Design and analysis of a DCSK-based cognitive radio system using hybrid underlay/overlay transmission

Multivariable optimisation approach for power allocation in OFDM‐DCSK system

“…To the best of our knowledge, there are very few articles investigating power allocation in the OFDM-DCSK systems [13][14][15]. Thus, in this paper, we focus on the OFDM-DCSK system presented in [14] to change a non-optimal single-variable problem into a multivariable problem.…”

“…A similar strategy with interference consideration has been introduced in [15]. However, in both [14,15], the power allocated to the reference sub-carrier has been assumed to be equal to one to simplify the problem to a single-variable optimisation problem. In other words, the optimal power for the reference subcarrier has not been calculated in the literature so far.…”

“…(1) In contrast with [13][14][15], we do not relax the reference power and consider this variable as an important and decisive parameter. In other words, we aim to simultaneously, find the optimal power for the reference and data-bearing subcarriers to minimise the BER performance of the OFDM-DCSK system.…”

“…Some studies have focused on the power allocation in OFDM-DCSK system, and several optimisation strategies have been proposed in the literature such as BER minimisation and min-max BER strategy. However, all of them have only addressed the case where the power allocated to the reference subcarrier is assumed to be equal to one to simplify the problem to a single-variable optimisation problem [13][14][15]. In this paper, we formulate a multivariable optimisation problem and solve it using Lagrange relaxation to derive a closed form solution for power allocation in OFDM-DCSK system, offering better performance by jointly determining the power of the reference and data-bearing subcarriers.…”