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: [Mesh networking for low-rate systems] Date Submitted: [May, 2006] Source: [Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille] Company [THALES Communications] Address [THALES Communications, 146 boulevard de Valmy, 92704 Colombes, France] E−Mail: [arnaud.tonnerre@fr.thalesgroup.com, serge.hethuin@fr.thalesgroup.com, isabelle.bucaille@fr.thalesgroup.com] Re: [802.15.5.] Abstract: [Mesh networking for low-rate systems] Purpose: [To promote discussion in 802.15.5] 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. Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

2. Mesh networkingfor low-rate systems Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille THALES Communications France Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

3. Objectives • To present a Mesh design for low-rate systems based on 802.15.4 • To make recommendations on Centralized Mesh networking • To provide simulation results related to Mesh architectures The work has been partly supported by the European Commission R&D Integrated Project PULSERS, IST-FP6-506897 and IST-FP6-027142 Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

4. Contents • Centralized Mesh networking • Routing protocol: 2-LMR • Multi-piconet architecture • Simulation results Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

5. Centralized Mesh networking Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

6. Scheduling Tree Mesh network Centralized Mesh networking • The coordinator handles synchronization and scheduling • 2-step formation: • Scheduling Tree construction • Used for control frame transmissions • Meshing the topology based on the Scheduling Tree Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

7. Control portion Control portion Data portion Data portion Beacon period Request period Topo mgmt period Beacon slot CAP CAP CFP CFP Inactive Inactive Mesh superframe structure • Superframe structure based on 802.15.4 • Control portion length is increased • Beacon period • Request period • Topology Management period Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

8. Mesh superframe structure • Fine structure • Superframe is divided equally into slots • Use of Minislots in the Control portion • Provides flexibility: adaptation to different frame durations • Guaranteed Time MiniSlot (GTMS) can be introduced in CFP • Particularly interesting for short data frames such as ranging signaling • Ranging is a major function of 802.15.4a Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

9. Minislot Slot B Tree Level 0 B B B B Tree Level 1 Beacon period Mesh superframe structure • Beacon period • The beacons are relayed along the Scheduling Tree • The beacon-frame length shall be minimized • Dropping overheads introduced by beacon relaying • Reducing address size to 8 bits (mesh addresses) • Beacon alignment procedure • To avoid interference between close neighbors • Algorithm based on the tree level (number of hops to reach the coordinator) Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

10. Coordinator Tree Level 0 A Tree Level 1 B H Tree Level 2 C F I GTS request frames Tree Level 3 D E G J K Mesh superframe structure • Request period • Request period is a set of GTS dedicated to allocation demands • Transmission from the leaves to the coordinator GTS requests require guaranteed access in the superframe Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

11. GTS request sent in CAP Max delay = 7 s GTS request sent in a GTS Max delay = 35 ms Mesh superframe structure • Request period • Peak of delay due to request/grant allocation • Behavior of the MAC in overloaded networks • Simulations: 2 types of request transmission • In CAP of data portion • In guaranteed time slot of the control portion Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

12. Mesh superframe structure • Topology Management period • Two types of message are sent in this period • Link State procedure • Allows the coordinator to build the Scheduling Tree • Periodic transmission ofHello frames from every associated device • Hello frames transport the 2-hop neighborhood of the originator • Scheduling Tree update • Keep informed the devices of the Tree structure Hello frames (Link State procedure) Scheduling Tree Update (STU) frames Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

13. 2-Level Mesh Routing protocol(2-LMR) Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

14. 2-LMR protocol • 2-LMR protocol provides routing based on Link States • Reuse of link state procedure dedicated to tree construction • No additional messages is required • Efficient pro-active routing protocol • Packets can be routed using 2 types of path: • Tree route based on the scheduling tree • Local route defined by the local link states Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

15. 2-LMR protocol • Local Route repair • Starts when a non-tree link is broken • Detected thanks to the Link State procedure • A new route is built based on updated link states • Repaired route is inserted in the local routing tables Coordinator A Source B H Destination C F I Hello frame D E G J K Initial route Repaired route Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

16. 2-LMR protocol • Tree Route repair • Starts when a tree link is broken • Information transferred to the coordinator (Link State procedure) • The coordinator builds a new Scheduling Tree • The structure is broadcast using Scheduling Tree Update (STU) frames Coordinator A Source B H Destination C F I STU frame D E G J K Initial route Repaired route Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

17. Multi-piconet Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

18. Multi-piconet • Simultaneous operating piconet (SOP) • Mandatory use of CDMA • Optional use of FDMA if several frequency bands are available • Use of Inactive period is possible in some cases • Duty cycle should be very low • The inactive periods should be large enough Lower complexity Requires coordination between SOP Involves a significant loss of bandwidth Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

19. Multi-piconet • Communication between piconets • Clusters (or piconets) are structured hierarchically • Primary piconet is the parent cluster of every cluster in the network • Parent / Child structure • Border nodes are coordinators of child clusters (Cluster Heads) • Management of the border nodes is touchy Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

20. Simulations Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

21. Simulations • Centralized Mesh architecture • Scheduling Tree centralized on the coordinator • Mesh network based on the Tree Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

22. Simulations • Centralized Mesh architecture • End-to-end delay is a significant “figure of merit” • Traffic behavior depends on the selected access protocol • Grasp the impact of relaying Average end-to-end delay as a function of the number of relays in CFP Average end-to-end delay as a function of the number of relays in CAP Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

23. Cluster Backbone Simulations • Clusterized Mesh architecture • Dedicated to high density environment • Structure: • A Backbone, based on a Centralized Mesh topology • Clusters in single-hop topology Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

24. Simulations • Clusterized Mesh architecture • Simulation results Average end-to-end delay as a function of the number of relays Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

25. Simulations • Cluster Tree architecture • Extend range in a low density environment • Structure: • Set of clusters representing a tree • Each cluster is a Centralized Mesh topology Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

26. Simulations • Cluster Tree architecture • Simulation results Average end-to-end delay as a function of the number of relays Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

27. Conclusion • Division of Slots into Minislots for flexibility • In Control portions • In the CFP of Data portions • GTS request requires guaranteed access in the superframe • 2-LMR routing protocol • Efficient pro-active protocol • Without additional control overload • Use of CDMA for multi-piconet access Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille

28. References • PULSERS D3a2, “Candidate architecture for HDR and LDR-LT operational modes”, December 2004. • PULSERS D51b, “Definition of new concepts/architectures for UWB MAC and networking [HDR and LDR-LT]”, March 2005. • PULSERS D3a3, “Selection of architecture for HDR and LDR-LT operational modes including simulation results”, June 2005. Arnaud Tonnerre, Serge Héthuin, Isabelle Bucaille