TG3 Overview of the Draft Standard

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Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
Overview of Draft Standard 802.15.3 Date
Submitted 14 November 2001 Source James P.
K. Gilb Company Mobilian Address 12707
High Bluff Dr., Suite 335, San Diego, CA,
92130 Voice1-858-436-2201, FAX
1-858-436-2301, E-Mailgilb_at_ieee.org Re
Abstract Liaison report to the 802.15 WG on
the status of the 802.11g TG. Purpose To
report the status of the 802.11g TG to the 802.15
WG.. Notice This document has been prepared to
assist the IEEE P802.15. It is offered as a
basis for discussion and is not binding on the
contributing individual(s) or organization(s).
The material in this document is subject to
change in form and content after further study.
The contributor(s) reserve(s) the right to add,
amend or withdraw material contained
herein. Release The contributor acknowledges and
accepts that this contribution becomes the
property of IEEE and may be made publicly
available by P802.15.
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Environment and Applications
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Environment

• Relatively short range
• Required coverage is gt 10 m
• Dynamic environment
• Mobile devices, enter and exit piconet often
• Low speed (lt 7 kph)
• Personal/home environment
• User controls all devices in the WPAN
• Low delay spread (lt 25 ns)

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Sample Applications

• Multimedia
• Streaming audio and video
• Interactive audio and video
• Data
• PDAs, PCs, printers
• Projectors
• Digital imaging
• Still image and video
• Camera to kiosk

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Requirements

• Range gt 10 m
• Data rate gt 20 Mb/s
• QoS capable
• Security for Ad Hoc Networks
• Quick join/unjoin
• Basic security/authentication
• Low power, cost, size, complexity
• Piconet, not network connectivity

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MAC Characteristics
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Qualities of the 802.15.3 MAC

• Coordinator (PNC) Device (DEV) topology
• PNC assigns time for connections
• Commands go to and come from the PNC.
• Communication is peer-to-peer
• Quality of Service
• TDMA architecture with guaranteed time slots
  (GTSs)
• Security and Authentication

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Basic structure is the superframe

• 3 parts to the superframe
• Beacon
• Contention Access Period (CAP)
• Contention Free Period (CFP)
• CFP has GTSs and MTSs

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Access methods

• Beacon
• TDMA, only sent by the PNC
• CAP
• CSMA/CA, types of data and commands can be
  restricted by PNC
• PNC can replace the CAP with management time
  slots (MTSs) using slotted-aloha access.
• CFP
• TDMA, assigned by the PNC
• GTSs are unidirectional

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PNC selection/handover

• Alternate coordinators (ACs) broadcast
  capabilities
• Based on criteria, best AC is chosen and
  becomes the PNC
• PNC begins to issue beacon
• PNC hands over task if more capable AC joins
  the piconet
• Exception only if security policy is verified

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Joining/transferring data

• DEV joins with association command
• PNC allows based on resources
• DEV authenticates (if required)
• DEV can either
• Send data in CAP (if allowed)
• Request GTS for specific connection
• GTSs may be either
• Stream data connection has QoS requirements
• Non-stream connection has no QoS requirements

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Types of GTS

• GTS may have different persistence
• Dynamic GTS position in superframe may change
  from superframe to superframe
• Pseudo-static GTS PNC may change position, but
  needs to communicate and confirm with both DEVs
• MTS
• Used for PNC/DEV communication
• May be used to substitute for CAP

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4 ACK policies supported

• No ACK
• Useful for streaming content
• Immediate ACK (Imm-ACK)
• ACKs immediately follow the packet
• Delayed ACK (Del-ACK)
• ACK multiple packets in one ACK command
• Implied ACK
• ACK is implied by a data frame returned in
  reverse direction with ACK policy implied-ACK

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4 Frame types

• Beacon - PNC uses to synchronize piconet
• Immediate ACK
• Commands
• Multiple commands may be in one frame
• Commands and information elements are TLV (a TLA
  for Type, Length and Value)
• Data
• May contain encryption information.

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Commands

• Commands support
• PNC selection and handover
• Association and disassociation
• Information request commands
• Repeater service
• Power management commands
• Device information
• Retransmission
• Request and modify GTS allocations

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MAC support

• Peer Discovery
• Multirate support
• Repeater service
• Dynamic channel selection
• Power management
• Transmit power control

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PHY Characteristics
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General characteristics

• 2.4 GHz band
• Unlicensed operation
• 15 MHz RF bandwidth
• 3 or 4 non-overlapping channels
• Similar to 802.11 for coexistence
• 5 data rates
• 11 Mbaud
• 11-55 Mb/s with multi-bit symbols and coding
• Use Trellis Coded Modulation (TCM) for coding

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Modulation, rates and sensitivity
TCM was originally used in phone modems, many
publications gt 20 years old.
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Receiver characteristics

• Defined in draft
• Minimum sensitivities and maximum signal
• Adjacent and alternate channel blocking
• RSSI, CCA and Link Quality Indication (LQI)
• Implementation dependent
• Intermodulation performance
• Equalization

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Transmitter specifications

• TX power
• Up to 100 mW in EC
• Up to 125 mW with FCC NPRM
• 10 mW in Japan
• Transmit power control
• If over 4 dBm, will control to less than 4 dBm
  in monotonic steps of 3 to 5 dB
• EVM spectral mask define signal quality
• Baseband TX filter undefined

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Miscellaneous PHY items

• Frequency timing derived from same clock
• Should simplify RX modem implementation
• CAZAC sequence for preamble
• Optimum for equalization, timing and frequency
  recovery 1
• Equalization or diversity supported for delay
  spread mitigation
• 1 A. Milewski, Periodic Sequences with
  Optimal Properties for Channel Estimation and
  Fast Start-Up Equalization, IBM Journal of
  Research and Development, vol. 27, no. 5, pp.
  426-431, September 1983.