From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mo4-p00-ob.smtp.rzone.de (mo4-p00-ob.smtp.rzone.de [85.215.255.21]) (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 858AD3CB37 for ; Sat, 2 Mar 2024 10:38:54 -0500 (EST) ARC-Seal: i=1; a=rsa-sha256; t=1709393933; cv=none; d=strato.com; s=strato-dkim-0002; b=PRsmbaVWbGSpotG8M2e/ky03n5IqUPCDB5962Ti3qWoz2G6yna4wEh0+2NAGIXRJjP MwRKHahRCsnW1pbEkXl91Z+DFG6wp/9+l2zVByVLhyBR0KhFLh9x4L49ZIkCPlGNMhOh 55uw/RIziKqVEc6vV38k4mgH2lyoODmnnNWIBkzqlPolrAf/XcKOsNiIHEK/aj185Vdi gYm30YvwZ1sQutize6p2BuxRnAIYxq3qDYyBpNfeNpArsNT0MZI6QsL1gz12xBUe06T5 VgWygrvXaDQXYvIIftcZgSoJr6LtCiYXkfIhLT1bBOfoUKn0is1sdACZO6MR/I5zB9NI X3Lw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; t=1709393933; s=strato-dkim-0002; d=strato.com; h=Message-ID:References:In-Reply-To:Subject:CC:To:From:Date:Cc:Date: From:Subject:Sender; bh=KRnLAQVEJgP+jYUtyT+KfICxWfr1O7Lbylha2y1nnxQ=; b=I8VL7qelCASlXn8B1nVEM+UlSrMjUbtmfO7x8+OPnxEMljnYtq/sDeE6emUvy8hERJ +8oLkyTmWLiAwFsyjYRb52H2mN612xUAdiY62nZHEPWJRJx/gvGuEvwYg0spE1svuQun QV2vj7K7nwS+yfQiUl0oyOoMZ/hHsE712xZny7E/mmrCIpSndbso6OZ8o/KOzdQIq1ZB TYNrKJ/HUoDBvONTHxGzyzq7lAfyJybCw0kgy4BrcSuhUhu04pStGPKixqFqrSeukHkF zp4dBdvuWXnKpC/QzZEIo8/GmitJ6YFyoc7CeaMTLLzdCMwFDC3J1aKi8SXPxMkJpzYq U6wA== ARC-Authentication-Results: i=1; strato.com; arc=none; dkim=none X-RZG-CLASS-ID: mo00 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1709393933; s=strato-dkim-0002; d=vdr.net; h=Message-ID:References:In-Reply-To:Subject:CC:To:From:Date:Cc:Date: From:Subject:Sender; bh=KRnLAQVEJgP+jYUtyT+KfICxWfr1O7Lbylha2y1nnxQ=; b=EqrzLohMAaLYOYfdC5Eer29gBKOSTIOJWJ/FshRGHa0894Cl8EEXbT2pnRtSVLYx8O p5uQeWTKmfCnjgT2/oPiKf6JYIbWaFjQbxn4Y59Limyr+TrCLEW88onZjTnFoJ156h/4 4inhW3BnKeQlvK6p/gzbuorjVEymZkF5Nn8dz4A94vT1wGFKFEm0hC10ewJ/hD9T3hfj mMECgjd3Z/UlAbcvQf4H3jqIxj5KqlA191QEOIAwmvyKoaAzGT/OuxJygewxy+96QSbS mZ18AS3wN3SHC6XNZ/+0mi6BXcBNnizaZaP4gH/gDOQdZ1uhuEMoFV7so2lvfya7LyyH +FUA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; t=1709393933; s=strato-dkim-0003; d=vdr.net; h=Message-ID:References:In-Reply-To:Subject:CC:To:From:Date:Cc:Date: From:Subject:Sender; bh=KRnLAQVEJgP+jYUtyT+KfICxWfr1O7Lbylha2y1nnxQ=; b=OafrNUEKcIEknZYMOHd/vjtfSHLkvrM8l7D5mNFlBIp1AKIEgaszl10mWvJrL1ZiaB RR4FHjwt+r9sdIVt+cAg== X-RZG-AUTH: ":L3oAZ2C+f+0rWOBO0o0FCt0K/NLKyHz9AX0t9Z6ZpYP726Y0erZDHmmLmSs=" Received: from [127.0.0.1] by smtp.strato.de (RZmta 50.2.0 DYNA|AUTH) with ESMTPSA id Q628ee022FcqClx (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Sat, 2 Mar 2024 16:38:52 +0100 (CET) Date: Sat, 02 Mar 2024 17:38:50 +0200 From: Christian von der Ropp To: Hesham ElBakoury , Hesham ElBakoury via Starlink , Sebastian Moeller CC: Dave Taht via Starlink User-Agent: K-9 Mail for Android In-Reply-To: References: Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=----S1VVFEZ65SIGMCJQX8YGJHJ9QOQ0MD Content-Transfer-Encoding: 7bit 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 15:38:54 -0000 ------S1VVFEZ65SIGMCJQX8YGJHJ9QOQ0MD Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Why not acquire the time directly from by the satellite terminal and run lo= cal NTP servers instead of syncing via the Internet? LEO satellite terminal= s always have onboard GNSS antennas for geolocation which is necessary to f= ind the satellites, so integrating a local GNSS-disciplined Stratum-1 NTP s= erver seems trivial to me=2E Am 2=2E M=C3=A4rz 2024 17:25:59 OEZ schrieb Hesham ElBakoury via Starlink = : >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? > >Thanks >Hesham > >On Sat, Mar 2, 2024, 7:18 AM Sebastian Moeller wrote: > >> Hi Hesham >> >> > On 2=2E Mar 2024, at 16:03, Hesham ElBakoury via Starlink < >> starlink@lists=2Ebufferbloat=2Enet> wrote: >> > >> > Time synchronization, for satellite networks, faces several challenge= s: >> > 1=2E Signal Propagation Delays: Unlike terrestrial networks where sig= nals >> travel through cables at the speed of light, >> >> [SM] The speed of light in your typical glas fibers (and accidentally t= he >> 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=2E >> >> > satellite communication involves signals traveling vast distances >> through space=2E This creates significant delays=2E >> >> [SM] Sure distances might be larger, but propagation speed is around >> 100000Km/s faster=2E=2E=2E my main point is speed of light is a) depend= ent on the >> medium b) not the things that differentiates space from the earth's sur= face >> here, but mere geometry and larger distances on larger spheres=2E=2E=2E >> >> > 2=2E Clock Drift: Even highly precise atomic clocks, used in satellit= es, >> are susceptible to "drift" - gradually losing or gaining time=2E This d= rift, >> caused by factors like temperature variations, radiation exposure, and >> power fluctuations, can lead to inconsistencies in timekeeping across t= he >> network=2E >> > 3=2E Signal Degradation: As signals travel through space, they can de= grade >> due to factors like atmospheric interference, ionospheric disturbances,= and >> solar activity=2E This degradation can introduce noise and errors, impa= cting >> the accuracy of time synchronization messages=2E >> > 4=2E Limited Resources: Satellites have limited power and processing >> capabilities=2E Implementing complex synchronization protocols can be >> resource-intensive, requiring careful optimization to minimize their im= pact >> on other functionalities=2E >> > 5=2E Evolving Technologies: As satellite technologies and application= s >> continue to evolve, new challenges related to synchronization might eme= rge=2E >> For example, the integration of constellations with thousands of satell= ites >> poses unique synchronization challenges due to the sheer scale and >> complexity of the network=2E >> > 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 tha= t >> easy=2E >> > Thanks >> > Hesham >> > >> > >> > >> > _______________________________________________ >> > Starlink mailing list >> > Starlink@lists=2Ebufferbloat=2Enet >> > https://lists=2Ebufferbloat=2Enet/listinfo/starlink >> >> --=20 Diese Nachricht wurde von meinem Android-Mobiltelefon mit K-9 Mail gesende= t=2E ------S1VVFEZ65SIGMCJQX8YGJHJ9QOQ0MD Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Why not acquire the time directl= y from by the satellite terminal and run local NTP servers instead of synci= ng via the Internet? LEO satellite terminals always have onboard GNSS anten= nas for geolocation which is necessary to find the satellites, so integrati= ng a local GNSS-disciplined Stratum-1 NTP server seems trivial to me=2E

Am 2=2E M=C3=A4rz 20= 24 17:25:59 OEZ schrieb Hesham ElBakoury via Starlink <starlink@lists=2E= bufferbloat=2Enet>:
Hi Sebastian,
Can we still use PTP= and NTP for time synchronization in  Satellite networks or we need ne= w protocols? If we need new protocols, do such protocols exist?

Thanks
Hesha= m

On Sat, Mar 2, 2024, 7:18 AM Sebastian Moeller <moeller0@gmx=2Ede> wrote:
Hi Hesham

> On 2=2E Mar 2024, at 16:03, Hesham ElBakoury via Starlink <starlink@lists=2Ebufferbloat=2Enet> wrote:
>
> Time synchronization, for satellite networks, faces several challenge= s:
> 1=2E Signal Propagation Delays: Unlike terrestrial networks where sig= nals travel through cables at the speed of light,

[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=2E

> satellite communication involves signals traveling vast distances thr= ough space=2E This creates significant delays=2E

[SM] Sure distances might be larger, but propagation speed is around 10000= 0Km/s faster=2E=2E=2E my main point is speed of light is a) dependent on th= e medium b) not the things that differentiates space from the earth's surfa= ce here, but mere geometry and larger distances on larger spheres=2E=2E=2E<= br>
> 2=2E Clock Drift: Even highly precise atomic clocks, used in satellit= es, are susceptible to "drift" - gradually losing or gaining time=2E This d= rift, caused by factors like temperature variations, radiation exposure, an= d power fluctuations, can lead to inconsistencies in timekeeping across the= network=2E
> 3=2E Signal Degradation: As signals travel through space, they can de= grade due to factors like atmospheric interference, ionospheric disturbance= s, and solar activity=2E This degradation can introduce noise and errors, i= mpacting the accuracy of time synchronization messages=2E
> 4=2E Limited Resources: Satellites have limited power and processing = capabilities=2E Implementing complex synchronization protocols can be resou= rce-intensive, requiring careful optimization to minimize their impact on o= ther functionalities=2E
> 5=2E Evolving Technologies: As satellite technologies and application= s continue to evolve, new challenges related to synchronization might emerg= e=2E For example, the integration of constellations with thousands of satel= lites poses unique synchronization challenges due to the sheer scale and co= mplexity of the network=2E
> These challenges necessitate the development of robust and efficient = time synchronization protocols for satellite networks and an integrated sat= ellite 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=2E
> Thanks
> Hesham
>
>
>
> _______________________________________________
> Starlink mailing list
> Starlink@lists=2Ebufferbloat=2Enet
> https://lists=2Ebufferbloat=2E= net/listinfo/starlink

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