Nokia Corporation

Ludwig Schwoerer

Ernst Zielinski

Andre Kaufmann

Jussi Vesma

Yuhuan Xu

André Kaufmann

There is being disclosed an OFDM signal receiver for detecting carrier frequency offset. When FFT transform of the signal is processed in the receiver, an estimator applies the spectrum shape of the FFT transform for estimating the carrier frequency offset.

FFT carrier frequency offset estimation for OFDM signal

An input bit stream is phase rotated by reversing bit pairs and inverting bits. The manipulated bit stream is mapped to a symbol and the mapped symbol is converted to the time domain such that an output of the time domain conversion is an ordered set of N samples that allow efficient cyclic prefix insertion without rotation at the symbol level. A first portion of the set of samples is stored in a buffer, and the complete set of samples is output followed by the buffered first portion of the set of samples for transmission. The set of samples can be Nsamples of an OFDM symbol and the first portion can be Nsamples that make up the cyclic prefix CP. Re-ordering the bits can be done by swapping bit pairs and inverting one of the swapped pairs, or by trivial (1, &#x2212;1, &#x2212;j) phase rotation. The buffer is &#xbc; the length of prior art OFDM buffers and CP-related processing delays are significantly reduced.

Frequency dependent phase rotation prior to mapping in an OFDM transmitter

The present invention relates to a method and apparatus for implementing a discrete Fourier transformation (DFT) of a predetermined vector size, wherein at least one enhanced DFT module is provided by using at least one type of DFT module including multiplication by first and second types of twiddle factors in respective different multiplication stages separated by an intermediate integration stage, and generating the enhanced DFT module by combining the at least one type of DFT module with a recursive stage configured to multiply by a third type of twiddle factor and to selectively switch between a bypass function and a butterfly function in said recursive stage. Thereby, an implementation of non 2-radix Fourier transformation can be achieved with moderate hardware complexity.

Optimized multi-mode DFT implementation

Mobile handheld terminals receiving DVB transmission require relatively low power consumption and TDM based transmission can be used to reduce power of the terminals. In order find pilot carrier position at least two symbols are accessed which are adapted to establish a correspondence pattern for pilot carriers in a matrix of the at least two symbols. Carriers of the first symbol are correlated with the corresponding carriers of the second symbol within the matrix for determining a correlation maximum for indicating a pilot carrier position.

Method, system and receiver in receiving a multi-carrier transmission

The present invention proposes a signal processor for Fast Fourier Transformation, FFT, of M, M&#x3e;1, input data streams of 2samples each, supplied in parallel. After multiplexing the input data streams in an interlaced manner, the resulting stream is subjected to FFT. The FFT device has a pipeline architecture composed of k stages with a respective feedback path including a single delay element per each stage of the pipeline architecture. The delay element and timing signals are adapted to cope with FFT processing of the multiplexed streams using the single FFT device only. After processing, the FFT processed data stream is demultiplexed. The present invention also concerns a corresponding signal processing method.

Growing community of inventors

Hattingen, Germany

Ludwig Schwoerer