testbed

Software Architecture

Testbed

Current configuration is based on 23 nodes deployed across two buildings, implementing two local indoor wireless mesh networks interconnected by an outdoor WiFi point-to-multipoint wireless link. Mesh routers build and maintain the multi-hop wireless back-haul and provide end-users with a standard 802.11 Access Point. Internet connectivity is delivered by a dedicated mesh routers equipped with an high bandwidth connection to the Internet backbone. A third tier providing Internet connectivity by means of a Point-to-Multipoint wireless technology (e.g. WiMAX, WiFi, or UMTS) is also supported.

Mesh routers are built exploiting three different types of processor boards:

• PCEngines ALIX 2C2, 500MHz x86 CPU, 256MB of RAM

• PCEngines WRAP 1E, 233MHz x86 CPU, 128MB of RAM

• Gateworks Cambria GW2358-4, 667MHz ARM CPU, 128MB of RAM

Operating system and application are stored on a 1 GB Compact Flash card for the PCEngines processor boards and on the 32 MB embedded flash memory for the Gateworks boards (in this case a 4GB Compact Flash is used to provided additional storage. It is worth noting that the full WING firmware including development and testing tools (traffic generator, loggers, etc.) requires 16MB of storage space. A stripped down version of the firmware without development and testing tools requires less than 4MB of storage.

Connectivity is provided by 2 Ethernet channels, 2/4 miniPCI slots (PCEngines/Gateworks) and one serial port. PCEngines ALIX/WRAP boards are equipped with two Mikrotik R52 WiFi IEEE 802.11a/b/g cards based on the Atheros AR2412 chipset. Gateworks boards are equipped with either two Ubiquiti SR71-A WiFi IEEE 802.11a/b/g/n cards based on the Atheros AR9160 chipset or two Mikrotik R52 WiFi IEEE 802.11a/b/g cards based on the Atheros AR2412 chipset.

On both the PCEngines and the Gateworks platform both interfaces builds and maintains the multi-hop wireless backhaul. One interface can be configured either in either Client or in Master mode. The former configuration allows the node to share an already available WiFi connection with the entire WMN while the latter configuration is used to provide a standard IEEE 802.11 Access Point. Single interface setups are also supported, however, in this case the same wireless interface manages the multi-hop wireless backhaul and provides access the end-users. Dual and single NIC nodes can coexists in the same network.