1. September 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Efficient Address Assignment for Mesh Nodes in Real-Time]
Date Submitted: [15 July, 2005]
Source: [Ho-In Jeon (1), Sung-Hoon Jeong (2), Yong-Bae Kim (2), Bum-Joo Kim (2)]
Company: [Dept. Electronic Engineering, Kyung-Won University(KWU) (1), LeiiTech Inc. (2)]
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 partly by HNRC of IITA.]
Abstract: [This document proposes an efficient way of assigning short addresses to mesh nodes in real- time without address conflicts.]
Purpose: [Final Proposal for the IEEE a 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

2. Efficient Real-Time Address Assignments for Mesh Nodes
September 2005
Efficient Real-Time Address Assignments for Mesh Nodes
Ho-In Jeon
Kyung-Won University, HNRC of IITA
Republic of Korea
Ho-In Jeon, Kyung-Won University

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
September 2005
Contents
Introduction
Definition of mesh networks
Issues of mesh networks
Beacon Scheduling
Short Address Allocation
RTS/CTS for Collision Avoidance
Routing
Power-Saving Operation Mode
A Scenario for the operation of Mesh Network
Proposed Address Assignment Scheme
Features of the proposed Scheme
Conclusion
Ho-In Jeon, Kyung-Won University
<author>, <company>

4. Issues of Mesh Networks
<month year>
doc.: IEEE <doc#>
September 2005
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
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 for Data Transmission
Deterioration of Data Throughput
Overall Delay
Exposed Node Problem
Ho-In Jeon, Kyung-Won University
<author>, <company>

5. U-Home with Mesh Network
September 2005
U-Home with Mesh Network
Utility Room
Washer
Gas
Meter PC
Mesh
Mesh
Room #3
VPhone
Gas
Oven
PDA
DTV
Room #2
Bath-
room
Refrig.
DTV PC
Microwave
Oven
Oven
Kitchen
STB
DCam.
: IEEE1394 or UWB Connectivity
: IEEE802.11x, 15.3, ZigBee/15.4, 15.5 Mesh
Mesh
Mesh
VPhone
Living Room
Door
Phone
DTV
ZigBee/15.4
802.11a/g/n/e,
IEEE
Mesh PNC
Meter
Reader
PVR
Room #1 PC
Power
Meter
DCam.
Room #4
DTV
VDSL MODEM
DAM
PDA
Water
Meter
PVR
Phone
Jack
HS/ MMRG
Printer
Phone
Jack
AP or PNC
PDA
DCam.
Cable, Satellite, Terrestrial
FTTH
DSLAM
ONU
Internet
Ho-In Jeon, Kyung-Won University

6. Environment Management with Mesh
September 2005
Sensor Gateway 1 2 3 4
N-2
N-1 N
Management Center
20 Km
A scenario in which the device 1 wishes to send its sensed data to device N which is the sensor gateway located 20 Km apart.
Assumptions
The RF range of each device is assumed to be 20m.
Multi-hop topology has been used for the propagation of data
Each device is assumed to use beacon to reduce power consumption.
Device 2 listens to the beacon transmitted by device 1 and decides to associate with it. Device 2 determines its beacon transmitting time slot.
Device 1 is 40m apart from device 3 which implies that device 3 cannot listen to device 1.
Ho-In Jeon, Kyung-Won University

7. A Scenario for Mesh Network Operations
September 2005
A Scenario for Mesh Network Operations 4 9 1 2 6 5 2 9 1 6
PNC 3 4 8 7
Issues to be resolved
Association and Reassociation Procedure
Beacon Scheduling
Short Address Allocations
Creation and Update of Neighborhood Table
Ho-In Jeon, Kyung-Won University

8. PNC Formation of the Mesh
September 2005
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

9. Joining of Device 2 to the Mesh
September 2005
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

10. Association Relations and Beacon Tx
September 2005
Association Relations and Beacon Tx
Solid blue line represents the Parent-Child relations based on associations.
Red line represents directly reachable.
Every mesh device transmits beacon during the BOP (Beacon-Only Period).
Beacon scheduling has been applied. 2 1
PNC 3
Superframe
Inactive Period
Active Period
BOP
CAP 1 2 3
Ho-In Jeon, Kyung-Won University

11. Association and Direct Links Relations
September 2005
Association and Direct Links Relations 4 9 1 2 6 5 2 9 1 6
PNC 3 4 8 7
BOP
CAP 1 2 3 4 5 6 8 7 9
Ho-In Jeon, Kyung-Won University

12. Association and Direct Links Relations
September 2005
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

13. Short Address Allocations
September 2005
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

14. Efficient Real-Time Address Assignment
September 2005
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 Dev. 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

15. Efficient Real-Time Address Assignment
September 2005
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

16. Efficient Real-Time Address Assignment
September 2005
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

17. Efficient Real-Time Address Assignment
September 2005
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

18. Efficient Real-Time Address Assignment
September 2005
Efficient Real-Time Address Assignment
[0, 1]
PNC A
Beacon Update Request Command
[1, 2]
[1, 3] B C D
[1, 4]
[2, 6] H I
[2, 9] E
[2, 5] F
[2, 8]
[3, 7] J
The same procedure applies to the rest of the devices and every device knows the LAA.
Ho-In Jeon, Kyung-Won University

19. Efficient Real-Time Address Assignment
September 2005
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
Real-Time overlapped address assignment.
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

20. Efficient Real-Time Address Assignment
September 2005
PNC
Beacon Update Request Command A
Beacon Update Request Command
Beacon Update Response Command
[1, 2] C D
[1, 4] B
[1, 3]
[2, 5]
[2, 5] I E
Real-Time overlapped address assignment.
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

21. Efficient Real-Time Address Assignment
September 2005
PNC
Beacon Update Request Command A
Beacon Update Request Command
Address Reassign Command
[1, 2] C D
[1, 4] B
[1, 3]
Address Reassign Command
[2, 5] I E
[2, 6]
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

22. Efficient Real-Time Address Assignment
September 2005
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

23. Efficient Real-Time Address Assignment
September 2005
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

24. Efficient Real-Time Address Assignment
September 2005
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

25. Efficient Real-Time Address Assignment
September 2005 B C
PNC
Beacon
Association Request
Association Response : Assign the short address 2 to B.
Beacon
Set the value of LAA
(LastAddressAssigned) to 2.
Association Request
Association Response : Assign the short address 3 to C.
Beacon Update Request Command
PNC updates his LAA to 3
The new updated LAA value is 3.
Beacon Transmitted.
Ho-In Jeon, Kyung-Won University

26. New Beacon Payload and Update Commands
September 2005
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

27. New Beacon Payload and Update Commands
September 2005
octets: 23 1 2
MHR fields
Command
Frame Identifier
Short Address assigned by PNC
<Address Reassign Command>
Command Identifier
Command Name
0 x 01
Association request
0 x 02
Association response
0 x 03
Disassociation notification
0 x 04
Data request
0 x 05
PAN ID conflict notification
0 x 06
Orphan notification
0 x 07
Beacon request
0 x 08
Coordinator realignment
0 x 09
GTS request
0 x 10
BOP update request
0 x 11
BOP update response
0 x 12
Address reassign
<Command Frames>
Ho-In Jeon, Kyung-Won University

28. Features of the Proposed Addressing Scheme
September 2005
Features of the Proposed Addressing Scheme
Pros
Allocates short addresses in real-time.
It is a decentralized addressing scheme combined with.
“Running out of addresses” problem is 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

29. Conclusions and Discussions
September 2005
Mesh network requires a lot of problems to be solved
Beacon conflicts
Short Address allocations
Data Conflicts
Hidden 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 decentralized manner.
Address conflicts resolved by centralized control.
Solved “Running out of address space” problem
Ho-In Jeon, Kyung-Won University

30. Acknowledgment This work has been supported HNRC of IITA.
September 2005
Acknowledgment
This work has been supported HNRC of IITA.
Ho-In Jeon, Kyung-Won University