Automatic power control system for a code division multiple access (CDMA) communications system

• US 6,873,645 B2
• Filed: 04/12/2001
• Issued: 03/29/2005
• Est. Priority Date: 06/30/1995
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Ozluturk, Fatih, Kowalski, John, Lomp, Gary
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Ha, Dac V.
• Application Number:
  US09/833,285
• Publication Number:
  US 20010015998A1
• Time in Patent Office: 1,447 Days
• Field of Search: 375/130, 375/142, 375/144, 375/148, 375/150, 375/340, 375/343, 370/331, 370/332, 370/320, 370/335, 370/342, 370/441, 370/479, 455/13.4, 455/33.2, 455/38.3, 455/63, 455/67.1, 455/67.3
• US Class Current: 375/142
• 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 receiver receives signals and noise over a frequency spectrum of a desired received signal. The desired received signal is spread using code division multiple access. The received signals and noise are demodulated to produce a demodulated signal. The demodulated signal is despread using a code uncorrelated with a code associated with the desired received signal. A power level of the despread demodulated signal is measured as an estimate of the noise level of the frequency spectrum.

Claims

1. A method for estimating at a receiver a noise level in a frequency spectrum of a desired received signal, the desired received signal spread using code division multiple access, the estimated noise level for use in power control of a transmitter sending the received signal, the method comprising:

receiving signals and noise over the frequency spectrum at the receiver;

demodulating the received signals and noise to produce a demodulated signal;

despreading the demodulated signal using a code uncorrelated with a code associated with the desired received signal; and

measuring a power level of the despread demodulated signal as the estimated noise level of the frequency spectrum.

2. The method of claim 1 wherein the despreading is performed by an AUX despreader different than a despreader used to despread the desired received signal.

3. The method of claim 1 wherein prior to the despreading, a gain of the received signals and noise is adjusted using a variable gain amplifier.

4. The method of claim 3 wherein the received signals and noise are despread using the desired received signal code and a power level of the despread desired signal is measured as a power level of the received desired signal for use in power control of the transmitter.

5. A subscriber unit for use in a spread spectrum communication system using code division multiple access, a base station transmits a desired received signal over a frequency spectrum to the subscriber unit, the subscriber unit comprising:

a despreader having an input configured to receive demodulated received signals and noise over the frequency spectrum and despreading the received demodulated signals and noise using a code uncorrelated with a code associated with the desired received signal; and

a measure power device for measuring a power level of the despread signal as an estimate of a noise level with respect to the desired received signal.

6. The subscriber unit of claim 5 wherein the despreader is a AUX despreader which is different than a despreader of the desired received signal.

7. The subscriber unit of claim 5 further comprising a variable gain amplifier to adjust a gain of the received signals and noise prior to input to the despreader.

8. The subscriber unit of claim 7 further comprising:

a desired signal despreader for despreading the received demodulated signals and noise using the desired received signal code; and

the measure power device for measuring a power level of a despread result of the desired signal despreader.

9. A base radio carrier station (RCS) for use in a spread spectrum communication system using code division multiple access, a subscriber unit transmits a desired received signal over a frequency spectrum to the subscriber unit, the subscriber unit comprising:

a despreader having an input configured to receive demodulated received signals and noise over the frequency spectrum and despreading the received demodulated signals and noise using a code uncorrelated with a code associated with the desired received signal; and

a measure power device for measuring a power level of the despread signal as an estimate of a noise level with respect to the desired received signal.

10. The RCS of claim 9 wherein the despreader is a AUX despreader which is different than a despreader of the desired received signal.

11. The RCS of claim 9 further comprising a variable gain amplifier to adjust a gain of the received signals and noise prior to input to the despreader.

12. The RCS of claim 11 further comprising:

a desired signal despreader for despreading the received demodulated signals and noise using the desired received signal code; and

the measure power device for measuring a power level of a despread result of the desired signal despreader.