Pub Date : 1996-10-15DOI: 10.1109/PIMRC.1996.567486
Y. Lien, C. Leng
In a mobile computing environment that supports mobile agents, a client can send an agent to visit a sequence of servers in the network. To track the location of agents becomes a critical problem in managing a mobile agent service network. This paper studies the agent search problem based on an open architecture proposed by Lien (see Proc. of the First Workshop on Mobile Computing, Hsing-Chu, Taiwan, p.2-9, 1995) and is currently being implemented in the National Chengchi University.
{"title":"On the search of mobile agents","authors":"Y. Lien, C. Leng","doi":"10.1109/PIMRC.1996.567486","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.567486","url":null,"abstract":"In a mobile computing environment that supports mobile agents, a client can send an agent to visit a sequence of servers in the network. To track the location of agents becomes a critical problem in managing a mobile agent service network. This paper studies the agent search problem based on an open architecture proposed by Lien (see Proc. of the First Workshop on Mobile Computing, Hsing-Chu, Taiwan, p.2-9, 1995) and is currently being implemented in the National Chengchi University.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123479843","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.568451
M. Reinhardt, T. Huschka, J. Lindner
We describe a power and bandwidth efficient transmission scheme for Rayleigh fading channels and a suitable low complexity combined equalization and decoding system. The transmission system is based on an orthonormal transform (fast Hadamard transform) combined with trellis-coded modulation (TCM). The receiver uses an iterative block decision feedback equalizer and a Viterbi algorithm to decode the TCM. It is shown that the equalizer transforms the Rayleigh fading channel asymptotically into a set of parallel AWGN subchannels. Therefore, the decoder of each subchannel "sees" an AWGN channel. Hence, coding gains comparable to the coding gains in an AWGN environment can be achieved. The results are considerably better than the performance of TCM codes designed for the Rayleigh fading channel with the same power and bandwidth efficiency. The conclusions of channel capacity considerations support the potential of the proposed transmission and reception scheme. The theoretical findings are furthermore supported by simulation results.
{"title":"Performance of combined equalization and TCM decoding for Rayleigh fading channels","authors":"M. Reinhardt, T. Huschka, J. Lindner","doi":"10.1109/PIMRC.1996.568451","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.568451","url":null,"abstract":"We describe a power and bandwidth efficient transmission scheme for Rayleigh fading channels and a suitable low complexity combined equalization and decoding system. The transmission system is based on an orthonormal transform (fast Hadamard transform) combined with trellis-coded modulation (TCM). The receiver uses an iterative block decision feedback equalizer and a Viterbi algorithm to decode the TCM. It is shown that the equalizer transforms the Rayleigh fading channel asymptotically into a set of parallel AWGN subchannels. Therefore, the decoder of each subchannel \"sees\" an AWGN channel. Hence, coding gains comparable to the coding gains in an AWGN environment can be achieved. The results are considerably better than the performance of TCM codes designed for the Rayleigh fading channel with the same power and bandwidth efficiency. The conclusions of channel capacity considerations support the potential of the proposed transmission and reception scheme. The theoretical findings are furthermore supported by simulation results.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127124201","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.567397
F. Tong, T. Otani, Y. Akaiwa
In the multipath mobile channel, the received signal is affected by both flat fading and selective fading. Using an adaptive array is an effective method to compensate for selective fading, whereas a diversity antenna is good at compensating for flat fading. In this paper, a switching adaptive/diversity antenna is presented and examined with computer simulation. For evaluating the signal whose quality falls repeatedly within a short duration, the probability of DUR (desired to undesired signal ratio) below a given value is adopted. The computer simulation results show that the proposed switching adaptive/diversity antenna can compensate for both flat fading and selective fading.
{"title":"A switching CMA/diversity antenna for canceling echoes with fading in an FM broadcasting receiver","authors":"F. Tong, T. Otani, Y. Akaiwa","doi":"10.1109/PIMRC.1996.567397","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.567397","url":null,"abstract":"In the multipath mobile channel, the received signal is affected by both flat fading and selective fading. Using an adaptive array is an effective method to compensate for selective fading, whereas a diversity antenna is good at compensating for flat fading. In this paper, a switching adaptive/diversity antenna is presented and examined with computer simulation. For evaluating the signal whose quality falls repeatedly within a short duration, the probability of DUR (desired to undesired signal ratio) below a given value is adopted. The computer simulation results show that the proposed switching adaptive/diversity antenna can compensate for both flat fading and selective fading.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128912397","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.568458
V. Cheng, W. Stark
The performance of different coding schemes for direct-sequence spread-spectrum (DS-SS) with multiple-access (MA) interference in a nonselective Rayleigh fading channel is considered. A conventional 64-ary orthogonal code (M/sub 64/) transmitting 6 bits of information is examined first. Each of the 64 code symbols in the M/sub 64/ code is assumed to be spread by a random sequence of length N, and the channel is assumed to be interleaved every N chips. We consider a M/sub 64/ DS-SS code concatenated with a (63, k) Reed-Solomon (RS) outer code and varying the amount of spreading and the code rate for a fixed data rate and bandwidth. Our analysis based on Gaussian approximation shows that when the number of users is reasonably large, an optimal value k* to achieve the minimum bit error probability of the (63, k) RS code can be found. Furthermore, we extend the results by substituting the M/sub 64/ code with the trellis coded Nordstrom-Robinson code (TCNR), and the trellis coded Reed-Muller code (TCRM), which have the same data rate as that of the M/sub 64/ code. An optimal value k* to achieve minimum bit error probability can also be found when the TCNR code or the TCRM code is concatenated with a (63, k) RS outer code.
{"title":"Performance of trellis coded direct-sequence spread-spectrum: multiple-access with noncoherent reception in a fading environment","authors":"V. Cheng, W. Stark","doi":"10.1109/PIMRC.1996.568458","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.568458","url":null,"abstract":"The performance of different coding schemes for direct-sequence spread-spectrum (DS-SS) with multiple-access (MA) interference in a nonselective Rayleigh fading channel is considered. A conventional 64-ary orthogonal code (M/sub 64/) transmitting 6 bits of information is examined first. Each of the 64 code symbols in the M/sub 64/ code is assumed to be spread by a random sequence of length N, and the channel is assumed to be interleaved every N chips. We consider a M/sub 64/ DS-SS code concatenated with a (63, k) Reed-Solomon (RS) outer code and varying the amount of spreading and the code rate for a fixed data rate and bandwidth. Our analysis based on Gaussian approximation shows that when the number of users is reasonably large, an optimal value k* to achieve the minimum bit error probability of the (63, k) RS code can be found. Furthermore, we extend the results by substituting the M/sub 64/ code with the trellis coded Nordstrom-Robinson code (TCNR), and the trellis coded Reed-Muller code (TCRM), which have the same data rate as that of the M/sub 64/ code. An optimal value k* to achieve minimum bit error probability can also be found when the TCNR code or the TCRM code is concatenated with a (63, k) RS outer code.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131049197","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.567462
G. Woodward, P. Rapajic, B. Vucetic
Issues relating to the choice of adaptive algorithms for use in single user minimum mean square error (MMSE) direct sequence (DS) code division multiple access (CDMA) receivers are discussed. Such receivers have the potential to dramatically increase capacity of CDMA systems compared to systems with conventional correlator receivers, without the high complexity associated with many proposed multi-user receivers. To be practical for many applications, the convergence rate of the adaptive algorithms must be improved, while maintaining low residual mean-squared error (MSE), robustness to noise and realisable complexity. The slow convergence of the least mean squares (LMS) algorithm is highlighted for this application. Recursive least squares (RLS) algorithms are shown to give much quicker convergence, but have much higher sensitivity to thermal noise. Algorithms normally termed "Fast-RLS", are shown to more complex than the conventional RLS algorithm when used in a CDMA receiver.
{"title":"Adaptive algorithms for asynchronous DS-CDMA receivers","authors":"G. Woodward, P. Rapajic, B. Vucetic","doi":"10.1109/PIMRC.1996.567462","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.567462","url":null,"abstract":"Issues relating to the choice of adaptive algorithms for use in single user minimum mean square error (MMSE) direct sequence (DS) code division multiple access (CDMA) receivers are discussed. Such receivers have the potential to dramatically increase capacity of CDMA systems compared to systems with conventional correlator receivers, without the high complexity associated with many proposed multi-user receivers. To be practical for many applications, the convergence rate of the adaptive algorithms must be improved, while maintaining low residual mean-squared error (MSE), robustness to noise and realisable complexity. The slow convergence of the least mean squares (LMS) algorithm is highlighted for this application. Recursive least squares (RLS) algorithms are shown to give much quicker convergence, but have much higher sensitivity to thermal noise. Algorithms normally termed \"Fast-RLS\", are shown to more complex than the conventional RLS algorithm when used in a CDMA receiver.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132523855","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.568417
H. Sato, M. Umehira
Wireless ATM (asynchronous transfer mode) is used to provide nomadic and seamless access to ATM based networks. Wireless ATM can offer multiple connections supporting various types of services. For CBR (constant bit rate) and VBR (variable bit rate) services, time-sensitive QoS (quality of services) are important, unlike other services such as ABR (available bit rate). For CBR and VBR services, the peak bandwidth needs to be assigned to meet CDV (cell delay variation) requirements. For time-insensitive services, assigning the peak bandwidth wastes radio resources since the average bandwidth of such services is generally much lower than the peak bandwidth. This paper proposes a QoS oriented buffer control algorithm to satisfy CDV requirements while maximizing radio resource utilization. The proposed scheme needs less total bandwidth than the sum of the peak bandwidths required for all connections.
{"title":"A novel buffer control scheme for ATM cell transport with improved cell delay variation for wireless ATM","authors":"H. Sato, M. Umehira","doi":"10.1109/PIMRC.1996.568417","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.568417","url":null,"abstract":"Wireless ATM (asynchronous transfer mode) is used to provide nomadic and seamless access to ATM based networks. Wireless ATM can offer multiple connections supporting various types of services. For CBR (constant bit rate) and VBR (variable bit rate) services, time-sensitive QoS (quality of services) are important, unlike other services such as ABR (available bit rate). For CBR and VBR services, the peak bandwidth needs to be assigned to meet CDV (cell delay variation) requirements. For time-insensitive services, assigning the peak bandwidth wastes radio resources since the average bandwidth of such services is generally much lower than the peak bandwidth. This paper proposes a QoS oriented buffer control algorithm to satisfy CDV requirements while maximizing radio resource utilization. The proposed scheme needs less total bandwidth than the sum of the peak bandwidths required for all connections.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"43 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132974641","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.567413
H. Lau, S. Cheung
The paper studies the bit-error-rate (BER) performance of a fade-compensated 16 QAM with two-branch postdetection selection combining diversity reception in the Rayleigh fading channels. A pilot symbol-aided (PSA) technique that uses both pilot symbols and data symbols is employed for fading compensation. Computer simulation results have shown that, the use of diversity reception technique can significantly improve the BER performance when the normalized delay between the signals at the two receivers is small. It is also shown that, the error-floor is sensitive to the normalized delay, but relatively less sensitive to the power ratio between the signals at the two receivers.
{"title":"Performance of a fade-compensated 16 QAM with diversity reception in mobile radio channels","authors":"H. Lau, S. Cheung","doi":"10.1109/PIMRC.1996.567413","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.567413","url":null,"abstract":"The paper studies the bit-error-rate (BER) performance of a fade-compensated 16 QAM with two-branch postdetection selection combining diversity reception in the Rayleigh fading channels. A pilot symbol-aided (PSA) technique that uses both pilot symbols and data symbols is employed for fading compensation. Computer simulation results have shown that, the use of diversity reception technique can significantly improve the BER performance when the normalized delay between the signals at the two receivers is small. It is also shown that, the error-floor is sensitive to the normalized delay, but relatively less sensitive to the power ratio between the signals at the two receivers.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132103861","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.567495
A. Molisch, E. Bonek
We give an overview of the work of COST 231 on the "error floor", i.e. errors introduced by the time dispersion of the mobile radio channel. The error floor depends mainly on the RMS delay spread S and on the sampling scheme; the error probability is in general K/spl middot/(S/T)/sup 2/, where T is the bit length. For fixed sampling, the proportionality constant K is about 0.5, and depends only weakly on the filters. For adaptive sampling, K is one or more orders of magnitude smaller, depending strongly on the filters in the system. Errors occur in a "bursty" way in the fading dips.
{"title":"Error floor in cordless communications systems-an overview of the work in COST 231","authors":"A. Molisch, E. Bonek","doi":"10.1109/PIMRC.1996.567495","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.567495","url":null,"abstract":"We give an overview of the work of COST 231 on the \"error floor\", i.e. errors introduced by the time dispersion of the mobile radio channel. The error floor depends mainly on the RMS delay spread S and on the sampling scheme; the error probability is in general K/spl middot/(S/T)/sup 2/, where T is the bit length. For fixed sampling, the proportionality constant K is about 0.5, and depends only weakly on the filters. For adaptive sampling, K is one or more orders of magnitude smaller, depending strongly on the filters in the system. Errors occur in a \"bursty\" way in the fading dips.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130912200","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.568489
P. Mogensen, J. Wigard
This paper analyze the performance of two branch antenna diversity in GSM related systems. Several combining techniques for both up- and downlink are analyzed. Frequency diversity obtained from slow frequency hopping in GSM is also considered. Finally antenna diversity results for a non-ideal antenna configuration, i.e., introducing antenna branch cross-correlation or cross polarization discrimination (XPD) are presented.
{"title":"On antenna- and frequency diversity in GSM related systems (GSM-900, DCS-1800, and PCS1900)","authors":"P. Mogensen, J. Wigard","doi":"10.1109/PIMRC.1996.568489","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.568489","url":null,"abstract":"This paper analyze the performance of two branch antenna diversity in GSM related systems. Several combining techniques for both up- and downlink are analyzed. Frequency diversity obtained from slow frequency hopping in GSM is also considered. Finally antenna diversity results for a non-ideal antenna configuration, i.e., introducing antenna branch cross-correlation or cross polarization discrimination (XPD) are presented.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131324312","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 : 1996-10-15DOI: 10.1109/PIMRC.1996.567441
M. Lee, Ju Yong Park, Myong Won Kwon, Seung-Rae Lee
The class of reverse jacket matrices (~RJ/sub N/) is defined; the main property of ~RJ/sub N/ is that the inverse matrices of its elements can be obtained very easily and have a recursive structure. ~RJ/sub N/ is a generalized form of the weighted Hadamard transform. Each element of ~RJ/sub N/ can be used to the subsampling matrix. These matrices can be further used to develop efficient algorithms in PCS signal processing as well as in coding and information theory.
{"title":"The reverse jacket matrix of weighted Hadamard transform for multidimensional signal processing","authors":"M. Lee, Ju Yong Park, Myong Won Kwon, Seung-Rae Lee","doi":"10.1109/PIMRC.1996.567441","DOIUrl":"https://doi.org/10.1109/PIMRC.1996.567441","url":null,"abstract":"The class of reverse jacket matrices (~RJ/sub N/) is defined; the main property of ~RJ/sub N/ is that the inverse matrices of its elements can be obtained very easily and have a recursive structure. ~RJ/sub N/ is a generalized form of the weighted Hadamard transform. Each element of ~RJ/sub N/ can be used to the subsampling matrix. These matrices can be further used to develop efficient algorithms in PCS signal processing as well as in coding and information theory.","PeriodicalId":206655,"journal":{"name":"Proceedings of PIMRC '96 - 7th International Symposium on Personal, Indoor, and Mobile Communications","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129191406","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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