Pub Date : 2007-12-04DOI: 10.1109/ISWCS.2007.4392300
A. Knopp, C. Hofmann, R. Schwarz, M. Chouayakh, B. Lankl
A novel strategy of precalculating potential MIMO spectral efficiencies of correlated channels based on single, measured or appropriately modeled SISO impulse responses is presented. Additionally, the model is capable of comprising the physical nature of the channel in form of its frequency response. The method is applied to indoor MIMO channels where the correlation is introduced by a strong Line-Of-Sight signal component as well as low mobility. It is verified by simulation as well as based on results from measurements which were derived using a fast MIMO radio channel sounder. A spherical wave model is applied and the distributions of angle of arrival and angle of departure turn out to be important modeling parameters. Consequentially, earlier results on the impact of the antenna arrangement on the MIMO spectral efficiency are supported for the observed, short-range channels. The presented strategy is especially viable to utilize and extend available data records from SISO measurement campaigns to the MIMO case, where the focus lies on the prediction of spatial MIMO spectral efficiencies.
{"title":"Spatial Capacity Estimation for Correlated MIMO Channels Based on Measured SISO Data Records","authors":"A. Knopp, C. Hofmann, R. Schwarz, M. Chouayakh, B. Lankl","doi":"10.1109/ISWCS.2007.4392300","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392300","url":null,"abstract":"A novel strategy of precalculating potential MIMO spectral efficiencies of correlated channels based on single, measured or appropriately modeled SISO impulse responses is presented. Additionally, the model is capable of comprising the physical nature of the channel in form of its frequency response. The method is applied to indoor MIMO channels where the correlation is introduced by a strong Line-Of-Sight signal component as well as low mobility. It is verified by simulation as well as based on results from measurements which were derived using a fast MIMO radio channel sounder. A spherical wave model is applied and the distributions of angle of arrival and angle of departure turn out to be important modeling parameters. Consequentially, earlier results on the impact of the antenna arrangement on the MIMO spectral efficiency are supported for the observed, short-range channels. The presented strategy is especially viable to utilize and extend available data records from SISO measurement campaigns to the MIMO case, where the focus lies on the prediction of spatial MIMO spectral efficiencies.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"168 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115485326","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392448
Dimitris V. Vlachos, Stamatis N. Sivitos, M. Hadjinicolaou
In this paper a novel joint blind channel estimation and carrier offset method for code division multiple access (CDMA) is proposed. The new method combines singular value decomposition (SVD) analysis with carrier-offset parameter, which was not taken into account previously in the matrix power method. The simulation results obtained from the proposed scheme show that a better performance is achieved compared with other schemes in the literature. Also, the computational cost is much lower compared with other schemes because the mathematical model is independent of the need of knowledge of the noise subspace.
{"title":"Novel Joint Blind Channel and Carrier Offset Estimation Method for CDMA Systems","authors":"Dimitris V. Vlachos, Stamatis N. Sivitos, M. Hadjinicolaou","doi":"10.1109/ISWCS.2007.4392448","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392448","url":null,"abstract":"In this paper a novel joint blind channel estimation and carrier offset method for code division multiple access (CDMA) is proposed. The new method combines singular value decomposition (SVD) analysis with carrier-offset parameter, which was not taken into account previously in the matrix power method. The simulation results obtained from the proposed scheme show that a better performance is achieved compared with other schemes in the literature. Also, the computational cost is much lower compared with other schemes because the mathematical model is independent of the need of knowledge of the noise subspace.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"190 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124923040","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392297
G. Venkataraman, S. Emmanuel, S. Thambipillai
Wireless sensor networks (WSN) are inherently fault- prone due to the shared wireless communication medium and harsh environments in which they are deployed. Energy is one of the most constraining factors and node failures due to crash and energy exhaustion are commonplace. In order to avoid degradation of service due to faults, it is necessary for the WSN to be able to detect faults early and initiate recovery actions. In this paper we propose a localized cluster based method for fault detection and network connectivity recovery which is energy efficient and responsive. Extensive simulations show that our proposed algorithm with cluster size 20 enables the network to recover from faults in one fourth of the time consumed by fault tolerant clustering method (Gupta algorithm). Our proposed method is also shown to consume less energy than crash faults identification method. The proposed algorithm lends well to the continuous operation and maintenance of robust sensor networks.
{"title":"A Cluster-Based Approach to Fault Detection and Recovery in Wireless Sensor Networks","authors":"G. Venkataraman, S. Emmanuel, S. Thambipillai","doi":"10.1109/ISWCS.2007.4392297","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392297","url":null,"abstract":"Wireless sensor networks (WSN) are inherently fault- prone due to the shared wireless communication medium and harsh environments in which they are deployed. Energy is one of the most constraining factors and node failures due to crash and energy exhaustion are commonplace. In order to avoid degradation of service due to faults, it is necessary for the WSN to be able to detect faults early and initiate recovery actions. In this paper we propose a localized cluster based method for fault detection and network connectivity recovery which is energy efficient and responsive. Extensive simulations show that our proposed algorithm with cluster size 20 enables the network to recover from faults in one fourth of the time consumed by fault tolerant clustering method (Gupta algorithm). Our proposed method is also shown to consume less energy than crash faults identification method. The proposed algorithm lends well to the continuous operation and maintenance of robust sensor networks.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129641944","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392421
J. Rodas, T. Fernández, D. Iglesia, C. Escudero
In this paper we introduce a Bluetooth system which achieves an important improvement in the RSSI stability thanks to the use of multiple antennas. The main advantage of our system is that it reduces the effects produced by fading in the received signal power, that is obtained by the RSSI (received signal strength indicator). In most positioning systems the RSSI stability is very important, because it is the main reference for obtaining the desired positions. Using spatial diversity our system tries to stabilize this RSSI measurement. We present a study of this important improvement in which we compare different combination/selection techniques which use the RSSIs obtained from the received signals. We have carried out an empirical evaluation of this multiple antenna Bluetooth system, and we have verified how these spatial diversity techniques reduce the mean square error of the measured RSSI with respect to a theoretical propagation model.
{"title":"Multiple Antennas Bluetooth System for RSSI Stabilization","authors":"J. Rodas, T. Fernández, D. Iglesia, C. Escudero","doi":"10.1109/ISWCS.2007.4392421","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392421","url":null,"abstract":"In this paper we introduce a Bluetooth system which achieves an important improvement in the RSSI stability thanks to the use of multiple antennas. The main advantage of our system is that it reduces the effects produced by fading in the received signal power, that is obtained by the RSSI (received signal strength indicator). In most positioning systems the RSSI stability is very important, because it is the main reference for obtaining the desired positions. Using spatial diversity our system tries to stabilize this RSSI measurement. We present a study of this important improvement in which we compare different combination/selection techniques which use the RSSIs obtained from the received signals. We have carried out an empirical evaluation of this multiple antenna Bluetooth system, and we have verified how these spatial diversity techniques reduce the mean square error of the measured RSSI with respect to a theoretical propagation model.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129904961","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392292
C. Nelson, L. Fagoonee
Partial Unit Memory (PUM) codes are a class of low complexity, non-binary convolutional codes and have been shown recently to outperform equivalent convolutional codes. We present the Extrinsic Information Transfer (EXIT) charts of parallel concatenated PUM codes and PUM Woven Turbo Codes and analyse them to assess their performance compared with well-known turbo codes used by the third generation mobile UMTS standard. The EXIT chart analysis is supported by Bit Error Rate (BER) plots. We show that the concatenated PUM codes outperform the well-known turbo codes in the error floor region, with comparable performance in the waterfall region.
{"title":"EXIT Charts for PUM Woven Turbo Codes","authors":"C. Nelson, L. Fagoonee","doi":"10.1109/ISWCS.2007.4392292","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392292","url":null,"abstract":"Partial Unit Memory (PUM) codes are a class of low complexity, non-binary convolutional codes and have been shown recently to outperform equivalent convolutional codes. We present the Extrinsic Information Transfer (EXIT) charts of parallel concatenated PUM codes and PUM Woven Turbo Codes and analyse them to assess their performance compared with well-known turbo codes used by the third generation mobile UMTS standard. The EXIT chart analysis is supported by Bit Error Rate (BER) plots. We show that the concatenated PUM codes outperform the well-known turbo codes in the error floor region, with comparable performance in the waterfall region.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126198785","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392378
Dagang Li, J. Theunis, K. Sleurs, J. Potemans, E. V. Van Lil, A. R. Van de Capelle
The random early detection (RED) is a widely used active queue management (AQM) algorithm for congestion avoidance. It monitors the average queue length to detect incipient congestion and notifies the connections of congestion to adjust their sending rate. During a handover, all the active connections of the mobile node will be diverted to the new network and increase the total traffic there immediately. Because RED uses an exponential weighted moving average (EWMA) to calculate the queue length, it will be too slow to track this rapid change and fail to react correctly. In this paper we propose a dual RED algorithm to accommodate the coming handed-over connections quickly while keeping the link utilization high. The improvement is verified with simulations.
{"title":"Improving RED Performance during Handovers in Wireless IP Networks","authors":"Dagang Li, J. Theunis, K. Sleurs, J. Potemans, E. V. Van Lil, A. R. Van de Capelle","doi":"10.1109/ISWCS.2007.4392378","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392378","url":null,"abstract":"The random early detection (RED) is a widely used active queue management (AQM) algorithm for congestion avoidance. It monitors the average queue length to detect incipient congestion and notifies the connections of congestion to adjust their sending rate. During a handover, all the active connections of the mobile node will be diverted to the new network and increase the total traffic there immediately. Because RED uses an exponential weighted moving average (EWMA) to calculate the queue length, it will be too slow to track this rapid change and fail to react correctly. In this paper we propose a dual RED algorithm to accommodate the coming handed-over connections quickly while keeping the link utilization high. The improvement is verified with simulations.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131486357","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392302
B. EduardoZacarías, S. Werner, R. Wichman
This work presents a transmission strategy for closed-loop MIMO systems, where compact feedback messages meant for transmit weight adaptation are also used to convey basic link adaptation requests that can improve the link reliability or the data throughput without additional feedback overhead. The proposed link adaptation varies the number of orthogonal transmit beams and the symbol modulation employed on each beam. The simulation study focuses in a system with four transmit and two receive antennas, with constant data rate and two different underlying beamforming schemes: a recently proposed Jacobi beamformer, and a Grassmanian codebook approach. It is shown that both schemes can obtain an improvement of around 1 dB in bit error probability (BEP) performance, in slowly fading and spatially uncorrelated channels, compared to the case where both beams are used all the time. The application of the proposed technique to other precoding algorithms is briefly discussed.
{"title":"Link adaptation with distributed Jacobi eigenbeamforming for MIMO systems","authors":"B. EduardoZacarías, S. Werner, R. Wichman","doi":"10.1109/ISWCS.2007.4392302","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392302","url":null,"abstract":"This work presents a transmission strategy for closed-loop MIMO systems, where compact feedback messages meant for transmit weight adaptation are also used to convey basic link adaptation requests that can improve the link reliability or the data throughput without additional feedback overhead. The proposed link adaptation varies the number of orthogonal transmit beams and the symbol modulation employed on each beam. The simulation study focuses in a system with four transmit and two receive antennas, with constant data rate and two different underlying beamforming schemes: a recently proposed Jacobi beamformer, and a Grassmanian codebook approach. It is shown that both schemes can obtain an improvement of around 1 dB in bit error probability (BEP) performance, in slowly fading and spatially uncorrelated channels, compared to the case where both beams are used all the time. The application of the proposed technique to other precoding algorithms is briefly discussed.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134367493","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392355
B. Zhen, Huan-Bang Li, R. Kohno
IEEE 802.15 working group established a new study group, body area network (SG-BAN), to develop short range wireless communication technology in and around human body recently. Wearable healthcare is an important category of potential applications of BAN. This paper introduces the IEEE SG-BAN and investigates the performance of 802.15.4b and 802.15.4a for wearable healthcare applications in the heterogeneous networks environment. The object is better understanding of healthcare requirement of BAN and how and where BAN works to be started. In addition to the scalability issue, we found asymmetric clear channel assessment (CCA) abilities among different types of wireless technology. The asymmetric CCA has significant impact on system performance.
{"title":"IEEE Body Area Networks for Medical Applications","authors":"B. Zhen, Huan-Bang Li, R. Kohno","doi":"10.1109/ISWCS.2007.4392355","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392355","url":null,"abstract":"IEEE 802.15 working group established a new study group, body area network (SG-BAN), to develop short range wireless communication technology in and around human body recently. Wearable healthcare is an important category of potential applications of BAN. This paper introduces the IEEE SG-BAN and investigates the performance of 802.15.4b and 802.15.4a for wearable healthcare applications in the heterogeneous networks environment. The object is better understanding of healthcare requirement of BAN and how and where BAN works to be started. In addition to the scalability issue, we found asymmetric clear channel assessment (CCA) abilities among different types of wireless technology. The asymmetric CCA has significant impact on system performance.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132680971","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392323
Baris Özgül, M. Koca, H. Deliç, Gordon L. Stüber
In this paper, a channel precoding technique is proposed for M-ary continuous phase modulation (CPM) for multipath downlink channels. The proposed pre-equalizer depends on the approximation of CPM signals by complex exponential functions and applies modulo-arithmetic operations to ensure stability, as in Tomlinson-Harashima precoding. Then spectrally efficient precoded signals are obtained with small envelope variations by employing a transmit selection diversity technique. By transferring the equalization functions to the base station, complexity in the mobile terminals is reduced significantly. The simulation results depict the power spectral density of the transmitted signals and the bit-error rate performance.
{"title":"Pre-Equalization of Continuous Phase Modulation for Multipath Fading Channels","authors":"Baris Özgül, M. Koca, H. Deliç, Gordon L. Stüber","doi":"10.1109/ISWCS.2007.4392323","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392323","url":null,"abstract":"In this paper, a channel precoding technique is proposed for M-ary continuous phase modulation (CPM) for multipath downlink channels. The proposed pre-equalizer depends on the approximation of CPM signals by complex exponential functions and applies modulo-arithmetic operations to ensure stability, as in Tomlinson-Harashima precoding. Then spectrally efficient precoded signals are obtained with small envelope variations by employing a transmit selection diversity technique. By transferring the equalization functions to the base station, complexity in the mobile terminals is reduced significantly. The simulation results depict the power spectral density of the transmitted signals and the bit-error rate performance.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131808639","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 : 2007-12-04DOI: 10.1109/ISWCS.2007.4392374
H. Khuong, T. Le-Ngoc
We propose a coded cooperation scheme based on turbo encoding/decoding, in which only newly generated parity bits of the partner are sent if the user successfully decodes its partner's information in order to improve bandwidth efficiency. The proposed encoding structure introduces correlation between users' data over multiple frames, which offers effectively longer codes and facilitates high-performance iterative multi-user decoding at the destination. Additionally, the iterative decoding over multiple frames can provide time diversity besides spatial diversity inherent in user-cooperation even for flat block fading channels. Simulation results show that the proposed scheme significantly outperforms direct transmission for the same transmit power and bandwidth efficiency.
{"title":"A Bandwidth-efficient Coded User-Cooperation Scheme for Flat Block Fading Channels","authors":"H. Khuong, T. Le-Ngoc","doi":"10.1109/ISWCS.2007.4392374","DOIUrl":"https://doi.org/10.1109/ISWCS.2007.4392374","url":null,"abstract":"We propose a coded cooperation scheme based on turbo encoding/decoding, in which only newly generated parity bits of the partner are sent if the user successfully decodes its partner's information in order to improve bandwidth efficiency. The proposed encoding structure introduces correlation between users' data over multiple frames, which offers effectively longer codes and facilitates high-performance iterative multi-user decoding at the destination. Additionally, the iterative decoding over multiple frames can provide time diversity besides spatial diversity inherent in user-cooperation even for flat block fading channels. Simulation results show that the proposed scheme significantly outperforms direct transmission for the same transmit power and bandwidth efficiency.","PeriodicalId":261480,"journal":{"name":"2007 4th International Symposium on Wireless Communication Systems","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133427377","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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