Mike Puchol 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.

I am thinking that the doppler correction will be the same (or very close to it) 
for everything in a single cell.

now, timing that exact between multiple satellites is something I would see as a 
harder problem, but I'm not an expert there.

David Lang

>
> Best,
>
> Mike
> On Jun 4, 2024 at 20:17 -0700, David Lang <david@lang.hm>, 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
>>
>