外文翻譯--在zigbee網(wǎng)絡(luò)中的移動性支持評估

1、<p><b>　　中文6215字</b></p><p>　　畢業(yè)設(shè)計(論文)外文資料翻譯</p><p>　　原 文 題 目：An Evaluation Study of Mobility Support</p><p>　　in ZigBee Networks </p><p>　　原 文

2、 來 源： J Sign Process Syst (2010) 59:111–122</p><p>　　doi: 10.1007/s11265-008-0271-x </p><p>　　學(xué) 生 姓 名： </p><p>　　學(xué) 號： </p

3、><p>　　所在院(系)部： </p><p>　　專 業(yè) 名 稱： </p><p>　　J Sign Process Syst (2010) 59:111–122</p><p>　　DOI:10.1007/s11265-008-0271-x<

4、/p><p>　　An Evaluation Study of Mobility Support</p><p>　　in ZigBee Networks</p><p>　　Ling-Jyh Chen · Tony Sun · Nia-Chiang Liang</p><p>　　Received: 13 April 200

5、8 / Revised: 6 August 2008 / Accepted: 2 September 2008 / Published online: 16 October 2008</p><p>　　© 2008 Springer Science + Business Media, LLC. Manufactured in The United States</p><p>

6、<b>　　Abstract </b></p><p>　　Based on the IEEE 802.15.4 LR-WPAN specification, the ZigBee standard has been proposed to interconnect simple, low rate, and battery powered wireless devices. The dep

7、loyment of ZigBee networks is expected to facilitate numerous applications, such as home healthcare, medical monitoring, consumer electronics, and environmental sensors. For many of the envisioned applications, device mo

8、bility is unavoidable and must be accommodated. Thus, providing ubiquitous connections to/from a mobile device is</p><p>　　Keywords Mobility · Routing · ZigBee · IEEE 802.15.4 · Simulatio

9、n</p><p>　　A preliminary version of this paper was published in the Proceedings of the 2007 IFIP International Conference on Embedded and Ubiquitous Computing (EUC 2007) [9]. Since then, the paper has underg

10、one a major extension. Specifically, we have incorporated all the comments/ suggestions of the conference attendees into this version, and expanded nearly all the sections (especially Sections 1, 2, 3, and 4). As a resul

11、t, this journal submission is a much more thorough and authoritative presentation of</p><p>　　L.-J. Chen (B)</p><p>　　Institute of Information Science,Academia Sinica, Taipei, Taiwan e-mail: ccl

12、ljj@iis.sinica.edu.tw</p><p><b>　　T. Sun</b></p><p>　　PacketMotion, Inc., San Jose, CA, USA</p><p>　　N.-C. Liang</p><p>　　Google, Inc., Mountain View, CA, U

13、SA</p><p>　　Introduction</p><p>　　With wireless networking technologies permeating nearly every aspect of our working and living environments, simple appliances and numerous traditional wired se

14、rvices can now be efficiently connected wirelessly. This provides simple yet effective control/ monitoring convenience, while allowing very interesting applications to be developed on top of these wireless network-enable

15、d gadgets. The ZigBee standard[3], which is designed to interconnect simple devices, represents the latest attempt to re</p><p>　　ZigBee is a network and application layer specification developed by a multi-

16、vendor consortium called the ZigBee Alliance. Backed by more than 150 member companies, the ZigBee standard was ratified in late 2004, and released for public non-commercial use in June 2005. Although various ZigBee comp

17、liant product prototypes and application scenarios have been developed or defined by the industry, the performance and support facilities of ZigBee networks have not been thoroughly evaluated. </p><p>　　In a

18、n environment richly connected/embedded with ZigBee devices, major topological changes can occur due to device failures, mobility, and other factors. Device mobility is unavoidable in certain applications, such as the he

19、alth monitoring application for the elderly described in [4, 6], where a ZigBee enabled health monitoring sensor alerts the hospital, through a home ZigBee wireless network, if a health-related emergency occurs. The cons

20、equences could be disastrous if the ZigBee home network </p><p>　　Mobility is undoubtedly a part of the ZigBee vision, and it is important for the proper functioning of many envisioned ZigBee applications. S

21、ince mobility is anticipated and unavoidable, adequate mobility support is necessary to ensure ubiquitous connections among mobile devices. However, without a publicly available ZigBee routing implementation, no evaluati

22、on or additional development can be carried out by the research community. Furthermore, without ZigBee simulator support, it is difficult t</p><p>　　The contribution of this paper is threefold. First, to add

23、ress the research needs mentioned above, we present an original ZigBee network layer implementation (implemented in the NS-2 [2] network simulator) to facilitate additional research, evaluation, and development in this a

24、rea. Second, we identify existing provisions for accommodating ZigBee device mobility and assess their adequacy for dealing with different mobility scenarios. Third, we conduct a comprehensive set of preliminary simulati

25、on</p><p>　　The remainder of this paper is organized as follows.Section 2 provides an overview of the IEEE 802.15.4 and the ZigBee specifications. In Section 3, we discuss the routing and address allocation

26、mechanisms deployed in ZigBee mesh routing, and analyze the response of the routing protocol in basic mobility cases. In Section 4, we consider the ZigBee tree routing mechanism, and analyze the behavior of tree routing

27、in basic mobility scenarios. </p><p><b>　　Overview</b></p><p>　　2.1 IEEE 802.15.4</p><p>　　Based on the PHY and MAC layers specified by the IEEE 802.15.4 WPAN standard [

28、1], the ZigBee specification establishes a framework for the Network and Application layers. The protocol stack of ZigBee networks is shown in Fig. 1.</p><p>　　Figure 1 ：ZigBee protocol Stack in relation to

29、IEEE 802.15.4 standard.</p><p>　　In the PHY layer, IEEE 802.15.4 defines a total of 27 channels, namely: 16 channels with a data rate of 250 kbps on the license-free industrial scientific medical (ISM) 2.4–2

30、.4835 GHz band; 10 channels with a maximum data rate of 40 kbps on the ISM 902–928 MHz band; and 1 channel with a data rate of 20 kbps on the 868.0–868.6 MHz band. Meanwhile, in the MAC layer, IEEE 802.15.4 controls acce

31、ss to the radio channel by using the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mech</p><p>　　Two types of devices are specified in the IEEE 802.15.4 framework: a full function device (

32、FFD) and a reduced function device (RFD). An FFD generally has more responsibilities than an RFD because it must maintain routing tables, participate in route discovery and repair, maintain the beacon framework, and hand

33、le joining nodes. Moreover, an FFD can communicate with any other devices in its transmission range. In contrast, an RFD only needs to maintain a minimum amount of knowledge to stay in the </p><p>　　Figure 2

34、 Examples of IEEE 802.15.4 star and peer-to-peer topologies.</p><p>　　2.2 ZigBee Network Layer</p><p>　　Based on IEEE 802.15.4, the ZigBee Alliance specifies the standards for the network layer

35、and the application layer. Specifically, the ZigBee network layer defines how the network is formed and how the network address is assigned to each participating ZigBee node. Note that the assigned address is the only ad

36、dress for routing and data transmission in ZigBee networks. Three types of devices are defined in ZigBee: the ZigBee coordinator, ZigBee routers, and ZigBee end devices. An RFD can only be a</p><p>　　Every n

37、ode in a ZigBee network has two addresses: a 16-bit short network address and a 64-bit IEEE extended address. The 16-bit network address is assigned to each node dynamically by its parent coordinator/router when the node

38、 joins the network. This address is the only address used for routing and data transmission; it is analogous to the IP addresses used on the Internet. The extended address, on the other hand, is similar to an MAC address

39、, which is a unique identification of each device, an</p><p>　　There are two address allocation schemes for the 16- bit short network address in ZigBee networks: the static address allocation scheme and the

40、tree address allocation scheme. Both schemes work in a similar fashion in that the parent node assigns an address “block” to each of their child routers, which in turn allocate it to their respective descendent nodes. Th

41、e coordinator/router is responsible for maintaining the remaining number of free address spaces, the address block size, and the address</p><p>　　The ZigBee standard accommodates both mesh and tree topologie

42、s, which deploy different routing mechanisms, and respond differently to nodal mobility. Two routing schemes are available, namely ZigBee mesh routing and ZigBee tree routing, which we discuss in Sections 3 and 4 respect

43、ively.</p><p>　　Mobility Support in the ZigBee Mesh Topology</p><p>　　As mentioned in Section 2, coordinators/routers (FFDs) can actively participate in mesh routing, but end devices (RFDs) must

44、 rely on their parent nodes to perform the function on their behalf. Because of the unique properties of IEEE 802.15.4 and ZigBee networks (i.e., the address allocation structure and service assumptions), the performance

45、 bound of ZigBee mesh routing is expected to differ from the bounds of previous AODV [8] studies. </p><p>　　3.1 Mobile End Device</p><p>　　Since a ZigBee end device does not have routing capabil

46、ities, problems arise if it moves outside the range of its current parent router, and acquires another network address from a new parent router. Figure 3 illustrates two instances of the issue. </p><p>　　In

47、Fig. 3a, the mobile end device moves outside the range of its parent router, but the source node continues sending data to it. When the device fails to find its original parent router, it will associate with a new parent

48、 router and acquire a new network address. Since the end device can no longer be found via its “old” network address, data reception ceases completely, and it can not be recovered by any available ZigBee mesh routing mec

49、hanisms (i.e., route discovery). When the route cannot be</p><p>　　Figure 3b shows a scenario where the mobile end node acquires a new network address while it is sending data. In this case, data transmissio

50、n will be temporally disrupted until the mobile end node finds a new parent router to associate with. If the data flow is two-way, a route discovery and Device Discovery process would be triggered at the receiver (since

51、the source has changed its network address), and the disruption would be compounded. Even so, the situation would be recoverable, so long as</p><p>　　3.2 Mobile Router</p><p>　　ZigBee routers ac

52、tively participate in mesh routing by providing functionalities that maintain/repair routes that fail. Because of the built-in route recovery mechanism (via route discovery and route error identification), ZigBee routers

53、 are robust to the effects of most mobility cases, regardless of whether the failed node is sending or receiving data. After the router is assigned an initial network address, there is no need to change the address unles

54、s the tree address allocation scheme is use</p><p>　　Figure 3 a The source transmits data to the mobile destination, which moves at time (1), and acquires a new network address in the new location. The netwo

55、rk/application recovery mechanism is triggered and recovers the path. b The mobile source transmits data to a stationary destination. It then moves at time (1), and acquires a new network address in the new location, but

56、 data transmission is only interrupted temporally.</p><p>　　Mobility Support in the ZigBee Tree Topology</p><p>　　In the ZigBee tree topology, the network address is assigned according to a hier

57、archical tree structure, as specified in the tree address allocation method. Let Cm denote the maximum number of children allowed for each router, Rm denote the maximum number of routers a parent may have as child nodes,

58、 and Lm denote the maximum depth of the network. Suppose the network depth is d; then the n-th network address, An, can be derived as follows:</p><p>　　An = Aparent + Cskip(d) × Rm + n,

59、 (1)</p><p>　　where Cskip(d) is the maximum size of the allocated sequential addresses for the subtree rooted at the node of An and</p><p>　　.

60、(2)</p><p>　　After the network addresses have been assigned, each node can route packets to its upstream and downstream tree neighbors (parents and direct children) with the cluster tree routing algorithm, w

61、hich is similar to the cluster tree routing algorithm described in [5]. Trivially, every device in the network is a descendant of the ZigBee coordinator, and no device in the network is a descendant of any ZigBee end dev

62、ice. Each node checks the destination address of an incoming packet against its own ad</p><p>　　A < D < A + Cskip(d ? 1) (3)</p><p>　　N = A

63、 + 1 + [D ? (A + 1)/Cskip(d) ] × Cskip(d) (4)</p><p>　　When a node changes its parent router due to mobility, a new 16-bit network address will be assigned to the node au

64、tomatically to preserve the tree address/ routing structure. In many cases, the mobility of a router may cause cascading address changes across entire tree branches, and the effort required to maintain the tree address s

65、tructure may create various problems for ZigBee mobile devices. For example, the Device Discovery service in the application layer may have difficulty accommodating </p><p>　　4.1 Mobile End Device</p>

66、<p>　　In tree routing, end devices rely heavily on their parents to relay packets to the final destination. The routing nodes along the tree path use the tree routing algorithm to determine how to forward a packet.

67、 Whenever an end device moves outside the range of its current parent, it will seek a new parent node to associate with and obtain a new network address.</p><p>　　In simple mobility scenarios, if the end dev

68、ice is mobile while transmitting data, it will resume the transmission as soon as it acquires a new network address. If the data flow is two-way, a route discovery and Device Discovery process will be triggered at the re

69、ceiver (since the source has changed its network address). If the end device is receiving data, the data flow will eventually recover if the application is successful in using the Device Discovery mechanism to rediscover

70、 the node’s new </p><p>　　4.2 Mobile Router</p><p>　　ZigBee routers acting as parent nodes are responsible for forwarding packets to/from their descendant nodes, and thus play an important role

71、in hierarchical tree routing. In ZigBee tree topologies, new network addresses are assigned in accordance with Eq. 1 to ensure that the hierarchical tree structure is correct. The stability of this hierarchical addressin

72、g structure is crucial for the proper forwarding/delivery of packets.</p><p>　　For the above reasons, when a ZigBee router acquires a new parent router and a new network address, it may send a cascading netw

73、ork address change to all of its descendant nodes on the impacted branches. Depending on the number of affected nodes, cascading address changes could cause various levels of inconsistency in the tree address allocation

74、scheme, which would reduce the routing protocol’s ability to function properly. </p><p>　　Figure 4a shows a scenario where the mobile router moves outside the range of its original parent router and acquires

75、 a new network address. The mobile router can no longer be reached via its “old” network address; hence data reception will cease completely, and it will not be recoverable by any available ZigBee tree routing mechanisms

76、. Sometimes, these simple movements trigger major structural changes among the descendent nodes, and influence other flows as a consequence. Even with the Device D</p><p>　　If the mobile router is sending da

77、ta while it changes its parent router and acquires a new address, its “old” descendants must also change their network addresses, as shown in Fig. 4b. Depending on the number of nodes affected, a similar route failure to

78、 that in the cases mentioned would be experienced. Except in the simple mobility case, where only one or two nodes are moving within the network, the mobile router should be able to continue the data transmission after i

79、t acquires a new network a</p><p>　　Figure 4 a The source transmits data to a mobile destination, which moves at time (1), and acquires a new network address in the new location. Descendants of the “old” mob

80、ile destination must obtain new network addresses at time (2). b The mobile source transmits data to a stationary destination. It then moves at time (1) and acquires a new network address in the new location. The descend

81、ants of the “old” source need to acquire new network addresses at time (2).</p><p>　　Conclusion</p><p>　　Mobility is a critical component of various envisaged ZigBee applications. To ensure that

82、 mobile ZigBee devices can achieve ubiquitous connections to/from the ZigBee network, additional analyzes and evaluations must be performed. Our contribution in this paper is threefold. First, we provide an original impl

83、ementation of the ZigBee network layer in NS-2, which will allow additional research to be conducted in this area. Second, we assess the adequacy of current provisions for dealing with differ</p><p>　　Our re

84、sults indicate that when a network is static, both the mesh and the tree routing schemes work as intended, without incurring much packet loss. ZigBee end devices experience detrimental packet loss in almost all mobility

85、scenarios. The situation deteriorates further when there are multiple instances of mobility in the network, and when mobile nodes are traveling at high speed. In contrast, ZigBee routers typically suffer less packet loss

86、 when there is an intensive amount of mobility in the </p><p>　　Acknowledgements </p><p>　　We wish to thank the editors and anonymous reviewers for their insightful comments. This paper is based

87、 on work supported by the National Science Council under grant number NSC 95-2218-E-002-072 and the National Science Foundation under grant number ANI-0335302.</p><p>　　References</p><p>　　1. IE

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93、distance vector (AODV) routing. In: IETF RFC 3561, July.</p><p>　　9. Sun, T., Liang, N.-C., Chen, L.-J., Chen, P.-C., & Gerla, M.(2007) Evaluating mobility support in zigbee networks. In IFIP EUC.</p&

94、gt;<p>　　10. Zheng, J., & Lee, M.J. (2006) A comprehensive performance study of IEEE 802.15.4. Sensor network operations (Chapter 4, pp. 218–237). New York: IEEE, Wiley Interscience.</p><p>　　J Si

95、gn Process Syst (2010) 59:111–122</p><p>　　DOI 10.1007/s11265-008-0271-x</p><p>　　在ZigBee網(wǎng)絡(luò)中的移動性支持評估</p><p>　　Ling-Jyh Chen · Tony Sun · Nia-Chiang Liang</p><p&

96、gt;　　收稿日期：2008年4月13日 修訂：2008年8月6日 接受：2008年9月2日在線 發(fā)布時間：二零零八年十月十六日 ©2008施普林格科學(xué)+商業(yè)媒體，LLC</p><p><b>　　摘要</b></p><p>　　基于IEEE 802.15.4的LR-WPAN說明書中，ZigBee標(biāo)準(zhǔn)已經(jīng)提出來互連簡單，低速率和電池供電的無線設(shè)備。Zig

97、Bee網(wǎng)絡(luò)的部署將有利于多種應(yīng)用，如家庭保健，醫(yī)療監(jiān)控，消費電子產(chǎn)品，環(huán)境傳感器。對于許多的預(yù)想應(yīng)用程序，設(shè)備的移動性是不可避免的，并且必須得到滿足。因此，提供普遍存在的連接到移動裝置可用于各種未來ZigBee應(yīng)用是至關(guān)重要的。知識節(jié)點的移動性如何影響了ZigBee路由協(xié)議是非常重要的，但缺乏ZigBee模擬器支持限制了在這方面的研究，評估和開發(fā)量。迄今為止，研究人員一直無法通過大量的模擬影響進(jìn)行分析和評估移動應(yīng)用程序，。在本文中，我們

98、的貢獻(xiàn)是一舉三得。首先，我們目前的ZigBee網(wǎng)絡(luò)層中的NS-2，這將允許在該領(lǐng)域進(jìn)行了進(jìn)一步的研究和開發(fā)的初始實現(xiàn)。其次，我們分析目前的規(guī)定，是否足以應(yīng)付不同的流動性的情況。第三，我們提供了一套全面的展示了目前的標(biāo)準(zhǔn)來處理流動性的無效的仿真結(jié)果。我們的結(jié)果表明，該ZigBee設(shè)備在確定在移動場景中的路由性能顯著作用。</p><p>　　關(guān)鍵詞：移動、路由、ZigBee的IEEE 802.15.4、模擬<

99、/p><p>　　本文的初步版本發(fā)表于2007年IFIP國際會議嵌入式和普適計算（EUC2007）[9]。從此發(fā)生了大規(guī)模擴(kuò)建。特別是，我們已經(jīng)納入了與會者的所有意見到這個版本，并擴(kuò)展了所有的部分（尤其是第1，2，3和4）。這樣一來，本雜志提交的是一個更加全面和權(quán)威的展示我們的工作。</p><p><b>　　引言</b></p><p>　　隨

100、著無線網(wǎng)絡(luò)技術(shù)滲透到我們的工作和生活環(huán)境，簡單的電器和許多傳統(tǒng)有線服務(wù)的幾乎每一個方面，現(xiàn)在可以有效地連接無線。這提供了簡單而有效的控制/監(jiān)視的方便，同時允許對這些無線網(wǎng)絡(luò)功能的小工具的頂部開發(fā)非常有趣的應(yīng)用。ZigBee標(biāo)準(zhǔn)[3]，其被設(shè)計來互連簡單的設(shè)備，表示為實現(xiàn)此無線網(wǎng)絡(luò)的視野的最新嘗試。在商業(yè)環(huán)境中，ZigBee無線技術(shù)可以方便的設(shè)施和資產(chǎn)的更好的自動化管理。此外，還有許多ZigBee應(yīng)用為家庭器具的網(wǎng)絡(luò)，以及在家庭保健，醫(yī)療