WiMAX

Intro

Scope

Usage

What is WiMax?

What is 802.11n?

Evolution

802.16 Spectrum

802.11 vs. 802.16 Spectrum

Spectrum Proposal

WiMax's Problem

Comparison of 802.11 and 802.16

802.16 Specification

Multi-Path Problem

OFDM

OFDM

Architecture of WiMAX networks

How WiMAX Work?

How WiMAX Work?

How WiMAX Work?

How WiMAX Work?

How WiMAX Work?

How WiMAX Work?

How WiMAX Work?

Vertical Handoff

Hierarchical micro-mobility

Hierarchical micro-mobility

Fast handoff

Prototype - Handoff Procedure

Prototype - Software modules

Images

WiMAX News

WiMAX Versions

Untitled Document
Intro
全名 Worldwide Interoperability for Microwave Access
緣起
   
為了讓802.16能夠順利發展，Intel、Nokia、Proxim、Wi-LAN與Fujitsu等廠商更於2003年初共同成立了一個非營利組織WiMAX，這個組織主要在驗證各家業者IEEE 802.16x設備的相容性，以推廣IEEE 802.16x的發展。
任務 協助推動無線寬頻存取設備之間的相容性與互通性
   
類似 802.11 之Wi-Fi Alliance 角色
主旨
   
於全球宣揚與推廣 802.16 之相關標準、達到最終消費者使用其作為無線寬頻上網之標準規格
   
提出與802.16相關標準符合之終端 access profiles標準
   
互通性認證、 促進使用寬頻無線接取、 發展及提出相容性測試規格
 
其會員分為首要會員(Principal)、一般性會員(Regular)與服務供應商會員(Service Provider) ，目前共有一百多個會員包括
   
英國電信（BT）、英國寬頻（UK Broadband）、西班牙Iberbanda、墨西哥MVS Net、巴西Neotec、香港電訊盈科（PCCW）、法國電信、Qwest通信公司、XO通信以及印度的Reliance Infocomm等電信公司。
Wed Mar 16 00:33:10 CST 2011

Untitled Document
Scope
Wed Mar 16 00:33:11 CST 2011 Untitled Document
Usage
Wed Mar 16 00:33:12 CST 2011 Untitled Document
What is WiMax?
WiMax (Worldwide Interoperability for Microwave Access)
 
IEEE 802.16
   
目前最新版本為802.16-2004(RevD)
   
802.16e(Mobile WiMAX)
 
為了解決「Last Mile」的難題
 
使用的頻段為2~11GHz，未來以3.5GHz 為主
 
頻寬傳輸速度最大70Mbps
 
最遠可及30miles(約48km)，最佳在3~5miles
 
傳輸功率約在1000W
 
使用3DES或AES加密，然後再加上EAP，這種方法叫PKM-EAP
 
於2003年制訂規格，
   
支援這項標準的主要有Intel、Alvarion、三星、富士通、Nokia、西門子等公司。
Wed Mar 16 00:33:13 CST 2011 Untitled Document
What is 802.11n?
 
802.11n (WiFi)
 
802.11n速度可能為54Mbps，
 
距離因功率而有不同,目前是300m，可望到1km以上，
 
功率約1mW~100mW，為WiMax的千萬分之一
 
802.11n並沒有規範 Security (只有規範PHY與MAC層)
Wed Mar 16 00:33:14 CST 2011 Untitled Document
Evolution
Wed Mar 16 00:33:15 CST 2011 Untitled Document
802.16 Spectrum
Wed Mar 16 00:33:16 CST 2011 Untitled Document
802.11 vs. 802.16 Spectrum
Wed Mar 16 00:33:17 CST 2011 Untitled Document
Spectrum Proposal
 
WiMAX這項技術的主要問題之一是在能否在有執照頻譜上使用。
   
問題是有執照頻譜包含了各種不同的頻帶，每個頻帶都有自己獨有的功能， 並且在傳輸特性和功率要求上有很大不同，不同的有執照頻譜不 僅僅是按照頻譜圖分佈， 而是按照地理位置進行分配。各個國家的無線頻譜資源都不一樣。 甚至於相同的頻譜，不同的國家規定的用途也是不一樣的
 
“混雜的頻譜問題很難解決，也不存在一條便捷的途徑。”
   
WiMAX論壇副主席兼奧維通商務發展助理副總裁Mohammed Shakouri指出， “我們正在選擇一些符合全球需求的頻段，並且我們已經成立了一個協調組織， 來協調這些矛盾。”。
歐洲
 
愛爾蘭就是重新分配3.5GHz頻段的國家之一，它收回了閒置多年的3.5GHz頻譜，將其重新分配給一些計畫開展無線業務的小公司。
美國
   
有無執照並不重要。美國的做法十分獨特。 當世界其他地方都把目光放在3.5GHz頻段上的時候， 美國的法規卻將這些頻段從議事日程上刪去。 當FCC討論開放類似的3.6GHz頻段的時候， 大多數美國電信公司卻把希望寄託在2.5GHz MMDS上，2.5GHz頻段目前主要掌握在Sprint和Nextel手中，� L們還沒有商用計畫。
   
雖然一些規模較大的電信業者往往對無執照頻譜嗤之以鼻， 因為他們認為，無執照頻譜代表的是不安全和無法有效利用。 但情況開始有所轉變，許多專家預計大型的運營商也很有可能在無執照頻帶上 佈置WiMAX網路。在美國，電信業者雖然對在無執照頻譜中建設 WiMAX網路頗感興趣，但他們不得不等待經過認證的設備出現。
   
雖然專家預計用於無執照頻譜的設備可能要在明年下半年或者2006年才能面世， 但像奧維通這樣的廠商已經宣佈，一旦WiMAX論壇完成了規範的制定並開始進行 產品認證的話，他們將即時升級。
 
在需要執照的頻段上，目前WiMAX論壇主要將精力集中在兩個關鍵頻段： 2.5GHz MMDS頻段和3.5GHz。
 
在無需執照的頻段上，則考慮使用5.8GHz。
 
WiMAX是否與3G是競爭性的規格?
WiMAX組織在頻譜的進展
   
為解決頻譜資源供給和全球一致性的問題，2004年6月論壇建立了解決世界頻譜管理問題的工作小組。工作小組的目標是確保“有利於WiMAX (WiMAX friendly)”的頻譜資源供給和全球一致性，在世界範圍內統一採用完全相同的特定頻段，確保對已經頒發許可和豁免許可的頻譜的資源利用。
WiMAX頻譜建議
   
在需要執照的頻段上，目前WiMAX論壇主要將精力集中在兩個關鍵頻段：2.5GHz MMDS頻段和3.5GHz。雖然還有其他的頻段可以考慮，但論壇和大部分設備商成員已經下決心將主要精力集中在這兩個頻段上。在無需執照的頻段上，則考慮使用5.8GHz 。
   
另外還需考慮的問題–由於WiMAX的出現，對於付了大筆執照費的3G業者，可能會是一個相當敏感的問題；而對政府部門而言，如何在不刺激3G業者巧妙的訂定WiMAX頻道使用費也將會是一門藝術。
   
因此在WiMAX頻譜上我們認為可以採取較保守的態度，先師法美國方面，若有業者提出測試需求則可考慮以無需執照的頻段先供業者使用。
Wed Mar 16 00:33:17 CST 2011 Untitled Document
WiMax's Problem
 
WiMAX技術跟現今的無線ISP一樣，具有過多使用者與高延遲的問題
 
WiFi頻寬高，但缺點：低覆蓋率、擴展性有限
 
802.11n的問題：
   
802.11n 因使用公用頻段，而相同頻段的無線設備會干擾使其降低傳輸速率及距離
 
3G覆蓋區域大，但缺點：頻寬有限、成本較高
 
基地台之建設受到居民之反對
   
對電磁波之疑慮
   
對房地產價格之影響
Wed Mar 16 00:33:19 CST 2011 Untitled Document
Comparison of 802.11 and 802.16
Wed Mar 16 00:33:20 CST 2011 Untitled Document
802.16 Specification
Wed Mar 16 00:33:21 CST 2011 Untitled Document
Multi-Path Problem
   
WiMAX可以利用較新的多路徑技術→OFDM
Wed Mar 16 00:33:22 CST 2011 Untitled Document
OFDM
OFDM (Orthogonal Frequency Division Multiplexing:正交劃頻多工)
   
正交劃頻多工
 
是一種資料編碼的技術，利用在不同頻段同時傳送資料以增加傳輸速率
 
WiMAX使用OFDMA，
   
頻分複用和正交劃頻多工都可以將資訊分配到N個子載波傳輸， 但是正交頻分多工利用了頻率的正交性干擾為零的特點， 在有限的頻寬內增加了子載波的數量，大幅增加了傳輸率。
Wed Mar 16 00:33:23 CST 2011 Untitled Document
OFDM
Wed Mar 16 00:33:25 CST 2011 Untitled Document
Architecture of WiMAX networks
   
Micro-mobility solutions are considered to be effective mechanisms to implement fast and seamless handoff for intra-domain mobility.
   
A seamless handoff mechanism that combines hierarchical micro-mobility and fast handoff mechanism is presented
   
It mainly considers a large indoor environment with 802.11 access technology. It shows that it is possible to optimize the handoff performance of Mobile-IP under the combined mechanism.
   
Due to the proliferation of cellular networks and wireless LANs, it is well recognized the demand of co-existence of multiple wireless access technologies.
   
The notion of vertical handoff was created for connection among those technologies.
   
A metropolitan network consists of multiple technologies where various vertical handoff mechanisms are an integral part of such heterogeneous networks.
Wed Mar 16 00:33:25 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:26 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:27 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:27 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:28 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:29 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:30 CST 2011 Untitled Document
How WiMAX Work?
Wed Mar 16 00:33:30 CST 2011 Untitled Document
Vertical Handoff
Wed Mar 16 00:33:31 CST 2011 Untitled Document
Hierarchical micro-mobility
   
A metropolitan area network is intended to cover an area of 30 miles in radius.
   
It will also accommodate various wireless technologies for accessing to the internet.
   
The complexity of the network calls for a hierarchical mobility management scheme.
   
Two kinds of mobility can be defined according to the mobile user’s movement pattern.
   
In case the mobile user move between Base Stations between different domains, a mobility scheme based on Mobile-IP is utilized.
   
It provides a global mobility solution with full flexibility. There have been a lot of proposals to reduce the handoff latency of mobile-IP.
Hierarchical micro-mobility
Wed Mar 16 00:33:33 CST 2011 Untitled Document
Hierarchical micro-mobility
   
A metropolitan area network is intended to cover an area of 30 miles in radius.
   
It will also accommodate various wireless technologies for accessing to the internet.
   
The complexity of the network calls for a hierarchical mobility management scheme.
   
Two kinds of mobility can be defined according to the mobile user’s movement pattern.
   
In case the mobile user move between Base Stations between different domains, a mobility scheme based on Mobile-IP is utilized.
   
It provides a global mobility solution with full flexibility. There have been a lot of proposals to reduce the handoff latency of mobile-IP.
Hierarchical micro-mobility
Wed Mar 16 00:33:33 CST 2011 Untitled Document
Fast handoff
 
The hierarchical micro-mobility reduces the home network registration time.
 
It is observed that it still takes 300 to 400 milliseconds of delay time during handoff.
 
The fast handoff scheme intends to reduce the handoff delay by minimize the address resolution delay time.
 
The prototype mobility system - Software modules
 
It follows the Hierarchical Mobile-IP designs to include the Mobility Anchor Point (MAP) node as the separation between macro and micro mobility.
 
It can be collocated as the Base Station of the network. It can be at any level of the network if the Base Stations are arranged in a hierarchy.
Wed Mar 16 00:33:34 CST 2011 Untitled Document
Prototype - Handoff Procedure
The prototype mobility system - Handoff Procedure
Wed Mar 16 00:33:35 CST 2011 Untitled Document
Prototype - Software modules
The prototype mobility system - Software modules
 
There are six major components in the mobility manager: A Foreign agent module that hosts the MAP and holds the care-of-addresses
 
A Tunneling module that capsulate and de-capsulate the TCP messages
 
A Link Monitor module that detects signal strengths and decide on which target BS to switch to
 
A QOS module that governs the quality of the channels
 
A Security module to detect intruders and encrypt messages over the link
 
A Billing module that does customer accounting
 
The prototype mobility system - Metropolitan medical network
 
For a trial, we are implementing the Metropolitan Medical Network (MMN) based on WiMAX.
 
It is a network between health partners, hospitals, clinical laboratories and medical researchers.
 
Its primary goal is to provide real time sharing of clinical and laboratory data amongst medical hospitals and other health entities.
 
The network will be connected to the Indiana Network for Patient Care (INPC), which is one of the few operational community-wide public health reporting systems in the U.S.
 
The system currently includes data from 11 hospitals in five health systems.
Wed Mar 16 00:33:36 CST 2011 Untitled Document
Images
Wed Mar 16 00:33:36 CST 2011 Untitled Document
WiMAX News
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大眾擬引進外資 爭取WiMAX執照 Wed Mar 16 00:33:38 CST 2011 Untitled Document
WiMAX Versions
Wed Mar 16 00:33:39 CST 2011