Method and apparatus for transmission and construction of quasi

Abstract

A transmission method in a communications system having orthogonal code vectors for transmitting message signals is taught. The method includes forming a first vector matrix using a first series of cyclic shifts and forming a second vector matrix using a second series of cyclic shifts. The first vector matrix is permuted to provide an orthogonal code and the permuting operations are determined. The method also sets forth applying the determined permuting operations to the second matrix to provide a quasi orthogonal code vector. The quasi orthogonal code vector is applied to a message signal to provide an encoded message signal and the encoded message signal is transmitted. The forming of the first matrix vector includes cyclic shifts of a sequence having a characteristic polynomial. The characteristic polynomial of the sequence can be a primitive polynomial with a degree r. The sequence is an m-sequence. The length of the orthogonal code vector is n=2.sup.r and the forming of the first vector matrix can require n-1 cyclic shifts. The first matrix is extended prior to permuting. The primitive polynomial is lifted to a quaternary polynomial. A sequence having the quaternary polynomial is as its characteristic polynomial is generated whereby the sequence thus formed is a Family A sequence and the step of forming the second matrix is formed according to the Family A sequence. The second matrix is also extended prior to permuting the second matrix. The second vector matrix is permuted to provide a mask and the mask is applied to an orthogonal code vector to provide the quasi orthogonal vector. The mask can be applied to a plurality of orthogonal vectors to provide a plurality of quasi orthogonal vectors.