Primary Interference Suppression in Secondary Underlay Transmission Using Direct Sequence Spread Spectrum

In secondary underlay transmission in a host channel, the signal from primary transmitter produces high interference for secondary low power links. In this paper, we propose a primary interference suppression technique by using direct sequence spread spectrum. We show that secondary users can efficiently suppress the high power signal from a primary transmitter by using proper processing gains. Also, we propose a simple deployed underlay transmission scheme in a host channel for a secondary network. We show that by using primary interference suppression for direct sequence spread spectrum links our proposed transmission scheme achieves 186.09 Mbps and 362.73 Mbps capacity respectively at the center and at the edge of a primary cell when there are 60 secondary channel applicants in secondary network and processing gain is 100. Also, we show that the achieved capacity is gained without producing harmful interference temperature in the host channel and perceptible interference in adjacent channels.