Symbol Based Precoding in the Downlink of Cognitive MISO Channel

This paper proposes symbol level precoding in the downlink
of a MISO cognitive system. The new scheme tries to jointly utilize the
data and channel information to design a precoding that minimizes the
transmit power at a cognitive base station (CBS); without violating the
interference temperature constraint imposed by the primary system. In
this framework, the data information is handled at symbol level which
enables the characterization the intra-user interference among the cog-
nitive users as an additional source of useful energy that should be ex-
ploited. A relation between the constructive multiuser transmissions and
physical-layer multicast system is established. Extensive simulations are
performed to validate the proposed technique and compare it with con-
ventional techniques