What are the advantages and challenges of using LEO satellites for broadband services?

Low Earth Orbit (LEO) satellites are much closer to the earth than GEO satellites, ranging from 500 to 1,500 km above the surface. LEO satellites don’t stay in fixed position relative to the surface like GEO satellites, and are only visible for 15 to 20 minutes each pass. Advantages - A LEO satellite’s proximity to earth results in a lower propagation delay -Can cover polar regions Disadvantages -Many LEO satellites are needed for constant connectivity, which can be costly -A LEO satellite has a smaller area of coverage requiring a high number of ground stations without ISLs -Atmospheric drag effects LEO satellites, causing gradual orbital deterioration

Maybe HAPS can supply pointed coverage where terrestrial nets cannot instead of deploying a LEO net, or supplement a less dense LEO net

Advantages: Shorter propagation delay, Global Coverage, Low latency. Challenges: Limited coverage - LEO satellites can only cover relatively small areas due to their lower altitude. Cost - The cost of launching and maintaining LEO satellites is higher. Security and privacy concerns - LEO satellites could introduce new security and privacy concerns. Despite these challenges, LEO satellites are expected to play a significant role in the future of broadband services mainly in remote areas, hill stations, maritime, in-flight network connectivity, natural calamity disaster-affected areas and war zones.

LEO satellites may not necessarily provide more bandwidth than MEO and GEO satellites on a per satellite basis but low altitude allows high frequency reuse, so a large fleet of satellites do. Yet, this may also come at a price in the form of constrained addressability given that LEO satellites spend a large portion of their orbital period over oceans and inhabited regions

LEO satellites are much closer (around 500-1500km) to the user than GEO satellites (35,786 km). This means that the user terminal requires much lower power to close the link budget. This fact has resulted in companies exploring direct LEO to smartphone connectivity. For text messages and low bandwidth services such as IoT this is already possible. AST&Science and Starlink are working on larger bandwidth internet connectivity directly to existing smartphones. LEO satellite constellations provide higher elevation angle to the user terminal, which means better signal strength and less outages when in areas with terrestrial obstructions. Very Low Earth Orbits (VLEO) are below 450 km and there have been some recent filings for this orbit.

Advantages: Can be used anywhere in the footprint. Easy to set up. Very quick to deploy. Decent performance most of the time, including low latency. Disadvantages: Asymmetrical b/w. Subject to degradation in heavy snow and rain, leaves and trees cause obstructions, price per bit is greater than wireline services.

A significant challenge for LEO satellites in broadband is managing the dynamic spectrum. LEO's proximity to Earth complicates frequency coordination with terrestrial networks. Innovative spectrum sharing and interference avoidance strategies are needed, especially with expanding 5G networks. Collaborative regulatory frameworks are essential to accommodate rapid changes in space and terrestrial communications. Effectively managing the spectrum is crucial for the success of LEO satellite broadband.

LEO satellites also require more ground station when these satellites do not have inter-satellite-links (ISLs). The reason so many ground stations are needed is that the coverage area of the LEO satellites is relatively small and the data send from a used needs to be send to a ground terminal within that satellite coverage area. As the operational costs for a high numbe of ground stations can be high, ISLs can be used which enables communication between satellites and routing of traffic to one of few strategically placed ground terminals. ISLs make the satellite more complex and there is therefore a complexity and total cost trade-off.

They have artic coverage now. Do a simple Google search. Or some slight research on your article. I mean there is no comparison between the two. Faster lower latency and cheaper

The information here probably need some updating. But apart from Starlink, Eutelsat/OneWeb, and Kuiper, we could also add Telesat, E-space, and future constellations from the EU (IRIS2) and China (Guowang) as shaping the broadband landscape. These new entrants highlight a diversifying LEO ecosystem. This expansion brings regulatory challenges, particularly in spectrum and debris management. The crowded LEO space demands globally harmonized policies and a collaborative regulatory approach. This ensures safe, sustainable space use for all, balancing commercial interests with global space safety and accessibility. Such regulatory evolution is crucial for the thriving future of LEO broadband services.

Oneweb was acquired by Eutelsat and is now Eutelsat OneWeb a subsidiary of Eutelsat Group. Nearly all required satellites (648) for operational service for Eutelsat OneWeb have been launched. A disruptive LEO idea is to have a large antenna on a LEO satellite to provide communication direct to unmodified smartphones. A scaled down (from operational) test satellite called BlueWalker 3 (BW3) was launched and the 693-square-foot (64 m2) antenna array of BW3 was successfully unfolded to full deployment in November 2022. In April 2020, AST & Science had applied to the FCC for permission to operate a constellation of 243 communications satellites in 16 orbital planes at altitudes between 725 and 740 km (450 and 460 mi).

The following are key players in LEO satellites: # Starlink (SpaceX) - Planned: 42,000 satellites - Operational: 5,242 satellites as of May 2024 # Eutelsat OneWeb - Planned: 648 satellites - Operational: 630 satellites # Project Kuiper (Amazon) - Planned: 3,266 satellites # China GW - Planned: 12,992 satellites

One of the objectives of the LEO constellations providing broadband services is to connect the unconnected billions, who live in areas without terrestrial telecommunications infrastructure. The problem to reach these unconnected citizens the price of the satellite connectivity needs to be affordable for local standards. However, operating a LEO constellation is relatively expensive. In countries like the UK the solution is the government subsidizing satellite connectivity in rural areas as rolling our terrestrial infrastructure is cost prohibitive. Reaching billions of unconnected in Africa will require special pricing, maybe subsidized by social media companies that want to increase their user numbers,

LEO satellites often utilise higher frequency bands, such as the Ka-band, which allows for greater data throughput compared to traditional Ku-band used by GEO satellites. During a test project involving video streaming over satellite links, we observed that the Ka-band allowed for higher bandwidth, enabling multiple high-definition video streams to be transmitted without buffering. The use of higher frequency bands in LEO constellations ensures faster data rates, which is critical for supporting bandwidth-heavy applications like 4K streaming, cloud services, and large data transfers.

Providing connectivity to train in areas when the terrestrial infrastructure is not available is an interesting use case. As the train moves there is a possibility of line-of-sight obstruction to GEO satellites due to terrestrial obstacles. Of course, the same obstructions could be the case for a car. In a LEO constellation there are many satellites moving over the user terminal whereas there is usually only on geostationary satellite. Due to the high number of moving satellites for LEO there is a much higher chance of having a better signal to a LEO satellite and higher availability for this use case.