Device and method for detecting pilot PN offset in cordless telephone system

• US 6,567,460 B1
• Filed: 05/05/1998
• Issued: 05/20/2003
• Est. Priority Date: 05/15/1997
• Status: Expired due to Fees

• Current Assignee: LG Information & Communications Ltd. (LG Corporation)
• Original Assignee: LG Information & Communications Ltd. (LG Corporation)
• Inventors: Tak, Yong Sang, Kim, Dae Hyun
• Primary Examiner(s): DEPPE, BETSY LEE
• Application Number:
  US09/072,352
• Time in Patent Office: 1,841 Days
• Field of Search: 375/130, 375/140, 375/142, 375/143, 375/145, 375/147, 375/149, 375/150, 375/152, 375/367, 370/320, 370/335, 370/342, 370/441, 370/503, 370/509, 370/515, 379/185, 455/422, 455/462, 455/463, 455/434, 455/552
• US Class Current: 375/140
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04W 16/16 for PBS [Private Base Station] arrangements

Abstract

A device and method for detecting a pilot PN offset in a cordless telephone system is disclosed. The device and method can detect all pilot PN offsets within a service region of the home station for detecting and providing a pilot PN offset which are not in use by other subscribers to its own handset. A controlling part determines different pilot PN offsets existing in an overlapped service region using pilot PN offsets stored in a storage region and energy values of the PN offsets to detect a pilot PN offset not in use, thus providing an optimal pilot channel signal to the cordless telephone system.

Claims

1. A device for detecting a pilot PN offset in a cordless telephone system, comprising:

pilot PN sequence generators each for generating a pilot PN sequence for tracking a synchronization of a pilot channel signal;

despreaders for despreading the pilot PN sequences provided from the pilot PN sequence generators and channel data signals detected within an overlapped service radius;

an accumulator for accumulating data streams of pilot channels provided from the despreaders for a certain period;

an energy value calculator for calculating an energy value of a signal from the accumulator;

a storage region for storing at least one different pilot PN offset detected within a set service region and threshold energy values; and

a controlling part for determining different pilot PN offsets existing in an overlapped service region using the pilot PN offsets stored in the storage region and energy values of the pilot PN offsets, and for detecting a pilot PN offset not in use.

2. A device as claimed in claim 1, wherein the storage region comprises at least one register and storage area, respectively.

3. A device as claimed in claim 1, which is operative in cases when a power is supplied thereto initially or resets the device completely.

4. The device of claim 1, wherein the controlling part is configured to construct a database of existing PN offsets and corresponding energy values.

5. The device of claim 1, wherein a detected PN offset and a corresponding energy value are stored in the storage region if the controlling part determines that the energy value of the detected PN offset exceeds a prescribed value.

6. The device of claim 5, wherein the controlling part constructs a database of all PN offsets and corresponding energy values that exceed the prescribed value.

7. The device of claim 6, wherein the prescribed value is a threshold energy value.

8. The device of claim 1, wherein the accumulator is coupled to receive a feedback signal directly from the controlling part.

9. The device of claim 1, wherein an accumulation time period of the accumulator is reduced if the energy value exceeds a threshold energy value.

10. A method for detecting a pilot PN offset in a cordless telephone system, comprising:

initializing a memory region;

measuring an energy value of a first pilot PN offset for at least one first pilot channel signal;

comparing the measured energy value of the first pilot PN offset for the at least one first pilot channel signal to a threshold energy value of a second pilot PN offset provided within an overlapped service radius in a prescribed sequence;

constructing a database using the first pilot PN offset for the at least one first pilot channel signal and the measured energy value of the first pilot PN offset when the measured energy value exceeds the threshold energy value of the second pilot PN offset; and

selecting the first pilot PN offset for one of the at least one first pilot channel signals which is not included in the database.

11. The method as claimed in claim 10, wherein the memory region is initialized by supplying a power initially or resetting the system.

12. The method as claimed in claim 10, wherein the memory region is not initialized when power is supplied to the system subsequent to an interruption of power for a prescribed period of time.

13. The method as claimed in claim 10, wherein constructing the database comprises:

sequentially storing resultants of the comparing step, and

constructing the database using the resultants of the comparing step.

14. The method as claimed in claim 13, wherein the resultants of the comparing step are used for directly constructing the database, and wherein constructing the database is performed at the same time as storing the resultants.

15. The method of claim 13, wherein the database is constructed after the resultants are stored.

16. The method as claimed in claim 10, wherein selecting the first pilot PN offset for one of the at least one first pilot channel signals comprises:

giving priorities to detected pilot PN offsets which are not included in the database according to states of other detected pilot PN offsets which are not included in the database; and

selecting a prioritized detected pilot PN offset of a best state in the priorities.

17. The method as claimed in claim 10, further comprising transmitting pilot channel signals continuously for despreading based on the selected pilot PN offset.

18. A cordless telephone system, comprising:

a handset; and

a base, wherein the base comprises,

a pilot PN sequence generator for generating a pilot PN sequence for tracking a synchronization of a pilot channel signal,

a despreader for despreading the pilot PN sequence provided from the pilot PN sequence generator and channel data signals detected within an overlapped service radius,

an accumulator for accumulating data streams of pilot channels provided from the despreader for a certain period,

an energy value calculator for calculating an energy value of a signal from the accumulator, and

a controlling part for determining a plurality of pilot PN offsets existing in an overlapped service region and corresponding energy values of the pilot PN offsets, and detecting a pilot PN offset not in use by comparison of the corresponding energy values to a threshold value.

19. The system of claim 18, wherein the threshold value is one of a measured value for each corresponding energy value of the pilot PN offsets and a prescribed value.

20. The system of claim 18, wherein the controlling part provides an optimal pilot channel signal when more than one of the plurality of pilot PN offset not in use are detected.

21. A method for operating a cordless telephone system, comprising:

obtaining a plurality of pilot PN offsets within an overlapped service radius;

comparing a measured enery value of each of the plurality of pilot PN offsets to a threshold energy value of the pilot PN offsets in a predetermined sequence;

constructing a database using a present pilot PN offset and an energy value of the present pilot PN offset when the measured energy value exceeds the threshold energy vaule of the present pilot PN offset; and

selecting one of the pilot PN offsets which is not included in the database.

22. The method of claim 21, wherein the cordless telephone system comprises a handset, and wherein the handset is configured to establish a comunication link