Antenna

The antenna-part of the software-radio has the structure as shown in fig. @Antenna-blowup: Common/Driver/HW/Server@ Their respective functions are as follows:

• Common is the interface towards the signal processing part
• Driver implements a certain hardware or simulation
• Hardware or Simulation the actual transmission system

Common

The interface of the antenna offers the following parameters to the signal-processing part:

• DMA-region a place where the received samples are written to and the samples to be sent are read from
• RF-parameters frequency, amplitude and other config-parameters
• Timing an function is available that tells about the actual timing of the RX/TX part

Driver

This is the implementation of a certain way to transmit and receive samples. It has to take care about all initialisations and correct handling of all exceptions. The following drivers are functional:

• RF interfaces the old, STMicroelectronics based RF-system
• ICS interfaces the new, ICS-based RF-system that is capable of MIMO-transmission
• Simul for simulations of the RF-system
• Simul_ics for simulations of the ICS-system
• Emul does a simple copy of the data to be transmitted to the next slot
• NOP does nothing, for debugging purposes

Hardware or Simulation

The final part of the software-radio defines the channel. The Emul driver, for example, implements a flat single-tap channel with no noise. The Simul drivers need a channel-server that takes multiple radios together, mixes their signal, and sends back the calculated signal.

The most interesting parts are the RF and ICS hardware, because they offer a real channel to test the transmission with.

Hardware

In the following table you can find a comparison of the two hardware-systems available.

	RF	ICS
Max. number of antennas	1	4
Frequency [GHz]	1.9	2.4-2.48
Bandwith [MHz]	3.8	1
Resolution	12	14

Simulation

In simulation-mode, a channel-server accepts connections from different radios, as can be seen in fig. @channel-server with two radios@. The channel-server can simulate multi-tap channels and add gaussian noise to the transmitted signals. This allows for easy simulation of real-world signals, before taking the modules on the air.