Pub Date : 2000-12-17DOI: 10.1109/ICPWC.2000.905851
A. Dawood, M. M. Oo, K. Ahmed, N. Rajatheva
Channel assignment is the key to spectrum management. In this paper, the channel assignment problem is modeled as a graph coloring formulation. The task of assigning a limited number of channels to transmitters under a set of constraints in an efficient way is an NP-complete optimization problem. We apply a powerful metaheuristic search algorithm, namely a simulated annealing algorithm together with a sequential algorithm, to tackle this type of problem. In order to evaluate the performance of the methodology, the algorithm is tested on a number of benchmark problems and the results are compared with the existing ones for the same set of constraints. It is found that the results obtained by our approach are comparable to those obtained by existing methods.
{"title":"Efficient channel assignment algorithm under cochannel and adjacent channel interference constraint","authors":"A. Dawood, M. M. Oo, K. Ahmed, N. Rajatheva","doi":"10.1109/ICPWC.2000.905851","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905851","url":null,"abstract":"Channel assignment is the key to spectrum management. In this paper, the channel assignment problem is modeled as a graph coloring formulation. The task of assigning a limited number of channels to transmitters under a set of constraints in an efficient way is an NP-complete optimization problem. We apply a powerful metaheuristic search algorithm, namely a simulated annealing algorithm together with a sequential algorithm, to tackle this type of problem. In order to evaluate the performance of the methodology, the algorithm is tested on a number of benchmark problems and the results are compared with the existing ones for the same set of constraints. It is found that the results obtained by our approach are comparable to those obtained by existing methods.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115459417","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905810
P. Shamain, L. Milstein
Wideband wireless communication systems based on the code division multiple access (CDMA) technique are increasingly being used for data communication. Initial acquisition (synchronization) in such systems employing random (long) spreading codes has been studied, and the corresponding optimal receiver has been designed. We investigate here initial acquisition when the system employs deterministic (short) spreading codes. We derive the optimum receiver that accounts for the deterministic nature of the spreading codes. This receiver lends itself to a simple implementation, unlike the optimal receiver for the long spreading codes, which involves Bessel functions. Finally, we show that using our optimum receiver with lower processing gain (and hence with reduced complexity), we can obtain performance comparable to that of a system with higher processing gain.
{"title":"Acquisition of direct sequence spread spectrum signals in frequency selective Rayleigh and Ricean channels","authors":"P. Shamain, L. Milstein","doi":"10.1109/ICPWC.2000.905810","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905810","url":null,"abstract":"Wideband wireless communication systems based on the code division multiple access (CDMA) technique are increasingly being used for data communication. Initial acquisition (synchronization) in such systems employing random (long) spreading codes has been studied, and the corresponding optimal receiver has been designed. We investigate here initial acquisition when the system employs deterministic (short) spreading codes. We derive the optimum receiver that accounts for the deterministic nature of the spreading codes. This receiver lends itself to a simple implementation, unlike the optimal receiver for the long spreading codes, which involves Bessel functions. Finally, we show that using our optimum receiver with lower processing gain (and hence with reduced complexity), we can obtain performance comparable to that of a system with higher processing gain.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114525731","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905761
R. Vishwakarma, K. Shanmugan
Transmit diversity schemes employ several antennas at the cellular base station to improve the forward link transmission performance (throughput, range, capacity and quality) without increasing the complexity of the mobile station. This paper attempts to evaluate the forward link performance improvement using different transmit diversity schemes by means of computer simulation. The schemes considered are space-time transmit diversity (STTD) and feedback mode transmit diversity (FBTD) proposed in a third generation (3G) WCDMA system. The effect of noisy channel estimates, due to imperfect channel estimation, and of imperfect closed loop power control, due to imperfect signal to interference ratio (SIR) estimation, on the performance is analyzed under different channel conditions and mobile velocities. The channel environments considered in the simulations are single ray Rayleigh fading, vehicular channel and pedestrian channel. It is observed that, with power control, the difference in the performance of ND, STTD and FBTD is not significant (around 1 dB to 2 dB) at high user velocities (>120 kmph). It is hence concluded that that with SIR based closed loop power control and imperfect channel estimation, diversity gains are not significant in the downlink of WCDMA system.
{"title":"Performance analysis of transmit antenna diversity in 3G WCDMA system","authors":"R. Vishwakarma, K. Shanmugan","doi":"10.1109/ICPWC.2000.905761","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905761","url":null,"abstract":"Transmit diversity schemes employ several antennas at the cellular base station to improve the forward link transmission performance (throughput, range, capacity and quality) without increasing the complexity of the mobile station. This paper attempts to evaluate the forward link performance improvement using different transmit diversity schemes by means of computer simulation. The schemes considered are space-time transmit diversity (STTD) and feedback mode transmit diversity (FBTD) proposed in a third generation (3G) WCDMA system. The effect of noisy channel estimates, due to imperfect channel estimation, and of imperfect closed loop power control, due to imperfect signal to interference ratio (SIR) estimation, on the performance is analyzed under different channel conditions and mobile velocities. The channel environments considered in the simulations are single ray Rayleigh fading, vehicular channel and pedestrian channel. It is observed that, with power control, the difference in the performance of ND, STTD and FBTD is not significant (around 1 dB to 2 dB) at high user velocities (>120 kmph). It is hence concluded that that with SIR based closed loop power control and imperfect channel estimation, diversity gains are not significant in the downlink of WCDMA system.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115435565","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905908
A. Kumar, Ritesh Sood, H. Saran, R. Shorey
An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any existing network infrastructure or centralized administration. Various ad-hoc routing protocols have been proposed in the literature, such as destination sequenced distance vector (DSDV), ad-hoc on-demand distance vector (AODV) and dynamic source routing (DSR). TCP/IP is the most widely used transport protocol for data services such as file transfer (FTP), e-mail and WWW browsing. For this reason, its use over mobile ad-hoc networks is a certainty. TCP, primarily designed for wireline networks, faces performance degradation when applied to the ad-hoc scenario. Earlier work focussed on comparing the performance of different routing protocols with a single TCP connection. In this paper, we study the performance of multiple TCP connections over various ad-hoc routing protocols. The performance metrics of interest are the TCP throughput and the coefficient of fairness.
{"title":"Performance of multiple TCP connections over different routing protocols in mobile ad-hoc networks","authors":"A. Kumar, Ritesh Sood, H. Saran, R. Shorey","doi":"10.1109/ICPWC.2000.905908","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905908","url":null,"abstract":"An ad hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the use of any existing network infrastructure or centralized administration. Various ad-hoc routing protocols have been proposed in the literature, such as destination sequenced distance vector (DSDV), ad-hoc on-demand distance vector (AODV) and dynamic source routing (DSR). TCP/IP is the most widely used transport protocol for data services such as file transfer (FTP), e-mail and WWW browsing. For this reason, its use over mobile ad-hoc networks is a certainty. TCP, primarily designed for wireline networks, faces performance degradation when applied to the ad-hoc scenario. Earlier work focussed on comparing the performance of different routing protocols with a single TCP connection. In this paper, we study the performance of multiple TCP connections over various ad-hoc routing protocols. The performance metrics of interest are the TCP throughput and the coefficient of fairness.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123431981","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905911
F. Anjum
In this paper, we concentrate on one aspect of information system security, namely that of intrusion tolerance. An intrusion tolerant system is one that continues to function correctly and provide the intended user services in a timely manner even in the face of an information attack. In this paper we concentrate on a technique called fragmentation-redundancy-scattering and investigate how this technique can be used in a mobile environment. We also provide different schemes towards ensuring intrusion tolerance in a mobile system.
{"title":"Intrusion tolerance schemes to facilitate mobile e-commerce","authors":"F. Anjum","doi":"10.1109/ICPWC.2000.905911","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905911","url":null,"abstract":"In this paper, we concentrate on one aspect of information system security, namely that of intrusion tolerance. An intrusion tolerant system is one that continues to function correctly and provide the intended user services in a timely manner even in the face of an information attack. In this paper we concentrate on a technique called fragmentation-redundancy-scattering and investigate how this technique can be used in a mobile environment. We also provide different schemes towards ensuring intrusion tolerance in a mobile system.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121561628","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905778
A. Das, A. Ghose, V. Gupta, Ashu Razdan, H. Saran, R. Shorey
Bluetooth is a universal short-range radio link for high-speed wireless communications. One critical issue in wireless communication systems is the efficient encoding of data to ensure correctness in the presence of noise and multipath fading. Bluetooth provides two techniques to handle link-level transmission errors: automatic repeat request (ARQ) and forward error correction (FEC). We propose an adaptive hybrid ARQ/FEC scheme to enhance the data throughput over Bluetooth based on observed error rates. Simulation results show that the adaptive ARQ/FEC coding scheme significantly improves the data performance of Bluetooth wireless communication systems compared to stationary ARQ/FEC schemes which do not take the channel conditions into account.
{"title":"Adaptive link-level error recovery mechanisms in Bluetooth","authors":"A. Das, A. Ghose, V. Gupta, Ashu Razdan, H. Saran, R. Shorey","doi":"10.1109/ICPWC.2000.905778","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905778","url":null,"abstract":"Bluetooth is a universal short-range radio link for high-speed wireless communications. One critical issue in wireless communication systems is the efficient encoding of data to ensure correctness in the presence of noise and multipath fading. Bluetooth provides two techniques to handle link-level transmission errors: automatic repeat request (ARQ) and forward error correction (FEC). We propose an adaptive hybrid ARQ/FEC scheme to enhance the data throughput over Bluetooth based on observed error rates. Simulation results show that the adaptive ARQ/FEC coding scheme significantly improves the data performance of Bluetooth wireless communication systems compared to stationary ARQ/FEC schemes which do not take the channel conditions into account.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121801495","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905854
Jitendra Tugnait
A code-constrained inverse filter criteria-based approach is presented for blind detection of asynchronous short-code DS-CDMA (direct sequence code division multiple access) signals in multipath channels. Only the spreading code of the desired user is assumed to be known; its transmission delay may be unknown. We focus on maximization of the normalized fourth cumulant of inverse filtered (equalized) data with respect to the equalizer coefficients subject to the equalizer lying in a subspace associated with the desired user's code sequence. Constrained maximization leads to extraction of the desired user's signal whereas unconstrained maximization leads to the extraction of any one of the active users. A simulation example is provided.
{"title":"On blind detection of asynchronous DS-CDMA signals in multipath channels","authors":"Jitendra Tugnait","doi":"10.1109/ICPWC.2000.905854","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905854","url":null,"abstract":"A code-constrained inverse filter criteria-based approach is presented for blind detection of asynchronous short-code DS-CDMA (direct sequence code division multiple access) signals in multipath channels. Only the spreading code of the desired user is assumed to be known; its transmission delay may be unknown. We focus on maximization of the normalized fourth cumulant of inverse filtered (equalized) data with respect to the equalizer coefficients subject to the equalizer lying in a subspace associated with the desired user's code sequence. Constrained maximization leads to extraction of the desired user's signal whereas unconstrained maximization leads to the extraction of any one of the active users. A simulation example is provided.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123139929","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905781
Chengyang Li, S. Roy
A new blind MMSE detection for multi-carrier CDMA (MC-CDMA) over intersymbol interference (ISI) channels is proposed. The presence of virtual carriers is exploited to give a subspace based blind channel estimator followed by a linear MMSE equalizer. The proposed detector is attractive for its higher spectral efficiency, which is achieved by the elimination of cyclic prefix and training sequences. The complexity of the full dimension subspace detection can be reduced at the cost of some performance degradation. Representative results are provided to show the performance-complexity tradeoffs.
{"title":"Subspace based detection in MC-CDMA over dispersive channel","authors":"Chengyang Li, S. Roy","doi":"10.1109/ICPWC.2000.905781","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905781","url":null,"abstract":"A new blind MMSE detection for multi-carrier CDMA (MC-CDMA) over intersymbol interference (ISI) channels is proposed. The presence of virtual carriers is exploited to give a subspace based blind channel estimator followed by a linear MMSE equalizer. The proposed detector is attractive for its higher spectral efficiency, which is achieved by the elimination of cyclic prefix and training sequences. The complexity of the full dimension subspace detection can be reduced at the cost of some performance degradation. Representative results are provided to show the performance-complexity tradeoffs.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114457999","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905828
K. Tong, M. Hamdi, K. Ben Letaief
A multiple-cell wireless TDMA network is considered. In particular, we extend our previous work [1] for a single-cell wireless network in which multiple delay classes were mathematically analyzed and proved to be independent of the work-conserving scheduling algorithm used. Our extension includes the incorporation of a handoff model to provide an integration between call-level and packet-level quality-of-service (QoS) in a wireless TDMA environment. Throughout extensive networking parameters, we verify the usefulness of our model in terms of its capability of determining the achievable QoS guarantees in a wireless environment.
{"title":"Achievable quality-of-service guarantees in wireless communication environments","authors":"K. Tong, M. Hamdi, K. Ben Letaief","doi":"10.1109/ICPWC.2000.905828","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905828","url":null,"abstract":"A multiple-cell wireless TDMA network is considered. In particular, we extend our previous work [1] for a single-cell wireless network in which multiple delay classes were mathematically analyzed and proved to be independent of the work-conserving scheduling algorithm used. Our extension includes the incorporation of a handoff model to provide an integration between call-level and packet-level quality-of-service (QoS) in a wireless TDMA environment. Throughout extensive networking parameters, we verify the usefulness of our model in terms of its capability of determining the achievable QoS guarantees in a wireless environment.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"372 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132837685","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 : 2000-12-17DOI: 10.1109/ICPWC.2000.905832
M.M. Sekhar, K. Sivarajan
A new approach for channel assignment in packet radio networks is presented. To arrive at this: (1) we show the difficulty with the traditional graph coloring method for link scheduling; (2) an algorithm for generating maximal independent sets of links is presented; (3) the importance of combined routing and scheduling is shown and an LP problem is formulated for combined routing and scheduling.
{"title":"Routing and scheduling in packet radio networks","authors":"M.M. Sekhar, K. Sivarajan","doi":"10.1109/ICPWC.2000.905832","DOIUrl":"https://doi.org/10.1109/ICPWC.2000.905832","url":null,"abstract":"A new approach for channel assignment in packet radio networks is presented. To arrive at this: (1) we show the difficulty with the traditional graph coloring method for link scheduling; (2) an algorithm for generating maximal independent sets of links is presented; (3) the importance of combined routing and scheduling is shown and an LP problem is formulated for combined routing and scheduling.","PeriodicalId":260472,"journal":{"name":"2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116558860","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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