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Title: Chaiyut Santananukarn


1
  • Chaiyut Santananukarn
  • Assistant Vice President
  • chaiyut_at_cattelecom.co.th

2
Contents
  • Introduction
  • What is WiMAX?
  • IEEE 802.16 Extensions
  • Architecture
  • Functionality
  • WiMAX Protocol
  • Scenario
  • Features
  • Security Issues
  • Benefits
  • WiFi vs WiMAX
  • WiMAX Applications
  • Future of WiMAX
  • Conclusion

3
Introduction
  • Broadband access - ?????????????????????????? DSL
    or cable modem ???? At the office
    ???????????????????????????????????
  • WiFi access ???????????????? set up WiFi router
    ?????????????????????????? ???????????????????
    restaurants, hotels, coffee shops and libraries.
    ?????????????????
  • Dial-up access ??????????????????????????
    dial-up, ??????????????????? broadband access
    ??????????????????????????????????????

4
Contd..
  • ???????????? broadband access ????????????????????
    ????????????????????????
  • ???????????? WiFi access ????????????????????????
    ???????
  • ??????????????????????????????????????Broadband
    ??? wireless ????? wired.
  • WiMAX(Worldwide Interoperability Microwave
    Access) provides these features .Its also known
    as IEEE 802.16

5
What is WiMAX?
  • WiMAX (Worldwide Interoperability for microwave
    access)
  • ????????????????????????????????? point-to-multi
    point wireless networking
  • The commercialization of IEEE 802.16 standard
  • Solution for Wireless Metropolitan Area Network
    (Wireless MAN )
  • BWA (Broadband Wireless Access) Solution
  • ????????????????????????? (European BWA standard)
  • European Telecommunications Standards
    Institutes's High-performance radio metropolitan
    area network (HiperMAN)

6
  • WiMAX ?????????????? ???????? IEEE ??????? 802.16
    ?????????????????????? 3 ??????????
  • 802.16 ????????? 1-3 ???? ????????????????????
    ????????? Line of Sight ??????????????????????????
    ??????????????
  • 802.16a ????????? 3 - 30 ???? ????????? Line of
    Sight
  • 802.16e ????????? 1 - 3 ???? ????????? Line of
    Sight ??????????????????????????????? 802.16 ???
    802.16a ???????? ?????????????????????????????????
    ?????????? ???????????????????????

7
WiMAX ???????????????
  • ???????????????????? IEEE 802.16 ?????
    ????????????????????? Orthogonal Frequency
    Division Multiplexing (OFDM) ?????????????????????
    ???????????????????????????????
  • ??????????????????? OFDM ?????????????????????????
    ?????????? (sub-carrier) ?????????????????????????
    ? ?????????????????????????????? (????? kHz)
    ????????????????????????????????????????????????

8
Contd..
  • Coverage range up to 50km and speeds up to
    70Mbps(shared among users).

9
Operation of WiMAX
  • WiMAX ?????????? 2 parts
  • A WiMAX tower, similar in concept to a cell-phone
    tower - A single WiMAX tower can provide coverage
    to a very large area -- as big as 3,000 square
    miles
  • A WiMAX Receiver The receiver and antenna could
    be a small box or PCMCIA card, or they could be
    built into a laptop the way WiFi access is today

10
Service Types
  • Non-Line-Of-Sight
  • A Service where a small antenna on your computer
    connects to the tower. In this mode, WiMAX uses a
    lower frequency range -- 2 GHz to 11 GHz ( ??????
    WiFi )
  • Line-Of-Sight
  • A Service where a fixed dish antenna points
    straight at the WiMAX tower from a rooftop or
    pole. Line-of-sight transmissions use higher
    frequencies, with ranges reaching a possible 66
    GHz

11
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12
??????? IEEE 802.16 ??????????????????????????????
????? non line-of-sight ?????????????
??????????????????????????????????????????????????
????? line-of-sight
13
IEEE 802.16
  • IEEE 802.16 was completed on Oct, 2004
  • Range - 30-mile (50-km) radius from base station
  • Speed - 70 megabits per second
  • Line-of-sight not needed between user and base
    station
  • Frequency bands - 2 to 11 GHz and 10 to 66 GHz
    (licensed and unlicensed bands)
  • Defines both the MAC and PHY layers and allows
    multiple PHY-layer specifications

14
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15
IEEE Extensions
  • 802.16a
  • use the licensed and license-exempt frequencies
    from 2 to 11Ghz
  • Support Mesh-Network
  • 802.16b
  • Increase spectrum to 5 and 6GHz
  • Provide QoS (for real-time voice and video
    service)
  • 802.16c
  • Represents a 10 to 66GHz system profile
  • 802.16d
  • Improvement and fixes for 802.16a
  • 802.16e
  • Addresses on Mobile
  • Enable high-speed signal handoffs necessary for
    communications with users moving at vehicular
    speeds

16
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17
Comparison Chart
Technology Standard Usage Throughput Range Frequency
Wi-Fi 802.11a WLAN Upto 54Mbps 300 feet 5Ghz
Wi-Fi 802.11b WLAN Upto11Mbps 300 feet 2.4Ghz
Wi-Fi 802.11g WLAN Upto54Mbps 300 feet 2.4Ghz
WiMAX 802.16d WMAN Upto75Mbps 4-6 Miles 11Ghz
WiMAX 802.16e Mobile WMAN Upto30Mbps 1-3 Miles 2-6Ghz
WCDMA 3G WWAN Upto2Mbps 1-5 Miles 2100Mhz
CDMA 2000 3G WWAN Upto 2.4Mbps 1-5 Miles 2100Mhz
18
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19
Architecture
  • P2MP(Point to Multi point)
  • Wireless MAN
  • BS connected to Public Networks
  • BS serves Subscriber Stations(SS)
  • Provides SS access to Public Networks
  • Mesh Architecture
  • Optional architecture for WiMAX

20
P2MP Architecture
21
WiMAX Mesh Architecture
22
WiMAX FUNCTIONALITY
23
WiMAX Protocol
  • Covers MAC layer and PHY layer
  • PHY layer
  • Transmission Convergence sublayer
  • MAC layer

24
WiMAX NETWORK
25
Mac and physical layers
26
PHY Layer
  • In the design of the PHY specification for 1066
    GHz, line-of-sight propagation was deemed a
    practical necessity.
  • Because of the point-to-multipoint architecture,
    the BS basically transmits a TDM signal, with
    individual subscriber stations allocated time
    slots serially.
  • The PHY specification defined for 1066 GHz uses
    burst single-carrier modulation with adaptive
    burst profiling in  which transmission
    parameters, including the modulation and coding
    schemes, may be adjusted individually to each
    subscriber station (SS) on a frame-by-frame
    basis. Both TDD and burst FDD variants are
    defined.
  • Channel bandwidths of 20 or 25 MHz (typical U.S.
    allocation) or 28 MHz (typical European
    allocation) are specified, along with Nyquist
    square-root raised-cosine pulse shaping with a
    roll off factor of 0.25.

27
Contd..
  • Adaptive Burst Profiles
  • On DL, multiple SS's can associate the same DL
    burst
  • On UL, SS transmits in an given time slot with a
    specific burst
  • Allows use of directional antennas
  • Improves range
  • Allows use of two different duplexing schemes
  • Frequency Division Duplexing (FDD)
  • Time Division Duplexing (TDD)
  • Support for both full and half duplex stations

28
Adaptive PHY
29
FDD (Frequency Division Duplexing)
  • In case of FDD both uplink and downlink channels
    are on separate frequencies
  • The capability of downlink to be transmitted in
    bursts simultaneously supports two different
    modulation types
  • Full Duplex SS's( which can transmit and receive
    simultaneously)
  • Half Duplex SS's( which cannot)

30
FDD Frame bursting
31
TDD (Time Division Duplexing)
  • In case of TDD both uplink and downlink
    transmissions share the same frequency but are
    separated on time
  • A TDD frame has a fixed duration and also
    consists of one uplink and one downlink frame
  • TDD framing is Adaptive

32
Time Division Duplexing
33
Data Rates
  • Data rates determined by exact modulation and
    encoding schemes
  • TDD and FDD supported in 802.16 to accommodate
    burst profiling
  • 802.16a adds OFDM and OFDMA to support NLOS
    multipath propagation

34
Medium Access Control(MAC)
  • WirelessMAN Point-to-Multipoint and optional
    mesh topology
  • Connection-Oriented
  • Connection ID(CID),Service Flows(FS)

  • MAC layer is further subdivided into three layers
  • Convergence sub-layer (CS)
  • Common part sub-layer (CPS)
  • Privacy sub-layer

35
MAC Addressing
  • SS has 48-bit 802.3 MAC address
  • BS has 48-bit base station ID
  • Not a MAC address
  • Connection ID (CID)
  • 16 bit
  • Used in MAC PDU
  • Connection Oriented Service

36
Frame Structure and PDU
  • Each MAC packet consists of the three components,
  • A MAC header, which contains frame control
    information.
  • A variable length frame body, which contains
    information specific to the frame type.
  • A frame check sequence (FCS), which contains an
    IEEE 32-bit cyclic redundancy code (CRC).

37
MAC PDU
38
MAC CS Sub Layer
  • Interoperability requires convergence sub-layer
    to be service specific
  • Separate CS layers for ATM packet protocols
  • CS Layer
  • Receives data from higher layers
  • Classifies data as ATM cell or packet
  • Forwards frames to CPS layer

39
Contd..
  • Packet Convergence Sub-Layer
  • Initial support for Ethernet, VLAN, IPv4, and
    IPv6
  • Payload header suppression
  • Full QoS support
  • ATM Convergence Sub-Layer
  • Support for VP/VC switched connections
  • Support for end-to-end signaling of dynamically
    created connections
  • ATM header suppression
  • Full QOS support

40
MAC CPS Layer
  • Performs typical MAC functions such as addressing
  • Each SS assigned 48-bit MAC address
  • Connection Identifiers used as primary address
    after initialization
  • MAC policy determined by direction of
    transmission
  • Uplink is DAMA-TDM
  • Downlink is TDM
  • Data encapsulated in a common format facilitating
    interoperability
  • Fragment or pack frames as needed
  • Changes transparent to receiver

41
MAC PDU Types
  • Data MAC PDUs
  • HT 0
  • Payloads are MAC SDUs/segments, i.e., data from
    upper layer (CS PDUs)
  • Transmitted on data connections
  • Management MAC PDUs
  • HT 0
  • Payloads are MAC management messages or IP
    packets encapsulated in MAC CS PDUs
  • Transmitted on management connections
  • BW Req. MAC PDUs
  • HT 1 and no payload, i.e., just a Header

42
MAC PDU Transmission
  • MAC PDUs are transmitted on PHY bursts
  • The PHY burst can contain multiple FEC blocks
  • Concatenation
  • Multiple MAC PDU's can be concatenated into a
    single transmission in either uplink or downlink
    direction
  • Fragmentation
  • Each MAC SDU can be divided into one or more MAC
    PDU's
  • Packing
  • Packs multiple MAC SDU's into a single MAC PDU

43
MAC Privacy Sub Layer
  • Provides secure communication
  • Data encrypted with cipher clock chaining mode of
    DES
  • Prevents theft of service
  • SSs authenticated by BS using key management
    protocol

44
Transmission Convergence Sublayer
  • This layer performs the transformation of
    variable length MAC protocol data units (PDUs)
    into the fixed length FEC blocks (plus possibly a
    shortened block at the end) of each burst.
  • The TC layer has a PDU sized to fit in the FEC
    block currently being filled. It starts with a
    pointer indicating where the next MAC PDU header
    starts within the FEC block. The TC PDU format
    allows resynchronization to the next MAC PDU in
    the event that the previous FEC block had
    irrecoverable errors.

45
WiMAX Scenario
  • Consider a scenario where a wimax-enabled
    computer is 10 miles away from the wimax base
    station.
  • A special encryption code is given to computer to
    gain access to base station.
  • The base station would beam data from the
    Internet required for computer (at speeds
    potentially higher than today's cable modems)


46
Contd..
  • The user would pay the provider monthly fee for
    using the service. The cost for this service
    could be much lower than current high-speed
    Internet-subscription fees because the provider
    never had to run cables.
  • The WiMAX protocol is designed to accommodate
    several different methods of data transmission,
    one of which is Voice Over Internet Protocol
    (VoIP).
  • If WiMAX-compatible computers become very
    common, the use of VoIP could increase
    dramatically. Almost anyone with a laptop could
    make VoIP calls.

47
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48
WiMAX Features
  • Scalability
  • Quality of service
  • Range
  • Coverage

49
Scalability
  • The 802.16 standard supports flexible radio
    frequency (RF) channel bandwidths.


  • The standard supports
    hundreds or even thousands of users within one RF
    channel.
  • As the number of subscribers grow the spectrum
    can be reallocated with process of sectoring.

50
Quality Of Service
  • Primary purpose of QoS feature is to define
    transmission ordering and scheduling on the air
    interface.
  • These features often need to work in conjunction
    with mechanisms beyond the air interface in order
    to provide end to end QoS or to police the
    behaviour or SS.
  • Standard defines several QoS related concepts.
  • - Service flow Qos scheduling.
  • - Dynamic service Establishment.
  • -Two Phase Activation Model.

51
Theory Of Operation
  • All protocol mechanisms support Qos for both
    uplink and downlink traffic through the SS and
    BS.
  • Requirements for QoS
  • - A configuration and registration function
    to pre configure SS based QoS service flows and
    traffic parameters.
  • - A signalling function for dynamically
    establishing Qos enabled service flows and
    traffic parameters.
  • - Utilization of MAC scheduling and QoS
    traffic parameters for uplink service flows.
  • - Utilization of QoS traffic parameters for
    downlink service flows.

52
Service flows
  • A service flow is a MAC transport service that
    provides unidirectional transport of packets
    either to uplink packets transmitted by the SS or
    to downlink packets transmitted by the
    BS.
  • A service flow is characterized by a set of QoS
    parameters such as latency,jitter and throughput
    assurances.
  • In order to standardize operations between SS and
    BS these attributes include details of how the SS
    requests uplink bandwidth allocations and the
    expected behaviour of the BS uplink
    scheduler.

53
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54
Range
  • Optimized for up to 50 Km.
  • Designed to handle many users spread out over
    kilometres.
  • Designed to tolerate greater multi-path delay
    spread (signal reflections) up to 10.0µ seconds.
  • PHY and MAC designed with multi-mile range in
    mind.

55
Coverage

  • Standard supports mesh network topology.
  • Optimized for outdoor NLOS performance.
  • Standard supports advanced antenna techniques.

56
Security Issues
  • Security provides subscribers with privacy across
    the fixes broadband wireless network.
  • Security is implemented by encrypting connections
    between SS and BS.
  • Protection against unauthorized access to the
    data transport services is done by enforcing
    encryption of the associated service flows
    across the network.

57
Security Architecture
  • Two component protocols
  • - An encapsulation protocol for
    encrypting packet data across fixed network.
  • - A key management protocol (PKM) providing
    the secure distribution of keying data from
    BS to SS.

58
Packet Data Encryption
  • Encryption services are defined as set of
    capabilities within the MAC security sub layer.
  • MAC Header information specific to encryption is
    allocated in the generic MAC header format.
  • Encryption is always applied to the MACPDU
    payload, generic MAC is no encrypted.
  • All MAC management messages shall be sent in
    clear to facilitate registration,ranging and
    normal operation of the MAC.

59
Key Management Protocol
  • An SS uses the PKM protocol to obtain
    authorization and traffic keying material from
    the BS.
  • PKM protocol is also used for periodic
    reauthorization and key refresh.
  • PKM uses X.509 certificates and the RSA pubic
    -key encryption algorithm to perform key
    exchanges between SS and BS.

60
Contd..
  • PKM protocol adheres to a client/server model.
  • SS acts like PKM client and requests for keying
    material and BS acts like PKM server and responds
    to the requests ensuring that individual SS
    clients receive only keying material for which
    they are authorized.
  • PKM protocol uses MAC management messaging
    PKM-RSP messages.

  • PKM protocol uses public-key cryptography to
    establish a shared secret between the SS and the
    BS.

61
Security Association
  • A security Association is the set of security
    information a BS and one or more of its clients
    SS s share in order to support secure
    communication across the IEEE std 802.16 network.

  • Three types of SA are defined
  • Primary SS establishes a primary
    security association
  • during the SS
    initialization process.
  • Static Static SA are provisioned
    within the BS.
  • Dynamic Dynamic SA are established
    and eliminated
  • on fly in response to
    the initiation and
  • termination of
    specific service flows.
  • Static and Dynamic SA can be shared by multiple
    SS.

a
62
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63
Contd..
  • Figure conceptually depicts end-to-end
    Authentication, Authorization, and Accounting
    (AAA) on 802.16 networks supporting portability
    and fully mobile operations.
  • Encryption (security association) is established
    using the PKM-EAP protocol.
  • Extensible Authentication Protocol (EAP) is
    carried over RADIUS or DIAMETER to the
    AAA back end.

64
Contd..
  • Intel recommends using an end-to-end tunnelling
    protocol such as Protected EAP (PEAP) or
    Tunnelled TLS (TTLS) to afford mutual
    authentication.
  • It also recommends 128-bit or better Transport
    Layer Security (TLS) encryption to further
    enhance end-to-end security (especially in
    situations where cryptographically weaker EAP
    methods may be deployed).

65
Benefits of WiMAX
  • Speed
  • ???????? broadband service
  • Wireless
  • ???????????????????????????? lay cables
  • ??????????????????????????????
  • Broad coverage
  • Much wider coverage than WiFi hotspots

66
Benefits for Network Service Providers
  • Allow service providers to deliver high
    throughput broadband based services like VoIP,
    high-speed Internet and Video
  • Facilitate equipment compatibility
  • Reduce the capital expenditures required for
    network expansion
  • Provide improved performance and extended range
  • Allow service providers to achieve rapid ROI and
    maximize revenues (?????? ???????????????)

67
Benefits for consumers
  • Range of technology and service level choices
    from both fixed and wireless broadband operators
    (????????????????)
  • DSL-like services at DSL prices but with
  • portability (?????????? DSL ?????????????????????
    ?)
  • Rapidly declining fixed broadband
    prices(???????????? ???????????????)
  • No more DSL installation fees from
  • incumbent (????????????????????????????)

68
WiFi Vs WiMAX
  • Scalability
  • Relative Performance
  • Quality of Service
  • Range
  • Coverage
  • Security

69
Scalability
70
Relative Performance
71
Quality Of Service (QoS)
72
Range
73
Coverage
74
Security
75
Applications
  • Fixed last-mile broadband access as a replacement
    or substitute for wired DSL, cable, or T1
    connections (?????)
  • Inexpensive backhaul for cell sites and WiFi
    hotspots
  • High speed enterprise connectivity for businesses
  • Voice Over Internet Protocol (VOIP)

76
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77
Future of WiMAX
  • WiMAX will be deployed in three phases
  • In the first phase WiMAX technology (based on
    IEEE 802.16-2004) provides fixed wireless
    connections
  • In the second phase WiMAX will be available as a
    cheap and self-installing Subscriber Terminal
    (ST), linked to PC and to antenna
  • The third phase enables portability, thus WiMAX
    (based on IEEE 802.16e) will be integrated into
    commercial laptops.

78
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79
Conclusion
  • WiMAX is poised to be the next Big Thing
  • WiMAX will connect you to the internet at faster
    speeds and from much longer ranges
  • WiMAX can handle last-mile access in remote areas
    (????????????????????)
  • Mobility can be achieved with design into
    computer chips

80
Example From Fixed to Mobile Broadband Wireless
81
WiMax Antenna
82
  • THANK YOU!
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