UWB PAC Network Synchronization and Superframe

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [UWB PAC Network Synchronization and Superframe] Date Submitted: [28thJuly 2016 ] Source: [Billy Verso] Company: [DecaWave] Address: [Adelaide Chambers, Peter Street, Dublin 8, Ireland] Voice:[1353 1 6975030] Fax:[] E−Mail:[billy.verso “at” decawave.com] Re: [The MAC “sync” frame format and superframe organization for UWB PHY usage] Abstract:[Presents a sync frame format and its usage for UWB PAC network operation] Purpose:[Material for discussion in IEEE 802.15 TG8] 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. Verso (DecaWave)

2. Introduction • This presentation outlines a method of support for standalone UWB operation for PAC networks, including synchronisation and CFP usage within the superframe. • UWB has no “sync” signal, so needs a MAC sync frame • UWB does not support CSMA/CA instead it uses Aloha • UWB frames are relatively long so cannot fit in the sync period defined for OFDM • for UWB the superframe periods are redefined • the overall length of the superframe is kept the same • The sync frame carries the “discovery information” and also indicates CFP usage Verso (DecaWave)

3. Superframe structure for UWB usage • Sync Period is used for sending sync frames • Sync TX slot is randomly chosen every time PD transmits (aloha), NB: in the UWB modulation when their is a in a collision between two transmissions one of the frames is often received • CAP is used for peering and other MAC procedures and general application usage (e.g. data communication and ranging) • CFP is only for application use (data communication & ranging) Verso (DecaWave)

4. MAC Sync Frame for UWB usage Verso (DecaWave)

5. Operation outline (p1) • A PD starting, listens for sync for a superframe period or 2 • If sync is received the PD aligns its sync TX & superframe to this • Otherwise the PD just sends its (non-aligned) syncs, randomly choosing (for every transmission) which sync period slot to use • While sending sync a PD shall listen for sync from other PD in the sync period • A lone PD periodically listens for the whole superframe period to find other PD sending SYNC and align to their superframes, • how often this is done is an application decision/configuration • Over time a PD listening in the sync periods will hear and know about neighbour PD / Groups and their CFP usage. • The PD sending Sync shall indicate (in the LPDI) a measure of the air-fullness. Verso (DecaWave)

6. Operation outline (p2) • The Local PD density indication (LPDI) gives a measure of the fullness of the air: • How many other PD sync it has heard in the last 10s (say). • How full the CFP is based on the CFP usage indicated in the sync frames it has received. • TBD: encoding of LPDI, is this 1 or 2 octets long • LPDI has two uses: • (a) Sync alignment: if two unaligned PD networks find each others sync, those with lower LPDI shall move to higher density one. i.e. so there will be less PD moving their sync. • (b) Avoidance of interference: It might inform a decision to use another channel/preamble code, i.e. a group leader may decide to operate (or move) its group to another less busy channel or preamble code selection. Verso (DecaWave)

7. Operation outline (p3) • In the sync a PD advertises its discovery info and its willingness to accept peering from other PD wanting to join its group • After peering has admitted appropriate peers, the group may be closed, i.e. the initiator/group leader may stop accepting peering. • The group leader publishes its application’s CFP usage the sync frame, e.g. for periodic ranging exchanges within its group • The group leader chooses its CFP usage, taking into account the CFP usage advertised by other group leaders, i.e. it listens to other groups usage and chooses a non-conflicting set (or it might move to another channel or preamble code) • While periodic ranging/communications is active, the group members may stop sending sync, since the leader’s sync is sufficient to advertise the group’s presence and CFP usage. Verso (DecaWave)

8. Operation outline (p4) • The intention/assumption is that the PD group members will generally do their ranging (and communication) during the CFP slots advertised by the group leader’s sync • of course CAP may also be used for such communications as an alternative • IEs are used (by the group leader) to (a) Tell the group (multicast) and individuals members (unicast) where their interaction periods are: • Specify the interaction start time within the superframe, and if it is not occurring every superframe also indicate the frequency, and timing of next one. • Two use case: (1) tell the group about changes in group slot usage, (2) define individual interaction period for individual nodes in the group (b) Provide a time correction to nodes that only wake-up to range/communicate in their allotted CFP slot. • The exact format/parameters of these IEs is to be defined Verso (DecaWave)

9. The end Verso (DecaWave)