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Annex 4 to Doc. AVC-22R
Annex 4 to Doc. AVC-22R


First Simplified Network Model


A small group meeting was held and the following approach was agreed;
   
1)	A single stage multiplex is assumed.

2)	The network is assumed to exhibit a cell loss/network load 
characteristics as shown in Appendix 1.  An example of this 
characteristics is shown in Appendix 2.

3)	The multiplex is assumed to have a maximum available bandwidth (CAP) of 
100 Mbit/s.

4)	Cell loss is assumed to be random.

5)	Each cell loss corresponds to 48 consecutive bytes of information being 
lost.


END

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Appendix 1 to Annex 4/Doc. AVC-22R


 CLR = exp(-n*K)     where CLR is the cell loss ratio.

   K = {a*ln(a/p)} + [(1-a)*ln{(1-a)/(1-p)}]

   a = CAP/(n*Peak)     Note: 0 < a < 1

 CAP = Maximum capacity of the multiplexer output in Mbit/s

   n = percentage of network loading   

		Note: n is the number of sources, 0 ƒ n … 100.  The illustration 
corresponds to the case of Mean = 1 Mbit/s. 

Peak = The maximum bit rate over simulation interval (measured on a per frame
       basis)

   p = Mean/Peak        Note: 0 ƒ p … 1

Mean = The average bit rate over simulation interval

  ln = log to basis "e"


END
Appendix 2 to Annex 4/Doc. AVC-22R