Kabushiki Kaisha Toshiba

Filippo Tosato

Magnus Stig Torsten Sandell

Amr Ismail

Yong Sun

Fengming Cao

Sedat Gormus

Sadia Quadri

Ngoc-Dung Dao

In an embodiment a method of feeding back channel state information from a beamformee device to a beamformer device is disclosed. The method comprises receiving, at a plurality of antennas of the beamformee device, signals from the beamformer device; constructing a beamforming matrix, the beamforming matrix spanning a vector subspace and indicating the signals received by each of the plurality of antennas of the beamformee device; determining a first feedback matrix that spans the vector subspace of the beamforming feedback matrix such that it can be compressed with a lower number of non-zero coefficients than the beamforming feedback matrix; compressing the first feedback matrix into a plurality of coefficients; and transmitting an indication of the plurality of coefficients to the beamformer device.

Wireless communication methods and apparatus

In an embodiment, a wireless communication method of transmitting a plurality of data streams from a transmitter to a receiver is disclosed. The transmitter comprises a plurality of antennas. The method comprises: encoding each of the data streams as a sequence of code words; determining a plurality of precoding transmit coefficients from channel information for each of a plurality of subcarriers, the precoding transmit coefficients defining spatial channels between the plurality of antennas of the transmitter and the receiver; determining a set of power loading factors for each spatial channel between the receiver and the transmitter, each set of power loading factors comprising a power loading factor for each of the plurality of subcarriers, by allocating power between the plurality of subcarriers to satisfy a signal to interference and noise target per code word; determining a signal for transmission by each antenna of the plurality of antennas by applying respective precoding coefficients and power loading factors to each respective sequence of code words; and transmitting each of the sequences of code words on a plurality of subcarriers of at least one of the spatial channels by transmitting the respective signals for transmission from each respective antenna.

In an embodiment, a method of managing distributed storage in a wireless network is disclosed. The wireless network comprises a plurality of data generating nodes, each data generating node configured to generate and store data symbols and parity symbols. The parity symbols depend on data symbols stored on other data generating nodes. The method comprises receiving indications of link quality estimates for wireless links between the data generating nodes; selecting an arrangement of an array code from a plurality of possible arrangements using the indications of link quality estimates, the array code depending on the number of data generating nodes in the plurality of data generating nodes and a required number of nodes from which all of the data symbols stored in the wireless network can be generated, the arrangement indicating for each data generating node, the dependence of the parity symbols stored on that data generating node on the data symbols stored on other data generating nodes; and sending an indication of the selected arrangement to the data generating nodes.

Reconfigurable encoding arrays for reduced outage probability sensor networks

A method of selecting a carrier frequency offset tracking pilot signal in an access point of a wireless network is disclosed. The wireless network includes the access point and a plurality of terminals. The method includes receiving, at a plurality of antennas of the access point, signals from each of the plurality of terminals; estimating, from the received signals, a spatial channel signature for each of the plurality of terminals; selecting, for each terminal of the plurality of terminals, using the spatial channel signatures, a carrier frequency offset tracking pilot signal for that terminal from a plurality of pre-coded pilot signals; and transmitting an indication of the selected carrier frequency offset tracking pilot signals to the respective terminal.

Carrier frequency offset estimation using precoded non-fixed pilot signals

An OFDM transmitter comprising an input for acquiring or receiving a signal to be transmitted, an output for transmitting a PAPR reduced version of the signal, a processor and memory storing code for execution by the processor. The processor, when executing the code, is configure to determine a plurality of possible values of tone reservation, hereinafter referred to as TR, tones for use in TR based PAPR reduction and to perform a tree search over some or all of the possible values under a first constraint that the average power per TR tone does not exceed the average power per tone used for data transmission and a second constraint that selected values for the TR tones reduce PAPR.

Tree search tone reservation for PAPR reduction in OFDM systems

A decoder for decoding a received set of blocks each including a plurality of data symbols and a plurality of parity symbols, wherein the received set of blocks is a subset of a complete set of blocks, the complete set of blocks including at least one erased block not included in the received set of blocks, the decoder including: a storage for a coding matrix which is the kronecker product of a totally non-singular matrix with an antidiagonal matrix; and a processor operable to determine data symbols of the at least one erased block using the encoding matrix.

Coding and decoding methods and apparatus

There is provided a device and method for demodulating a pulse amplitude modulated, hereinafter referred to as PAM, signal. The device comprises memory storing a set of boundaries of regions in which the log likelihood ratio, hereinafter referred to as LLR, for each bit to be determined is represented by a linear function of the received signal, along with the properties of the linear function for each bit for each region; and a controller. The controller is configured to: receive a PAM signal to be demodulated; determine which region the signal falls within; for each bit to be determined, retrieve the properties of the linear function for the LLR for the bit within the determined region and determine, from this linear function, the LLR value for the bit; and demodulate the signal based on the determined LLR values.

Demodulation of nonuniform QAM signals

A device for use in demodulating modulated signals by determining a value for a log likelihood ratio. The device has a storage device to store executable instructions and a processor to execute the instructions stored on the memory device. The processor is configured to, when executing the instructions: receive a modulated signal which is to be demodulated using a constellation diagram comprising a plurality of constellation points which are identified by binary reflected Gray-labelled codes; identify, for a bit of the Gray-labelled codes, a closest complementary constellation point to the signal when considering the signal as a point on a representation of one-dimension of the constellation diagram; identify a hard decision point, wherein the hard decision point is the closest constellation point to the signal when considering the signal as a point on a representation of one-dimension of a constellation diagram; and a complementary constellation point is a constellation point which has a different value for the bit compared to the hard decision point; and determine a value for a log likelihood ratio using the hard decision point and the closest complementary constellation point. Some devices identify a closest complementary constellation point to the signal, a second closest complementary constellation point to the signal, a hard decision point and an auxiliary hard decision point and determine a value for a log likelihood ratio using the hard decision point, an auxiliary hard decision point, the closest complementary constellation point and the second closest complementary constellation point.

Low-complexity LLR computation for nonuniform QAM constellations

In one embodiment a method of identifying interference in a wireless network is disclosed. The wireless network comprises a first base station and a second base station. The method comprises detecting an increase in an error rate in a wireless connection between the first base station and a first wireless device; comparing a reference signal power received by the first wireless device from the first base station with a threshold value; and determining that the increase in error rate is due to interference from a wireless connection between the second base station and a second wireless device if the reference signal power is greater than the threshold.

Processing data presented in the form of a vector representation involves representing direction of the vector with incremental accuracy by using a set of vector codebooks of decreasing dimensions per accuracy increment.

Wireless communication apparatus

A data compression process is described, for compressing channel state information to be fed back to a transmitter. The process involves arranging the data as a matrix comprising a number of orthonormal vectors derived from a channel matrix, determining a singular value decomposition of a subset of the orthonormal matrix to generate matrices respectively of left and right singular vectors, the number of vectors in the subset being equal to the order of the vectors, and right multiplying the remainder orthonormal vectors not included in the singular value decomposition by a matrix product of the matrix of right singular vectors and the matrix of left singular vectors to generate a matrix of compressed data.

Growing community of inventors

Bristol, United Kingdom

Filippo Tosato