Re: [Starlink] System and method of providing a medium access control scheduler

[Oleg Kutkov <contact@olegkutkov.me>]

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It's 20 km in diameter, roughly.

On 2/24/23 02:51, Ulrich Speidel via Starlink wrote:
>
> Did you mean to say 20 km diameter or 20 km^2 area?
>
> For those not familiar with RF engineering terms: A 3 dB contour as 
> Oleg shows it below in blue is the line where the power flux density 
> from the satellite drops to half of the value at the centre of the 
> beam. That's important as in RF engineering of cellular or beam 
> division networks, the minimum power you need to receive a signal 
> successfully can be several orders of magnitude larger than the amount 
> of power you need to cause interference to off-beam unintended 
> receivers. So in terms of their interference contour, beams are 
> actually much wider than just a cell or so, and a power flux density 
> half as high as at beam centre doesn't mean that it's the perimeter of 
> the beam as such - the beam will happily interfere with anyone up to a 
> few cells down the road at least.
>
> Incidentally, I'm seeing Dishy use more power when it's receiving at 
> higher rates, which is what you'd expect if its DSP is busy digging 
> out intended signals from unintended ones.
>
> On 24/02/2023 1:18 pm, Oleg Kutkov via Starlink wrote:
>>
>> Yes. The cell size is ~20 km
>>
>> On 2/24/23 02:08, David Lang wrote:
>>> they can only narrow the radio beam so much (probably whatever their 
>>> cell size is). They can't change the footprint without changing the 
>>> antenna, so unless they have the beam move around in the cell, the 
>>> footprint should be slightly larger than the cell size
>>>
>>> sometimes there is a lot of data going to one station, but sometims 
>>> it's only going to be a trival amount (think ack packets for a lot 
>>> of uploads), so they can save airtime by using one timeslot to 
>>> transmit to many stations at once.
>>>
>>> David Lang
>>>
>>> On Fri, 24 Feb 2023, Oleg Kutkov via Starlink wrote:
>>>
>>>> Date: Fri, 24 Feb 2023 01:47:05 +0200
>>>> From: Oleg Kutkov via Starlink <starlink@lists.bufferbloat.net>
>>>> Reply-To: Oleg Kutkov <contact@olegkutkov.me>
>>>> To: starlink@lists.bufferbloat.net
>>>> Subject: Re: [Starlink] System and method of providing a medium 
>>>> access control
>>>>      scheduler
>>>>
>>>> Oh, that's interesting.
>>>>
>>>> >> the satellite broadcasts the downlink radio frame to all the 
>>>> user terminals in a group and they each retrieve their respective 
>>>> data from the downlink radio frame
>>>>
>>>> I thought the satellite beamformer only sends data frames to the 
>>>> appropriate UT. It looks like the given satellite covers the whole 
>>>> cell at one TX channel.
>>>> Otherwise, it would be too complex, I guess.
>>>>
>>>> On 2/23/23 23:53, Dave Taht via Starlink wrote:
>>>>> For those of you that don't look at patents, don't look at:
>>>>>
>>>>> https://patents.justia.com/patent/11540301
>>>>>
>>>>> But I would welcome comment from those that do.
>>>>>
>>>>> H/T virtuallynathan.
>>>>>
>>>>
>> -- 
>> Best regards,
>> Oleg Kutkov
>>
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>> https://lists.bufferbloat.net/listinfo/starlink
>>
> -- 
> ****************************************************************
> Dr. Ulrich Speidel
>
> School of Computer Science
>
> Room 303S.594 (City Campus)
>
> The University of Auckland
> u.speidel@auckland.ac.nz  
> http://www.cs.auckland.ac.nz/~ulrich/
> ****************************************************************
>
>
>
>
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-- 
Best regards,
Oleg Kutkov

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