C-band Satellite Communications – Spectrum Crunch?


c-bandC-band Satellite Communications

The future commercial viability of C-band satellite communications will increasingly become less viable as the band comes under threat from the International Mobile Telecommunications (“IMT”) sector, according to spectrum specialists we have spoken to.

What is C-band?

C-band is a name given to the portion of the electromagnetic spectrum, including wavelengths of microwaves that are used for long-distance radio telecommunications. The IEEE C-band (4 to 8 GHz) – and its slight variations – contains frequency ranges that are used for many satellite communications transmissions. Commercial satellites operating in C-band primarily use the frequency band from 3400 to 4200 MHz for transmissions from the satellite to an Earth station (the “downlink”), and the frequency band from 5925 to 6725 MHz for transmitting from the Earth station to the satellite (the “uplink”).

Since the C-band frequencies represent a rather large continuous block of radio spectrum, they have for many years been coveted by the terrestrially-based wireless telecommunications industry. The International Mobile Telecommunications (“IMT”) community is forecasting a potentially huge increase in spectrum demand for their services over the coming years. Mobile operators are currently looking at using additional spectrum, including C-band frequencies, and view the C-band as a potential source of additional bandwidth to serve their current and future customers. In their lobbying efforts for additional spectrum, the well-funded IMT community has the advantage that everyone is familiar with the use of smart phones, while the role and wide-spread use of satellites, to name cellular backhaul as just one example, is far less known and obvious. The mobile wireless industry has begun to use its significant clout to push governments and international regulators to identify parts of the C-band spectrum now used for satellite communication for use by terrestrial wireless devices.

In 2015, the International Telecommunications Union (“ITU”) will hold the World Radiocommunications Conference (“WRC-15”). WRC-15 will consider a proposal by the wireless industry to identify a portion of the C-band for IMT usage. Consequently regulators all over the world are considering the reallocation. The reallocation of the C-band would likely involve sharing the band between the two services, and imposing geographic separation between them – for example, so that satellite services could only be used in rural or remote areas and mobile services could only be used in metropolitan areas. This proposal could have a significant impact on satellite users of the C-band. As C-band availability is reduced customers will make mass migrations to the more efficient and available Ku-band and Ka-band. So perhaps its all actually good news because the satellite operators can simply oblige their C-band customers to make an upgrade to better technology, especially at the Ka band which seems to be the hot new thing for data.


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