1. November 2008
Project: IEEE P 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: ,
Re: [IEEE TG4e]
Abstract: [This document presents the distributed channel hopping MAC for industrial applications.]
Purpose: [Discussion in e Task Group]
Notice: This document has been prepared to assist the IEEE P 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 P
Anseok Lee

2. 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

3. November 2008
Motivation
Enhance IEEE 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

4. 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

5. 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

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

7. 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

8. 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

9. 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

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

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

12. 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

13. 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

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

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

16. 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

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

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

19. 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

20. November 2008
Star-Mesh Support
In channel hopping system, the number of offset is limited (16 with IEEE 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

21. 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

22. Summary Proposed Cyclicframe structure
November 2008
Summary
Proposed Cyclicframe structure
More flexibility structure than IEEE 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

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