Patent ID: 6188717
Filing Date: 2001-02-13
Classification: H04B,H04J,H04L

Abstract:
A method which uses a combination of the multi-carrier modulation method, a plurality of sub-carriers in a frequency band for modulation, and the spread spectrum technique, said method being for simultaneous radio transmission of digital data between a plurality of subscriber stations and a base station, said method comprising:transmitting reference symbols for channel estimation to be performed on a receiving side, wherein on transmission side the digital data of a subscriber station are spread prior to transmission such that they are modulated with a set of orthogonal spread sequences and superimposed with them;then transmitting the spread data of a subscriber station, in modulated form, on a partial quantity of sub-carriers in a multi-carrier frequency band, wherein the partial quantities of sub-carriers associated with the individual subscriber stations being disjunct and distributed over an entirety of the frequency band; andinserting the reference symbols, which are known to the receiving side, into a sub-carrier data stream of each respective subscriber station associated therewith, for channel estimation;multi-carrier demodulating and separating, on the receiving side, the received digital data with regard to the respective subscriber station sub-carrier;extracting from the information-carrying data the reference symbols, for channel estimation for each sub-carrier to be detected and for deriving channel-state information that is necessary for later data detection and channel decoding for the respective information-carrying data;detecting together, with a suitable de-spreading detection method, the information-carrying digital data of a subscriber station;wherein the sub-carriers of a subscriber station are distributed over an entirety of the transmission-frequency band;wherein spacing between adjacent sub-carriers of a subscriber station is a multiple factor of a reciprocal value of a duration of a multi-carrier modulated data symbol; andwherein the sub-carriers are distinguished for the respective subscriber station at a particular frequency and time.