1. Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [TG4b MAC backward compatibility]
Date Submitted: [14Sep2004]
Source: [Phil Beecher] Company [CompXs Ltd]
Address [Robert Denholm House, Bletchingley Road, Nutfield, RH1 4HW, UK]
Voice:[ ],
Re: [ nn-4b]
Abstract: [Requirements for backward compatibility]
Purpose: [To focus resolutions for MAC Issues.]
Notice: This document has been prepared to assist the IEEE 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
January 2004
Phil Beecher, CompXs Ltd
Phil Beecher, CompXs Ltd

2. MAC Backward Compatibility
January 2004
MAC Backward Compatibility
Compatibility requirements:
Over air compatibility
MAC layer primitive compatibility
Phil Beecher, CompXs Ltd
Phil Beecher, CompXs Ltd

3. Over air compatibility
Requirements
At a minimum, a b network must coexist with a network
This must include the following:
The .4b specification shall ensure that .4 devices are able to correctly interpret or ignore frames from .4b network.
.4b devices shall be capable of correctly interpreting frames from .4 networks for supported modes of operation.
This implies frames over air must be "compatible”
Current header field assignments must be the same.
New uses of previously unused fields must not break .4 definitions/restrictions.
Changes to Frame header fields must not break .4 definitions/restrictions
MAC commands must retain the same values.
The order of MAC command parameter fields must stay the same.
Phil Beecher, CompXs Ltd

4. MAC Layer Primitive Compatibility
Requirement:
to minimise change to existing NHL designs and implementations.
Implication:
The functionality of primitives must either remain the same or be enhanced; it cannot be changed in a way which will necessitate structural design change in the NHL.
Therefore we cannot remove parameters that will adversely affect the flow of the next higher layer.
Cannot remove or reduce functionality of MAC primitives - any new parameter in .4b primitive must have a default value which retains the behaviour of .4 primitive.
Phil Beecher, CompXs Ltd