Symbol Based Precoding in The Downlink of Cognitive MISO Channels

TL;DR

This paper introduces a symbol-level precoding scheme for cognitive MISO downlink systems that minimizes transmit power by exploiting intra-user interference as useful energy while respecting interference constraints.

Contribution

It presents a novel symbol-level precoding method that jointly uses data and channel info to reduce power and improve efficiency in cognitive MISO systems.

Findings

The proposed scheme reduces transmit power compared to conventional methods.

Intra-user interference is exploited as a beneficial energy source.

Simulations validate the effectiveness of the new precoding technique.

Abstract

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 cognitive users as an additional source of useful energy that should be exploited. 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 conventional techniques.