fractional time values in an integer Schedule

[Andre Costa]

Hi,

My question is about how to deal with the limitations of an integer time
step schedule in Swarm, although I am sure this is a generic simulation
issue for any discrete-event scheduling simulator.

In my simulation, I have some source nodes in a network (TCP-like) which
send out discrete packets, and the sources also update their source rates
x(t) (packets/timestep) according to an adaptive rule 

x(t+1) = x(t) +  k*F( ) 

where k is a "gain" parameter and F( ) is a function which returns an
integer.

Since x(t) is the number of packets which a source emits in one simulation
time step, then the this number must be an integer.

However, I need to have a fractional gain parameter, k, which may also 
be interpreted as a "learning rate". Currently, I am constrained to having
integer values of k, but even k=1 is way too large for my purposes
(oscillations, etc.)

If x(t) were to be defined as a FLOAT instead of an INT, then what
scheduling mechanism could deal with say, 2.5 packets per time step,
whilst still scheduling an integer (by necessity) number of dicrete
packets per timestep in some reasonable fashion ?

I have thought about defining say, 100 basic Swarm time steps to
represent 1 simulated time unit, and thus obtaining fractional values
which resolve to 1/100 of a simulated time unit, but some kind of binning
would still be required and I wonder if anybody knows of a better 
system....


thanks,
Andre Costa

---------------------------------------------------------------------
Andre Costa
Research Student

**
Attending Santa Fe Institute Summer School 
during June 00
email: address@hidden
**

Teletraffic Research Centre           Telephone: (08) 8303 3237
Department of Applied Mathematics     Fax:       (08) 8303 4395
University of Adelaide                Email:address@hidden
South Australia  5005
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