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# File Transfer Time Computation

IP.com Disclosure Number: IPCOM000125380D
Original Publication Date: 2005-May-31
Included in the Prior Art Database: 2005-May-31
Document File: 2 page(s) / 60K

IBM

## Abstract

When transferring a (large) file, the estimation of the time which is necessary to do the transfer is generally not accurate, and the accuracy of the estimation doesnâ€™t improve as transfer goes. The present publication proposes an accurate estimation taking into account the current line throughput while smoothing peak rates as they occur.

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File Transfer Time Computation

Usually, file transfer time estimation is only based on the instantaneous bit rate. As the bit rate varies a lot during the data transfer, the computed remaining time dramatically alters, leading to a useless estimation of the transfer time. A typical method for estimating the data transfer time is to use Kalman filters. The present publication discloses a simple method, based on the average bit rates during transfer. This method gives better results than traditional methods.

The transfer time is estimated at every time step (let say 1 second) from the begining of file transfer.

Traditional methods of estimating the remaining time for tranfering files are based on the following formula : transfer_time (t) = bytes_to_be_transferred(t) / measured_byte_rate(t)

The present method is based on the following formula :

T(k) = B(k) / E_A(k)

where :

T : estimated transfer time left
B : bytes left to transfer
E_A : estimated final average transfer time

To estimate the final average transfer time (E_A), Kalman filters can be used (it is a classic way to solve estimation problems)

A simple example is to take the average bit rate:

E_A(k) = A(k) = 1/k . Sum ( I(j) , j=0..k-1 )

I : instantaneous line speed (measured every second for instance) A : average line speed (computed every second for instance)

The following graphics show the difference between the two methods for estimating the remaining time during a file transfer. Two cases have been consid...