Abstract: A technique for allowing a linear feedback shift register (LFSR), and particularly a Galois LFSR, to be advanced forward by an amount m (i.e. as if the register had undertaken m input/output cycles), without actually having to undertake m input/output cycles is described. This is useful for example in the communications domain by allowing the shift register to be able to jump to a particular scrambling code. In particular, an embodiment provides an apparatus which is able to control the advance of a LFSR by feeding into the LFSR a data word obtained from the polynomial multiplication of two predetermined data words which are looked up from one or more tables in dependence on an advance amount, being the number of steps the LFSR is to advance. The state of the LFSR after the data word has been fed into the LFSR is then the same state the LFSR would be in if it had actually been advanced by the advance amount.

Abstract: A wireless communications device comprising duplexing means for directing signals from a transmit path towards an antenna and for providing signals from the antenna to a receive path, wherein the transmit path is arranged to send a first signal to the duplexing means, the receive path is arranged to recover a second signal and the device further comprises detecting means for detecting the presence in the receive path of a third signal that will interact with the first signal to produce intermodulation distortion tending to hamper recovery of the second signal and control means responsive to the detecting means for enhancing linearity in the receive path to reduce said intermodulation distortion.

Abstract: The invention provides a receiver that is capable of deducing the timing of a received signal having a frame structure and corresponding methods. Each frame contains a synchronization word. The receiver correlates the known synchronization word against the received signal to determine the position of the synchronization word. The correlation results can be accumulated over several frames' worth of the signal in order to enhance the determination. The frame boundaries within the signal can be translated and the process of determining the synchronization word position can then be repeated. In this manner, several results for the synchronization word position can be obtained and the best selected. A thresholding process can be used to curtail the number of frames' worth of the received signal that needs to be processed and a mechanism is provided to prevent the thresholding process from biasing the determination of the synchronization word position.

Abstract: A method of classifying a ray is disclosed, the ray being received at a code division multiple access receiver. The method comprises: determining if a timing characteristic of the ray falls within a predetermined range of a timing characteristic of a ray classified to a given cell; in response to a positive determination, mixing a received signal with a scrambling code used by the given cell to provide a mixed signal; and examining the mixed signal to determine if the ray originates from the given cell.

Abstract: Datawords encoded using a first-order Reed-Muller code are decoded using a Fast Hadamard Transform (FHT). Where the dataword is known to comprise a number of unused bits at one end, the soft decisions of the codeword are reordered. Majority polling is then performed on groups of the soft decisions to produce a series of soft decisions which make up a new codeword. The new codeword is then decoded using an FHT of lower order than the FHT applicable to the originally received codeword.

Abstract: The circuit (10) performs a butterfly calculation for a Viterbi trellis by using two path metrics and a branch metric to generate two new path metrics. The new metrics are produced by adders (12) and (14) whose inputs are controlled by selectors (16-22). The outputs of the selectors (16-22) are controlled by selection control unit (24) which considers the difference between the given path metrics relative to the double of the branch metric, which represents a branch metric difference.

Abstract: A stream of recursive systematic convolutional codes Pn is generated by XORing each bit of an input bit stream In with a predetermined bit of the content of a cyclic shift element (22). The content of the shift element (22) is updated by adder (24) under the control of the input bit stream In.

Abstract: The processor (24) retrieves from a memory (22) values of a signal recovered from received wireless signal and demultiplexes and de-interleaves them simultaneously. The system can be operated in reverse to produce a multiplexed, interleaved data stream for wireless transmission.