tvws:connecting unconnected

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  • TVWS: Connecting unconnected

    Gururaj Padaki | Jayaram Shanbhag

    Saankhya Labs Pvt Ltd.

  • Agenda

    Need for Rural connectivity

    Rural Broadband: Available solutions and Issues

    Requirement for Rural Broadband

    TVWS for Rural Broadband

    Brief overview to 802.22 standard

    Q&A

  • Need for connectivity

    We are more dependent on the Internet for communication, information, health services, education, disaster management and business relations

    Internet has to be seen Basic Human Right in days to come

    out of 7.2 billion world population only 3.3 billion populations is connected through internet

    Out of 3.9 billion unconnected internet population 800million population is from INDIA ideal case for make in INDIA and for INDIA

    10% increase in internet penetration can boost GDP by 1.4%: ITU

  • Need for Rural connectivity

    Connectivity is a MUST for rural area to manage limited resources and utilize them in a efficient way like power, irrigation etc.

    Improves education and health services in rural area

    E-commerce platform to connect end buyers to farmer eliminating middle men

  • Rural Broadband : Available solutions and Issues

    ADSL/Cable/Fiber

    Mobile telephony(2G/3G and 4G)

    Wi-Fi (IEEE 802.11a/b/g/n)

    Wi-Max (IEEE 802.16)

    Satellite

  • ADSL/Fiber/Cable

    The most common type of broadband connection worldwide.

    QoS you achieve relies heavily on how close your telephone exchange.

    As rural areas are sparsely populated, service providers are unlikely to be interested as it wouldnt be commercially viable.

    Big challenge in Operation and Maintenance of cabling.

    With cabling, need another 20years to cover remaining 3.9billion population.

  • Mobile telephony (3G and 4G)

    This is one of the fast and scalable ways to connect rural area.

    Involves costly wave spectrum

    Unfortunately 3G/4G coverage in countries like INDIA is patchy, particularly in the rural areas.

    High entry costs and poor ROIs currently doesnt suit the growing countries like INDIA.

  • Wi-Fi (IEEE 802.11a/b/g/n)

    Works with un- licensed band and cost effective CPE(Customer Premises Equipment) and AP(Access Point) for deployments.

    Well suited for coverage up to 100-200meters.

    Not suitable for sparsely populated rural area of 15-20kms.

  • Wi-Max (IEEE 802.16)

    Mobile Wi-MAX was a replacement candidate for GSM and 3G technologies.

    Wi-Max operates from 2 to 11 GHz licensed band and based on WRAN topology.

    This is good candidate for last mile rural connectivity which is limited up to 2-3Kms due to its short multipath handling capability.

  • Satellite

    Better alternative to cover bigger geography wirelessly.

    Building, launching and operating satellites is very expensive which makes service to be costly.

    High latency as signal have to travel 46000 miles from customer end to back haul gateway.

    Needs line of site link and depends on weather conditions.

  • Comparison of different options

    Standard Range (KMs)

    Entry Cost

    Frequency Band

    Deployment time

    Maintenance cost

    Network latency

    ADSL/Cable/Fiber

    1-2 High NA High High Low

    Mobile telephony

    5(typical) High Licensed Medium Medium Low

    Wi-Fi 0.1 Low Un-licensed

    Low Low Low

    Wi-Max 2-3 Medium Licensed Low Low Low

    Satellite >100 High Licensed High Low High

  • Requirement for Rural Broadband

    Entry Cost Low like Wi-Fi

    Range at least 15-20Kms

    Deployment time and Scalability like Wi-Fi

    Network Latency -

  • Characteristics of different WRAN standards

  • Rural Broadband Who Fits the Bill

    802.22b - Cognitive Wireless Regional Area Network(WRAN) Range 30Kms

    Network Topology WRAN(Fixed installation),no mobility

    Entry Cost Less, uses un-licensed TVWS Band

  • What/Where is TVWS

    TV Whitespace(TVWS) are unused gaps in TV broadcast spectrum (470-690MHz)

    Where

    TVWS Policy in place

    USA, UK, Philippines, Singapore, Korea, South Africa

    Under consideration/Trials

    India, Indonesia, Vietnam, Japan

    Malawi, Kenya, Botswana

    Brazil, Argentina, Columbia

    Kazakhstan

  • Why TVWS

    Better Coverage than Wi-Fi FSPL(dB)=20log10(d)+20log10(f)+

    92.45 FSPL free space path loss d distance in KMs f frequency in GHz

    Long range with low power Fewer towers Lower Capex Runs off solar power Lower

    Opex Ideal for low user density areas

    Better Non-Line-of-Sight (NLOS) Performance

    Picture courtesy: Carlson wireless

  • Spectrum allocation in TVWS Band

    TVWS Band allocation by taking existing licensed use Offer the promise of opportunistic access to under-utilized

    frequency bands Location-aware wireless BS/CPE devices, assisted by

    databases for band allocation

  • Overview 802.22 Focus Area Rural Wireless broadband service

    Core Technology Cognitive radio technology based un-licensed TVWS

    Band without affecting incumbents Spectrum sensing, spectrum management, intra-

    system co-existence, geo-location Mobility and Portability

    Limited mobility support with NO hand-off

    Network Topology Point to Multi Point Max EIRP 4W Cell Radius up to 100KMs (with MAC support) Incumbent Protection Sensing and Data base access

  • Overview 802.22 Protocol Reference Model

  • Overview 802.22 Frame Structure

    TDD Frame structure support

    Super Frame:160ms Frame:10ms

    Each frame consists of downlink (DL) sub-frame, uplink (UL) sub-frame, and the Co-existence Beacon Protocol (CBP) burst

    Lengths of DL and UL sub-frames can be adjusted

    Self Co-existence Window: BS commands subscribers to send out CBPs for 802.22

  • Overview 802.22 PHY Features

    PHY Transport -OFDM as transport mechanism. OFDMA is used in the UL

    Modulation-QPSK, 16-QAM and 64-QAM

    CodingConvolutional Code is Mandatory. Turbo, LDPC or Shortened Block Turbo Code are Optional but recommended.

    Pilot Pattern -Each OFDM / OFDMA symbol is divided into sub-channels of 28 sub-carriers of which 4 are pilots.

    Max Spectral Efficiency - 3.5 bits/s/Hz

    Spectral Mask As proposed by FCC

  • Overview 802.22 MAC Features

    Connection-oriented MAC, establishes connection IDs and service flows which are dynamically created

    QoS Various types of QoS services are supported (UGS,rtPS,nrtPS,BE). ARQ supported. Uni-cast, Multi-cast and broadcast services are supported.

    Dynamic and adaptive scheduling of quiet periods to allow the system to balance QoS requirements of users with the need to quiet down the network to support spectrum sensing

    Subscribers can alert the BS, the presence of incumbents in a number of ways

    BS can ask one or more subscribers to move to another channel in a number of ways using Frame Control Header (FCH)or dedicated MAC messages

  • Overview 802.22 Cognitive Features

    comprises of Spectrum Sensing Function (SSF), the Geo location (GL) function, the Spectrum Manager/Spectrum Sensing Automaton (SM/SSA) and a dedicated security sub layer 2

    Spectrum Sensing Function - observes the RF spectrum of a television channel for a set of signal types and reports the results of this observation. Present in both BS and CPE

    Spectrum Manager- Responsible for spectrum availability information, channel selection, channel management, scheduling spectrum sensing operation, access to the database, enforcing IEEE 802.22 and regulatory domain policies. Present only at BS

  • Overview 802.22 Field Deployment Scenario

    Picture courtesy: http://ecee.colorado.edu/~ecen4242/802_22/general_info.html

  • Overview 802.22 Field Deployment

    Base station Installation

    CPE Installation

  • gururaj@saankhyalabs.com jayaram@saankhyalabs.com

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