24 February 2019 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Issues with Beacon-Mode SuperFrame Structure of IEEE 802.15.4-2006] Date Submitted: [15 May, 2007] Source: [Zafer Sahinoglu] Company [Mitsubishi Electric Research Labs] Address [201 Broadway, Cambridge, MA 02139] Voice:[(617) 621-7588], FAX: [617 621 7550], E-Mail:[zafer@merl.com] Re: [N/A] Abstract: [This documents highlights problems with the superframe structure in the IEEE 802.15.4-2006 specification] Purpose: [This document is prepared to launch a Call for Interest] 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. Zafer Sahinoglu, Mitsubishi Electric

Issues with IEEE 802.15.4 MAC (Beacon Enabled Mode) 24 February 2019 Issues with IEEE 802.15.4 MAC (Beacon Enabled Mode) Dr. Zafer Sahinoglu, Dr. Ghulam Bhatti, Dr. Jinyun Zhang MERL-MTL May 15, 2007 Zafer Sahinoglu, Mitsubishi Electric

Outline Motivation Overview of IEEE 802.15.4 Superframe Structure 24 February 2019 Outline Motivation Overview of IEEE 802.15.4 Superframe Structure Issues Summary and Conclusions Zafer Sahinoglu, Mitsubishi Electric

24 February 2019 Motivation Wireless sensor networks are increasingly being deployed in residential and industrial applications There are many applications with low latency and high reliability requirements IEEE 802.15.4-2006 offers a beacon-mode to support low latency applications IEEE 802.15.4-2006 is underutilizing communication resources (bandwidth, time, power etc) IEEE 802.15.4-2006 MAC beacon-enabled mode needs major modification Zafer Sahinoglu, Mitsubishi Electric

IEEE 802.15.4 Super Frame Structure (Overview) 24 February 2019 IEEE 802.15.4 Super Frame Structure (Overview) In the beacon enabled hybrid mode, the superframe consists of a beacon, CSMA period (CAP), TDMA period (CFP) and an inactive period The idea was to allow messages that require low latency and high reliability use guaranteed time slots (GTS) beacon Superframe interval beacon Beacon interval GTS CAP CFP Inactive CAP GTS GTS GTS Zafer Sahinoglu, Mitsubishi Electric

IEEE 802.15.4 Super Frame Structure (Overview) 24 February 2019 IEEE 802.15.4 Super Frame Structure (Overview) The CFP period consists of 7 GTS Allocation of GTSs is managed centrally by the PAN coordinator beacon Superframe interval beacon Beacon interval GTS CAP CFP Inactive CAP GTS GTS GTS Zafer Sahinoglu, Mitsubishi Electric

Issues (1): Insufficient number of GTSs 24 February 2019 Issues (1): Insufficient number of GTSs If 10 coordinators are connected to the PAN coordinator Only 7 of them can use GTS in the same superframe PAN coordinator Coordinator Zafer Sahinoglu, Mitsubishi Electric

Issues (2): Centralized GTS Management 24 February 2019 Issues (2): Centralized GTS Management Device A can’t use GTS to communicate with its parent C or peer B B C A Zafer Sahinoglu, Mitsubishi Electric

Issues (3): Problematic Retries for GTS <month year> doc.: IEEE 802.15-<doc#> 24 February 2019 Issues (3): Problematic Retries for GTS IEEE 802.15.4-2006 MAC is not well designed for low-latency and high reliability applications GTS is defined for latency sensitive transmissions. However, If the transmission fails, it is a very bad day for you – wait for the next superframe to retransmit Even a successfully received frame shall wait for the next superframe for forwarding to a next hop beacon Superframe interval beacon Beacon interval GTS CAP CFP Inactive CAP GTS GTS GTS DATA ACK This is only one hop latency Can be in the order of seconds and even minutes You can at the earliest transmit here, if you can grab the channel Zafer Sahinoglu, Mitsubishi Electric <author>, <company>

Summary and Conclusions 24 February 2019 Summary and Conclusions The beacon-enabled mode in the current spec is far from supporting low-latency and high reliability applications We would like to issue a Call For Interest for modification of the superframe structure for beacon-enabled mode of IEEE 802.15.4-2006 Zafer Sahinoglu, Mitsubishi Electric