Pub Date : 2005-05-02DOI: 10.1109/ICC.2003.1204405
A. Swaminathan, D. Noneaker
In this paper we examine a simple method to improve the performance of serial, matched-filter acquisition indirect-sequence spread-spectrum packet radio communications. Each packet transmission includes an acquisition preamble, and the preamble sequence is changed at the boundaries of predefined time epochs based on a pseudorandom sequence generator. It is shown in previous work that the presence of an IF filter and the characteristics of the AGC subsystem, lead to a probability of not acquiring that is a non-monotonic function of the signal-to-noise ratio if the acquisition algorithm uses a threshold-crossing detector with a fixed threshold. The acquisition algorithm presented in this paper employs an estimator to adaptively select the acquisition threshold. It is shown that this technique reduces the severity of the non-monotonicity and substantially improves the acquisition performance.
{"title":"A technique to improve the performance of serial, matched-filter acquisition in direct-sequence spread-spectrum packet radio communications","authors":"A. Swaminathan, D. Noneaker","doi":"10.1109/ICC.2003.1204405","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204405","url":null,"abstract":"In this paper we examine a simple method to improve the performance of serial, matched-filter acquisition indirect-sequence spread-spectrum packet radio communications. Each packet transmission includes an acquisition preamble, and the preamble sequence is changed at the boundaries of predefined time epochs based on a pseudorandom sequence generator. It is shown in previous work that the presence of an IF filter and the characteristics of the AGC subsystem, lead to a probability of not acquiring that is a non-monotonic function of the signal-to-noise ratio if the acquisition algorithm uses a threshold-crossing detector with a fixed threshold. The acquisition algorithm presented in this paper employs an estimator to adaptively select the acquisition threshold. It is shown that this technique reduces the severity of the non-monotonicity and substantially improves the acquisition performance.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130573190","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204580
Frederick K. H. Lee, Kitty K. Y. Wong, P. McLane
A novel coding and turbo equalization scheme for sparse multipath channels is presented in this paper. A burst-error-correcting convolutional code, which coding and interleaving via a sparse encoder and a convolutional interleaver, is selected as the channel code. A previously-proposed parallel-trellis framework is adopted for implementing the maximum a posteriori (MAP) equalizer and decoder in the turbo equalizer. Such a system exhibits a similar level of performance to a conventional system using a random-error-correcting convolutional code together with a row /column (R/C) or random block interleaver. Yet, the proposed system has the advantages of low latency and low memory requirements when compared to those conventional systems. This is due to (i) the elimination of the block-type interleavers and deinterleavers and (ii) the parallelism achieved in the turbo equalizer. One disadvantage of the proposed system is to decrease in throughput, as more tail symbols are required for proper termination of all sub-trellises in the decoder. Extension of the proposed system to turbo codes is considered. Also, the effect of prefiltering on a nonminimum-phase, high definition television (HDTV) channel is examined. Results indicate that using the feedforward filter (FFF) of a nonuniformly-spaced decision feedback equalizer (NU-DFE) performs almost as good as using one with a large number of uniformly-spaced taps. However, far fewer computations are needed to find the optimum tap values of the sparse prefilter.
{"title":"Parallel-trellis turbo equalizers for sparse-coded transmission over sparse multipath channels","authors":"Frederick K. H. Lee, Kitty K. Y. Wong, P. McLane","doi":"10.1109/ICC.2003.1204580","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204580","url":null,"abstract":"A novel coding and turbo equalization scheme for sparse multipath channels is presented in this paper. A burst-error-correcting convolutional code, which coding and interleaving via a sparse encoder and a convolutional interleaver, is selected as the channel code. A previously-proposed parallel-trellis framework is adopted for implementing the maximum a posteriori (MAP) equalizer and decoder in the turbo equalizer. Such a system exhibits a similar level of performance to a conventional system using a random-error-correcting convolutional code together with a row /column (R/C) or random block interleaver. Yet, the proposed system has the advantages of low latency and low memory requirements when compared to those conventional systems. This is due to (i) the elimination of the block-type interleavers and deinterleavers and (ii) the parallelism achieved in the turbo equalizer. One disadvantage of the proposed system is to decrease in throughput, as more tail symbols are required for proper termination of all sub-trellises in the decoder. Extension of the proposed system to turbo codes is considered. Also, the effect of prefiltering on a nonminimum-phase, high definition television (HDTV) channel is examined. Results indicate that using the feedforward filter (FFF) of a nonuniformly-spaced decision feedback equalizer (NU-DFE) performs almost as good as using one with a large number of uniformly-spaced taps. However, far fewer computations are needed to find the optimum tap values of the sparse prefilter.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115128367","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204413
J. Giese, M. Skoglund
We consider the design of space-time constellations for communication over frequency-selective fading channels where neither the transmitter nor the receiver has any channel state information. The design is based on the asymptotic union bound on error probability as design criterion and the optimization is carried out using a gradient search algorithm. Full multi-antenna multipath diversity gains are demonstrated to be achieved by the designed codes. Compared to other constellations proposed by Hochwald et al., power savings of up to 2 dB are shown to be possible.
{"title":"Space-time constellations for unknown frequency-selective channels","authors":"J. Giese, M. Skoglund","doi":"10.1109/ICC.2003.1204413","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204413","url":null,"abstract":"We consider the design of space-time constellations for communication over frequency-selective fading channels where neither the transmitter nor the receiver has any channel state information. The design is based on the asymptotic union bound on error probability as design criterion and the optimization is carried out using a gradient search algorithm. Full multi-antenna multipath diversity gains are demonstrated to be achieved by the designed codes. Compared to other constellations proposed by Hochwald et al., power savings of up to 2 dB are shown to be possible.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121831487","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204539
G. Cuypers, K. Vanbleu, G. Ysebaert, M. Moonen, P. Vandaele
Discrete multitone (DMT) offers an elegant way to achieve high capacity, dividing the spectrum into small bands and processing these individually. The per tone equalizer (PTEQ) optimizes the capacity for each band individually, thus optimizing the whole. However, it provides little protection against narrow band radio frequency interference (RFI), being spread over all tones because of the high side lobes of the DFT filter band used in the receiver. The use of windowing functions limits this noise spreading, but is difficult to combine with the PTEQ. This paper describes a method to combine the PTEQ with a raised cosine window, while keeping the complexity reasonable. Extensions to other windowing functions are also given.
{"title":"Combining raised cosine windowing and per tone equalization for RFI mitigation in DMT receivers","authors":"G. Cuypers, K. Vanbleu, G. Ysebaert, M. Moonen, P. Vandaele","doi":"10.1109/ICC.2003.1204539","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204539","url":null,"abstract":"Discrete multitone (DMT) offers an elegant way to achieve high capacity, dividing the spectrum into small bands and processing these individually. The per tone equalizer (PTEQ) optimizes the capacity for each band individually, thus optimizing the whole. However, it provides little protection against narrow band radio frequency interference (RFI), being spread over all tones because of the high side lobes of the DFT filter band used in the receiver. The use of windowing functions limits this noise spreading, but is difficult to combine with the PTEQ. This paper describes a method to combine the PTEQ with a raised cosine window, while keeping the complexity reasonable. Extensions to other windowing functions are also given.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"483 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116929430","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 : 2003-05-11DOI: 10.1109/ICC.2003.1203941
H. Cho, Jae Yong Lee, Byungchul Kim
This paper proposes two multi-path constraint-based routing algorithms for Internet traffic engineering using MPLS. In a normal constraint-based shortest path first (CSPF) routing algorithm, there is a high probability that it cannot find a feasible path through networks for a large bandwidth constraint, which is one of the most important constraints for traffic engineering. The proposed algorithms can divide the bandwidth constraint into two or more seconds and find a constrained path for each subconstraint. Extensive simulations show that they enhance the success probability of path setup and the utilization of network resources.
{"title":"Multi-path constraint-based routing algorithms for MPLS traffic engineering","authors":"H. Cho, Jae Yong Lee, Byungchul Kim","doi":"10.1109/ICC.2003.1203941","DOIUrl":"https://doi.org/10.1109/ICC.2003.1203941","url":null,"abstract":"This paper proposes two multi-path constraint-based routing algorithms for Internet traffic engineering using MPLS. In a normal constraint-based shortest path first (CSPF) routing algorithm, there is a high probability that it cannot find a feasible path through networks for a large bandwidth constraint, which is one of the most important constraints for traffic engineering. The proposed algorithms can divide the bandwidth constraint into two or more seconds and find a constrained path for each subconstraint. Extensive simulations show that they enhance the success probability of path setup and the utilization of network resources.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117261312","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204184
Li Wang, Yu-Kwong Kwok, W. Lau, V. Lau
Multiple access control (MAC) of the uplink in a wireless mobile computing system is one of the most important resource allocation problems in that the response time and throughput of user applications (e.g., wireless web surfing) are critically affected by the efficiency of the MAC protocol. Compared with a traditional MAC problem (e.g., wireline Ethernet), there are two important new challenges in a modern wireless network: (1) multimedia data with diverse traffic requirements are involved; and (2) the wireless channel has a time-varying quality for each user. Furthermore, a more prominent user requirement is fairness among different users, possibly, with different traffic demands. While some protocols have been suggested to handle multimedia data and/or tackling the time-varying channel, there are a number of drawbacks in these existing protocols. The most notable drawback is that the channel model is rather unrealistic - just using a two state Markov chain instead of relying on accurate models of multipath fading and shadowing effects. Another common deficiency is that fairness is ignored. In this paper, we propose to use a new notion of fairness that can capture a realistic channel model, and to integrate a fair queuing scheduling algorithm in a MAC protocol to optimize performance while maintaining fairness among users regardless of their channel states and data types.
{"title":"On channel-adaptive fair multiple access control","authors":"Li Wang, Yu-Kwong Kwok, W. Lau, V. Lau","doi":"10.1109/ICC.2003.1204184","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204184","url":null,"abstract":"Multiple access control (MAC) of the uplink in a wireless mobile computing system is one of the most important resource allocation problems in that the response time and throughput of user applications (e.g., wireless web surfing) are critically affected by the efficiency of the MAC protocol. Compared with a traditional MAC problem (e.g., wireline Ethernet), there are two important new challenges in a modern wireless network: (1) multimedia data with diverse traffic requirements are involved; and (2) the wireless channel has a time-varying quality for each user. Furthermore, a more prominent user requirement is fairness among different users, possibly, with different traffic demands. While some protocols have been suggested to handle multimedia data and/or tackling the time-varying channel, there are a number of drawbacks in these existing protocols. The most notable drawback is that the channel model is rather unrealistic - just using a two state Markov chain instead of relying on accurate models of multipath fading and shadowing effects. Another common deficiency is that fairness is ignored. In this paper, we propose to use a new notion of fairness that can capture a realistic channel model, and to integrate a fair queuing scheduling algorithm in a MAC protocol to optimize performance while maintaining fairness among users regardless of their channel states and data types.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":" 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120830569","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204194
H. Pham, B. Lavery
This paper presents performance data for a new hybrid routing method (HRM) for IP network traffic engineering. In this method, the major traffic streams between some source/destination pairs is routed via MPLS constraint based routing, while the remaining traffic is routed via conventional IGP routing. When Internet traffic is heavy-tailed distributed, consisting of a few "elephant" and many "mice" flows, our traffic engineering results indicate that our HRM normally needs just a small number of tunnels to achieve a network performance that is comparable to that of fully meshed MPLS network. The method has been used to implement a HRM traffic engineering tool. The tool enables network operators to visualize and manage traffic to avoid congestion, as well as to decide where to place MPLS routers and tunnels.
{"title":"Hybrid routing for scalable IP/MPLS traffic engineering","authors":"H. Pham, B. Lavery","doi":"10.1109/ICC.2003.1204194","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204194","url":null,"abstract":"This paper presents performance data for a new hybrid routing method (HRM) for IP network traffic engineering. In this method, the major traffic streams between some source/destination pairs is routed via MPLS constraint based routing, while the remaining traffic is routed via conventional IGP routing. When Internet traffic is heavy-tailed distributed, consisting of a few \"elephant\" and many \"mice\" flows, our traffic engineering results indicate that our HRM normally needs just a small number of tunnels to achieve a network performance that is comparable to that of fully meshed MPLS network. The method has been used to implement a HRM traffic engineering tool. The tool enables network operators to visualize and manage traffic to avoid congestion, as well as to decide where to place MPLS routers and tunnels.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127123872","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204248
Xinyan Zhang, G. Song, Qian Zhang, Wenwu Zhu, Zhensheng Zhang
In this paper, we propose a performance analysis model to study the reach-ability in unstructured overlay networks. Given a node's degree distribution and a network size, n, the model describes the flooding query pattern in a P2P network accurately. Also, we prove that in such an overlay network, the average distance between any two hosts is limited by O(log N). This model is simple and accurate, and therefore is a very useful tool in exploring many properties of massive overlay networks. It can be applied to P2P based content distribution networks and ad hoc wireless networks, for example.
{"title":"Performance analysis in unstructured overlays","authors":"Xinyan Zhang, G. Song, Qian Zhang, Wenwu Zhu, Zhensheng Zhang","doi":"10.1109/ICC.2003.1204248","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204248","url":null,"abstract":"In this paper, we propose a performance analysis model to study the reach-ability in unstructured overlay networks. Given a node's degree distribution and a network size, n, the model describes the flooding query pattern in a P2P network accurately. Also, we prove that in such an overlay network, the average distance between any two hosts is limited by O(log N). This model is simple and accurate, and therefore is a very useful tool in exploring many properties of massive overlay networks. It can be applied to P2P based content distribution networks and ad hoc wireless networks, for example.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127497300","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204051
L. Lampe, Roman Tzschoppe, J. Huber, R. Schober
The combination of continuous phase modulation (CPM) with direct-sequence code-division multiple access (DS-CDMA) for multiuser transmission over the additive white Gaussian noise channel is discussed. Concentrating on the important special case of generalized minimum-shift keying, particularly simple receiver structures are obtained. To emphasize on low complexity, noncoherent reception is proposed and appropriate transmitter and receiver designs are provided. The application of reduced-state noncoherent sequence detection and noncoherent filter adaptation ensures high power efficiency and robustness against channel phase variations. Simulation results confirm that the chosen approach of CPM for DS-CDMA achieves high performance with very moderate complexity.
{"title":"Noncoherent continuous-phase modulation for DS-CDMA","authors":"L. Lampe, Roman Tzschoppe, J. Huber, R. Schober","doi":"10.1109/ICC.2003.1204051","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204051","url":null,"abstract":"The combination of continuous phase modulation (CPM) with direct-sequence code-division multiple access (DS-CDMA) for multiuser transmission over the additive white Gaussian noise channel is discussed. Concentrating on the important special case of generalized minimum-shift keying, particularly simple receiver structures are obtained. To emphasize on low complexity, noncoherent reception is proposed and appropriate transmitter and receiver designs are provided. The application of reduced-state noncoherent sequence detection and noncoherent filter adaptation ensures high power efficiency and robustness against channel phase variations. Simulation results confirm that the chosen approach of CPM for DS-CDMA achieves high performance with very moderate complexity.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125871985","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 : 2003-05-11DOI: 10.1109/ICC.2003.1204117
T. Bertozzi, D. L. Ruyet, G. Rigal, H. V. Thien
Instead of reduced-state decision-feedback sequence estimation (DFSE) equalization which is the state-of-the-art solution for the complexity reduction of the full-state Viterbi decoder over a multipath fading channel, we propose a new reduced complexity maximum likelihood sequence detector (MLSD) based on the particle filtering technique. The computational complexity of this new detector is adapted according to the signal-to-noise ratio. Compared to the DFSE detector the particle detector offers a better trade-off between performance and computational complexity.
{"title":"MLSE receiver using the particle filtering over a multipath fading channel","authors":"T. Bertozzi, D. L. Ruyet, G. Rigal, H. V. Thien","doi":"10.1109/ICC.2003.1204117","DOIUrl":"https://doi.org/10.1109/ICC.2003.1204117","url":null,"abstract":"Instead of reduced-state decision-feedback sequence estimation (DFSE) equalization which is the state-of-the-art solution for the complexity reduction of the full-state Viterbi decoder over a multipath fading channel, we propose a new reduced complexity maximum likelihood sequence detector (MLSD) based on the particle filtering technique. The computational complexity of this new detector is adapted according to the signal-to-noise ratio. Compared to the DFSE detector the particle detector offers a better trade-off between performance and computational complexity.","PeriodicalId":165440,"journal":{"name":"IEEE International Conference on Communications, 2003. ICC '03.","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126102022","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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