Pub Date : 1998-09-02DOI: 10.1109/ISSSTA.1998.723816
K. T. Tan, R. Liyanapathirana, K. Ngan
We present the mathematical formulation of a much forgotten digital multiplexing technique, sequency majority multiplexing (SMM), and outline the error probability derivations for both the SMM and the concatenated sequency majority multiplexing (CSMM) schemes. This work re-traced the steps taken in previous literature and revealed some errors reported in the reviewed papers. This paper sets the scene for the reporting of the numerical analysis on the error performance of both the SMM and CSMM schemes in both the traditional AWGN and in frequency-nonselective, slowly fading channels.
{"title":"Error probabilities for sequency majority multiplexing in frequency-nonselective, slowly fading channels. I. Mathematical formulation","authors":"K. T. Tan, R. Liyanapathirana, K. Ngan","doi":"10.1109/ISSSTA.1998.723816","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.723816","url":null,"abstract":"We present the mathematical formulation of a much forgotten digital multiplexing technique, sequency majority multiplexing (SMM), and outline the error probability derivations for both the SMM and the concatenated sequency majority multiplexing (CSMM) schemes. This work re-traced the steps taken in previous literature and revealed some errors reported in the reviewed papers. This paper sets the scene for the reporting of the numerical analysis on the error performance of both the SMM and CSMM schemes in both the traditional AWGN and in frequency-nonselective, slowly fading channels.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126776788","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.726224
J. Lindner, M. Nold, W. Teich, M. Schreiner
The influence of multiple receiving antennas on the bit error rate is considered for MC-CDMA and OFDMA. It is shown that in a frequency-selective environment reception with a general multiuser/multiantenna receiver the performance of both schemes tend to become similar with an increasing number of antennas. As an example, this is demonstrated for an indoor scenario.
{"title":"MC-CDMA and OFDMA for indoor communications: the influence of multiple receiving antennas","authors":"J. Lindner, M. Nold, W. Teich, M. Schreiner","doi":"10.1109/ISSSTA.1998.726224","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.726224","url":null,"abstract":"The influence of multiple receiving antennas on the bit error rate is considered for MC-CDMA and OFDMA. It is shown that in a frequency-selective environment reception with a general multiuser/multiantenna receiver the performance of both schemes tend to become similar with an increasing number of antennas. As an example, this is demonstrated for an indoor scenario.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123186089","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.726255
G. Berger, H. Safer, F. Seifert
The performance of VHF frequency hopping (FH) radios with different synchronization philosophies is investigated, based on a synthesized channel model which takes into account the spatially inhomogeneous distribution of partial waves. The channel parameters are gained from VHF wideband channel measurements in hilly and mountainous terrain. For the simulation we use a binary phase shift keying (BFSK) modulation and a non-coherent matched filter receiver with a maximum likelihood decision. To keep computation time low, all functional blocks in the communication system are represented in the baseband where the dependence on the carrier frequency is included in the channel model. Due to the multipath propagation, the optimum sampling point at the output of the receiver's matched filter changes for each carrier frequency and for different receiver positions. The simulation results show the difference in the bit error rate (BER) of a slow FH radio system with and without synchronizing each hop.
{"title":"Performance of VHF FH-radios with different bit-synchronization mechanisms in a multipath environment","authors":"G. Berger, H. Safer, F. Seifert","doi":"10.1109/ISSSTA.1998.726255","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.726255","url":null,"abstract":"The performance of VHF frequency hopping (FH) radios with different synchronization philosophies is investigated, based on a synthesized channel model which takes into account the spatially inhomogeneous distribution of partial waves. The channel parameters are gained from VHF wideband channel measurements in hilly and mountainous terrain. For the simulation we use a binary phase shift keying (BFSK) modulation and a non-coherent matched filter receiver with a maximum likelihood decision. To keep computation time low, all functional blocks in the communication system are represented in the baseband where the dependence on the carrier frequency is included in the channel model. Due to the multipath propagation, the optimum sampling point at the output of the receiver's matched filter changes for each carrier frequency and for different receiver positions. The simulation results show the difference in the bit error rate (BER) of a slow FH radio system with and without synchronizing each hop.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"6 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116089746","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.726204
T. Ostman, B. Ottersten, L. Milstein
This article treats the problem of time delay estimation in a multirate asynchronous direct-sequence code-division multiple access (DS-CDMA) system in a near-far scenario. A subspace based algorithm for the time delay estimation problem is proposed. The algorithm is a minor modified version of the MUSIC estimator proposed by Ostman, Parkvall and Ottersten (see Proceedings of the 31st Asilomar Conference on Signals, Systems and Computers, 1997). Through theoretical analysis and simulations it is shown that the subspace approach to time delay estimation in a multirate DS-CDMA system is applicable when the algorithm is applied in a way such that the low-rank structure of the system is conserved.
{"title":"Estimation of time delays in multirate asynchronous DS-CDMA systems","authors":"T. Ostman, B. Ottersten, L. Milstein","doi":"10.1109/ISSSTA.1998.726204","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.726204","url":null,"abstract":"This article treats the problem of time delay estimation in a multirate asynchronous direct-sequence code-division multiple access (DS-CDMA) system in a near-far scenario. A subspace based algorithm for the time delay estimation problem is proposed. The algorithm is a minor modified version of the MUSIC estimator proposed by Ostman, Parkvall and Ottersten (see Proceedings of the 31st Asilomar Conference on Signals, Systems and Computers, 1997). Through theoretical analysis and simulations it is shown that the subspace approach to time delay estimation in a multirate DS-CDMA system is applicable when the algorithm is applied in a way such that the low-rank structure of the system is conserved.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116124352","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.726233
L. Ouvry, C. Boulanger, J. Lequepeys
In any DS-CDMA digital receiver, the first tasks to perform on the baseband analog signal are scaling, sampling and quantization in order to feed a conventional bank of code matched filters or and advanced multiuser detector. However, the performance of the conventional receiver is reduced if the signal has not been properly converted in the digital domain. In this paper, the impact of quantization on the performance of the so-called single user detector is evaluated. The main goal is to be able to foresee the quantization dynamics requirements in any DSSS or DS-CDMA digital receiver.
{"title":"Quantization effects on a DS-CDMA signal","authors":"L. Ouvry, C. Boulanger, J. Lequepeys","doi":"10.1109/ISSSTA.1998.726233","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.726233","url":null,"abstract":"In any DS-CDMA digital receiver, the first tasks to perform on the baseband analog signal are scaling, sampling and quantization in order to feed a conventional bank of code matched filters or and advanced multiuser detector. However, the performance of the conventional receiver is reduced if the signal has not been properly converted in the digital domain. In this paper, the impact of quantization on the performance of the so-called single user detector is evaluated. The main goal is to be able to foresee the quantization dynamics requirements in any DSSS or DS-CDMA digital receiver.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"580 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116205983","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.722525
S. Maric, O. Moreno
We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and that the i-th receiver is only interested in the message transmitted by the i-th transmitter. The degradation of the AWGN and non-selective Rayleigh fading environments on the FH system are also investigated. We then give an algebraic construction of a new family of FH codes. The construction is based on the property of cyclic groups in finite fields; it is shown that for each field GF(p/sup m/) there exists a large number of codes of length p/sup m/. The codes are also shown to possess the best possible two-dimensional auto- and cross-correlation properties.
{"title":"The role of frequency hopping in today's digital communications","authors":"S. Maric, O. Moreno","doi":"10.1109/ISSSTA.1998.722525","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.722525","url":null,"abstract":"We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and that the i-th receiver is only interested in the message transmitted by the i-th transmitter. The degradation of the AWGN and non-selective Rayleigh fading environments on the FH system are also investigated. We then give an algebraic construction of a new family of FH codes. The construction is based on the property of cyclic groups in finite fields; it is shown that for each field GF(p/sup m/) there exists a large number of codes of length p/sup m/. The codes are also shown to possess the best possible two-dimensional auto- and cross-correlation properties.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124901414","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.726184
J. Cilliers, L. Linde, D. van Wyk
This paper describes the implementation of a spectrally efficient 4-dimensional Q/sup 2/PSK (quadrature-quadrature phase shift keying) DSSS modulation strategy. By using Q/sup 2/PSK, combinations of four, two or one data streams can be modulated in parallel in the same bandwidth as normally occupied by a QPSK system. This allows for even greater flexibility in terms of data throughput rate and reliability in accordance with the prevailing channel conditions. The disadvantages of the Q/sup 2/PSK modulation strategy, such as its inherent sensitivity to phase distortion, can be effectively mitigated by employing the multidimensional spreading technique proposed in this paper. Finally, the efficiency of the proposed Q/sup 2/PSK DS-SSMA system is assessed and demonstrated in a multi-user interference (MUI) environment by means of computer simulation. Very promising results is demonstrated with relatively short sequences used in the simulation studies.
{"title":"A synchronous Q/sup 2/PSK DS-CDMA system: system conceptualisation, implementation and performance analysis","authors":"J. Cilliers, L. Linde, D. van Wyk","doi":"10.1109/ISSSTA.1998.726184","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.726184","url":null,"abstract":"This paper describes the implementation of a spectrally efficient 4-dimensional Q/sup 2/PSK (quadrature-quadrature phase shift keying) DSSS modulation strategy. By using Q/sup 2/PSK, combinations of four, two or one data streams can be modulated in parallel in the same bandwidth as normally occupied by a QPSK system. This allows for even greater flexibility in terms of data throughput rate and reliability in accordance with the prevailing channel conditions. The disadvantages of the Q/sup 2/PSK modulation strategy, such as its inherent sensitivity to phase distortion, can be effectively mitigated by employing the multidimensional spreading technique proposed in this paper. Finally, the efficiency of the proposed Q/sup 2/PSK DS-SSMA system is assessed and demonstrated in a multi-user interference (MUI) environment by means of computer simulation. Very promising results is demonstrated with relatively short sequences used in the simulation studies.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121857045","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.722488
Chua Peng Huat
QPSK (quadrature phase shift keying) has been known to be a bandwidth efficient modulation format. The performances of DS-BPSK (direct sequence binary phase shift keying) and DS-QPSK (direct sequence quadrature phase shift keying) modulation formats in a CDMA (code division multiple access) environment are compared in this study to see if this efficiency is preserved under the above conditions. This comparison study includes the effects of bandpass filtering which is not found in current literature. Parameters of interest are the BER (bit error rate) and the capacity supported.
{"title":"Performance comparison of DS-BPSK and DS-QPSK CDMA systems","authors":"Chua Peng Huat","doi":"10.1109/ISSSTA.1998.722488","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.722488","url":null,"abstract":"QPSK (quadrature phase shift keying) has been known to be a bandwidth efficient modulation format. The performances of DS-BPSK (direct sequence binary phase shift keying) and DS-QPSK (direct sequence quadrature phase shift keying) modulation formats in a CDMA (code division multiple access) environment are compared in this study to see if this efficiency is preserved under the above conditions. This comparison study includes the effects of bandpass filtering which is not found in current literature. Parameters of interest are the BER (bit error rate) and the capacity supported.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134532721","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.723812
E. Del Re, R. Fantacci, S. Morosi, S. Marapodi
This paper deals with a multiuser detector for DS-CDMA wireless communication systems. The proposed detector's main feature lies in the joint utilization of the space and time processing techniques since adaptive antenna arrays and decorrelating multiuser receiver are supposed to be used together. Complexity growth is lowered by implementing a multiuser detection technique based on the sliding window algorithm. The DS-CDMA communication system considered resorts to QPSK modulated wideband signals so that a sliding window algorithm generalization is necessary. The simulation results shown here confirm that the proposed structure is near-far resistant even in the worst fading cases. As the sensor number increases a remarkable performance improvement takes place. Besides we show that the proposed receiver allows systems to exploit completely the array introduction while maintaining an acceptable computational complexity.
{"title":"A low-complexity multiuser detector for asynchronous CDMA QPSK systems with adaptive antenna arrays","authors":"E. Del Re, R. Fantacci, S. Morosi, S. Marapodi","doi":"10.1109/ISSSTA.1998.723812","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.723812","url":null,"abstract":"This paper deals with a multiuser detector for DS-CDMA wireless communication systems. The proposed detector's main feature lies in the joint utilization of the space and time processing techniques since adaptive antenna arrays and decorrelating multiuser receiver are supposed to be used together. Complexity growth is lowered by implementing a multiuser detection technique based on the sliding window algorithm. The DS-CDMA communication system considered resorts to QPSK modulated wideband signals so that a sliding window algorithm generalization is necessary. The simulation results shown here confirm that the proposed structure is near-far resistant even in the worst fading cases. As the sensor number increases a remarkable performance improvement takes place. Besides we show that the proposed receiver allows systems to exploit completely the array introduction while maintaining an acceptable computational complexity.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122922293","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 : 1998-09-02DOI: 10.1109/ISSSTA.1998.723866
R. Tanner, D. Cruickshank
This paper presents a Mahalanobis based radial basis function network (RBF) receiver structure with reduced complexity. It is also illustrated, how the RBF receiver could be employed as a multiuser detector. The RBF structure has superior performance over linear receiver structures and is equivalent to MLSD in an AWGN channel. However, a drawback is its complexity in multipath channels. Ideas from pattern recognition are exploited to reduce its complexity for multipath scenarios with little performance loss.
{"title":"RBF based receivers for DS-CDMA with reduced complexity","authors":"R. Tanner, D. Cruickshank","doi":"10.1109/ISSSTA.1998.723866","DOIUrl":"https://doi.org/10.1109/ISSSTA.1998.723866","url":null,"abstract":"This paper presents a Mahalanobis based radial basis function network (RBF) receiver structure with reduced complexity. It is also illustrated, how the RBF receiver could be employed as a multiuser detector. The RBF structure has superior performance over linear receiver structures and is equivalent to MLSD in an AWGN channel. However, a drawback is its complexity in multipath channels. Ideas from pattern recognition are exploited to reduce its complexity for multipath scenarios with little performance loss.","PeriodicalId":116377,"journal":{"name":"1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333)","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132167379","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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