Adaptive vector correlator using weighting signals for spread-spectrum communications

• US 6,456,608 B1
• Filed: 01/18/2001
• Issued: 09/24/2002
• Est. Priority Date: 06/30/1995
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Lomp, Gary R.
• Primary Examiner(s): Cangialosi, Salvatore
• Assistant Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/765,048
• Time in Patent Office: 614 Days
• Field of Search: 370/335, 370/465, 370/310, 370/318, 370/320, 370/328, 370/329, 370/342, 370/468, 370/208, 370/209, 375/150, 375/152, 375/140, 375/142, 375/143
• US Class Current: 370/335
• CPC Class Codes: G06F 13/374 using a self-select method with individual priority code comparator
• CPC Class Codes: H03H 17/0226 comprising look-up tables
• CPC Class Codes: H03H 17/06 Non-recursive filters
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/70753 Partial phase search
• CPC Class Codes: H04B 1/70754 Setting of search window, i.e. range of code offsets to be searched H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/70755 Setting of lock conditions, e.g. threshold
• CPC Class Codes: H04B 1/70758 Multimode search, i.e. using multiple search strategies
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/711 the interference being multi-path interference
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates
• CPC Class Codes: H04B 2201/70707 : Efficiency-related aspects
• CPC Class Codes: H04B 2201/7071 : with dynamic control of receiver resources
• CPC Class Codes: H04B 7/2628 : using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04B 7/2637 : for logical channel control
• CPC Class Codes: H04B 7/264 : for data rate control
• CPC Class Codes: H04J 13/00 : Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 13/004 : Orthogonal
• CPC Class Codes: H04J 13/0048 : Walsh
• CPC Class Codes: H04J 13/0077 : Multicode, e.g. multiple codes assigned to one user
• CPC Class Codes: H04J 13/10 : Code generation
• CPC Class Codes: H04J 13/107 : by concatenation
• CPC Class Codes: H04J 13/12 : Generation of orthogonal codes
• CPC Class Codes: H04J 13/16 : Code allocation
• CPC Class Codes: H04J 2013/0037 : Multilevel codes
• CPC Class Codes: H04L 1/0001 : Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/004 : by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0042 : Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape H04L1/0067 takes precedence
• CPC Class Codes: H04L 1/0047 : Decoding adapted to other signal detection operation in conjunction with sequence estimation or equalization H04L25/03286
• CPC Class Codes: H04L 1/0054 : Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0059 : Convolutional codes
• CPC Class Codes: H04L 2027/003 : at baseband only
• CPC Class Codes: H04L 2027/0053 : Closed loops
• CPC Class Codes: H04L 25/0212 : of impulse response
• CPC Class Codes: H04L 27/206 : using a pair of orthogonal carriers, e.g. quadrature carriers
• CPC Class Codes: H04L 27/2332 : using a non-coherent carrier
• CPC Class Codes: H04L 5/1446 : of transmission speed
• CPC Class Codes: H04N 1/00912 : Arrangements for controlling a still picture apparatus or components thereof not otherwise provided for
• CPC Class Codes: H04N 1/3333 : during transmission, input or output of the picture signal; within a single document or page
• CPC Class Codes: H04N 2201/3335 : Speed or rate
• CPC Class Codes: H04W 52/04 : TPC
• CPC Class Codes: H04W 52/08 : Closed loop power control
• CPC Class Codes: H04W 52/143 : Downlink power control
• CPC Class Codes: H04W 52/146 : Uplink power control
• CPC Class Codes: H04W 52/24 : using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/241 : taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/245 : taking into account received signal strength
• CPC Class Codes: H04W 52/247 : where the output power of a terminal is based on a path parameter sent by another terminal
• CPC Class Codes: H04W 52/26 : using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/262 : taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001
• CPC Class Codes: H04W 52/322 : Power control of broadcast channels
• CPC Class Codes: H04W 52/325 : Power control of control or pilot channels
• CPC Class Codes: H04W 52/343 : taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 : distributing total power among users or channels
• CPC Class Codes: H04W 52/36 : with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/367 : Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/44 : in connection with interruption of transmission
• CPC Class Codes: H04W 52/50 : at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 52/52 : using AGC [Automatic Gain Control] circuits or amplifiers
• CPC Class Codes: H04W 52/54 : Signalisation aspects of the TPC commands, e.g. frame structure
• CPC Class Codes: H04W 52/60 : using different transmission rates for TPC commands
• CPC Class Codes: Y02D 10/00 : Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A pilot adaptive vector correlator for estimating channel-impulse response and for obtaining a reference value of received multipath signals in a spread-spectrum system. A code generator generates a plurality of replicas of a pilot-spreading-code signal, with each replica of the pilot-spreading-code signal having a different phase from other replicas in a plurality of replicas of pilot-spreading-code signals. Each correlator in a plurality of correlators uses a replica of the pilot-spreading-code signal with a different phase from the other correlators in the plurality of correlators. The plurality of correlators correlates the spread-spectrum signal with the plurality of replicas of the pilot-spreading-code signals. The plurality of correlators generates a noise-power level when a pilot-spreading-code signal is not in phase with a replica of the pilot-spreading-code signal, and a pilot signal-power level plus noise-power level when a pilot-spreading-code signal is in phase with a replica of the pilot-spreading-code signal. Using the detected-pilot signal and output signals from the plurality of correlators, a derotation-phaser circuit generates a derotation-phaser signal. Using the derotation-phaser signal, a correction circuit corrects the despread, multipath signals for effects of carrier-phase rotation.

Claims

1. A pilot adaptive vector correlator for correcting phase rotation of a plurality of received-multipath signals of a spread-spectrum signal having a pilot-spreading-code signal, comprising:

pilot-despreading means for generating a plurality of replicas of the pilot-spreading-code signal, with each of the plurality of replicas of the pilot-spreading-code signal having a different phase, said pilot-despreading means for despreading, using the plurality of replicas of the pilot-spreading-code signal, the plurality of received-multipath signals of the spread-spectrum signal as a plurality of despread-multipath signals;

said pilot-despreading means thereby generating a noise-power level when each pilot-spreading-code signal embedded in each of the plurality of received-multipath signals of the spread-spectrum signal is not in phase with any of the plurality of replicas of the pilot-spreading-code signal;

said pilot-despreading means thereby generating one or more detected-pilot signals, when one or more pilot-spreading-code signals embedded in the received-multipath signals of the spread-spectrum signal is in phase with one or more of the plurality of replicas of the pilot-spreading-code signal, respectively;

a pilot adder for combining a plurality of weighted-despread-multipath signals, as a combined-pilot signal;

phase-locked means, coupled to said pilot adder, for phase locking to the combined-pilot signal and for generating, from the phase-locked combined-pilot signal, a derotation-phaser signal;

correction means, coupled between said pilot-despreading means, said phase-locked means and said pilot adder, for multiplying and filtering each of the plurality of despread-multipath signals by the derotation-phaser signal, thereby generating a plurality of weighting signals, respectively;

said correction means for multiplying the plurality of despread-multipath signals by the plurality of weighting signals, to generate the plurality of weighted-despread-multipath signals, respectively;

acquisition-decision means, coupled to said pilot-despreading means, responsive to the one or more detected-pilot signals from said pilot-despreading means, for determining whether the one or more detected-pilot signals are synchronized to one or more of the plurality of replicas of the pilot-spreading-code signal;

said acquisition-decision means, responsive to detecting no synchronization, for sending a control signal to said pilot-despreading means, for offsetting the phase of one or more of the plurality of replicas of the pilot-spreading-code signals; and

said acquisition-decision means, responsive to detecting synchronization, for maintaining synchronization between the plurality of received-multipath signals and the plurality of replicas of the pilot-spreading-code signal.

2. The adaptive vector correlator as set forth in claim 1, for correcting phase rotation of a plurality of received-message-multipath signals of a message-spread-spectrum signal having a message-spreading-code signal, comprising:

message-despreading means for generating a plurality of replicas of the message-spreading-code signal, with the plurality of replicas of the message-spreading-code signal synchronized to the plurality of replicas of the pilot-spreading code signal, with each of the plurality of replicas of the message-spreading-code signal having a different phase, said message-despreading means for despreading, using the plurality of replicas of the message-spreading-code signal, the plurality of received-message-multipath signals of the message-spread-spectrum signal as a plurality of despread-message-multipath signals;

said message-despreading means thereby generating one or more detected-message signals, when one or more message-spreading-code signals embedded in the received-message-multipath signals of the message-spread-spectrum signal is in phase with one or more of the plurality of replicas of the message-spreading-code signal, respectively;

message-correction means, coupled to said pilot-correction means, for multiplying the plurality of despread-message-multipath signals by the plurality of weighting signals, to generate a plurality of weighted-despread-message signals, respectively; and

a message adder for combining the plurality of weighted-despread-message signals as a combined-message.

3. The pilot adaptive vector correlator as set forth in claim 1 or 2, with said pilot despreading means including:

a code generator for generating the plurality of replicas of the pilot-spreading-code signal;

a plurality of correlators, coupled to said code generator, with each of the plurality of correlators using one of the plurality of replica of the pilot-spreading-code signal, said plurality of correlators for correlating the spread-spectrum signal with the plurality of replicas of the pilot-spreading-code signal;

said plurality of correlators thereby generating the noise-power level when each pilot-spreading-code signal embedded in each of the plurality of received-multipath signals of the spread-spectrum signal is not in phase with any of the plurality of replicas of the pilot-spreading-code signal; and

said plurality of correlators for generating one or more detected-pilot signals and the noise-power level, when one or more pilot-spreading-code signals embedded in the received-multipath signals of the spread-spectrum signal is in phase with one or more of the plurality of replicas of the pilot-spreading-code signal, respectively.

4. The adaptive vector correlator as set forth in claim 1 or 2, with said pilot despreading means including a plurality of correlators for correlating the spread-spectrum signal with a plurality of phases of the plurality of replicas of the pilot-spreading-code signal, respectively.

5. The adaptive vector correlator as set forth in claim 1 or 2, with said pilot adder including means for adding the plurality of weighted-despread-multipath signals as the combined-pilot signal.

6. The adaptive vector correlator as set forth in claim 3, with said pilot adder including means for adding the plurality of weighted-despread-multipath signals as the combined-pilot signal.

7. The adaptive vector correlator as set forth in claim 4, with said pilot adder including means for adding the plurality of weighted-despread-multipath signals as the combined-pilot signal.

8. The adaptive vector correlator as set forth in claim 2, with said message adder including means for adding the plurality of weighted-despread-message signals as the combined-message signal.

9. The adaptive vector correlator as set forth in claim 3, with said message adder including means for adding the plurality of weighted-despread-message signals as the combined-message signal.

10. The adaptive vector correlator as set forth in claim 4, with said message adder including means for adding the plurality of weighted-despread-message signals as the combined-message signal.

11. A pilot adaptive vector correlator for correcting phase rotation of a plurality of received multipath signals of a spread-spectrum signal having a pilot-spreading-code signal, comprising:

a pilot-code generator for generating a plurality of replicas of the pilot-spreading-code signal, with each of the plurality of replicas of the pilot-spreading-code signal having a different phase;

a plurality of pilot-correlators, coupled to said pilot-code generator, for despreading, using the plurality of replicas of the pilot-spreading-code signal, the plurality of received-multipath signals of the spread-spectrum signal as a plurality of despread-multipath signals;

said plurality of pilot-correlators thereby generating a noise-power level when each pilot-spreading-code signal embedded in each of the plurality of received-multipath signals of the spread-spectrum signal is not in phase with any of the plurality of replicas of the pilot-spreading-code signal;

said plurality of pilot-correlators thereby generating one or more detected-pilot signals, when one or more pilot-spreading-code signals embedded in the received-multipath signals of the spread-spectrum signal is in phase with one or more of the plurality of replicas of the pilot-spreading-code signal, respectively;

a pilot adder for combining a plurality of weighted-despread-multipath signals, as a combined-pilot signal;

a phase-locked-loop (PLL) circuit, coupled to said pilot adder, for phase locking to the combined-pilot signal and for generating, from the phase-locked combined-pilot signal, a derotation-phaser signal;

a correction circuit, coupled between said plurality of pilot-correlators, said PLL circuit and said pilot adder, for multiplying and filtering each of the plurality of despread-multipath signals by the derotation-phaser signal, to generate a plurality of weighting signals, respectively;

said correction circuit for multiplying the plurality of despread-multipath signals by the plurality of weighting signals, to generate the plurality of weighted-despread-multipath signals, respectively;

an acquisition-decision circuit, coupled to said plurality of pilot-correlators, responsive to the one or more detected-pilot signals from said plurality of pilot-correlators, for determining whether the one or more detected-pilot signals are synchronized to one or more of the plurality of replicas of the pilot-spreading-code signal;

said acquisition-decision circuit, responsive to detecting no synchronization, for sending a control signal to said plurality of pilot-correlators, for offsetting the phase of one or more of the plurality of replicas of the pilot-spreading-code signals; and

said acquisition-decision circuit, responsive to detecting synchronization, for maintaining synchronization between the plurality of received-multipath signals and the plurality of replicas of the pilot-spreading-code signal.

12. The adaptive vector correlator as set forth in claim 11, for correcting phase rotation of a plurality of received-message-multipath signals of a message-spread-spectrum signal having a message-spreading-code signal, comprising:

a message-code generator for generating a plurality of replicas of the message-spreading-code signal, with the plurality of replicas of the message-spreading-code signal synchronized to the plurality of replicas of the pilot-spreading code signal, with each of the plurality of replicas of the message-spreading-code signal having a different phase;

a plurality of message correlators, coupled to said message-code generator, for despreading, using the plurality of replicas of the message-spreading-code signal, the plurality of received-message-multipath signals of the message-spread-spectrum signal as a plurality of despread-message-multipath signals;

said plurality of message correlators thereby generating one or more detected-message signals, when one or more message-spreading-code signals embedded in the received-message-multipath signals of the message-spread-spectrum signal is in phase with one or more of the plurality of replicas of the message-spreading-code signal, respectively;

a message-correction circuit, coupled to said plurality of message correlators, for multiplying the plurality of despread-message-multipath signals by the plurality of weighting signals, to generate a plurality of weighted-despread-message signals, respectively; and

a message adder for combining the plurality of weighted-despread-message signals as a combined-message.

13. The adaptive vector correlator as set forth in claim 11 or 12, with said pilot adder including means for adding the plurality of weighted-despread-multipath signals as the combined-pilot signal.

14. The pilot adaptive vector correlator as set forth in claim 11 or 12, with said message adder including means for adding the plurality of weighted-despread-message signals as the combined-message signal.

15. A pilot adaptive vector correlation method for correcting phase rotation of a plurality of received multipath signals of a spread-spectrum signal having a pilot-spreading-code signal, comprising the steps of:

generating a plurality of replicas of the pilot-spreading-code signal, with each of the plurality of replicas of the pilot-spreading-code signal having a different phase;

despreading, using the plurality of replicas of the pilot-spreading-code signal, the plurality of received-multipath signals of the spread-spectrum signal as a plurality of despread-multipath signals;

generating a noise-power level when each pilot-spreading-code signal embedded in each of the plurality of received-multipath signals of the spread-spectrum signal is not in phase with any of the plurality of replicas of the pilot-spreading-code signal;

generating one or more detected-pilot signals, when one or more pilot-spreading-code signals embedded in the received-multipath signals of the spread-spectrum signal is in phase with one or more of the plurality of replicas of the pilot-spreading-code signal, respectively;

combining a plurality of weighted-despread-multipath signals, as a combined-pilot signal;

phase locking to the combined-pilot signal;

generating, from the phase-locked combined-pilot signal, a derotation-phaser signal;

multiplying and filtering each of the plurality of despread-multipath signals by the derotation-phaser signal, to generate a plurality of weighting signals, respectively;

multiplying the plurality of despread-multipath signals by the plurality of weighting signals, to generate the plurality of weighted-despread-multipath signals, respectively;

determining, from the one or more detected-pilot signals, whether the one or more detected-pilot signals are synchronized to one or more of the plurality of replicas of the pilot-spreading-code signal;

sending, in response to detecting no synchronization, a control signal for offsetting the phase of one or more of the plurality of replicas of the pilot-spreading-code signals; and

maintaining, in response to detecting synchronization, synchronization between the plurality of received-multipath signals and the plurality of replicas of the pilot-spreading-code signal.

16. The method as set forth in claim 15, for correcting phase rotation of a plurality of received-message-multipath signals of a message-spread-spectrum signal having a message-spreading-code signal, further comprising the steps of:

generating a plurality of replicas of the message-spreading-code signal, with the plurality of replicas of the message-spreading-code signal synchronized to the plurality of replicas of the pilot-spreading code signal, with each of the plurality of replicas of the plurality of replicas of the message-spreading-code signal having a different phase;

despreading, using the plurality of replicas of the message-spreading-code signal, the plurality of received-message-multipath signals of the message-spread-spectrum signal as a plurality of despread-message-multipath signals;

generating one or more detected-message signals, when one or more message-spreading-code signals embedded in the received-message-multipath signals of the message-spread-spectrum signal is in phase with one or more of the plurality of replicas of the message-spreading-code signal, respectively;

multiplying the plurality of despread-message-multipath signals by the plurality of weighting signals, to generate a plurality of weighted-despread-message signals, respectively; and

combining the plurality of weighted-despread-message signals as a combined-message.

17. The method as set forth in claim 15 or 16, with the step of combining the plurality of weighted-despread-multipath signals as a combined-pilot further including the step of adding the plurality of weighted-despread-multipath signals as a combined-pilot signal.

18. The method as set forth in claim 15 or 16, with the step of combining the plurality of weighted-despread-message signals as a combined-message further including the step of adding the plurality of weighted-despread-message signals as a combined-message.