Pub Date : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371803
Patrick Hosein
We consider the information-theoretic sum capacity of the reverse link of a CDMA wireless network. In particular we consider the problem of maximizing the throughput of this channel. The decision variables are the transmission powers that are allocated to the mobiles in the network. The major contribution of this paper is the derivation of thresholds that determine when it is: (a) optimal to serve only a single user; and (b) optimal to simultaneously serve multiple users. We also derive the optimal power allocations for the case where users are provided guaranteed minimum rates. Finally we provide a numerical example where we compare the gains of scheduling subsets of users at a time instead of all users simultaneously while maintaining some degree of fairness.
{"title":"Optimality conditions for throughput maximization on the reverse link of a CDMA network","authors":"Patrick Hosein","doi":"10.1109/ISSSTA.2004.1371803","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371803","url":null,"abstract":"We consider the information-theoretic sum capacity of the reverse link of a CDMA wireless network. In particular we consider the problem of maximizing the throughput of this channel. The decision variables are the transmission powers that are allocated to the mobiles in the network. The major contribution of this paper is the derivation of thresholds that determine when it is: (a) optimal to serve only a single user; and (b) optimal to simultaneously serve multiple users. We also derive the optimal power allocations for the case where users are provided guaranteed minimum rates. Finally we provide a numerical example where we compare the gains of scheduling subsets of users at a time instead of all users simultaneously while maintaining some degree of fairness.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130777580","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371823
Lars Schmitt, T. Grundler, Christoph Schreyoegg, Ingo Viering, Heinrich Meyr
Recently, an analytical expression for the mean bit error probability of a binary modulated signal has been derived for a receiver performing maximum ratio combining of correlated diversity branches based on imperfect channel state information. We extend these results to the general case of colored additive noise. Furthermore, an alternative solution is derived which yields numerically stable results also in the case of the respective channel and interference covariance matrices having closely-spaced or multi-fold eigenvalues. Finally, the results are applied to a spatio-temporal W-CDMA RAKE receiver, where the effects of multiple-access-interference (MAI) and interpath interference (IPI), due to multipath propagation, on the mean bit error probability are investigated.
{"title":"Maximum ratio combining of correlated diversity branches with imperfect channel state information and colored noise","authors":"Lars Schmitt, T. Grundler, Christoph Schreyoegg, Ingo Viering, Heinrich Meyr","doi":"10.1109/ISSSTA.2004.1371823","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371823","url":null,"abstract":"Recently, an analytical expression for the mean bit error probability of a binary modulated signal has been derived for a receiver performing maximum ratio combining of correlated diversity branches based on imperfect channel state information. We extend these results to the general case of colored additive noise. Furthermore, an alternative solution is derived which yields numerically stable results also in the case of the respective channel and interference covariance matrices having closely-spaced or multi-fold eigenvalues. Finally, the results are applied to a spatio-temporal W-CDMA RAKE receiver, where the effects of multiple-access-interference (MAI) and interpath interference (IPI), due to multipath propagation, on the mean bit error probability are investigated.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115548498","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371688
K. Arshad, A. Sheikh
Orthogonal frequency division multiplexing (OFDM) is well-known to be effective against multipath distortion. Channel estimation for mobile OFDM systems requires transmission of pilot symbols. The paper addresses the important issue of selecting the location of these pilot symbols to achieve low error rates. It addresses the effect of Doppler spread of the channel on different pilot arrangements and proposes a new scheme for inserting pilot symbols. It is shown that, for pedestrian channels, the proposed scheme performs better than other pilot insertion schemes.
{"title":"Performance of wireless OFDM system channel estimation with different pilot patterns","authors":"K. Arshad, A. Sheikh","doi":"10.1109/ISSSTA.2004.1371688","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371688","url":null,"abstract":"Orthogonal frequency division multiplexing (OFDM) is well-known to be effective against multipath distortion. Channel estimation for mobile OFDM systems requires transmission of pilot symbols. The paper addresses the important issue of selecting the location of these pilot symbols to achieve low error rates. It addresses the effect of Doppler spread of the channel on different pilot arrangements and proposes a new scheme for inserting pilot symbols. It is shown that, for pedestrian channels, the proposed scheme performs better than other pilot insertion schemes.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"173 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116302989","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371782
S. Siltala, M. Juntti
A side information generating algorithm for iterative decoding in frequency-hopping spread-spectrum (FH-SS) is proposed. In the algorithm, the channel state probabilities are iteratively calculated with an extension of the Kang-Stark algorithm. Differential encoded phase shift keying (DPSK) is employed with the noncoherent expanded trellis based iterative receiver. The performance of the proposed algorithm with the convolutionally coded system is evaluated by simulation and compared with a system using a ratio threshold test (RTT) for PSK. The results show that the performance of the introduced algorithm is similar to the system with perfect jamming state information and provides better side information than RTT.
{"title":"Side information for noncoherent FH-SS DPSK in partial-band jamming","authors":"S. Siltala, M. Juntti","doi":"10.1109/ISSSTA.2004.1371782","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371782","url":null,"abstract":"A side information generating algorithm for iterative decoding in frequency-hopping spread-spectrum (FH-SS) is proposed. In the algorithm, the channel state probabilities are iteratively calculated with an extension of the Kang-Stark algorithm. Differential encoded phase shift keying (DPSK) is employed with the noncoherent expanded trellis based iterative receiver. The performance of the proposed algorithm with the convolutionally coded system is evaluated by simulation and compared with a system using a ratio threshold test (RTT) for PSK. The results show that the performance of the introduced algorithm is similar to the system with perfect jamming state information and provides better side information than RTT.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"199 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124452428","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371665
H. Yamamoto, T. Yamazato, H. Okada, M. Katayama
We analyze the performance of the multi-carrier CDMA (MC-CDMA) system with and without guard interval (GI) in a two-path channel. From the results, we show that the BER performance in the two cases is almost the same. This implies the removal of GI for the MC-CDMA system.
{"title":"Performance analysis of MC-CDMA system with and without guard interval in two-path channel","authors":"H. Yamamoto, T. Yamazato, H. Okada, M. Katayama","doi":"10.1109/ISSSTA.2004.1371665","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371665","url":null,"abstract":"We analyze the performance of the multi-carrier CDMA (MC-CDMA) system with and without guard interval (GI) in a two-path channel. From the results, we show that the BER performance in the two cases is almost the same. This implies the removal of GI for the MC-CDMA system.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124481231","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371712
K. Adachi, A. Ogawa
We propose a random-access type of packet communications based on a multicarrier spread-spectrum (MC-SS) scheme aimed at being applied to wideband wireless local area networks. Although each user can freely transmit packets, packet losses may not necessarily occur for every collision by virtue of the MC-SS effect. The proposed system is described and the throughput performance of the system is discussed through simulation.
{"title":"Performance characterization for MC-SS packet communications","authors":"K. Adachi, A. Ogawa","doi":"10.1109/ISSSTA.2004.1371712","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371712","url":null,"abstract":"We propose a random-access type of packet communications based on a multicarrier spread-spectrum (MC-SS) scheme aimed at being applied to wideband wireless local area networks. Although each user can freely transmit packets, packet losses may not necessarily occur for every collision by virtue of the MC-SS effect. The proposed system is described and the throughput performance of the system is discussed through simulation.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124752495","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371677
R. Bohnke, V. Kuhn, K. Kammeyer
We propose the use of multistratum space-time codes (MSSTC) for the asynchronous uplink of broadband MIMO-CDMA systems. This transmission scheme, originally proposed for single-user systems and flat fading channels, combines the benefits of both space-time block codes and multilayer transmission, i.e. it exploits transmit diversity and simultaneously enables high data rates with reasonable decoding complexity. Though the full potential of multistratum codes can only be achieved by using adaptive channel coding, we show by simulation results that they are a promising approach even in the uncoded case.
{"title":"Multistratum space-time codes for the asynchronous uplink of MIMO-CDMA systems","authors":"R. Bohnke, V. Kuhn, K. Kammeyer","doi":"10.1109/ISSSTA.2004.1371677","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371677","url":null,"abstract":"We propose the use of multistratum space-time codes (MSSTC) for the asynchronous uplink of broadband MIMO-CDMA systems. This transmission scheme, originally proposed for single-user systems and flat fading channels, combines the benefits of both space-time block codes and multilayer transmission, i.e. it exploits transmit diversity and simultaneously enables high data rates with reasonable decoding complexity. Though the full potential of multistratum codes can only be achieved by using adaptive channel coding, we show by simulation results that they are a promising approach even in the uncoded case.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129526925","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371689
Chia-Horng Liu
We present a simple and robust symbol timing recovery algorithm for OFDM systems, such as IEEE 802.11a/g. The algorithm is derived according to a maximum likelihood (ML) algorithm utilizing the cyclic extension or cyclic prefix (CP), which is appended in front of each OFDM symbol. Simulation results show that the performance of the proposed algorithm is better than the conventional ML algorithm in the additive white Gaussian noise (AWGN) channel and approaches to the ML algorithm in the Rayleigh fading channel. Furthermore, the implementation complexity is lower than that of the ML algorithm.
{"title":"On the design of symbol timing recovery for WLAN OFDM systems","authors":"Chia-Horng Liu","doi":"10.1109/ISSSTA.2004.1371689","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371689","url":null,"abstract":"We present a simple and robust symbol timing recovery algorithm for OFDM systems, such as IEEE 802.11a/g. The algorithm is derived according to a maximum likelihood (ML) algorithm utilizing the cyclic extension or cyclic prefix (CP), which is appended in front of each OFDM symbol. Simulation results show that the performance of the proposed algorithm is better than the conventional ML algorithm in the additive white Gaussian noise (AWGN) channel and approaches to the ML algorithm in the Rayleigh fading channel. Furthermore, the implementation complexity is lower than that of the ML algorithm.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129554434","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 : 2004-08-30DOI: 10.1109/ISSSTA.2004.1371737
B. Mielczarek, W. Krzymień
We present an architecture for a realistic multi-user multi-antenna system operating on a frequency selective fading channel. We argue that it is highly unlikely that the base station has access to full channel state information and we design our system accordingly. By splitting the signal processing burden between the base station and the individual receivers, we take into consideration possible upgrades of the system and likely heterogeneity of the receivers. The proposed system divides the available transmission bandwidth into sub-bands and uses a layered MIMO approach to transmit information to all users, which in turn employ some form of interference cancellation. Based on simulations, we show the influence of different system parameters on upper bounds on the downlink throughput of the system.
{"title":"Throughput of realistic multi-user MIMO-OFDM systems","authors":"B. Mielczarek, W. Krzymień","doi":"10.1109/ISSSTA.2004.1371737","DOIUrl":"https://doi.org/10.1109/ISSSTA.2004.1371737","url":null,"abstract":"We present an architecture for a realistic multi-user multi-antenna system operating on a frequency selective fading channel. We argue that it is highly unlikely that the base station has access to full channel state information and we design our system accordingly. By splitting the signal processing burden between the base station and the individual receivers, we take into consideration possible upgrades of the system and likely heterogeneity of the receivers. The proposed system divides the available transmission bandwidth into sub-bands and uses a layered MIMO approach to transmit information to all users, which in turn employ some form of interference cancellation. Based on simulations, we show the influence of different system parameters on upper bounds on the downlink throughput of the system.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129597438","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 : 2004-08-30DOI: 10.1093/ietcom/e88-b.7.2944
Fang-Biau Ueng, Jun-Da Chen, S. Cheng
Smart antennas, with spatial processing, used in code division multiple access (CDMA) multiuser communications can enhance range, reliability and capacity. Moreover, adaptive beamforming techniques can remove unwanted noise and jamming from the received signal. We use a least mean squares algorithm and propose four adaptive antenna receiver structures for a direct-sequence (DS) CDMA multiuser environment with multipath fading channels. Narrowband and wideband adaptive array receiver structures are considered. LMS algorithms are employed in both narrowband and wideband receiver structures to adjust the spreading code coefficients. We call these new schemes Wiener code filters. The weights of the adaptive beamformer and the spreading code are updated every bit interval, so the computational complexity is very low. Simulation examples are given to compare the performances of the proposed receiver structures.
{"title":"Smart antennas for multiuser DS/CDMA communications in multipath fading channels","authors":"Fang-Biau Ueng, Jun-Da Chen, S. Cheng","doi":"10.1093/ietcom/e88-b.7.2944","DOIUrl":"https://doi.org/10.1093/ietcom/e88-b.7.2944","url":null,"abstract":"Smart antennas, with spatial processing, used in code division multiple access (CDMA) multiuser communications can enhance range, reliability and capacity. Moreover, adaptive beamforming techniques can remove unwanted noise and jamming from the received signal. We use a least mean squares algorithm and propose four adaptive antenna receiver structures for a direct-sequence (DS) CDMA multiuser environment with multipath fading channels. Narrowband and wideband adaptive array receiver structures are considered. LMS algorithms are employed in both narrowband and wideband receiver structures to adjust the spreading code coefficients. We call these new schemes Wiener code filters. The weights of the adaptive beamformer and the spreading code are updated every bit interval, so the computational complexity is very low. Simulation examples are given to compare the performances of the proposed receiver structures.","PeriodicalId":340769,"journal":{"name":"Eighth IEEE International Symposium on Spread Spectrum Techniques and Applications - Programme and Book of Abstracts (IEEE Cat. No.04TH8738)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127543252","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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