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: [Cyclicframe structure to enhance IEEE802.15.4-2006 MAC] Date Submitted: [September, 2008] Source: [Wun-Cheol Jeong, Anseok Lee, Chang-Sub Shin , Seong-Soon Joo ] Company [ETRI] Address [161 Gajeong-Dong, Yuseong-Gu, Daejeon, Republic of Korea ] E−Mail [wjeong@etri.re.kr , alee@etri.re.kr, shincs@etri.re.kr, 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. Cyclicframe structure to enhance IEEE802.15.4-2006 MAC Wun-Cheol Jeong, Anseok Lee, Chang-Sub Shin, 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. • Channel hopping provides high reliable link-level connections. However, when nodes are densely populated, the available channels may not be sufficient to establish requested channel connections. • 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. Proposed Cyclicframe Structure • Cyclicframe consists of • Beacon period (BP) • Broadcast beacon frames (TDMA/slotted hopping) • The length of BP and beacon interval value are variable • Mesh contention access period (MCAP) • Transmit channel request/ACK for peer-to-peer (mesh) connection using CSMA/CA Beacon Interval W.-C. Jeong

6. Proposed Cyclicframe Structure • Cyclicframe consists of • Slotted Period(SP) • Transmit/Receive data frames using TDMA/slotted hopping. • Support star connections. • The number of MCAP/SP repetition in a cyclic frame is specified in BP W.-C. Jeong

7. Proposed Cyclicframe Structure • Beacon Period • Beacon frames are transmitted in a predefined channel-time slot period. • A Beacon frame contains • cyclicframe structure information such as beacon interval value, beacon period duration, star topology support flag, etc • time synchronization information • channel hopping information such as channel hopping sequence, offset value 26 14 Channel 13 12 11 1 2 3 4 5 6 Timeslot W.-C. Jeong

8. Proposed Cyclicframe Structure E B • Beacon Period A 26 D 14 Channel C F 13 12 11 1 2 3 4 5 6 Timeslot W.-C. Jeong

9. Proposed Cyclicframe Structure B • Mesh Contention Access Period (MCAP) • Channel request/ACK frames are transmitted using CSMA/CA • Node B who has packets to send transmit channel request message frame (CRM) to node A • Based on the CRM and its own schedule, node A sends ACK frame to node B with Tx schedule. • 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.) D A C F CRM ACK W.-C. Jeong

10. Proposed Cyclicframe Structure B • Slotted Period(SP) • For each node, the number of multiple time-slots during a singlecyclicframe 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 • The node assigned time slots tunes its channel to recipient node’s channel sequence for transmission. D A E F C 6 5 4 Channel 3 2 1 1 2 3 4 5 6 8 7 W.-C. Jeong

11. Proposed Cyclicframe Structure B • Slotted Period(SP) • When the number of node increases, the available channel offset values are depleted. • Star connection is employed to use the finite channel offset values. D A E F C 6 5 4 Channel 3 2 ? ? G 1 H 1 2 3 4 5 6 8 7 W.-C. Jeong

12. Proposed Cyclicframe Structure B • Slotted Period(SP) • The first two slots of channel hopping pattern are used for star connection. (Optional) D A E F C 6 5 4 Channel 3 2 G 1 H 1 2 3 4 5 6 8 7 W.-C. Jeong

13. Proposed Cyclicframe Structure B • Slotted Period(SP) • Star connection • If star topology support flag is true, the first time slot is used for channel request. • A node which has data to send transmits a CRM • Based on the CRMs, the star-connection schedule assignment (SSA) is announced. D A E F C 6 5 4 Channel 3 2 G 1 H 1 2 3 4 5 6 8 7 W.-C. Jeong

14. Summary • Dynamic frame structure: • Proposed cyclic frame structure supports mesh-star connections for high reliable low power connection. • 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 14 W.-C. Jeong

15. Thanks ;) W.-C. Jeong