Abstract:
Aparato 100 para estimar un canal y realizar una igualación en un esquema de modulación de OFDM en el que un símbolo de bloque recibido r{sup,ig}(k) incorpora un prefijo redundante r{sup,gi}{sub,0}(k), r{sup,gi}{sub,1}(k), r{sup,gi}{sub,2}(k),... r{sup,gi}{sub,D-1(k) además de los datos útiles a enviar, comprendiendo el aparato medio de almacenamiento y detección de prefijo redundante 60, 70 para detectar y almacenar el prefijo redundante además de los datos útiles y medios de procesamiento 110 para procesar el prefijo redundante para derivar información ^C{sub,0}, ^C{sub,1},...^C{sub,D} alrededor del canal.
Abstract:
Received signals are sampled (307) and after serial/parallel conversion (309), supplied to a demodulator (311) applying a discrete Fourier transformation. The DFT output values are then preferably compared to a threshold in an isolation stage (313), those falling below it being discarded. The wanted signal components are then demultiplexed (315) for subsequent decoding. Independent claims are included for a telecommunications system operating with a maximum band width, and for a method of receiving signals in a radio system operating with different signal bandwidths.
Abstract:
A transmitter comprises a transmit processor (105), preamble inserters (107, 109) and transmit units (113, 117) which are operable to transmit sub-signals from the antennas (115, 119). A preamble set comprising an individual preamble for each antenna generated by a preamble generator (111). Each of the individual preambles comprise first and second sections. The first section comprises a first data sequence, different for each antenna, and is selected from a predetermined set of preamble sequences. The first data sequence may comprise only time domain symbols belonging to the alphabet [1,-1, i,-i,0]. The second section comprises repetitions of a predetermined second data sequence where each repetition is weighted by a coefficient that is different for each antenna. Weighting may be by coefficients of different rows of a Walsh Hadamard matrix. The second data sequence may comprise only frequency domain symbols belonging to the alphabet of [1,-1,0].
Abstract:
A method of channel estimation comprises the steps of receiving a signal and applying a fast fourier transform (FFT) to obtain a plurality of frequency domain sub-carriers. Probabilities of coded bits are produced and channel coefficient estimation is performed for each of the plurality of frequency domain sub-carriers usung channel coefficient estimates of other ones (preferably all others) of the plurality of frequency domain sub-carriers, which are based on the probabilities on coded bits. An OFDM communication unit and OFDM communication system are also provided.