Abstract: A method for controlling access to a resource, the method performed by a system comprising a first component, a second component and a third component, the first component comprising a first cryptographic key; the second component comprising a second cryptographic key. The method comprising: transmitting a signal; generating, by the first component a first channel observation; generating, by the second component, a second channel observation, and a first data value based on the second channel observation and the second cryptographic key; transmitting, by the second component, the second channel observation and the first data value; and verifying the second component based on the second channel observation, the first cryptographic key and the first data value; and allowing access to the resource in response to determining that the second component is: 1) permitted to gain access to the resource; and 2) located proximate to the first component.

Abstract: A method for controlling access to a resource, the method performed by a system comprising a first component, a second component and a third component, the first component comprising a first cryptographic key; the second component comprising a second cryptographic key. The method comprising: transmitting a signal; generating, by the first component a first channel observation; generating, by the second component, a second channel observation, and a first data value based on the second channel observation and the second cryptographic key; transmitting, by the second component, the second channel observation and the first data value; and verifying the second component based on the second channel observation, the first cryptographic key and the first data value; and allowing access to the resource in response to determining that the second component is: 1) permitted to gain access to the resource; and 2) located proximate to the first component.

Abstract: A method comprising transmitting, by a first communication node (101), a first communication; receiving, by a relay node (103; 503), the first communication and estimating a first communication channel (Hk; Hk(1)). Transmitting, by a second communication node (102), a second communication; receiving, by the relay node (103; 503), the second communication; and estimating a second communication channel (Gk, Gk(1)); generating a first transmission signal (xk; x1); transmitting, by the relay node (103; 503), the first transmission signal (xk; x1); generating, by the first communication node (101), a first instance of the encryption key (?A) based on a first received signal (rA); generating, by the second communication node (102), a second instance of the encryption key (?B) based on a second received signal (rB), wherein: the transmission signal (xk) is generated such that the first received signal (rA) is equal to the second received signal (rB).

Abstract: A method of operating a first node to generate a secret key for encrypting wireless transmissions between the first node and a second node. The method comprises receiving a first training signal comprising a plurality of subcarriers from the second node and constructing a matrix from the frequency responses of each of the plurality of subcarriers of the first training signal at the first node. A singular value decomposition of the matrix is computed; and a secret key is derived from one or more singular vectors of the singular value decomposition.

Abstract: A method comprising transmitting, by a first communication node (101), a first communication; receiving, by a relay node (103; 503), the first communication and estimating a first communication channel (Hk; Hk(1)). Transmitting, by a second communication node (102), a second communication; receiving, by the relay node (103; 503), the second communication; and estimating a second communication channel (Gk, Gk(1)); generating a first transmission signal (xk; x1); transmitting, by the relay node (103; 503), the first transmission signal (xk; x1); generating, by the first communication node (101), a first instance of the encryption key (KA) based on a first received signal (rA); generating, by the second communication node (102), a second instance of the encryption key (KB) based on a second received signal (rB), wherein: the transmission signal (xk) is generated such that the first received signal (rA) is equal to the second received signal (rB).

Abstract: A method for active gate driving a switching circuit, wherein: a characteristic of a waveform controlled by the switching circuit is represented by a function mapping an input variable to an output metric, and wherein: the input variable comprises: a design variable having a first set of possible values; and an environmental variable having a second set of possible values, wherein the environmental variable is observable but not controllable. The method comprising: performing Bayesian optimisation on the function to generate a model of the function, wherein a next value of the design variable for evaluating the function is selected based on values of an acquisition function associated with a predicted value of the environmental variable; determining a first value of the design variable that optimises the model of the function; and controlling the switching circuit according to the first value of the design variable.

Abstract: A method of transmitting packets between a plurality of nodes of a network. The method comprising in each of a plurality of data timeslots, transmitting a data packet with one of the plurality of nodes and listening to receive the data packet with the remainder of the plurality of nodes. The method further comprising in each of one or more parity timeslots following the plurality of data timeslots, transmitting a parity packet with one or more of the plurality of nodes and listening to receive the parity packet with the remainder of the plurality of nodes. Each parity packet is derived from a set of the data packets transmitted during the plurality of data timeslots.

Abstract: A method of operating a first node to generate a secret key for encrypting wireless transmissions between the first node and a second node. The method comprises receiving a first training signal comprising a plurality of subcarriers from the second node and constructing a matrix from the frequency responses of each of the plurality of subcarriers of the first training signal at the first node. A singular value decomposition of the matrix is computed; and a secret key is derived from one or more singular vectors of the singular value decomposition.

Abstract: A method for storing input data in a flash memory. The method comprising generating a codeword by encoding the input data with an error correcting code and generating a shaped codeword by applying a shaping function to at least a part of the codeword. The shaping function comprising logically inverting every n-th occurrence of a bit associated with a high-charge storage state in the part of the codeword. The method further comprising writing the shaped codeword to the flash memory, generating an estimated shaped codeword by reading the flash memory, generating soft decision information for the estimated shaped codeword, and retrieving the input data by decoding the soft decision information using an error correcting code soft decoder.

Abstract: A method for storing input data in a flash memory. The method comprising generating a codeword by encoding the input data with an error correcting code and generating a shaped codeword by applying a shaping function to at least a part of the codeword. The shaping function comprising logically inverting every n-th occurrence of a bit associated with a high-charge storage state in the part of the codeword. The method further comprising writing the shaped codeword to the flash memory, generating an estimated shaped codeword by reading the flash memory, generating soft decision information for the estimated shaped codeword, and retrieving the input data by decoding the soft decision information using an error correcting code soft decoder.

Abstract: A method of soft decoding received signals. The method comprising defining quantisation intervals for a signal value range, determining a number of bits in each quantisation interval that are connected to unsatisfied constraints, providing, the number of bits in each quantisation interval that are connected to unsatisfied constraints, as an input to a trained model, wherein the trained model has been trained to cover an operational range of a device for soft decoding of signals, determining, using the trained model, a log likelihood ratio for each quantisation interval, and performing soft decoding using the log likelihood ratios.

Abstract: A method of soft decoding received signals. The method comprising defining quantisation intervals for a signal value range, determining a number of bits in each quantisation interval that are connected to unsatisfied constraints, providing, the number of bits in each quantisation interval that are connected to unsatisfied constraints, as an input to a trained model, wherein the trained model has been trained to cover an operational range of a device for soft decoding of signals, determining, using the trained model, a log likelihood ratio for each quantisation interval, and performing soft decoding using the log likelihood ratios.

Abstract: A method of transmitting packets between a plurality of nodes of a network. The method comprising in each of a plurality of data timeslots, transmitting a data packet with one of the plurality of nodes and listening to receive the data packet with the remainder of the plurality of nodes. The method further comprising in each of one or more parity timeslots following the plurality of data timeslots, transmitting a parity packet with one or more of the plurality of nodes and listening to receive the parity packet with the remainder of the plurality of nodes. Each parity packet is derived from a set of the data packets transmitted during the plurality of data timeslots.

Abstract: A method of generating soft decision detection parameters for a plurality of received signals. The method comprises defining a hard decision boundary and a plurality of quantisation intervals wherein each quantisation interval extends from the hard decision boundary by an interval distance, selecting a log likelihood value from a set of log likelihood values for each received signal based on the quantisation interval in which the received signal is detected, performing a soft decoding using a plurality of log likelihood values, adjusting the set of log likelihood values based on a result of the soft decoding, determining an error probability for a quantisation interval, comparing the error probability against a target error probability and adjusting the interval distance in order to obtain the target error probability.

Abstract: A method of storing a number of data values in a plurality of flash memory cells wherein each flash memory cell has a plurality of storage states and each data value is selected from a set of possible data values. The method comprises programming the number of data values to the plurality of flash memory cells using a mapping which uniquely associates each combination of storage states for the plurality of flash memory cells with a concatenated data value from a set of concatenated data values wherein the set of concatenated data values comprises a concatenated data value for every combination of possible data values for the number of data values, the concatenated data value has a position for each data value in the number of data values and the mapping is such that between adjacent storage states all but one data values are identical and each position in the concatenated data value changes the data value it represents between the same storage states on each flash memory cell.

Abstract: A method of decoding data stored in non-volatile memory in which each memory cell stores data by adopting one of a plurality of storage states.

Abstract: A method of generating soft decision detection parameters for a plurality of received signals. The method comprises defining a hard decision boundary and a plurality of quantisation intervals wherein each quantisation interval extends from the hard decision boundary by an interval distance, selecting a log likelihood value from a set of log likelihood values for each received signal based on the quantisation interval in which the received signal is detected, performing a soft decoding using a plurality of log likelihood values, adjusting the set of log likelihood values based on a result of the soft decoding, determining an error probability for a quantisation interval, comparing the error probability against a target error probability and adjusting the interval distance in order to obtain the target error probability.

Abstract: A computer-implemented method of estimating IQ imbalance in a communication system including a transmitter and a receiver. The method includes: defining a system model in which a transmitted signal is affected by TX IQ imbalance, carrier frequency offset (CFO) and RX IQ imbalance; controlling a local oscillator at the transmitter to introduce a known carrier frequency offset (CFO) during a calibration; and estimating unknown parameters in the system model using a pre-defined training sequence to determine the TX IQ imbalance and the RX IQ imbalance.

Abstract: A method of soft decoding received signals. The method comprises defining quantisation intervals for a signal value range, determining a number of bits detected in each quantisation interval, a number of bits in each quantisation interval that are connected to unsatisfied constraints and a probability that the error correction code is unsatisfied, determining an overall bit error rate based on the probability that the error correction code is unsatisfied, determining a log likelihood ratio for each quantisation interval based on the overall bit error rate, the number of bits detected in each quantisation interval and the number of bits in each quantisation interval that are connected to unsatisfied constraints and performing soft decoding using the log likelihood ratios.

Abstract: A method of decoding data stored in non-volatile memory in which each memory cell stores data by adopting one of a plurality of storage states.