Researchers at Cornell University have developed a new radio-on-a-chip that could lead to cheaper and more flexible wireless systems. For example, this innovative technology could be utilized by smartphone makers so they can develop a single model for each cellphone to work anywhere in the world. Popularity for single-chip radios have soared among communications hardware over the years because most of the characteristics of these devices are determined through software instead of intrusive hardware components. Consequently, these radio-on-a-chip accessories are called software-defined radios.
Filters are required to protect the highly sensitive circuity of receivers from transmitted signals in many transceiver devices, which can be up to a billion times more powerful than the signals these radios receive. If not for these filters, single chip radios would be bombarded with signals, and incapable of functioning properly as a result. Single chip radios simultaneously transmit and receive signals on different frequencies in cellphones so as a result, users can listen and speak at the same time without sequentially leaving the outgoing or incoming signal frequencies open – i.e. you don’t have to say “over” every time you finish speaking.
According to the Cornell researchers, they also discovered how to generate and transmit a signal that’s allowed to be canceled out on the reception side, which further mitigates the need for hardware filters. This new design could help drop the price of software radios.
“The reason why it works is a unique design…” says Alyssa Apsel, a professor at Cornell who is part of the team that developed this radio chip. “The radio generates several signals that in one direction combine to produce the desired transmit signal. In the other direction they cancel each other out, thus doing the job of a filter.”
Years ago, cellphones that covered three frequency bands would have worked anywhere in the world. With the new LTE technology however, these frequencies are now available in over 30 different bands. As countries begin to specify band assignments to their specific needs, this could wind up complicating matters moving forward, but also make a device like a reprogrammed radio for instance, more useful in these particularly affected regions.
“We can enable this function at any frequency, just by tuning some parameters…” Apsel noted. “So we can make a radio that is truly reconfigurable, changed on the fly to spectrum in your location.”
Researchers at Cornell developed and covered frequencies ranging from 300 MHz to 5 GHz. This range covers several active communication bands for cellphones, WiFi, amateur radio, emergency services, along with fixed wireless broadband and satellite communications. Researchers managed to gain 25 dB of isolation between transmission and reception signals. While hardware filters will normally isolate anywhere between 20 dB to 40 dB, researchers at Cornell are confident they can reach at least 50 dB in isolation moving forward.