Pub Date : 2008-12-01DOI: 10.1109/ATNAC.2008.4783313
D. F. Cardoso, F. D. Backx, R. Sampaio-Neto
This work investigates the problem of uplink blind channel estimation in zero padded multi carrier direct sequence code division multiple access (MC-DS/CDMA-ZP). Using only the spreading code of the user of interest, our method explores the orthogonality of the signal and noise subspaces in conjunction with power techniques to estimate the channel state information (CSI) from the received data sequence. We also present an improved channel estimator that relies on the assumption that all the relevant multipath components of the channel impulse response lie within the guard interval duration. Simulations of mean square error and bit error rate performances demonstrate the robustness of the proposed scheme, and for moderate-to-high signal to noise ratios the presented method achieves performance comparable to existing subspace techniques but at a softer computational cost.
{"title":"Alternative Subspace Method for Improved Blind Channel Estimation in Uplink Zero Padded MC-DS/CDMA Systems","authors":"D. F. Cardoso, F. D. Backx, R. Sampaio-Neto","doi":"10.1109/ATNAC.2008.4783313","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783313","url":null,"abstract":"This work investigates the problem of uplink blind channel estimation in zero padded multi carrier direct sequence code division multiple access (MC-DS/CDMA-ZP). Using only the spreading code of the user of interest, our method explores the orthogonality of the signal and noise subspaces in conjunction with power techniques to estimate the channel state information (CSI) from the received data sequence. We also present an improved channel estimator that relies on the assumption that all the relevant multipath components of the channel impulse response lie within the guard interval duration. Simulations of mean square error and bit error rate performances demonstrate the robustness of the proposed scheme, and for moderate-to-high signal to noise ratios the presented method achieves performance comparable to existing subspace techniques but at a softer computational cost.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121970651","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783333
Johannes G̈obel, A. Krzesinski
Ad hoc networks are self-configuring networks of mobile nodes, connected by wireless links. Suppose each mobile node can make observations within a circular area of radius robs centred on its own location. The area coverage of the network is defined as the total area observed by the mobile nodes. We investigate a distributed scalable method based on local interactions with minimal sensing and low computational cost whereby the nodes move autonomously (self-deployment) in order to maximise the coverage of the network, while at the same time ensuring that the mobile nodes do not move so far away from each other (thus trivially maximising the coverage) that they become disconnected. Certain nodes may be instructed to move to specified locations. These guide nodes induce a correlated movement of groups of nodes which follow the guide nodes and establish maximal coverage in the specified locations. Simulation results demonstrate the coverage achieved by a group of 100 nodes when moving on an unbounded plane (optional guide nodes induce a collective motion to areas of interest) and when moving on a bounded plane with barriers or hills.
{"title":"A Model of Autonomous Motion in Ad Hoc Networks to Maximise Area Coverage","authors":"Johannes G̈obel, A. Krzesinski","doi":"10.1109/ATNAC.2008.4783333","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783333","url":null,"abstract":"Ad hoc networks are self-configuring networks of mobile nodes, connected by wireless links. Suppose each mobile node can make observations within a circular area of radius robs centred on its own location. The area coverage of the network is defined as the total area observed by the mobile nodes. We investigate a distributed scalable method based on local interactions with minimal sensing and low computational cost whereby the nodes move autonomously (self-deployment) in order to maximise the coverage of the network, while at the same time ensuring that the mobile nodes do not move so far away from each other (thus trivially maximising the coverage) that they become disconnected. Certain nodes may be instructed to move to specified locations. These guide nodes induce a correlated movement of groups of nodes which follow the guide nodes and establish maximal coverage in the specified locations. Simulation results demonstrate the coverage achieved by a group of 100 nodes when moving on an unbounded plane (optional guide nodes induce a collective motion to areas of interest) and when moving on a bounded plane with barriers or hills.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126029909","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783312
In Jun Park, Tong-sok Kim, Y. C. Kim
In iterated product of single parity check (SPC) codes, weight distribution is an important factor for the performance against transmission errors. A product code with Gaussian weight distribution should have a good performance. We present a closed-form solution for the weight distribution of a recursive SPC product code. We show that the code weights for this code are symmetrically distributed at (N plusmn radic(N)/2), where N is the full-length of a codeword. Though this code does not have a Gaussian weight distribution, it has better performance than conventional product codes. When soft-output iterative decoding is applied, the performance is away from the Shannon capacity limit by only 0.95 dB. Hence, we conclude that Gaussian weight distribution is not a necessary condition for a good performance.
{"title":"A Recursive Single Parity Check Product Code with Non-Gaussian Fixed Weight Distribution","authors":"In Jun Park, Tong-sok Kim, Y. C. Kim","doi":"10.1109/ATNAC.2008.4783312","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783312","url":null,"abstract":"In iterated product of single parity check (SPC) codes, weight distribution is an important factor for the performance against transmission errors. A product code with Gaussian weight distribution should have a good performance. We present a closed-form solution for the weight distribution of a recursive SPC product code. We show that the code weights for this code are symmetrically distributed at (N plusmn radic(N)/2), where N is the full-length of a codeword. Though this code does not have a Gaussian weight distribution, it has better performance than conventional product codes. When soft-output iterative decoding is applied, the performance is away from the Shannon capacity limit by only 0.95 dB. Hence, we conclude that Gaussian weight distribution is not a necessary condition for a good performance.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127042042","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783300
M. Farsinejad, M. Analoui
In this paper we introduce an efficient genetic algorithm based voice activity detection (GA-VAD) algorithm. The inputs for GA-VAD are zero-crossing difference and a new feature that is extracted from signal envelope parameter, called MULSE (multiplication of upper and lower signal envelope). The voice activity decision is obtained using a Threshold algorithm with additional decision smoothing. The key advantage of this method is its simple implementation and its low computational complexity and introducing a new simple and efficient feature, MULSE, for solving the VAD problem. The MULSE parameter could be appropriate substitution for energy parameter in VAD problems. The GA-based VAD algorithm (GA-VAD) is evaluated using the Timit database. It is shown that the GA-VAD achieves better performance than G. 729 Annex B at any noise level with a high artificial-to-intelligence ratio.
{"title":"A New Robust Voice Activity Detection method based on Genetic Algorithm","authors":"M. Farsinejad, M. Analoui","doi":"10.1109/ATNAC.2008.4783300","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783300","url":null,"abstract":"In this paper we introduce an efficient genetic algorithm based voice activity detection (GA-VAD) algorithm. The inputs for GA-VAD are zero-crossing difference and a new feature that is extracted from signal envelope parameter, called MULSE (multiplication of upper and lower signal envelope). The voice activity decision is obtained using a Threshold algorithm with additional decision smoothing. The key advantage of this method is its simple implementation and its low computational complexity and introducing a new simple and efficient feature, MULSE, for solving the VAD problem. The MULSE parameter could be appropriate substitution for energy parameter in VAD problems. The GA-based VAD algorithm (GA-VAD) is evaluated using the Timit database. It is shown that the GA-VAD achieves better performance than G. 729 Annex B at any noise level with a high artificial-to-intelligence ratio.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116677903","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783318
P. Tran, N. Boukhatem
Once a mobile node is equipped with multiple interfaces, it is possible to select dynamically the best interface according to different attributes such as the interface characteristics, user preferences, application preferences, ... In this paper, we propose the shortest distance to positive ideal attribute (SiPiA) algorithm to help terminal to dynamically select the best interface while avoiding the raking abnormality problem, one of the main limits of the TOPSIS method. Simulation results are presented to validate the SiPiA approach.
{"title":"SiPiA: The Shortest Distance to Positive Ideal Attribute for Interface Selection","authors":"P. Tran, N. Boukhatem","doi":"10.1109/ATNAC.2008.4783318","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783318","url":null,"abstract":"Once a mobile node is equipped with multiple interfaces, it is possible to select dynamically the best interface according to different attributes such as the interface characteristics, user preferences, application preferences, ... In this paper, we propose the shortest distance to positive ideal attribute (SiPiA) algorithm to help terminal to dynamically select the best interface while avoiding the raking abnormality problem, one of the main limits of the TOPSIS method. Simulation results are presented to validate the SiPiA approach.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125324660","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783299
Sung-Ju Lee, Jae-Seon Yoon, Hyoung-Kyu Song
In this paper, we propose a cooperative communation scheme using multi-symbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), in which one cyclic prefix (CP) is used for multiple OFDM symbols. We use the FFT size-reduced MSE-OFDM system which can be used to reduce the peak-to-average power ratio (PAPR) and improve the robustness to carrier frequency offset. The cooperative communication uses not only direct path from source to destination but also indirect path via relay station. Each different relays require more precise frequency synchronization and lower PAPR, so we adopt the MSE-OFDM to increase the system performance. The performance analysis of cooperative MSE-OFDM in multipath fading channels has been done and the effect of carrier frequency offset and PAPR have been studied.
{"title":"Carrier Frequency Offset Mitigation Using MSE-OFDM in Cooperative Communications","authors":"Sung-Ju Lee, Jae-Seon Yoon, Hyoung-Kyu Song","doi":"10.1109/ATNAC.2008.4783299","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783299","url":null,"abstract":"In this paper, we propose a cooperative communation scheme using multi-symbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), in which one cyclic prefix (CP) is used for multiple OFDM symbols. We use the FFT size-reduced MSE-OFDM system which can be used to reduce the peak-to-average power ratio (PAPR) and improve the robustness to carrier frequency offset. The cooperative communication uses not only direct path from source to destination but also indirect path via relay station. Each different relays require more precise frequency synchronization and lower PAPR, so we adopt the MSE-OFDM to increase the system performance. The performance analysis of cooperative MSE-OFDM in multipath fading channels has been done and the effect of carrier frequency offset and PAPR have been studied.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123319976","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783349
F. de Castro Louback Rocha, L. B. Ruiz
Some proposals are found on the literature for decentralizing SIP-based Voice over IP (VoIP) systems, replacing the client-server architecture for a P2P overlay network but none of the proposed solutions deploying a P2P network had studied the impacting of decentralization on call setup delay. We proposed a system using Kademlia instead of a centralized user location approach. Kademlia offers concurrent searches and this improves the latency in user location and thus provide a faster call establishment when the network experiences different delays, as showed in this study. In this paper it is also described how the system using Kademlia works as well as the tests performed in order to measure the impact on call establishment time when decentralizing a user location service on an IP telephony system.
{"title":"A Study of the Effect of Using Kademlia as an Alternative to Centralized User Location Servers in SIP-based IP Telephony Systems","authors":"F. de Castro Louback Rocha, L. B. Ruiz","doi":"10.1109/ATNAC.2008.4783349","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783349","url":null,"abstract":"Some proposals are found on the literature for decentralizing SIP-based Voice over IP (VoIP) systems, replacing the client-server architecture for a P2P overlay network but none of the proposed solutions deploying a P2P network had studied the impacting of decentralization on call setup delay. We proposed a system using Kademlia instead of a centralized user location approach. Kademlia offers concurrent searches and this improves the latency in user location and thus provide a faster call establishment when the network experiences different delays, as showed in this study. In this paper it is also described how the system using Kademlia works as well as the tests performed in order to measure the impact on call establishment time when decentralizing a user location service on an IP telephony system.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132082311","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783326
N. Linh-Trung, D. Van Phong, Z. M. Hussain, H. T. Huynh, V.L. Morgan, J. Gore
Compressed sensing, viewed as a type of random undersampling, considers the acquisition and reconstruction of sparse or compressible signals at a rate significantly lower than that of Nyquist. Exact reconstruction from incompletely acquired random measurements is, under certain constraints, achievable with high probability. However, randomness may not always be desirable in certain applications. Taking a nonrandom approach using deterministic chaos and following closely a recently proposed novel efficient structure of chaos filters, we propose a chaos filter structure by exploring the use of chaotic deterministic processes in designing the filter taps. By numerical performance, we show that, chaos filters generated by the logistic map, while being possible to exactly reconstruct original time-sparse signals from their incompletely acquired measurements, outperforms random filters.
{"title":"Compressed Sensing using Chaos Filters","authors":"N. Linh-Trung, D. Van Phong, Z. M. Hussain, H. T. Huynh, V.L. Morgan, J. Gore","doi":"10.1109/ATNAC.2008.4783326","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783326","url":null,"abstract":"Compressed sensing, viewed as a type of random undersampling, considers the acquisition and reconstruction of sparse or compressible signals at a rate significantly lower than that of Nyquist. Exact reconstruction from incompletely acquired random measurements is, under certain constraints, achievable with high probability. However, randomness may not always be desirable in certain applications. Taking a nonrandom approach using deterministic chaos and following closely a recently proposed novel efficient structure of chaos filters, we propose a chaos filter structure by exploring the use of chaotic deterministic processes in designing the filter taps. By numerical performance, we show that, chaos filters generated by the logistic map, while being possible to exactly reconstruct original time-sparse signals from their incompletely acquired measurements, outperforms random filters.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132762204","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783295
P. Fitzpatrick, M. Ivanovich
Beyond 3G wireless systems will support real time and elastic traffic over a common packet-switched radio channel using QoS mechanisms. This paper studies the key question of how to estimate the throughput performance of "best effort" elastic traffic when it is subject to available capacity variations due to changes in (i) the amount of higher priority traffic and (ii) the radio channel. We extend previous work in this area to show that for the QoS mechanisms studied, an equivalent PS model provides a good closed-form approximation to call-average throughput, with desirable properties of independence from radio channel variations and best effort call volume distribution. Our findings therefore provide a basis for practically estimating throughput performance of best effort traffic with arbitrary call volume distribution, in radio systems with multiple QoS levels and complex rate variability.
{"title":"On Approximating Throughput in Wireless Systems with Complex Rate Variability and QoS","authors":"P. Fitzpatrick, M. Ivanovich","doi":"10.1109/ATNAC.2008.4783295","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783295","url":null,"abstract":"Beyond 3G wireless systems will support real time and elastic traffic over a common packet-switched radio channel using QoS mechanisms. This paper studies the key question of how to estimate the throughput performance of \"best effort\" elastic traffic when it is subject to available capacity variations due to changes in (i) the amount of higher priority traffic and (ii) the radio channel. We extend previous work in this area to show that for the QoS mechanisms studied, an equivalent PS model provides a good closed-form approximation to call-average throughput, with desirable properties of independence from radio channel variations and best effort call volume distribution. Our findings therefore provide a basis for practically estimating throughput performance of best effort traffic with arbitrary call volume distribution, in radio systems with multiple QoS levels and complex rate variability.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134286348","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 : 2008-12-01DOI: 10.1109/ATNAC.2008.4783305
Ming-Shen Jian, S. Hsu
This paper develops an evolutionary multiple channel management based on mobility in multiple hop wireless network. The n-hops limitation theories are proposed first. Based upon these theories, the enhanced multiple channel management is proposed which consists of channel assignment method and topology prediction method. The channel assignment method is based on the enhanced genetic algorithm. Mobile devices are assigned different data channels individually and can be directly established without any RES message cost. All mobile nodes can communicate based upon the assigned potential channels. Also, due to the change of topology of all mobile devices, a topology prediction method is proposed to predict the velocities and directions of all mobile nodes. Simulation shows that the proposed management can make the success communication about 9.7~129.3% more than the competing algorithm.
{"title":"Evolutionary Multi-Channel Management based on Mobility in Multi-Hops Heterogeneous Wireless Networks","authors":"Ming-Shen Jian, S. Hsu","doi":"10.1109/ATNAC.2008.4783305","DOIUrl":"https://doi.org/10.1109/ATNAC.2008.4783305","url":null,"abstract":"This paper develops an evolutionary multiple channel management based on mobility in multiple hop wireless network. The n-hops limitation theories are proposed first. Based upon these theories, the enhanced multiple channel management is proposed which consists of channel assignment method and topology prediction method. The channel assignment method is based on the enhanced genetic algorithm. Mobile devices are assigned different data channels individually and can be directly established without any RES message cost. All mobile nodes can communicate based upon the assigned potential channels. Also, due to the change of topology of all mobile devices, a topology prediction method is proposed to predict the velocities and directions of all mobile nodes. Simulation shows that the proposed management can make the success communication about 9.7~129.3% more than the competing algorithm.","PeriodicalId":143803,"journal":{"name":"2008 Australasian Telecommunication Networks and Applications Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122960132","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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