A method of transmitting a Physical Layer Convergence Procedure (PLCP) frame in a Very High Throughput (VHT) Wireless Local Area Network (WLAN) system includes generating a MAC Protocol Data Unit (MPDU) to be transmitted to a destination station (STA), generating a PLCP Protocol Data Unit (PPDU) by adding a PLCP header, including an L-SIG field containing control information for a legacy STA and a VHT-SIG field containing control information for a VHT STA, to the MPDU, and transmitting the PPDU to the destination STA. A constellation applied to some of Orthogonal Frequency Division Multiplex (OFDM) symbols of the VHT-SIG field is obtained by rotating a constellation applied to an OFDM symbol of the L-SIG field.

A Bluetooth receiver is provided. The Bluetooth receiver comprises processing circuitry configured to receive a receive signal and to determine receive symbols based on the receive signal. The Bluetooth receiver further comprises control circuitry configured to determine a frequency offset and/or a modulation index of the receive signal based on the receive signal. The control circuitry is additionally configured to control an operation mode of the processing circuitry based on the determined frequency offset and/or the modulation index of the receive signal.

An apparatus for demodulating a frequency-modulated signal comprises a joint frequency-offset & modulation-index estimator, and a signal demodulator. The joint estimator receives data representative of a preamble portion of the signal, modulated with predetermined preamble data. It jointly determines a frequency-offset estimate and a modulation-index estimate by using an optimization process that minimizes a cost function that is a function of the received data and that is parameterised by a frequency-offset parameter and by a modulation-index parameter. The signal demodulator receives data representative of a message portion of the signal, modulated with message data, and uses the frequency-offset estimate to demodulate the message.

An apparatus for demodulating a frequency-modulated signal comprises a joint frequency-offset & modulation-index estimator, and a signal demodulator. The joint estimator receives data representative of a preamble portion of the signal, modulated with predetermined preamble data. It jointly determines a frequency-offset estimate and a modulation-index estimate by using an optimization process that minimizes a cost function that is a function of the received data and that is parameterised by a frequency-offset parameter and by a modulation-index parameter. The signal demodulator receives data representative of a message portion of the signal, modulated with message data, and uses the frequency-offset estimate to demodulate the message.

A method for processing an electrical signal comprises receiving an electrical signal comprising a frequency modulated signal encoding digital data; sampling a first portion of the electrical signal to obtain a plurality of samples to obtain a first sample set; determining an index value from the first sample set by assigning a value to each sample in the first sample set based upon an amplitude of the sample; comparing the determined index value with a plurality of predetermined index values to identify a first output value from a plurality of predetermined output values, each of the predetermined index values corresponding to one of the plurality of predetermined output values; and outputting an indication of the output value. Each of the predetermined output values indicates a respective frequency modulation encoded value and the first output value indicates a frequency modulation encoded value within the first portion of the electrical signal.

A method of operating a digital radio receiver is provided as follows: a) receiving a radio signal comprising a symbol sequence; b) selecting a portion of the symbol sequence; c) determining a first error between the selected portion of the symbol sequence and a first predetermined symbol sequence using a difference metric; d) determining a set of second errors between the selected portion of the symbol sequence and a respective set of second predetermined symbol sequences, each formed by prepending different length portions of a predetermined preamble symbol sequence to a beginning of the first predetermined symbol sequence; and e) determining a minimum error from the first error and the set of second errors. If the first error is not the minimum error, a different portion of the symbol sequence is selected. Otherwise, a following portion of the symbol sequence is decoded to produce a data payload.

A method of operating a digital radio receiver is provided as follows: a) receiving a radio signal comprising a symbol sequence; b) selecting a portion of the symbol sequence; c) determining a first error between the selected portion of the symbol sequence and a first predetermined symbol sequence using a difference metric; d) determining a set of second errors between the selected portion of the symbol sequence and a respective set of second predetermined symbol sequences, each formed by prepending different length portions of a predetermined preamble symbol sequence to a beginning of the first predetermined symbol sequence; and e) determining a minimum error from the first error and the set of second errors. If the first error is not the minimum error, a different portion of the symbol sequence is selected. Otherwise, a following portion of the symbol sequence is decoded to produce a data payload.

A Bluetooth receiver is provided. The Bluetooth receiver comprises processing circuitry configured to receive a receive signal and to determine receive symbols based on the receive signal. The Bluetooth receiver further comprises control circuitry configured to determine a frequency offset and/or a modulation index of the receive signal based on the receive signal. The control circuitry is additionally configured to control an operation mode of the processing circuitry based on the determined frequency offset and/or the modulation index of the receive signal.

A transmission device that wirelessly communicates with a reception device includes an FSK modulation unit that performs frequency shift keying modulation on an input information bit sequence to generate a frequency shift keying symbol, a direct-sequence spreading unit that spreads the frequency shift keying symbol by direct-sequence spreading using a chirp sequence, and an FSK carrier spacing control unit that controls a signal to be transmitted to the reception device in such a manner as to prevent a delayed-wave component in multipath propagation from appearing in a frequency shift keying candidate carrier in one symbol of two consecutive symbols, in a frequency spectrum of a signal obtained by despreading in the reception device.

A transmission device that wirelessly communicates with a reception device includes an FSK modulation unit that performs frequency shift keying modulation on an input information bit sequence to generate a frequency shift keying symbol, a direct-sequence spreading unit that spreads the frequency shift keying symbol by direct-sequence spreading using a chirp sequence, and an FSK carrier spacing control unit that controls a signal to be transmitted to the reception device in such a manner as to prevent a delayed-wave component in multipath propagation from appearing in a frequency shift keying candidate carrier in one symbol of two consecutive symbols, in a frequency spectrum of a signal obtained by despreading in the reception device.