Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 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, 139-701, Korea] Voice:[+82-2-943-7607], FAX: [+82-2-943-7607], E-Mail:[rhee@ieee.org] Re: [Call for Proposal: IEEE P802.15-5/0071] 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 802.15 TG5] Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15. Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

2. 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] • 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] Mesh Link Obstacle Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

5. MPA MAC: Hierarchical Approach [Hiertz05] • Superframe equally slotted • Medium Access Slots (MAS) • Mesh WPAN devices serve .15.3 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 • 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… • 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 • Mesh DEVi 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 • 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 • 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) • DTP length: 100 MAS • α1 = α2 = α3 = 0.5 Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

12. 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 • α1 = 0.5 • α2 = 0.66 • α1 = 0.5 • α2 = 0.75 Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

14. 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 Rhee, Lee, Lee, Jeon and Choi <KWU/ETRI>

16. 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 • 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. Our Proof Shows that • All devices converge to a unique equilibrium point T*, regardless of • Number of devices • The values of αiand 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 • 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. References [Shao06] Shao et al, “WPAN Mesh Networking Merged Proposal,” IEEE P802.15-06/0174, March 2006 [Hiertz05] Hiertz et al, “Mesh PAN Alliance (MPA) and .15.3 integration,” IEEE P802.15-05/0670, 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>