IIT Mandi develops tech to help future wireless communication applications overcome spectrum shortages

Researchers at the Indian Institute of Technology in Mandi have developed state-of-art solutions to enhance the reusability of radiofrequency spectrum which can overcome shortage and meet the growing demands of data communication in the future wireless communication applications. The findings of the team’s work have recently been published in IEEE Transactions on Consumer Electronics, and other IEEE journals.

According to the team, radio frequency waves or “spectrum” as they are known in the telecommunication field, are low energy radiation that is used in wireless communication.

The wireless radio frequency spectrum is a limited resource and is allocated by governments to telecom companies through a licensing process, they said.

The rapid growth in wireless communication technology in recent years and the projected exponential increase due to mass adoption of technology such as fifth-generation new-radio (5G-NR) and the Internet of Things (IoT) are expected to result in a massive demand for spectrum bands, they explained.

“Given the fixed-spectrum allocation policy by many governments around the world, including ours, it becomes important to use the available spectrum intelligently. Cognitive Radio Technology is considered one of the best ways to optimize spectrum use,” said Rahul Shrestha, Assistant Professor, IIT Mandi.

“The idea of Cognitive Radio Technology is that a wireless device such as a cell phone, used by the secondary user (SU) can be fitted with a special sensor that can detect such “spectrum holes” and use them when the main channel is unavailable or crowded.

“This forms the basis of a dynamic-spectrum access policy that can overcome shortages of available spectrum at a given time. The spectrum-hole detecting sensor that is built into the SU’s device is called a Stand-Alone Spectrum Sensor (SSSR),” he said.

Shreshta explained that the SSSR’s detection capability is often less than satisfactory due to problems such as hidden-node and signal-to-noise ratio (SNR)-wall problems.

“This leads to the unreliability of performance when the SSSR is used in real-time. Our research seeks to circumvent the problem. The work is on a technology in which the wireless device at the SU end is not equipped with a SSSR, but rather transmits the received parts from the spectrum band to a Data-Fusion center (DFC).

“The DFC then digitizes these parts and processes them using a single cooperative-spectrum sensor (CSR) instead of using device-level SSSR. The reliable decision is broadcast to all the SU devices for opportunistic communication.” he said.

This digital CSR ASIC-chip developed by IIT Mandi delivers excellent detection reliability of the PU under real-world channel scenarios with the best hardware efficiency and fast sensing time. The CSR chip can be used with any handheld mobile wireless communication device for accessing the unused spectrum.

“Specifically, it can be used in future 5G and 6G wireless communication technologies for enhancing spectral efficiency. In addition, this will enable massive deployment of IoT-based networks where numerous connected devices can use spectrum holes for break-less communication.

“The specific uses of cooperative spectrum-sensing technology in India cannot be understated and will help in establishing broadband services in remote and rural parts of the country,” said Rohit B Chaurasiya, research scholar, IIT Mandi.

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