Wireless Mesh Networks Shyam Seshadri Zaheer Ahmed ECE 4605 Final Presentation

Context / Background EZ-Net DevKit Six wireless nodes Dynamic configuration - different topologies (mesh, cluster tree, linear, hybrid) Master node - network controller End node - No routing functionality

RN+ vs. RN- RN- Uses far less resources at expense of routing capabilities No routing table or route computation Based on hierarchical routing RN+ Capable of peer-to-peer on-demand routing Asseses best routing option based on prior handshakes Requests as well as responds to routing enquiries

Aims Configuring the network – static and dynamic Establish PC-Node communication Establish PC-PC communication Range testing Dynamic properties Healing properties RN+ vs. RN-

Initial Work: Network Setup Initial configuration Each node must be manually plugged into a PC through RS232 A specific topology and a specific node configuration is written When the network is up, nodes can be dynamically configured to different topologies

PC – Node Communication RSSI: Receiver Signal Strength Indicator

PC – PC Communication Connect a PC to each node using RS 232 cable Use inbuilt “Transparency” feature Like an Instant messenger Allows the PCs to communicate as if directly connected through the RS 232 Hence “Transparency” – the intermediate wireless network is transparent to the PCs

PC – PC Communication

Range testing Linear topology Nodes used: A B Brought nodes very close, then moved apart Fixed distance of 40m 60m

Dynamic Properties Linear topology with all six nodes Removed and replaced nodes one at a time Observed time taken for dataflow to begin again

Dynamic Properties 1 byte/sec 100 byte/sec B 2.05s C 0.2s D 1.1s E Constant queries are sent probing for the node to come back up

Hybrid 2 Network Diagram

Self-Healing Mechanism Hybrid 2 network – Node A : Node F Chooses route through node D to destination node F Remove node D 15s – Re-routes through C Remove node C 14s – Re-routes through B Re-initialize D and C Still uses route through B

Mesh Network Diagram

Self-Healing Mechanism II Mesh Network (add diag) Node A : Node D Remove B 15s – Re-route through C Re-initialize B No change in route taken Route updating done only when current route is disturbed

Self-Healing Mechanism

Hybrid 3 Network Diagram

RN+ vs. RN- I Hybrid 3 network – Node A : Node E Remove C 15s: Error messages Waiting for C to come back up 15s+: Time Out messages Route update never received C was the only RN+ node RN- nodes incapable of providing route updates

Cluster tree 2 Network Diagram

RN+ vs. RN- II Cluster tree 2 – Node A : Node F With B as RN- Route through C chosen C is an RN+ with a routing table With B as RN+ Few seconds taken initially to synchronize – errors seen on RSSI Route through B chosen

Setbacks Replacing the wireless antenna and re-configuring fixes problem of node not responding Random losses during RSSI testing Unable to run serial port scripts Unstable application software Fails to detect a connected node during some runs Restart of application necessary

More research? Further investigation into RN+ and RN- nodes Throughput tests Tests with RF obstacles

Summary Different networks set up Range – up to 60m Dynamic properties examined Study of Self-healing properties RN+ vs. RN-