LEOs, MEOs and lasers: the future of broadband satellite

broadband satellite
Jonathan Brewer from Telco2 talks about the broadband satellites at APNIC44.

Over the next five years, 10,000 new internet satellites from seven different consortia will be launched into orbit to deliver broadband services quite unlike what we have come to expect from satellite broadband up until now. In fact, explained Telco2 consulting engineer Jonathan Brewer on the first day of APNIC44 in Taichung, Taiwan, the amount of bandwidth coming down from the sky is set to explode by three orders of magnitude.

The further away from city centers and the lower the population density, the more costly it is to use anything but satellite. Latency is the problem, Brewer said. “People buy cars for the horsepower but they feel torque when they accelerate. Likewise, humans buy bandwidth but surf latency.”

Once a web page takes longer than 320ms to load, or once a voice call has a delay of more than 320ms, everyone will know it is slow. This has been the challenge for geosynchronous earth orbit (GEO) satellites in delivering broadband internet – orbiting at 36,000 km means a round trip of 480ms for radio waves to travel up and down. To clarify, that latency is for the radio signal itself, which defines the latency of everything running over it.

That’s why companies are looking at medium earth orbit (MEO) and low earth orbit (LEO) satelites, which are closer to Earth, which in turn improves latency considerably.

One technology that could change the broadband satellite game is free-space optics – laser communications without the fiber.

Brewer explained that radio actually travels 33% faster than light in a fiber optic cable, as the light needs to bounce around and take a much longer path than the direct path in free space. “However, the flip side is that free space is also occupied by rain, snow, clouds and Elon Musk with his space suits and rocket ships.”

It’s early days for laser comms by satellite, but one of the most interesting new systems will be Laser Light, the world’s first all-optical MEO constellation. Laser will be the fastest way to get from LA to Sydney, Brewer said. To avoid clouds, each ground station can have up to 12 satellites in view. Each beam is 100 Mbps – with 7,200 lasers pointed at the earth at any given time, that is 7.2 Tbps of bandwidth.

The hottest space race is for LEO, which of course has the lowest latency. Iridium, Globalstar and Orbcomm already have LEOsat constellations. OneWeb – a consortium comprised of Airbus, Boeing, Coca-Cola, Qualcomm, Virgin, Softbank and more – is looking at launching a network of 720 satellites each with 6 Gbps of bandwidth for a 7.2 Tbps network. O3b and Iridium are going to launch a 76-satellite LEOsat network with optical laser cross-connect for switching in space.

However, the most ambitious LEO project is SpaceX and Google’s plan for a constellation of 4,425 satellites in 2019. This 88.5 Tbps network will also use space laser cross-connect and promises to offer a 1 Gbps service at any point on earth.

LEOs and MEOs aren’t necessarily taking GEOsats out of the equation – GEOs are undergoing serious upgrades in design. Take for example, nbn co’s Sky Muster, a next-gen GEOsat that is the size of a bus and weighs 6 tons. (For comparison, the Optus D2 GEOsat weighs just 1,100kg.) Sky Muster uses the higher frequency Ka-band ,which has much more spectrum than C band and provides much more antenna gain. Also, its smaller geographical footprint means the same frequency can be reused much more densely than lower C-Band frequencies. That increased density means each of the two Sky Muster satellites provide a combined 135 Gbps of bandwidth. The tradeoff is that Ka-band is very prone to rain fade.

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