Ultra Wide Bandwidth (UWB) MAC and Networking

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Ultra Wide Bandwidth (UWB) MAC and Networking

• Future Networking Research Topic
• Ke Liu
• Dec. 18, 2006

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Outlines

• The Background
• The Architecture
• Introduction to the UWB MAC protocol
• Brief introduction to UWB WiNet

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Why UWB?

• Wireless Connectivity for Digital Home

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WiMedia Participants
180 companies (PC, CE, Cellular Players)
Convergence layer for multiple protocols
WiMedia Endorses MBOA PHY May 04
UWB PHY and MAC standardization
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WiMedia UWB MAC protocol

• TDMA based
• Contention based (IEEE 802.11)
• QoS Supported (IEEE 802.11e based)
• Although IEEE 802.15.3 was being standardized, it
  ceased this.

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Basic Communication Model

• Superframe the basic timing structure for fame
  exchange
• One Superframe is composed of 256 media access
  slots (MASs)
• Each Superframe starts with a Beacon Period (BP),
  decided by the number of devices involved
• The start of BP (or Superframe) is called BPST
  (BP start time), all devices need to synchronize
  BPST with each other

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Superframe Structure

• In BP, each MAS consists of 3 Beacon Slots
• 1 Superframe 65,536 µs 256 MASs
• 1 MAS 256 µs 3 Beacon Slots
• 1 Beacon slots 85 µs

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Communication Negotiation

• The maximum size of BP consists of 96 Beacon
  slots
• Up to 94 Devices are allowed in Some Range
• Each involved device occupies one Beacon slot to
  negotiate with other devices
• Except the first 2 beacon slots can be occupied
  by some device

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Communication Negotiation (cont)

• A device starts up with scanning all channels
  (128 candidates)
• On receiving a beacon in some channel, the device
  would select it
• After scanning several (typically 3) superframes,
  it would synchronize its BPST to the hearing
  ones.
• If no beacon received on any channel, it would
  start a BP with a BPST decided by itself

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Communication Negotiation (cont)

• If a beacon slot is unoccupied, the device would
  occupy it to send its own beacon
• If no beacon slot is available, it would send its
  beacon in one of the first 2 beacon slots (signal
  slots), and the one after the last occupied
  beacon slot
• Other devices hear this signal slot beacon, would
  extend their BP length by a pre-set value
  (typically 3-6).

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Communication Negotiation (cont)

• For a given device, an unoccupied beacon slot
  means
• Beacon received through the beacon slot
• Or, beacon received by some neighbor
• All the information of devices need to be
  exchange through Information Elements (IEs) along
  with beacon exchanging

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Important IEs Examples

• BPOIE Beacon Period Occupancy IE
• BP Switch IE synchronizing BPSTs of neighbors
• Identification IE addressing devices
• DRP IE distributed reservation protocol IE
• DRP Availability IE the DRP communication MAP
• PCA IE prioritized contention access IE

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Data Communication DRP and PCA

• Distributed Reservation Protocol (DRP)
• Device reserves several MASs for sending data
  through DRP IE
• If no conflict, other devices would reply
  through DRP availability IE with reserved MASs
  updated,
• Device sends data at least one superframe later
  after it sends request
• Prioritized Contention Access (PCA)
• For any MASs un-reserved, any device can obtain
  the sending token through a mechanism as IEEE
  802.11e

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Data Communication Acknowledges

• 3 Acknowledge methods
• No-Ack no acknowledge required
• Imm-Ack acknowledge is required for each packet
  received
• B-Ack block acknowledge, one acknowledge is
  required for each block (block size varies)
• The acknowledge requirement is set through packet
  header

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DRP Throughput simulation demo
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DRP Throughput simulation demo (cont)
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Primary References Web Links

• WiMedia Alliance http//www.wimedia.org