How can SATCOM users leverage both LEO and GEO satellites for optimal coverage and reliability?

With lifespans ranging from 5-10 years, LEO satellites are replaced more frequently than GEO satellites (lasting 15-25 years). This allows for quicker technology refresh and advancements compared to the slower upgrade cycles of GEO satellites. LinkStar is an example where the 2nd generation satellites will have direct to mobile capability. In general, the manufacturing cost and speed of LEO satellites is also much lower and faster compared to GEO satellites.

I agree, the key benefits of LEO satellites are low latency, and high data transfer rates.LEO satellites can achieve a through put of 400 Mbps down and 200 Mbps up which is fibre-like connection. The latency expected from LEO satellites varies depending on the orbit but can be approximated to 30 ms. Time to install and set up the internet connection is also very quick.

The main challenge for LEO satellites is the CAPEX cost. They also have a very short lifespan of 5 years within which the next-generation satellites must be built and launched to replace them. The TCO is very high for an LEO satellite constellation. The other parameter is availability, the more satellites in the constellation the better the availability.

A Geosynchronous Equatorial Orbit (GEO) also called Geostationary orbit, is a circular orbit 35,863 km (22,236 mi) in altitude above Earth's equator. Objects in Geostationary orbit revolve around the earth at the same speed as the earth rotates. This means GEO satellites remain in the same position relative to the surface of earth. Advantages: -A GEO satellite’s distance from earth gives it a large coverage area. 3 GEO satellites can cover the whole earth except the polar regions. -Much cheaper to operate compared to LEO constellations. -Requires very rare hand-over compared to LEO constellations. Disadvantages -A GEO satellite’s distance also causes it to have a comparatively long propagation delay.

I believe that GEO satellites are tried and tested solutions with very low OPEX compared to LEO & MEO constellations. If you want to connect the other 3 billion, I believe GEO satellites are best positioned to deliver this ambition. Low maintenance and comparatively low-end user cost are the benefits of GEO satellites.

The low satellite diversity means that usually a user terminal can only communicate with one GEO satellite, sometimes two. This means that when a user terminal is in an area with terrestrial obstructions (such as trees or mountains), it may not be able to have a clear line of sight to the satellite and the service may be unavailable. LEO constellations have a high number of constantly moving satellites, therefore satellite diversity, the use of several satellites to serve the same user terminal, is an effective way to reduce the link outage probability for SATCOM users.

GEO is very good at specific solutions. One of the challenges and will always be a challenge is latency. Because of the orbit, the latency is roughly 450ms, if you add the fibre and teleport connectivity we are looking at 800 to 1000ms of latency. For a broadband application, this is not a problem. But if you are into banking and gaming applications which require very low-frequency GEO satcom is not best suited.

In my experience, leveraging LEO and GEO efficiently requires a blend of regulatory foresight and advanced technological integration. Navigating international regulations is key for seamless global operations. A focus on scalable infrastructure, capable of adapting to evolving space tech, is also vital. Incorporating software-defined networking allows dynamic resource allocation, optimizing LEO's low-latency for urgent applications and GEO's broad coverage for stable services. Machine learning for predictive analysis ensures proactive network management, facilitating seamless transitions between orbits. This approach would not only maximize coverage and reliability but also position an org as innovator in satellite communication.

The great 'idea' of blending GEO and LEO satellites and creating multi layer constellation is standing behind great bureaucratic walls. Not only strong frequency coordination is required to prevent possible technical interference problems but also coordination between 'new' space and 'old' space people. That requires great leadership , vision and cooperation among employees.

Both technologies can work hand in hand and a hybrid network is the way forward for Enterprise and Government satcom solutions. Hybrid networks also provide redundancy/back up thereby providing 100% availability.

As an employee at Eutelsat (the world's first GEO-LEO service operator) and after discussing with different key players in the market during Space Tech Expo, a hybrid fully integrated solution of LEO and GEO could be done on a Hardware level (Modems, Antennas, etc..) and/or on Software level (Processors onboard spacecraft or on Ground segment). Depending on the market needs, we can identify the real need of our customers (enhancing coverage, reducing latency, and/or expanding bandwidth capacity) and deliver the most reliable solution that meet our client’s expectations. I believe in this market and this insider's perspective underscores the real-world impact of our commitment to innovation !

In order to use a hybrid satellite network effectively one needs to understand the advantages of each orbit. Geostationary Earth Orbit (GEO): Requires only 3 satellites to have near global coverage. Does not cover the polar region. Has a longer propagation delay. Not ideal for a lot of high bandwidth terminals. Does not require many ground terminals. Requires terminals with higher power which can be more expensive. Can be more cost effective due to lower operational cost. Low Earth Orbit (LEO): Lower latency. Terminals require less power and direct to mobile possible. Requires Inter-satellite-links or many ground terminals. Very high operational cost. Based on the user requirements the best orbit can be selected in a hybrid network.

It is exciting to see the advancements within satcom, including the ability to integrate connectivity management platforms that use AI and ML to factor in LEO, MEO, GEO, 4G, 5G performance variations - plus consider the complexity of environmental factors. Machines can calculate and take the best decisions for connectivity, much more efficiently than a human can. Once you have a connectivity management platform in place, you set it and forget it. Let the decision engine consider all elements that impact performance and determine the optimal traffic route for specific traffic types. It works!

On selecting Satcom Services, one has to be very careful in selecting the right satcom solution. Satcom provides a variety of solutions starting from cost-effective broadband connectivity to mission-critical military services. Selecting the best-fit solution based on Cost, Quality & Availability will go a long way in serving the customer's needs. Having said this, we need to wait and see how LEO/GEO satellites are dynamic and how they serve customer needs in a hybrid way.