 Device for measuring the average value of pulse signals |
| OF THE PRESENT FIG. 5 illustrates an embodiment of the present invention, in which the parts ... |
|
| Audio scrambling system for scrambling and descrambling audio signals |
| Therefore, the first object of the present invention is to provide an audio scrambling system for ... |
|
| Radio communication systems |
| I claim: 1. A radio communication system comprising a base station which is arranged in ... |
|
| Multi-user acquisition procedure for multipoint-to-point synchronous CDMA systems |
| The foregoing and other problems are overcome and the objects of the invention are realized by ... |
|
| Method of addressing messages and communications system |
| The invention provides a wireless identification device configured to provide a signal to identify ... |
|
| Method of detecting reference symbols for a digital data receiver |
| A particular object of the present invention is to mitigate that drawback. More precisely, an ... |
|
| Method for adaptively filtering doppler signals using a complex time domain filter |
| The present invention relates to a time domain technique which implements an adaptive wall filter ... |
|
| Spatial diversity processing for underwater acoustic telemetry |
| OF PREFERRED EMBODIMENT(S) The spatial diversity system of the present invention provides a means ... |
|
| Developing a channel impulse response by using distortion |
| FIG. 1 shows a high-level block diagram of a DAB communications system 10 embodying the principles ... |
|
| Decision feedback filter device in the frequency domain |
| A more advantageous way to improve the correction of the intersymbol interference is to use an ... |
|
|
CDMA mobile communication system and method with improved phase correction features
| Details |
Inventors: Ohgoshi, Yasuo; Doi, Nobukazu; Yano, Takashi;
Assignee: Hitachi, Ltd. (Tokyo, JP)
Primary Examiner: Hsu; Alpus H.
Assistant Examiner:
Attorney, Agent or Firm: Antonelli, Terry, Stout & Kraus, LLP
A mobile station of a code division multiple access mobile communication system for transmission by carrying out quadrature multiplexing of a pilot signal and a data signal having I and Q components spread by spectrum from the base station to the mobile station, includes a despreading circuit for generating phase error signals (.DELTA.I, .DELTA.Q) by despreading the quadrature multiplexed reception signals (I', Q') by using despreading codes for pilot symbol, another spreading circuit for generating a data signal group by despreading the reception signals by using spreading codes for data symbol, accumulators for converting the transmission rate of the phase error signals and the data signal group into the symbol rate, an averaging circuit for generating phase correction signals from the phase error signals of the symbol rate, and a phase correction circuit for generating data signals (I, Q) with the phase shifts being removed therefrom, by correcting the data signal group by the phase correction signals. |
|
DETAILED DESCRIPTION It is an object of the present invention to provide a mobile station of a CDMA mobile communication system and a detection method used at the mobile station, capable of performing a phase correction process by using low speed clocks with lower power consumption requirements compared with conventional CDMA mobile communications systems.
In order to achieve the above object, at a mobile station of this invention, a phase error signal outputted from a pilot signal despreading circuit at a chip rate of a despreading code and a data signal outputted from a data signal despreading circuit at the chip rate of the despreading code are converted into signals having a symbol rate of transmission data, and the phase of the data signal is corrected by a correction signal generated by the phase error signal.
In this case, phase correction signals (COS.
phi.
, SIN.
phi.
) are obtained by serial-to-parallel converting phase error signals (.
DELTA.
cos.
phi.
, .
DELTA.
sin.
phi.
) converted to have a symbol rate by using relatively low speed shift registers operating at the symbol rate, and by averaging the phase error signals for a plurality of symbols by using adders.
In a conventional mobile station, after the phases of the reception signals are corrected, the reception signals are despread by using despreading codes for data symbol to extract the I and Q components of the reception data signals.
According to the present invention, after the I and Q components of the reception signals obtained by quadrature detection are despread by the data signal despreading circuit, the transmission rate of the data signal group outputted from the data signal despreading circuit is changed to the symbol rate, and the data signal group is inputted via a delay circuit to a phase correction circuit.
With the above structure of this invention, the process of averaging phase error signals, data signal delay process, and data signal phase correction process can be performed at the symbol rate.
Therefore, the circuit portions for these processes can be operated at low speed clocks and a power consumption can be reduced
|
|
Multiplexer-related 
