Pub Date : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594857
Mirela Marta, M. Cardei
A critical issue for data gathering in wireless sensor networks is the formation of energy holes near the sinks. Sensors near the sinks have to participate in relaying data on behalf of other sensors and thus will deplete their energy very quickly, resulting in network partitioning and limitation of the network lifetime. The solution that we propose in this paper is to use mobile sinks that change their location when the nearby sensorspsila energy becomes low. In this way the sensors located near sinks change over time. In deciding a new location, a sink searches for zones with richer sensor energy. First, we study the improvement in network lifetime when sinks move on a predetermined path, along the perimeter of a hexagonal tiling. Two cases are considered for data gathering when sinks stop in the hexagonpsilas corners and when the sinks stop on multiple locations on the hexagon perimeter. This study shows an improvement of up to 4.86 times in network lifetime. Second, we design a distributed and localized algorithm used by the sinks to decide their next movement location such that the virtual backbone formed by the sinks remains interconnected at all times. Simulation results are presented to verify our approaches.
{"title":"Using sink mobility to increase wireless sensor networks lifetime","authors":"Mirela Marta, M. Cardei","doi":"10.1109/WOWMOM.2008.4594857","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594857","url":null,"abstract":"A critical issue for data gathering in wireless sensor networks is the formation of energy holes near the sinks. Sensors near the sinks have to participate in relaying data on behalf of other sensors and thus will deplete their energy very quickly, resulting in network partitioning and limitation of the network lifetime. The solution that we propose in this paper is to use mobile sinks that change their location when the nearby sensorspsila energy becomes low. In this way the sensors located near sinks change over time. In deciding a new location, a sink searches for zones with richer sensor energy. First, we study the improvement in network lifetime when sinks move on a predetermined path, along the perimeter of a hexagonal tiling. Two cases are considered for data gathering when sinks stop in the hexagonpsilas corners and when the sinks stop on multiple locations on the hexagon perimeter. This study shows an improvement of up to 4.86 times in network lifetime. Second, we design a distributed and localized algorithm used by the sinks to decide their next movement location such that the virtual backbone formed by the sinks remains interconnected at all times. Simulation results are presented to verify our approaches.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123546325","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594916
H. Cycon, T. Schmidt, G. Hege, Matthias Wählisch, D. Marpe, M. Palkow
A rapidly growing number of carriers offer wireless video services to their customers, taking advantage of high quality video codecs implemented in dedicated hardware of selected mobile devices. In this paper we introduce a video conferencing software, which seamlessly integrates mobile with stationary users in a provider and device independent fashion. Innovations of this work are twofold. At first we report on a mobile realization of an H.264 video codec and its performance on a standard consumer Smartphone. Operating within the tight bounds of real-time compliance on mobiles, this software is an adapted version of a highly optimized H.264 codec. This DAVC codec, which we introduce along the line, significantly out-performs compatible H.264 realizations and allows for a scalable adaptation of its frame rate. In the second part we present a barrier-resistant peer-to-peer group communication scheme, which scales well for medium-size conferences and accounts for the heterogeneous nature of mobile and stationary participants. An outlook on mobility related group communication issues and future optimizations based on structured communication layers concludes the work.
{"title":"Peer-to-peer videoconferencing with H.264 software codec for mobiles","authors":"H. Cycon, T. Schmidt, G. Hege, Matthias Wählisch, D. Marpe, M. Palkow","doi":"10.1109/WOWMOM.2008.4594916","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594916","url":null,"abstract":"A rapidly growing number of carriers offer wireless video services to their customers, taking advantage of high quality video codecs implemented in dedicated hardware of selected mobile devices. In this paper we introduce a video conferencing software, which seamlessly integrates mobile with stationary users in a provider and device independent fashion. Innovations of this work are twofold. At first we report on a mobile realization of an H.264 video codec and its performance on a standard consumer Smartphone. Operating within the tight bounds of real-time compliance on mobiles, this software is an adapted version of a highly optimized H.264 codec. This DAVC codec, which we introduce along the line, significantly out-performs compatible H.264 realizations and allows for a scalable adaptation of its frame rate. In the second part we present a barrier-resistant peer-to-peer group communication scheme, which scales well for medium-size conferences and accounts for the heterogeneous nature of mobile and stationary participants. An outlook on mobility related group communication issues and future optimizations based on structured communication layers concludes the work.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114951127","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594892
M. Pitkänen, A. Keränen, J. Ott
Delay-tolerant networking is used for communication in challenged environments such as MANETs, in which links are unstable and end-to-end paths between communicating nodes may not exist. Messages may be significantly larger than packets in IP networks. Large messages lead to longer transfer times rendering it more likely that a link breaks in the middle of a message transfer. This motivates investigating how to support partial message transfers through fragmentation. In this paper, we formulate fragmentation independent of routing algorithms, introduce several fragmentation strategies, and evaluate these by simulations to derive recommendations for using fragmentation in DTNs.
{"title":"Message fragmentation in opportunistic DTNs","authors":"M. Pitkänen, A. Keränen, J. Ott","doi":"10.1109/WOWMOM.2008.4594892","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594892","url":null,"abstract":"Delay-tolerant networking is used for communication in challenged environments such as MANETs, in which links are unstable and end-to-end paths between communicating nodes may not exist. Messages may be significantly larger than packets in IP networks. Large messages lead to longer transfer times rendering it more likely that a link breaks in the middle of a message transfer. This motivates investigating how to support partial message transfers through fragmentation. In this paper, we formulate fragmentation independent of routing algorithms, introduce several fragmentation strategies, and evaluate these by simulations to derive recommendations for using fragmentation in DTNs.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125273820","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594833
Huan Li, Haitao Lin, Hee Lee, P. Das
The major wireless operators are actively migrating their networks from circuit switched networks to all packet (IP) based next generation networks. One of the key issues impeding the migration is the associated cost. Though managing the CAPEX (CAPital EXpenditures) and OPEX (OPerational EXpenditure) has been the focus of the operators, minimizing the cost from the perspective of system design has received relatively less attention. In this paper, we investigate a particular trunk allocation problem in a circuit/packet hybrid switch to show how system and algorithm design can significantly reduce the migration cost, so that the operators achieve cost effective migration. In such a problem, allocating different trunk types to the two legs of a call/session results in utilization of a special hardware - an interworking unit to bridge the two types of trunks (TDM and IP) so that the call can be completed. The interworking unit is costly to the operators since it is a pure migration cost with no value after the migration. The key to minimize such cost lies in algorithm design to minimize the traffic requirement of the interworking unit, which is a challenging task due to the complexity of the problem. We develop an analytic model to characterize the traffic over the interworking unit in a hybrid switch with both packet and circuit trunk resources. The system is decoupled into two subsystems, each of which is modeled as a two-dimensional Markov chain. Exact solution of the model is provided through a recursion, and an iterative algorithm is developed to eliminate the difficulty in finding the solution for a large scale system. The accuracy of the iterative algorithm is verified by the simulation results from a OPNET simulation model. The numerical results show the algorithm is very accurate. It can be used to optimize the system resource provisioning and traffic distribution for minimizing the bridged traffic in a hybrid switch. Our results demonstrate it can provide significant cost and performance benefit during migration from TDM networks to next generation packet networks.
{"title":"Optimizing the cost of migration from wireless tdm networks to next generation packet networks","authors":"Huan Li, Haitao Lin, Hee Lee, P. Das","doi":"10.1109/WOWMOM.2008.4594833","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594833","url":null,"abstract":"The major wireless operators are actively migrating their networks from circuit switched networks to all packet (IP) based next generation networks. One of the key issues impeding the migration is the associated cost. Though managing the CAPEX (CAPital EXpenditures) and OPEX (OPerational EXpenditure) has been the focus of the operators, minimizing the cost from the perspective of system design has received relatively less attention. In this paper, we investigate a particular trunk allocation problem in a circuit/packet hybrid switch to show how system and algorithm design can significantly reduce the migration cost, so that the operators achieve cost effective migration. In such a problem, allocating different trunk types to the two legs of a call/session results in utilization of a special hardware - an interworking unit to bridge the two types of trunks (TDM and IP) so that the call can be completed. The interworking unit is costly to the operators since it is a pure migration cost with no value after the migration. The key to minimize such cost lies in algorithm design to minimize the traffic requirement of the interworking unit, which is a challenging task due to the complexity of the problem. We develop an analytic model to characterize the traffic over the interworking unit in a hybrid switch with both packet and circuit trunk resources. The system is decoupled into two subsystems, each of which is modeled as a two-dimensional Markov chain. Exact solution of the model is provided through a recursion, and an iterative algorithm is developed to eliminate the difficulty in finding the solution for a large scale system. The accuracy of the iterative algorithm is verified by the simulation results from a OPNET simulation model. The numerical results show the algorithm is very accurate. It can be used to optimize the system resource provisioning and traffic distribution for minimizing the bridged traffic in a hybrid switch. Our results demonstrate it can provide significant cost and performance benefit during migration from TDM networks to next generation packet networks.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128718473","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594899
J. Etherton, R. Clark, Matt Sanders
Location-based services are playing an increasingly important role in the rapidly evolving world of mobile applications. Despite this importance, there are numerous challenges to providing a widely implemented and usable service that spans multiple places, devices, and location technologies. This paper describes WhereAmI, a unique location services testbed that addresses these challenges and is enabling significant research and development of location-based applications and services.
{"title":"WhereAmI: A realworld testbed for location services","authors":"J. Etherton, R. Clark, Matt Sanders","doi":"10.1109/WOWMOM.2008.4594899","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594899","url":null,"abstract":"Location-based services are playing an increasingly important role in the rapidly evolving world of mobile applications. Despite this importance, there are numerous challenges to providing a widely implemented and usable service that spans multiple places, devices, and location technologies. This paper describes WhereAmI, a unique location services testbed that addresses these challenges and is enabling significant research and development of location-based applications and services.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128775571","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594909
A. Lazaris, P. Koutsakis
In this work, we first introduce a new traffic model for medium quality MPEG-4 videoconference traffic and then proceed to use it in the implementation of a new call admission control scheme. Our scheme makes decisions on the acceptance/rejection of a new video call not only based on the predicted capacity that users will consume, but also on the possible revenue gained for the provider when degrading current users in order to accommodate new ones. Via an extensive simulation study our scheme is shown to provide excellent quality of service (QoS) to wireless videoconference users.
{"title":"Revenue-based Call Admission Control for MPEG-4 wireless videoconference traffic","authors":"A. Lazaris, P. Koutsakis","doi":"10.1109/WOWMOM.2008.4594909","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594909","url":null,"abstract":"In this work, we first introduce a new traffic model for medium quality MPEG-4 videoconference traffic and then proceed to use it in the implementation of a new call admission control scheme. Our scheme makes decisions on the acceptance/rejection of a new video call not only based on the predicted capacity that users will consume, but also on the possible revenue gained for the provider when degrading current users in order to accommodate new ones. Via an extensive simulation study our scheme is shown to provide excellent quality of service (QoS) to wireless videoconference users.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"228 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127891435","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594873
Dawei Liu, Moon-Chuen Lee
Due to the advent of many location based applications, mobile localization in outdoor environments has recently attracted much attention. Many existing localization solutions rely primarily on a hybrid wireless network/dead reckoning (DR) method, as the regular wireless network can hardly estimate a location with satisfactory accuracy in bad channel conditions. However, the DR scheme can involve considerable hardware investments, moreover, it suffers from serious error accumulations in motion measurements of a mobile object. To remedy drawbacks of the hybrid method, we present a novel mobile localization scheme based on the concept of pseudo beacon. The proposed scheme can perform network localization in those areas where traditional wireless networks may not work, and thus, avoids large investments the special hardware cost and error accumulations of DR. Extensive real world GPS experimental results demonstrate the significant superiority of the proposed scheme.
{"title":"Mobile localization in outdoor environments","authors":"Dawei Liu, Moon-Chuen Lee","doi":"10.1109/WOWMOM.2008.4594873","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594873","url":null,"abstract":"Due to the advent of many location based applications, mobile localization in outdoor environments has recently attracted much attention. Many existing localization solutions rely primarily on a hybrid wireless network/dead reckoning (DR) method, as the regular wireless network can hardly estimate a location with satisfactory accuracy in bad channel conditions. However, the DR scheme can involve considerable hardware investments, moreover, it suffers from serious error accumulations in motion measurements of a mobile object. To remedy drawbacks of the hybrid method, we present a novel mobile localization scheme based on the concept of pseudo beacon. The proposed scheme can perform network localization in those areas where traditional wireless networks may not work, and thus, avoids large investments the special hardware cost and error accumulations of DR. Extensive real world GPS experimental results demonstrate the significant superiority of the proposed scheme.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124484743","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594890
C. Boldrini, M. Conti, A. Passarella
Opportunistic networks are challenging mobile ad hoc networks characterised by frequent disconnections and partitioning. In this paper we focus on data dissemination services, i.e. cases in which data should be disseminated in the network without a priori knowledge about the set of intended destinations. We propose a general autonomic data dissemination framework that exploits information about the userspsila context and social behaviour, to decide how to replicate and replace data on nodespsila buffers. Furthermore, our data dissemination scheme explicitly takes into account resource constraints, by jointly considering the expected utility of data replication and the associated costs. The results we present show that our solution is able to improve data availability, provide fairness among nodes, and reduce the network load, with respect to reference proposals available in the literature.
{"title":"Context and resource awareness in opportunistic network data dissemination","authors":"C. Boldrini, M. Conti, A. Passarella","doi":"10.1109/WOWMOM.2008.4594890","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594890","url":null,"abstract":"Opportunistic networks are challenging mobile ad hoc networks characterised by frequent disconnections and partitioning. In this paper we focus on data dissemination services, i.e. cases in which data should be disseminated in the network without a priori knowledge about the set of intended destinations. We propose a general autonomic data dissemination framework that exploits information about the userspsila context and social behaviour, to decide how to replicate and replace data on nodespsila buffers. Furthermore, our data dissemination scheme explicitly takes into account resource constraints, by jointly considering the expected utility of data replication and the associated costs. The results we present show that our solution is able to improve data availability, provide fairness among nodes, and reduce the network load, with respect to reference proposals available in the literature.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124549433","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594903
O. Issa, Jean-Charles Grégoire, Y. Belala, J. Wong
A variety of wireless access technologies provides todaypsilas users with pervasive access to critical content and applications. Guaranteeing a satisfactory quality of service requires reliable and ubiquitous delivery schemes that optimally use the available access technologies. This paper presents a novel architecture to support adaptive real-time data and multimedia applications over different wireless technologies. It addresses several issues associated with the satisfactory operation of applications running over heterogeneous networks. The system is validated using a real-life healthcare application capable of transmitting voice, video and medical data simultaneously. Experimental results are reported that demonstrate the viability of the approach.
{"title":"An embedded platform for reliable applications over heterogeneous wireless networks","authors":"O. Issa, Jean-Charles Grégoire, Y. Belala, J. Wong","doi":"10.1109/WOWMOM.2008.4594903","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594903","url":null,"abstract":"A variety of wireless access technologies provides todaypsilas users with pervasive access to critical content and applications. Guaranteeing a satisfactory quality of service requires reliable and ubiquitous delivery schemes that optimally use the available access technologies. This paper presents a novel architecture to support adaptive real-time data and multimedia applications over different wireless technologies. It addresses several issues associated with the satisfactory operation of applications running over heterogeneous networks. The system is validated using a real-life healthcare application capable of transmitting voice, video and medical data simultaneously. Experimental results are reported that demonstrate the viability of the approach.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131028937","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 : 2008-06-23DOI: 10.1109/WOWMOM.2008.4594836
S. Makharia, D. Raychaudhuri, Mingquan Wu, Hang Liu, Dekai Li
We report the design, implementation and evaluation of Merged Hybrid ARQ with staggered FEC (MHARQ) system for video multicast over wireless LANs. MHARQ combines the advantages of receiver-driven staggered FEC and hybrid ARQ schemes to compensate the large dynamic range of WLAN channels and to achieve high reliability, scalability and wireless bandwidth efficiency for video multicast. The FEC packets generated by a cross-packet FEC code are divided into multiple streams according to the pre-configured overhead and are transmitted in different multiple IP multicast groups. Certain FEC streams are delayed from the original video stream. The receivers dynamically join/leave the FEC multicast groups based on the channel conditions. For efficient utilization of WLAN bandwidth, FEC data for a multicast group would not be transmitted by the APs in wireless networks if no receiver joins this group. The time shift between the video stream and the FEC streams introduces temporal diversity and compensates for the client join delay and handoff interruption. In addition, when delayed FEC packets are not enough to recover the lost packets, the receivers can send a hybrid ARQ request to the video server. We design a channel estimation algorithm for a receiver to dynamically determine the delayed FEC multicast groups to join and/or send ARQ NACK to request for retransmission. Using the ORBIT radio grid testbed, we have investigated the performance of the proposed MHARQ system with various numbers of users per AP and different number of APs per video server. It is demonstrated via real system implementation on ORBIT that MHARQ improves wireless bandwidth efficiency and scalability for reliable video multicast, compared with existing reliable multicast schemes.
{"title":"Experimental study on wireless multicast scalability using Merged Hybrid ARQ with staggered adaptive FEC","authors":"S. Makharia, D. Raychaudhuri, Mingquan Wu, Hang Liu, Dekai Li","doi":"10.1109/WOWMOM.2008.4594836","DOIUrl":"https://doi.org/10.1109/WOWMOM.2008.4594836","url":null,"abstract":"We report the design, implementation and evaluation of Merged Hybrid ARQ with staggered FEC (MHARQ) system for video multicast over wireless LANs. MHARQ combines the advantages of receiver-driven staggered FEC and hybrid ARQ schemes to compensate the large dynamic range of WLAN channels and to achieve high reliability, scalability and wireless bandwidth efficiency for video multicast. The FEC packets generated by a cross-packet FEC code are divided into multiple streams according to the pre-configured overhead and are transmitted in different multiple IP multicast groups. Certain FEC streams are delayed from the original video stream. The receivers dynamically join/leave the FEC multicast groups based on the channel conditions. For efficient utilization of WLAN bandwidth, FEC data for a multicast group would not be transmitted by the APs in wireless networks if no receiver joins this group. The time shift between the video stream and the FEC streams introduces temporal diversity and compensates for the client join delay and handoff interruption. In addition, when delayed FEC packets are not enough to recover the lost packets, the receivers can send a hybrid ARQ request to the video server. We design a channel estimation algorithm for a receiver to dynamically determine the delayed FEC multicast groups to join and/or send ARQ NACK to request for retransmission. Using the ORBIT radio grid testbed, we have investigated the performance of the proposed MHARQ system with various numbers of users per AP and different number of APs per video server. It is demonstrated via real system implementation on ORBIT that MHARQ improves wireless bandwidth efficiency and scalability for reliable video multicast, compared with existing reliable multicast schemes.","PeriodicalId":346269,"journal":{"name":"2008 International Symposium on a World of Wireless, Mobile and Multimedia Networks","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130487658","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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