城市车载网的多跳路由问题研究
摘要
进入21世纪以来,汽车逐渐成为人们日常生活的主要交通工具。汽车数量的增长也产生了一系列社会问题,甚至带来负面影响。车载自组网作为智能交通系统的重要组成部分,能够有效改善交通安全状况,提高道路通行效率,降低能源消耗,最大限度地提高车辆的安全和效率。其中,城市是车载自组网最重要的应用场景,本文针对城市车载网的多跳路由技术进行了一些研究。
车载自组网是一类特殊的移动自组网,二者之间存在较大差异,故不能把移动自组网的路由协议直接应用到车载自组网。因此,本文所采取的研究方法是:首先,比较分析了移动自组网和车载自组网的移动模型,提出了一种新的基于地图的城市移动模型CTM,该模型采用了真实的道路形状,并模拟了车流量不均衡的特征。然后本文将CTM和移动自组网的常用移动模型进行了仿真,其中包括网络连通率、节点密度以及链路持续时间等。结果定量地说明了车载自组网与移动自组网的差异:一方面车载自组网拓扑变化频繁,端到端路由路径生存时间短;另一方面网络存在分割,部分节点某些时刻不存在到目的节点的路径。然后,本文针对这些特征设计了一种新的城市车载网多跳路由协议CDVR。该协议将城市多跳路由划分成路段路由和路口路由两个部分,车辆在路段上行驶时采用基于地理位置的贪婪算法,而当车辆行驶到路口时根据道路的连通度进行转发。最后,本文利用NS2平台对AODV,GPSR,Epidemic和CDVR协议进行了比较,仿真结果说明:在城市车载网中,CDVR的多跳路由性能优于其它三种协议。在网络快速变化和存在分割的情况下,CDVR能够达到较高的发送成功率和较低的传输延迟,并且CDVR的控制负载很轻,协议可扩性强,能够适用于大规模的车载自组网应用。
Since the beginning of the 21st century,car has been a major transportation in our daily life. However the growing number of cars also produced a series of social problems, even bringing negative effects. Since the vehicle ad hoc network (VANET) is an important part of the intelligent transportation system, it can greatly improve the road safety and traffic efficiency, also reducing energy consumption. City is the most important scenario for VANET application, so this paper has done some research on multi-hop routing problem for urban vehicle ad hoc network.
VANET is a special kind of mobile ad hoc network (MANET), but we can't apply the routing protocol of MANET directly to the VANET because these two kinds of networks are quite different. Accordingly, our methodologies are as below: First, we analyses and comprises the mobility models of both MANET and VANET. In this paper, we present a new map-based urban mobility model called CTM. CTM adopts the real road shape according to the digital map and implements the uneven distribution of vehicles among roads. Then, a series of network metrics are proposed including the ratio of network connectivity, node density, link duration, etc, and we simulate the RWP, Manhattan and CTM model respectively based on these metrics. Results show two main differences between MANET and VANET: In the one hand, the topology of VANET changes frequently and the life of the end-to-end path is short. In another hand, VANET has segmentation, which sometimes results in the missing path from source to destination. Motivated by this, we design a new urban multi-hop routing protocol called CDVR to solve the above problem. CDVR divides the routing into two modes, road routing and intersection routing. When car is on the road, the protocol chooses greedy algorithm to forward the data based on the geographical position. When car is arriving at the intersection, the protocol forwards the data based on the connectivity of road. Finally, we use NS2 to simulate and analysis the protocol of AODV, GPSR, Epidemic and CDVR. Results show that in VANET the routing performance of CDVR is more superior to the other three protocols. CDVR can achieve high data delivery ratio and low transmission delay under the network of rapid changing and segmentation, and also CDVR is lightweight and scalable which promises large-scale applications of VANET.
车载自组网是一类特殊的移动自组网,二者之间存在较大差异,故不能把移动自组网的路由协议直接应用到车载自组网。因此,本文所采取的研究方法是:首先,比较分析了移动自组网和车载自组网的移动模型,提出了一种新的基于地图的城市移动模型CTM,该模型采用了真实的道路形状,并模拟了车流量不均衡的特征。然后本文将CTM和移动自组网的常用移动模型进行了仿真,其中包括网络连通率、节点密度以及链路持续时间等。结果定量地说明了车载自组网与移动自组网的差异:一方面车载自组网拓扑变化频繁,端到端路由路径生存时间短;另一方面网络存在分割,部分节点某些时刻不存在到目的节点的路径。然后,本文针对这些特征设计了一种新的城市车载网多跳路由协议CDVR。该协议将城市多跳路由划分成路段路由和路口路由两个部分,车辆在路段上行驶时采用基于地理位置的贪婪算法,而当车辆行驶到路口时根据道路的连通度进行转发。最后,本文利用NS2平台对AODV,GPSR,Epidemic和CDVR协议进行了比较,仿真结果说明:在城市车载网中,CDVR的多跳路由性能优于其它三种协议。在网络快速变化和存在分割的情况下,CDVR能够达到较高的发送成功率和较低的传输延迟,并且CDVR的控制负载很轻,协议可扩性强,能够适用于大规模的车载自组网应用。
Since the beginning of the 21st century,car has been a major transportation in our daily life. However the growing number of cars also produced a series of social problems, even bringing negative effects. Since the vehicle ad hoc network (VANET) is an important part of the intelligent transportation system, it can greatly improve the road safety and traffic efficiency, also reducing energy consumption. City is the most important scenario for VANET application, so this paper has done some research on multi-hop routing problem for urban vehicle ad hoc network.
VANET is a special kind of mobile ad hoc network (MANET), but we can't apply the routing protocol of MANET directly to the VANET because these two kinds of networks are quite different. Accordingly, our methodologies are as below: First, we analyses and comprises the mobility models of both MANET and VANET. In this paper, we present a new map-based urban mobility model called CTM. CTM adopts the real road shape according to the digital map and implements the uneven distribution of vehicles among roads. Then, a series of network metrics are proposed including the ratio of network connectivity, node density, link duration, etc, and we simulate the RWP, Manhattan and CTM model respectively based on these metrics. Results show two main differences between MANET and VANET: In the one hand, the topology of VANET changes frequently and the life of the end-to-end path is short. In another hand, VANET has segmentation, which sometimes results in the missing path from source to destination. Motivated by this, we design a new urban multi-hop routing protocol called CDVR to solve the above problem. CDVR divides the routing into two modes, road routing and intersection routing. When car is on the road, the protocol chooses greedy algorithm to forward the data based on the geographical position. When car is arriving at the intersection, the protocol forwards the data based on the connectivity of road. Finally, we use NS2 to simulate and analysis the protocol of AODV, GPSR, Epidemic and CDVR. Results show that in VANET the routing performance of CDVR is more superior to the other three protocols. CDVR can achieve high data delivery ratio and low transmission delay under the network of rapid changing and segmentation, and also CDVR is lightweight and scalable which promises large-scale applications of VANET.
引文
[1]杨兆升.智能运输系统概论[M].北京:人民交通出版社, 2003.
[2] Mobile Ad Hoc Networks[EB/OL]. http://www.ietf.org/html.charters/manet-charter.html, 1997
[3] Fall Kevin. A delay-tolerant network architecture for challenged internets[J]. ACM SIGCOMM Conference, 2003: 27-34
[4]于宏毅.无线移动自组织网[M].北京:人民邮电出版社, 2005
[5]郑少仁,王海涛,赵志峰. Ad Hoc网络技术[M],北京:人民邮电出版社, 2005
[6] Perkins C.E, Bhagwat P. Highly Dynamic Destination-Sequenced Distance-Vector Routing for Mobile Computers[J]. Proc of ACM SIGCOMM Computer Communication Review, 1994: 234-244
[7] Clausen T, Jacquet P. Optimized Link State Routing Protocol (OLSR)[S]. RFC3626
[8] Perkins C.E, Royer E.M, Das S.R. Ad Hoc on Demand Distance Vector (AODV) Routing[S]. IETF Internet Draft, 2000
[9] Johnson D.B, Maltz D.A, Broch J. DSR: the dynamic source routing protocol for multi-hop wireless ad hoc networks[J]. Ad Hoc Networking, 2001: 139–172
[10] Heinzelman W.R, Chandrakasan A, Balakrishnan H. Energy-efficient communication protocol for wireless microsensor networks[J]. IEEE Proceedings of the Hawaii International Conference on System Sciences, 2000: 1–10
[11] Pearlman M, Haas Z.J. Determining the Optimal Configuration for Zone routing protocol[J]. Proc of IEEE Journal on Selected Areas in Communications, 1999, 17(8): 1395-1414
[12] Ko, Vaidya Y.B, N.H. Location-Aided Routing in Mobile Ad hoc Networks[J]. Proc of the 4th Annual ACM/IEEE International Conference on Mobile Computing and Networking, 1998: 66-75
[13] Karp B, Kung H.T. Greedy Perimeter Stateless Routing for Wireless Networks[J]. Proc of the 6th Annual International Conference on Mobile Computing and Networking, 2000: 243-254
[14]常促宇,向勇,史美林.车载自组网的现状与发展[J].通信学报, 2007, 28(11): 116-126
[15]陈立家,江昊,吴静,等.车用自组织网络传输控制研究[J].软件学报, 2007, 18(6): 1477-1490
[16] Blum J.J, Eskandarian A, Hoffman L.J. Challenges of Inter Vehicle Ad Hoc Networks[J]. Proc of IEEE Trans on Intelligent Transportation System, 2004: 347-351
[17] Jun Luo, Hubaux J.P. A Survey of Inter-Vehicle Communication. Technical Report[R]. 2004.
[18] TSUGAWA S, TOKUDA K, KATO S. An overview on DEMO 2000 cooperative driving. Proc of the IEEE Intelligent Vehicle Symposium (IV'01), 2001: 327-332
[19] CarTalk2000[EB/OL]. http://www.cartalk2000.net. 2001
[20] FleetNet Program[EB/OL]. http://www.fleetnet.de. 2000
[21] NOW: Network-on-Wheels[EB/OL].http://www.network-on-wheels.de. 2004
[22] Standard Specification for Telecommunications and Information Exchange Between roadside and Vehicle Systems - 5 GHz Band Dedicated Short Range Communications (DSRC) Medium Access Control (MAC) and Physical Layer (PHY) Specifications[S]. 2003
[23] IEEE Std 802.11. Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specification[S]. 1999
[24]陈晓静,何荣希.车载Ad Hoc网络MAC协议研究[J].计算机工程与设计, 2008, 29(12): 3071-3074
[25]安建伟,周贤伟,黄欢,等.车载自组网MAC层的安全问题研究[J].计算机应用研究, 2009, 26(5):1891-1895
[26]刘江永,张洋洋,韩鹏.不同场景中VANET路由协议的仿真研究[J].计算机工程与应用, 2009, 45(18): 101-103
[27]李元振,廖建新,李彤红,等.一种基于竞争转发的城市场景车载Ad Hoc网络路由算法[J].电子学报, 2009, 37(12):2639-2645
[28]张国庆,慕德俊,洪亮,等.城市场景下VANET路由协议大规模仿真研究[J].计算机仿真, 2009, 26(8): 249-252
[29]周欢,徐守志,李成霞.一种用于高速公路上防车辆连环碰撞的V2V广播协议[J].计算机研究与发展, 2009, 46(12): 2062-2067
[30]江进,陈闳中,方钰.基于车辆自组网络的分布式自主导航系统[J].计算机工程. 2009, 35(2): 274-276
[31] USDOT Outlines the New VII Initiative at the 2004 TRB Annual Meeting[EB/OL]. http://www.its.dot.gov.
[32] NADEEM T, DASHTINEZHAD S, LIAO C. TrafficView: Traffic data dissemination using car-to-car communication[J]. ACM SIGMOBILE Mobile Computing and Communications Review, 2004, 8(3): 6-19
[33] UMTS-TDD[EB/OL]. http://www.umts-forum.org. 2006.
[34] Yang X, Liu J, Zhao F, et al. A vehicle-to-vehicle communication protocol for cooperative collision warning[J]. Proc. Int. Conf. MobiQuitous, 2004: 114–123
[35] Murthy S and Garcia-Luna-Aceves J.J, An Efficient Routing Protocol for Wireless Networks[J]. ACM Mobile Networks and Applications, 1996: 183–97
[36] Li J, Jannotti J, Douglas S.J, et al. A Scalable Location Service for Geographic Ad hoc Routing[J]. Proc of the 6th Annual International Conference on Mobile Computing and Networking, 2000: 120-130
[37] Park V.D, Corson M.S. A Highly Adaptive Distributed Routing Algorithm for Mobile Wireless Networks[J]. Proc. INFOCOM , 1997: 1405-1413
[38] Verdone R. Multi-hop R-Aloha for inter-vehicle communication at millimeter waves[J] . IEEE Trans on Vehicular Technology, 2007: 992–1005
[39] Lott M, Halmann R, Schulz E, et al. Medium access and radio resource management for ad hoc networks based on UTRA TDD[J]. ACM Mobihoc Poster, 2001: 76–86
[40] Bychkovsky V, Hull B, Miu A, et al. A measurement study of vehicular internet access using in situ Wi-Fi networks[J]. ACM Mobicom, 2006: 50-61
[41] Ott J, Kutscher D. Drive-thru Internet: IEEE 802.11 b for automobile users[J]. IEEE Infocom, 2004: 362-373
[42] Schumacher H, Priemer C, Slottke E.N. A simulation study of traffic efficiency improvement based on Car-to-X communication[J]. ACM VANET, 2009: 13-22
[43] Rybicki J, Scheuermann B, Koegel M, et al. PeerTIS: a peer-to-peer traffic information system. ACM VANET, 2009: 23-32
[44] Lochert C, Hartenstein H, Tian J, et al. A Routing Strategy for Vehicular Ad Hoc Networks in City Environments[J]. Proc of Intelligent Vehicles Symposium. 2003: 156-161
[45] Navas J.C, Imielinski T. Geocast Geographic Addressing and Routing[J]. Proc of the 3rd annual ACM/IEEE international conference on Mobile computing and networking. 1997: 66-76
[46] Jung H, Lee S, Kim J. End-to-End Routing for Urban Vehicular Ad hoc Networks. International Symposium on Communications and Information Technology, 2009: 1504-1505
[47] Broch J, Maltz D.A, Johnson D.B, et al. A performance comparison of multi-hop wireless ad hoc network routing protocols[J]. Proceedings of the Fourth Annual ACM/IEEE International Conference on Mobile Computing and Networking, 1998: 85-97
[48] Hong X, Gerla M, Pei G, et al. A group mobility model for ad hoc wireless networks[J]. ACM/IEEE MSWiM, 1999: 53-60
[49] Bai F, Sadagopan N, Helmy A. IMPORTANT: A framework to systematically analyze the impact of mobility on performance of routing protocols for adhoc networks[J]. INFOCOM, 2003: 825-835
[50] Lochert C, Mauve M, Holger F. Geographic Routing in City Scenarios[J]. Proc of ACM SIGMOBILE Mobile Computing and Communications, 2005, 9(1): 69-72
[51] Seet B.C, Liu G, Lee B.S, et al. A Mobile Ad Hoc Routing Strategy for Metropolis Vehicular Communications[J]. Proc of International Conference on Information Networking, 2004: 134–143
[52] Vahdat A, Becker D. Epidemic routing for partially connected ad hoc networks[R]. Duke Univ: 2000
[53] Wisitpongphan N, Bai F, Mudalige P, et al. Routing in Sparse Vehicular Ad Hoc Wireless Networks[J]. IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, 2007, 25(8): 1538-1556
[54]徐雷鸣,庞博,赵耀. NS与网络模拟[M].北京:民邮电出版社, 2003
[55] Karp B. Challenges in Geographic Routing: Sparse Networks, Obstacles, and Traffic Provisioning[R]. Talk at DIMACS Workshop on Pervasive Networking: 2001
[2] Mobile Ad Hoc Networks[EB/OL]. http://www.ietf.org/html.charters/manet-charter.html, 1997
[3] Fall Kevin. A delay-tolerant network architecture for challenged internets[J]. ACM SIGCOMM Conference, 2003: 27-34
[4]于宏毅.无线移动自组织网[M].北京:人民邮电出版社, 2005
[5]郑少仁,王海涛,赵志峰. Ad Hoc网络技术[M],北京:人民邮电出版社, 2005
[6] Perkins C.E, Bhagwat P. Highly Dynamic Destination-Sequenced Distance-Vector Routing for Mobile Computers[J]. Proc of ACM SIGCOMM Computer Communication Review, 1994: 234-244
[7] Clausen T, Jacquet P. Optimized Link State Routing Protocol (OLSR)[S]. RFC3626
[8] Perkins C.E, Royer E.M, Das S.R. Ad Hoc on Demand Distance Vector (AODV) Routing[S]. IETF Internet Draft, 2000
[9] Johnson D.B, Maltz D.A, Broch J. DSR: the dynamic source routing protocol for multi-hop wireless ad hoc networks[J]. Ad Hoc Networking, 2001: 139–172
[10] Heinzelman W.R, Chandrakasan A, Balakrishnan H. Energy-efficient communication protocol for wireless microsensor networks[J]. IEEE Proceedings of the Hawaii International Conference on System Sciences, 2000: 1–10
[11] Pearlman M, Haas Z.J. Determining the Optimal Configuration for Zone routing protocol[J]. Proc of IEEE Journal on Selected Areas in Communications, 1999, 17(8): 1395-1414
[12] Ko, Vaidya Y.B, N.H. Location-Aided Routing in Mobile Ad hoc Networks[J]. Proc of the 4th Annual ACM/IEEE International Conference on Mobile Computing and Networking, 1998: 66-75
[13] Karp B, Kung H.T. Greedy Perimeter Stateless Routing for Wireless Networks[J]. Proc of the 6th Annual International Conference on Mobile Computing and Networking, 2000: 243-254
[14]常促宇,向勇,史美林.车载自组网的现状与发展[J].通信学报, 2007, 28(11): 116-126
[15]陈立家,江昊,吴静,等.车用自组织网络传输控制研究[J].软件学报, 2007, 18(6): 1477-1490
[16] Blum J.J, Eskandarian A, Hoffman L.J. Challenges of Inter Vehicle Ad Hoc Networks[J]. Proc of IEEE Trans on Intelligent Transportation System, 2004: 347-351
[17] Jun Luo, Hubaux J.P. A Survey of Inter-Vehicle Communication. Technical Report[R]. 2004.
[18] TSUGAWA S, TOKUDA K, KATO S. An overview on DEMO 2000 cooperative driving. Proc of the IEEE Intelligent Vehicle Symposium (IV'01), 2001: 327-332
[19] CarTalk2000[EB/OL]. http://www.cartalk2000.net. 2001
[20] FleetNet Program[EB/OL]. http://www.fleetnet.de. 2000
[21] NOW: Network-on-Wheels[EB/OL].http://www.network-on-wheels.de. 2004
[22] Standard Specification for Telecommunications and Information Exchange Between roadside and Vehicle Systems - 5 GHz Band Dedicated Short Range Communications (DSRC) Medium Access Control (MAC) and Physical Layer (PHY) Specifications[S]. 2003
[23] IEEE Std 802.11. Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specification[S]. 1999
[24]陈晓静,何荣希.车载Ad Hoc网络MAC协议研究[J].计算机工程与设计, 2008, 29(12): 3071-3074
[25]安建伟,周贤伟,黄欢,等.车载自组网MAC层的安全问题研究[J].计算机应用研究, 2009, 26(5):1891-1895
[26]刘江永,张洋洋,韩鹏.不同场景中VANET路由协议的仿真研究[J].计算机工程与应用, 2009, 45(18): 101-103
[27]李元振,廖建新,李彤红,等.一种基于竞争转发的城市场景车载Ad Hoc网络路由算法[J].电子学报, 2009, 37(12):2639-2645
[28]张国庆,慕德俊,洪亮,等.城市场景下VANET路由协议大规模仿真研究[J].计算机仿真, 2009, 26(8): 249-252
[29]周欢,徐守志,李成霞.一种用于高速公路上防车辆连环碰撞的V2V广播协议[J].计算机研究与发展, 2009, 46(12): 2062-2067
[30]江进,陈闳中,方钰.基于车辆自组网络的分布式自主导航系统[J].计算机工程. 2009, 35(2): 274-276
[31] USDOT Outlines the New VII Initiative at the 2004 TRB Annual Meeting[EB/OL]. http://www.its.dot.gov.
[32] NADEEM T, DASHTINEZHAD S, LIAO C. TrafficView: Traffic data dissemination using car-to-car communication[J]. ACM SIGMOBILE Mobile Computing and Communications Review, 2004, 8(3): 6-19
[33] UMTS-TDD[EB/OL]. http://www.umts-forum.org. 2006.
[34] Yang X, Liu J, Zhao F, et al. A vehicle-to-vehicle communication protocol for cooperative collision warning[J]. Proc. Int. Conf. MobiQuitous, 2004: 114–123
[35] Murthy S and Garcia-Luna-Aceves J.J, An Efficient Routing Protocol for Wireless Networks[J]. ACM Mobile Networks and Applications, 1996: 183–97
[36] Li J, Jannotti J, Douglas S.J, et al. A Scalable Location Service for Geographic Ad hoc Routing[J]. Proc of the 6th Annual International Conference on Mobile Computing and Networking, 2000: 120-130
[37] Park V.D, Corson M.S. A Highly Adaptive Distributed Routing Algorithm for Mobile Wireless Networks[J]. Proc. INFOCOM , 1997: 1405-1413
[38] Verdone R. Multi-hop R-Aloha for inter-vehicle communication at millimeter waves[J] . IEEE Trans on Vehicular Technology, 2007: 992–1005
[39] Lott M, Halmann R, Schulz E, et al. Medium access and radio resource management for ad hoc networks based on UTRA TDD[J]. ACM Mobihoc Poster, 2001: 76–86
[40] Bychkovsky V, Hull B, Miu A, et al. A measurement study of vehicular internet access using in situ Wi-Fi networks[J]. ACM Mobicom, 2006: 50-61
[41] Ott J, Kutscher D. Drive-thru Internet: IEEE 802.11 b for automobile users[J]. IEEE Infocom, 2004: 362-373
[42] Schumacher H, Priemer C, Slottke E.N. A simulation study of traffic efficiency improvement based on Car-to-X communication[J]. ACM VANET, 2009: 13-22
[43] Rybicki J, Scheuermann B, Koegel M, et al. PeerTIS: a peer-to-peer traffic information system. ACM VANET, 2009: 23-32
[44] Lochert C, Hartenstein H, Tian J, et al. A Routing Strategy for Vehicular Ad Hoc Networks in City Environments[J]. Proc of Intelligent Vehicles Symposium. 2003: 156-161
[45] Navas J.C, Imielinski T. Geocast Geographic Addressing and Routing[J]. Proc of the 3rd annual ACM/IEEE international conference on Mobile computing and networking. 1997: 66-76
[46] Jung H, Lee S, Kim J. End-to-End Routing for Urban Vehicular Ad hoc Networks. International Symposium on Communications and Information Technology, 2009: 1504-1505
[47] Broch J, Maltz D.A, Johnson D.B, et al. A performance comparison of multi-hop wireless ad hoc network routing protocols[J]. Proceedings of the Fourth Annual ACM/IEEE International Conference on Mobile Computing and Networking, 1998: 85-97
[48] Hong X, Gerla M, Pei G, et al. A group mobility model for ad hoc wireless networks[J]. ACM/IEEE MSWiM, 1999: 53-60
[49] Bai F, Sadagopan N, Helmy A. IMPORTANT: A framework to systematically analyze the impact of mobility on performance of routing protocols for adhoc networks[J]. INFOCOM, 2003: 825-835
[50] Lochert C, Mauve M, Holger F. Geographic Routing in City Scenarios[J]. Proc of ACM SIGMOBILE Mobile Computing and Communications, 2005, 9(1): 69-72
[51] Seet B.C, Liu G, Lee B.S, et al. A Mobile Ad Hoc Routing Strategy for Metropolis Vehicular Communications[J]. Proc of International Conference on Information Networking, 2004: 134–143
[52] Vahdat A, Becker D. Epidemic routing for partially connected ad hoc networks[R]. Duke Univ: 2000
[53] Wisitpongphan N, Bai F, Mudalige P, et al. Routing in Sparse Vehicular Ad Hoc Wireless Networks[J]. IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, 2007, 25(8): 1538-1556
[54]徐雷鸣,庞博,赵耀. NS与网络模拟[M].北京:民邮电出版社, 2003
[55] Karp B. Challenges in Geographic Routing: Sparse Networks, Obstacles, and Traffic Provisioning[R]. Talk at DIMACS Workshop on Pervasive Networking: 2001