【正文】 務(wù)中心是與 ATamp。T 公司和 Verizon 公司的都不同。它的設(shè)備重新連接網(wǎng)絡(luò)時 ,只能容納從序列號從 1 開始的 30 條短信。因此 , 斯普林特公司的短消息服務(wù)中心只能存儲 30 條短信，也遵循先入先出的規(guī)則。 當(dāng)終端設(shè)備的短信緩存區(qū)是滿的，網(wǎng)絡(luò)中的短信被保留在短消息服務(wù)中心的緩存中。在這種情況下，與 全球移動通信系 統(tǒng) 的標(biāo)準(zhǔn)一樣，移動手機(jī)會從歸屬位置寄存器返回一個基站緩存溢出標(biāo)志。由于歸屬位置寄存器不可能確定每一個手機(jī)的收件箱容量，因此，我們選擇了不同時期不同價格的手機(jī)進(jìn)行測試： 美國電話電報公司 的 Nokia 3560 手機(jī)、 弗萊森電訊 的稍新一點(diǎn)的 LG 4400 手機(jī) 和斯普林特公司最近發(fā)布的高端Treo 650 手機(jī)，包含 1GB 的可移動的記憶棒 。 移動設(shè)備的能力可以通過緩慢地發(fā)送畢業(yè)設(shè)計（論文） 外文翻譯 5 信息到目標(biāo)用戶，使目標(biāo)用戶的整個收件箱出現(xiàn)警告指示來觀察。 表 所示是不同移動設(shè)備緩沖能力的結(jié)果值。 表 SMS移動設(shè)備容量 發(fā)送 規(guī)則實驗結(jié)果指明 手機(jī)短信服務(wù) 系統(tǒng)是如何對大量涌入的文本信息作出反應(yīng)。我們確信大多數(shù)短消息服務(wù)中心和移動設(shè)備的緩沖容量有限。倘若發(fā)生拒絕服務(wù)攻擊，大量短信涌入造成短信的丟失。因此，拒絕服務(wù)攻擊要成功，必須有分布式的大量用戶。 畢業(yè)設(shè)計（論文） 外文翻譯 6 Exploiting Open Functionality in SMSCapable Cellular Networks 1． SMS/CELLULAR NETWORK OVERVIEW This section offers a simpli?ed view of an SMS message traversing a GSMbased system from submission to delivery. These procedures are similar in other cellular works including CDMA. Submitting a Message There are two methods of sending a text message to a mobile device via another mobile device or through a variety of External Short Messaging Entities (ESMEs). ESMEs include a large number of diverse devices and interfaces ranging from and webbased messaging portals at service provider websites to voic services, paging systems and software applications. Whether these systems connect to the mobile phone work via the Inter or speci?c dedicated channels, messages are ?rst delivered to a server that handles SMS traf?c known as the Short Messaging Service Center (SMSC). A service provider supporting text messaging must have at least one SMSC in their work. Due to the rising popularity of this service, however, it is being increasingly mon for service providers to support multiple SMSCs in order to increase capacity. Upon receiving a message, the contents of ining packets are examined and, if necessary, converted and copied into SMS message format. At this point in the system, messages from the Inter bee indistinguishable from those that originated from mobile phones. Messages are then placed into an SMSC queue for forwarding. Routing a Message The SMSC needs to determine how to route messages to their targeted mobile devices. The SMSC queries a Home Location Register (HLR) database, which serves as the permanent repository of user data and includes subscriber information (. call waiting and text messaging), billing data, availability of the targeted user and their current location. Through interaction with other work elements, the HLR determines the routing information for the destination device. If the SMSC receives a reply stating that the current user is unavailable, it stores the text message for later delivery. Otherwise, the response will contain the address of the Mobile Switching Center (MSC) currently providing service. In addition to call routing, MSCs are responsible for facilitating mobile device authentication, location management for attached base stations (BS), performing handoffs and acting as gateways to the Public Switched Telephone Network (PSTN). 畢業(yè)設(shè)計（論文） 外文翻譯 7 When a text message arrives from the SMSC, the MSC fetches information speci?c to the target device. The MSC queries a database known as the Visitor Location Register, which returns a local copy of the targeted device’s information when it is away from its MSC then forwards the text message on to the appropriate base station for transmission over the air interface. A diagram of a mobile phone work is depicted in Figure , followed by a simpli?ed SMS message ?ow in Figure . Figure SMS Network Figure Simplified examples of an SMS Network and message flow Wireless Delivery The air interface is divided into two parts the Control Channels (CCH) and Traf?c Channels (TCH). The CCH is further divided into two types of channels the Co