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IEEE 802.22: An Introduction to the First Wireless Standard based on Cognitive Radios. Carlos Cordeiro , Kiran Challapali , and Dagnachew Birru Philips Research North America/Wireless Communication and Networking Dept., Briarcliff Manor, USA

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Ieee 802 22 an introduction to the first wireless standard based on cognitive radios

IEEE 802.22: An Introduction to the FirstWireless Standard based on Cognitive Radios

Carlos Cordeiro, KiranChallapali, and DagnachewBirru

Philips Research North America/Wireless Communication and Networking Dept., Briarcliff Manor, USA

Email: {Carlos.Cordeiro, Kiran.Challapali, Dagnachew.Birru}@philips.com

Sai Shankar N

Qualcomm Inc./Standards Engineering Dept., San Diego, USA

Email: [email protected]

指導教授:郭文興

學生: 林祺富


Abstract
Abstract

  • 再2004年10月全世界第一個以CR為基礎的無線空中介面802.22工作組成立了.他的主要發展任務是無線區域網路(WRAN)的PHY和MAC用來分享那些授權者的頻譜並且是在不會影響到原來使用者的權益.本篇只要是在說802.22他的構造,需求,應用和合併的定義.


大綱

  • Abstract

  • Introduction

  • Relatedwork

    A. Applications and Markets

    B. Regulatory Framework

  • The Ieee802.22preliminaries

    A. Topology, Entities and Relationships

    B. Service Capacity

    C. Service Coverage

  • Theieee802.22system

    A. Topology, Entities and Relationships

    B. Service Capacity

    C. Service Coverage


大綱

  • The802.22airinterface

    A. The PHY

    B. The MAC

    B.1 Superframe and Frame Structure

    B.2 Network Entry and Initialization

    B.3 Measurements and Spectrum Management

    B.4 Quiet Periods for Incumbent Sensing

  • Coexistenceinieee802.22

    A. Antennas

    B. Coexistence with TV and Wireless Microphones

    B.1 Sensing Thresholds

    B.2 Calculation of the Keep-Out Region

    B.3 DFS Timing Requirements

    B.4 Wireless Microphone Detection

    B.5 Spectrum Usage Table

    B.6 Out-of-Band Emission Mask

    C. Coexistence with PLMRS/CMRS

    D. Self-Coexistence


大綱

  • CONCLUSIONS

  • REFERENCES


Introduction
Introduction

  • 由於現在無線電被廣泛的使用,使得如何充分的使用頻譜變的格外的重要.感知無線電是目前最有效率利用頻譜的方法.他能感知周圍的環境,主動學習.及時改變調整內部系統的狀態,來適應外部的環境且不影響其他授權的用戶.


Related work
Relatedwork

  • 802.22和802.16之間的不同就是802.22主要是用在偏遠的地區他所涵蓋的範圍比802.16大的多.802.16也沒有對於授權者的保護的技術.


Ieee 802 22 preliminaries
Ieee802.22preliminaries

  • 市場運用:因為農村和偏遠地區地區涵蓋太大且服務困難,所以才需要WRAN.FCC之所以選擇電視頻段是因為該頻段擁有適合偏遠地區傳遞的特性,且用於802.22的設備不需要牌照,可以進一步降低成本.可是這不代表802.22只能用在農村和偏遠地區.還有許多其他地方可利用WRAN.例如—家庭用戶,多聚居單元,小商業用戶和校園.


Ieee 802 22 preliminaries1
Ieee802.22preliminaries

  • Regulatory Framework:在美國無線電主要目標是使用(VHF/UHF)的電視廣播頻段(從2到69).一般來說一個頻道佔用6MHZ,這樣開放的頻譜有3個 (54~72MHZ)(76~88MHZ)(740~806MHZ)FCC也允許無線麥克風在空閑的電視頻段進行通訊.只要不會相互影響就可以.


The ieee 802 22 system
THE IEEE 802.22 SYSTEM

  • 由於電視頻段並沒有全國統一,所以802.22所推出的標準也必須要適用於各種國家的電視通道.如 6MHZ,7MHZ,8MHZ


The ieee 802 22 system1
THE IEEE 802.22 SYSTEM

  • 拓墣的實體和關聯:

  • 802.22是單點對多點無線傳輸系統P-MP

  • 他透過BS來管理她自己的CELL和有關聯的CPE

  • BS會管理在CELL內的媒體存取,以及向下傳送訊息給cpe而CPE會向上回覆BS訊息

  • Bs會管理distributed sensing,而CPE會在不同的電視頻道去執行分散式的測量.


802 22wran
802.22WRAN的結構圖


The ieee 802 22 system2
THE IEEE 802.22 SYSTEM

  • 服務的容量:

  • 每個CPE最低下載速度為1.5 Mb/s上傳速度為384 kb/s

  • 系統規定了從0.5 bit/(sec/Hz)~5 bit/(sec/Hz)的頻譜利用率,假設平均3bit/sec/Hz將會符合在一個6MHz電視頻道內的所有的PHY18mbps的資料傳輸率


The ieee 802 22 system3
THE IEEE 802.22 SYSTEM

  • 服務的範圍:

  • 802.22WRAN的特色就在他的範圍最高可以達到100公里前提是不考慮功率的問題.

  • 現有的IEEE802標準最高只有33公里4w CPE EIRP(Effective Isotropic Radiated Power)



The ieee 802 22 air interface
THE IEEE 802.22 AIR INTERFACE

  • PHY:

  • 802.22實體層在調變和編碼方面具有高度的擴展性

  • OFDMA可以有效的分配子載波來達到CPE的需求

  • 802.22要只使用一個頻道來達到30KM和19MBPS是困難的,所以要透過頻道的融合來應加頻寬

  • 融合多個通道是理想的情況,可是主要的問題是在於沒有那麼多通道可以使用.

  • 為了避免鄰近高功率TV所產生的干擾,在所需調整的頻道兩旁必須有空的頻道.所以至少要有3個頻道




The ieee 802 22 air interface3
THE IEEE 802.22 AIR INTERFACE

  • MAC 層:

  • 為了要能夠及時的對外面環境做出回應,802.22的MAC層必需具有高度的動態性能.

  • 頻譜的分布認知和動態管理這些功能是傳統的802.22所沒有具備的功能


The ieee 802 22 air interface4
THE IEEE 802.22 AIR INTERFACE

  • BS會傳送特定的preamble及SCH透過3個鄰近的TV通道用來達到通訊的保護需求,CPE可以同步調整通道並且接收SCH,在超級訊框期間,可以使用multiple channels來傳送較多的MACFRAME,因此能提供更好的系統容量、範圍、多路徑分集及資料傳輸速率



The ieee 802 22 air interface6
THE IEEE 802.22 AIR INTERFACE

  • MACFRAME的訊框結構如下圖,包括兩個部分: (downstream, DS) 及 (upstream, US) ,這兩個部分邊界是可掉換的,所以可以很容易控制上傳/下載的容量,DS是由DS PHY PDU組成與共存目的的競爭間隔,US組成則是透過初始化的競爭間隔排程,



The ieee 802 22 air interface8
THE IEEE 802.22 AIR INTERFACE

  • Network Entry and Initialization:

  • 在WRAN中802.22中的CPE啟動時,首先必須先建立一個電視頻道的頻譜佔用情況.再把這個訊息傳回去給BS.

  • 在WRAN中802.22沒有預先先偵測頻道.可是他會進行頻道的合併,來提高性能.


The ieee 802 22 air interface9
THE IEEE 802.22 AIR INTERFACE

  • 頻譜的測量和管理:

  • 為了使802.22系統不會對使用者造成干擾,BS要引導CPE在頻道內或是頻道外進行週期性的感知測量

  • In-band必須停止一切的數據的傳送,因為它用的頻道是BS和CPE傳遞訊息的頻道

  • out-of-band則是對於其他的頻道

  • BS在偵測頻譜的使用情況時,如果又遇到了In-band會導致他在感知的時間拉長產生干擾.可是重複的感知活動也不需要每個CPE來進行

  • 802.22 也綜何管理了頻譜的功能,如切換頻道,連結頻道傳輸,終止頻道傳輸.用來保障使用者的權益


The ieee 802 22 air interface10
THE IEEE 802.22 AIR INTERFACE

  • Quiet Periods for Incumbent Sensing:

  • MAC層的穩定周期結構是由Fast Sensing和Fine Sensing 所組成的

  • Fast Sensing:包括一個或多個Fast Sensing來進行,這個階段用快速偵查演算法來進行,執行非常快速且有很高的效率.每個頻道1MS是標準.

  • Fine Sensing:他是出現在Fast Sensing後面,做出更精細的偵測.如果Fast Sensing偵測後發現受干擾的頻道能量低於門檻值, Fine Sensing就不會被執行



Vi coexistence in ieee 802 22
VI. COEXISTENCE IN IEEE 802.22

  • 天線:

  • 802.22中每個CPE都需要兩個獨立的天線. directional和omni-directional

  • directional就是工作天線,主要是用於CPE和BS之間的通信,因為它的方向是固定的,所以能量較不易散失也可以降低干擾.

  • omni-directional主要是用於感知和測量.它可以尋找CPE附近所有的使用者用戶訊號,而不是單方向的尋找,所以可以有效的避免衝突.


Coexistence in ieee 802 22
COEXISTENCE IN IEEE 802.22

  • 電視和無線麥克風的共存:

    Sensing Thresholds:BS和CPE利用omni-directional來偵測使用者的門檻值.如果使用者高於門檻值,就會清出一個空的頻道出來.

    (DTV): -116 dBm 在6MHZ頻道

    Analog TV:-94dBM在NTSC中

    Wireless microphones:-107dBM在200KHZ頻道



Coexistence in ieee 802 222
COEXISTENCE IN IEEE 802.22

  • 電視和無線麥克風的共存:

    Wireless Microphone Detection:不同於電視訊號的傳送,因為無線麥克風的功率較低頻寬較小,所以要偵測他是困難的.所以偵測和信標是兩個不能排除的選項.


Coexistence in ieee 802 223
COEXISTENCE IN IEEE 802.22

  • 電視和無線麥克風的共存:

    Spectrum Usage Table:802.22會要求BS建立一個表格,內容可以將頻道分為被佔用,可以用的和禁止使用3種.以方便802.22的感知來控制.



Coexistence in ieee 802 225
COEXISTENCE IN IEEE 802.22

  • Self-Coexistence:

    Self-Coexistence的問題就在於會產生self-interference會使的Self-Coexistence變成毫無價值.

  • 下圖X軸是numberofnetwork隨機挑選放入一個正方形的區域(50*50100*100150*150)Y軸是converge time.



Conclusions
CONCLUSIONS

  • 802.22是全世界第一個air interface和以CR為基礎的協定且操作於電視頻寬.透過頻譜的感知,使用者權益的維護,避免干擾和頻譜的管理等技術來達到有效的合併.

  • 本文提供了一個詳細的802.22WRAN的介紹.包括他的PHY和MAC的起始規格和共存的技術.


References
REFERENCES

  • [1] M. Calabrese and J. Snider, “Up in the Air,” The AtlanticMonthly, New America Foundation, September 2003.

  • [2] Federal Communications Commission (FCC), “SpectrumPolicy Task Force,” ET Docket no. 02-135, November 15,2002.

  • [3] P. Kolodzy, “Spectrum Policy Task Force: Findings andRecommendations,” in International Symposium onAdvanced Radio Technologies (ISART), March 2003.

  • [4] M. McHenry, “Report on Spectrum OccupancyMeasurements,” Shared SpectrumCompany,http://www.sharedspectrum.com/?section=nsf_summary.

  • [5] J. Mitola et al., “Cognitive Radios: Making SoftwareRadios more Personal,” IEEE Personal Communications,vol. 6, no. 4, August 1999.

  • [6] J. Mitola, “Cognitive radio: An integrated agentarchitecture for software defined radio,” PhD Dissertation,Royal Inst. Technol. (KTH), Stockholm, Sweden, 2000.


References1
REFERENCES

  • [7] S. Haykin, “Cognitive Radio: Brain-Empowered WirelessCommunications,” in IEEE JSAC, vol. 23, no. 2, February2005.

  • [8] DARPA ATO, Next Generation (XG) Program,http://www.darpa.mil/ato/programs/xg/.

  • [9] Federal Communications Commission (FCC), “Notice ofProposed Rule Making,” ET Docket no. 04-113, May 25,2004.

  • [10] IEEE 802.22 Working Group on Wireless Regional AreaNetworks, http://www.ieee802.org/22/.

  • [11] ITU’s New Broadband Statistics,http://www.itu.int/osg/spu/newslog/ITUs+New+Broadband+Statistics+For+1+January+2005.aspx, January 1, 2005.

  • [12] Federal Communications Commission (FCC), “Report andOrder AND Memorandum Opinion and Order,” ET Docketno. 05-56, March 16, 2005.

  • [13] Business Week, “Commentary: Behind in Broadband,”BusinessWeek Online Magazine, September 6, 2004.


References2
REFERENCES

  • [14] Federal Communications Commission (FCC), “Report andOrder,” ET Docket no. 05-57, March 11, 2005.

  • [15] K. Challapali, D. Birru, and S. Mangold, “Spectrum AgileRadio for Broadband Applications,” EE Times In-Focus,August 23, 2004.

  • [16] IEEE 802.16 Working Group on Broadband WirelessAccess, http://www.ieee802.org/16/.

  • [17] K. Challapali, S. Mangold, and Z. Zhong, “Spectrum AgileRadio: Detecting Spectrum Opportunities,” in ISART,Boulder, CO, March 2004.

  • [18] S. Mangold, Z. Zhong, K. Challapali, and C-T. Chou,“Spectrum Agile Radio: Radio Resource Measurements forOpportunistic Spectrum Usage,” in IEEE Globecom, 2004.

  • [19] K. Challapali, “Spectrum Agile Radios: Real-timeMeasurements,” in Cognitive Radio Conference,Washington DC, October 2004.

  • [20] A. Sahai, N. Hoven, and R. Tandra, “Some fundamentallimits on cognitive radio,” Allerton Conference onCommunication, Control, and Computing, October 2004.


References3
REFERENCES

  • [21] D. Agrawal and Q-A. Zeng, Introduction to Wireless andMobile Systems, Brooks/Cole Publishing, 432 pages, ISBN0534-40851-6, August 2002.

  • [22] H. Gossain, C. Cordeiro, T. Joshi, and D. Agrawal, “Cross-Layer Directional Antenna MAC and Routing Protocols forWireless Ad Hoc Networks,” in Wiley WirelessCommunications and Mobile Computing (WCMC) Journal,Special Issue on Ad Hoc Wireless Networks, to Appear.

  • [23] Federal Communications Commission (FCC), “Revision ofParts 2 and 15 of the Commissions Rules to PermitUnlicensed National Information Infrastructure (U-NII)Devices in the 5GHz Band,” ET Docket no. 03-122,November 18, 2003.

  • [24] G. Chouinard, “WRAN Reference Model,” IEEE 802.22,

    http://www.ieee802.org/22/, May 2005.


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