ) protocol to address this need and show that it performs well compared to several existing multihop broadcast proposals. The DADCQ protocol utilizes the distance method to select forwarding nodes. The performance of this method depends heavily on the value of the decision threshold, but it is difficult to choose a value that results in good performance across all scenarios. Node density, spatial distribution pattern, and wireless Channel Quality all affect the optimal value. Broadcast protocols tailored to vehicular networking must be adaptive to variation in these factors. In this work, we address this design challenge by creating a decision threshold function that is simultaneously adaptive to the number of neighbors, the node clustering factor, and the Rician fading parameter. To calculate the clustering factor, we propose using the quadrat method of spatial analysis. The resulting DADCQ protocol is then verified with JiST/SWANS and shown to achieve high reachability and low bandwidth consumption in urban and highway scenarios with varying node density and fading intensity.

Rudolf Mathar - One of the best experts on this subject based on the ideXlab platform.

  • SoftCOM - Adaptive Channel Quality feedback for LTE
    2014 22nd International Conference on Software Telecommunications and Computer Networks (SoftCOM), 2014
    Co-Authors: Rudolf Mathar
    Abstract:

    In Long Term Evolution (LTE) networks, resource allocation and link adaptation rely on the Channel Quality indicator (CQI), which is a quantized representation of the signal interference plus noise ratio (SINR). Since CQI is measured by user equipment (UE) and sent to eNodeB via a feedback Channel, in time varying Channel, feedback delay should be compensated with prediction based on previous knowledge. In this work, several known prediction schemes are studied. Moreover, an adaptive CQI feedback scheme based on the sample autocovariance function is proposed. Simulation results show the proposed prediction scheme outperforms the other known prediction schemes in terms of overall prediction accuracy and system throughput. In addition, the performance is evaluated for systems both with and without hybrid automatic repeat request (HARQ), to investigate the influence of HARQ.

  • PIMRC - Autonomous downlink power control for LTE femtocells based on Channel Quality indicator
    2013 IEEE 24th Annual International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 2013
    Co-Authors: Gledi Kutrolli, Rudolf Mathar
    Abstract:

    In this work, a downlink power control scheme based on Channel Quality indicator (CQI) is proposed for LTE femtocells. Unlike the conventional methods, this scheme takes the service types of users into account. Without making strong assumptions, such as full knowledge of the network or perfect coordination among basestations, a completely decentralized solution is provided. Simulation results confirm, that comparing to the conventional schemes, better throughput and coverage can be achieved simultaneously by the proposed algorithm.

  • SoftCOM - Improving QoS by predictive Channel Quality feedback for LTE
    2013 21st International Conference on Software Telecommunications and Computer Networks - (SoftCOM 2013), 2013
    Co-Authors: Rudolf Mathar
    Abstract:

    In Long Term Evolution (LTE) systems, the Quality of service (QoS) heavily relies on the accurate feedback of Channel Quality indicator (CQI). However, the time-varying Channel and transmission delay make the outdated CQI unreliable. In this work, CQI prediction schemes based on Wiener filter, cubic spline extrapolation and short-term average are studied. The effects of using prediction schemes on data throughput are compared with simulation. A simple adaptation technique is found to make the prediction effective for both high speed and low speed mobile stations.

Dongyang Wang - One of the best experts on this subject based on the ideXlab platform.

  • Channel Quality based routing protocol cqbr and realization on manet platform
    International Conference on Telecommunications, 2014
    Co-Authors: Muqing Wu, Wenxing Liao, Dongyang Wang
    Abstract:

    The key factors for a routing protocol in Ad Hoc networks include route discovery, route maintenance and route destroy. Our laboratory has done a lot of researches based on our Ad Hoc hardware platform applying the classical AODV protocol. We found out that an essential cause for unsuccessful route discovery, instable route or even the limitation of hop numbers can be summarized as the bad Channel Quality for the established route. We propose a mechanism of wireless Channel Quality based routing protocol (CQBR). That is during the route discovery process, the RSSI is introduced to value the wireless hop Quality and only those hops with certain signal strength can be choose for the construction of a route. We have realized the CQBR on our platform, including the RSSI generation on the physical layer and the RREQ process on the network layer. The practical test results demonstrate that CQBR has a great improvement in the aspects of more reasonable route, higher throughput, and lower packet loss.

  • ICT - Channel Quality based routing protocol (CQBR) and realization on MANET platform
    2014 21st International Conference on Telecommunications (ICT), 2014
    Co-Authors: Fan Guo, Wenxing Liao, Dongyang Wang
    Abstract:

    The key factors for a routing protocol in Ad Hoc networks include route discovery, route maintenance and route destroy. Our laboratory has done a lot of researches based on our Ad Hoc hardware platform applying the classical AODV protocol. We found out that an essential cause for unsuccessful route discovery, instable route or even the limitation of hop numbers can be summarized as the bad Channel Quality for the established route. We propose a mechanism of wireless Channel Quality based routing protocol (CQBR). That is during the route discovery process, the RSSI is introduced to value the wireless hop Quality and only those hops with certain signal strength can be choose for the construction of a route. We have realized the CQBR on our platform, including the RSSI generation on the physical layer and the RREQ process on the network layer. The practical test results demonstrate that CQBR has a great improvement in the aspects of more reasonable route, higher throughput, and lower packet loss.

Thiemo Voigt - One of the best experts on this subject based on the ideXlab platform.

  • Quantifying the Channel Quality for interference-aware wireless sensor networks
    ACM Sigbed Review, 2011
    Co-Authors: Claro Noda, Shashi Prabh, Carlo Alberto Boano, Mário Alves, Thiemo Voigt
    Abstract:

    Reliability of communications is key to expand application domains for sensor networks. Since Wireless Sensor Networks (WSN) operate in the license-free Industrial Scientific and Medical (ISM) bands and hence share the spectrum with other wireless technologies, addressing interference is an important challenge. In order to minimize its effect, nodes can dynamically adapt radio resources provided information about current spectrum usage is available. We present a new Channel Quality metric, based on availability of the Channel over time, which meaningfully quantifies spectrum usage. We discuss the optimum scanning time for capturing the Channel condition while maintaining energy-efficiency. Using data collected from a number of Wi-Fi networks operating in a library building, we show that our metric has strong correlation with the Packet Reception Rate (PRR). This suggests that quantifying interference in the Channel can help in adapting resources for better reliability. We present a discussion of the usage of our metric for various resource allocation and adaptation strategies.

  • IPSN - Poster abstract: A Channel Quality metric for interference-aware wireless sensor networks
    2011
    Co-Authors: Claro A. Noda, Shashi Prabh, Carlo Alberto Boano, Thiemo Voigt, Mário Alves
    Abstract:

    Wireless sensor networks share the spectrum with other wireless technologies. Hence, in order to minimize the effects of external interference they must carefully choose the Channels for packet transmissions and reception. The identification of the best Channels is, however, non-trivial. In this poster we present and evaluate a new Channel Quality metric that is based on the availability of Channels over time rather than on the average energy in Channels.

  • IPSN - Poster abstract: Exploiting the LQI variance for rapid Channel Quality assessment
    2009
    Co-Authors: Carlo Alberto Boano, Thiemo Voigt, Adam Dunkels, Fredrik Österlind, Nicolas Tsiftes, Luca Mottola, Pablo Suarez
    Abstract:

    Communicating over a reliable radio Channel is vital for an efficient resource usage in sensor networks: a bad radio Channel can lead to poor application performance and higher energy consumption. Previous research has shown that the LQI mean value is a good estimator of the link Quality. Nevertheless, due to its high variance, many packets are needed to obtain a reliable estimation. Based on experimental results, we show instead that the LQI variance is not a limitation. We show that the variance of the LQI can be used as a metric for a rapid Channel Quality assessment. Our initial results indicate that identifying good Channels using the LQI variance requires an order of magnitude fewer packets than when using the mean LQI.