Nec Corporation

Mitsubishi Heavy Industries Limited

Ichiro Tsujimoto

Takashi Hirano

Akihisa Ushirokawa

Shingo Nishikata

Yoshihiro Sera

Yoshiyuki Fujimoto

A wireless communication system is provided. The wireless communication system includes a first wireless communication device; and a second wireless communication device, the first wireless communication device including a time-division multiplexing unit for time-division multiplexing a first modulated signal and a second modulated signal, and a transmission unit for transmitting a time-division multiplexed signal, the second wireless communication device including a time-division demultiplexing unit for time-division demultiplexing the time-division multiplexed signal into a first demodulated signal and a second demodulated signal, a first adaptive filter for the first demodulated signal, a second adaptive filter for the second demodulated signal, an adaptive control unit for performing an adaptive control on the first adaptive filter and outputting an output of the adaptive control to the second adaptive filter, a first demodulation unit for demodulating an output of the first adaptive filter, a second demodulation unit for demodulating an output of the second adaptive filter.

Wireless communication system, wireless communication device, and wireless communication method

An angle diversity receiving device performs angle diversity reception by configuring branches of angle diversity in accordance with received signals of an array antenna, the angle diversity receiving device being provided with:

Angle diversity receiving device and angle diversity receiving method

The present invention provides a radio communication apparatus that does not need installation of multiple radio devices in a communication node and requires only a single radio device to construct a data link of any of line-of-sight communication, over-the-horizon communication and aerial-vehicle communication. A radio communication apparatus includes a line-of-sight communication processing part that controls a beam from a phased array antenna to establish a line-of-sight communication, which is used when there is no obstacle in a radio transmission channel, an over-the-horizon communication processing part that controls the beam from the phased array antenna to establish an over-the-horizon communication, which is used when there is an obstacle in the radio transmission channel, and an aerial-vehicle communication processing part that controls the beam from the phased array antenna to establish an aerial-vehicle communication, which is used for communication with a communication node on a flying object, and the phased array antenna switches among the line-of-sight communication, the over-the-horizon communication and the aerial-vehicle communication.

Radio communication apparatus, radio network system, and data link construction method used for the same

A transmission side device combines two independent transmission signals (S , S ) together to produce two combined signals, i.e., a sum signal (S &plus;S ) and a difference signal (S &minus;S ), and transmits the produced signals over two radio wave propagation paths, respectively. After the sum signal and the difference signal are received by the reception side device, the sum signal and the difference signal, as received, are subjected to an AGC control operation and a complex-level multiplication operation with a weighting coefficient based on correlation control, and then separated into two, restored, independent signals.

Method and device for diversity transmission/reception

A spread spectrum diversity transmitter/receiver, in which a bit error rate is improved even at a severe multi path fading channel, is provided. At a transmitting section, a multi dimensional transmitting signal by code division is used not only for diversity itself but also for a convolutional encoding among diversity branches by a convolutional encoder. With this, an error correction function can be installed. At a receiving section, a Viterbi decoding is performed before a majority judgment is performed, a bit error at the front stage of a majority judging circuit is suppressed and the likelihood of the majority judgment is increased and consequently the bit error rate is largely improved.

Spread spectrum diversity transmitter/receiver

A spread-spectrum transceiver using a combination of time diversity and error-correction is disclosed. An error-correcting encoder encodes N-branch time-diversity signals to produce M-branch transmission signals consisting of N-branch information-bit signals and (M-N)-branch check-bit signals. The M-branch transmission signals are transmitted according to spread-spectrum system. At a receiving side, an error-correcting decoder decodes the M-branch received signals to produce N-branch time-diversity signals. After canceling the delay differences between the N-branch time-diversity signals, a received information signal is determined from the N received information signal according to majority logic.

Spread spectrum diversity transceiver

In a time diversity radio communications system, quadrature-modulated spread spectrum signals of different mutual time delay are combined into a code division multiplex signal and up-converted to a radio-frequency signal and transmitted. At a receive site, the signal is received by an antenna and down-converted to recover the code division multiplex signal. Quadrature-modulated component signals contained in the recovered code division multiplex signal are converted to baseband signals which are then time-aligned with each other. The time-aligned baseband signals are multiplied respectively by complex weighting factors and are combined together to produce an input signal for an adaptive equalizer. This input signal is also applied to an AGC amplifier where it is amplified and applied to correlation detectors where correlations between the amplified signal and the baseband signals are detected and the complex weighting factors are derived respectively from the correlations. In a modified embodiment, the quadrature-modulated component signals are fed into an adaptive RAKE matched filter where the output of the AGC amplifier is used for detecting the correlations.

Spread spectrum time diversity communications system

In first radio station and a second radio station constituting a radio transmission system using spatial duplex diversity, interference signals are cancelled by a power inversion adaptive array (PIAA). One branch of the transmission side is multiplied by a complex coefficient multiplier so that the desired received signal has the optimum vector value after a combination of two branches and PIAA processing. An envelope detector detects the received signal level with an envelope detector at the receiving side, feeds back the received signal level information to the transmission side through the transmission baseband circuit, extracts the information with the receiving baseband circuit at the transmission side, and inputs the information into a constant modulus algorithm control circuit. The constant envelope algorithm control circuit sequentially controls the complex coefficient multiplier so that the multiplier has an optimum value.

Method and apparatus for interference cancellation

At a transmitter side, signals are provided with a delay difference with a plurality of branches, coded multiplexed by spectrum spreaders and a combination unit, and transmitted by a single antenna. At a receiver side, the signals are received by a single antenna, and diversity branches are extracted and separated by first and second spectrum de-spreaders. They are subject to linear combination so that the mean square of the decision error signals is minimized. The output passes through an adaptive matched filter and an adaptive equalizer so as to provide an output from which interference waves are eliminated. Thus, interference is eliminated and diversity gain for a signal is ensured, while reducing the scale and cost of a system without using a plurality of antennae.

Method and apparatus for cancelling interference jamming in digital

A time diversity transmission-reception system has, on transmit side, at least one delay of a predetermined delay for providing at least a pair of delayed and undelayed data symbol sequences, at least a pair of modulators for modulating the data symbol sequences into modulated intermediate frequency signals, and at least a pair of spread spectrum signal generators employing mutually different pseudo-random code sequences for code division multiplexing. On receive side, the received signals are subjected to code division demultiplexing, demodulation, and delaying to restore at least a pair of timed demodulated signals. These signals are then subjected to adaptive matched filtering, whose outputs are combined and applied to adaptive equalization to provide diversity reception signal. The present system provides a plurality of diversity branches without employing a plurality of frequencies, planes of polarization of a carrier wave or receiving antennas. Also, principal part of the system of the present invention can be readily integrated into LSI's, contributing to the reduction of manufacturing cost.

Time diversity transmission-reception system

In a diversity communication system, groups of receive units are provided corresponding respectively to arrays of antennas to process incoming signals which are propagated over different paths from a transmitter. In order to orient the directivity patterns of the antenna arrays toward the transmitter, multiple diversity branches are provided corresponding respectively to the groups of receive units. Each diversity branch includes multiple complex multipliers for respectively multiplying the processed incoming signals from the corresponding receive units by weight coefficients. Delays are then introduced respectively to the processed incoming signals so that the delayed signals are time-coincident with a decision signal, and the weight coefficients of the complex multipliers are derived from correlations between the delayed signals and the decision signal. The outputs of the complex multipliers of each diversity branch are combined together to produce a sum signal, and the delay-dispersed components of the sum signal are converged and maximal-ratio combined in an adaptive matched filter according to the decision signals of the diversity branches. A diversity combiner combines the output signals of the diversity branches to produce a space-domain diversity-combined signal, which is then adaptively equalized by a decision feedback equalizer to produce the decision signal.

Diversity communication system with adaptably oriented multiple beam

In a decision feedback equalizer, symbols from an array of antennas are fed to a first filter where they are respectively multiplied with first weight coefficients and supplied to a combiner where they are combined with second symbols to produce a combined symbol. A decision circuit makes a decision on the combined symbol and produces a decision symbol. Decision symbols successively generated by the decision circuit are fed to a second filter where they are respectively multiplied with second weight coefficients and supplied to the combiner as the second symbols. A difference between the decision symbol and the combined symbol is detected to produce a decision error. Each of the first weight coefficients is updated according to the decision error and the symbol from each of the antenna systems and each of the second weight coefficients is updated according to the decision error and each of the decision symbols successively supplied from the decision circuit so that the mean square value of the decision error is reduced to a minimum.

Decision feedback equalizer with adaptive filter array operating as

In a decision feedback equalizer, transmitted signals are received by an array of antennas and baseband symbols are recovered. A forward filter provides weighting of the recovered baseband symbols with first coefficients so that precursor multipath components of a transmitted symbol are canceled and combines the weighted symbols. A set of first delay elements provide respective delays to one of the baseband symbols to produce a short- and a long-delayed baseband symbol. A set of correlators is provided for detecting correlations between the baseband symbol and the short- and long-delayed baseband symbols. A set of second delay elements provide respective delays to a decision symbol to produce a short- and a long-delayed decision symbol. A selector is responsive to a correlation detected by one of the correlators for selecting one of the short- and long-delayed decision symbols. A feedback filter shifts the selected decision symbol along a tapped-delay line to produce successively shifted decision symbols, multiplies them with second coefficients and combines the multiplied decision symbols to produce an output signal that cancels postcursor multipath components of the transmitted symbol. The output signals of the forward and feedback filters are combined to produce a pre-decision symbol which is used by a decision circuit to produce a decision output for coupling to the second delay elements as the aforesaid decision symbol.

Decision feedback equalizer for canceling short-and long-multipath

After coding transmission data by means of an error-correction coder, the data are divided into N branches, pass through a plurality of delay elements, undergo interleaving in an interleave circuit, primary modulation in a modulator, undergo spread-spectrum processing in a spread-spectrum circuit, and are coded/multiplexed in a synthesizer, and finally transmitted. The signals transmitted by the transmitter are divided into N branches by a branch circuit, undergo inverse spread-spectrum processing in inverse spread-spectrum circuits, undergo demodulation in a demodulator corresponding to the primary modulation on the transmission side, undergo de-interleaving at a de-interleave circuit, and after delay coordination at delay elements, undergo majority-discrimination at a majority-discrimination circuit, and finally are error corrected in an error-correction decoding circuit.

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Tokyo, Japan

Ichiro Tsujimoto