{"title":"Performance analysis of synchronization errors on digital adaptive beamforming for a high bit-rate QAM receiver","authors":"Jind-Yeh Lee, Huan-Chang Liu, H. Samueli","doi":"10.1109/VETEC.1997.600493","DOIUrl":"https://doi.org/10.1109/VETEC.1997.600493","url":null,"abstract":"Digital adaptive beamforming (ABF), with its ability to enhance frequency reuse and co-channel-interference rejection for improved service capacity and link quality, is expected to play an important role in future wireless communications. However, the performance of such a digital communication system strongly relies on the accuracy of synchronization. This paper investigates the system performance of digital adaptive beamforming in a digital QAM receiver in the presence of synchronization errors. The simulation results show that digital adaptive beamforming can cancel interference while simultaneously compensate for the carrier phase and frequency offset to support a reliable 64-QAM link. However, this system is very sensitive to the symbol timing error and the sampling timing offset. The system employing both ABF and adaptive equalization, which can reject interference in a multipath environment, is able to compensate for the symbol timing error and the sampling timing offset. The tracking range of the carrier frequency offset is also improved in the system with both adaptive beamforming and equalization.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122138036","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}
J. Casademont, J. Paradells, S. Sallent, J. Oriol, J. Ferrer, J. J. Banuls
{"title":"Distributed antenna in the radio local loop based on DECT","authors":"J. Casademont, J. Paradells, S. Sallent, J. Oriol, J. Ferrer, J. J. Banuls","doi":"10.1109/VETEC.1997.600519","DOIUrl":"https://doi.org/10.1109/VETEC.1997.600519","url":null,"abstract":"The Digital European Cordless Telecommunication System (DECT) is gaining acceptance in environments different to the ones the system has been designed for. In particular in the radio local loop (RLL) and in personal communication services (PCS) applications. The main difference between indoors, where DECT was supposed to work, and outdoors is that in this latter environment the signal propagation is not limited between walls. The first result of this environment is the capacity limitation of the DECT base station (BS) due to interference. To increase the DECT system's capacity it is possible to use directional antennas in the BS and in the user terminal. Even using interference reduction techniques most of the blocked or interrupted calls are due to the co-channel interference, so the traffic capacity per BS is low compared to the amount of channels per base station. In this paper we show that it is possible to share BS equipment between several cells, increasing the usage of radio fixed part resources without reducing traffic capacity. From the interference point of view the capacity of those split BS is identical to the former solution but thanks to the shared use of several antennas the efficiency is higher.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116601567","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}
{"title":"Performance improvement in GSM networks due to slow frequency hopping","authors":"G. Tunnicliffe, A. Sathyendran, A. Murch","doi":"10.1109/VETEC.1997.605880","DOIUrl":"https://doi.org/10.1109/VETEC.1997.605880","url":null,"abstract":"This paper investigates the performance of GSM systems employing slow frequency hopping when a limited number of hopping channels are used. Frequency hopping increases spectral efficiency by enabling frequencies to be reused more intensely. Previous analysis of frequency hopping systems have considered systems that have a large number of hopping channels available. However, due to spectrum and frequency planning constraints, there are often only a limited number of channels available for hopping in most cellular systems and consequently maximum improvement cannot be achieved. The performance of such a system is evaluated and a comparison made between frequency hopping and intra-timeslot handover. Intra-timeslot handover is found to have better interference immunity performance than two channel frequency hopping when the mean C/I is less than approximately 16 dB in both the urban and suburban environments. The results show that the performance of frequency hopping surpasses that of intra-timeslot handover as more hopping channels are deployed.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129561075","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}
{"title":"A study on a channel allocation scheme with an adaptive array in SDMA","authors":"T. Ohgane, Y. Ogawa, K. Itoh","doi":"10.1109/VETEC.1997.600424","DOIUrl":"https://doi.org/10.1109/VETEC.1997.600424","url":null,"abstract":"This paper describes spatial division multiple access (SDMA) using an adaptive array. A spatial correlation coefficient is proposed as a criterion to determine the possibility of duplicate channel allocation. When the average input SNR is more than 20 dB, the users satisfying a correlation coefficient of less than 0.9 can be accommodated in the same channel in a 2-user SDMA model with a 2-element adaptive array. The blocking rate performance shows that this 2-user SDMA can improve channel efficiency almost twice.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129574280","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}
{"title":"Traffic performance and mobility modeling of cellular communications with mixed platforms and highly variable mobilities","authors":"P. Orlik, S. Rappaport","doi":"10.1109/VETEC.1997.600396","DOIUrl":"https://doi.org/10.1109/VETEC.1997.600396","url":null,"abstract":"In modeling teletraffic performance of mobile cellular networks some characteristic mobilities are assumed to be known. It is useful if these assumptions impose few restrictions and lead to analytically tractable models. We present a new probability density function where the coefficient of variation can be larger than one but which nevertheless lends itself to analytical modeling using memoryless properties and multi-dimensional birth-death processes. This extends the previous framework to a broader class of mobilities. The approach allows computation of major teletraffic performance characteristics for cellular communications in which mobility issues are important. Multiple platform types and cut-off priority for handoffs are considered. Computational issues are discussed and some theoretical performance measures are obtained to demonstrate the method and compare with previous work.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128698563","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}
{"title":"On the relaying capability of the reconfigurable wireless networks","authors":"Z. Haas","doi":"10.1109/VETEC.1997.600510","DOIUrl":"https://doi.org/10.1109/VETEC.1997.600510","url":null,"abstract":"In this paper, we evaluate the performance of an ad-hoc network architecture, investigating the effect of various design and operational parameters on the blocking and dropping probabilities. In particular, we study the improvement in the network coverage due to the multi-hop routing feature. Furthermore, the effect of limiting the path length on the network performance is studied, showing that there is an optimal value for this parameter.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128292705","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}
{"title":"Interference cancellation for improved channel estimation in array processing MLSE receivers","authors":"G. Bottomley, K. Molnar","doi":"10.1109/VETEC.1997.596335","DOIUrl":"https://doi.org/10.1109/VETEC.1997.596335","url":null,"abstract":"Array processing techniques provide significant gains in performance for digital cellular communications systems. While array processing has the potential of mitigating severe co-channel interference, performance is limited by the need to estimate the channel of the desired signal. In this paper, practical approaches for improving channel estimation in the presence of interference are proposed. Simulation of these approaches for the IS-136 TDMA cellular system demonstrate that improved channel estimation can provide gains in C/I as high as 8 dB at 1% BER.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128639964","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}
{"title":"Co-existence DCA: dynamic channel allocations allowing underlaying autonomous microcells","authors":"I. Chih-Lin, M. Haleem","doi":"10.1109/VETEC.1997.605541","DOIUrl":"https://doi.org/10.1109/VETEC.1997.605541","url":null,"abstract":"To facilitate the coexistence of embedded autonomous indoor microcellular environments, a new form of dynamic channel assignment (DCA) algorithms for outdoor macrocellular systems is proposed in this paper. The co-existence of two systems without excessive mutual interference is achieved through a novel mechanism, i.e., intelligent exclusion of predefined subsets of the universal channel set from the dynamic assignment in the outdoor cells. Such channel exclusion results in a guaranteed number of channels available to the autonomous indoor systems anywhere they are; while incurring minimal DCA performance degradation in the macrocells. The resulting DCA algorithms are termed the co-existence DCA (CE-DCA) algorithms. We formulate the problem of CE-DCA in a rigorous manner and discuss the parameters involved in achieving optimum combined capacity of macro and micro cellular systems. Using the local packing dynamic channel assignment (LPDCA) algorithm as the base line DCA in the macrocellular system, we present both statistic and deterministic CE-DCA schemes, and compare their performances under various scenarios.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129258549","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}
{"title":"Performance of multisensor adaptive MLSE in fading channels","authors":"S. Diggavi, A. Paulraj","doi":"10.1109/VETEC.1997.605995","DOIUrl":"https://doi.org/10.1109/VETEC.1997.605995","url":null,"abstract":"We examine the problem of signal detection over time-varying channels using a multisensor adaptive MLSE detection scheme. We develop analytical expressions for the pairwise probability of error for sequence detection in various channel scenarios. Using the pairwise error probability (PEP) expression for perfect channel tracking we show that there is no error flooring. We then derive the PEP when there are channel estimation errors, and through this analysis we examine the error flooring phenomenon. We derive the PEP for colored Gaussian noise channels when we have a mismatched decoder. Using these results we gain some intuition about the role of channel time-variation, channel estimation errors and noise covariance on the performance of multisensor adaptive MLSE. We also propose an adaptive MLSE scheme which could be used in interference limited environments. We present numerical simulation results to demonstrate the performance of these schemes.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"18 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129302073","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}
{"title":"Admission control in frequency hopping GSM systems","authors":"P. Beming, M. Frodigh","doi":"10.1109/VETEC.1997.600538","DOIUrl":"https://doi.org/10.1109/VETEC.1997.600538","url":null,"abstract":"One way to improve the ability to handle offered traffic variations in a cellular system is to use soft capacity, i.e., to have an admission control algorithm that accepts new calls as long as the quality of the already ongoing calls is preserved. The increased flexibility in the use of the radio resources will increase the capacity in the system. In GSM, the operators continuously tighten their cell plans. Suggestions of going to a cluster size of 3 with the help of soft capacity exist. This paper investigates the performance of an admission control algorithm based on the number of active users in each cell. The purpose of the admission control algorithm is to block some calls in order to preserve the quality in the system. By means of simulations it is shown that a traffic load based admission control algorithm works well in a system with cluster size of 3. The results show that the method preserves the quality both when the traffic is uniformly and non-uniformly distributed. The system uses frequency hopping, discontinuous transmission and quality based power control.","PeriodicalId":389634,"journal":{"name":"1997 IEEE 47th Vehicular Technology Conference. Technology in Motion","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114083904","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}