标题: | 无线细胞网路中整批更新及以移动方向为主的位置 Batch-Update and Direction-Based Location Tracking Schemes in Wireless Cellular Networks |
作者: | 黄汉文 Hang-Wen, Hwang 曾建超 Chien-Chao Tseng 资讯科学与工程研究所 |
关键字: | 个人通讯网路;行动终端机;注册;通讯连接;位置更新;终端机呼叫;PCS networks;mobile terminal;registration;call delivery;location update;terminal paging |
公开日期: | 2002 |
摘要: | 在个人通讯网路的移动管理中,位置追踪是最重要的课题之一。目前的移动管理标准像EIA/TIA IS-41 和 ETSI GSM MAP 都是以单一home location register (HLR) 和多个visit location registers (VLRs)的两阶层架构来追踪使用者。在这种HLR/VLRs两阶层架构下,当使用人口不断增加时,单HLR可能变成网路执行位置追踪及通讯连接(call delivery)的瓶颈。为了解决单HLR的瓶颈问题,已经有一些研究提出多HLRs的方法来降低网路的传输交通及通讯接通的时间。但无论的如何,多HLRs的方法会因每个HLRs需要资料同步更新而产生额外负担。在本论文的第一部分,我们提出在分散式HLRs架构下整批更新的方法,而非立即更新,来降低网路传送讯号的负担。实验数据显示,和IS-41标准相比,分散式HLRs架构可以有效减少网路上位置注册及通讯连接所需的传送成本。而我们整批更新的方法则可以进一步降低HLRs资料同步更新的额外负担。 另一方面,我们知道网路中使用者的位置更新与呼叫(location update and paging)存在着成本折冲。很多研究纷纷提出使位置更新与呼叫成本最佳化的方法,其中大多数的研究都致力于发展个人化的方法,也就是根据使用者移动模式来动态调整位置更新与呼叫动作的方法。但,根据最近研究结果发现,正常状况下,大多数的使用者会因某种目的而朝向特定地方移动,并非毫无目的的随意走,而这个观察结果目前尚未被利用。在本论的第二部分,我们提出一个当使用者改变移动方向时就必须作位置更新的方法。因为这个以移动方向为主的方法可以有效利用移动者向前移动倾向的特性,因此可以降低位置更新与呼叫动作的讯号传送成本。实验数据显示,在正常移动模式下,我们以移动方向为主的方法表现得比以距离为主的方法来得好。 Location tracking is one of the most important issues of mobility management in Personal Communication System (PCS) networks. Current mobility management standards, such as EIA/TIA IS-41 and ETSI GSM MAP, employ a two-level architecture of location databases with a single home location register (HLR) and visit location registers (VLRs) architecture for tracking the locations of mobile subscribers. In the two-level HLR/VLRs architecture, the single HLR may become the bottleneck in location tracking or call setup procedures as the number of mobile subscriber increases. In order to resolve the bottleneck problem of the single HLR architecture, several researchers have proposed multiple HLR schemes to reduce both signal traffics and/or call setup time. However, multiple HLR schemes incur extra signaling in updating multiple HLR databases. In the first part of this thesis, we propose a batch-update strategy, instead of the immediate update method, to reduce the signaling overhead for the location tracking schemes with replicated location information. The numerical results show that the distributed HLRs architecture, compared with the IS-41 standard, can effectively decrease the signaling cost of location registration and call delivery, and our batch-update approach can further reduce the multiple HLR update overhead incurred by the immediate update method. On the other hand, it is well known that there is a trade-off between location update and paging. Many researchers have proposed different location update strategies in order to optimize the signaling cost of location update and/or paging procedure. Most of the previous research efforts focus on the per-user-based schemes that dynamically adjust the location update and paging operations according to the moving pattern of mobile subscribers. However, according to some recent research results, the majority of users normally move toward a specific target with a particular purpose, instead of “walking” in a random way, which has not been exploited in the previous investigations. In the second part of this thesis, we propose a novel location tracking approach that performs a location update when the mobile changes its direction of movement. Since the direction-based approach can utilize effectively the forward-prone moving characteristic of the mobile subscribers, it can reduce the signal cost of both location update and paging procedure. Our numerical result shows that the direction-based approach outperforms the most recognized distance-based scheme for the mobile subscribers with normal-walking behavior. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT910392105 http://hdl.handle.net/11536/70167 |
显示于类别: | Thesis |