Browse Prior Art Database

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

Publishing Venue

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 doesn’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...