November 2008 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Distributed channel hopping MAC for industrial applications] Date Submitted: [November, 2008] Source: [Anseok Lee, Wun-Cheol Jeong, Seong-Soon Joo ] Company [ETRI] Address: [161 Gajeong-Dong, Yuseong-Gu, Daejeon, Republic of Korea ] E−Mail: [alee@etri.re.kr, wjeong@etri.re.kr , ssjoo@etri.re.kr] Re: [IEEE 802.15 TG4e] Abstract: [This document presents the distributed channel hopping MAC for industrial applications.] Purpose: [Discussion in 802.15.4e Task 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. Anseok Lee

Distributed Channel Hopping MAC for Industrial Applications November 2008 Distributed Channel Hopping MAC for Industrial Applications Anseok Lee, Wun-Cheol Jeong, 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. Anseok Lee

November 2008 Motivation Enhance IEEE 802.15.4-2006 MAC to meet the requirements for industrial applications Low power consumption Superframe structure : Cyclicframe structure based on TDMA Reliability TDMA Channel hopping Mesh networking Scalability Distributed management (Association, timeslot allocation) Star-Mesh topology for high-density networks Anseok Lee

Cyclicframe structure November 2008 Cyclicframe structure Beacon Period (BP) Transmit and receive beacon frame of neighbor mesh node Access via common channel Mesh CAP (MCAP) Exchange control frames between mesh nodes (Association, Timeslot negotiation) Slotted Period (SP) Transmit and receive data frames TDMA with Channel hopping Anseok Lee

Cyclicframe structure November 2008 Cyclicframe structure Beacon-enabled operation Enable peer-to-peer communication among mesh nodes Time sync. via beacon frame Simple network formation and timeslot management Beacon and control frame delivery on common channel Flexible structure Structure can be adapted to the application requirements e.g.) low-power application, MCAP=2, SP=256 (less than 1% duty cycle) Anseok Lee

Channel Hopping operation November 2008 Channel Hopping operation Channel hopping Sample hopping sequence : 20, 25, 13, 22, 17, … Anseok Lee

Channel Hopping operation November 2008 Channel Hopping operation Channel hopping (i.e. 2 nodes) Sample hopping sequence : 20, 25, 13, 22, 17, … When hopping offset value is 2 : 13, 22, 17, … Anseok Lee

Distributed Channel Hopping operation November 2008 Distributed Channel Hopping operation Each Mesh node owns a Cyclicframe, i.e.: Each mesh node has its own offset value Each mesh node can manage its own timeslots 2 Anseok Lee

Distributed Channel Hopping operation November 2008 Distributed Channel Hopping operation Timeslot operation Idle timeslot : No Tx and Rx Rx timeslot Tune to its own channel Enable receiver Receive data frame Turn to Tx mode Transmit Ack frame Tx timeslot Jump to the receiver’s channel Transmit data frame Turn to Rx mode Receive Ack frame 2 Anseok Lee

Data Frame Transmission - sender November 2008 Data Frame Transmission - sender 2 Anseok Lee

Data Frame Transmission - receiver November 2008 Data Frame Transmission - receiver 2 Anseok Lee

Distributed Hopping Offset Assignment November 2008 Distributed Hopping Offset Assignment Empty offset selection - example node 1’s Neighbor offset bitmap = {1,3,6,10} node 3’s Neighbor offset bitmap = {1,3,12,13} node 6’s Neighbor offset bitmap = {1,2,6,9} node 12’s Neighbor offset bitmap = {3,12} Available offsets = {0,4,5,7,8,11,14,15} Anseok Lee

Association Association November 2008 Association Association For more reliable association, use three-way handshaking method (request, response, notification) Notification to inform the address and offset of joining node to neighbor nodes If duplication of offset is detected, neighbor mesh node send Offset Duplicated message Procedure Newly joining node send Association Request to a mesh router Parameter : device type, capability Mesh router reply Association Response to joining node Check resources and the capability of joining node Allocate node address if required Joined node broadcast Association Notification Anseok Lee

Association - originator November 2008 Association - originator Association Request Anseok Lee

Association - recipient November 2008 Association - recipient Association Reponse Acknowledge Anseok Lee

Distributed Timeslot Allocation November 2008 Distributed Timeslot Allocation Distributed Timeslot Allocation Timeslot allocation will occur in MCAP Sender transmit Channel Request Message (CRM) Source, destination addresses Traffic information (data size, interval, priority) Available timeslots (bitmap) etc. Receiver reply Channel Grant Message (CGM) Allocated timeslots (bitmap) Life time (# of cyclicframe) Anseok Lee

Timeslot Allocation - sender November 2008 Timeslot Allocation - sender A B C E D Timeslot Request D’s available timeslot : 1 0 0 1 1 0 0 1 1 1 1 1 Anseok Lee

Timeslot Allocation - receiver November 2008 Timeslot Allocation - receiver A B C E D Timeslot Response D’s available timeslot : 1 0 0 1 1 0 0 1 1 1 1 1 E’s available timeslot : 0 1 1 0 0 1 1 1 1 1 1 1 Allocated timeslot : 0 0 0 0 0 0 0 1 1 0 0 0 Anseok Lee

Beacon Transmission Beacon Transmission November 2008 Beacon Transmission Beacon Transmission Mesh nodes periodically transmit its beacon frame to neighbors in BP To avoid collision, beacon transmission should be scheduled carefully Each mesh node has its own offset value which is not used by 2-hop neighbors Instead of additional beacon scheduling method, we use offset value to schedule beacon frames Anseok Lee

November 2008 Star-Mesh Support In channel hopping system, the number of offset is limited (16 with IEEE 802.15.4 PHY) Limits number of mesh node (less or equal to 16 in a collision domain) When number of node increases, the available offset is depleted Star connection to mesh node support high density network Anseok Lee

Star-Mesh Support Star-Mesh Support November 2008 Star-Mesh Support Star-Mesh Support If Star-mesh support flag is true, the first two timeslot is used for timeslot allocation for End node A node can join to the network as an End node Associate to a mesh node without offset value End node which has data to send transmit CRM at first timeslot Based on CRM from End nodes, Mesh node announces Star Schedule Allocation (SSA) at second timeslot Anseok Lee

Summary Proposed Cyclicframe structure November 2008 Summary Proposed Cyclicframe structure More flexibility structure than IEEE 802.15.4-2006 Superframe structure Distributed Channel hopping operation and TDMA channel access Support deterministic data transfer Improved reliability and scalability Star-Mesh topology Support large-scale and high-density network Anseok Lee

Thank you very much for your attention! Any Questions? November 2008 Thank you very much for your attention! Any Questions? Anseok Lee