Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726138
Hongzhi Jiao, F. Li
Wireless mesh networks will play an important role in the next-generation wireless communication systems as it can provide wide coverage and scalable broadband Internet access services. However, congestion in such networks may lead to throughput degradation, packet loss and longer transmission delay. Therefore, routing and traffic forwarding schemes which are aware of the congestion status of a wireless network can efficiently improve network performance. In this paper, we propose a new congestion-aware routing scheme which may direct different paths for different services types, according to network congestion status. The goal of this routing scheme is to use traffic load metric for choosing a high throughput path for each mesh client towards the most appropriate Internet gateway so that load balancing is achieved among gateways. Simulations based on ns2 are conducted in order to evaluate the performance of the proposed scheme, considering both UDP and TCP traffic classes. We observe that the proposed scheme outperforms the legacy routing scheme in the simulated scenarios.
{"title":"A service-oriented routing scheme with load balancing in wireless mesh networks","authors":"Hongzhi Jiao, F. Li","doi":"10.1109/ISWCS.2008.4726138","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726138","url":null,"abstract":"Wireless mesh networks will play an important role in the next-generation wireless communication systems as it can provide wide coverage and scalable broadband Internet access services. However, congestion in such networks may lead to throughput degradation, packet loss and longer transmission delay. Therefore, routing and traffic forwarding schemes which are aware of the congestion status of a wireless network can efficiently improve network performance. In this paper, we propose a new congestion-aware routing scheme which may direct different paths for different services types, according to network congestion status. The goal of this routing scheme is to use traffic load metric for choosing a high throughput path for each mesh client towards the most appropriate Internet gateway so that load balancing is achieved among gateways. Simulations based on ns2 are conducted in order to evaluate the performance of the proposed scheme, considering both UDP and TCP traffic classes. We observe that the proposed scheme outperforms the legacy routing scheme in the simulated scenarios.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124445353","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726097
S. Chatzinotas, M. Imran, C. Tzaras
Multiple antennas are known to increase the link throughput by providing a multiplexing gain which scales with the number of antennas. Especially in cellular systems, multiple antennas can be exploited to achieve higher rates without the need for additional base station (BS) sites. In this direction, this paper investigates the multi-antenna capacity scaling in a cellular system which employs multicell processing (hyper-receiver). The model under investigation is a MIMO Gaussian cellular multiple-access channel (GCMAC) over a planar cellular array in the presence of power-law path loss and flat fading. Furthermore, the considered cellular model overcomes the assumption of user collocation utilized by previous models by incorporating uniformly distributed user terminals (UTs). The asymptotic eigenvalue distribution (a.e.d.) of the covariance channel matrix is calculated based on free-probabilistic arguments. In this context, we evaluate the effect of multiple BS/UT antennas on the optimal sum-rate capacity by considering a variable-density cellular system. Finally, the analytical results are interpreted in the context of a typical real-world macrocellular scenario.
{"title":"Uplink capacity of MIMO cellular systems with multicell processing","authors":"S. Chatzinotas, M. Imran, C. Tzaras","doi":"10.1109/ISWCS.2008.4726097","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726097","url":null,"abstract":"Multiple antennas are known to increase the link throughput by providing a multiplexing gain which scales with the number of antennas. Especially in cellular systems, multiple antennas can be exploited to achieve higher rates without the need for additional base station (BS) sites. In this direction, this paper investigates the multi-antenna capacity scaling in a cellular system which employs multicell processing (hyper-receiver). The model under investigation is a MIMO Gaussian cellular multiple-access channel (GCMAC) over a planar cellular array in the presence of power-law path loss and flat fading. Furthermore, the considered cellular model overcomes the assumption of user collocation utilized by previous models by incorporating uniformly distributed user terminals (UTs). The asymptotic eigenvalue distribution (a.e.d.) of the covariance channel matrix is calculated based on free-probabilistic arguments. In this context, we evaluate the effect of multiple BS/UT antennas on the optimal sum-rate capacity by considering a variable-density cellular system. Finally, the analytical results are interpreted in the context of a typical real-world macrocellular scenario.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134287809","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726096
Trong-Anh Huynh, D. Hoang, M. Islam, Jinsang Kim
Breadth-first search sphere decoding (SD) is considered as one of the most promising methods for multiple-input multiple-output (MIMO) detection due to its low computational complexity, capability of providing fixed throughput and pipelining features. However, the performance of the conventional breadth-first search SD is significantly degraded if the number of candidate symbols kept at each level of the tree search is not sufficiently large. To solve this problem, we present a novel two-level-search sphere decoding algorithm for MIMO systems. In our proposed algorithm, symbol detection is concurrently performed on two levels of the tree search, and the search space is extended to find good candidate symbols. The use of simultaneous two-level search is to greatly reduce the possibility of discarding good candidates at early stages. Compared to the traditional breadth-first search SD algorithm, our approach provides a performance gain of about 2.5 dB at a bit-error-rate (BER) of 10-4. Our work also exhibits a low computational complexity in term of the number of multiplications. Furthermore, we also discuss some VLSI implementation aspects of the proposed algorithm for practical applications.
{"title":"Two-level-search sphere decoding algorithm for MIMO detection","authors":"Trong-Anh Huynh, D. Hoang, M. Islam, Jinsang Kim","doi":"10.1109/ISWCS.2008.4726096","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726096","url":null,"abstract":"Breadth-first search sphere decoding (SD) is considered as one of the most promising methods for multiple-input multiple-output (MIMO) detection due to its low computational complexity, capability of providing fixed throughput and pipelining features. However, the performance of the conventional breadth-first search SD is significantly degraded if the number of candidate symbols kept at each level of the tree search is not sufficiently large. To solve this problem, we present a novel two-level-search sphere decoding algorithm for MIMO systems. In our proposed algorithm, symbol detection is concurrently performed on two levels of the tree search, and the search space is extended to find good candidate symbols. The use of simultaneous two-level search is to greatly reduce the possibility of discarding good candidates at early stages. Compared to the traditional breadth-first search SD algorithm, our approach provides a performance gain of about 2.5 dB at a bit-error-rate (BER) of 10-4. Our work also exhibits a low computational complexity in term of the number of multiplications. Furthermore, we also discuss some VLSI implementation aspects of the proposed algorithm for practical applications.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134313445","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726028
C. Oberli, D. Landau
Passenger counting is an important task for intelligent public transportation system¿s planning and operation. However, traditional counting systems can¿t identify individual passengers. The access to this additional capacity would allow collecting historical statistics on each passenger¿s transportation needs, hence enabling a substantially enhanced optimization in these systems. With this purpose, this work proposes a passenger counting and identification method through radio frequency identification technologies (RFID). Forty individuals are involved in measurements carrying EPC Gen2 tags in their backpacks, wallets, pocket and hand, passing through a portal with a similar size as a bus door. Conditions of one and two rows of persons walking through the portal are evaluated. This portal is equipped with 4 reading antennas. Cards that have a single EPC Gen2 tag and cards with both a Mifare and a UHF EPC Gen2 tag are used. Card reading statistics for all the combinations of 1, 2, 3 and 4 antennas are presented in this paper. The passenger detection percentage at the portal with two properly located antennas has an average of 82% for dual-band cards and 91% for single-band cards. When four antennas are used, there is an additional increase of 2% in the detection percentage for both types of cards.
{"title":"Performance evaluation of UHF RFID technologies for real-time passenger tracking in intelligent public transportation systems","authors":"C. Oberli, D. Landau","doi":"10.1109/ISWCS.2008.4726028","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726028","url":null,"abstract":"Passenger counting is an important task for intelligent public transportation system¿s planning and operation. However, traditional counting systems can¿t identify individual passengers. The access to this additional capacity would allow collecting historical statistics on each passenger¿s transportation needs, hence enabling a substantially enhanced optimization in these systems. With this purpose, this work proposes a passenger counting and identification method through radio frequency identification technologies (RFID). Forty individuals are involved in measurements carrying EPC Gen2 tags in their backpacks, wallets, pocket and hand, passing through a portal with a similar size as a bus door. Conditions of one and two rows of persons walking through the portal are evaluated. This portal is equipped with 4 reading antennas. Cards that have a single EPC Gen2 tag and cards with both a Mifare and a UHF EPC Gen2 tag are used. Card reading statistics for all the combinations of 1, 2, 3 and 4 antennas are presented in this paper. The passenger detection percentage at the portal with two properly located antennas has an average of 82% for dual-band cards and 91% for single-band cards. When four antennas are used, there is an additional increase of 2% in the detection percentage for both types of cards.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133680254","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726079
Luc Gadbois, P. Koutsakis
We have recently introduced in the literature a new access control protocol for next generation wireless cellular networks, which showed superior performance in comparison to other (TDMA and WCDMA-based) protocols when integrating various types of multimedia traffic. In this Extended Abstract, we show that the use of stack protocols to resolve contention among contending multimedia terminals is not the only satisfactory solution. Although stack protocols have been shown in the literature to be operationally simple and stable, the use of efficient backlog estimation can help the system achieve near-optimal throughput with slotted Aloha-based contention, while integrating streams from latest technology video encoders with other types of packet traffic over noisy wireless cellular networks.
{"title":"Using efficient backlog estimation to achieve near-optimal throughput for integrated multimedia wireless cellular access","authors":"Luc Gadbois, P. Koutsakis","doi":"10.1109/ISWCS.2008.4726079","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726079","url":null,"abstract":"We have recently introduced in the literature a new access control protocol for next generation wireless cellular networks, which showed superior performance in comparison to other (TDMA and WCDMA-based) protocols when integrating various types of multimedia traffic. In this Extended Abstract, we show that the use of stack protocols to resolve contention among contending multimedia terminals is not the only satisfactory solution. Although stack protocols have been shown in the literature to be operationally simple and stable, the use of efficient backlog estimation can help the system achieve near-optimal throughput with slotted Aloha-based contention, while integrating streams from latest technology video encoders with other types of packet traffic over noisy wireless cellular networks.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133972787","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726103
Wei Chen, Qinye Yin, Aigang Feng
In smart antenna downlink systems, the beamforming is severely affected by antenna gain and phase mismatch as well as mutual coupling effects. We propose an eigen-structure based approach to estimate the gain and phase of each antenna sensor and mutual coupling coefficients between antenna sensors. By preprocessing the transmission signal in base station with the estimated parameters, the gain and phase mismatch and mutual coupling effects are compensated. Simulation results with data collected from a smart antenna test bed show that the estimation error is less than 5% and correct beam pattern is obtained.
{"title":"Array calibration for compensating gain/phase mismatch and mutual coupling effects in Smart Antenna Systems","authors":"Wei Chen, Qinye Yin, Aigang Feng","doi":"10.1109/ISWCS.2008.4726103","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726103","url":null,"abstract":"In smart antenna downlink systems, the beamforming is severely affected by antenna gain and phase mismatch as well as mutual coupling effects. We propose an eigen-structure based approach to estimate the gain and phase of each antenna sensor and mutual coupling coefficients between antenna sensors. By preprocessing the transmission signal in base station with the estimated parameters, the gain and phase mismatch and mutual coupling effects are compensated. Simulation results with data collected from a smart antenna test bed show that the estimation error is less than 5% and correct beam pattern is obtained.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122101513","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726140
H. Hernández, C. Blum
In wireless ad-hoc networks, where nodes are often equipped with batteries, energy is a scarce resource. Therefore, power consumption of network operations is critical and subject to optimization. One of the fundamental problems in ad-hoc networks is multicasting. In this work we consider the so-called minimum energy multicast (MEM) problem, which can be stated as a combinatorial optimization problem. We develop an ant colony optimization metaheuristic for networks with omni-directional and directional antennas. The results show that our algorithm consistently outperforms existing techniques.
{"title":"Energy-efficient multicasting in wireless ad-hoc networks: An ant colony optimization approach","authors":"H. Hernández, C. Blum","doi":"10.1109/ISWCS.2008.4726140","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726140","url":null,"abstract":"In wireless ad-hoc networks, where nodes are often equipped with batteries, energy is a scarce resource. Therefore, power consumption of network operations is critical and subject to optimization. One of the fundamental problems in ad-hoc networks is multicasting. In this work we consider the so-called minimum energy multicast (MEM) problem, which can be stated as a combinatorial optimization problem. We develop an ant colony optimization metaheuristic for networks with omni-directional and directional antennas. The results show that our algorithm consistently outperforms existing techniques.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123907177","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726116
Y. Kishino, Yasushi Sakurai, Koji Kamei, Y. Yanagisawa, T. Maekawa, T. Okadome
The method proposed here gathers data in high- density wireless sensor networks in real-time. It determines network topology by hierarchical clustering to avoid radio collision, which enables us to gather data with minimum data latency from numerous high-density sensor nodes. The analysis of our proposed tree-based data gathering protocol and real experiments using 39 real sensor nodes show that the proposed data gathering method can reduce data latency by hierarchical clustering.
{"title":"Data gathering in high-density wireless sensor networks using hierarchical clustering","authors":"Y. Kishino, Yasushi Sakurai, Koji Kamei, Y. Yanagisawa, T. Maekawa, T. Okadome","doi":"10.1109/ISWCS.2008.4726116","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726116","url":null,"abstract":"The method proposed here gathers data in high- density wireless sensor networks in real-time. It determines network topology by hierarchical clustering to avoid radio collision, which enables us to gather data with minimum data latency from numerous high-density sensor nodes. The analysis of our proposed tree-based data gathering protocol and real experiments using 39 real sensor nodes show that the proposed data gathering method can reduce data latency by hierarchical clustering.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125324559","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726059
Myunghwan Seo, Yonggyu Kim, Joongsoo Ma
Multi-channel MAC protocols are proposed to increase the capacity of wireless network. However, dynamic channel selection mechanism based on channel usage information from one-hop neighbor nodes causes multi-channel hidden node problems in a multi-channel multi-hop wireless network. In this paper, we propose a new approach of channel selection. Nodes snoop data channels during idle times and then select an idle data channel within the carrier sensing range by using both the snooping results and the channel usage information. Our simulation results verify that the proposed channel selection approach can effectively avoid the multi-channel hidden node problem and improve the networkwide performance.
{"title":"A multi-channel MAC protocol with snooping for multi-hop wireless nmetworks","authors":"Myunghwan Seo, Yonggyu Kim, Joongsoo Ma","doi":"10.1109/ISWCS.2008.4726059","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726059","url":null,"abstract":"Multi-channel MAC protocols are proposed to increase the capacity of wireless network. However, dynamic channel selection mechanism based on channel usage information from one-hop neighbor nodes causes multi-channel hidden node problems in a multi-channel multi-hop wireless network. In this paper, we propose a new approach of channel selection. Nodes snoop data channels during idle times and then select an idle data channel within the carrier sensing range by using both the snooping results and the channel usage information. Our simulation results verify that the proposed channel selection approach can effectively avoid the multi-channel hidden node problem and improve the networkwide performance.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129396766","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 : 2008-12-30DOI: 10.1109/ISWCS.2008.4726057
J. Penttinen
The typical radiating power levels of the DVB-H sites are normally between the values used in mobile and television broadcast networks. It is thus important to take into account accordingly the EMC (Electro Magnetic Compatibility) as well as the human exposure limits in the DVB-H transmission facilities. This paper presents a practical method for estimating the safety limits of human exposure and EMC in different DVB-H installation environments. Furthermore, case studies are presented for the most typical environments.
{"title":"DVB-H radiation aspects","authors":"J. Penttinen","doi":"10.1109/ISWCS.2008.4726057","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726057","url":null,"abstract":"The typical radiating power levels of the DVB-H sites are normally between the values used in mobile and television broadcast networks. It is thus important to take into account accordingly the EMC (Electro Magnetic Compatibility) as well as the human exposure limits in the DVB-H transmission facilities. This paper presents a practical method for estimating the safety limits of human exposure and EMC in different DVB-H installation environments. Furthermore, case studies are presented for the most typical environments.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130935118","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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