From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id AEDD63CB37 for ; Sat, 2 Mar 2024 10:45:23 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.de; s=s31663417; t=1709394321; x=1709999121; i=moeller0@gmx.de; bh=7KRGBTCINNA1KfALUVgHbQ6NGOq1DS0SYoOttUDWQnE=; h=X-UI-Sender-Class:Subject:From:In-Reply-To:Date:Cc:References: To; b=sWeClDuXKQi703ROgQiBy/qJZi15XBe7GO8UA5zMvUFiuaL7Ti0i4dLLaE6leFK9 2wj27pS62J81YTbLfbKsnoB9DdAA+am2mupQJvN6+/q/doKTECCOYaPjxcdKvRT4p qk33qUbCN2hd8I3QI0AdennwF2tc1YhujY079sOQrZYVben53fkvGUtoI9V7pu52I Sh/FjtZUMX5a+/PcK+2z5f2bDJF3ynBAW//KfsXuslzw7TQGBRBYWWKsedc2H6vy4 dtIQTDpiZ/i9i61RewHzoTyykbiV5O/uCK8zNMHlylouYL7Va9m+U5PMMxVBnsEOG bmMQvt5y+6G5ssa5ag== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from smtpclient.apple ([77.3.124.127]) by mail.gmx.net (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MLQxX-1rNx5u2q6F-00IWtQ; Sat, 02 Mar 2024 16:45:21 +0100 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.400.31\)) From: Sebastian Moeller In-Reply-To: Date: Sat, 2 Mar 2024 16:45:11 +0100 Cc: Dave Taht via Starlink Content-Transfer-Encoding: quoted-printable Message-Id: <5A2F0F5F-2E77-4764-9859-D447764077D8@gmx.de> References: To: Hesham ElBakoury X-Mailer: Apple Mail (2.3774.400.31) X-Provags-ID: V03:K1:rdNw5SxRUolgosnJJBHee8oaklB/XqPnOUcrFDqxuZcBv0MaMfj IqRGAiKKKl7yDctKCXkgC/dQ/tvxu3xNKivML6KaXsdIg3N8ZikV4RJJBuei4nPgsH7KFdr NVZqpRkEC1jQmgJTVzeM+dMzqfZT8CEEkH41/f17FqdIVByInkxfkfRORVs7zXSkUbJKXXv ZTBjJdMkWm9xm8zdFKS9Q== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:UhkSVtBupwA=;l4zYavps0wLWBEwqlvJ4jAt8/I0 EgQO6EFmd1vj8M0lzktO16853nEfS3GIfttnS8/kWT3cVO4mCgbE4KjFlgNIFU682KxozZCp7 hWU8WKSCKjg9tt/rXiO22Mp0ShbqFXgi9jxSFXoXPwaj9HUAsaP92sah7CMPReIdPYtNMjf+a JYW4Gcvf50ljfFCQCTV1qfjVl+XgrecYVnG2jcemGdN4hH2QFucp3yaFBI8m2+ctayhV6Krqg no574H9UDYYWVUyZ8dqYuziGJwOfFsil6llbvET2d5HqLEUaybom0wOX7JD9twPbOuQH9uUum y+qdnABAoos5RSDtFdmQHfgRT/ZzS9aFk0CLWcLa2HvajD/gCqbkKDvyqtis2kwmPzwOfx82Q iNasiYMs8eVxB4/JdklPzZESNCOg3UJkHaUErRABUj9M2ajnVxLv9Y4H8gZsXcdmrDNnW+Ugi 19wQftLsim1X11k8Bs3YPGh4pCJ3AeqMmu4iBQPd0oFcWx3S/8Sgj0t+ji9Ivpa5AuZnhufh+ AOkvW+QZB6QGiBawSEwjmndwhibV1EZGIfifR/zZyOMzAF8BH3Tlyce4mvgmda7ug7zcvwB8j f4L4SkTdqQrCFRgPlXHPOlhynsH9ZpTPoXggr20hdBF3W53YWUdJN5+F0YnhKSSi7qzHpKtKs WNZif8/1UQwtrniMN1kUOkICcWN+RKbuyX3y0Nofmteb0XvNYyzXlhPzE7ie5LzqPgetezli0 l1RoxGYthrlKxCsrlFVfOH26SCJddmhW+PHbMmWkOffjnYsaTRzF6DC/91gJxQUp7EURdxuvv 76GODN9ZYMh4DU9HsWPiegZFtLvS8eWtJZ3V3ohN6pveI= Subject: Re: [Starlink] Time Synchronization in Satellite Networks X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 02 Mar 2024 15:45:24 -0000 Hi Hesham, caveat, this is far from my area of expertise, but I would simply try to = get GPS/Glonass/Galileo antennas into the birds and have each sync their = clock individually from such a source, which would remove the necessity = for time synchronisation protocols. That said, I see neither PTP not NTP = as suited, as both presumably assume that server and clients do not move = to fast in relation to each other, while arbitrary members of a LEO = constellation might have quite large relative speds, no? Regards Sebastian > On 2. Mar 2024, at 16:25, Hesham ElBakoury = wrote: >=20 > Hi Sebastian, > Can we still use PTP and NTP for time synchronization in Satellite = networks or we need new protocols? If we need new protocols, do such = protocols exist? >=20 > Thanks > Hesham >=20 > On Sat, Mar 2, 2024, 7:18 AM Sebastian Moeller = wrote: > Hi Hesham >=20 > > On 2. Mar 2024, at 16:03, Hesham ElBakoury via Starlink = wrote: > >=20 > > Time synchronization, for satellite networks, faces several = challenges: > > 1. Signal Propagation Delays: Unlike terrestrial networks where = signals travel through cables at the speed of light, >=20 > [SM] The speed of light in your typical glas fibers (and accidentally = the information propagation speed in metallic conductors) comes in = roughly at 2/3 of the speed of light in vacuum, while the speed of light = in air at see level is a mere 90 KM/s slower than in vacuum.=20 >=20 > > satellite communication involves signals traveling vast distances = through space. This creates significant delays. >=20 > [SM] Sure distances might be larger, but propagation speed is around = 100000Km/s faster... my main point is speed of light is a) dependent on = the medium b) not the things that differentiates space from the earth's = surface here, but mere geometry and larger distances on larger = spheres... >=20 > > 2. Clock Drift: Even highly precise atomic clocks, used in = satellites, are susceptible to "drift" - gradually losing or gaining = time. This drift, caused by factors like temperature variations, = radiation exposure, and power fluctuations, can lead to inconsistencies = in timekeeping across the network. > > 3. Signal Degradation: As signals travel through space, they can = degrade due to factors like atmospheric interference, ionospheric = disturbances, and solar activity. This degradation can introduce noise = and errors, impacting the accuracy of time synchronization messages.=20 > > 4. Limited Resources: Satellites have limited power and processing = capabilities. Implementing complex synchronization protocols can be = resource-intensive, requiring careful optimization to minimize their = impact on other functionalities. > > 5. Evolving Technologies: As satellite technologies and applications = continue to evolve, new challenges related to synchronization might = emerge. For example, the integration of constellations with thousands of = satellites poses unique synchronization challenges due to the sheer = scale and complexity of the network. > > These challenges necessitate the development of robust and efficient = time synchronization protocols for satellite networks and an integrated = satellite and terrestrial networks > > Are you aware of such time synchronization protocols? > > I would think that using Satellite simulators is the most viable way = to develop and test these protocols given that using satellites is not = that easy. > > Thanks > > Hesham > >=20 > >=20 > >=20 > > _______________________________________________ > > Starlink mailing list > > Starlink@lists.bufferbloat.net > > https://lists.bufferbloat.net/listinfo/starlink >=20