But what I was asking is - are my assumptions correct ?

The call flow looks like this [I have skipped some equipment] :

        

      ?                2E1                                               3.6 mbps

MS--------->RBS--------------->radio link----------------->GPRS------------------->Internet

     ?                  2E1                                               3.6 mbps

MS<---------RBS<--------------radio link<----------------GPRS<-------------------Internet


So, when calculating bandwidth for an end user - several possible calculations arise - assuming the RBS has 3 cells


1) take the two E1s to mean that - 1 is for download, the other is for upload [when there is no congestion]

End user will receive = 64kbps * 31 timeslots = 1.984 mbps [not explicitly cos 1mb=1024]

But end user is getting a high of 1.6 mbps here - why ?


2) take the two E1s to be shared for both down and upload

End user will receive = 64kbps * 31 timeslots * 2 = 3.968 mbps [not explicitly cos 1mb=1024]

End user is getting 1.6 mbps because its same scenario or position as the above


3) take that the E1 is divided amongst the 3 cells on an RBS to serve on demand - -and if 1E1 is used for download and the other for upload.

So assuming one cell has no user:

a)
2/3  * 64 kbps * 31 timeslots =  1.3 mbps

or if each cells have at least 1 user

b)
1/3 * 64 kbps * 31 timeslots = 661 kbps

4) take the two E1s to be shared for both down and upload and is divided for 3 cells of the RBS

So assuming one cell has no user:

a)
2/3  * 64 kbps * 31 timeslots * 2 =  2.6 mbps

or if each cells have at least 1 user

b)
1/3 * 64 kbps * 31 timeslots * 2  = 1.32 mbps

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From the above results - the results in red are an approximate of what we are getting on the ground.

However, I need to come up with a comprehensive and "almost" true way to calculate the above, in-order to advise appropriately.


So based on your experiences, which is the right way to calculate - out of the 4 methods ?
These are also microwave links, so take it as same scenario.

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How will the increase in users affect these calculations of bandwidth ?

I still do not understand the concept of a "dedicated link" when it comes to user distribution - in retrospect - if the customer is getting 3.6 mbps from ISP and he is to distribute to mobile users - are the users really supposed to get 3.6 mbps each - or will this now be divided by the number of active users?

Because in theory, each of these users has this 4mbps capable on his 3G/HSDPA card for radio link- and each user has a 3.6 mbps dedicated link to internet on the operator's side.

so:

is it:
         4mbps                   3.6mbps
user ----------->radio------------------->intenet


or is it

         4mbps          [3.6mbps divided by no. of users]
user------------>radio------------------->internet

And how does uplink and downlink separate channels to internet affect this ?

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I know its a long question - sorry for the time and length.

w/r
Stephen N.