From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from vsmx002.dclux.xion.oxcs.net (vsmx002.dclux.xion.oxcs.net [185.74.65.108]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id F0A203B29D for ; Wed, 5 Jun 2024 00:16:14 -0400 (EDT) Received: from proxy-3.proxy.shared.ns.xion.oxcs.net (proxy-3.proxy.shared.ns.xion.oxcs.net [73.162.31.53]) by mx-out.dclux.xion.oxcs.net (Postfix) with ESMTPA id 5E193A608AD for ; Wed, 5 Jun 2024 04:16:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dclux.xion.oxcs.net; s=mail1; t=1717560973; bh=JDyRB9XPuWG3PAw9H4cerjJlBjwC/BLPXgvF+2nAz2w=; h=Date:From:To:Cc:In-Reply-To:References:Subject:From; b=Rwa8SKYtqpAxVST5WvEGq2+K4/JMwirFpbGL1H69xsyUJuKgx+tQBcu3nildMhl/q pzEHiESEIfrdbAfXpbfVvmNXVuQOMZUBaSnsqbGkhI/9zF7Rf83OaivXRGo9ULgdvD 0KjwcpEWyem5DRNxGJaA4EsJtez3/hH+usFNsSaATzPtxgKlo31rpWkd5mdBoD9DiF HJ8AdpDz4L18Yy/dVr4/3eDAVC0qgpGuFhVAGpdb/jZ6l3nlDhEqEBMnSwLhAytghk Xj5flyStXLlqgh+Sx2Rj8xLdd75UKTguLIF4iNR7e7mbZ4T/iiMhf/tF9ZyINf3mcV bS+nITn+QmFsw== Date: Tue, 4 Jun 2024 21:16:02 -0700 From: Mike Puchol To: Michael Richardson via Starlink Cc: Michael Richardson via Starlink Message-ID: In-Reply-To: References: <32AD770E-336E-4CF4-8B1B-8AE7353981CC@ieee.org> <9687.1717527495@obiwan.sandelman.ca> <1011428206.2534598.1717542074644@www.openxchange.eu> X-Readdle-Message-ID: e8a6c3fe-7bd1-4cc9-b80b-bce636e21656@Spark MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="665fe689_4e79aa8_d3a8" X-VadeSecure-Status: LEGIT X-VADE-STATUS: LEGIT 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 04:16:15 -0000 --665fe689_4e79aa8_d3a8 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline 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 > --665fe689_4e79aa8_d3a8 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Yes, they cor= rect doppler in a single stream - what I was alluding to is the MIMO adva= ntage of terrestrial networks which cannot be easily replicated from mult= iple satellites, as the UE cannot correct multiple doppler shifts and tim= ing advances unless it implements an NTN-specific approach.

Best,

Mike
On Jun 4, 2024 at 20:17 -0700, Davi= d Lang <david=40lang.hm>, wrote:
Mike Puchol wrote:

Something else that's much harder to implem= ent is MIMO, as you don't get path
diversity from a satellite. AST claims they will do this by using more th= an
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 mul= tiple
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 nee= d to.

David Lang

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