Pub Date : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700084
Y. Tang, M. Brandt-Pearce, S. Wilson
Parallel channel models are common in wireless communication systems. In this paper, we propose an algorithm to maximize the throughput of two independent parallel channels over allowed encoder rate and modem rate constraints by adapting system parameters according to known channel state information. Theoretical results are presented and applied to a hybrid free space optical (FSO)/radio frequency (RF) communication system.
{"title":"Link adaptation for parallel channels with encoder rate and modem symbol rate constraints","authors":"Y. Tang, M. Brandt-Pearce, S. Wilson","doi":"10.1109/GLOCOMW.2010.5700084","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700084","url":null,"abstract":"Parallel channel models are common in wireless communication systems. In this paper, we propose an algorithm to maximize the throughput of two independent parallel channels over allowed encoder rate and modem rate constraints by adapting system parameters according to known channel state information. Theoretical results are presented and applied to a hybrid free space optical (FSO)/radio frequency (RF) communication system.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114607228","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700151
Hui Zhou, K. Anwar, T. Matsumoto
This paper proposes a novel Single Carrier Frequency Division Multiple Access (SC-FDMA) System without Cyclic Prefix based on the Chained Turbo Equalization (CHATUE) algorithm, which connects turbo equalizers neighboring in time to eliminate the Inter-Block Interference (IBI). Results of Extrinsic Information Transfer (EXIT) chart demonstrate that the performance can be improved by performing iterations between neighboring blocks. In addition, this paper also proposes a complexity reduction technique. The numerical results verify the performance improvement and superiority of the proposed technique over the conventional SC-FDMA transmission, without requiring high computational complexity.
本文提出了一种基于链式Turbo均衡(CHATUE)算法的无循环前缀单载波频分多址(SC-FDMA)系统，该系统及时连接相邻的Turbo均衡器以消除块间干扰(IBI)。外部信息传递(Extrinsic Information Transfer, EXIT)图的结果表明，在相邻块之间进行迭代可以提高性能。此外，本文还提出了一种降低复杂性的技术。数值结果验证了该技术相对于传统SC-FDMA传输的性能改进和优越性，且不需要很高的计算复杂度。
{"title":"Chained Turbo Equalization for SC-FDMA Systems without Cyclic Prefix","authors":"Hui Zhou, K. Anwar, T. Matsumoto","doi":"10.1109/GLOCOMW.2010.5700151","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700151","url":null,"abstract":"This paper proposes a novel Single Carrier Frequency Division Multiple Access (SC-FDMA) System without Cyclic Prefix based on the Chained Turbo Equalization (CHATUE) algorithm, which connects turbo equalizers neighboring in time to eliminate the Inter-Block Interference (IBI). Results of Extrinsic Information Transfer (EXIT) chart demonstrate that the performance can be improved by performing iterations between neighboring blocks. In addition, this paper also proposes a complexity reduction technique. The numerical results verify the performance improvement and superiority of the proposed technique over the conventional SC-FDMA transmission, without requiring high computational complexity.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116669752","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700201
Fuyu Liu, G. Hamza-Lup, K. Hua
Most existing cloaking techniques are based on a three-tier architecture: mobile users, a trusted anonymizer server, and service providers. In this paper, we propose a new three-tier architecture, where the trusted anonymizer server also serves as a broadcast server. The trusted anonymizer server takes a proactive approach. It first groups mobile users into clusters. Then for each cluster, it fetches the most popular query results from service providers. The query results are then broadcast through an air channel to reach all mobile users. As a result, to get a query answered, a mobile user can first tune into the air channel to determine if the query result is available. If not, the mobile user just sends a traditional location-based query to the trusted anonymizer server. Other than the novel new three-tier architecture, we also propose two cell-based clustering algorithms, and a broadcast index to facilitate the download of query results. The proposed techniques are compared using simulation against the improved Interval Cloak technique under the traditional three-tier architecture. The extensive results show that our system is better in reducing communication cost and protecting user privacy.
{"title":"Using broadcast to protect user privacy in location-based applications","authors":"Fuyu Liu, G. Hamza-Lup, K. Hua","doi":"10.1109/GLOCOMW.2010.5700201","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700201","url":null,"abstract":"Most existing cloaking techniques are based on a three-tier architecture: mobile users, a trusted anonymizer server, and service providers. In this paper, we propose a new three-tier architecture, where the trusted anonymizer server also serves as a broadcast server. The trusted anonymizer server takes a proactive approach. It first groups mobile users into clusters. Then for each cluster, it fetches the most popular query results from service providers. The query results are then broadcast through an air channel to reach all mobile users. As a result, to get a query answered, a mobile user can first tune into the air channel to determine if the query result is available. If not, the mobile user just sends a traditional location-based query to the trusted anonymizer server. Other than the novel new three-tier architecture, we also propose two cell-based clustering algorithms, and a broadcast index to facilitate the download of query results. The proposed techniques are compared using simulation against the improved Interval Cloak technique under the traditional three-tier architecture. The extensive results show that our system is better in reducing communication cost and protecting user privacy.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116265849","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700103
Bayrem Triki, S. Rekhis, N. Boudriga
This paper proposes a system for digital investigation in Vehicular Adhoc Networks (VANets). A set of communicating and cooperating components, entitled observers, which are in charge of evidence collection, are integrated into the On-board and Road-Side units of the VANet. The analysis of evidences is performed at the Road-Side level, to identify occurred attacks and determine the identities and location of nodes responsible of the attack. In this proposal, Radio Frequency Identification (RFID) technology is used to support storage and delivery of evidences. The latter provides immediate access to evidences, and facilities the integration of the investigation-based components to vehicles. A case study, dealing with the investigation of a download to fail attack on a firmware update over the air, is also presented.
{"title":"An RFID based system for digital investigation in Vehicular Adhoc Networks","authors":"Bayrem Triki, S. Rekhis, N. Boudriga","doi":"10.1109/GLOCOMW.2010.5700103","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700103","url":null,"abstract":"This paper proposes a system for digital investigation in Vehicular Adhoc Networks (VANets). A set of communicating and cooperating components, entitled observers, which are in charge of evidence collection, are integrated into the On-board and Road-Side units of the VANet. The analysis of evidences is performed at the Road-Side level, to identify occurred attacks and determine the identities and location of nodes responsible of the attack. In this proposal, Radio Frequency Identification (RFID) technology is used to support storage and delivery of evidences. The latter provides immediate access to evidences, and facilities the integration of the investigation-based components to vehicles. A case study, dealing with the investigation of a download to fail attack on a firmware update over the air, is also presented.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"192 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123329450","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700292
Efstratios G. Dimopoulos, P. A. Frangoudis, George C. Polyzos
With the low installation and maintenance cost of IEEE 802.11-based equipment, dense Wi-Fi deployments are a reality, especially in today's urban areas. This vast number of WLANs can be exploited to achieve low-cost ubiquitous wireless Internet access, which is also demostrated by the emergence of community-based wireless access schemes. In our prior work we have developed a reciprocity-based peer-to-peer architecture for Wi-Fi sharing, where peers provide free Wi-Fi access to others in order to enjoy the same benefit when they are away from their own Wi-Fi network. Our system tries to match peer consumption with contribution and we have shown it to work well for city-scale Wi-Fi sharing communities. However, when attempting to roam outside the city boundaries, the statistics are such that there is typically a lack of consumption-contribution information between consuming and providing members, which hinders the system's scalability. In this work, we extend our architecture with global-scale roaming capabilities by relaxing the requirement for full decentralization. In particular, we exploit special trusted super-peers which act as representatives of different Wi-Fi sharing communities (e.g., communities of different geographical regions) and which mediate transactions when there is insufficient information about peer contribution history. Extensive simulations show that this super-peer-assisted approach can significantly enhance the system's performance in terms of roaming coverage.
{"title":"Exploiting super peers for large-scale peer-to-peer Wi-Fi roaming","authors":"Efstratios G. Dimopoulos, P. A. Frangoudis, George C. Polyzos","doi":"10.1109/GLOCOMW.2010.5700292","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700292","url":null,"abstract":"With the low installation and maintenance cost of IEEE 802.11-based equipment, dense Wi-Fi deployments are a reality, especially in today's urban areas. This vast number of WLANs can be exploited to achieve low-cost ubiquitous wireless Internet access, which is also demostrated by the emergence of community-based wireless access schemes. In our prior work we have developed a reciprocity-based peer-to-peer architecture for Wi-Fi sharing, where peers provide free Wi-Fi access to others in order to enjoy the same benefit when they are away from their own Wi-Fi network. Our system tries to match peer consumption with contribution and we have shown it to work well for city-scale Wi-Fi sharing communities. However, when attempting to roam outside the city boundaries, the statistics are such that there is typically a lack of consumption-contribution information between consuming and providing members, which hinders the system's scalability. In this work, we extend our architecture with global-scale roaming capabilities by relaxing the requirement for full decentralization. In particular, we exploit special trusted super-peers which act as representatives of different Wi-Fi sharing communities (e.g., communities of different geographical regions) and which mediate transactions when there is insufficient information about peer contribution history. Extensive simulations show that this super-peer-assisted approach can significantly enhance the system's performance in terms of roaming coverage.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124957068","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700366
Bruno Vidalenc, L. Ciavaglia
Carrier networks need to provide their customers with high availability of communication services. Unfortunately, failures are managed by recovery mechanisms getting involved only after the failure occurrence to limit the impact on traffic flows. However, there are often forewarning signs that a network device will stop working properly. We propose to take into account this risk exposure in order to improve the performance of the existing restoration mechanisms, in particular for IP networks. Based on an embedded and real-time risk-level assessment, we can perform a proactive fault-management and isolate the failing routers out of the routed topology, and thus totally avoid service unavailability. Our novel approach enables routers to preventively steer traffic away from risky paths by temporally tuning OSPF link cost.
{"title":"Proactive fault management based on risk-augmented routing","authors":"Bruno Vidalenc, L. Ciavaglia","doi":"10.1109/GLOCOMW.2010.5700366","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700366","url":null,"abstract":"Carrier networks need to provide their customers with high availability of communication services. Unfortunately, failures are managed by recovery mechanisms getting involved only after the failure occurrence to limit the impact on traffic flows. However, there are often forewarning signs that a network device will stop working properly. We propose to take into account this risk exposure in order to improve the performance of the existing restoration mechanisms, in particular for IP networks. Based on an embedded and real-time risk-level assessment, we can perform a proactive fault-management and isolate the failing routers out of the routed topology, and thus totally avoid service unavailability. Our novel approach enables routers to preventively steer traffic away from risky paths by temporally tuning OSPF link cost.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121598436","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700191
Neil Cowzer, P. Nixon
Publish-subscribe systems are well suited loosely decoupled nature of the web, resulting in the messaging paradigm gaining widespread adoption and being the subject of much research. Such research has focused primarily on architectures and filtering algorithms with little evidence of performance analysis or characterization of user behavior in these widely deployed messaging paradigms. In this paper we discuss and examine implicit group messaging; an application-layer many-to-many messaging paradigm for delivering messages from publishers to specified groups of consumers. Such consumer groups are not addressed by explicit names, instead they are reached by describing the shared attributes or interests of consumers, forming easily defined implicit groups. Based on a 4 week experiment we analyze the characteristics of implicit groups and their usage. We find implicit group messaging workload to be similar to RSS in terms of group membership and update patterns; groups are typically small with few large examples and update rates vary from infrequent to more limited intervals.
{"title":"Analyzing implicit group messaging: A novel messaging paradigm for group-oriented content distribution","authors":"Neil Cowzer, P. Nixon","doi":"10.1109/GLOCOMW.2010.5700191","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700191","url":null,"abstract":"Publish-subscribe systems are well suited loosely decoupled nature of the web, resulting in the messaging paradigm gaining widespread adoption and being the subject of much research. Such research has focused primarily on architectures and filtering algorithms with little evidence of performance analysis or characterization of user behavior in these widely deployed messaging paradigms. In this paper we discuss and examine implicit group messaging; an application-layer many-to-many messaging paradigm for delivering messages from publishers to specified groups of consumers. Such consumer groups are not addressed by explicit names, instead they are reached by describing the shared attributes or interests of consumers, forming easily defined implicit groups. Based on a 4 week experiment we analyze the characteristics of implicit groups and their usage. We find implicit group messaging workload to be similar to RSS in terms of group membership and update patterns; groups are typically small with few large examples and update rates vary from infrequent to more limited intervals.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122465264","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700379
G. Aristomenopoulos, T. Kastrinogiannis, Z. Li, M. Wilson, M. G. Juan, A. Jose, Y. Li, V. Kaldanis, S. Papavassiliou
This paper presents the key designing principles and attributes of a novel autonomic architecture for enabling efficient mobility and QoS-aware resource management over an integrated IPv6-enabled heterogeneous wireless environment (CDMA cellular/WLAN). The proposed architecture is founded on Generic Autonomic Network Architecture (GANA), a generic framework for realizing autonomic networks introduced in EFIPSANS EC FP7 project. Emphasis is placed on describing the autonomic components of the architecture, illustrating their interactions and justifying their designing properties towards creating a concrete autonomic paradigm that aims at fulfilling 3GPP/LTE self-optimization vision.
{"title":"Autonomic mobility and resource management over an integrated wireless environment — A GANA oriented architecture","authors":"G. Aristomenopoulos, T. Kastrinogiannis, Z. Li, M. Wilson, M. G. Juan, A. Jose, Y. Li, V. Kaldanis, S. Papavassiliou","doi":"10.1109/GLOCOMW.2010.5700379","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700379","url":null,"abstract":"This paper presents the key designing principles and attributes of a novel autonomic architecture for enabling efficient mobility and QoS-aware resource management over an integrated IPv6-enabled heterogeneous wireless environment (CDMA cellular/WLAN). The proposed architecture is founded on Generic Autonomic Network Architecture (GANA), a generic framework for realizing autonomic networks introduced in EFIPSANS EC FP7 project. Emphasis is placed on describing the autonomic components of the architecture, illustrating their interactions and justifying their designing properties towards creating a concrete autonomic paradigm that aims at fulfilling 3GPP/LTE self-optimization vision.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122867064","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700332
Vatche Isahagian, I. Matta, J. Akinwumi
As the Internet has evolved and grown, an increasing number of nodes (hosts or autonomous systems) have become multihomed, i.e., a node is connected to more than one network. Multihoming can be viewed as a special case of mobility-as a node moves, it unsubscribes from one network and subscribes to another, which is akin to one interface becoming inactive and another active. The current Internet architecture has been facing significant challenges in effectively dealing with mobility (and consequently multihoming). The Recursive InterNetwork Architecture (RINA) [1] was recently proposed as a clean-slate solution to the current problems of the Internet. In this paper, we perform an average-case cost analysis to compare the mobility / multihoming support of RINA, against that of other approaches such as LISP and Mobile-IP. We also validate our analysis using simulation.
{"title":"On the cost of supporting mobility and multihoming","authors":"Vatche Isahagian, I. Matta, J. Akinwumi","doi":"10.1109/GLOCOMW.2010.5700332","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700332","url":null,"abstract":"As the Internet has evolved and grown, an increasing number of nodes (hosts or autonomous systems) have become multihomed, i.e., a node is connected to more than one network. Multihoming can be viewed as a special case of mobility-as a node moves, it unsubscribes from one network and subscribes to another, which is akin to one interface becoming inactive and another active. The current Internet architecture has been facing significant challenges in effectively dealing with mobility (and consequently multihoming). The Recursive InterNetwork Architecture (RINA) [1] was recently proposed as a clean-slate solution to the current problems of the Internet. In this paper, we perform an average-case cost analysis to compare the mobility / multihoming support of RINA, against that of other approaches such as LISP and Mobile-IP. We also validate our analysis using simulation.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123906375","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 : 2010-12-01DOI: 10.1109/GLOCOMW.2010.5700420
H. Şenol, E. Panayirci, H. Poor
This paper is concerned with the challenging and timely problem of channel estimation for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and very rapidly time varying channels. In OFDM systems operating over rapidly time-varying channels, the orthogonality between subcarriers is destroyed leading to inter-carrier interference (ICI) and resulting in an irreducible error floor. The band-limited, discrete cosine serial expansion of low-dimensionality is employed to represent the time-varying channel. In this way, the resulting reduced dimensional channel coefficients are estimated iteratively with tractable complexity and independently of the channel statistics. The algorithm is based on the expectation maximization-maximum a posteriori probability (EM-MAP) technique leading to a receiver structure that also yields the equalized output using the channel estimates. The pilot symbols are employed to estimate the initial coefficients effectively and unknown data symbols are averaged out in the algorithm in a non-data-aided fashion. It is shown that the computational complexity of the proposed algorithm to estimate the channel coefficients and to generate the equalized output as a by-product is ≃ O(N) per detected symbol, N being the number of OFDM subcarriers. Computational complexity as well as computer simulations carried out for the systems described in WiMAX and LTE standards indicate that it has significant performance and complexity advantages over existing suboptimal channel estimation and equalization algorithms proposed earlier in the literature.
{"title":"Joint channel estimation and equalization for OFDM based broadband communications in rapidly varying mobile channels","authors":"H. Şenol, E. Panayirci, H. Poor","doi":"10.1109/GLOCOMW.2010.5700420","DOIUrl":"https://doi.org/10.1109/GLOCOMW.2010.5700420","url":null,"abstract":"This paper is concerned with the challenging and timely problem of channel estimation for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and very rapidly time varying channels. In OFDM systems operating over rapidly time-varying channels, the orthogonality between subcarriers is destroyed leading to inter-carrier interference (ICI) and resulting in an irreducible error floor. The band-limited, discrete cosine serial expansion of low-dimensionality is employed to represent the time-varying channel. In this way, the resulting reduced dimensional channel coefficients are estimated iteratively with tractable complexity and independently of the channel statistics. The algorithm is based on the expectation maximization-maximum a posteriori probability (EM-MAP) technique leading to a receiver structure that also yields the equalized output using the channel estimates. The pilot symbols are employed to estimate the initial coefficients effectively and unknown data symbols are averaged out in the algorithm in a non-data-aided fashion. It is shown that the computational complexity of the proposed algorithm to estimate the channel coefficients and to generate the equalized output as a by-product is ≃ O(N) per detected symbol, N being the number of OFDM subcarriers. Computational complexity as well as computer simulations carried out for the systems described in WiMAX and LTE standards indicate that it has significant performance and complexity advantages over existing suboptimal channel estimation and equalization algorithms proposed earlier in the literature.","PeriodicalId":232205,"journal":{"name":"2010 IEEE Globecom Workshops","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125526543","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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