1. doc.: 15-10-0290-00-004e Submission May 2010 Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [A comment for ABT update] Date Submitted: [17 May 2010] Source: [Liang Li, Betty Zhao, Tao Xing] Company [Huawei, SIMIT, Vinno] Address: [Beijing, China] Voice: [+86 10 82836328], FAX: [+86 10 82836920], E-Mail: [liang_1@yahoo.com, betty.zhao@huawei.com] Re: [Letter ballot for 802.154e draft] Abstract:[A comment for ABT update] Purpose:[Comment] 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.

2. doc.: 15-10-0290-00-004e Submission May 2010 Slide 2 ABT update in current draft In draft - (P166 L34~35) On receipt of an DSME handshake command indicating an DSME deallocation notify, … the device updates its ABT to reflect the neighbors deallocated DSME. - (P166 L21~24) On receipt of an DSME handshake command indicating an DSME deallocation reply, … the device updates its ABT to reflect all the neighbors deallocated DSME. A device updates its ABT to reflect the neighbors deallocated DSME slots only when it receives the DSME deallocation reply command or DSME deallocation notify command. Both commands are transmitted by broadcasting. So its probable for the device missing those commands. DSME dealloc req DSME dealloc rep DSME dealloc nof

3. doc.: 15-10-0290-00-004e Submission May 2010 Slide 3 Potential problem If the device misses those commands, it has no chance to update its ABT correctly in the future. Although therere lots of DSME slots in a superframe, accumulation of that problem will also influence the DSME allocation and is nearly impossible to recover. For example, A and B have common vacant slots to communication in fact, but according to ABTs they wont allocate them for each other. ?: non-updated slots, i.e. the slots that were not updated correctly to reflect deallocation. The non- updated slots are selected by the device. Yellow, Orange and Blue: the unavailable slots.

4. doc.: 15-10-0290-00-004e Submission May 2010 Slide 4 Suggested remedy Add a pair of commands ABT update request ABT update reply The device broadcasts ABT update request containing the non-updated slots to its neighbors. If the non-updated slots are being used by the neighbor, the neighbor sends back ABT update reply. If not, the neighbor ignores the command and the device updates ABT. Update ABT 00001000 00000000 00001000 00000000 ABT update req ABT update rep