Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Out-of-band control frame structure to enhance IEEE802.15.4-2006 MAC] Date Submitted: [July, 2008] Source: [Wun-Cheol Jeong (1), Jong-Moon Chung (2), Chang-Sub Shin (1), Anseok Lee (1), Seong-Soon Joo (1)] Company [ETRI (1), Yonsei University (2)] Address [161 Gajeong-Dong, Yuseong-Gu, Daejeon, Republic of Korea (1), Shinchon-Dong 134, Seodaemun-Gu, Seoul, Republic of Korea (2)] E−Mail [wjeong@etri.re.kr (1), jmc@yonsei.ac.kr (2), shincs@etri.re.kr (1), alee@etri.re.kr (1), ssjoo@etri.re.kr] Re: [802.15.4e group] Abstract: [This document presents concepts providing reliable but fast channel access for dynamic heterogeneous traffic.] Purpose: [Discussion in 802.15.4e Study Group] 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. W.-C. Jeong

2. Out-of-band control frame structure to enhance IEEE802.15.4-2006 MAC Wun-Cheol Jeong, ETRI Jong-Moon Chung, Yonsei University Chang-Sub Shin, ETRI Anseok Lee, ETRI Seong-Soon Joo, ETRI This work has been supported by the Ministry of Knowledge Economy (MKE) of the Republic of Korea under Grants 2008-F-052. W.-C. Jeong

3. Motivation • Current Superframe structure is not flexible to accommodate dynamic traffic. • QoS provision may require more robust control of bandwidth requests instead of competing with data frame in CAP. Flexible but robust out-of-band control frame may provide efficient channel access. • Many services including industrial applications, require reliable and fast channel access for communications. W.-C. Jeong

4. Limitations on current GTS management • In current Superframe structure, • GTS requests • should compete with data frames in the CAP. -> This would increase collision probability, which reduces reliability. • acknowledged in the next beacon period -> Latency is introduced. • maximum number of GTS is limited to 7. -> inefficient in overloaded network • QoS provision is difficult -> CAP vs. CFP W.-C. Jeong

5. CAP1 SSA1 CAP2 SSA2 TS1 TS2 … TS# Control-Part Data-Part Superframe Proposed Superframe Structure • Superframe consists of a Control-Part and a Data-Part • Superframe Control-Part • During the CAP1 reservation period, a node which has data to send transmits a Channel Request Message (CRM) during CAP. • Superframe Data-Part • Based on Superframe Schedule Assignment (SSA) the Superframe Data Part assigns one or multiple time-slots to each node. • After the Superframe Data-Part the Superframe ends and a new Superframe begins with a new Control-Part. W.-C. Jeong

6. Superframe Control-Part • During the CAP1 reservation period, a node which has data to send transmits a Channel Request Message (CRM). • CRM includes: • Source Address (SA) • Destination Address (DA) • Traffic Length Indicator (TLI) • Optional information (e.g., transmission data size, transmission period, traffic priority, sensor type, alarm type, etc.) • Based on the channel request messages in CAP1, the Superframe Schedule Assignment 1 (SSA1) is announced. • SSA1 includes the SA, DA, and Time-Slot Assignments of the Superframe. • Based on SSA1, some nodes may realize that their CRM sent during CAP1 was not accepted and during CAP2 (using random access time selection) will send another CRM. • Under heavy traffic conditions, this will allow nodes that have failed to obtain transmission access in the Superframe to have a second chance to obtain transmission access. • Under low traffic conditions, the second CAP can be skipped. W.-C. Jeong

7. Superframe Control-Part (continued) • Based on the channel request messages of CAP1 and CAP2, the Superframe schedule Assignment 2 (SSA2) is announced. • Traffic Load Dependent Configurations • During the network Initialization period a longer control-part could be beneficial. • Reservations made to slot assignments can be carried over to multiple Superframes. • Some nodes can request for channel access for very long durations (using the CRM). • Since this may make the Superframe too long (and also less flexible to short term request users), the SSA can indicate that for some nodes their reservation of time slots will automatically extend into the following Superframe. • The nodes that have been granted this extension assignment should not send a CRM in the following CAP. W.-C. Jeong

8. Superframe Data-Part • Based on SSA2 (or SSA1 for low traffic connditions) the Super Frame Data Part assigns one or multiple time-slots to each node to be used during a single Superframe duration. • For each node, the number of multiple time-slots during a singleSuperframe duration will be based on the TLI and optional information (e.g., transmission data size, transmission period, traffic priority, sensor type, alarm type, etc.) submitted by the CRM. • After the Superframe Data-Part the Superframe ends and a new Superframe begins with a new Control-Part. W.-C. Jeong

9. CAP1 SSA1 CAP2 SSA2 CAP3 SSA3 … TS# Control-Part Data-Part Superframe CAP1 SSA1 CAP2 SSA2 TS1 TS2 … TS# Control-Part Data-Part CAP1 SSA1 TS1 TS2 TS3 TS4 … TS# Superframe Control-Part Data-Part Superframe Proposed Superframe Structure • Initialization Phase: Extended Reservation & Scheduling Control-Part • For moderate to high traffic (also, support for star-mesh topology) • For low traffic W.-C. Jeong

10. July 2008 Summary • Dynamic frame structure: • Proposed Superframe structure enables to accommodate dynamic traffic condition with high reliability. • CRM/SSA: • Proposed channel request/grant mechanism (CRM/SSA) reduces channel access latency and collision probability. • TLI: • Timeslots are reserved based on transmission data size and transmission period information, which allows efficient time-slot management. • Urgent message can be reliably delivered by exploiting data type. Slide 10 W.-C. Jeong

11. Thanks ;) W.-C. Jeong