Cambridge Consultants' Pizzicato all-digital radio transmitter.

Fully digital radio transmitter could be turnkey solution for IoT

Cambridge Consultants has successfully completed initial trials of the world’s first fully digital radio transmitter. This potentially represents a turning point in wireless design and could prove invaluable in realising the potential of the Internet of Things (IoT) and 5G technology.

The new breakthrough – codenamed Pizzicato – unlocks the potential of the IoT, opening the door to a new dynamic way in which the predicted 100 billion IoT devices can operate together in a crowded radio spectrum. It will also enable the creation of 5G systems, with multiple radios and antennas.

The Pizzicato digital radio transmitter consists of an integrated circuit, outputting a single stream of bits, and an antenna. No conventional radio parts or digital-to-analogue converters are involved. Patented algorithms perform the necessary ultra-fast computations in real time, making it possible for standard digital technology to generate high-frequency radio signals directly.

Unlike ‘software-defined radio’ (SDR), there is no mix of analogue and digital components – the radio is completely digital, which could enable new ways of using the spectrum intelligently.

“Our first trial of the technology has created 14 simultaneous cellular base station signals,” said Monty Barlow, director of wireless technology at Cambridge Consultants. “It is the potential which is so exciting. If we’re going to get high-speed broadband to every mobile phone in the world, we’ll need lots of tiny, high-performance radios in those phones.

“The radios will be squashed together in a way that analogue just doesn’t tolerate. Like mainstream microprocessing, a Pizzicato-based radio would directly benefit from Moore’s Law – shrinking in cost, size and power consumption with each new generation of silicon fabrication.

“It could also be programmed to generate almost any combination of signals at any carrier frequencies, nimbly adapting its behaviour in a way that is impossible in conventional radios. It is early days for this technology but we believe radio design has reached a turning point.”

Good radio spectrum is a scarce resource – only low frequencies (1GHz or lower) propagate well over distance or through walls, so they are in great demand. Greater efficiency requires the use of dynamic or ‘cognitive wireless’ techniques to sense the radio environment and switch parameters on the fly. This could give access to more of the estimated 90 per cent of the allocated spectrum which is not in use at any one time.

Making use of the higher carrier frequencies of 10GHz and beyond, however, will require techniques such as meshing and beamforming to circumvent the inherently poor range – and the analogue parts of radios are becoming an increasing bottleneck.

“Crowding 50 analogue radios together on one chip, switching their operational parameters every few microseconds and expecting them to work at 60GHz is an analogue designer’s nightmare,” said Barlow. “With Pizzicato, we have created a glimpse of future disruptive technology – a radio built purely from computing power.”

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