Commonwealth Scientific and Industrial Research Organisation

Motorola Corporation

Agere Systems Inc.

Xiaojing Huang

Yingjie Jay Guo

Jian Zhang

Darryn Lowe

Yunxin Li

Valeriy Dyadyuk

Mark Hedley

David Eric Humphrey

Joseph Abraham Pathikulangara

John David Bunton

Boyd Mcgregor Murray

A communication system including a transmitter and a receiver is disclosed. The transmitter transmits frames, at least two consecutive frames containing different training sequences. The receiver receives data communicated from the transmitter over a channel. The receiver combines and jointly processes the at least two consecutive frames transmitted by the transmitter to estimate a channel state of the channel.

Linear equalization for use in low latency high speed communication systems

Disclosed is a wireless transmitter comprising: a module configured to modulate input data bits into data symbols according to a predetermined modulation scheme, and group the data symbols into one or more precoding blocks; at least one symbol insertion module, each configured to insert one or more cancellation symbols into a corresponding precoding block; at least one precoding module, each configured to precode a corresponding precoding block; a subcarrier insertion module configured to concatenate the one or more precoded blocks and to insert at least one cancellation subcarrier into the concatenated precoded blocks to form a precoded OFDM symbol; a module configured to process the precoded OFDM symbol so as to reduce the out-of-band power emitted by the transmitter in transmitting the precoded OFDM symbol, wherein the processing uses the inserted cancellation symbols and cancellation subcarriers; and a module configured to transmit the processed precoded OFDM symbol over a wireless communication channel.

OFDM communications

Disclosed is a transmitter for a communication system. The transmitter comprises a sidelobe suppression module configured to apply a suppression matrix to an input vector comprising symbols to be transmitted by the transmitter; a modulation module configured to modulate the precoded vector to a time-domain symbol using a plurality of subcarriers, each symbol in the precoded vector having a corresponding subcarrier; and a digital-to-analog conversion module configured to convert the time-domain symbol to an analog waveform for transmission. The suppression matrix is constructed such that emissions at one or more predetermined suppression distances lying outside a frequency band defined by the subcarriers are set to zero according to a predetermined emission model.

Reducing out-of-band emission

Disclosed is an apparatus for estimating the location of a remote node. The apparatus comprises an antenna array comprising a plurality of elements in a fixed spatial arrangement, at least one element being a transmitting element configured to transmit a first wireless signal to the remote node, and at least two elements being receiving elements configured to receive a second wireless signal transmitted by the remote node in response to the first wireless signal. The apparatus further comprises a signal processing unit connected to the antenna array, the signal processing unit being configured to: estimate a plurality of round trip distances using the wireless signals, each round trip distance being from a transmitting element to the remote node and back to a receiving element; and estimate the location of the remote node using the round trip distance estimates.

Wireless localisation system

A transmission signal pre-processing method and apparatus for out-of-band emission cancellation are disclosed. For each of N subchannels in a band weighting each of N subchannel symbols by a calculated value in the range from 0 to 1 is performed. Precoding said N weighted symbols, organised as an N&#xd7;1 matrix, by multiplication by a unitary matrix is then performed.

Out-of-band emission cancellation

Disclosed is a communication modulator with sample rate conversion. The modulator comprises a symbol mapping module configured to map an input bitstream to a symbol sequence; a pre-distortion module configured to multiply the symbol sequence by a discrete frequency response to produce a pre-distorted symbol sequence; a modulation module configured to modulate the pre-distorted symbol sequence to a time-domain baseband sample sequence; a sample rate conversion module configured to convert the sample rate of the baseband sample sequence to a different sample rate to produce a sample-rate-converted baseband sample sequence; and an up-conversion module configured to up-convert the sample-rate-converted baseband sample sequence to an intermediate frequency signal. The discrete frequency response by which the pre-distortion module multiplies the symbol sequence is configured to compensate for passband droop introduced to the sample-rate-converted baseband sample sequence by the sample rate conversion module.

Arbitrary sample rate conversion for communication systems

Disclosed is a wireless communication signal peak-to-average power ratio reduction, method. The method comprises calculating a peak envelope from an envelope of an input signal using a clipping threshold; smoothing the peak envelope using a window function; mapping the smoothed peak envelope to an attenuation function using the clipping threshold; and applying the attenuation function to the input signal.

Peak-to average power ratio reduction for wireless communication systems

Disclosed is a hybrid antenna array () comprising a plurality of digital branches (), each digital branch including an analogue beamforming sub-array (e.g.-), each sub-array having a plurality of antenna elements (), a phase shifter () adapted to apply a phase shift to the signal from each antenna element, and a combiner (e.g.-) adapted to combine the phase-shifted signals. Each digital branch also includes a signal chain (e.g.-) adapted to convert the output of the sub-array to baseband. The hybrid antenna array also comprises a digital processing module (), including: an angle of arrival estimation sub-module () adapted to estimate an angle of arrival of a signal at the antenna elements; a phase control sub-module () adapted to control the phase shift applied by each phase shifter depending on the estimated angle of arrival; and a digital beamformer () adapted to combine the baseband signals from the digital branches using a weight vector to form an output signal ().

Hybrid adaptive antenna array

Disclosed is a method of processing a series of data bits for transmission on a transmit link, the method comprising mapping the series of data bits to a series of data symbols; demultiplexing the series of data symbols to a plurality of substreams of symbols; modulating each substream of symbols to a corresponding series of OFDM symbols; and space precoding the plurality of series of OFDM symbols to form one or more series of space precoded OFDM symbols, wherein the demultiplexing is dependent on channel state information for the transmit link.

Multiple-input multiple-output OFDM systems

In one embodiment, a transmitter converts digital input data into combined-OFDM signals and a receiver recovers data from the transmitted combined-OFDM signals. For transmission, digital data is mapped into data symbols using a commonly known modulation technique, such as QAM or DQPSK. The data symbols are subsequently divided into two or more groups according to a specified grouping pattern. Each group of data symbols is then converted into a separate OFDM subsymbol using IFFT processing. The OFDM subsymbols are then combined according to a specified combining pattern to create a combined-OFDM symbol. Combined-OFDM symbols are then prepared for transmission by affixing cyclic prefixes, converting the symbols to analog format, and performing spectral shaping of the analog signal. Upsampling may be employed to increase the signal bandwidth. In alternative embodiments, OFDM subsymbols may be combined using interleaving to create an interleaved-OFDM symbol.

Orthogonal frequency division multiplexing using subsymbol processing

In one embodiment, a demapper uses two hybrid-QPSK constellations to demap pairs of equalized data symbols recovered from 16-QAM, DCM OFDM symbols, wherein the equalized data symbols in a pair correspond to the same four-bit group. A first hybrid-QPSK constellation is generated by combining the real components of both 16-QAM mapping constellations onto one coordinate plane. The demapper generates a first set of two decision variables by combining the real components of each equalized data symbol in a pair to correspond to the first hybrid-QPSK coordinate plane. A log-likelihood ratio is then calculated for both decision variables in the set to determine likelihood estimates for the first and second bits of the four-bit group. This process is repeated for the imaginary components of each corresponding pair of equalized data symbols to generate likelihood estimates for the third and fourth bits of the four-bit group.

Demodulation of 16-QAM, DCM data symbols using two hybrid-QPSK constellations

A method and system for interactive channel equalization uses channel status information included in data packets. The system includes a first station adapted to transmit a first data packet including a channel status information segment over a radio communication channel as a first signal. A second station in the system includes a static pre-equalizer and an adaptive equalizer. The second station is adapted to receive the first signal and adaptively equalize the first signal using the adaptive equalizer and the channel status information to create a post hoc status estimate of the channel. The second station is further adapted to transmit a second data packet over the channel as a second signal, where the second signal is pre-equalized by the pre-equalizer using the post hoc status estimate of the channel. The method and system thus enable parameters of the channel equalization to be adjusted in real-time in response to varying channel conditions.

Method and system for interactive channel equalization

A filter bank () and receiver including the filter bank () that is designed for processing a baseband signal of a received continuous phase modulated signal S(t) with an integer modulation index. The filter bank () has outputs for providing a plurality of decision variable values (d,d,d,d) each representing a likelihood value of a symbol, from a group of predefined symbols that are likely to be present in the continuous phase modulated signal S(t). The filter bankhas filter units () each having an impulse response determined by a complex main pulse containing a majority of signal energy of one of the predefined symbols that is likely to be in the continuous phase modulated signal S(t).

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North Ryde, Australia

Xiaojing Huang