A Network Testbed for Ad-Hoc Communications using Raspberry Pi and 802.11

Abstract

We have built a testbed ad-hoc wireless network to evaluate the AllNet ad-hoc networking protocol. The testbed currently consists of 4 Raspberry Pi Zero W embedded systems and a linux laptop, all using 802.11/WiFi ad-hoc (IBSS) mode. The embedded systems are placed in a line such that each is only able to reliably communicate with one system before it and one system after it in line.

The testbed displays phenomena that are observed in real life, including:

- greater delay to reach devices that are farther away

- variability in the round-trip time to each device

- the current version of the AllNet protocol (AllNet~3.2) successfully prioritizes messages. In particular, trace messages, which are sent with least priority, are rarely delivered if mainstream data traffic from the AllNet network is allowed onto the testbed.

- system connectivity varies over time, sometimes allowing direct links between systems that are normally unable to communicate

The paper includes practical considerations of testbed deployment using the Raspberry Pi, and an analysis of the performance of the AllNet protocol that is driving improvements in the design and implementation.