Impact of Node Heterogeneity in ZigBee Mesh Network Routing

1. Impact of Node Heterogeneity in ZigBee Mesh Network Routing Nia-Chiang Liang, Ping-Chieh Chen, Tony Sun, Guang Yang, Ling-Jyh Chen, and Mario Gerla

2. Outline • Motivation • Background • Evaluation • Conclusion

3. Motivation • In most ZigBee usage scenario • Some ZigBee devices will be less powerful with regards to the rest of the network. • Ubiquitous access to/from some mobile ZigBee devices are required. • Accommodating mobility of heterogeneous devices is of general interest • Heterogeneity distinguishes ZigBee networks from other ad-hoc networks • Better understanding of heterogeneity support can facilitate further improvement, usage, and deployment

4. Background - ZigBee • Based on the Low Power, Low Rate IEEE 802.15.4 Standard • ZigBee is the network and application specification developed by the ZigBee alliance. • Back by 150+ member companies and numerous adopters • Released June 2005

5. ZigBee Coordinator ZigBee Router ZigBee End Device Background- ZigBee • Three device types • Coordinator: FFD • Routers: FFD • End devices: RFD or FFD • End devices with limited functionality to control cost • Can only communicate to parent router • Rely on their parent router for routing functionality • ZigBee node has two addresses • 16-bit network address • 64-bit MAC address

6. ZigBee Mesh Address • Dynamic address assignment • New network address acquired when a node join a new parent node • i.e. moved out of the range of its original parent node, parent node moved away or failed, and etc. • Maintains a hierarchal addressing structure • Each parent assigns an address “space” for child routers so they can allocate that space for their descendants 0x0300 0x0000 0x0310 Child nodes joins parents through Join and Associate Mechanisms 0x0311 0x0100 0x0312 0x0200 0x0314 0x0313

7. ZigBee Mesh Routing • Routing “similar” to AODV routing • RREQ (Route Request), RREP (Route Reply), and RERR (Route Error) • Additional modification aim to simply network design • Intermediate nodes does not reply to route requests, • Route entry doesn’t time out, no periodic hello messages, and etc.

8. Routing in ZigBee Network • Different from traditional 802.11b based MANET routing • Not all participating nodes are routing capable • ZigBee copes with low power devices • We implement the ZigBee evaluation framework in NS-2 simulator for the below purposes • To gain a better understanding of how well ZigBee performs in mobile pervasive application environment • Evaluate application deployment scenarios and derive performance expectation, deployment guidelines, and etc.

9. Evaluation • We develop our own ZigBee routing module in NS-2 • Our simulation scenario is set to closely mimic the settings of a household/factory deployment • Nodes initially aligned in an equally spaced grid • Nodes move within the set topology according to random waypoint model with speed of 1m/s • All results averaged across 50 independent trials • Percentage of ZigBee end devices to ZigBee routers vary while mobile nodes are chosen randomly

10. Evaluation cont.

11. ZigBee device acting as sender 20% mobile nodes router end device

12. ZigBee device as receiver 20% mobile nodes router end device

13. ZigBee device acting as sender 50% mobile nodes router end device

14. ZigBee router as receiver 50% mobile nodes router end device

15. Conclusion • ZigBee networks are heterogeneous in nature and differ from regular MANETs • We developed the first NS-2 ZigBee simulation module to simulate the behavior of ZigBee networks • In almost all scenarios simulated, delivery ratio decreases with increased heterogeneity and increased mobility • ZigBee end devices are not suitable to be receivers since they suffer greatly from mobility

16. Thank You!