Pre-phase error correction

• US 8,488,650 B2
• Filed: 04/09/2009
• Issued: 07/16/2013
• Est. Priority Date: 03/28/2000
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Kaewell, John D.
• Primary Examiner(s): Tran, Khai
• Application Number:
  US12/421,028
• Publication Number:
  US 20090196330A1
• Time in Patent Office: 1,559 Days
• Field of Search: 375/147, 375/141, 375/130, 375/296, 375/326, 375/377, 375/221, 375/285, 455/24, 455/69
• US Class Current: 375/147
• CPC Class Codes: H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 1/711 the interference being multi-path interference
• CPC Class Codes: H04B 2001/70724 featuring pilot assisted reception
• CPC Class Codes: H04B 2201/696 relating to Dowlink
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference
• CPC Class Codes: H04L 2027/0022 using the carrier of the associated receiver of a transceiver
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits

Abstract

A CDMA communication system includes a signal processor which encodes voice and nonvoice signals into data at various rates, e.g. data rates of 8 kbps, 16 kbps, 32 kbps, or 64 kbps as I and Q signals. The signal processor selects a specific data rate depending upon the type of signal, or in response to a set data rate. When the signal is received and demodulated, the baseband signal is at the chip level. Both the I and Q components of the signal are despread using the conjugate of the pn sequence used during spreading, returning the signal to the symbol level. Carrier offset correction is performed at the symbol level. A lower overall processing speed is therefore required.

Claims

1. A mobile user device comprising:

a receiver configured to receive a radio frequency signal;

wherein the receiver is further configured to despread a plurality of data signals and to despread a pilot signal from the radio frequency signal;

wherein a phase of each of the data signals was adjusted prior to transmission; and

wherein the mobile user device is configured to derive a correction signal, the correction signal including weights to adjust the phase of the data signals, and to send the correction signal to a base station so that the phase of the data signals are adjusted in response to the correction signal.

2. The mobile user device of claim 1 wherein the correction signal is derived from the pilot signal.

3. The mobile user device of claim 1 wherein the data signals only include data.

4. The mobile user device of claim 1 wherein each of the plurality of data signals is received over an in-phase and a quadrature carrier of the radio frequency signal.

5. The mobile user device of claim 1 wherein the pilot signal is a QPSK signal.

6. The mobile user device of claim 1 wherein each of the data signals is a QPSK signal.

7. A method comprising:

receiving a radio frequency signal by a mobile user device;

despreading a plurality of data signals and despreading a pilot signal from the radio frequency signal by the mobile user device;

wherein a phase of each of the data signals was adjusted prior to transmission; and

deriving a correction signal, the correction signal including weights to adjust the phase of the data signals, and sending the correction signal to a base station by the mobile user device so that the phase of the data signals are adjusted in response to the correction signal.

8. The method of claim 7 wherein the correction signal is derived from the pilot signal.

9. The method of claim 7 wherein the data signals only include data.

10. The method of claim 7 wherein each of the plurality of data signals is received over an in-phase and a quadrature carrier of the radio frequency signal.

11. The method of claim 7 wherein the pilot signal is a QPSK signal.

12. The method of claim 7 wherein each of the data signals is a QPSK signal.

13. A base station comprising:

a transmitter to adjust a phase of a plurality of spread data signals in response to a correction signal, the correction signal including weights to adjust the phase of the data signals;

wherein the correction signal was received from a mobile device;

wherein the transmitter is further configured to transmit the plurality of phase adjusted data signals to the mobile station and to transmit a spread pilot signal.

14. The base station of claim 13 wherein each of the plurality of data signals is transmitted over an in-phase and a quadrature carrier of a radio frequency signal.

15. The base station of claim 13 wherein the pilot signal is a QPSK signal.

16. The base station of claim 13 wherein each of the data signals is a QPSK signal.

17. The base station of claim 13 wherein the spread data signals only include data.