Pub Date : 1990-05-06DOI: 10.1109/VETEC.1990.110293
J. Cavers
An adaptive predistorter particularly suited to baseband implementation with digital signal-processing hardware is presented and analyzed. It is applicable to any modulation format and any AM/FM and FM/PM characteristic. With a table of well under 100 complex words, it reduces intermodulation products in a typical Class AB amplifier to levels suitable for the mobile environment. It adapts to a new amplifier in a few milliseconds, and its reconvergence time following a channel switch is virtually zero. Since it allows linearization of the power amplifier over 95% to 98% of the saturated output power, it provides power efficiency as well. In comparison with the most powerful predistorter previously reported, it requires four orders of magnitude less memory, reduces convergence time by over three orders of magnitude, eliminates reconvergence time following a channel switch, and eliminates the need for a phase shifter in the feedback path.<>
{"title":"A linearizing predistorter with fast adaptation","authors":"J. Cavers","doi":"10.1109/VETEC.1990.110293","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110293","url":null,"abstract":"An adaptive predistorter particularly suited to baseband implementation with digital signal-processing hardware is presented and analyzed. It is applicable to any modulation format and any AM/FM and FM/PM characteristic. With a table of well under 100 complex words, it reduces intermodulation products in a typical Class AB amplifier to levels suitable for the mobile environment. It adapts to a new amplifier in a few milliseconds, and its reconvergence time following a channel switch is virtually zero. Since it allows linearization of the power amplifier over 95% to 98% of the saturated output power, it provides power efficiency as well. In comparison with the most powerful predistorter previously reported, it requires four orders of magnitude less memory, reduces convergence time by over three orders of magnitude, eliminates reconvergence time following a channel switch, and eliminates the need for a phase shifter in the feedback path.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131930294","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110312
F. Thatcher
Design techniques used to satisfy underground radio communications requirements are discussed. The topics include operational requirements and functional design, propagation characteristics in the subsurface areas, test arrangement, test procedure and data, and analysis of the test data. The application discussed in typical of many industrial facilities where cost and performance are important considerations. A major portion of the study is dedicated to tests conducted to select the most practical radiating element used for the distributed antennas.<>
{"title":"Design of a subsurface radio communications systems using several types of distributed radiators","authors":"F. Thatcher","doi":"10.1109/VETEC.1990.110312","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110312","url":null,"abstract":"Design techniques used to satisfy underground radio communications requirements are discussed. The topics include operational requirements and functional design, propagation characteristics in the subsurface areas, test arrangement, test procedure and data, and analysis of the test data. The application discussed in typical of many industrial facilities where cost and performance are important considerations. A major portion of the study is dedicated to tests conducted to select the most practical radiating element used for the distributed antennas.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133874626","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110406
S. Taira, T. Ikegami, R. Suzuki, S. Suzuki, H. Kawahara, S. Kawase, Shun-Ichi Tada
The performance of a land mobile earth station using the amplitude companded single sideband (ACSSB) modulation technique, and results of field experiments which were conducted at L-band (1.6/1.5 GHz) in a static environment and in rural, suburban, and urban areas, are described. Results of the experiments show that the required carrier to noise power density ratio (C/No) for voice communications is greater than 40 dBHz and the required C/No for pilot signal tracking is 34 dBHz. A comparison of the ACSSB system with the conventional narrowband frequency modulation (NBFM) system is also carried out. The analysis of the power spectral density indicates that the ACSSB system is four times as efficient as the NBFM system.<>
{"title":"Experiments on ACSSB land mobile satellite communications","authors":"S. Taira, T. Ikegami, R. Suzuki, S. Suzuki, H. Kawahara, S. Kawase, Shun-Ichi Tada","doi":"10.1109/VETEC.1990.110406","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110406","url":null,"abstract":"The performance of a land mobile earth station using the amplitude companded single sideband (ACSSB) modulation technique, and results of field experiments which were conducted at L-band (1.6/1.5 GHz) in a static environment and in rural, suburban, and urban areas, are described. Results of the experiments show that the required carrier to noise power density ratio (C/No) for voice communications is greater than 40 dBHz and the required C/No for pilot signal tracking is 34 dBHz. A comparison of the ACSSB system with the conventional narrowband frequency modulation (NBFM) system is also carried out. The analysis of the power spectral density indicates that the ACSSB system is four times as efficient as the NBFM system.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130325550","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110333
S. Chia, R. Warburton
1700 MHz attenuation and bit error rate (BER) measurements were conducted at the center of a major urban area in southern England in order to compile a radio propagation and BER database for handover criteria study in city microcellular radio systems. The focus of the experiments was to provide realistic data for handover simulation in typical city microcell environments, thus minimizing inaccuracies due to the inadequacies in propagation modeling. Results revealed the path loss followed the inverse third to fourth power law in majority of the cases using simple regression fitting. The short-term signal fading statistics varied with Rice factors in excess of ten down to zero, as the distance between the mobile unit and the microcellular base station increased. Computer simulation indicated that both RSSI (received signal strength indicator) and BER could be used as handover criteria. The optimal threshold level for handover request, however, differed from location to location.<>
{"title":"Handover criteria for city microcellular radio systems","authors":"S. Chia, R. Warburton","doi":"10.1109/VETEC.1990.110333","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110333","url":null,"abstract":"1700 MHz attenuation and bit error rate (BER) measurements were conducted at the center of a major urban area in southern England in order to compile a radio propagation and BER database for handover criteria study in city microcellular radio systems. The focus of the experiments was to provide realistic data for handover simulation in typical city microcell environments, thus minimizing inaccuracies due to the inadequacies in propagation modeling. Results revealed the path loss followed the inverse third to fourth power law in majority of the cases using simple regression fitting. The short-term signal fading statistics varied with Rice factors in excess of ten down to zero, as the distance between the mobile unit and the microcellular base station increased. Computer simulation indicated that both RSSI (received signal strength indicator) and BER could be used as handover criteria. The optimal threshold level for handover request, however, differed from location to location.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132585540","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110380
F. Lotse, A. Wejke
Propagation measurements were made for microcells implemented using low omnidirectional antennas. 20 sites in a flat, homogeneous area of Stockholm were used. The transmitting antennas and the mobile receiving antenna were 5 m and 2 m in height, respectively. Each base station transmitted at a unique frequency in the vicinity of 870 MHz. The radio wave propagation along streets and around corners is studied. On a log-log scale, the signal decreases faster as a function of distance from the antenna when the mobile is far away from the antenna than when it is close. The signal loss suffered when turning a corner from a LOS (line-of-sight) onto a NLOS (non-line-of-sight) street is 20-25 dB. The rate of signal decrease near a corner is very sensitive to the type of LOS street and can be very high, requiring efficient handover procedures.<>
{"title":"Propagation measurements for microcells in central Stockholm","authors":"F. Lotse, A. Wejke","doi":"10.1109/VETEC.1990.110380","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110380","url":null,"abstract":"Propagation measurements were made for microcells implemented using low omnidirectional antennas. 20 sites in a flat, homogeneous area of Stockholm were used. The transmitting antennas and the mobile receiving antenna were 5 m and 2 m in height, respectively. Each base station transmitted at a unique frequency in the vicinity of 870 MHz. The radio wave propagation along streets and around corners is studied. On a log-log scale, the signal decreases faster as a function of distance from the antenna when the mobile is far away from the antenna than when it is close. The signal loss suffered when turning a corner from a LOS (line-of-sight) onto a NLOS (non-line-of-sight) street is 20-25 dB. The rate of signal decrease near a corner is very sensitive to the type of LOS street and can be very high, requiring efficient handover procedures.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114255923","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110393
N. Sollenberger
In time-division multiple access (TDMA) radio systems, the on/off power transitions at burst boundaries must be carefully controlled to minimize spectral spreading while also minimizing transition times. Several methods of performing power transitions are examined. The first method uses a continuous modulator which is windowed with a raised cosine. The second method uses the addition of individual signaling pulses as a part of the modulator circuit. This method causes no excess spectral spreading from the on/off power transitions. A third method uses asymmetric pulse shapes during the transition times to minimize the transition times, while causing no excess spectral spreading. The design of these pulses and circuits to generate them are discussed. Since the circuit is completely digital with low complexity, it is suitable for VLSI implementation.<>
{"title":"Pulse design and efficient generation circuits for linear TDMA modulation","authors":"N. Sollenberger","doi":"10.1109/VETEC.1990.110393","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110393","url":null,"abstract":"In time-division multiple access (TDMA) radio systems, the on/off power transitions at burst boundaries must be carefully controlled to minimize spectral spreading while also minimizing transition times. Several methods of performing power transitions are examined. The first method uses a continuous modulator which is windowed with a raised cosine. The second method uses the addition of individual signaling pulses as a part of the modulator circuit. This method causes no excess spectral spreading from the on/off power transitions. A third method uses asymmetric pulse shapes during the transition times to minimize the transition times, while causing no excess spectral spreading. The design of these pulses and circuits to generate them are discussed. Since the circuit is completely digital with low complexity, it is suitable for VLSI implementation.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127734700","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110411
G. Yang, P. Ho, V. Cuperman
An error protection scheme for a vector-quantization (VQ)-based code excited linear predictive (CELP) coder for mobile radio applications is proposed. To arrive at an appropriate error protection strategy, the sensitivity of the different parameters in the CELP coder are studied, and then unequal error protection is designed according to parameter sensitivities. Different levels of error protection are provided by the use of punctured convolutional codes. The mobile radio channel is modeled as a Rayleigh fading channel. A convolutional interleaving technique is used to combat fading. The combined source and channel codec for this application has a total bit rate of 6.4 kb/s, of which 1.6 kb/s is used for channel coding. Simulation result show that the resulting codec can provide good quality speech at a Doppler frequency of 48 Hz and a channel bit error rate as high as 10/sup -2/.<>
{"title":"Error protection for a 4.8 kbps VQ based CELP coder","authors":"G. Yang, P. Ho, V. Cuperman","doi":"10.1109/VETEC.1990.110411","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110411","url":null,"abstract":"An error protection scheme for a vector-quantization (VQ)-based code excited linear predictive (CELP) coder for mobile radio applications is proposed. To arrive at an appropriate error protection strategy, the sensitivity of the different parameters in the CELP coder are studied, and then unequal error protection is designed according to parameter sensitivities. Different levels of error protection are provided by the use of punctured convolutional codes. The mobile radio channel is modeled as a Rayleigh fading channel. A convolutional interleaving technique is used to combat fading. The combined source and channel codec for this application has a total bit rate of 6.4 kb/s, of which 1.6 kb/s is used for channel coding. Simulation result show that the resulting codec can provide good quality speech at a Doppler frequency of 48 Hz and a channel bit error rate as high as 10/sup -2/.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129638052","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110409
V. Leung
A complete set of access protocols for multiple satellite channels assigned for communications between mobile data terminals and fixed data hubs is proposed. The protocols address three types of data bearer services suitable for all types of applications. Multiple access for inbound interactive messages is based on contention for short messages and reservation for longer messages. An overview of the mobile satellite system (MSS) network configuration is given. Traffic characteristics and network connectivity for mobile data services are reviewed. The design of a complete set of multiple access protocols for different data services is described. The proposed protocols are simple to implement, and potentially provide efficient and timely access for both short and long messages.<>
{"title":"Multichannel access protocol for satellite mobile data services","authors":"V. Leung","doi":"10.1109/VETEC.1990.110409","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110409","url":null,"abstract":"A complete set of access protocols for multiple satellite channels assigned for communications between mobile data terminals and fixed data hubs is proposed. The protocols address three types of data bearer services suitable for all types of applications. Multiple access for inbound interactive messages is based on contention for short messages and reservation for longer messages. An overview of the mobile satellite system (MSS) network configuration is given. Traffic characteristics and network connectivity for mobile data services are reviewed. The design of a complete set of multiple access protocols for different data services is described. The proposed protocols are simple to implement, and potentially provide efficient and timely access for both short and long messages.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122955094","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110410
E. Flath
Proving that a system performs as specified, proof-of-performance testing, presents a series of problems. Two different approaches to providing for proof-of-performance (POP) testing are discussed. It is shown that the required system gain can be reduced based on the conditions placed on the POP. The principal problem in the mobile communication systems is the occurrence of large areas with little or no signals in the desired covered area. One method of testing would be to allow one test at a single point. If the test fails, tests would be made at the corners of a box around the point, etc. In this manner, the size of the hole in the coverage area could be determined, and the necessary action taken.<>
{"title":"Proof-of-performance testing","authors":"E. Flath","doi":"10.1109/VETEC.1990.110410","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110410","url":null,"abstract":"Proving that a system performs as specified, proof-of-performance testing, presents a series of problems. Two different approaches to providing for proof-of-performance (POP) testing are discussed. It is shown that the required system gain can be reduced based on the conditions placed on the POP. The principal problem in the mobile communication systems is the occurrence of large areas with little or no signals in the desired covered area. One method of testing would be to allow one test at a single point. If the test fails, tests would be made at the corners of a box around the point, etc. In this manner, the size of the hole in the coverage area could be determined, and the necessary action taken.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124717911","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 : 1990-05-06DOI: 10.1109/VETEC.1990.110396
K. Sivarajan, R. McEliece, J. W. Ketchum
Dynamic channel assignment algorithms for cellular systems are developed. The algorithms are compared with an easily simulated bound. Using this bound, it is demonstrated that in the case of homogeneous spatial traffic distribution, some of these algorithms are virtually unbeatable by any channel assignment algorithm. These algorithms are shown to be feasible for implementation in current cellular systems. For the examples considered, in the interesting range of blocking probabilities (2-4%), the dynamic channel assignment algorithms yielded an increase of 60-80% in the carried traffic over the best-known fixed channel assignment.<>
{"title":"Dynamic channel assignment in cellular radio","authors":"K. Sivarajan, R. McEliece, J. W. Ketchum","doi":"10.1109/VETEC.1990.110396","DOIUrl":"https://doi.org/10.1109/VETEC.1990.110396","url":null,"abstract":"Dynamic channel assignment algorithms for cellular systems are developed. The algorithms are compared with an easily simulated bound. Using this bound, it is demonstrated that in the case of homogeneous spatial traffic distribution, some of these algorithms are virtually unbeatable by any channel assignment algorithm. These algorithms are shown to be feasible for implementation in current cellular systems. For the examples considered, in the interesting range of blocking probabilities (2-4%), the dynamic channel assignment algorithms yielded an increase of 60-80% in the carried traffic over the best-known fixed channel assignment.<<ETX>>","PeriodicalId":366352,"journal":{"name":"40th IEEE Conference on Vehicular Technology","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122888202","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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