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  • 學位論文

最佳化導航換手抉擇機制之研究

Research on Optimal Navigation Handover Decision Mechanism

指導教授 : 游張松
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摘要


近年來無線網路相關技術迅速發展普及,包涵了早期的類比式行動電話系統AMPS,而後的GSM、TDMA等,到目前已廣為接受的3G(WCDMA、CDMA2000等),使得無線行動電話系統跟我們的生活緊緊相關,近年來的WiFi無線網路更是興起一陣網路無線化的流行,推陳出新的無線網路標準,涵蓋範圍包含了從數公尺一直擴充到數英哩甚至數十英里。尤其最新提出的WiMAX技術宣稱能提供每秒75 Mbits 頻寬,並擁有理論值50公里的涵蓋範圍,其組織在之後所訂定的IEEE 802.16e,更為具有行動寬頻技術之最新標準。如此,在各種無線行動規格推陳出新與廣泛佈置之下,使得整個環境變得更為複雜,在都會城市中,許多建築物障礙物的屏蔽作用,導致其要達到行動無縫隙無線訊號的傳送接收更為困難。 在另一方面,許多歐美日的電信行動大廠對於此科技市場的管理策略,乃是佈署了重重的專利地圖,透過專利的授權與保護,不僅確保了此產業成為他們的cash cow來源,享受了收取權利金與開發市場產品的雙重利潤,也使得後來的競爭者想要進入此市場的機會愈趨細微。因此,台灣廠商能否在這個產業中,取得一席重要的地位,獲得與各國大廠談判的空間,相對日益重要,也是我們便是此項研究的主要動機與目的,希望能藉由從這個產業重要的需求著手,加上現在科技與資訊的配合,研發出一項真正具有取代性的關鍵技術。 基於上述的動機與原因,我們選擇了無線行動網路中最關鍵的換手抉擇問題,作為我們主要的研究目標,而在審視針對換手抉擇問題所提出的先前技術中,絕大部分都是基於行動裝置與基地台間的訊號噪音比與某個臨界值時作比較,若低於臨界值時,而有不同的換手抉擇作法與基地台目標選擇,然而,這些方式都會面臨以下兩大問題: 1. 在複雜的環境下,許多障礙物的阻隔,使其方法很難達到無接縫式的網路連結,即使可以也需要輸出大量的功耗。 2. 需不時地針對鄰近區的作Scan與Req,以期能掌握與更新鄰近基地台的資訊,相同地,也需要大量的能源。 因此,基於先前技術之種種缺失,我們著手此換手抉擇機制,配合現代資訊科技的發展,我們提出一個最佳式的導航換手抉擇機制,此方法的主要構思便是為行動裝置”畫好”當地附近一個基地台分布的地圖,有了這樣的地圖,行動裝置便能迅速且有效率的找出該換手抉擇的下一個基地台為何,而這些需求,藉由GPS全球定位系統的協助得以實現,讓能為行動裝置以最有效率、最節省能源的方式,尋找出該現行情境中最好的一個基地台。因此我們提出本論文主要的最佳化導航換手機制,包含了以下兩個主要方法: (1) 即時動態換手機制:利用現行科技環境,讓行動裝置在沒有之前路徑資料狀態下,藉由與HOT位址跟其他Indicator做定位,利用當時可得的前進方向與所在位置,進而選擇最佳的HOT基地台,達成換手選擇到較有效率的HOT,無論有無啟動導航的行動裝置皆可分別運作,計算出最佳的換手目標HOT。 (2) 狀態預設式導航換手機制:則是可以記錄並根據使用者(行動裝置)先前已走的路徑,作為現行使用者換手的參考,讓使用者無需再透過定址運算以及資料連結傳輸即可找到相對適合的HOT,並使用「有限狀態機」來實現此一導航機制,更可針對狀態做簡化,加速狀態搜尋與抉擇。為了避免以及加快屏障效應產生時的換手需求,我們也提出了「連線障礙清單」,利用此清單記錄各屏障發生的位址與換手的解決方案,讓之後再次來到此點時的使用者能提早預測屏障發生,並從清單中,找到換手的HOT解決目標。 藉由幾個情境分析,分別得到其最佳值的抉擇機制: 1. GPS導航機制啟用情境:在此情境,我們根據使用者設定的路徑,便可在需要的時候預先規劃最佳基地台給其行動裝置。 2. GPS定位機制啟用情境:在此情境,我們根據使用者當地附近所得之基地台地圖,做當地的最佳基地台規劃。 3. 其他定向機制啟用情境:可以設定於行道路線周遭或之上,藉由行動裝置的reader經讀取後更確定方向的選擇,規劃出該可能行徑方向的最佳基地台。 其次,我們也針對導航換手機制的方法再一次優化,提出所謂「狀態預存式導航換手」,主要理論在於利用每行動裝置之使用者有其固定或高度相關的軌跡模式,利用此特性,將以往行經的歷史連結記錄做參考,讓使用者無需再透過定址運算以及資料連結傳輸即可找到相對適合的基地台。 目前行動式無線網路市場仍處於萌芽期。其中的換手機制更是許多技術以及需要創新的突破。本篇論文藉由GPS及其他現行科技的配合,讓行動裝置與基地台之間的換手更為快速、省能,具有最佳化的抉擇機制,目前也正根據此構想進行專利申請,所具的獨特性、新穎性及整合性都在在說明了此專利的重要,也期待能與各國大廠在行動無線網路市場能爭有一席之地。

並列摘要


In recent years wireless network popularity of the rapid development of related technology, includes the early analog mobile phone system, AMPS, then the GSM, TDMA and so on, to the now widely accepted 3G (WCDMA, CDMA2000, etc.). The wireless mobile phone system with our lives closely related to the WiFi wireless network in recent years is the emergence of a popular wireless networking. New standards for wireless network coverage has been expanded from several dozens of miles and miles. In particular, WiMAX technology and the most recent claims provide bandwidth of 75 Mbits per second and have a theoretical value of 50 kilometers covered. The organization designs the IEEE 802.16e, the latest standards with mobile broadband technology. Nevertheless, in a variety of specifications for wireless operations under the new arrangement with a wide range, makes the whole environment have become more complex. In the metropolitan cities, many obstacles have shielding effect of buildings, resulting in difficulties to achieve seamless transmission of wireless signals. On the other hand, many European and American telecommunications market makers have aggressive actions on the wireless technology. The management of this technology strategy is the deployment of the many patent maps, through licensing and patent protection. As a result, it’s to ensure that this industry has become the source of their cash cow. They not only enjoy the right to charge market products and gain profits but also makes subsequent competitors attempting to enter this market become subtle. Therefore, it’s becoming more and more important that Taiwanese manufacturers in the industry can stand in a significant position and have the ability of control the powers to negotiate. And such study is our main motivation and purpose. We hope that from this important needs of industry, combining with information technology can develop a total new key invention. Based on the above-mentioned motives and reasons, we chose the most critical handover decision problem in wireless mobile network as our main research objectives. After examining the issues for handover decision in the prior art, we found out that most prior art were based on the signal to noise ratio (SNR) between mobile devices and base stations and comparing the SNR rate with a threshold value. While it’s less than the thrshold, many different handover decision practices and selects the handover to the target base station. However, these approaches will face the following two problems and issues: 1. In a complex environment, due to many unexpected obstacles blocking the ways, it’s very difficult to achieve seamless connection. Even so, the output can also consume a lot of power. 2. The need from time to time for the scans and the requests in nearby areas, not only acquires and updates information on the neighboring base station but also requires a large amount of energy. Therefore, based on the variety of drawbacks in previous inventions, we proceed the handover decision mechanism. With combining the development of modern information technology, we propose an optimal navigation handover decision mechanisms. The main idea of this method is to “draw a well-infomed local map” for a mobile device in terms of its nearby base stations. With such a map, a mobile device will be able to quickly and efficiently find the target handover to the next suitable choice of a base station. Basically, it only needs some positioning mechanism embedded in the system such as GPS, Global Positioning System or any other positioning means. Via the assistance, a mobile device can find out the best base station under current situation in a most energy efficient way. Through different scenario analysis, the best solution, respectively, by their choice of mechanism show as follows: 1. Navigation mechanism activation scenario: In this scenario, we can set the pre-planning the best base station to the mobile device based on the path the user attempts to navigate. 2. Positioning mechanism activation scenario: In this scenario, we can set best base station based on user’s local position map of base stations. 3. Other mechanism activation scenario: Different from 2nd scenario, we adopt other technologies such as RFID, etc. to assist the positioning/direction (noted as Lane Indicator) by a mobile device. Via communicating with the Line Indicator, handover decision can be made based on the direction of the mobile device. Secondly, we further optimize the navigation handover decision method. It’s the so-called "prestored navigation handover". The main theory relies on each user has a fixed or highly relevant to itself track model. We can utilize the characteristics of the past record and the history of track as a reference. Therefore users don’t need to do address computing and information through the transmission link with the base station. At present, mobile wireless network market is still in its emerging period, the majority of applications are mainly for voice transmission while data transmission or multimedia content is widely used gradually. Handover decision mechanism is in the need of innovation for a number of technical breakthroughs. This papers utilizing GPS and other current technology enables the handover decision between mobile devices and base stations to be more rapid and energy-saving. Based on the mechanism, we can file the patent application with its unique, innovative and integrated features for the concept. Also we look forward to competing with other major wireless network companies in the market.

參考文獻


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