1. March 2004
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Synchronized Beacon Propagation for Spanning Tree Networks]
Date Submitted: [18 March 2004]
Source: [Phil Beecher] Company [CompXs Ltd]
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Abstract: [The current specification does not provide support for synchronizing beacons in beacon-enabled spanning tree networks. This document points out the limitations and suggests possible solutions.]
Purpose: [This document is submitted for consideration for revisions to the specification.]
Notice: This document has been prepared to assist the IEEE P 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 P
Phil Beecher, CompXs Ltd

2. Synchronized Beacon Propagation in 802.15.4
March 2004
Synchronized Beacon Propagation in
Phil Beecher, CompXs Ltd
Phil Beecher, CompXs Ltd

3. March 2004
Problem: Superframes are not synchronized in a beacon-enabled spanning tree PAN
The network layer of a secondary coordinator has no way to control the timing of its beacons relative to the PAN coordinator.
This may cause the following effects:
Clock drift will lead to collision between beacons.
Possible violation of CFP of the PAN coordinator
Phil Beecher, CompXs Ltd

4. March 2004
Solutions
Explicitly prohibit Spanning tree networks in beacon-enabled PANs
Provide method to allow synchronization.
Phil Beecher, CompXs Ltd

5. March 2004
Proposal 1
Add a new parameter, BeaconTxTime, to MLME-START.request primitive
BeaconTxTime parameter will be defined as the time, in symbols, to delay from receipt of its parent beacon until the beacon transmission occurs.
Parameter will be ignored if PANCoordinator parameter is TRUE.
Reference point will be the same as macBeaconTxTime.
Phil Beecher, CompXs Ltd

6. Is this a complete solution?
March 2004
Is this a complete solution?
In a word, no!
It provides the means for the network layer to synchronize beacon distribution and hence avoid beacon collision.
It does not solves the problem of CSMA-CA messages trampling beacons of other coordinators
Phil Beecher, CompXs Ltd