Wireless transmit/receive unit (WTRU) for carrier offset recovery

• US 8,254,431 B2
• Filed: 04/13/2011
• Issued: 08/28/2012
• Est. Priority Date: 05/14/1998
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Ozluturk, Fatih M, Mesecher, David K, Jacques, Alexander M
• Primary Examiner(s): Tran, Khai
• Application Number:
  US13/086,091
• Publication Number:
  US 20110188546A1
• Time in Patent Office: 503 Days
• Field of Search: 375/148, 375/130, 375/316, 375/152, 375/376, 375/342, 375/150, 370/342, 370/330, 370/335, 370/230, 370/411, 370/320
• US Class Current: 375/148
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/70755 Setting of lock conditions, e.g. threshold
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04L 2027/0067 Phase error detectors
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless transmit/receive unit (WTRU) for carrier offset recovery. An adaptive matched filter produces a filtered signal. A rake receiver provides relative path values of multipath components. A mixer generates channel impulse response estimates. A channel despreader despreads the filtered signal using the pseudo-noise signal generated to produce a despread channel signal of the selected channel. A pilot channel despreader despreads the filtered signal using a pseudo-noise signal generator to produce a despread pilot signal of the pilot channel. A hard decision processor determines a symbol value of the despread channel signal. A complex conjugate processor generates a complex conjugate of the symbol value as a correction signal. A phase-locked loop produces a phase correction signal to recover carrier offset.

Claims

1. A wireless transmit/receive unit (WTRU) for carrier-offset recovery during reception of a communication signal over an air interface using a reduced pilot signal, the WTRU comprising:

a receiver for receiving at least one of a plurality of digital spread spectrum channels in a wireless communication, the receiver comprising;

a hard decision processor in association with a complex conjugate processor configured to receive at least one despread channel signal of a selected channel and to produce a phase correction signal;

a multiple input phase-locked loop (PLL) configured to utilize a plurality of pseudo pilot signals for producing a carrier phase correction signal used for performing the carrier offset correction at a chip level or at a symbol level;

a mixer configured to mix the phase correction signal with a filter weighting signal to remove a relative phase error from the filter weighting signal and to produce a weighting signal; and

an adaptive matched filter configured to receive the communication signal and to produce a filtered signal by using the weighting signal produced from the phase correction signal.

2. The WTRU of claim 1 further comprising:

a rake receiver configured to receive the communication signal and a pseudo-noise signal generated for a selected channel and to produce the filter weighting signal in conjunction with a channel estimator using the phase correction signal;

at least one channel despreader coupled to the adaptive matched filter output configured to despread the filtered signal using the pseudo-noise signal generated for the selected channel to produce the at least one despread channel signal of the selected channel; and

a pilot channel despreader coupled to the adaptive matched filter output configured to despread the filtered signal using the pseudo-noise signal generated for the pilot channel to produce a despread pilot signal.

3. The WTRU of claim 2 wherein the number of channel despreaders coupled to the adaptive matched filter output is three.

4. The WTRU of claim 1 wherein the at least one despread channel signal is a complex, bi-phase modulated signal comprised of symbols including in-phase and quadrature components representing data, the hard decision processor compares each despread channel signal symbol to one of four possible quadrature constellation points and assigns each of the symbols to a nearest constellation point, and the complex conjugate processor derotates each of the symbols by determining a complex conjugate of each of the assigned points to produce the phase correction signal.

5. The WTRU of claim 1 wherein the phase-locked loop further comprises a plurality of inputs corresponding with the at least one channel despreader.

6. A method for a wireless transmit/receive unit (WTRU) for carrier-offset recovery during reception of a communication signal over an air interface using a reduced pilot signal, the method comprising:

receiving at least one of a plurality of digital spread spectrum channels in a wireless communication;

receiving, by a hard decision processor in association with a complex conjugate processor, at least one despread channel signal of a selected channel and to produce a phase correction signal;

utilizing, by a multiple input phase-locked loop (PLL), a plurality of pseudo pilot signals for producing a carrier phase correction signal used for performing the carrier offset correction at a chip level or at a symbol level;

mixing, by a mixer, the phase correction signal with a filter weighting signal to remove a relative phase error from the filter weighting signal and to produce a weighting signal; and

receiving, by an adaptive matched filter, the communication signal and producing a filtered signal by using the weighting signal produced from the phase correction signal.

7. The method of claim 6 further comprising:

receiving, by a rake receiver, the communication signal and a pseudo-noise signal generated for a selected channel and producing the filter weighting signal in conjunction with a channel estimator using the phase correction signal;

despreading, by at least one channel despreader coupled to the adaptive matched filter output, the filtered signal using the pseudo-noise signal generated for the selected channel to produce the at least one despread channel signal of the selected channel; and

despreading, by a pilot channel despreader coupled to the adaptive matched filter output, the filtered signal using the pseudo-noise signal generated for the pilot channel to produce a despread pilot signal.

8. The method of claim 7 wherein the number of channel despreaders coupled to the adaptive matched filter output is three.

9. The method of claim 6 wherein the at least one despread channel signal is a complex, bi-phase modulated signal comprised of symbols including in-phase and quadrature components representing data, the hard decision processor compares each despread channel signal symbol to one of four possible quadrature constellation points and assigns each of the symbols to a nearest constellation point, and the complex conjugate processor derotates each of the symbols by determining a complex conjugate of each of the assigned points to produce the phase correction signal.

10. The method of claim 6 wherein the phase-locked loop further comprises a plurality of inputs corresponding with the at least one channel despreader.