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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Simple DAA Support ] Date Submitted: [ 18 January, 2006 ] Sources: [ Joe Decuir ] Company [ MCCI ] Address [ 18814 SE 42 nd St, Issaquah, WA 98027 ]

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: [Simple DAA Support]

Date Submitted: [18 January, 2006]


[Joe Decuir] Company [MCCI]

Address [18814 SE 42nd St, Issaquah, WA 98027]

Voice:[ +1 425 603 1188], FAX: [+1 425 603 0279], E-Mail:[]

Re: [Simple DAA Support]

Abstract: [Simple additions to draft 802.15.4a to support DAA, modeled on IEEE 802.11h]

Purpose: [Help accommodate anticipated world wide regulations and ballot comments]

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.


introduction scope
Introduction & Scope
  • TG4a is resolving ballots on the first draft of IEEE 802.15.4a (LB33).
  • Some of those ballots call attention to proposed regulatory restrictions that require mitigation on the UWB PHY.
  • There are two kinds of mitigation:
    • Low Duty Cycle
    • Detect And Avoid (DAA)
  • This contribution is focused on a very simple implementation of DAA with the TG4a PHY.


goals of this presentation
Goals of this presentation
  • Propose modifications to draft 802.15.4a so that it is possible for a system of compliant devices (piconet controller and simple devices) to implement DAA mitigation where it is required.
  • By doing so increase the chances that this standard can achieve acceptance by international regulators and by 802.15 voters.


detect avoid overview
Detect & Avoid Overview
  • Three parts:
    • Detect signals of interest
    • Decide what signals to Avoid
    • Implement Avoidance
  • In this proposal:
    • Devices should help detection
    • Piconet controllers make decisions
    • Piconet controllers instruct devices on channel usage and avoidance


802 15 4a daa would be simple
802.15.4a DAA would be simple
  • The UWB PHY has very simple structure:
    • Three 494 MHz channels in 3211 - 4693 MHz
    • Eight 507 MHz channels in 6084 - 10394 MHz
    • Four superset channels
  • Detection and Avoidance is in units of those channels:
    • Use the existing 500MHz granularity, not 4MHz
    • We don’t have the cost or flexibility of an OFDM radio with FFT and IFFT built in
    • We do need whatever flexibility the band plan has


detection support
Detection Support
  • Existing model: IEEE 802.11h provides an extension of 802.11a for detecting and avoiding signals in 5 – 6 GHz.
  • From 802.11h, use the concept of an STA asking another STA to make signal measurements and report results.
  • Assumptions:
    • 802.15.4a radios can only detect signals with the granularity of their UWB channels
    • 802.15.4a radios can recognize themselves


cooperative detection in 802 15 4a
Cooperative Detection in 802.15.4a
  • Define two new MAC frames, modeled on those in IEEE 802.11h:
    • Basic request (
    • Basic report (
  • Any device should support these frames if the system needs to support DAA
  • DAA support is subject to national and regional regulations; it is not a requirement of the standard.


suggested new mac frame details
Suggested New MAC frame details
  • Basic Request:
    • 1 octet channel # (Table 1b/draft 802.15.4a)
    • 1 octet measurement time (Table 53/802.15.4)
  • Basic Report:
    • 1 octet channel # (Table 1b)
    • 1 octet measurement time (Table 53)
    • 1 octet energy value (6.7.7/802.15.4)
    • 1 octet bit map of detected type:
      • 802.15.4a UWB PHY signal (e.g. preamble)
      • 802.15.4 MAC frame
      • Undetermined energy source
      • Undetermined UWB energy source (optional if possible)


daa data collection methods
DAA Data Collection Methods
  • This is difficult, because in principle victim receivers don’t transmit ‘I am a victim receiver’ messages. It helps if it transmits on the same channel that it receives on.
  • Detectors can listen for:
    • A local transmitter (easy to detect IFF it is on when you listen)
    • A remote transmitter (fainter signals are harder to detect, but false detection is a problem)
  • DAA performance standards are being developed in ETSI and in Japan
    • The work might complete by summer 2006


daa decision making
DAA Decision Making
  • The definition of DAA decision logic is beyond the scope of the 802.15.4a PHY & MAC
    • The same is true for turning ranging data into location information, draft Annex D.
  • The logical place to implement DAA logic is in the piconet controller.
  • The standard should have information on example implementation (similar to material in section 10.3 and 11.6.6 of 802.11h)
  • That example implementation should be referenced to a public DAA Performance Standard if available
  • That logic might decide that reduced duty cycle would be appropriate mitigation in some conditions.


avoidance implementation
Avoidance Implementation
  • Avoidance is simple: specify which channel to use, implicitly which to avoid.
    • We don’t require an IFFT or notch filters.
    • We would need more than one channel to choose from.
  • The piconet controller defined in the draft 802.15.4a already specifies the particular channel to use.
    • Nothing new needs to be defined


operating issues
Operating Issues
  • Applications for high rate UWB PAN, like ECMA-368, may be high duty cycle, so making time and frequency space to listen often enough is tricky.
  • Luckily, 802.15.4a systems are likely to have relatively low duty cycles, making it feasible to listen more often.
    • But: listening for signals costs power!
    • If the system duty cycles are low enough, DAA might not be necessary.


  • Detect & Avoid mitigation is tricky but possible for a system of 802.15.4a compliant devices.
  • Supporting that benefits from the addition of two MAC frames, modeled on IEEE 802.11h.
  • The draft standard should have an informative Annex that illustrates how to use these features.
    • Suggested scenario: CEPT rules; ETSI compliance standard
  • TG4a should decide whether to use this approach.
    • If so, draft text is needed before the next ballot version.
  • Including an optional detection bit for other UWB may help co-existence, for market acceptance and voter acceptance.
    • However, the 802.15.4a UWB PHY may be too simple to support distinguishing UWB from narrowband signals.


  • Andreas Molisch first mentioned the idea of using the simpler devices to be remote sensors for signals.
  • Colin Lanzl pointed out that there was already a model for this in IEEE 802.11h (which he participated in).
  • Pat Kinney pointed out that 802.15.4 already contained MLME-SCAN primitives.