Re: [Starlink] SpaceX/Starlink says it's ready for a fall satellite-to-cell service with T-Mobile

[Mike Puchol <mike@starlink.sx>]

There are certain resource-saving techniques that cannot be used in the DTC service, such as Location Area (LA). In terrestrial networks, an LA groups several cells, and as long as the UE is able to listen to pages from a cell in the same LA, it does not need to re-attach each time it roams to a different cell.

This was a big saver years ago, today with 4G/LTE and 5G, most UEs are constantly doing something in the background, and there isn't much gain from LA use. 

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.

One other resource waste is the need to trick the device to overcome timing advance - effectively transmissions are blindly ACK'd by the satellite in the hopes they will go through, increasing the protocol overhead.

What I did always notice when I traveled to e.g. Kenya was that the lower density of cells caused my phone to consume its battery a lot quicker than in e.g. Europe. With DTC, the UE is always going to be at the edge of the cell, transmitting at maximum power, so the main use case is low data rate messaging and emergencies IMHO.

Best,

Mike


> On 04/06/2024 20:58 CEST Michael Richardson via Starlink <starlink@lists.bufferbloat.net> wrote:
> 
>  
> Eugene Y Chang via Starlink <starlink@lists.bufferbloat.net> wrote:
>     > I observe a difference in my phone’s batter life between urban and
>     > rural usage. I expect the battery life to be significantly reduced with
>     > Starlink.  And yes… if the phone isn’t communicating then the battery
> 
> Sure, but if my phone is plugged into my car, and it's sitting on the
> dashboard, that still seems like a win to me.
> (Except for people who were hoping to unplug their kids by going camping)
> 
> The service across northern ontario, along the Trans-Canada is still very
> poor (okay, I was last there in 2018).
> 
> -- 
> Michael Richardson <mcr+IETF@sandelman.ca>   . o O ( IPv6 IøT consulting )
>            Sandelman Software Works Inc, Ottawa and Worldwide
> 
> 
> 
> 
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