1. July 2006
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Self-managed Channel Time Allocation for WPAN Mesh Networks]
Date Submitted: [12 July, 2006]
Source: [Seung Hyong Rhee, Wangjong Lee, Hyukjoon Lee, Young Ae Jeon, Sang Sung Choi]
Company [Kwangwoon University / Electronics & Telecommunications Research Institute]
Address [447-1 Wolgye-dong, Nowon-gu, Seoul, , Korea]
Voice:[ ], FAX: [ ],
Re: [Call for Proposal: IEEE P /0071]
Abstract: [This document suggests to adopt a self-managed and self-stabilizing mechanism that achieves a fair channel time allocation and admission control in WPAN mesh networks. It also provides a distributed means for service differentiation.]
Purpose: [Providing technical contributions to IEEE TG5]
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
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

2. Self-managed Channel Time Allocation for WPAN Mesh Networks
July 2006
Self-managed Channel Time Allocation for WPAN Mesh Networks
July 2006
KWU/ETRI
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

3. 15.5 Scope: High-Rate Mesh Architecture [Shao06]
July 2006
15.5 Scope: High-Rate Mesh Architecture [Shao06]
Agreements
Every mesh-capable device has to beacon
Distributed channel time sharing between mesh devices
Mutual coordination of neighbor’s channel time allocation
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

4. Example: SOP Support in 15.3 [Hiertz05]
July 2006
Example: SOP Support in 15.3 [Hiertz05]
Mesh Link
Obstacle
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

5. MPA MAC: Hierarchical Approach [Hiertz05]
July 2006
MPA MAC: Hierarchical Approach [Hiertz05]
Superframe equally slotted
Medium Access Slots (MAS)
Mesh WPAN devices serve devices as PNC
Reserved MAS for piconet traffic
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

6. Motivation No central controller for the mesh devices
July 2006
Motivation
No central controller for the mesh devices
Among the mesh devices, we still need
Fair channel time allocation
Decentralized admission control
Service differentiation
How can it be done in a distributed and self-managed way?
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

7. Problems Could be Hard…
July 2006
Problems Could be Hard…
Mesh devices will be on the move
They may join and leave the network frequently
It makes the resource allocation and admission control harder
Multimedia traffic transmissions
They usually have minimum bandwidth requirements
Sometimes exist maximum requirements
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

8. Notation: Reservations among Mesh Devices
July 2006
Notation: Reservations among Mesh Devices
Mesh DEV i reserves duration Ti of MAS
Their min/max requirements (mi / Mi) are given
Reservation vector T = (T1 ,…,TK ) is feasible if C
beacon
period
reserved for DTP
(data transmit period)
CAP
(inactive period) T1 T2
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

9. Algorithm 1: Computing the Share
July 2006
Algorithm 1: Computing the Share
Mesh DEVs take turns to make reservations
DEV i , at its turn,
Computes T1
Computes T2
Computes Tn
▪ ▪ ▪ ▪ T1 T2 Tn
DEV1 beacon
DEV2 beacon
DEVn beacon
beacon period
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

10. Algorithm 2: Admission Control
July 2006
Algorithm 2: Admission Control
Mesh DEV i makes a self-decision for joining the mesh network
At the end of BP,
read m1
read m2
read mn
decision
▪ ▪ ▪ ▪ m1 m2 mn
DEV1 beacon
DEV2 beacon
DEVn beacon
beacon period
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

11. Example: Fairness & Convergence (1)
July 2006
Example: Fairness & Convergence (1)
DTP length: 100 MAS
α1 = α2 = α3 = 0.5
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

12. Example: Fairness & Convergence (2)
July 2006
Example: Fairness & Convergence (2)
DTP length: 100 MAS
α1 = α2 = α3 = 0.25
DTP length: 100 MAS
α1 = α2 = α3 = 0.75
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

13. Example: Service Differentiation
July 2006
Example: Service Differentiation
α1 = 0.5
α2 = 0.66
α1 = 0.5
α2 = 0.75
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

14. Example: Minimum Requirements
July 2006
Example: Minimum Requirements
Min requirement of DEV1: 30 MAS
α1 = α2 = α3 = 0.5
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

15. Example: Join/Leave of DEVs
July 2006
Example: Join/Leave of DEVs
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

16. Analytical Modeling [Rhee06]
July 2006
Analytical Modeling [Rhee06]
Our resource allocation mechanism can be modeled as follows:
where Ui is a strictly concave real function such that
Given C and T = (T1 ,…,TK ), this is a distributed optimization problem among the devices
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

17. Gauss-Seidel Type Iteration
July 2006
Gauss-Seidel Type Iteration
We adopt the Gauss-Seidel type iteration
Only one component of T is updated at a time
The most recent information is available to the devices
Let T(t) = (T1(t), …, TK(t)), our iterative equation is
T(t+1) = F(T(t)), t = 0,1,…
In our implementation,
T(t) and T(t+1) are different only in their ith element
DEV obtains info on T(t) from previous beacons
DEVs are asynchronous: no pre-specified order among them
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

18. July 2006
Our Proof Shows that
All devices converge to a unique equilibrium point T*, regardless of
Number of devices
The values of αi and min/max requirements [mi , Mi]
Their reservations converge to T*
Always within a finite time
The amount of allocation at the equilibrium is
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

19. Conclusion Self-managed channel-time allocation for mesh WPANs
July 2006
Conclusion
Self-managed channel-time allocation for mesh WPANs
Fair allocation without a controller
Decentralized admission control
Service differentiation
Analytical modeling proves
Self-stabilizing property of our algorithm
Fair and differentiated allocation
Correctness of the simulation results
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

20. July 2006
References
[Shao06] Shao et al, “WPAN Mesh Networking Merged Proposal,” IEEE P /0174, March 2006
[Hiertz05] Hiertz et al, “Mesh PAN Alliance (MPA) and integration,” IEEE P /0670, Nov. 2005
[Rhee06] Rhee et al, “Self-managed multiple access control for the distributed wireless PANs,” submitted to 8th Int. Symposium on Stabilization, Safety, and Security of Distributed Systems
Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>