Software-Defined Radio Could Unify Wireless World

mjdroner writes "Technicians in Ireland are testing a device capable of skipping between incompatible wireless standards by tweaking its underlying code. The article states: 'The device can impersonate a multitude of different wireless devices since it uses reconfigurable software to carry out the tasks normally performed by static hardware. The technology promises to let future gadgets jump between frequencies and standards that currently conflict. A cellphone could, for example, automatically detect and jump to a much faster Wi-Fi network when in a local hotspot.'"

Comments

A plug for GNU Radio

[InterruptDescriptorT]

Since we're talking about Software Defined Radio, I urge everyone with an interest in the subject to look at the GNU Radio project. They have designed a front end board using generic cable TV tuners feeding an FPGA to perform some initial processing, such as decimation and filtering. The data is then transferred over USB to the host, whose software performs the demodulation and decoding. It's a fascinating project and a great stepping stone into the field.

To really get started on SDR, check out the Ten-Tec RX320D shortwave receiver. It outputs a 12 kHz-wide IF signal from the front end to an audio jack, which can then be fed to a PC soundcard. There are a number of packages that can take this data and demodulate it, including DREAM, an open source DRM (Digital Radio Mondiale) decoder which allows you to listen to the new digital shortwave transmission standard that many of the world's broadcasters are beginning to experiment with.

Here's the big deal

[TubeSteak]

The underlying technology has the potential to revolutionise wireless communications but has been difficult to test outside the laboratory until now as the majority of the radio spectrum has already been allocated. Licences are normally limited to a particular radio frequency and modulation but the one issued to CTVR permits a device to hop quickly between many different standards.

The CTVR trial will also test how easily frequencies can be dynamically allocated to different devices. One idea is for companies that own a licence to automatically "sublet" access depending on demand. The licence [to trial the software radio] means we will be the first research centre in the world to practically investigate the commercial potential of dynamic spectrum-allocation,

Re:antennas?

[SuperQ]

Antennas only affect the shape of the RF output, and the frequency range at which you can efficiently radiate.

Take some examples:
Omni-directional wifi antennas on most APs: a single stick with a fraction of the wavelength of 2.4ghz. Very simple, can do anything from SSB, AM, FM, or OFDM modulation.

Most of what software defined radios is talking about modulation changes, not frequncy changes.

The only difference between 802.11b and 802.11g is the modulation (CCK vs OFDM)

Re:Software radios a step towards real deregulatio

[SagSaw]

Sure, some people will say "What prevents Megacorp YYY from blasting 100,000 watts over every frequency?" That's pretty simple -- energy costs make it prohibitive to transmit anything but profitable data.

No, it's not practical to blast 100,000 watts over ever frequency. I'm not worried about such a shot-gun approach. What I'm much more worried about is the "sniper" approach. Let's say that you're using the newly-deregulated spectrum to provide some service. Perhaps your trying to operate a local public interest radio station, or providing internet service, or selling wireless telephone service of some sort. Now somebody with an interest in preventing _you_ specifically from providing your service comes along. Maybe they don't like the message from your radio station, or are your competitor in the ISP/phone market. All they have to do to keep you off the air is tranmit a signal which degrates the SNR of your signal sufficiently to render it useless. If they're willing to pay a little more for the power to produce their signal then you are for the power to produce your signal, they'll win.

I'd much prefer minimal regulation (i.e. just enough to force licensees to co-operate to avoid and resolve cases of interfearance.) to no regulation.