IIT Mandi researchers seek to solve the problem of potential shortage in wireless spectrums

As WiFi is becoming a necessity in the present age, there is a rapid increase in the demand for wireless communication technology, such as fifth-generation new-radio (5G-NR) and the Internet of Things (IoT). What this means is that there will be a subsequent exponential rise in the demand for spectrum bands.

But the wireless radio-frequency spectrum is a limited resource. It is allocated by the governments to telecom companies through a licensing process. How to meet the rising demands then? Researchers from the Indian Institute of Technology (IIT) Mandi have come to the rescue.

The researchers have developed solutions to enhance the reusability of the radio-frequency spectrum which can overcome shortages and meet the growing demands of data communication in the future wireless communication applications, as reported by PTI.

In addition, it will enable massive deployment of IoT-based networks where numerous connected devices can use spectrum holes for break-less communication. Explaining, the research team said that radio-frequency waves, which are also known as "spectrums" in the telecommunication field, are low-energy radiation that is used in wireless communication.

"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. 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)," explained Rahul Shrestha, Assistant Professor at IIT Mandi, as mentioned in the PTI report.

"The SSSR's detection capability is often not 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 digitises 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," the professor added. 

"This digital CSR ASIC-chip developed by IIT Mandi delivers excellent detection reliability of the PU (primary user) 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," he added.

"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, a research scholar from IIT Mandi, as reported by PTI.