TDMA for WiFi for links in unlicensed bands

NETSHe Lab has tested own firmware and wireless stack extensions with real link in 450MHz band with Doodle Labs DL435-30 (http://www.doodlelabs.com/products/radio-transceivers/sub-ghz-range/420-...) radios.

The link is the real city link in 422,5MHz with distance around 100 meters but with many objects in a Fresnel zone, very nosed environment (car alarm systems, portable radios) and with omnidirectional antennas. The channel width in the 5MHz was used for the link. First device was configured as an Access Point and second was configured as Client (simple CSMA/CA mode).
DL435-30 cards are 802.11bg compatible (supported with ath5k driver) with down frequency converter cards.

NETSHe powered firmware with TDMA extension is used for tests.
Tests scenario was included:
- throughput and link stability evaluation in CSMA/CA modes for channel widths in 5/10/20MHz;
- throughput and link stability evaluation in TDMA modes for channel widths in 5/10/20MHz;

The link got much better throughput in TDMA mode rather than in CSMA/CA and was updated to TDMA (TDMA BS/CPE mode with individual acknowledgements is used).
The reasons to better throughput for TDMA modes are:
- collisionless access method (no internal collisions between link nodes);
- frame aggregation in TDMA modes;
- frames more than 3kB in TDMA modes.

The throughput results can be found at http://www.netshe.ru/files/doc/en/test_results_dl_02042015.pdf