COMMStellation™ - A Low Latency Satellite Constellation for Broadband Communications

摘要

The global market demand for mobile broadband bandwidth is growing at an unprecedented pace. The challenge, as consumers rely more and more on these devices, is the management and expansion of the global infrastructure required to handle advances in technology and the resulting data-usage explosion. There are numerous issues that must be overcome, including cost, speed, capacity, and universal access. In 2011, 71% of the world's population (~5B people) had no access to high speed Internet. It is here that Low Earth Orbit (LEO) satellite constellations can play a critical role in handling increased wireless-broadband traffic for wireless providers, offering low latency and worldwide coverage. Low latency is especially important to the quality of service of current and emerging Web 2.0 type of applications (social networking, etc). As satellites age and require replacement, propulsion systems on each satellite allow for controlled re-entry for disposal, while additional assets from on-orbit and ground spares will replace them. Microsat Systems Canada Inc. (MSCI) has studied the issue and developed the COMMStellation™ initiative in response. A satellite constellation composed of 72 operational satellites in 6 near-polar orbital planes at 1000 km, provides full Earth coverage, with up to 8.8 Gbps of data throughput supported by each satellite. Two additional satellites will be placed into each orbital plane for redundancy. The COMMStellation™ mission is discussed and details are provided on the technical hurdles identified in the constellation, satellite, and teleport designs, and how MSCI plans to address them in the design of the system. Techniques such as Adaptive Coded Modulation (ACM) are used to allow for bandwidth-efficient broadband transmissions at Ka-Band while providing automatic adjustments in the face of temporary fades due to localized inclement weather. Ground station site diversity is also implemented in regions with significantly rainy climates to maintain the availability goal at non-trivial data rates. Power and link budgets are presented to show how COMMStellation™ can meet the challenges of providing high data throughput for the entire world.