Method of and a system for estimating the frequency uncertainty of a mobile radio system able to use two different mobile radio networks

• US 20030008621A1
• Filed: 06/25/2002
• Published: 01/09/2003
• Est. Priority Date: 06/28/2001
• Status: Active Grant

• Current Assignee: DRNC Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Rouvellou, Laurent
• Granted Patent: US 6,934,559 B2
• Time in Patent Office: Days
• US Class Current: 455/67.11
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

In a method of estimating the relative frequency uncertainty between two parts of a mobile radio system able to communicate via two mobile radio networks at first and second particular frequencies, each part of the mobile radio system has a clock from which the particular frequency is derived and the uncertainty is estimated by measuring the number of pulses of each of the clocks during a time window of duration T starting at a time t. The method includes the following steps, with the time window T sliding:

a) measuring the number of pulses of each of the clocks at n intermediate times t+(T/n), t+(2T/n), . . . , t+(nT/n), where n is a positive integer,

b) storing the numbers of clock pulses thereby obtained in memory,

c) calculating the relative frequency uncertainty at time t+T from the numbers of clock pulses stored in memory.

Claims

1. A method of estimating the relative frequency uncertainty between a part of a mobile radio system able to communicate via a first mobile radio network at a first particular frequency and another part of the same mobile radio system able to communicate via a second mobile radio network at a second particular frequency, in which method each part of said mobile radio system has a clock from which said particular frequency is derived and said uncertainty is estimated by measuring the number of pulses of each of said clocks during a time window of duration T starting at a time t, and which method includes the following steps:

a) measuring the number of pulses of each of said clocks at n intermediate times t+(T/n), t+(2T/n), . . . , t+(nT/n), where n is a positive integer,

b) storing the numbers of clock pulses thereby obtained in memory,

c) calculating the relative frequency uncertainty at time t+T from said numbers of clock pulses stored in memory, and

d) iterating steps a) and b) at times t′

, where the difference between two consecutive times t′

is less than T, and with said time window of duration T sliding to obtain said uncertainty at any time t′

.

2. The method claimed in claim 1 wherein the difference between two consecutive times t′

is of the order of T/n.

3. The method claimed in claim 1 wherein the duration of measuring said numbers of pulses at said intermediate times is of the order of T/n.

4. The method claimed in claim 1 wherein the duration T of said time window induces a relative frequency uncertainty error and said step c) further includes the following steps:

estimating the evolution of said uncertainty over said time window T from said numbers of clock pulses measured at said intermediate times and stored in memory,

calculating said uncertainty error from said evolution, and

correcting said uncertainty as a function of said error.

5. The method claimed in claim 1 wherein T is of the order of 1 second.

6. The method claimed in claim 1 wherein said measurements of the numbers of clock pulses obtained are completed by interpolation.

7. A mobile radio system having a first part able to communicate via a first mobile radio network at a first particular frequency and a second part able to communicate via a second mobile radio network at a second particular frequency, in which system each part has a clock from which said particular frequency is derived and which system further includes a system for measuring the number of pulses of each of said clocks and a program memory containing a program for implementing a method as claimed in any preceding claim.

8. A mobile radio system having a first part able to communicate via a first mobile radio network at a first particular frequency and a second part able to communicate via a second mobile radio network at a second particular frequency, in which system each part has a clock from which said particular frequency is derived and which system further includes a system for measuring the number of pulses of each of said clocks during a time window of duration T starting at a time t, a calculator unit, and a memory for storing the numbers of clock pulses measured at intermediate times t+(T/n), t+(2T/n), . . . , t+(nT/n).

9. The system claimed in claim 8 wherein said memory is a FIFO memory.

10. The system claimed in claim 8 further including a unit for estimating the error resulting from the duration T of said time window.