Apparatus and method for measuring noise power in a CDMA mobile communication system

• US 6,822,998 B1
• Filed: 09/18/2000
• Issued: 11/23/2004
• Est. Priority Date: 09/18/1999
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yoon, Soon-Young, Maeng, Seung-Joo, Yun, Yu-Suk
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/663,643
• Time in Patent Office: 1,527 Days
• Field of Search: 375/142, 375/147, 375/145, 375/150, 375/342, 375/349, 375/136, 375/50, 370/335, 370/331, 370/320, 370/342, 370/441
• US Class Current: 375/130
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters

Abstract

A noise power measuring system and method for a base station receiver are disclosed. In the system and method, a received signal is despread and the noise power of the despread received signal is estimated. An orthogonal code generator generates a noise power measurement orthogonal code, which is orthogonal to all the orthogonal codes presently being used by the mobile station. A correlator connected to the orthogonal code generator performs a correlation operation between the noise power measurement orthogonal code and the despread received signal. A noise power measurer connected to the correlator, measures the noise power from the output of the correlator.

Claims

1. A base station receiver in a CDMA (Code Division Multiple Access) mobile communication system, for measuring a signal-to-noise ratio (SNR) of a signal received at the base station over at least one of a plurality of channels in a mobile station transmitter, each of the plurality of the channels having a corresponding orthogonal code, said receiver comprising:

a despreader for despreading the received signal with a complex despreading sequence;

a noise power measurer for measuring noise power from the despread received signal provided from the despreader by removing signal power by using a noise power measurement orthogonal code which is orthogonal with at least one of the orthogonal codes of the plurality of the channels;

a signal power measurer for measuring signal power from the despread received signal provided from the despreader; and

an SNR measurer for measuring an SNR by receiving the noise power from the noise power measurer and the signal power from the signal power measurer.

2. The base station receiver as claimed in claim 1, wherein the noise power measurer comprises:

an orthogonal code generator for generating the noise power measurement orthogonal code;

a correlator connected to the orthogonal code generator, for performing correlation operation between the noise power measurement orthogonal code and the despread received signal from the despreader; and

a power measurer connected to the correlator, for measuring the noise power from an output of the correlator.

3. The base station receiver as claimed in claim 1, wherein the noise power measurement orthogonal code is ‘

1,1,1,1,−

1,−

1,−

1,−

1,−

1,−

1,−

1,−

1,1,1,1,1’

.

4. The base station receiver as claimed in claim 1, wherein the noise power measurement orthogonal code is ‘

1, 1,−

1,−

1’

.

5. The base station receiver as claimed in claim 1, wherein the noise power measurement orthogonal code is ‘

1,−

1’

.

6. The base station receiver as claimed in claim 1, wherein the noise power measurer removes the signal power from the despread received signal by multiplying the despread signal with the noise power measurement orthogonal code.

7. The base station receiver as claimed in claim 2, wherein the noise power measurer further comprises:

an orthogonal code selector for receiving a channel state signal indicating at least one of the corresponding orthogonal codes used for at least one of the plurality of the channels and selecting an appropriate orthogonal code to be the noise power measurement orthogonal code according to the channel state signal.

8. The base station receiver as claimed in claim 7, wherein the orthogonal code generator generates the selected orthogonal code as the noise power measurement orthogonal code.

9. The base station receiver as claimed in claim 1, further comprising a synchronization (sync) acquisition device for acquiring synchronization from the received signal and generating a sync acquisition signal for synchronizing the despreader and the orthogonal code generator with the received signal.

10. The base station receiver as claimed in claim 2, wherein the noise power measurer further comprises an averaging device for calculating an average value of the noise power from the power measurer, said average value being taken over a symbol unit, and for generating the calculated average noise power as a noise power measurement signal.

11. A noise power measuring apparatus of a receiver for despreading a signal received over at least one of a plurality of channels and estimating noise power from the despread received signal, in a CDMA mobile communication system having the receiver and a transmitter, the apparatus comprising:

an orthogonal code generator for generating one of orthogonal codes which are orthogonal with and different from an orthogonal code used for said at least one channel;

a correlator connected to the orthogonal code generator, for performing correlation operation between the orthogonal code generated by the orthogonal code generator and the despread received signal; and

a power measure connected to the correlator, for measuring noise power from an output of the correlator.

12. The noise power measuring apparatus as claimed in claim 11, wherein the orthogonal code generator generates an orthogonal code of ‘

1,1,1,1,−

1,−

1−

1,−

1,−

1,−

1,−

1,−

1,1,1,1,1’

.

13. The noise power measuring apparatus as claimed in claim 11, further comprising:

an orthogonal code selector for receiving a channel state signal indicating an orthogonal code used for said at least one channel, and selecting one of orthogonal codes which are orthogonal with and different from said orthogonal code of said at least one channel according to the channel state signal.

14. The noise power measuring apparatus as claimed in claim 12, further comprising a synchronization (sync) acquisition device for acquiring synchronization from the received signal and generating a sync acquisition signal for synchronizing the orthogonal code generator with the received signal.

15. The noise power measuring apparatus as claimed in claim 11, further comprising an averaging device for calculating an average value of the noise power from the power measurer, said average value being taken over a symbol unit, and for generating the calculated average noise power as a noise power measurement signal.

16. A method for measuring a signal-to-noise ratio (SNR) of a signal received at a base station over at least one of a plurality of channels in a mobile station transmitter for a CDMA mobile communication system, each of the plurality of the channels having a corresponding orthogonal code, the method comprising the steps of:

despreading the received signal with a complex despreading sequence;

measuring noise power from the despread received signal by removing signal power by using a noise power measurement orthogonal code which is orthogonal with at least one of the orthogonal codes of the plurality of the channels;

measuring signal power from the despread received signal; and

measuring an SNR based on the noise power and the signal power.

17. The method as claimed in claim 16, wherein the noise power measuring step comprises the steps of:

generating the noise power measurement orthogonal code;

performing correlation operation between the noise power measurement orthogonal code and the despread received signal; and

measuring the noise power from an output of the correlation operation.

18. The method as claimed in claim 16, wherein the noise power measurement orthogonal code is ‘

1,1,1,1,−

1,−

1,−

1,−

1,−

1 ,−

1,−

1,−

1,1,1,1,1’

.

19. The method as claimed in claim 16, wherein the noise power measurement orthogonal code is ‘

1,1,−

1,−

1’

.

20. The method as claimed in claim 16, wherein the noise power measurement orthogonal code is ‘

1,−

1 ’

.

21. The method as claimed in claim 16, wherein the signal power is removed by multiplying the despread received signal with the noise power measurement orthogonal code.

22. The method as claimed in claim 17, wherein the orthogonal code generation step comprises the steps of:

receiving a channel state signal indicating at least one of the corresponding orthogonal codes used for at least one of the plurality of the channels;

selecting an appropriate orthogonal code to be the noise power measurement orthogonal code according to the channel state signal; and

generating the selected orthogonal code.

23. The method as claimed in claim 16, further comprising the steps of:

acquiring synchronization from the received signal; and

generating a synchronization (sync) acquisition signal for synchronizing the despreading operation with the noise power measuring operation.

24. The method as claimed in claim 16, wherein the noise power measuring step further comprises the steps of:

calculating an average value of the measured noise power in a symbol unit; and

generating the calculated average noise power as a noise power measurement signal.

25. A method for measuring noise power of a received signal in a base station for a Code Division Multiple Access (CDMA) mobile communication system, said received signal being transmitted over at least one of a plurality of channels in the mobile communication system and each of the channels having a corresponding orthogonal code, the method comprising the steps of:

despreading the received signal with a complex despreading sequence;

generating a noise power measurement orthogonal code, said noise power measurement orthogonal signal being orthogonal to at least one of the orthogonal codes of the channels;

performing correlation operation between the generated noise power measurement orthogonal code and the despread received signal; and

measuring noise power from a resulting value of the correlation operation.

26. The method as claimed in claim 25, wherein the generated noise power measurement orthogonal code is ‘

1,1,1,1,−

1,−

1−

1,−

1,−

1,−

1,−

1,−

1,1,1,1,1’

.

27. The method as claimed in claim 25, wherein the noise power measurement orthogonal code generation step comprises the steps of:

receiving a channel state signal indicating at least one of the corresponding orthogonal codes used for said at least one of the channels;

selecting the noise power measurement orthogonal code from at least one orthogonal code which is orthogonal to the at least one of the orthogonal codes indicated in the channel state signal; and

generating the selected orthogonal code.

28. The method as claimed in claim 25, further comprising the steps of:

acquiring synchronization from the received signal; and

generating a synchronization (sync) acquisition signal for synchronizing the noise power measurement orthogonal code with the received signal.

29. The method as claimed in claim 25, further comprising the steps of:

calculating an average value of the noise power, said average being taken over a symbol unit; and

generating the calculated average noise power as a noise power measurement signal.