1. Source: [Chunhui Zhu] Company [Samsung]
September, 2007
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Technical Discussion - Network Formation and Device Joining]
Date Submitted: [Sep 17, 2007]
Source: [Chunhui Zhu] Company [Samsung]
Address [75 W Plumeria Dr. San Jose, CA 95134]
Voice:[ ], FAX: [ ],
Re: []
Abstract: [This is for the discussion on low rate WPAN mesh.]
Purpose: [for discussion and reference]
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
Chunhui Zhu / Samsung

2. Network Formation and Device Joining
September, 2007
Network Formation and Device Joining
Chunhui (Allan) Zhu
September 17th, 2007
Samsung Electronics
Chunhui Zhu / Samsung

3. September, 2007
Outline
Services provided by MAC for forming and joining a network
Channel Scan
Two approaches in mesh layer
Comparison
Conclusion
Chunhui Zhu / Samsung

4. Services provided by 802.15.4 MAC
September, 2007
Services provided by MAC
provides the following mechanisms (primitives) for forming and joining a network
Channel Scan
Association/Disassociation
Orphan
Start
Chunhui Zhu / Samsung

5. Channel Scan Energy Detection Scan Active Scan Passive Scan
September, 2007
Channel Scan
Energy Detection Scan
For PAN Coordinator to select a channel on which to operate prior to starting a new PAN.
Active Scan
Allows a device to locate any coordinator transmitting beacon frames within its POS.
Work only in non-beacon mode.
Passive Scan
It is the same as Active Scan except that the beacon request command is not transmitted.
To be used only in beacon-enabled networks.
Orphan Scan
Allows a device to relocate its coordinator following a loss of synchronization.
Chunhui Zhu / Samsung

6. Two Approaches (1/2) Approach 1 Current approach
September, 2007
Two Approaches (1/2)
Approach 1
Current approach
3 mesh layer primitives:
Discovery (MAC: Active Scan)
Start Mesh (MAC: ED Scan, Active Scan, and Start)
Join (MAC: Active Scan, and Associate)
Procedure:
Use Discovery for gathering network information (Active Scan), such as which networks are out there. The result is not used for starting a mesh or a device.
Use Start Mesh to find appropriate channel (ED Scan), find existing networks (Active Scan) and select PAN ID, then start the network (Start).
Use Join to find existing networks (Active Scan), select and join the network (Associate).
Chunhui Zhu / Samsung

7. Two Approaches (2/2) Approach 2:
September, 2007
Two Approaches (2/2)
Approach 2:
Approach suggested during the comment resolution
3 mesh layer primitives (same as #1 but different meanings):
Discovery (MAC: Active Scan, sometimes ED Scan)
Start Mesh (MAC: Start)
Join (MAC: Associate)
Procedure:
Step 1: Use Discovery to find existing networks (Active Scan),
if PAN found, join it (step 3);
if PAN not found,
MC-capable: ED Scan, start a new one (step 2).
Non-MC-capable: joining failed. Wait and try to join again.
Step 2: Use Start Mesh to start a mesh network (Start).
Step 3: Use Join to join the network (Associate).
Chunhui Zhu / Samsung

8. Comparison Approach 1 Approach 2 Advantages Disadvantages
September, 2007
Comparison
Approach 1
Approach 2
Advantages
Each mesh layer primitive has a clear function.
One primitive for one completed process. NHL does not need to participate in the intermediate process.
By using the results from Discovery primitive, Start Mesh and Start Device do not need to scan again (no function overlap).
Disadvantages
Result of Discovery not used for starting a network or a device.
Some function overlaps in different primitives.
Use two primitives (processes) for one process (start mesh or start device).
Discovery results will be sent to the NHL for it to issue the second primitive. NHL has to involve in the intermediate process. This is an extra burden for the NHL.
Chunhui Zhu / Samsung

9. September, 2007
Conclusion
Prefer to keep the current solution for mesh network forming and device joining processes.
Chunhui Zhu / Samsung

10. September, 2007
TG Conclusion
During the discussion, the group came to the following conclusion:
Take the first approach with the following modification.
Make the active scan (at MAC layer) of the Join primitive optional.
Add two more fields to the Join primitive
A DirectJoin flag
The device address of the parent node this node wants to join directly.
This approach allows flexibility of either joining an specific parent node directly or joining the existing network based on the result of active scan.
Modified Operation of this approach
The NHL can decide whether to join a specific node directly or join an existing network based on the result of active scan.
If the DirectJoin flag is set and a parent device address is provided in the Join primitive, the active scan will be skipped and the device will join the parent node directly (The next higher layer can do this because the Discovery primitive can provide channel conditions for it to make a decision on which parent node to join).
Otherwise, the active scan will be performed and the result will be used for joining the network.
Chunhui Zhu / Samsung