1. March 2006
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [An Architecture for IEEE WPAN Mesh Network]
Date Submitted: [15 July, 2005]
Source: [Ho-In Jeon (1), Yong-Bae Kim (2), Bum-Joo Kim (2), Jun-Seon Beck (2), Yongsik Shin (3)]
Company: [Dept. Electronic Engineering, Kyung-Won University (KWU) (1), LeiiTech Inc. (2)
SKTelecom (3)]
Address: [San 65, Bok-Jung-Dong, Sung-Nam-Shi, Kyung-Gi-Do, Republic of Korea]
Voice 1:[ ], Voice 2:[ ] FAX: [ ],
Re: [This work has been supported by HNRC of IITA.]
Abstract: [This document proposes an architecture for IEEE WPAN Mesh Network.]
Purpose: [Final Proposal for the IEEE Standard]
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
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

2. An Architecture for IEEE 802.15 WPAN Mesh Network
March 2006
An Architecture for IEEE WPAN Mesh Network
Ho-In Jeon (1), and Yongsik Shin (2)
(1) Kyung-Won University, HNRC of IITA
Republic of Korea, and
(2) SKtelecom
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
March 2006
Contents
Introduction
Issues of mesh networks
Goals of WPAN Mesh Network
A Scenario for the operation of Mesh Network
Proposed Architecture for WPAN Mesh
Superframe Structrue for Mesh Network
Efficient Real-Time Address Assignment vs. ABA
Features of the Proposed Architecture
Conclusion
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom
<author>, <company>

4. Issues of Mesh Networks
<month year>
doc.: IEEE <doc#>
March 2006
Issues of Mesh Networks
Beacon Scheduling for Collision Avoidance
Reduction of Power Consumption with Beacon Network
Non-beacon-Enabled Network cannot provide a power-efficient operational mode
Beacon Aggregation for throughput enhancement in the case of two or more PANs merging.
Efficient Real-Time Short Address Allocation Algorithms
Savings of Address Spaces
Routing Algorithm: Proactive or Reactive
Power-Efficient Operation Mode
Support of Time-Critical or Delay-Sensitive Applications
Adoption of RTS/CTS or resource Reservation for Data Transmission
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom
<author>, <company>

5. Goals of WPAN Mesh Network
<month year>
doc.: IEEE <doc#>
March 2006
Goals of WPAN Mesh Network
High speed as well as Low Speed WPAN
High throughput
Low latency
Sensor Network
Easy Network Configuration
Fast and Efficient Short Address Allocations
Usage of Control Channel with single/multiple transceiver/radio solutions
Centralized/Decentralized Beacon Scheduling and/or Aggregation for spatial frequency reuse
Data services
Isochronous
Asynchronous
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom
<author>, <company>

6. Assumptions for Mesh Network Operations
March 2006
Assumptions for Mesh Network Operations
Devices are associated sequentially, one by one.
No initialization process exists.
The relation between parent and children are characterized by association.
Children are my neighbors.
Parent is also my neighbors.
All devices I can hear are my neighbors.
Solid blue line represents the Parent-Child relations based on associations.
Solid red line represents directly reachable nodes.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

7. A Scenario for Mesh Network Operations
March 2006
A Scenario for Mesh Network Operations 4 9 1 2 6 5 2 9 1 6
PNC 3 4 8 7
Node 1 is the first device turned on.
Node i is the ith device that was associated with the PAN
The number in the dotted circle represents the device of which the Tx range reaches.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

8. PNC Formation of the Mesh
March 2006
PNC Formation of the Mesh 1 1
PNC
Device 1 first scans passively first and actively next.
When it finds that there is no device that he can associate with, it becomes the PNC.
Once a device becomes a PNC, it starts to transmit its beacon at the beginning of the superframe.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

9. Joining of Device 2 to the Mesh
March 2006
Joining of Device 2 to the Mesh 1 2 2 1
PNC
Dev. 2 hears the beacon form PNC and gets associated with it.
When associated, it gets PANID, Short Address, and other sets of information from PNC and determines when to send its beacon.
Dev. 1 and 2 listen to beacons of each other and store information about their neighbor in the Neighborhood Table.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

10. Association Relations and Beacon Tx
March 2006
Association Relations and Beacon Tx
Every mesh device transmits beacon during the BOP (Beacon-Only Period) to save BOP usage.
Beacon scheduling needs to be applied. 2 1
PNC 3
Superframe
Inactive Period
Active Period
BOP
CAP
CTA 1 2 3 1 2 3
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

11. Association and Direct Links Relations
March 2006
Association and Direct Links Relations 4 9 1 2 6 5 2 9 1 6
PNC 3 4 8 7
Superframe
BOP
CAP
CTA
Inactive Period 1 2 3 4 5 6 7 9 1 2 3 8 8
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

12. Association and Direct Links Relations
March 2006
Association and Direct Links Relations 2 5 9 1
PNC 6 8 4 3 7
Blue Line: Association Relations
Red Line: Direct Communication Capable
Association Policy
New nodes are associated with the nodes which are as close to the PNC and possible
If RSSI is not high enough for reliable communications, then it can choose other node as its parent.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

13. Superframe Structure Agreement
March 2006
Superframe Structure Agreement
When a beaconing device powers up, it scan for at least one superframe and shall attempt to join the existing beacon group, if any (better performance)
When two beacon devices (or two groups) observe each other, they shall “cross protect” each other’s beacon transmission (reduced complexity)
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

14. Beaconing Device Powers Up
March 2006
Beaconing Device Powers Up
Every mesh device has to send his beacon.
However, the end device may not be obligated to send his beacon to alleviate the possibilities of beacon conflicts. 2 5 9 1
PNC 6 8 4 3 7
Superframe
BOP
Inactive Period
CAP
CTA 1 2 3 4 5 6 7 9 1 2 3 8 8
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

15. Superframe for Merge of 2 PANs
March 2006
Superframe for Merge of 2 PANs
When superframe sizes of the two PANs are different, the channel utilization becomes poor.
It is recommended to have aggregated beacons in the beginning of the superframe even when two PANs are merged.
Intervals that cannot be used for data transmissions
Superframe of PAN 1 A B C A B C D E F D E F D E F
Superframe of PAN 2
Superframe of PAN 2
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

16. Thoughts on Fully Distributed Mesh
March 2006
Thoughts on Fully Distributed Mesh
PAN ID
This is acquired by PNC at his own will.
Without same PAN ID, no communication can be made.
PAN ID information must be delivered to every device of the PAN
Beacon Transmission Start/End Time
This information must be disseminated all over the PAN to allow new DEV to pick up his Beacon Transmission Time.
Short Address Conflicts
Not sure if there is a perfect mechanism to avoid the short address conflicts
A (reference) node may solve this problem for a special case.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

17. Short Address Allocations
March 2006
Short Address Allocations
Hierarchical Block addressing wastes address space.
Centralized Address allocations
May take too much time for the address allocation.
Distributed Address allocations
No guarantee way of avoiding address conflicts.
A mechanism of assigning short addresses in real-time in an efficient way that can prevent address conflict has been needed.
Combination of the two mechanisms.
Beacon Scheduling mechanism can be used for the address allocation
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

18. Adaptive Block Addressing
March 2006
Adaptive Block Addressing
Stage 1: Association
[children#][children#]=[8][6] A
resv’ed: [beg,end]=[0,9000] branch1: [beg,end]=[9001,41000] branch2: [beg,end]=[41001,65000]
Stage 2: Children number collection
[5][2]
[5] B J
[9001,13000] [13001,33000] [33001,41000]
[41001,45000] [45001,65000]
Stage 3: Address assignment
An adaptive tree (AT) is formed.
Additional addresses are reserved.
[1][2][1]
[3][1] C H
[1] K
[13001,17000] [17001,21000] [21001,29000] [29001,33000]
[45001,49000] [49001,61000] [61001,65000]
[33001,37000] [37001,41000]
[0]
[37001,41000]
[0] D E G
[0] I L O
[1][1]
[61001,65000]
[0]
[1]
[29001,33000]
[49001,53000] [53001,57000] [57001,61000]
[17001,21000]
[21001,25000] [25001,29000] F M N
[0]
[0]
[0]
[25001,29000]
[57001,61000]
[53001,57000]
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

19. Guesses on Adaptive Block Addressing
March 2006
Guesses on Adaptive Block Addressing
Time for the association stage can be long.
Until association, the node cannot have his short address.
It did not solve the “running out of address” problem
Once a block is assigned to a branch, the block of the addresses is wasted until all the blocked addresses are allocated to the devices associated to that branch.
When new device is associated directly with PNC, a new block of addresses must be allocated, and this causes another waste.
Address allocation time can be long.
When a new device is associated with the node F, it does not have any address to allocate.
It has to wait until new address is assigned from the PNC
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

20. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
PNC A
[0, 1]
[1, 4]
[1, 2] B C
[1, 3] D
Devices B, C and D hear the beacon of A (PNC) and send Association Request Command.
Since A is PNC, PNC allocates the Short addresses to devices B,C,D directly.
If other device than PNC allocates short Address, it is possible that same address could be allocated to different devices.
To avoid this problem, LAA (LastAddressAssigned) field has been added.
The last address assigned at this point is 4, and the PNC sends this information to other devices using his beacon payload. To let B, C, and C know about this.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

21. Efficient Real-Time Address Assignment
March 2006
PNC A
[0, 1]
Beacon Update Request Command
[1, 4]
[1, 2] B C
[1, 3] D E
[2, 5]
Now, a new device E is on. As soon as he hears the beacon of B, it requests association.
Since B knows that the last address assigned is 4, B assigns the short address 5 to E and notifies the PNC of the new value of the LAA field through BeaconUpdateCommamd.
As soon as PNC receives this information, it modifies his beacon payload and send the modified beacon.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

22. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
PNC A
[0, 1]
Beacon Update Request Command
[1, 4]
[1, 2]
[1, 3] B C D E
[2, 5] F
When F associates, B assigns address 6 to F and sends the number 6 as the LAA (Last Address Assigned) to A.
Again, when A receives this command, it send his beacon after changing his beacon payload.
Because of the beacon payload, E and F knows the LAA.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

23. Efficient Real-Time Address Assignment
March 2006
PNC A
[0, 1]
Beacon Update Request Command
[1, 4]
[1, 2]
[1, 3] B C D
Beacon Update Request Command E
[2, 5]
[2, 6] H I F J
When J associates with F, F assigns address 7 to J and sends the number 7 as the LAA (Last Address Assigned) to B, and B sends this information to A.
Again, when A receives this command, it send his beacon after changing his beacon payload, and every device knows the LAA.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

24. Efficient Real-Time Address Assignment
March 2006
PNC
Beacon Update Request Command A
Beacon Update Request Command
[1, 2] C D
[1, 4] B
[1, 3]
[2, 5]
[2, 5] I E
Overlapped address assigned in real-time
A possible problem
When E and I associate, respectively, with B and D simultaneously, the same address may be assigned to tow different devices.
Solution
When this happens, the PNC sends Address Reassignment Command to the later arriving device
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

25. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
Beacon Update Response Command
PNC A
[1, 2] B C D
[1, 4]
[1, 3]
[2, 5]
[2, 5] I E
Overlapped address assigned in real-time
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

26. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
PNC A
Address Reassign Command
[1, 4]
Address Reassign Command
[1, 2] B C D
[1, 3]
[2, 6]
[2, 5] I E
Address Confliction resolved.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

27. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
PNC A
Beacon Update Request Command
Beacon Update Request Command
Beacon Update Response Command
Address Reassign Command B C D I E G
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

28. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
PNC
Beacon Update Request Command A
Beacon Update Request Command B G D
Beacon Update Request Command F I C E H
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

29. Efficient Real-Time Address Assignment
March 2006
Efficient Real-Time Address Assignment
PNC A
Beacon Update Request Command
Beacon Update Request Command
Address
Reassign B C D
Beacon Update Request Command
Beacon Update Request Command
Beacon Update Request Command
Beacon update Response command
Address
Reassign H G
Beacon Update Request Command E F
Beacon Update Request Command
Beacon update Response command
Beacon Update Request Command
Address
Reassign
Address
Reassign I J K
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

30. New Beacon Payload and Update Commands
March 2006
Octet:2 1
4/10 2
Var.
Frame
Control
Sequence
number
Addressing
Fields
Superframe
Specification
GTS
Field
Pending
Address
Beacon
Payload
FCS
MHR
MAC payload
MFR
Octets: 23 1 2
MHR Fields
Command
Frame Identifier
LAA
New Short Address
< LAA + Depth Info + BOPLength + BTTS >
<Beacon Update Request Command>
octets: 23 1
MHR fields
Command
Frame Identifier
LAA: LastAddressAssigned
BTTS: BeaconTxTimeSlot
< Beacon update Response Command >
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

31. Features of the Proposed Addressing Scheme
March 2006
Features of the Proposed Addressing Scheme
Pros
Allocates short addresses in real-time.
It is a decentralized addressing scheme combined with central PNC.
“Running out of addresses” problem is completely solved.
Network diameter not necessarily fixed.
Cons
New control commands must be added: Address Request, Address Response, Beacon Update, Address Reassign
Some delays occur in the Association process
Increased data processing in the PNC
Address reuse mechanism needs to be addressed.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

32. Conclusions and Discussions
March 2006
Mesh network requires a lot of problems to be solved
Beacon conflicts and Data Conflicts
Short Address allocations
Hidden and Exposed Node Problems
Delay-Sensitive Applications
Power-Saving Mechanism
Proposed a solution of avoiding beacon conflict by
Beacon scheduling
Proposed a solution of efficient address assignment
Address allocated in real-time by using LAA field.
Solved “Running out of address space” problem.
Proposed an architecture for WPAN Mesh which reflects the real service scenarios.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom

33. Acknowledgment This work has been supported by HNRC of IITA.
March 2006
Acknowledgment
This work has been supported by HNRC of IITA.
Ho-In Jeon, Kyung-Won University, Yongsik Shin, SKTelecom