<acronym id="6i0ao"><small id="6i0ao"></small></acronym>
<acronym id="6i0ao"><center id="6i0ao"></center></acronym>
歡迎來到文庫吧! | 幫助中心 堅持夢想,走向成功!
文庫吧
首頁 文庫吧 > 資源分類 > DOC文檔下載
 

外文翻譯----4G異構網絡的切換-其他專業.doc

  • 資源ID:7452       資源大小:420.00KB        全文頁數:13頁
  • 資源格式: DOC        下載權限:游客/注冊會員/VIP會員    下載費用:10
換一換
游客快捷下載 游客一鍵下載
會員登錄下載
下載資源需要10元   |   0.1元文檔測試下載

支付方式: 微信支付    支付寶   
驗證碼:   換一換

      加入VIP,下載共享資源
 
友情提示
2、PDF文件下載后,可能會被瀏覽器默認打開,此種情況可以點擊瀏覽器菜單,保存網頁到桌面,既可以正常下載了。
3、本站不支持迅雷下載,請使用電腦自帶的IE瀏覽器,或者360瀏覽器、谷歌瀏覽器下載即可。
4、本站資源下載后的文檔和圖紙-無水印,預覽文檔經過壓縮,下載后原文更清晰   

外文翻譯----4G異構網絡的切換-其他專業.doc

Handoffs in Fourth Generation Heterogeneous Networks Nidal Nasser, University of Guelph Ahmed Hasswa and Hossam Hassanein, Queen’s University 4G異構網絡的切換 加拿大安大略省圭爾夫大學 加拿大安大略省皇后大學 ABSTRACT As mobile wireless networks increase in popularity and pervasiveness, we are faced with the challenge of combining a diverse number of wireless networks. The fourth generation of wireless communications is expected to integrate a potentially large number of heterogeneous wireless technologies in what could be considered a huge step forward toward universal seamless access. One of the main challenges for seamless mobility is the availability of reliable horizontal intrasystem and vertical intersystem handoff schemes. Efficient handoff schemes enhance quality of service and provide flawless mobility. This article presents different and novel aspects of handoff and discusses handoff related issues of fourth generation systems.Desirable handoff features are presented. Handoff decisions, radio link transfer, and channel assignment are described as stages of the complete handoff process. A vertical handoff decision function, which enables devices to assign weights to different network parameters, is also presented. 摘要 移動無線網絡日益盛行之時,不同網絡之間融合的挑戰擺在面前。4G無線通信整合了大多數異構網絡的無線技術,在走向通用的無縫接入方面邁向了一大步。無縫移動通信面臨的主要挑戰之一是可靠的水平網間切換和垂直網內切換機制的有效性。有效的切換機制提高了服務質量提供了無縫移動通信。本文提出了新穎不同的切換并討論了4G切換的相關問題。本為給出了令人滿意的切換特性。切換判決,無線鏈路傳輸和信道分配在整個切換過程中分步描述。本文還給出了一種能夠讓終端去分配權重給不同網絡參數的垂直切換判決函數。 INTRODUCTION 1.介紹 First, second- and third-generation mobile systems depended on the employment of the radio spectrum that was either unlicensed available for public use or licensed for use by a very small number of service providers and network operators in each region. Differences in bandwidth and coverage areas have led to the necessity of developing multi-network interface devices terminals that are capable of using the variety of different network services provided. 首先,第二代第三代移動通信系統依賴于無線頻譜的利用,這些頻譜要么被公共使用要么被批準在各個地區由一些小數量的服務提供商和網絡運營商使用。帶寬和覆蓋范圍的差異導致發展多網絡接口終端的必要性,多網絡接口終端可以使用不同網絡服務提供的多樣性。 The fourth generation 4G of wireless communications is expected to integrate a potentially large number of different heterogeneous wireless technologies in what could be considered a huge step forward toward universal wireless access and omnipresent computing through seamless mobility [1]. Even though 4G is currently undefined,there are many current outlooks that delineate the vision of the new wireless technologies.Based on the emergent trends of mobile communication, 4G will have larger bandwidth, higher data rates, smoother and quicker handoff, and will focus on reducing faultless service and allowing seamless handoff across a multitude of wireless networks. The key concept is integrating the 4G capabilities with all of the existing mobile technologies. Network management will be necessary among different access systems in terms of horizontal intrasystemand vertical intersystem handoff as well as seamless mobility, quality of service, dependability,and security. 4G無線通信融合了大多數異構網絡的無線技術,在通用的無縫接入方面和通過無縫移動通信進行泛在計算方面邁向了一大步[1]。即使4G當前沒有明確定義,仍然有很多當前的展望描述了新一代無線技術的景象。基于移動通信浮現的趨勢,4G擁有更多的帶寬和數率以及更平滑快捷的切換,集中致力于減少差錯服務和允許通過多種無線網絡的無縫切換。關鍵概念是使用已存在的移動技術整合4G性能。網絡管理,對于不同的接入系統如垂直和水平切換還有無縫移動性、服務質量、可靠性和安全性,很有必要。 The remainder of this article is organized as follows. We present a novel classification hierarchy for handoffs. A comprehensive study of various handoff decision factors in heterogeneous wireless networks is explained. We then explain and qualitatively evaluate the proposed vertical handoff decision function VHDF. We provide a performance evaluation of the described solution.Finally, an article summary is given. 下面的文章內容如下。給出了一種新的用于切換的分類層次。對異構無線網絡中各種切換判決因子的全面研究進行解釋,解釋和定量地評估本文提到垂直切換函數VHDF。提供所述解決方案的性能評估及文章概要。 CLASSIFICATION OF HANDOFFS 2.切換的分類 In principle, each mobile terminal node is, at all times, within range of at least one network access point, also known as a base station. The area serviced by each base station is identified as its cell. The dimensions and profile of every cell depend on the network type, size of the base stations,and transmission and reception power of each base station. Usually, cells of the same network type are adjacent to each other and overlap in such a way that, for the majority of time,any mobile device is within the coverage area of more than one base station. Cells of heterogeneous networks, on the other hand, are overlaid within each other. Therefore, the key issue for a mobile host is to reach a decision from time to time as to which base station of which network will handle the signal transmissions to and from a specific host and handoff the signal transmission if necessary. 大體上,每個移動終端節點總是歸類于至少一種網絡接入點即基站。每一個基站的服務區定義為它的小區。每個小區的大小和外形依賴于網絡類型、基站大小、基站的傳輸和接收功率。通常相同類型的小區以這樣一種方式彼此相鄰和重疊,大多數時間內任一移動終端所處的覆蓋面積超過一個基站。另一方面,異構網絡的小區相互覆蓋。因此,移動主機的關鍵問題是要時不時地做出選擇,哪個網絡的哪個基站來處理具體移動主機的信號傳輸和接收以及必要時切換信號的傳輸。 We classify handoffs based on several factors as shown in Fig. 1. No longer is the network type the only handoff classification factor. Many more factors constitute categorization of handoffs including the administrative domains involved, number of connections and frequencies engaged. The following are categorization factors along with the handoff classifications that are based on them. 如圖1所示,基于幾種因素給出了切換的分類。網絡類型不再是唯一的切換分類的因素。這個切換的分類因素有很多組成包含涉及的管理區域、連接和使用的頻率數。下圖是基于它們的切換類型的分類因素。 圖1切換的分類樹 FIRST FACTOR NETWORK TYPES INVOLVED This is the most common classification factor.Handoffs can be classified as either horizontal or vertical. This depends on whether a handoff takes place between a single type of network interface or a variety of different network interfaces. Horizontal handoff the handoff process of a mobile terminal between access points supporting the same network technology. For example,the changeover of signal transmission as themobile terminal moves around from an IEEE 802.11b base station to a geographically neighboring IEEE 802.11b base station is considered as a horizontal handoff process. Vertical handoff the handoff process of a mobile terminal among access points supporting different network technologies. For example, the changeover of signal transmission from an IEEE 802.11b base station to an overlaid cellular network is considered a vertical handoff process.Horizontal and vertical handoffs are discussed in more detail in the following sections. 2.1因素一 涉及的網絡類型這是最普遍的分類因素。切換能被分為水平切換或者垂直切換。這主要看切換是發生在同種網絡類型之間還是不同網絡類型之間。 水平切換移動終端在支持相同網絡技術的接入點之間的切換過程,例如,從802.11b基站到地理上相鄰802.11b基站的信號傳輸的轉變就是水平切換過程。 垂直切換移動終端在支持不同網絡技術的接入點之間的切換過程,例如,從802.11b基站到重疊覆蓋蜂窩網絡的信號傳輸的轉變就是垂直切換過程。水平和垂直切換在后面的章節中會詳細討論。 SECOND FACTOR FREQUENCIES ENGAGED Intrafrequency handoff the handoff process of a mobile terminal across access points operating on the same frequency. This type of handoff is present in code-division multiple access CDMA networks with frequency-division duplex FDD. Interfrequency handoff the handoff process of a mobile terminal across access points operating on different frequencies. This type of handoff is present in CDMA networks with time-division duplex TDD and is the only handoff type supported in GSM cellular systems. 2.2因素二使用的頻率 頻間切換移動終端穿越在相同頻率上運行的接入點之間的切換過程。這種切換的典型例子就是FDD的CDMA網絡。 頻內切換移動終端穿越在不同頻率上運行的接入點之間的切換過程。這種切換的典型例子就是TDD的CDMA網絡和只支持GSM蜂窩系統的切換類型。 THIRD FACTOR NUMBER OF CONNECTIONS INVOLVED Handoffs can be classified as hard, soft, or softer. Hard handoff In a hard handoff the radio link to the old base station is released at the same time a radio link to the new base station is established. In other words, using hard handoff,a mobile node is allowed to maintain a connection with only one base station at any given time. Soft handoff Contrary to hard handoffs, in a soft handoff a mobile node maintains a radio connection with no less than two base stations in an overlapping handoff region and does not release any of the signals until it drops below a specified threshold value. Soft handoffs are possible in situations where the mobile node is moving between cells operating on the same frequency. Softer handoff A softer handoff is very similar to a soft handoff, except the mobile terminal switches connections over radio links that belong to the same access point. 2.3因素三涉及連接數 切換被分為硬切換,軟切換和更軟切換。 硬切換在硬切換中,目標基站無線鏈路建立的同時釋放原基站的無線鏈路。也就是說,使用硬切換時,在任何時間,移動節點只能同一個基站保持連接。 軟切換與硬切換相比,在軟切換中,移動節點在重疊覆蓋的切換區內和不少于2個基站保持連接,并且不會釋放任何信號直到某信號低于給定的閥門值。當移動節點在相同頻率上運行的小區間移動時可能會發生軟切換。 更軟切換除了移動終端在同一個接入節點的無線鏈路上交換連接這點特性之外,更軟切換同軟切換很類似。 FOURTH FACTOR ADMINISTRATIVE DOMAINS INVOLVED An administrative domain is a group of systems and networks operated by a single organization of administrative authority. Administrative domains play a significant role in 4G wireless networks as different networks, each controlled by different administrative authorities, become available. Consequently, the classification of handoffs in terms of administrative domains is a crucial issue. Intra-administrative handoff a handoff process where the mobile terminal transfers between different networks supporting the same or different types of network interfaces managed by the same administrative domain. Inter-administrative handoff a handoff process where the mobile terminal transfers between different networks supporting the same or different types of network interfaces managed by different administrative domains. 2.4因素四涉及的管理區域 管理區域是由同一個管理者管理的一組系統和網絡。管理區域在4G無線網絡如不同的網絡中扮演重要的角色,不同的網絡都有不同的管理者。因此,根據管理區域劃分的切換類型是一個很重要的研究問題。 管理域之內的切換移動節點在相同管理域管理的不同網絡支持相同或不同類型網絡接口之間切換過程。 管理域之間的切換移動節點在不同管理域管理的不同網絡支持相同或不同類型網絡接口之間切換過程。 FIFTH FACTOR NECESSITY OF HANDOFF Handoffs can be classified based on need. Obligatory handoff In some situations it is necessary for the mobile terminal to transfer the connection to another access point in order to avoid disconnection. Voluntary handoff In other situations transfer of connection is optional and may or may not improve the quality of service.Voluntary and obligatory handoffs are discussed in more details later on. 2.5因素五切換的必要性 基于需要而劃分的切換 強制切換在有些情況下,為了避免掉線,有必要將移動終端的連接轉移到另一個接入點。 自愿切換在其他情況下,連接的轉移是可選擇的,對于提高服務質量不確定。自愿切換和強制切換在以后的章節中詳細討論。 SIXTH FACTOR USER CONTROL ALLOWANCE Handoffs can be classified as proactive or passive. Proactive handoff In a proactive handoff the mobile terminal’s user is allowed to decide when to handoff. The handoff decision can be based on a set of preferences specified by the user.Proactive handoff is expected to be one of the radical features of 4G wireless systems. Passive handoff The user has no control over the handoff process. This type of handoff is the most common in first-, second-, and third-generation wireless systems. 2.6因素六用戶控制允許 切換可分為主動的和被動的。 主動切換在主動切換中,移動終端用戶可以選擇何時切換。這種切換判決基于用戶事先設定好的參數。主動切換是4G無線網絡系統的基本特點之一。 被動切換用戶不控制切換過程。這種類型的切換在前3代無線通信系統中最為普遍。 HANDOFFS IN 4G HETEROGENEOUS NETWORKS 3. 4G異構網絡的切換 As discussed above, handoffs can be defined as the transition of signal transmission between different cells. A handoff scheme is required to preserve connectivity as devices move about, and at the same time curtail disturbance to ongoing transfers. Therefore, handoffs must exhibit low latency, sustain minimal amounts of data loss, as well as scale to large networks. Handoff schemes have been thoroughly researched and deployed in cellular systems, also known as wireless wide area networks WWANs, and are escalating in importance in other networks, such as wireless LANs WLANs, as research in 4G wireless communications increases in popularity. Handoffs can be classified as either horizontal or vertical,as depicted in Fig. 2. 如上面討論的,切換可以定義為不同小區之間傳輸信號的轉移。切換機制要求當設備移動時保持連接性,同時對正在進行的轉移減少干擾。因此,切換必須表現出低的反應時間,保持最小的數據丟失和測量大的網絡。切換機制在蜂窩網絡中已經徹底地研究和配置過,比如無線廣域網WWANs,在無線局域網WLANs中的重要性也逐漸提高。如圖2,切換可劃分為水平切換和垂直切換。 Horizontal handoff is the changeover of signal communication from one base station to a geographically neighboring base station supporting the same technology, as the user roams about. Horizontal handoff is also referred to as intra-technology handoff. Every time a mobile cellular host crosses from one cell into a neighboring cell supporting the same technology,the network routinely and automatically exchanges the coverage responsibility from one base station to another. Each base station change, as well as the exchange procedure or method is known as horizontal handoff. In a properly operating network, handoff takes place smoothly and efficiently, without gaps in communications and without uncertainty as to which base station should be dealing with the mobile node. Mobile users need not get involved in order for horizontal handoff to take place nor do they have to sense the handoff process or identify which base station is managing the signals at any certain time. 水平切換是從一個基站到地理上相鄰且支持相同技術基站的信號傳輸的轉變,如用戶漫游時。水平切換也被當作技術內切換提及。每當一個移動蜂窩主機從一個小區穿越相鄰小區支持相同技術,網絡通常會自動地從一個基站到另一個基站交換覆蓋責任。每一次基站的改變,還有交換手續和方法都認為是水平切換。在一個運行良好的網絡中,切換會平滑而有效的發生,沒有通信上的不通暢,也沒有不確定性,即不知道哪個基站應該接管這個移動節點。移動用戶不需要涉及水平切換的發生,對切換過程也沒有感覺,在任何時間也不涉及識別到底哪個基站正在處理信號。 Horizontal handoff is the most widespread definition of handoff due to the extensive research that has taken place in this field in the last several years. Vertical handoff, on the other hand is a more recent and exciting scheme that promises to transfigure the way we communicate.While horizontal handoff is a handover among base stations in service by the same wireless network interface, vertical handoff takes place between different network interfaces that usually represent different technologies [2]. Vertical handoff architectures and schemes will play a major role in the IEEE 802.21 standard and shall pave the road for emergence of 4G overlay multinetwork environments. 水平切換是范圍最為廣泛的切換定義,是由于其在這個領域里的廣泛研究在最近很多年一直在進行。另一方面,垂直切換更多的是最近提出而令人振奮的切換機制,讓大家感覺將來的通信方式會很美好。水平切換是處于相同無線網絡接口服務的基站之間的切換,而垂直切換發生在不同網絡接口之間,這些接口通常代表了不同的技術[2]。垂直切換體系和機制在IEEE 802.21標準中將扮演主要角色,并為4G重疊多網絡環境的融合鋪平道路。 There are two types of vertical handoffsupward and downward. An upward vertical handoff [3] is roaming to an overlay with a larger cell size and lower bandwidth such asWANs cellular networks, and a downward vertical handoff is roaming to an overlay with a smaller cell size and larger bandwidth. Downward vertical handoffs are less time critical, since a mobile device can always remain connected to the upper overlay and not handoff at all. 有兩種垂直切換類型向上和向下。向上垂直切換[3]是漫游到一個覆蓋更大帶寬較低的區域如蜂窩網絡,向下垂直切換是漫游到一個覆蓋更小帶寬較大的區域。向下垂直切換的時間急迫性較小,因為移動設備能總是保持同更大覆蓋網絡的連接而可以不切換。 SEAMLESS HANDOFF In one of the revolutionary drivers for 4G, technologies will complement each other to provide ubiquitous high-speed wireless connectivity to mobile terminals [4]. In such an environment, it will be necessary to support seamless handoffs of mobile terminals without causing disruption to their ongoing sessions. As a result, the need for seamless handoff across the different wireless networks is becoming increasingly

注意事項

本文(外文翻譯----4G異構網絡的切換-其他專業.doc)為本站會員(天天文庫)主動上傳,文庫吧僅提供信息存儲空間,僅對用戶上傳內容的表現方式做保護處理,對上載內容本身不做任何修改或編輯。 若此文所含內容侵犯了您的版權或隱私,請立即通知文庫吧(發送郵件至[email protected]或直接QQ聯系客服),我們立即給予刪除!

溫馨提示:如果因為網速或其他原因下載失敗請重新下載,重復下載不扣分。




關于我們 - 網站聲明 - 網站地圖 - 資源地圖 - 友情鏈接 - 網站客服點擊這里,給文庫吧發消息,QQ:1548881058 - 聯系我們

[email protected] 2015-2021 wenkub網站版權所有
經營許可證編號:鄂ICP備17016276 

收起
展開
北京pk10双面盘预测
<acronym id="6i0ao"><small id="6i0ao"></small></acronym>
<acronym id="6i0ao"><center id="6i0ao"></center></acronym>
<acronym id="6i0ao"><small id="6i0ao"></small></acronym>
<acronym id="6i0ao"><center id="6i0ao"></center></acronym>