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Author Topic: Three - couple of questions about traffic engineering  (Read 1170 times)


  • Reg Member
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  • Posts: 415
Re: Three - couple of questions about traffic engineering
« Reply #15 on: October 08, 2020, 02:20:25 PM »

2 x 5mhz allocations:

Site that gives far more detail, though 3 now support Carrier Aggregation of B3+B20, and B32, etc, not just B1+B3:


  • Kitizen
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Re: Three - couple of questions about traffic engineering
« Reply #16 on: October 08, 2020, 04:31:56 PM »

Cheers, I wonder if they use the two bands as alternatives in different places.  My router just says 5MHz and the cell information says
Bandwidth*   5 MHz
Uplink Frequency   834.5 MHz
Downlink Frequency   793.5 MHz



  • Kitizen
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  • Random network numpty
Re: Three - couple of questions about traffic engineering
« Reply #17 on: October 09, 2020, 03:05:07 PM »

I wonder whether anyone can answer either of these questions. 

Firstly on 4G our data rates both up and down vary from time to time.  So for the upload directing in particular I was wondering whether this rate is actually visible to the router, for example if the rate is 9 meg does that mean the router is actually transmitting at no more than 9 meg, or could it be transmitting at a higher rate with the limit applying somewhere with the network.


Looking at that Cellmapper page it seems to depend on modulation as well, and as far as I understand that is negotiated on the fly.

Missed these.

The amount of spectrum you're provided, LTE uses frequency division on the uplink, depends on your data requirements so it constantly varies. There's a scheduler that in concert with your device works out an allocation then provides it dynamically.

The modulation order and, hence, efficiency, also change depending on conditions. Can be 2 or 4 bits per Hz with 6 bits per Hz optional on uplink.

With these in mind there's no way for the device to know what the bandwidth is until the cell tower has informed it of its upstream frequency allocation during that period alongside the modulation order to use for that burst.
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