1. <month year>
doc.: IEEE
July 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [IEEE WPAN Mesh Networks Summary]
Date Submitted: [19 July, 2005]
Source: [Jianliang Zheng, Yong Liu, Chunhui Zhu, Marcus Wong, Myung Lee] Company [Samsung]
Address [Samsung Steinman Hall, 140th St & Convent Ave, New York, NY 10031, USA]
Voice:[ ], FAX: [ ],
Re: [Call for Proposal: IEEE P /0071]
Abstract: [This document discusses Samsung’s proposal for IEEE WPAN Mesh, based on Meshed-Tree approach.]
Purpose: [This proposal is provided to be adopted as a recommended practice for IEEE WPAN Mesh]
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
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

2. IEEE 802.15.5 WPAN Mesh Networks
July 2005
IEEE WPAN Mesh Networks
Jianliang Zheng, Yong Liu, Chunhui Zhu, Marcus Wong, Myung Lee
Samsung CUNY
Zheng, Liu, Zhu, Wong, Lee

3. July 2005
Objectives
To construct Mesh Networking Layer over IEEE MAC and PHY
Proposed Mesh Network includes following features:
Meshed Tree Formation
Block Addressing
Routing
Multicasting*
Key Pre-distribution**
Extensible to IEEE MAC and PHY
*, ** Refer to mesh-networks-samsung
Zheng, Liu, Zhu, Wong, Lee

4. Contents Meshed tree approach Centralized approach July 2005
Zheng, Liu, Zhu, Wong, Lee

5. July 2005
Meshed Tree
Zheng, Liu, Zhu, Wong, Lee

6. Outline Adaptive Robust Tree (ART) Mesh Networking Summary ART
July 2005
Outline
Adaptive Robust Tree (ART)
ART
Meshed ART (MART)
Mesh Networking
Data Forwarding
Route Discovery
Tree Route Repair
Summary
Zheng, Liu, Zhu, Wong, Lee

7. ART: Initialization Phase
<month year>
doc.: IEEE
July 2005
ART: Initialization Phase
[children#][children#]=[8][6] A
[beg,end,next]=[1,16,1] [beg,end,next]=[17,28,17]
Stage 1: Association
[5][2]
[5] B J
Stage 2: Reporting number of children
[3,12,3] [13,16,13]
[19,28,19] C H K
[1][2][1]
[3][1]
[1]
Stage 3: Address assignment
An ART is formed.
Additional addresses can be reserved.
[5,6,5] [7,10,7] [11,12,11]
[21,26,21] [27,28,27]
[15,16,15] D E G I L O
[1][1]
[0]
[0]
[1]
[0]
[0]
[23,24,23] [25,26,25]
[9,10,9] F M N
[0]
[0]
[0]
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

8. ART: Normal Phase Normal data transmissions
July 2005
ART: Normal Phase
[8][6]
A 0
Normal data transmissions
[1,16,1]
[17,28,17]
[5][2]
[5]
B 1
J 17
[3,12,3] [13,16,13]
[19,28,19]
Example:
Node C  node L
C 3
H 13
K 19
[1][2][1]
[3][1]
[1]
Nodes are still allowed to join the network
[5,6,5] [7,10,7] [11,12,11]
[21,26,21]
[15,16,15]
[27,28,27]
D 5
E 7
G 11
I 15
L 21
O 27
[1][1]
[0]
[0]
[1]
[0]
[0]
[23,24,23] [25,26,25]
[9,10,9]
F 9
M 23
N 25
[0]
[0]
[0]
Zheng, Liu, Zhu, Wong, Lee

9. Neighbors treat each other as a child.
July 2005
Meshed ART (MART)
Neighbors treat each other as a child.
[8][6]
[1,16,1] [17,28,17]
A 0
[5][2]
[5]
[3,12,3] [13,16,13]
[19,28,19]
B 1
J 17
[1,16,1]
[17,28,17]
[13,16,13]
Shorter path C
H 13
[1] K
[15,16,15]
Elimination of SPOFs
[17,28,17] …… D E G I L O F M N
Zheng, Liu, Zhu, Wong, Lee

10. Data Forwarding Start July 2005 Find an optimal route in NTT?
route in ARTT?
Find an auxiliary
Use the route found
Start
Use tree route 1 2 4 3 Y N
Optimal routes
Non-optimal routes
Zheng, Liu, Zhu, Wong, Lee

11. Route Discovery (1) Case 1: Source has an optimal route
July 2005
Route Discovery (1) A
Case 1: Source has an optimal route
No route discovery B J C H K D E G I L O
Example 1: node F  node I (optimal non-tree route) F M N
Example 2: node J  node M (optimal tree route)
Optimal non-tree route
Optimal tree route
Zheng, Liu, Zhu, Wong, Lee

12. <month year>
doc.: IEEE
July 2005
Route Discovery (2) A B J E D C I H K L O G F M N
Case 2: Source has no optimal route; but destination has.
dst.
Example 1: node F  node I
Bi-directional routes are set up
dst.
Here only give an example that destination has an optimal non-tree route;
The case that destination has an optimal tree route can be more easily handled.
Example 2: node N  node J
No routing entry created
src.
src.
unicast RREQ
unicast RREP
existing optimal non-tree route
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

13. <month year>
doc.: IEEE
July 2005
Route Discovery (3) A
Case 3: Neither the source nor the destination has optimal route. B J C H K
Example: node I  node O D E G I L O
src.
dst.
Source will time out if the unicast RREQ does not get through; then the source will flood an RREQ. F M N
unicast RREQ
broadcast RREQ
RREP
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

14. Tree Route Repair Node K fails
<month year>
doc.: IEEE
July 2005
Tree Route Repair A
Node K fails
Node J broadcasts an RREQ to locate node K, with a limited TTL. B J C H K
All nodes below node K that have received the RREQ reply. D E G I L O
Node J selects the best path and sends an RCFM to activate it.
If no reply, node J will increase TTL and try again.
An RERR will be sent to the source if several tries fail.
Not all broadcast propagations are shown in the Figure.
Multiple branches (e.g, also branch O) can be repaired during above procedure. F M N
MART route
RREP
RREQ
RCFM
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

15. Tree Route Repair (cont.)
<month year>
doc.: IEEE
July 2005
Tree Route Repair (cont.)
Data Forwarding after tree route repair A
[desIn,19,28,down,19]
[desIn,21,26,normal,13] B
J 17 C
H 13 K
[desIn,21,26,normal,21]
[srcIn,21,26,normal,17]
Note the entry [srcIn,21,26,normal,17] at node H may be ignored if there is another high priority entry.
For example, the path from node M to node C will be M  L  H  C. D E G I
L 21 O
[1][1]
[23,24,23] [25,26,25]
parent=13 F M N
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

16. Summary Adaptive address assignment Efficient tree repair
<month year>
doc.: IEEE
Summary
July 2005
Adaptive address assignment
avoiding “running out of addresses” problem
Efficient tree repair
no address re-assignment
Meshed ART (MART)
shorter path
Robustness
Mesh networking (Tree routing + Non-tree routing)
optimal routes
no broadcast (even with limited TTL) if either the source or the destination has an optimal route
no flooding if there is a (non-optimal) route from the source to the destination
Note that there is no RTS/CTS in
Zheng, Liu, Zhu, Wong, Lee
Zheng, Liu, Zhu, Wong, Lee, Samsung

17. July 2005
Centralized Approach
Zheng, Liu, Zhu, Wong, Lee

18. Basic Mechanisms Tree formation Tree addressing Tree routing
July 2005
Tree formation
Tree addressing
Tree routing
Topology server setup
Beacon scheduling
Reactive shortcut formation
Two-address strategy
Route repair
Zheng, Liu, Zhu, Wong, Lee

19. Tree Formation
July 2005
The node initiating the network becomes the PAN coordinator.
In the network formation stage, all coordinators shall enable their receivers to catch beacon requests from new nodes.
No regular beaconing is allowed before the beacon scheduling is done.
New nodes perform active scan to collect beacons from their neighbors.
Every new node selects a neighbor, which has the best path quality to the PAN coordinator, as its parent.
Zheng, Liu, Zhu, Wong, Lee

20. Tree Addressing
July 2005
Zheng, Liu, Zhu, Wong, Lee

21. Tree Routing Node H sends a packet to node F.
July 2005
Node H sends a packet to node F.
As H does not have any child, it forwards the packet to its parent C.
C finds that F has an address out of its address block. So it forwards the packet to its parent A.
As F’s address falls into A’s address block, and A further finds that F’s address is between the addresses of child B and C, so A forwards the packet to B.
B forwards the packet to F.
Zheng, Liu, Zhu, Wong, Lee

22. Topology Server Setup
July 2005
Either the PAN coordinator or a resource sufficient node can serve as the topology server.
All other nodes can reach the topology server by using tree routing.
Each coordinator shall report its superframe parameters and link states to the topology server.
Each coordinator may periodically scan its neighbors' beacons and report significant link changes to the server.
There can be two or more topology servers acting as backup of each other.
Zheng, Liu, Zhu, Wong, Lee

23. Beacon Scheduling
July 2005
When receiving the neighboring information of a coordinator, the topology server assigns a contention-free beacon time-slot to the coordinator.
Every coordinator gets a beacon time slot that is not overlapped with the active periods of its two-hop neighbors.
This two-hop beacon scheduling ensures that each node can correctly capture all its neighbors’ beacons and locate their active periods.
Once a coordinator receives the beacon time assignment, it can emit regular beacons and operate in beacon-enabled mode.
Zheng, Liu, Zhu, Wong, Lee

24. Reactive Shortcut Formation
July 2005
An active source sends a shortcut request (SCRQ) message to the topology server.
The topology server calculates the optimal shortcut by using the Dijkstra’s algorithm.
The topology server sends a shortcut notification (SCNF) message to the destination.
The destination sends a shortcut reply (SCRP) message to the source to establish routing entries along the shortcut.
Relay nodes along the shortcut shall locate and record the active periods of their previous-hop and next-hop neighbors.
Zheng, Liu, Zhu, Wong, Lee

25. Summary Establish a self-routing tree to cover the whole network
July 2005
Establish a self-routing tree to cover the whole network
Schedule beacon transmissions at a topology server to avoid beacon collisions
Calculate shortcuts between active source-destination pairs at a topology server to avoid flooding based route discovery
Quickly recover from link/node failures by recalculating new routes or reforming the tree
Zheng, Liu, Zhu, Wong, Lee