From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lang.hm (syn-045-059-245-186.biz.spectrum.com [45.59.245.186]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id D02AB3B29D for ; Wed, 5 Jun 2024 03:03:32 -0400 (EDT) Received: from dlang-mobile (unknown [10.2.3.133]) by mail.lang.hm (Postfix) with ESMTP id D28751D3DD1; Wed, 5 Jun 2024 00:03:31 -0700 (PDT) Date: Wed, 5 Jun 2024 00:03:31 -0700 (PDT) From: David Lang To: Sebastian Moeller cc: Mike Puchol , Mike Puchol via Starlink , Michael Richardson via Starlink In-Reply-To: <350685C2-FF39-4EE4-93A5-1BE6EE9AC6C7@gmx.de> Message-ID: References: <32AD770E-336E-4CF4-8B1B-8AE7353981CC@ieee.org> <9687.1717527495@obiwan.sandelman.ca> <1011428206.2534598.1717542074644@www.openxchange.eu> <350685C2-FF39-4EE4-93A5-1BE6EE9AC6C7@gmx.de> MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="===============1738146899724173572==" Subject: Re: [Starlink] SpaceX/Starlink says it's ready for a fall satellite-to-cell service with T-Mobile 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: Wed, 05 Jun 2024 07:03:32 -0000 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --===============1738146899724173572== Content-Type: text/plain; format=flowed; charset=US-ASCII Sebastian Moeller wrote: > Curious, is that doppler correction applied individually per dishy, or per > cell? If the latter do cells extend ahead or behind the satellite's projection > onto the globe, or is there one or more beams ahead an another one or more > behind? sorry, I was specifically talking about the direct-to-cell capability. In one of the early presentations, Elon mentioned that one of the problems was doppler shift and the need to correct for it in the satellite so that the phones on the ground see the same frequency that they would get from a normal cell tower. Since normal cell phones depend on timing signals from the tower, I am assuming that it's a single correction for the entire cell David Lang > On 5 June 2024 06:16:02 CEST, Mike Puchol via Starlink wrote: >> Yes, they correct doppler in a single stream - what I was alluding to is the MIMO advantage of terrestrial networks which cannot be easily replicated from multiple satellites, as the UE cannot correct multiple doppler shifts and timing advances unless it implements an NTN-specific approach. >> >> Best, >> >> Mike >> On Jun 4, 2024 at 20:17 -0700, David Lang , wrote: >>> Mike Puchol wrote: >>> >>>> Something else that's much harder to implement is MIMO, as you don't get path >>>> diversity from a satellite. AST claims they will do this by using more than >>>> one satellite, however they haven't answered basic questions such as how will >>>> the UE compensate the huge differences in doppler shift on top of the multiple >>>> paths. >>> >>> for the starlink version, the satellite adjusts it's transmit/receive >>> frequencies to correct for the doppler shift so that the phones don't need to. >>> >>> David Lang >>> > > --===============1738146899724173572== Content-Type: text/plain; CHARSET=utf-8 Content-Transfer-Encoding: BASE64 Content-ID: Content-Description: Content-Disposition: INLINE X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KU3Rhcmxpbmsg bWFpbGluZyBsaXN0ClN0YXJsaW5rQGxpc3RzLmJ1ZmZlcmJsb2F0Lm5ldApodHRwczovL2xpc3Rz LmJ1ZmZlcmJsb2F0Lm5ldC9saXN0aW5mby9zdGFybGluawo= --===============1738146899724173572==--