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}
J. Bustillo, S. Tenorio, Beatriz Garriga, Francisco Dominguez
This document presents a new way to carry the Iub traffic in a 3G system through the use of the Uu radio RLC, MAC and WCDMA protocol layers. So, instead of using leased lines, Ethernet, microwave, this system uses its own 3G frequency to carry the traffic between different Nodes B. On top of that, it is possible to form a meshed network among the Nodes B maximizing the use of the lub interface and providing the best experience to the end customers.
{"title":"WCDMA Uu as new 3G Iub interface","authors":"J. Bustillo, S. Tenorio, Beatriz Garriga, Francisco Dominguez","doi":"10.1109/EW.2008.4623885","DOIUrl":"https://doi.org/10.1109/EW.2008.4623885","url":null,"abstract":"This document presents a new way to carry the Iub traffic in a 3G system through the use of the Uu radio RLC, MAC and WCDMA protocol layers. So, instead of using leased lines, Ethernet, microwave, this system uses its own 3G frequency to carry the traffic between different Nodes B. On top of that, it is possible to form a meshed network among the Nodes B maximizing the use of the lub interface and providing the best experience to the end customers.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"1 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":"121841944","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 propose a scalable speech/audio coder control algorithm to improve quality of service (QoS) of voice over IP (VoIP) calls over wireless local area networks (WLANs). There is an upper bound on the number of simultaneous VoIP calls that can be connected in a basic service set (BSS) of 802.11 WLANs which can be composed of an access point (AP) and wireless stations (WSTAs). In the case that there is an upper bound on the number of the calls, even making an additional VoIP call in the BSS which has been already saturated with other calls can severely degrade the quality of all VoIP calls. However, if we can control bit-rates of a speech/audio coder which has variable bit rates to reduce the size of voice packets, as a result, if wireless channel occupancy time which is occupied by an AP and associated wireless LAN stations is reduced, then the additional VoIP call can be gracefully accepted into the BSS with a little degradation of voice quality due to the reduced bit rates. In the same context, we propose a speech/audio coder control algorithm to improve QoS of voice traffic in the case of the additional VoIP call, especially from the point of end-to-end delay.
{"title":"A scalable speech/audio coder control algorithm to improve the Qos of VoIP calls over WLANs","authors":"Ki-Jong Koo, Do-young Kim","doi":"10.1109/EW.2008.4623921","DOIUrl":"https://doi.org/10.1109/EW.2008.4623921","url":null,"abstract":"In this paper, we propose a scalable speech/audio coder control algorithm to improve quality of service (QoS) of voice over IP (VoIP) calls over wireless local area networks (WLANs). There is an upper bound on the number of simultaneous VoIP calls that can be connected in a basic service set (BSS) of 802.11 WLANs which can be composed of an access point (AP) and wireless stations (WSTAs). In the case that there is an upper bound on the number of the calls, even making an additional VoIP call in the BSS which has been already saturated with other calls can severely degrade the quality of all VoIP calls. However, if we can control bit-rates of a speech/audio coder which has variable bit rates to reduce the size of voice packets, as a result, if wireless channel occupancy time which is occupied by an AP and associated wireless LAN stations is reduced, then the additional VoIP call can be gracefully accepted into the BSS with a little degradation of voice quality due to the reduced bit rates. In the same context, we propose a speech/audio coder control algorithm to improve QoS of voice traffic in the case of the additional VoIP call, especially from the point of end-to-end delay.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"50 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":"124948054","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}
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}
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}
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}
D. Hock, N. Bayer, R. Pries, M. Siebert, D. Staehle, V. Rakocevic, Bangnan Xu
WLAN, based on the IEEE 802.11 standard has been extensively studied since its release. In addition to infrastructure access to WLAN, mesh networks currently attract a lot of attention. This comes from the envisioned advantages of wireless mesh networks, such as cheap installation costs, extended coverage, robustness, easy maintenance, and self-configuration possibilities. In this paper we focus on Quality of Service support for multimedia applications in WLAN-based mesh networks. Therefore, a dynamic bandwidth control mechanism is implemented on the network layer and the results show that high prioritized traffic can be protected from disturbing best effort traffic.
{"title":"QoS provisioning in WLAN mesh networks using dynamic bandwidth control","authors":"D. Hock, N. Bayer, R. Pries, M. Siebert, D. Staehle, V. Rakocevic, Bangnan Xu","doi":"10.1109/EW.2008.4623896","DOIUrl":"https://doi.org/10.1109/EW.2008.4623896","url":null,"abstract":"WLAN, based on the IEEE 802.11 standard has been extensively studied since its release. In addition to infrastructure access to WLAN, mesh networks currently attract a lot of attention. This comes from the envisioned advantages of wireless mesh networks, such as cheap installation costs, extended coverage, robustness, easy maintenance, and self-configuration possibilities. In this paper we focus on Quality of Service support for multimedia applications in WLAN-based mesh networks. Therefore, a dynamic bandwidth control mechanism is implemented on the network layer and the results show that high prioritized traffic can be protected from disturbing best effort traffic.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"47 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":"123689311","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}
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}
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