Pub Date : 2002-08-07DOI: 10.1109/VTC.2002.1002587
V. Pohl, V. Jungnickel, T. Haustein, C. Helmolt
We study the relation between antenna spacing and capacity of MIMO channels for indoor environments using a ray tracing program. It has been confirmed also by measurements that in rich scattering environments an antenna spacing below 0.5/spl lambda/ is sufficient to reach nearly the full capacity predicted for multiple-antenna arrays in ideal and uncorrelated Rayleigh fading channels.
{"title":"Antenna spacing in MIMO indoor channels","authors":"V. Pohl, V. Jungnickel, T. Haustein, C. Helmolt","doi":"10.1109/VTC.2002.1002587","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002587","url":null,"abstract":"We study the relation between antenna spacing and capacity of MIMO channels for indoor environments using a ray tracing program. It has been confirmed also by measurements that in rich scattering environments an antenna spacing below 0.5/spl lambda/ is sufficient to reach nearly the full capacity predicted for multiple-antenna arrays in ideal and uncorrelated Rayleigh fading channels.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"349 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":"124303625","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.2002.1002850
S. M. Allen, D. Evans, S. Hurley, R. Whitaker
We investigate the automatic design of efficient wireless communications networks whose nodes exhibit mobility characteristics and where a subset of the nodes must be selected to host servers. The paper describes a representation of the problem, an evolutionary solution framework and some preliminary results.
{"title":"Communications network design with mobility characteristics","authors":"S. M. Allen, D. Evans, S. Hurley, R. Whitaker","doi":"10.1109/VTC.2002.1002850","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002850","url":null,"abstract":"We investigate the automatic design of efficient wireless communications networks whose nodes exhibit mobility characteristics and where a subset of the nodes must be selected to host servers. The paper describes a representation of the problem, an evolutionary solution framework and some preliminary results.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"37 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":"124346492","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.2002.1002593
V. S. Abhayawardhana, I. Wassell
Orthogonal frequency division multiplexing (OFDM) systems are very sensitive to frequency offset caused by tuning oscillator instabilities and Doppler shifts induced by the channel. The Schmidt and Cox (1997) algorithm (SCA) is quite robust in estimating the frequency offset for systems with large OFDM symbol lengths. It uses two OFDM symbols for training with the first one having two identical halves. The frequency offset is estimated by correlating a received sequence of samples equal to half the OFDM symbol length with the following received samples. The effect of additive white Gaussian noise (AWGN) in the estimation process is mitigated only if the number of samples used in the correlation, and hence the OFDM symbol size is large. However to be successfully applied to broadband fixed wireless access (BFWA) systems, OFDM should perform well even with smaller symbol lengths. We present the residual frequency offset correction algorithm (RFOCA), which uses the SCA for initial frequency offset acquisition and follows it with a stage which reduces the initial residual frequency offset by tracking the phase of the decoded data. We show through simulation that the RFOCA achieves an error variance that is many orders of magnitude lower than at the end of the acquisition stage using the SCA alone.
{"title":"Residual frequency offset correction for coherently modulated OFDM systems in wireless communication","authors":"V. S. Abhayawardhana, I. Wassell","doi":"10.1109/VTC.2002.1002593","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002593","url":null,"abstract":"Orthogonal frequency division multiplexing (OFDM) systems are very sensitive to frequency offset caused by tuning oscillator instabilities and Doppler shifts induced by the channel. The Schmidt and Cox (1997) algorithm (SCA) is quite robust in estimating the frequency offset for systems with large OFDM symbol lengths. It uses two OFDM symbols for training with the first one having two identical halves. The frequency offset is estimated by correlating a received sequence of samples equal to half the OFDM symbol length with the following received samples. The effect of additive white Gaussian noise (AWGN) in the estimation process is mitigated only if the number of samples used in the correlation, and hence the OFDM symbol size is large. However to be successfully applied to broadband fixed wireless access (BFWA) systems, OFDM should perform well even with smaller symbol lengths. We present the residual frequency offset correction algorithm (RFOCA), which uses the SCA for initial frequency offset acquisition and follows it with a stage which reduces the initial residual frequency offset by tracking the phase of the decoded data. We show through simulation that the RFOCA achieves an error variance that is many orders of magnitude lower than at the end of the acquisition stage using the SCA alone.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"12 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":"127714981","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.2002.1002958
R. Haines, M. Fitton, T. Farnham
Re-configurable terminals, by definition, are intended to work across multiple telecommunications systems and standards. One of the requirements to be able to achieve this is the ability to monitor levels of coverage in alternative systems. There are limited opportunities for performing alternative mode monitoring within existing standards; therefore other approaches need to be investigated. This paper investigates the concept of co-operative mode monitoring (CoMM), whereby measurements taken by "donor" terminals in the destination mode are presented to the "roaming" terminal.
{"title":"Co-operative solutions for inter-mode monitoring in re-configurable terminals","authors":"R. Haines, M. Fitton, T. Farnham","doi":"10.1109/VTC.2002.1002958","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002958","url":null,"abstract":"Re-configurable terminals, by definition, are intended to work across multiple telecommunications systems and standards. One of the requirements to be able to achieve this is the ability to monitor levels of coverage in alternative systems. There are limited opportunities for performing alternative mode monitoring within existing standards; therefore other approaches need to be investigated. This paper investigates the concept of co-operative mode monitoring (CoMM), whereby measurements taken by \"donor\" terminals in the destination mode are presented to the \"roaming\" terminal.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"37 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":"127768847","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.2002.1002926
F. Alam, Donghee Shim, B. Woerner
We investigate eigen-beamforming resulting from the maximum signal to noise ratio (MSNR) criterion. MSNR beamforming criterion leads to a simple eigenvalue problem (SE) so that the weight vector is the principal eigenvector of the covariance matrix of the desired signal. We employ a beamformer-RAKE receiver at the uplink of a wideband code division multiple access (WCDMA) system. The receiver exploits the MSNR based beamforming for spatial processing. There are different algorithms like the power method, the Lagrange multiplier method and the conjugate gradient method to solve the SE. We compare these three algorithms in terms of computational complexity and bit error rate (BER) performance in multipath propagation environment.
{"title":"Comparison of low complexity algorithms for MSNR beamforming","authors":"F. Alam, Donghee Shim, B. Woerner","doi":"10.1109/VTC.2002.1002926","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002926","url":null,"abstract":"We investigate eigen-beamforming resulting from the maximum signal to noise ratio (MSNR) criterion. MSNR beamforming criterion leads to a simple eigenvalue problem (SE) so that the weight vector is the principal eigenvector of the covariance matrix of the desired signal. We employ a beamformer-RAKE receiver at the uplink of a wideband code division multiple access (WCDMA) system. The receiver exploits the MSNR based beamforming for spatial processing. There are different algorithms like the power method, the Lagrange multiplier method and the conjugate gradient method to solve the SE. We compare these three algorithms in terms of computational complexity and bit error rate (BER) performance in multipath propagation environment.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"5 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":"126485423","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.2002.1002860
N. Hathi, M. Rodrigues, I. Darwazeh, J. O'Reilly
The combination of code division multiple access (CDMA) and multi-carrier modulation (MCM) (referred to as multi-carrier CDMA) has been proposed as a possible candidate for future generations of wireless/mobile systems. Much work has been done on the performance of such schemes in various environments, with different channel models, predominantly assuming linear channels. Accordingly, in this paper we explore the influence of the effects of non-linearities (introduced by the transmitter high power amplifier (HPA)) on multi-carrier CDMA systems using higher order modulation schemes. We consider two techniques for combining CDMA with MCM: multi-carrier CDMA (MC-CDMA) and multi-carrier direct sequence CDMA (MC-DS-CDMA) and analyse their performance in the presence of an HPA and additive white Gaussian noise (AWGN), paying particular attention to the total degradation and the spectral spreading.
{"title":"Performance assessment of MC-CDMA and MC-DS-CDMA in the presence of high power amplifier non-linearities","authors":"N. Hathi, M. Rodrigues, I. Darwazeh, J. O'Reilly","doi":"10.1109/VTC.2002.1002860","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002860","url":null,"abstract":"The combination of code division multiple access (CDMA) and multi-carrier modulation (MCM) (referred to as multi-carrier CDMA) has been proposed as a possible candidate for future generations of wireless/mobile systems. Much work has been done on the performance of such schemes in various environments, with different channel models, predominantly assuming linear channels. Accordingly, in this paper we explore the influence of the effects of non-linearities (introduced by the transmitter high power amplifier (HPA)) on multi-carrier CDMA systems using higher order modulation schemes. We consider two techniques for combining CDMA with MCM: multi-carrier CDMA (MC-CDMA) and multi-carrier direct sequence CDMA (MC-DS-CDMA) and analyse their performance in the presence of an HPA and additive white Gaussian noise (AWGN), paying particular attention to the total degradation and the spectral spreading.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"58 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":"126222431","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.2002.1002854
Lei Huang, F. Zheng
This paper proposes a subspace based blind adaptive channel estimation algorithm for dual-rate DS-CDMA systems, which can operate at the low-rate (LR) or high-rate (HR) mode. Simulation results show that the proposed blind adaptive algorithm at the LR mode has a better performance than that at the HR mode, with the cost of an increased computational complexity.
{"title":"Blind channel estimation for dual-rate DS/CDMA","authors":"Lei Huang, F. Zheng","doi":"10.1109/VTC.2002.1002854","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002854","url":null,"abstract":"This paper proposes a subspace based blind adaptive channel estimation algorithm for dual-rate DS-CDMA systems, which can operate at the low-rate (LR) or high-rate (HR) mode. Simulation results show that the proposed blind adaptive algorithm at the LR mode has a better performance than that at the HR mode, with the cost of an increased computational complexity.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"9 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":"126400308","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.2002.1002864
M. L. Sim, H. Chuah
Transmitter power control is an effective scheme to improve the performance of cellular DS/CDMA systems. In the reverse link, time-multiplexed pilot symbols are used to assist the estimation of received signal power in order to improve the performance of power control. In this paper, two different approaches for received power estimation in power controlled CDMA systems are proposed and compared in terms of bit error rate (BER) by means of analytical and simulation studies. The first power estimator uses a simple sample average and the second power estimator uses a minimum mean square error (MMSE) filter approach. The MMSE approach requires knowledge of the Doppler spread and the signal-to-interference ratio (SIR). Comparison of the performance of the two power estimators is done with respect to deviations in the SIR and Doppler spread as used for the design of the MMSE filter, from their nominal values. Analysis results show that when the MMSE filter approach is used, BER can be further improved as compared to the simple sample average power estimator.
{"title":"Performance evaluation of received power estimation for power control in CDMA systems","authors":"M. L. Sim, H. Chuah","doi":"10.1109/VTC.2002.1002864","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002864","url":null,"abstract":"Transmitter power control is an effective scheme to improve the performance of cellular DS/CDMA systems. In the reverse link, time-multiplexed pilot symbols are used to assist the estimation of received signal power in order to improve the performance of power control. In this paper, two different approaches for received power estimation in power controlled CDMA systems are proposed and compared in terms of bit error rate (BER) by means of analytical and simulation studies. The first power estimator uses a simple sample average and the second power estimator uses a minimum mean square error (MMSE) filter approach. The MMSE approach requires knowledge of the Doppler spread and the signal-to-interference ratio (SIR). Comparison of the performance of the two power estimators is done with respect to deviations in the SIR and Doppler spread as used for the design of the MMSE filter, from their nominal values. Analysis results show that when the MMSE filter approach is used, BER can be further improved as compared to the simple sample average power estimator.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"73 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":"126430297","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.2002.1002598
Q. Liang
This paper presents a method for eliminating adjacent-channel interference (ACI) in satellite-based General Packet Radio Service (GPRS) systems using a new fuzzy adaptive filters (FAF). We validate the reasons for using such a filter by analyzing the Bayesian detector in which some parameter uncertainties exist. A clustering method is used to adaptively design the parameters of the FAF. Simulation results show that the detector based on the new FAF perform better than the maximal-likelihood block phase estimation detector.
{"title":"Eliminating adjacent-channel interference in satellite-based General Packet Radio Service (GPRS) systems","authors":"Q. Liang","doi":"10.1109/VTC.2002.1002598","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002598","url":null,"abstract":"This paper presents a method for eliminating adjacent-channel interference (ACI) in satellite-based General Packet Radio Service (GPRS) systems using a new fuzzy adaptive filters (FAF). We validate the reasons for using such a filter by analyzing the Bayesian detector in which some parameter uncertainties exist. A clustering method is used to adaptively design the parameters of the FAF. Simulation results show that the detector based on the new FAF perform better than the maximal-likelihood block phase estimation detector.","PeriodicalId":159750,"journal":{"name":"Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367)","volume":"2 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":"125698212","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.2002.1002628
Keehong Um, Beongku An
We present a printed planar antenna suitable for mobile wireless communications. Since the printed antenna is easy to fabricate due to its simplicity, low cost, and light weight, it is widely used in communication systems. The conventional patch antennas take too much surface area to be applied to a mobile receiver. Although the size is reduced using the printed antenna, a reasonably wide bandwidth should still be considered. To overcome the disadvantage of narrow bandwidth, the substrate should be physically thick and the dielectric constant should be smaller. We suggest a simple form of printed planar antenna and show the optimal input impedance depending on the antenna size and operating frequency. The performance evaluation is achieved analytically for a prototype antenna model.
{"title":"Design of rectangular printed planar antenna via input impedance for supporting mobile wireless communications","authors":"Keehong Um, Beongku An","doi":"10.1109/VTC.2002.1002628","DOIUrl":"https://doi.org/10.1109/VTC.2002.1002628","url":null,"abstract":"We present a printed planar antenna suitable for mobile wireless communications. Since the printed antenna is easy to fabricate due to its simplicity, low cost, and light weight, it is widely used in communication systems. The conventional patch antennas take too much surface area to be applied to a mobile receiver. Although the size is reduced using the printed antenna, a reasonably wide bandwidth should still be considered. To overcome the disadvantage of narrow bandwidth, the substrate should be physically thick and the dielectric constant should be smaller. We suggest a simple form of printed planar antenna and show the optimal input impedance depending on the antenna size and operating frequency. The performance evaluation is achieved analytically for a prototype antenna model.","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":"130228104","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：