A system and method for communicating information signals using spread
spectrum communication techniques. PN sequences are constructed that
provide orthogonality between the users so that mutual interference will
be reduced, allowing higher capacity and better link performance. With
orthogonal PN codes, the cross-correlation is zero over a predetermined
time interval, resulting in no interference between the orthogonal codes,
provided only that the code time frames are time aligned; with each other.
In an exemplary embodiment, signals are communicated between a cell-site
and mobile units using direct sequence spread spectrum communication
signals. In the cell-to-mobile link, pilot, sync, paging and voice
channels are defined. Information communicated on the cell-to-mobile link
channels are, in general, encoded, interleaved, bi-phase shift key (BPSK)
modulated with orthogonal covering of each BPSK symbol along with
quadrature phase shift key (QPSK) spreading of the covered symbols. In the
mobile-to-cell link, access and voice channels are defined. Information
communicated on the mobile-to-cell link channels are, in general, encoded,
interleaved, orthogonal signaling along with QPSK spreading.
