Rubén Badorrey, Á. Hernández-Solana, J. Chóliz, A. Valdovinos, I. Alastruey
UWB technology is especially suitable for location and tracking applications due to its high bandwidth, which allows a great accuracy on Time Of Arrival (TOA) estimation. Nevertheless, the achievement of this goal on multipath environments requires the design of efficient detection algorithms. The main objective of this paper is to compare and to provide a qualitative and quantitative evaluation of different TOA-based distance estimation mechanisms joint to receiver architectures proposed for UWB systems. This comparison has been done in terms of accuracy and the effect of characteristic parameters of the transmitted signal, propagation conditions and signal-to-noise ratio has been analyzed. With this purpose a simulation tool has been developed and the different receiver architectures and estimation mechanisms have been implemented, as well as the different channel models proposed on 802.15.4a.
{"title":"Evaluation of TOA estimation algorithms in UWB receivers","authors":"Rubén Badorrey, Á. Hernández-Solana, J. Chóliz, A. Valdovinos, I. Alastruey","doi":"10.1109/EW.2008.4623872","DOIUrl":"https://doi.org/10.1109/EW.2008.4623872","url":null,"abstract":"UWB technology is especially suitable for location and tracking applications due to its high bandwidth, which allows a great accuracy on Time Of Arrival (TOA) estimation. Nevertheless, the achievement of this goal on multipath environments requires the design of efficient detection algorithms. The main objective of this paper is to compare and to provide a qualitative and quantitative evaluation of different TOA-based distance estimation mechanisms joint to receiver architectures proposed for UWB systems. This comparison has been done in terms of accuracy and the effect of characteristic parameters of the transmitted signal, propagation conditions and signal-to-noise ratio has been analyzed. With this purpose a simulation tool has been developed and the different receiver architectures and estimation mechanisms have been implemented, as well as the different channel models proposed on 802.15.4a.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126674761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Near optimum iterative decoding of block codes in multiple input multiple output (MIMO) systems is proposed and analyzed applying a new suboptimal space time soft input soft output detector and Chase Pyndiah decoder for FEC detection. The suboptimal space time detector applies zero forcing detection to estimate the center and radius of the hyper-sphere which determines a subset of the most probable transmitted symbol vectors. The soft values are calculated considering only the symbol vectors in the subset, which reduces the computational complexity of the algorithm to 11% at high SNR compared to the standard soft information estimation. The computer simulations modeling IEEE 802.16 standard for broadband wireless access show, that the system performance is decreased less than 1dB compared to ML solution.
{"title":"Near optimum iterative decoding of block codes in MIMO Systems","authors":"I. Jelovcan, G. Kandus, T. Javornik","doi":"10.1109/EW.2008.4623864","DOIUrl":"https://doi.org/10.1109/EW.2008.4623864","url":null,"abstract":"Near optimum iterative decoding of block codes in multiple input multiple output (MIMO) systems is proposed and analyzed applying a new suboptimal space time soft input soft output detector and Chase Pyndiah decoder for FEC detection. The suboptimal space time detector applies zero forcing detection to estimate the center and radius of the hyper-sphere which determines a subset of the most probable transmitted symbol vectors. The soft values are calculated considering only the symbol vectors in the subset, which reduces the computational complexity of the algorithm to 11% at high SNR compared to the standard soft information estimation. The computer simulations modeling IEEE 802.16 standard for broadband wireless access show, that the system performance is decreased less than 1dB compared to ML solution.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128377072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
End-to-end delay is an important parameter in evaluating the performance of multihop ad hoc networks. To improve that, an efficient queue management scheme should be developed. Most existing queue management schemes do not take into account the number of hops that a packet traversed to reach its destination. In this paper, an efficient queue management scheme is proposed. The principal feature of the proposed scheme is to reduce the loss probability of the packets with large number of hops, by assigning more buffer space for those packets. This will lead to decrease the end-to-end delay and energy consumption. A Markovian model, is proposed to investigate the performance of the proposed scheme and to demonstrate that effective queueing scheme can improve the performance of ad hoc networks. The numerical results show that the proposed scheme outperforms the drop tail scheme in terms of end-to-end delay and loss probability.
{"title":"Modeling of an efficient queue management scheme for multihop ad hoc networks","authors":"M. Kalil, H. Al-Mahdi, A. Mitschele-Thiel","doi":"10.1109/EW.2008.4623868","DOIUrl":"https://doi.org/10.1109/EW.2008.4623868","url":null,"abstract":"End-to-end delay is an important parameter in evaluating the performance of multihop ad hoc networks. To improve that, an efficient queue management scheme should be developed. Most existing queue management schemes do not take into account the number of hops that a packet traversed to reach its destination. In this paper, an efficient queue management scheme is proposed. The principal feature of the proposed scheme is to reduce the loss probability of the packets with large number of hops, by assigning more buffer space for those packets. This will lead to decrease the end-to-end delay and energy consumption. A Markovian model, is proposed to investigate the performance of the proposed scheme and to demonstrate that effective queueing scheme can improve the performance of ad hoc networks. The numerical results show that the proposed scheme outperforms the drop tail scheme in terms of end-to-end delay and loss probability.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130985627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the well-known distributed target-SIR tracking power control algorithm, when the target-SIR requirements are not reachable for all users (due to heavy load and/or deep fading), some users transmit at maximum power without reaching their target SIR. Such users inefficiently consume their energies, and introduce unnecessary interference to others, which in turn results in more unnecessary non-supported users. To alleviate the situation, a minimal number of users have to be removed (the gradual removal problem). In this paper, we propose improvements to two algorithms that were shown to be the best of the existing distributed power control algorithms for the gradual removal problem, and demonstrate that the improved algorithms have smaller outage probabilities. In addition, we show that the convergence rate for one of our improved algorithms is substantially better than those of both original algorithms.
{"title":"Improved distributed power control algorithms with gradual removal in wireless networks","authors":"M. Rasti, A. Sharafat, J. Zander","doi":"10.1109/EW.2008.4623869","DOIUrl":"https://doi.org/10.1109/EW.2008.4623869","url":null,"abstract":"In the well-known distributed target-SIR tracking power control algorithm, when the target-SIR requirements are not reachable for all users (due to heavy load and/or deep fading), some users transmit at maximum power without reaching their target SIR. Such users inefficiently consume their energies, and introduce unnecessary interference to others, which in turn results in more unnecessary non-supported users. To alleviate the situation, a minimal number of users have to be removed (the gradual removal problem). In this paper, we propose improvements to two algorithms that were shown to be the best of the existing distributed power control algorithms for the gradual removal problem, and demonstrate that the improved algorithms have smaller outage probabilities. In addition, we show that the convergence rate for one of our improved algorithms is substantially better than those of both original algorithms.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129581968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For evolution of the GSM/EDGE radio access network (RAN), the use of higher order modulation like 16- and 32-ary quadrature amplitude modulation (QAM) is considered in standardization for increased peak data rates and reduced transmission delays. In this paper, an optimized receiver design for different packet data transmission schemes is proposed. Turbo coding and turbo equalization is discussed for improved power efficiency and interference robustness. An efficient complexity reduction of the equalizer enables the usage of turbo equalization at a complexity comparable to that of separate equalization and decoding for turbo-coded transmission.
{"title":"Turbo equalization for evolved GSM/EDGE radio access network using higher order modulation","authors":"P. Nickel, W. Gerstacker, C. Reck, W. Koch","doi":"10.1109/EW.2008.4623865","DOIUrl":"https://doi.org/10.1109/EW.2008.4623865","url":null,"abstract":"For evolution of the GSM/EDGE radio access network (RAN), the use of higher order modulation like 16- and 32-ary quadrature amplitude modulation (QAM) is considered in standardization for increased peak data rates and reduced transmission delays. In this paper, an optimized receiver design for different packet data transmission schemes is proposed. Turbo coding and turbo equalization is discussed for improved power efficiency and interference robustness. An efficient complexity reduction of the equalizer enables the usage of turbo equalization at a complexity comparable to that of separate equalization and decoding for turbo-coded transmission.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129584274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rodolfo Oliveira, Luís Bernardo, Paulo Pinto, R. Dinis
In a beaconing scheme (BS) each network node periodically broadcasts messages (beacons) to obtain and maintain an image of the network physical topology. Nodepsilas mobility and issues related with the communication process could degrade the BS view accuracy. This work proposes a novel method to improve the BS robustness face to the communication process drawbacks. Assuming a homogeneous traffic load, each node uses the information given by the medium access control (MAC) layer to dynamically adapt the Beaconing Timeout value. Several simulation results evaluate the adaptive method performance using the IEEE 802.11b DCF protocol. We conclude that the BS accuracy can be improved even when nodepsilas mobility is assumed.
{"title":"A load-adaptive timeout for beaconing-based link protocols in ad hoc networks","authors":"Rodolfo Oliveira, Luís Bernardo, Paulo Pinto, R. Dinis","doi":"10.1109/EW.2008.4623859","DOIUrl":"https://doi.org/10.1109/EW.2008.4623859","url":null,"abstract":"In a beaconing scheme (BS) each network node periodically broadcasts messages (beacons) to obtain and maintain an image of the network physical topology. Nodepsilas mobility and issues related with the communication process could degrade the BS view accuracy. This work proposes a novel method to improve the BS robustness face to the communication process drawbacks. Assuming a homogeneous traffic load, each node uses the information given by the medium access control (MAC) layer to dynamically adapt the Beaconing Timeout value. Several simulation results evaluate the adaptive method performance using the IEEE 802.11b DCF protocol. We conclude that the BS accuracy can be improved even when nodepsilas mobility is assumed.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128967980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Scheduling algorithms are of utmost importance in WiMAX for efficient use of radio resources. A scheduling algorithm should take into account the WiMAX QoS classes and service requirements. It should also provide high throughput. In this paper, we propose a review of scheduling algorithms proposed for WiMAX. We focus on the real-time Polling Service (rtPS) QoS class. NS-2 simulations show interesting results. We highlight a problem that may exist with the WiMAX rtPS QoS class and we provide solutions for it. Simulation results concerning proposed WiMAX schedulers are discussed. We propose an enhancement of the maximum Signal-to-Interference Ratio (mSIR) scheduler, called modified maximum Signal-to-Interference Ratio (mmSIR). We show through extensive simulations that this enhancement provides better mean sojourn time in addition to an improvement in throughput.
{"title":"Comparison of WiMAX scheduling algorithms and proposals for the rtPS QoS class","authors":"A. Belghith, L. Nuaymi","doi":"10.1109/EW.2008.4623857","DOIUrl":"https://doi.org/10.1109/EW.2008.4623857","url":null,"abstract":"Scheduling algorithms are of utmost importance in WiMAX for efficient use of radio resources. A scheduling algorithm should take into account the WiMAX QoS classes and service requirements. It should also provide high throughput. In this paper, we propose a review of scheduling algorithms proposed for WiMAX. We focus on the real-time Polling Service (rtPS) QoS class. NS-2 simulations show interesting results. We highlight a problem that may exist with the WiMAX rtPS QoS class and we provide solutions for it. Simulation results concerning proposed WiMAX schedulers are discussed. We propose an enhancement of the maximum Signal-to-Interference Ratio (mSIR) scheduler, called modified maximum Signal-to-Interference Ratio (mmSIR). We show through extensive simulations that this enhancement provides better mean sojourn time in addition to an improvement in throughput.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134620402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multiple input multiple output (MIMO) detection methods are derived with an assumption that the noise power of all receiving paths are equal. This assumption is not valid in practical systems performing automatic gain control (AGC) which adjusts the signal level to the dynamic range of analog to digital converters (ADC). If the independent AGC scheme with the different gain for each receiving path to minimize the quantization noise is used, the output noise of AGC is not white in the spatial domain, i.e. the noise variances of receiving paths are not identical. Therefore, this spatially colored noise effects should be taken into consideration for the optimal detection.
{"title":"MIMO detection methods considering AGC effects","authors":"Myung-Soon Kim, Jin-up Kim","doi":"10.1109/EW.2008.4623854","DOIUrl":"https://doi.org/10.1109/EW.2008.4623854","url":null,"abstract":"Multiple input multiple output (MIMO) detection methods are derived with an assumption that the noise power of all receiving paths are equal. This assumption is not valid in practical systems performing automatic gain control (AGC) which adjusts the signal level to the dynamic range of analog to digital converters (ADC). If the independent AGC scheme with the different gain for each receiving path to minimize the quantization noise is used, the output noise of AGC is not white in the spatial domain, i.e. the noise variances of receiving paths are not identical. Therefore, this spatially colored noise effects should be taken into consideration for the optimal detection.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133517679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High speed downlink packet access (HSDPA) provides increased user data rate by introducing additional functionalities at the Node B, such as fast packet scheduling based on the instantaneous radio link quality. One of the algorithms that is able to provide this capability is the proportional fair (P-FR) scheduler. In this paper we describe an approximate analysis method for the mean throughput of the proportional fair scheduler with two traffic classes. We extend the existing results that are based on the assumption of continuous rate distributions to the more realistic discrete distributions. The analysis with discrete distributions entails two problems that do not appear in the continuous case, namely that the priority of several users can be equal with a non-zero probability and that the sample path of throughputs does not always converge to a mean throughput. The proposed approximate method is evaluated with NS2 simulations.
{"title":"Throughput analysis of the proportional fair scheduler in HSDPA","authors":"G. Horváth, C. Vulkán","doi":"10.1109/EW.2008.4623914","DOIUrl":"https://doi.org/10.1109/EW.2008.4623914","url":null,"abstract":"High speed downlink packet access (HSDPA) provides increased user data rate by introducing additional functionalities at the Node B, such as fast packet scheduling based on the instantaneous radio link quality. One of the algorithms that is able to provide this capability is the proportional fair (P-FR) scheduler. In this paper we describe an approximate analysis method for the mean throughput of the proportional fair scheduler with two traffic classes. We extend the existing results that are based on the assumption of continuous rate distributions to the more realistic discrete distributions. The analysis with discrete distributions entails two problems that do not appear in the continuous case, namely that the priority of several users can be equal with a non-zero probability and that the sample path of throughputs does not always converge to a mean throughput. The proposed approximate method is evaluated with NS2 simulations.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131520319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we aim to provide an analytical modeling of cyclic delay diversity in an OFDMA based system. Cyclic delay diversity is a low complexity spatial diversity scheme where multiple transmit antennas transmit delayed versions the same signal. While CDD increases the frequency selectivity, the reduced coherence bandwidth resulted in higher requirements for the channel estimation at the receiver. This paper presents a preliminary model with objective of providing tradeoff study of maximum tolerable cyclic delay value vs. performance impacts to the system.
{"title":"Cyclic delay diversity performance in OFDMA based system","authors":"Chao Wei, Teck H. Hu, Xiao-hu You","doi":"10.1109/EW.2008.4623890","DOIUrl":"https://doi.org/10.1109/EW.2008.4623890","url":null,"abstract":"In this paper, we aim to provide an analytical modeling of cyclic delay diversity in an OFDMA based system. Cyclic delay diversity is a low complexity spatial diversity scheme where multiple transmit antennas transmit delayed versions the same signal. While CDD increases the frequency selectivity, the reduced coherence bandwidth resulted in higher requirements for the channel estimation at the receiver. This paper presents a preliminary model with objective of providing tradeoff study of maximum tolerable cyclic delay value vs. performance impacts to the system.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131572442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：