Nec Corporation

Ntt Docomo, Inc.

Shinya Muraoka

Yasushi Maruta

Satoshi Oura

A channel estimation circuit () of an individual CH path demodulation unit (A-L) performs a channel estimation from an individual CH. A channel estimation value correction circuit () of a shared CH path demodulation unit (A-L) then corrects a reception power fluctuation due to uplink transmission power control which is caused by the timing offset between the individual CH and the shared CH. The resultant data is used for the demodulation by a shared CH demodulation circuit ().

CDMA receiving apparatus and method

A CDMA base station is disclosed that prevents significant increase in the amount of interference within an entire cell even when there exist in the cell mobile stations that perform high-speed packet communication. The CDMA base station comprises a noise estimation circuit, a noise comparator and a TPC bit generating circuit. The noise comparator receives noise power Nestimated by the noise estimation circuit, compares the noise power Nwith a threshold Nfor interference supplied from packet communication circuitand outputs the result of comparison Nto the TPC bit generating circuit. The TPC bit generating circuit sets TPC=0, outputting TPC command TPCto direct a TPC multiplex circuit to reduce the transmission power, without using TPC command TPCfrom a SIR estimation circuit when the increase in the transmission power of a mobile station that is performing high-speed packet transmission within a fixed period of time has exceeded the threshold for the increase or when the amount of interference in the entire cell has exceeded the threshold for the amount of interference.

Uplink transmission power control in a CDMA base station

A control circuit () determines transmission power for a test signal in accordance with the number of call connections of a radio terminal call-connected to the apparatus during a loopback test. The determined transmission power (TSTP) is output to channel circuits (-) used for the transmission of a loopback test signal. The channel circuits (-) adjust the transmission power of the test signal on the basis of the transmission power (TSTP) from the control circuit ().

Radio base station apparatus and its loopback test method

A difference between DELAY values of paths is compared and when the difference is below a predetermined value, the paths are assumed to be the same and SIRs estimated for these paths are compared to each other. The SIRs are multiplied by corresponding weighting coefficients and are added in an SIR addition circuit. This eliminates erroneous recognition of one path as a plurality of paths, causing an enormous SIR after the addition and prevents deterioration of the line quality.

Transmission power control circuit using W-CDMA method

A DC-offset eliminating circuit changes a coefficient &#x3b1; for determining a DC-offset follow-up speed. The coefficient &#x3b1; is changed to a smaller value or 0 in a case where a signal showing a detection that a reception is ceased, is received from a signal-end detecting circuit, or in a case where a signal for partly turning off the circuits for the reduction of power consumption is received from a control circuit, if the received frame is not destined for the receiver itself. The circuit remains the coefficient &#x3b1; to a smaller value immediately after the reception is resumed. Additionally, the circuit returns the coefficient &#x3b1; to the normal value in response to the reception of a signal showing that an alignment signal is detected immediately after a preamble portion. The circuit then reduces the DC-offset follow-up speed as much as possible at the time when the preamble portion is received, thereby avoiding the DC-offset deviation caused by the preamble patterns.

DC-offset eliminating method and receiving circuit

To implement highly accurate SIR estimation and thereby perform stable transmission power control immediately after starting user communication. A common control circuit has an ISSI value of each sector stored therein. On starting the user communication, the common control circuit outputs to a communication channel circuit for starting the communication the ISSI value corresponding to a sector where the communication is started of the stored ISSI values. The communication channel circuit performs the SIR estimation of a received signal by using the ISSI value and also performs the user communication. The communication channel circuit stores the ISSI value on finishing the communication in the common control circuit in the case where the communication is finished.

Radio base station, mobile station, radio receiving apparatus, SIR estimation method, transmission power controlling method and program

Method and apparatus for controlling data transmission according to quality of communication line

A UW multiplexing circuit multiplexes a fixed pattern over the leading edge of each frame of transmit data. A spreading code generating circuit generates spreading codes TP1 at a timing synchronized with the frame. A spreading circuit spread-modulates data from the UW multiplexing circuit with the spreading codes TP1. A correlation detecting circuit has spread-modulated fixed patterns as multiplication coefficients, and detects correlations between spread-modulated fixed patterns in received data. A despreading code generating circuit supplies, if a fixed pattern is detected, the leading code of despreading codes RP1. A despreading circuit despread-modulates the receive data with the despreading codes RP1. As a result, the spread spectrum communication apparatus according to the invention is capable of setting the code length and the bandwidth expansion factor independent of each other, and thereby enhancing the performance to detect correlated values.

Spread spectrum communication method and spread spectrum communication apparatus

In a mobile radio communication apparatus, including a transmission circuit for intermittently transmitting first significant signals and a reception circuit for receiving second significant signals, a control circuit changes a strength of the first significant signals in accordance with a strength of the second significant signals only when the second significant signals are being received by the reception circuit.

Mobile radio communication apparatus capable of reducing power dissipation

In an echo canceler, a first adaptive filter circuit calculates first tap coefficients using a first convergence coefficient, and generates a first pseudo echo signal, and a first subtracter subtracts the first pseudo echo signal from a transmitting signal to generate a first error signal. A second adaptive filter circuit calculates second tap coefficients using a second convergence coefficient, and generates a second pseudo echo signal, and a second substrate subtracts the second pseudo echo signal from the transmitting signal to generate a second error signal. A control circuit selects one set of the first tap coefficients and the second tap coefficients in accordance with a received signal, the transmitting signal, and the first and second error signals. A third adaptive filter circuit generates a third pseudo echo signal in accordance with the set of tap coefficients selected by the control circuit and the received signal, and a third subtracter subtracts the third pseudo echo signal from the transmitting signal to generate a third error signal.

Echo canceler having plurality of adaptive filter circuits

A satellite communication apparatus is capable of accurately determining whether there is a received audio signal or not without being affected by ambient conditions, for thereby preventing the characteristics of an adaptive filter from being degraded. A demodulator demodulates a signal received by an antenna, generating synchronizing frame data and a synchronizing frame signal. At this time, the demodulator also generates a synchronization status signal indicating whether the synchronizing frame signal is being generated at a constant period or not. An echo canceler determines whether there is an audio signal or not on based on the synchronization status signal which has been generated by the demodulator and delayed for a given period of time by a delay circuit. Based on the determined result, the echo canceler estimates tap coefficients for generating a quasi-echo signal, and updates the quasi-echo signal.

Satellite communication apparatus

As for wireless communication lines between a master station and a plurality of remote stations, each remote station has a function F having an unitary variable which is known over all the stations and has two unique IDs, respectively. The master station is provided with a remote station ID memory circuit which outputs one ID of a remote station when the other ID of the remote station is input thereto, and a scrambler. carries out scrambling by using a fixed scramble vector VO during a setup sequence period and using a scramble vector VF set from a master station control circuit at the time of data transmission. A descrambler descrambles an input signal from the remote station by using the scramble vector VO during the setup sequence period and using a scramble vector VR set from the master station control circuit at the time of data transmission.

Scramble wireless communication system

In a reception circuit, a frame status signal indicating whether frame synchronization is established is output from a frame synchronizing circuit to a frame counter circuit. When the frame synchronization is established, a timing signal synchronized with a reception frame pulse is output from the frame counter circuit. When the frame synchronization is not established or out of synchronization, a built-in frame counter is operated in a flywheel mode to output a timing signal to synchronize a baseband circuit and an I/F buffer circuit, so that communication with an external circuit can be kept normal irrespective of presence or absence of frame synchronization.

Reception circuit for a baseband processing and operation

An echo canceller (30) cancels an echo signal produced on a transmission path (14) on the basis of a received signal received through a reception path (15). The echo canceller comprises an adaptive filter (31) for producing a pseudo-echo signal from the received signal in accordance with tap gains. A producing section (19, 20) produces an error signal representative of an error level between the echo signal and the pseudo-echo signal. A supplying section (21, 32) supplies the adaptive filter with selected tap gains stored in a memory section (18) when the error level is less than a predetermined threshold level. The adaptive filter renews the selected tap gains into renewal tap gains in accordance with the received signal and the error signal to store the renewal tap gains of the selected tap gains in the memory section.

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Tokyo, Japan

Shinya Muraoka