In 60 GHz WiGig/IEEE 802.11ad, Orthogonal Frequency Division Multiplexing (OFDM) is used to achieve higher throughput. However, OFDM has one problem of high Peak-to-Average Power Ratio (PAPR) caused by the summing up of the large number of subcarriers. A high PAPR signal degrades the efficiency of power amplifier (PA) and may cause spurious emissions because of the PA non linearity. In order to reduce PAPR, Generalized Frequency Division Multiplexing (GFDM) which has the characteristics of both single carrier and multi carrier transmission has been studied. By introducing GFDM, the number of subcarriers can be decreased while still maintaining a high throughput.

A method for FFT/IFFT computation, comprising: identifying whether grouping data is needed based on data bitwidth distribution in a set of data, wherein the set of data includes data in a stage of a FFT/IFFT computation; assigning different data representations including effective bit and group index for data identified in different groups if grouping is needed, wherein data in a group have same exponent, and data in different groups have different exponents; and outputting a signal indicating the exponent; for each of a plurality of short sequence FFT/IFFT computation—decomposing data used in present short sequence FFT/IFFT computation into at least a first multi-bit part and a second multi-bit part; respectively calculating FFT/IFFT computation results for the first multi-bit part and the second multi-bit part; adding the FFT/IFFT computation results for the first and the second multi-bit part; scanning a plurality of short sequence FFT/IFFT computation added results.

System and methods enabling radio communications that are operating in noisy environments using OFDM (Orthogonal Frequency Division Multiplexing) are disclosed. A spread OFDM transmitter that generates OFDM symbols that may include multiple copies of IFFT symbols is disclosed. A spread OFDM receiver is disclosed for receiving the spread OFDM symbols. Other methods for symbol detection, frequency offset correction, and equalization are disclosed.

A system includes a hardware accelerator configured to perform a two-dimensional (2D) fast Fourier transform (FFT) on an M×N element array. The hardware accelerator has log.sub.2 M×N pipeline stages including an initial group of log.sub.2 M stages and a final group of log.sub.2 N stages. Each stage includes a butterfly unit, a FIFO buffer coupled to the butterfly unit, and a multiplier coupled to the butterfly unit and to an associated twiddle factor table. The hardware accelerator also includes butterfly control logic to provide elements of the M×N element array to the initial group of stages in an N direction of the array, and twiddle factor addressing logic to, for the twiddle factor tables of the initial group of stages, apply an indexed entry of the twiddle factor table to the associated multiplier. The indexed entry begins as a first entry and advances by N entries after every N cycles.

Methods and systems for modulating and demodulating data in systems is described. An Inverse Fast Fourier Transform (FFT) can be applied to complex-valued symbols that represent bit groups. The FFT can be replaced with a Fast Accurate Fourier Transform (FAFT) that can comprise variable size signal windows.

In an operation in a license-exempt band (unlicensed band), the present invention contributes to the provision of a mobile station, a base station, a transmission method and a receiving method which suitably transmit and receive a signal. The mobile station 200 includes: a transmission unit 205 which transmits an uplink signal; and a control unit 201 which, when a first number indicating a first resource amount that can be used in the transmission of the uplink signal includes a third number, which is different from a specific second number, as a prime factor, controls the transmission of a signal of a fourth number that does not include the third number as the prime factor by using a second resource.

A system includes a hardware accelerator configured to perform a two-dimensional (2D) fast Fourier transform (FFT) on an M×N element array. The hardware accelerator has log.sub.2 M×N pipeline stages including an initial group of log.sub.2 M stages and a final group of log.sub.2 N stages. Each stage includes a butterfly unit, a FIFO buffer coupled to the butterfly unit, and a multiplier coupled to the butterfly unit and to an associated twiddle factor table. The hardware accelerator also includes butterfly control logic to provide elements of the M×N element array to the initial group of stages in an N direction of the array, and twiddle factor addressing logic to, for the twiddle factor tables of the initial group of stages, apply an indexed entry of the twiddle factor table to the associated multiplier. The indexed entry begins as a first entry and advances by N entries after every N cycles.

One example discloses an OFDM wireless communications device, including: a memory configured to support processing of OFDM tones; a controller, coupled to the memory, and configured to set the wireless communication device to a first mode and a second mode; wherein the first mode is configured to transmit or receive a first wireless communication signal having a first set of OFDM tones contained within an OFDM channel bandwidth; wherein the second mode is configured to transmit or receive a second wireless communication signal having a second set of OFDM tones contained within the OFDM channel bandwidth; and wherein the memory used for processing the first set of OFDM tones is same as the memory used for processing the second set of OFDM tones.

A transmitter includes: a frame generator configured to generate a frame including a frame starting symbol, at least one data symbol and a frame closing symbol; a pilot and reserved tone inserter configured to insert pilots and reserved tones in at least one of the frame starting symbol, the data symbol and the frame closing symbol such that positions of the reserved tones do not overlap positions of the pilots in the at least one of the frame starting symbol, the data symbol and the frame closing symbol; and a transmitter configured to transmit the frame in which the pilots and the reserved tones are inserted, wherein the reserved tones are not used to transmit data in the frame.

A transmitter includes: a frame generator configured to generate a frame including a frame starting symbol, at least one data symbol and a frame closing symbol; a pilot and reserved tone inserter configured to insert pilots and reserved tones in at least one of the frame starting symbol, the data symbol and the frame closing symbol such that positions of the reserved tones do not overlap positions of the pilots in the at least one of the frame starting symbol, the data symbol and the frame closing symbol; and a transmitter configured to transmit the frame in which the pilots and the reserved tones are inserted, wherein the reserved tones are not used to transmit data in the frame.