Reducing Interference

Why smart grids should adopt licensed spectrum

Technology has transformed our way of life, and power grids are no exception. Smart grids combine information technology with power distribution to not only benefit our homes but also our community and the nation at large. Owing to the continuous evolution of smart grids, the energy industry is experiencing a new era of efficiency and sustainability, contributing to the world’s environmental health while adding economic value.

Countries around the globe are realising the effectiveness of smart grids. The European Union directive to its member states is aimed at replacing at least 80 per cent of electricity meters with smart meters by 2020. According to a new report, Australia and New Zealand are predicted to invest $6.1 billion in smart grid infrastructure between 2017 and 2027. In 2015, India set up the National Smart Grid Mission (NSGM) that will plan, monitor and implement grid modernisation in the next decade to curb electricity theft. The total cost for all the projects and NSGM activities for the Twelfth Plan period is estimated at Rs 9.8 billion, including a budgetary support of Rs 3.38 billion.

Unlicensed spread spectrum, which is essentially shared spectrum and can be used by anyone, was touted as the technology that would free utilities from wires and meter readers. However, increasingly, utilities are debating whether smart grids should run on licensed spectrum in which the airwaves are owned and regulated. The efficiency and reliability of a smart grid network can only be guaranteed with a communications platform operating in licensed radio spectrum. The use of spectrum that is dedicated to the utility facilitates two-way communication between the utility and its customers and, when combined with the sensors in the electric distribution network, results in a secure and high-performing communications platform. There are many advantages of using dedicated spectrum and the top five reasons are as follows:

  • Tailored service at a fixed cost: Unlike other smart grids that work on low-powered mesh and other shared radio frequencies (RFs), the use of a dedicated and licensed radio spectrum means absolutely no interference with data transmission. This allows 100 per cent control and prioritisation of data transmission according to business requirements, thus ensuring a tailored offering at a cost under opex. In a smart grid deployment, every single aspect is accounted for with no hidden costs and no traffic volume-based charging. Since there will not be any need for additional bandwidth during data transmission, there will be a lid on costs.
  • Guaranteed frequency allocation for a longer period: The regulator typically allocates licensed spectrum on a long-term basis for more than 10 years. The number of years is decided according to the expected lifespan of a smart meter, thus ensuring that the entire smart network solution is considered as a whole throughout the process, which is not the case in unlicensed spectrum.
  • Low noise, strong signal and no interference: A major advantage of licensed spectrum is that the bandwidth is allocated exclusively for smart grid. This not only stops interference but also has a low noise floor. With no other applications or devices sharing the bandwidth, utilities can maintain excellent signal-to-noise ratios.
  • A dedicated channel for transmission of critical data: Utilities managing a large amount of data should have a dedicated spectrum channel for the transmission of critical data without any interference from other non-critical devices. Those using unlicensed bandwidth cannot guarantee tailoring the transmission of critical data due to the noise levels in the bandwidth.

Unlicensed spectrum operators tend to suggest that frequency hopping manages to sidestep interference in order to reduce interference. However, to carry out frequency hopping, bigger bandwidth is needed and countries like India often have a set size for unlicensed frequency, which tends to be insufficient for the number of endpoints needed and the amount of data carried.

  • High in-building and basement penetration: In densely populated cities, high in-building and basement penetration is very important when considering the roll-out of successful RF systems. The penetration for licensed bandwidth is very strong due to the higher transmission of power as compared to unlicensed bandwidth where the transmission of power is restricted.

In sum, although unlicensed spectrum is widely available at no cost, its signal-to-noise ratio is variable at best and it has high potential for interference. Utilities would need to use more repeaters, but that would not guarantee range, besides it is highly unreliable given high-interference and network complexity. On the other hand, licensed spectrum allows it to reliably transmit and receive customer usage data. It has an excellent signal-to-noise ratio due to exclusive use of the band, and has extensive range. As internet of things gains traction, the number of smart devices on the network will increase. Smart grids must operate on licensed spectrum to avoid any interference, risks or operational inefficiencies.

Amit Vaidya is Director, Strategic Customer Team, Sensus India.

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