Patent ID: 8116195
Filing Date: 2012-02-14
Classification: H04J,H04L

Abstract:
1. A method for communications based on orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA), comprising: selecting an initial constant amplitude zero autocorrelation (CAZAC) sequence; producing a first sequence by setting one or more amplitudes of respective one or more frequency components in a portion of the initial CAZAC sequence to zero and adding a first phase shift factor for one or more frequency components in another portion of the initial CAZAC sequence, producing a second, different sequence by setting one or more amplitudes of respective one or more frequency components in a different portion of the initial CAZAC sequence to zero and adding a second phase shift factor for one or more frequency components in the another portion of the initial CAZAC sequence, where the second phase shift factor is the inverse of the first phase shift factor, joining the first sequence and the second sequence, such that they are connected, to generate a modified sequence; and using the modified sequence as part of a preamble of a downlink signal from a base station to a mobile station.