VISHNU

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• VISHNU
• 
  VASANT
• 
  PAVAN
• 
  ABHILASH

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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
• References

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Introduction

• Broadband access - In your home, you have either
  a DSL or cable modem At the office, your company
  may be using a T1 or T3 line.
• WiFi access - In your home, you may have set up a
  WiFi router that lets you surf the Web while you
  lounge with your laptop on the road, you can find
  WiFi hot spots in restaurants, hotels, coffee
  shops and libraries.
• Dial-up access - If you are still using dial-up,
  chances are that either broadband access is not
  available, or you think that broadband access is
  too expensive

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Contd..

• The main problems with broadband access are that
  it is pretty expensive and it doesn't reach all
  areas.
• The main problem with WiFi access is that hot
  spots are very small, so coverage is sparse.
  
• There is a need for a system which provides high
  speed of Broadband and is wireless instead of
  wired.
• WiMAX(Worldwide Interoperability Microwave
  Access) provides these features .Its also known
  as IEEE 802.16

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What is WiMAX?

• WiMAX (Worldwide Interoperability for microwave
  access)
• A technology based on an evolving standard for
  point-to-multi point wireless networking
• The commercialization of IEEE 802.16 standard
• Solution for Wireless Metropolitan Area Network
• BWA (Broadband Wireless Access) Solution
• Comply with European BWA standard
• European Telecommunications Standards
  Institutes's High-performance radio metropolitan
  area network (HiperMAN)

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Wireless MAN (Metropolitan Area Network)
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Contd..

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

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Operation of WiMAX

• WiMAX consists of two 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

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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 (similar
  to 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

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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

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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

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Architecture

• P2MP(Point to Multi point)
• Wireless MAN
• BS connected to Public Networks
• BS serves Subscriber Stations(SS)
• Provides SS with first mile access to Public
  Networks
• Mesh Architecture
• Optional architecture for WiMAX

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P2MP Architecture
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WiMAX Mesh Architecture
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WiMAX FUNCTIONALITY
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WiMAX Protocol

• Covers MAC layer and PHY layer
• PHY layer
• Transmission Convergence sublayer
• MAC layer

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Reference Model
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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.

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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

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Adaptive PHY
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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)

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FDD Frame bursting
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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

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Time Division Duplexing
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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

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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

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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

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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).

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MAC PDU
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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

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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

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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

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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

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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
  

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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

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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.

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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)
• 
  

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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.

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WiMAX Features

• Scalability
• Quality of service
• Range
• Coverage

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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.
• 
  
  

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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.

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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.

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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.

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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.

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Coverage

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

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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.

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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.

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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.

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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.

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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.

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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
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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.

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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).

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Benefits of WiMAX

• Speed
• Faster than broadband service
• Wireless
• Not having to lay cables reduces cost
• Easier to extend to suburban and rural areas
• Broad coverage
• Much wider coverage than WiFi hotspots

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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

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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
• Rapidly declining fixed broadband prices
• No more DSL installation fees from incumbent

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WiFi Vs WiMAX

• Scalability
• Relative Performance
• Quality of Service
• Range
• Coverage
• Security

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Scalability
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Relative Performance
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Quality Of Service (QoS)
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Range
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Coverage
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Security
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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)

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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.

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WiMAX Technology
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WiMAX Forum

• Worldwide Interoperability for Microwave Access
• WiMAX was Founded in April 01
• No Profit organization comprised of wireless
  access system manufacturers, component
  suppliers, software developers and carriers
• A wireless industry consortium that supports and
  promotes WiMAXs commercial usage
• Members include Intel, ATT, Siemens Mobile,
  British Telecommunications, etc..
• Comply with the WiMAX standard and focus on the
  interoperability

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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

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References

• http//www.ceenet.org/workshops/lectures2004/Richa
  rd_Perlman/additional_materials_(wimax)/
• www.ewh.ieee.org/r4/chicago/Yu-WiMAX.pdf
• www.WIMAXFORUM.org
• http//computer.howstuffworks.com/wimax.htm
• http//standards.ieee.org/catalog/olis/lanman.html
  
• http//netgroup.polito.it/Corsi/ISRG/Lucidi/Nicole
  tti_WiMAX.pdf
• http//www.gartner.com/teleconferences/attributes/
  attr_133634_115.pdf

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Questions

• What are different kinds of service WIMAX offers
  and what is difference between
  them?
• How is interoperability achieved in
  WIMAX?
• How is QOS implemented in WIMAX?
  
• What is difference between P2MP and Mesh
  architectures?
  
  
• List out three differences between WIMAX and WIFI?

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• QUESTIONS ?

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• THANK YOU!