From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id D84A93CB37 for ; Sat, 2 Mar 2024 10:26:13 -0500 (EST) Received: by mail-pf1-x433.google.com with SMTP id d2e1a72fcca58-6e6092a84f4so30634b3a.0 for ; Sat, 02 Mar 2024 07:26:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1709393172; x=1709997972; darn=lists.bufferbloat.net; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=dZcWhNQMjs50o3gAElPyeBFbsa7HTbPmvK2vFn08y9I=; b=KaS6rLxiaceovfgvXp7F+zyeW2U6RDDh5xUAyZst/NtY7fWDF+/yj9pzZPoxleWQU3 6cKsS5CRndK+h02O3rhJX1GAKM6OAP8WlZALDoNuQMYz9VSZpsWSYXDeNmOk9/S3byGT /0jA7bGp5Dlu2hfBmCoRZ51p6pYBLpfCD0DPIlq441dM7ThSP7XhEG0bHkLl4wqjPlgn kY4t0A+8t9WC7xVxdKTDZvwouztkSADCrRzJCOl9avBR5Ihpa/AIx+GhM3wsdzI4klQ1 76SqJ7TkEZFhTRQ7Rv1gfPjkjCAUYaJIVjbRZHV0KSCkjlrjVzRd294GFo76iEANUzLJ vk1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709393172; x=1709997972; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=dZcWhNQMjs50o3gAElPyeBFbsa7HTbPmvK2vFn08y9I=; b=f+b0UKo2kR6CasvA3rKAVhfMVthQ6E5NbGHLr0WU7PxdIdbsHjp3IlQ0GvK1mvnA1w wHC/UP4xKGeiaR5cLaCpuHh8CP37EGh47ZB6pEMg6B6DprpFJPd+zG9imdI6jja9Y6Vt QMsNkymke6Hd+UEdG9TJLI0uDLXMNk5Y1C5ec0yT+nknSVT4umVRFx961Ri5/7O2z4w8 dwnBRsD4m8KKARfqZOdKgmxMGzVJK+ZElI4EIdZwPMv3r+rSMn+syKBhgZKK5tq6s1fb hHJ0NLw5JBDg89JU/AWd7PqWQzO3Zd+HpCsqdXy+0dsubTmT/9CyQTLgM8J0pqPUf2MT dewQ== X-Gm-Message-State: AOJu0YzbIPYKQo0UsQNGIQHbwsfyQfUfWeXJNa+j70q/es+oUSSrxHo/ Cvrok/7ik8dsOVUjoSX+/b13iKsIF0hUHMeRNGsJkDY9DhLW7gHU1km+WiY3J20Kt4zIhI4cvgf TG6ommplwJUn2Gm4g/GpKzBHNI0rafAR8 X-Google-Smtp-Source: AGHT+IFrKTRhWjyanVaIEFjTQMsPgxE79p7txuGbM57cDdBEe8ivdUT4xVIabPMtWGS5eWiKAkyaUvKX5UCTGUQTZBk= X-Received: by 2002:a05:6a21:339b:b0:1a0:f096:502d with SMTP id yy27-20020a056a21339b00b001a0f096502dmr4593841pzb.22.1709393172448; Sat, 02 Mar 2024 07:26:12 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Hesham ElBakoury Date: Sat, 2 Mar 2024 07:25:59 -0800 Message-ID: To: Sebastian Moeller Cc: Dave Taht via Starlink Content-Type: multipart/alternative; boundary="000000000000d34fa60612af1c4f" 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 15:26:14 -0000 --000000000000d34fa60612af1c4f Content-Type: text/plain; charset="UTF-8" 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. Mar 2024, at 16:03, Hesham ElBakoury via Starlink < > starlink@lists.bufferbloat.net> wrote: > > > > 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, > > [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. > > > satellite communication involves signals traveling vast distances > through space. This creates significant delays. > > [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... > > > 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. > > 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 > > > > > > > > _______________________________________________ > > Starlink mailing list > > Starlink@lists.bufferbloat.net > > https://lists.bufferbloat.net/listinfo/starlink > > --000000000000d34fa60612af1c4f Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi=C2=A0Sebastian,
Can we still use PTP = and NTP for time synchronization in=C2=A0 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 <moeller0@gmx.de> wrote:
Hi Hesham

> On 2. Mar 2024, at 16:03, Hesham ElBakoury via Starlink <starlink@lists.bufferbloat.net> wrote:
>
> Time synchronization, for satellite networks, faces several challenges= :
> 1. Signal Propagation Delays: Unlike terrestrial networks where signal= s travel through cables at the speed of light,

[SM] The speed of light in your typical glas fibers (and accidentally the i= nformation 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 l= evel is a mere 90 KM/s slower than in vacuum.

> satellite communication involves signals traveling vast distances thro= ugh space. This creates significant delays.

[SM] Sure distances might be larger, but propagation speed is around 100000= Km/s faster... my main point is speed of light is a) dependent on the mediu= m b) not the things that differentiates space from the earth's surface = here, but mere geometry and larger distances on larger spheres...

> 2. Clock Drift: Even highly precise atomic clocks, used in satellites,= are susceptible to "drift" - gradually losing or gaining time. T= his drift, caused by factors like temperature variations, radiation exposur= e, and power fluctuations, can lead to inconsistencies in timekeeping acros= s the network.
> 3. Signal Degradation: As signals travel through space, they can degra= de due to factors like atmospheric interference, ionospheric disturbances, = and solar activity. This degradation can introduce noise and errors, impact= ing the accuracy of time synchronization messages.
> 4. Limited Resources: Satellites have limited power and processing cap= abilities. Implementing complex synchronization protocols can be resource-i= ntensive, requiring careful optimization to minimize their impact on other = functionalities.
> 5. Evolving Technologies: As satellite technologies and applications c= ontinue 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 complex= ity of the network.
> These challenges necessitate the development of robust and efficient t= ime synchronization protocols for satellite networks and an integrated sate= llite and=C2=A0 terrestrial networks
> Are you aware of such time synchronization protocols?
> I would think that using Satellite simulators is the most viable way t= o develop and test these protocols given that using satellites is not that = easy.
> Thanks
> Hesham
>
>
>
> _______________________________________________
> Starlink mailing list
> Starlink@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinf= o/starlink

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