SpaceX Confirms Below 40ms Starlink Latency – But Is Download Speed Consistent?

Sep 24, 2020 13:47 EDT
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Space Exploration Technologies Corp. (SpaceX) has confirmed important details for its Starlink satellite-based internet service in meetings with the Federal Communications Commission (FCC). SpaceX's President and Chief Operating Officer Ms. Gwynne Shotwell spoke with FCC Commissioner Jessica Rosenworcel on Tuesday to convince the Commission to not grant Multichannel Video and Data Distribution Service (MVDDS) providers' petition for enhanced use of the 12GHz radio frequency spectrum for fifth-generation (5G) networks. In the meeting, the executive confirmed that SpaceX has consistently achieved latency below 40ms for Starlink, which is an important factor for the FCC's evaluation of the network in multiple arenas.

Her meeting built upon one between SpaceX's Director Space Policy Mr. David Goldman, Senior Vice President Tim Hughes and representatives from Commissioner Ajit Pai's office that took place last week. This encounter involved discussions around the 12GHz band and SpaceX's Starlink modification to change the constellation's altitude and other operational parameters.

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At the start of last month, representatives from SpaceX made an important presentation to the FCC (news broken by Wccftech) in which they revealed important details for Starlink. These included a $70 million investment in terminal production, information about the rate of satellite production and two speed tests that showed latency below 19ms. These tests were quoted by publications far and wide to demonstrate how Starlink had managed to reduce latency below 20ms, an achievement that put it at par with several broadband internet service providers.

Yet, even as the tests showed that Starlink is capable of achieving <20ms latency, this is purely in the extreme range and actual results should be expected to wary. However, judging by Ms. Shotwell's discussions, future users of the constellation should expect that latency will consistently fall below 40ms. Yet, whether this consistency will also apply to download speeds exceeding 100 Mb/s is uncertain.

Slide number four of Goldman and Hughes' presentation made to the FCC last week states that SpaceX has achieved download speeds exceeding 100 Mb/s through standard user equipment. However, whether this has been consistent is uncertain. Image: SpaceX NOTICE OF EXPARTE filed on Sep 19, 2020, in FCC's Docket WT RM-11768.

This uncertainty regarding the consistency of the download speeds stems from the difference in language between the Exparte notice for Ms. Shotwell's meeting and in the presentation slide referenced above. While in her meeting's notice, Mr. Goldman (who authored the notice) states that "SpaceX began by providing an overview of its progress to date in deploying its Starlink constellation, including beta testing that confirms latency consistently [EMPHASIS ADDED] below 40ms", the language of the presentation is more generic and simply states that Starlink was "Tested at over 100 Mbps".

Therefore, it's only logical to assume that while the company has reduced latency below the aforementioned threshold, download speeds are far from being certain. Starlink data transfer rates were also mentioned by Kate Tice, Senior Systems Certification Engineer at SpaceX, during the live feed of the company's 11th launch of functional Starlink satellites. Back then, Ms. Tice explained that SpaceX had transferred "hundreds of gigabytes of data" through laser links between two satellites. Naturally, since this was a test, it's safe to assume that the company is far from achieving this for all of its currently deployed satellites.

Additionally, it's also uncertain if SpaceX will be able to consistently achieve low latencies for Starlink if the FCC does not grant the company's constellation modification application. The grant of this application and the MVVDS Petition are interlinked as the latter has also claimed that approval will further restrict their ability to provide terrestrial services.

SpaceX has rejected these arguments by stating that earlier claims by the MVDDS providers made earlier demonstrated that satellite internet and their services could co-exist in the 12GHz band and therefore fresh claims that the two systems are incompatible are incorrect. The company is also busy testing Starlink all over the United States and in the polar region of Alaska - which forms an integral part of its dealings with the FCC and the request for modification.

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