Replacement Text and Figures for Section 5.4.3

October, 2004 IEEE 15-04-0568-00-004b

IEEE P802.15

Wireless Personal Area Networks

Project / IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Title / Replacement text and figures for Section 5.4.3
Date Submitted / [01 October, 2004]
Source / [Robert Cragie]
[Jennic Limited]
[Furnival Street, Sheffield S1 4QT, UK] / Voice:[+44 114 281 2655]
Fax:[+44 114 281 2951]
E-mail:[
Re: / [15-04-0239-00-004b-tg4b-call-proposals.doc]
Abstract / [The description of frames in the general description (section 5) of IEEE 802.15.4-2003 is inconsistent with the descriptions in the PHY specification (section 6) and the MAC specification (section 7). This document offers drop-in text and figure replacements for section 5.4.3.]
Purpose / [This document is provided to the TG4b group to help draft clarifying text and diagrams, as per 15-04-0239-00-004b-tg4b-call-proposals.]
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.

Table of Contents

1.INTRODUCTION

Change ‘MSDU’ to ‘MAC Payload’

Non-payload fields

PHY PDU types

2.REFERENCES IN 802.15.4-2003

1.INTRODUCTION

This document proposes drop-in replacements for sections 5.4.3.1, 5.4.3.2, 5.4.3.3 and 5.4.3.4 of 802.15.4-2003. Note this document only covers section 5. It is likely that further clarifications will be required throughout the remainder of the specification to tighten up the use of terminology and this will be considered in another document.

All textual changes are highlighted by using bold italic font.

Change ‘MSDU’ to ‘MAC Payload’

The main change is changing the use of the term ‘MSDU’ to ‘MAC payload’. The MSDU is specifically the service data unit passed over the MAC common part sublayer (CPS) service access point (SAP) via MCPS-DATA.request and MCPS-DATA.indication. It should not be used to describe the MAC payload as it has no relevance to frames that are local to the MAC sublayer, i.e. beacon, acknowledgment and command frames.

Non-payload fields

Another change is to introduce the term ‘non-payload field’. This is referred to in section 7.6.3.3.1 and 7.6.3.3.2 but has no precise definition and thus can cause confusion.

PHY PDU types

Terms such as ‘PHY beacon packet’ are used in 802.15.4-2003. Packets/frames only have implied meaning at the MAC level, therefore it is misleading to label PHY packets in such a manner. All such references have been changed to ‘PHY packet’.

2.REFERENCES IN 802.15.4-2003

5.4.3.1 Beacon frame

Figure 10 shows the structure of the beacon frame, which originates from within the MAC sublayer. A coordinator can transmit network beacons in a beacon-enabled network. The MAC payload contains three non-payload fields (superframe specification, pending address specification and address list) followed by the beacon payload field (see 7.2.2.1). The MAC payload is prefixed with a MAC header (MHR) and appended with a MAC footer (MFR). The MHR contains the MAC frame control fields, beacon sequence number (BSN), and addressing information fields. The MFR contains a 16 bit frame check sequence (FCS). The MHR, MAC payload, and MFR together form the MAC beacon frame (i.e. MPDU).

Figure 10—Schematic view of the beacon frame

The MPDU is then passed to the PHY as the PHY service data unit (PSDU), which becomes the PHY payload. The PHY payload is prefixed with a synchronization header (SHR), containing the preamble sequence and SFD fields, and a PHY header (PHR) containing the length of the PHY payload in octets. The preamble sequence and the SFD enable the receiver to achieve symbol synchronization. The SHR, PHR, and PHY Payload together form the PHY packet (i.e. PPDU).

5.4.3.2 Data frame

Figure 11 shows the structure of the data frame, which originates from the upper layers.

Figure 11—Schematic view of the data frame

The MAC payload contains solely the data payload field, which is the MSDU passed to the MAC sublayer. The MAC payload is prefixed with a MHR and appended with a MFR. The MHR contains the frame control, sequence number, and addressing information fields. The MFR is composed of a 16 bit FCS. The MHR, MAC payload and MFR together form the MAC data frame (i.e. MPDU).

The MPDU is passed to the PHY as the PSDU, which becomes the PHY payload. The PHY payload is prefixed with an SHR and a PHR. The SHR, PHR, and PHY Payload together form the PHY packet (i.e. PPDU).

5.4.3.3 Acknowledgment frame

Figure 12 shows the structure of the acknowledgment frame, which originates from within the MAC sublayer. The MAC acknowledgment frame is constructed from an MHR and an MFR; it has no MAC payload. The MHR contains the MAC frame control and data sequence number fields. The MFR is composed of a 16 bit FCS. The MHR and MFR together form the MAC acknowledgment frame (i.e. MPDU).

Figure 12—Schematic view of the acknowledgment frame

5.4.3.4 MAC command frame

Figure 13 shows the structure of the MAC command frame, which originates from within the MAC sublayer. The MAC payload contains one non-payload field (command type) followed by the command payload field (see 7.2.2.4). The MAC payload is prefixed with an MHR and appended with an MFR. The MHR contains the MAC frame control, data sequence number, and addressing information fields. The MFR contains a 16 bit FCS. The MHR, MAC payload and MFR together form the MAC command frame (i.e. MPDU).

Figure 13—Schematic view of the MAC command frame

The MPDU is passed to the PHY as the PSDU, which becomes the PHY payload. The PHY payload is prefixed with an SHR and a PHR. The SHR, PHR, and PHY Payload together form the PHY packet (i.e. PPDU).

SubmissionPage 1Robert Cragie, Jennic Limited