Method for analysing the operation of a packet data transmission network interface

• US 20050002394A1
• Filed: 06/14/2004
• Published: 01/06/2005
• Est. Priority Date: 06/12/2003
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Baynat, Bruno, Eisenmann, Pierre, Rached, Nidham Ben
• Application Number:
  US10/869,612
• Publication Number:
  US 20050002394A1
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04W 16/22 Traffic simulation tools or models
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

The invention aims to analyse the operation of an interface of a packet data transmission network comprising terminals capable of exchanging data in packets with at least one entity of the network via at least one base station over the said network interface. For a set of integers n, the probability S(n) that a number n of terminals exchange data with at least one base station during an elementary transmission time interval is estimated.

Claims

1. Method for analysing the operation of an interface of a packet data transmission network comprising terminals capable of exchanging data in packets with at least one entity of the network via at least one base station over the said network interface, wherein, for a set of integers n, the probability S(n) that a number n of terminals exchange data with at least one base station during an elementary transmission time interval is estimated.

2. Method according to claim 1, in which the data exchanges over the said interface include successive periods of downloading and periods of silence, each download containing a quantity of data exchanged over the said network interface with a geometric distribution, and the periods of silence having a duration with a geometric distribution, and in which method each probability S(n) is calculated using a memoryless Markov process.

3. Method according to claim 2, in which each probability S(n) is calculated according to the expression:

$S<br><br>\left(n\right)=\underset{i=1}{\overset{n}{\prod <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{a_1^{i-1}<br><br>d_0^{i-1}}{a_0^i<br><br>d_1^i}·<br><br>S<br><br>\left(0\right),$

where S(0) is of the form;

$S<br><br>\left(0\right)=\frac{1}{1+\underset{i=1}{\overset{n<br><br>\text{\hspace{1em}<br><br>}<br><br>\max }{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left[\underset{i=1}{\overset{n}{\prod <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{a_1^{i-1}<br><br>d_0^{i-1}}{a_0^i<br><br>d_1^i}\right]},$

a₁ⁱ and d₁ⁱ representing, for integer i, the probability of a period of downloading and a period of silence, respectively, starting between two successive elementary transmission time intervals when i terminals exchange data with the said base station, a₀ⁱ and d₀ⁱ representing the probability of there being no start of a period of downloading and a period of silence, respectively, between two successive elementary transmission time intervals when i terminals exchange data with the said base station, and n_max representing a maximum number of terminals.

4. Method according to claim 2, in which each probability S(n) is calculated according to the expression:

$S<br><br>\left(n\right)=\underset{i=1}{\overset{n}{\prod <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\left[N-\left(i-1\right)\right]·<br><br>q·<br><br>\left[1-p·<br><br>\min <br><br>\left(\left(i-1\right)·<br><br>d,T\right)\right]}{\left[1-\left(N-i\right)·<br><br>q\right]·<br><br>p·<br><br>\min <br><br>\left(i·<br><br>d,T\right)}·<br><br>S<br><br>\left(0\right),$

where S(0) is of the form;

$S<br><br>\left(0\right)=\frac{1}{1+\underset{i=1}{\overset{\mathrm{nmax}}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{l=1}{\overset{n}{\prod <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{\left[N-\left(i-1\right)\right]·<br><br>q·<br><br>\left[1-p·<br><br>\min <br><br>\left(\left(i-1\right)·<br><br>d,T\right)\right]}{\left[1-\left(N-i\right)·<br><br>q\right]·<br><br>p·<br><br>\min <br><br>\left(i·<br><br>d,T\right)}}$

N being a number of terminals that can exchange data with the said base station, n_max representing a maximum number of terminals, q representing the probability that a period of silence is completed after the said elementary transmission time interval, p representing the probability that a period of downloading is completed after the said elementary transmission time interval, d representing a number of resources used by the terminals when they exchange data with the said base station, and T representing a maximum number of resources for the data exchanges between terminals and the said base station.

5. Method according to claim 2, in which each probability S(n) is calculated according to:

$\begin{array}{c}S<br><br>\left(n\right)=<br><br>\frac{N!}{n!<br><br>d^n<br><br>\left(N-n\right)!}<br><br>{\left(\frac{q}{n}\right)}^n<br><br>S<br><br>\left(0\right),\mathrm{when}<br><br>\text{\hspace{1em}<br><br>}<br><br>n\le <br><br>n_0,\\ \mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>S\left(n\right)=<br><br>\frac{N!}{n_0!<br><br>d^{n_0}<br><br>T^{n-n_0}<br><br>\left(N-n\right)!}<br><br>{\left(\frac{q}{n}\right)}^n<br><br>S<br><br>\left(0\right),\mathrm{when}<br><br>\text{\hspace{1em}<br><br>}<br><br>n><br><br>n_0,\mathrm{where}\\ S<br><br>\left(0\right)=<br><br>\frac{1}{1+\left[\underset{n=1}{\overset{n_0}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{N!}{n!<br><br>d^n<br><br>\left(N-n\right)!}<br><br>{\left(\frac{q}{n}\right)}^n+\underset{n=n_0+1}{\overset{n_{\max }}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{N!}{n_0!<br><br>d^{n_0}<br><br>T^{n-n_0}<br><br>\left(N-n\right)!}<br><br>{\left(\frac{q}{p}\right)}^n\right]},\end{array}$

N being a number of terminals that can exchange data with the said base station, n_max representing a maximum number of terminals, q representing the probability that a period of silence is completed after the said elementary transmission time interval, p representing the probability that a period of downloading is completed after the said elementary transmission time interval, d representing a number of resources used by the terminals when they exchange data with the said base station, T represents a maximum number of resources for the data exchanges between terminals and the said base station and no representing a number of terminals exchanging data with the said base station whenever the said T resources are all being used.

6. Method according to claim 4, in which p may be written as

$p=\frac{1}{\lceil }$

x on x B ⌉

,

and q may be written as

$q=\frac{1}{\lceil <br><br>\frac{t_{\mathrm{off}}}{t_B}\rceil <br><br>},$

where x_on is a mean quantity of data exchanged between terminals and the said base station, x_B is a quantity of data transferred during an elementary transmission time interval t_B, and t_off is a mean duration of a period of silence.

7. Method according to claim 5, in which p may be written as

$p=\frac{1}{\lceil }$

x on x B ⌉

,

and q may be written as

$q=\frac{1}{\lceil <br><br>\frac{t_{\mathrm{off}}}{t_B}\rceil <br><br>},$

where x_on is a mean quantity of data exchanged between terminals and the said base station, x_B is a quantity of data transferred during an elementary transmission time interval t_B, and t_off is a mean duration of a period of silence.

8. Method according to claim 1, in which the data exchanges are carried out from the base station to at least certain of the said terminals.

9. Method according to claim 1, in which the said network interface is a radio interface.

10. Method according to claim 9, in which the said radio interface is of the GPRS (“

General Packet Radio Service”

), EDGE (“

Enhanced Data rates for GSM Evolution”

) or UMTS (“

Universal Mobile Telecommunication System”

in packet mode type.

11. Method according to claim 1, in which the probability S(n) is estimated repeatedly at successive instants.

12. Method according to claim 11, including a subsequent step of deducing performance indicators relating to the said network interface from the determined probabilities S(n).

13. Method according to claim 12, in which the performance indicators relating to the said network interface are at least certain from among:

a distribution of data rates relating to the data exchanges, a distribution of blocking rates and a distribution of resource utilization for the data exchanges.

14. Method according claim 12, in which an exploitation of at least certain of the performance indicators is carried out.

15. Method according to claim 14, in which the exploitation of the performance indicators comprises combining at least certain of the said performance indicators and comparing the combined indicators with respective thresholds, in order to supervise the said network interface.

16. Method according to claim 14, in which the exploitation of the performance indicators comprises taking at least certain of the said performance indicators into account in a mechanism for allocating the resources to the said network interface.

17. Method according to claim 14, in which the exploitation of the performance indicators comprises taking at least certain of the said performance indicators into account in order to dimension the network interface, the dimensioning of the said network interface comprising a selection of assumptions from among various assumptions with regard to the number of resources for the data exchanges and the number of terminals that can exchange data with the network, on the basis of the performance indicators obtained for the various assumptions.

18. A packet control unit on an interface of a packet data transmission network comprising terminals capable of exchanging data in packets with at least one entity of the network via at least one base station over the said network interface, said packet control unit comprising means for estimating, for a set of integers n, the probability S(n) that a number n of terminals exchange data with at least one base station during an elementary transmission time interval.

19. Packet control unit according to claim 18, in which the means for estimating the probability S(n) comprise means for estimating a mean proportion of time during which a number n of terminals exchange data with at least one base station during an elementary transmission time interval.

20. Packet control unit according to claim 18, which furthermore includes means for counting, over at least one observation period, an integer number x(n) of elementary transmission time intervals during which n terminals exchange data with at least one base station, in which packet control unit the means for estimating the probability S(n) estimate the probability S(n) according to the expression:

$S<br><br>\left(n\right)=\frac{x<br><br>\left(n\right)}{\underset{i=0}{\overset{n_{\max }}{\sum <br><br>}}<br><br>x<br><br>\left(i\right)},$

where n_max denotes a maximum number of terminals.

21. Packet control unit according to claim 18, in which the means for estimating the probability S(n) comprise means for updating the probability S(n) at each new observation period.

22. Packet control unit according to claim 18, in which the said network interface is a radio interface.

23. Packet control unit according to claim 22, in which the said radio interface is of the GPRS (“

General Packet Radio Service”

), EDGE (“

Enhanced Data rates for GSM Evolution”

) or UMTS (“

Universal Mobile Telecommunication Systems”

)in packet mode type.

24. Packet control unit according to claim 18, comprising means for obtaining performance indicators relating to the said network interface from the probabilities S(n) that are estimated by the said means for estimating the probability S(n).

25. Packet control unit according to claim 24, in which the performance indicators relating to the said network interface are at least certain from among:

a distribution of data rates relating to the data exchanges, a distribution of blocking rates and a distribution of resource utilization for the data exchanges.

26. Packet control unit according to claim 24, comprising means for allocating resources for the data exchanges between terminals and at least one base station, taking at least certain of the said performance indicators into account.