A Wifi interface connects the RPX-100 with the LAN for remote operation, debugging and programming. The software id written C++ using liquid-dsp libraries. The concpet of the WRAN software uses the IEEE 802.22 frame structure for prototyping to make use of super frames and preambles for cognitive channel management, which allows a dynamic resource allocation between base stations, but also between multiple users at one base station.

Orthogonal Frequency Division Multiple Access (OFDMA) is used in the upper layers, as Modulation techniques QPSK, 16-QAM and 64-QAM is supported.

The software will support a connection-oriented MAC layer with cognitive functionality for dynamic and adaptive scheduling and management of coexistence of base stations in the same time-frequency domain (superframes).

Goals of the WRAN project:

  • Evaluate and select appropriate wireless communication protocol similar to existing Wireless LAN protocols but suitable for the VHF and UHF bands.

  • Define a new transmission protocol for wideband data communication for efficient use of a 2Mhz spectrum in the 6m or 70cm band and suitable as “last mile” connection for existing backbone networks.

  • Software development and implementation of the transmission protocol on a prototype SRD hardware for a base station and end users devices.

  • Test and evaluation the new transmission protocol in lab- and field environments on selected Radio Amateur Relay locations in Austria.

  • Benchmark how reliability and scalability such a new transmission protocol can be operated in the HF, VHF and UHF band.

  • Provide a kit for Radio Amateurs to build and develop their own base stations and end-user devices for the new transmission protocol.

Project Milestones:

  • The Institute of Telecommunications of TU Wien has been granted a test permit by the Federal Ministry of Agriculture, Regions and Tourism to test and operate the new transmission scheme at a 2 MHz Band from 52-54 MHz at 2 selected location in Austria. The permit has been extended for one year till May 2022.

  • The IEEE 802.22 frame structure has been selected for prototyping the software and hardware to make use of super frames and preambles for cognitive channel management, which allows a dynamic resource allocation between base stations, but also between multiple users at one base station.

  • The new hardware and software stack has been successfully tested using the Raspberry Compute Module CM4 in combination with LimeSDR mini. The advantages are a small form factor, performance and the 12V supply Voltage for mobile operation.

  • A Radio Frontend has been developed and tested for VHF and UHF (6m, 2m and 70cm Band) with a design to fit as hat-board to the Raspberry CM4 IO board and operates with 12V supply voltage. The Output power can be regulated via software between 0 - 10W.