Patent ID: 6810073
Filing Date: 2004-10-26
Classification: H04B

Abstract:
A method for canceling interference in a code division multiple access (CDMA) communication system to recover a signal encoded in a CDMA transmission, comprising the steps of:transmitting on a particular channel the CDMA transmission having a specific signal encoded therein, said specific signal including a plurality of symbols, each symbol having an associated spreading factor, and said specific signal spread using a particular spreading sequence, wherein the length of the spreading sequence differs from at least one of the associated spreading factors, the spreading sequence comprises a repeating short spreading sequence, and said CDMA transmission includes at least one other signal encoded therein; receiving the CDMA transmission having the specific signal encoded therein; filtering the CDMA transmission using a plurality of despreading sequences to recover the specific signal, wherein each of the plurality of despreading sequences corresponds to a particular portion of the spreading sequence and a first subset of the plurality of despreading sequences is associated with a first spreading factor and a second subset of the plurality of despreading sequences is associated with a second spreading factor, wherein said first spreading factor differs from said second spreading factor and wherein the first subset of the despreading sequences consists of a number of despreading sequences equal to a length of the particular spreading sequence divided by the first spreading factor and the second subset of the despreading sequences consists of a number of despreading sequences equal to a length of the particular spreading sequence divided by the second spreading factor, each symbol despread using at least one of the plurality of despreading sequences, said at least one of the plurality of despreading sequences selected for each symbol according to the portion of the spreading sequence used to spread that symbol; and adapting each despreading sequence to cancel interference associated with the portion of the spreading sequence that corresponds to said despreading sequence, said interference caused by the at least one other signal.