Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002543
Cheol-Yong Ahn, Jin-Kyu Han, Young-Kwan Choi, Dong Ku Kim
The investigation into the effect of various feedback errors on system performance can help the robust feedback channel design and transmission of exact feedback channel information as well. We address the algorithm that determines space combining weight vector maximizing received signal power at the mobile on a frequency flat fading channel and investigate the performance degradation by the feedback channel delay in the FDD/CDMA systems employing transmit beamforming. We observe the effect of feedback channel delay corresponding to the number of transmit antennas and the temporal/spatial correlation of channel. The results show that performance is more sensitive to feedback delay with the larger number of antennas when fading at the transmit antennas are not spatially correlated.
{"title":"Sensitivity of feedback channel delay on transmit adaptive array","authors":"Cheol-Yong Ahn, Jin-Kyu Han, Young-Kwan Choi, Dong Ku Kim","doi":"10.1109/VTC.2002.1002543","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002543","url":null,"abstract":"The investigation into the effect of various feedback errors on system performance can help the robust feedback channel design and transmission of exact feedback channel information as well. We address the algorithm that determines space combining weight vector maximizing received signal power at the mobile on a frequency flat fading channel and investigate the performance degradation by the feedback channel delay in the FDD/CDMA systems employing transmit beamforming. We observe the effect of feedback channel delay corresponding to the number of transmit antennas and the temporal/spatial correlation of channel. The results show that performance is more sensitive to feedback delay with the larger number of antennas when fading at the transmit antennas are not spatially correlated.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133759434","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002971
E. Costamagna, L. Favalli, P. Gamba, F. Tarantola
The paper relates to some developments in modeling attenuation time series, measured on Ka band satellite links during rain events, by means of sample generators using chaotic dynamical systems. Weighted sums of Lorenz strange attractors are first used to model target sequences by themselves ("global approach"), improving procedures already introduced. Then, similar generators are used to model only low-pass versions of the same sequences, while hidden Markov models (HMM) or shaped random number series are used to mimic the complementary high-pass sequences.
{"title":"Improving chaos equations fading models for Ka band satellite links","authors":"E. Costamagna, L. Favalli, P. Gamba, F. Tarantola","doi":"10.1109/VTC.2002.1002971","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002971","url":null,"abstract":"The paper relates to some developments in modeling attenuation time series, measured on Ka band satellite links during rain events, by means of sample generators using chaotic dynamical systems. Weighted sums of Lorenz strange attractors are first used to model target sequences by themselves (\"global approach\"), improving procedures already introduced. Then, similar generators are used to model only low-pass versions of the same sequences, while hidden Markov models (HMM) or shaped random number series are used to mimic the complementary high-pass sequences.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115802496","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002622
Yongsuk Kim, B. Zhen
This paper proposes a new mechanism for Bluetooth connectionless broadcast channel and concept of net access point (NAP) segment. They are used to track location of idle personal area network users (PANU) in power and radio resource save manner. The connectionless broadcast channel is separated into beacon window and broadcast window. During the beacon window, NAP spreads an extended ID packet that includes BD ADDR and clock offset to synchronize all PANU in its radio range. The Extended ID packet is the standard ID packet with extra information field at the end. Then, any user-defined information is released in the broadcast window from NAP to PANU without connection establishment between NAP and PANU. The NAP segment is a set of geography neighbor NAP. When an idle PANU moves within a NAP segment, no handover is needed even when the current connection breaks. When an idle PANU moves across the NAP segment, handover must be performed to register the PANU's location. We present an analysis of PANU mobility with and without the NAP segment to show that the NAP segment can save the radio resources of the NAP and power consumption of the PANU.
{"title":"Connectionless broadcast channel and mobility of Bluetooth","authors":"Yongsuk Kim, B. Zhen","doi":"10.1109/VTC.2002.1002622","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002622","url":null,"abstract":"This paper proposes a new mechanism for Bluetooth connectionless broadcast channel and concept of net access point (NAP) segment. They are used to track location of idle personal area network users (PANU) in power and radio resource save manner. The connectionless broadcast channel is separated into beacon window and broadcast window. During the beacon window, NAP spreads an extended ID packet that includes BD ADDR and clock offset to synchronize all PANU in its radio range. The Extended ID packet is the standard ID packet with extra information field at the end. Then, any user-defined information is released in the broadcast window from NAP to PANU without connection establishment between NAP and PANU. The NAP segment is a set of geography neighbor NAP. When an idle PANU moves within a NAP segment, no handover is needed even when the current connection breaks. When an idle PANU moves across the NAP segment, handover must be performed to register the PANU's location. We present an analysis of PANU mobility with and without the NAP segment to show that the NAP segment can save the radio resources of the NAP and power consumption of the PANU.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114749249","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002974
L. Husson, J. Dany, Sylvain Chambon, Karim Berradi, Armando Beffani
In order to guarantee the quality of service of satellite communication systems, the effective design must take into account the characteristics of the propagation channels. We focus on the methodology of extraction of the relevant parameters for Markov models corresponding to the received signals of satellite transmissions. Our approach is empirical in the following sense: rather than postulate a priori number of states or probability laws for the instantaneous received power, we try to estimate these laws by processing available experimental signals from the considered channel. The method, used on transmissions in the L-band, is general as it can be applied to various types of signals with a Markovian underlying variability.
{"title":"Modeling of mobile satellite channels by scalable clustering algorithm","authors":"L. Husson, J. Dany, Sylvain Chambon, Karim Berradi, Armando Beffani","doi":"10.1109/VTC.2002.1002974","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002974","url":null,"abstract":"In order to guarantee the quality of service of satellite communication systems, the effective design must take into account the characteristics of the propagation channels. We focus on the methodology of extraction of the relevant parameters for Markov models corresponding to the received signals of satellite transmissions. Our approach is empirical in the following sense: rather than postulate a priori number of states or probability laws for the instantaneous received power, we try to estimate these laws by processing available experimental signals from the considered channel. The method, used on transmissions in the L-band, is general as it can be applied to various types of signals with a Markovian underlying variability.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114936620","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002768
D. Porrat, D. Cox
Waveguide theory is suggested for the analysis of UHF radiation in urban microcellular environments, where both the transmitter and the receiver are below rooftop level. The delay profile is calculated from the steady state power distribution among the modes of the waveguide. The delay profile is very asymmetrical because most of the power is contained in the low order (faster) modes, and because the differences between the group velocities of the modes tend to be smaller for the low order modes.
{"title":"Delay spread in microcells analysed with waveguide theory","authors":"D. Porrat, D. Cox","doi":"10.1109/VTC.2002.1002768","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002768","url":null,"abstract":"Waveguide theory is suggested for the analysis of UHF radiation in urban microcellular environments, where both the transmitter and the receiver are below rooftop level. The delay profile is calculated from the steady state power distribution among the modes of the waveguide. The delay profile is very asymmetrical because most of the power is contained in the low order (faster) modes, and because the differences between the group velocities of the modes tend to be smaller for the low order modes.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115027615","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002873
Lei Cao, C. Chen, P. Orlik, Jinyun Zhang, Daqing Gu
In this paper, a trellis based blind channel estimation and equalization technique is presented. First, blind channel estimation is accomplished by incorporating a list parallel Viterbi algorithm with the least mean square (LMS) updating approach. In this operation, multiple trellis mappings are preserved and ranked in terms of path metrics. Equivalently, multiple channel estimates are maintained and updated once a single symbol is received. Second, at a certain point, which is determined by the evolution of path metrics and the linear constraint possessed in the trellis mapping, only the best channel estimate is maintained. Third, this channel estimate is adopted to construct the whole trellis that is used by a conventional adaptive Viterbi algorithm. Signal detection and further channel updating are then conducted alternatively. To alleviate the noise impact, a small delay is introduced before the feedback of detected symbols to further update the channel estimate. Simulation has shown the overall good performance of the proposed scheme in terms of mean square error (MSE) convergence of the channel estimation, stability to the initial channel guess, and computational complexity etc.
{"title":"Blind channel estimation and equalization using Viterbi algorithms","authors":"Lei Cao, C. Chen, P. Orlik, Jinyun Zhang, Daqing Gu","doi":"10.1109/VTC.2002.1002873","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002873","url":null,"abstract":"In this paper, a trellis based blind channel estimation and equalization technique is presented. First, blind channel estimation is accomplished by incorporating a list parallel Viterbi algorithm with the least mean square (LMS) updating approach. In this operation, multiple trellis mappings are preserved and ranked in terms of path metrics. Equivalently, multiple channel estimates are maintained and updated once a single symbol is received. Second, at a certain point, which is determined by the evolution of path metrics and the linear constraint possessed in the trellis mapping, only the best channel estimate is maintained. Third, this channel estimate is adopted to construct the whole trellis that is used by a conventional adaptive Viterbi algorithm. Signal detection and further channel updating are then conducted alternatively. To alleviate the noise impact, a small delay is introduced before the feedback of detected symbols to further update the channel estimate. Simulation has shown the overall good performance of the proposed scheme in terms of mean square error (MSE) convergence of the channel estimation, stability to the initial channel guess, and computational complexity etc.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116291183","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002601
Jürgen F. Rößler, L. Lampe, W. Gerstacker, J. Huber
A well-known receiver strategy for a linearly modulated signal transmitted over a frequency-selective channel is channel equalization. Recently it was proposed to employ a minimum mean-squared error (MMSE) channel equalizer for the downlink of CDMA. In this paper, we introduce a new receiver concept using MMSE channel equalization as a first stage and MMSE decision-feedback equalization (DFE) utilizing soft feedback from the decoding unit as a second stage. Both schemes are compared for the downlink of CDMA. It turns out, that after channel decoding we gain about 1 dB compared to conventional MMSE channel equalization.
{"title":"Decision-feedback equalization for CDMA downlink","authors":"Jürgen F. Rößler, L. Lampe, W. Gerstacker, J. Huber","doi":"10.1109/VTC.2002.1002601","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002601","url":null,"abstract":"A well-known receiver strategy for a linearly modulated signal transmitted over a frequency-selective channel is channel equalization. Recently it was proposed to employ a minimum mean-squared error (MMSE) channel equalizer for the downlink of CDMA. In this paper, we introduce a new receiver concept using MMSE channel equalization as a first stage and MMSE decision-feedback equalization (DFE) utilizing soft feedback from the decoding unit as a second stage. Both schemes are compared for the downlink of CDMA. It turns out, that after channel decoding we gain about 1 dB compared to conventional MMSE channel equalization.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123605073","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002692
A. Tonello, S. Pupolin
We consider a multitone multiple access wireless system where users are multiplexed by the assignment of sub-sets of the available tones. The information signals of distinct users are multicarrier modulated and propagate through asynchronous frequency selective fading channels, i.e., uplink. In this scenario intersymbol, intercarrier, and multiple access interference arise. We consider simple single user detection and study its performance in terms of outage probability. In particular we investigate the effect on outage probability of the choice of the sub-channel transmit filters and the tone allocation strategy.
{"title":"Performance of single user detectors in multitone multiple access asynchronous communications","authors":"A. Tonello, S. Pupolin","doi":"10.1109/VTC.2002.1002692","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002692","url":null,"abstract":"We consider a multitone multiple access wireless system where users are multiplexed by the assignment of sub-sets of the available tones. The information signals of distinct users are multicarrier modulated and propagate through asynchronous frequency selective fading channels, i.e., uplink. In this scenario intersymbol, intercarrier, and multiple access interference arise. We consider simple single user detection and study its performance in terms of outage probability. In particular we investigate the effect on outage probability of the choice of the sub-channel transmit filters and the tone allocation strategy.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123678417","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002596
R. R. Araujo, F. Cavalcanti, J. Mota, B. Dorizzi
We discuss the use of a dynamic packet to time-slot assignment (DPA) algorithm combined with a nonlinear interference suppression method for a TDMA-based network equipped with an antenna array in the base station. Single and multicell cell scenarios are considered. The whole receiver strategy (combined DPA and non-linear spatial processing) is then evaluated for different degrees of spatial diversity. Results show that the combined strategy produces a considerable throughput improvement, specially for a high offered load condition.
{"title":"Combined dynamic channel assignment and non-linear spatial processing for high throughput packet radio","authors":"R. R. Araujo, F. Cavalcanti, J. Mota, B. Dorizzi","doi":"10.1109/VTC.2002.1002596","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002596","url":null,"abstract":"We discuss the use of a dynamic packet to time-slot assignment (DPA) algorithm combined with a nonlinear interference suppression method for a TDMA-based network equipped with an antenna array in the base station. Single and multicell cell scenarios are considered. The whole receiver strategy (combined DPA and non-linear spatial processing) is then evaluated for different degrees of spatial diversity. Results show that the combined strategy produces a considerable throughput improvement, specially for a high offered load condition.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123687760","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}
Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002970
M. Vázquez-Castro, E. Parrado-Hernández, D. Belay-Zeleke, F. Pérez-Fontán
We focus on a non-GEO scenario and investigate the effect of actual power control performance on the return capacity dynamics of a DS-CDMA system. We consider mobile users at different speeds and transmission rates yielding several classes of services. We compute analytically the ideal maximum return capacity of the system which is shown not to be fixed but limited by a hyperplane in the space of the considered quality of service (QoS), so that different resource assignment criteria can be applied. At maximum ideal capacity, for the different percentages of users that can be served, it is shown that the more restraining the QoS, the more resources that must be assigned. We then explore the appropriate efficiency of the system, i.e. the actual used resources as a function of the distribution of QoS. We finally look into the inter-beam effect by applying different degrees of diversity gains and we show the trade-off between improving the capacity efficiency which is poor due to power control error and the net capacity achieved by the overall system.
{"title":"CDMA satellite capacity dynamics and efficiency with imperfect power control for simultaneous QoS classes and diversity","authors":"M. Vázquez-Castro, E. Parrado-Hernández, D. Belay-Zeleke, F. Pérez-Fontán","doi":"10.1109/VTC.2002.1002970","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002970","url":null,"abstract":"We focus on a non-GEO scenario and investigate the effect of actual power control performance on the return capacity dynamics of a DS-CDMA system. We consider mobile users at different speeds and transmission rates yielding several classes of services. We compute analytically the ideal maximum return capacity of the system which is shown not to be fixed but limited by a hyperplane in the space of the considered quality of service (QoS), so that different resource assignment criteria can be applied. At maximum ideal capacity, for the different percentages of users that can be served, it is shown that the more restraining the QoS, the more resources that must be assigned. We then explore the appropriate efficiency of the system, i.e. the actual used resources as a function of the distribution of QoS. We finally look into the inter-beam effect by applying different degrees of diversity gains and we show the trade-off between improving the capacity efficiency which is poor due to power control error and the net capacity achieved by the overall system.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123998349","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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