Efficient sidelobe suppression for OFDM systems using advanced cancellation carriers

Abstract

The concept of cancellation carriers (CCs) has been proposed in the literature for sidelobe suppression for orthogonal frequency division multiplexing (OFDM) systems. Subcarriers at the edges of the OFDM spectrum are used for sidelobe reduction while the remaining subcarriers are used for data transmission. Existing CCs techniques require performing complex optimization that should be applied for each OFDM symbol which is not suitable for real-time applications. In this paper, we propose a heuristic approach for CCs. The proposed algorithm involves few computations compared with all other techniques proposed in the literature. Simulation results show that sidelobe reduction performance can be close to the optimal. Moreover, the proposed algorithm is implemented in a software defined radio and implementation results prove that it can be introduced for real-time applications.

Sidelobe Reduction in Non-Contiguous OFDM-Based Cognitive Radio Systems Using a Generalized Sidelobe Canceller

“…The SU operating in region II has 16 subcarriers, region IV has 32, region VI has 64, and SU, operating in region VIII, has 128 subcarriers, modulated with BPSK, whose power is normalized to |dn| 2 = 1. The performance of the proposed technique is compared with different existing techniques including CC [14], CC using GA and DE [17], ACC [18], and ASW [21]. In CC techniques, two CCs have been taken on either side of the data subcarriers, and in SW techniques all subcarriers are used for suppression.…”

“…Each SU has 32 OFDM subcarriers. Figures 10 and 11 show the comparison of the proposed technique with already existing sidelobe suppression techniques including CC [14], CC using GA and DE [17], ACC [18], and ASW [21]. In all CC techniques, two CCs have been taken on both sides of the data subcarriers.…”

“…The bandwidth allocated to each PU is considered equal in all regions. The comparison of the proposed technique is done with already existing techniques including CC [14], CC using GA and DE [17], ACC [18], and ASW [21]. In CC techniques, two CCs have been used on either side of data subcarriers, while in the SW technique all subcarriers are taken into consideration.…”

“…The comparison of the proposed technique is done with the existing techniques. i.e., CC [14], CC using GA and DE [17], ACC [18], and ASW [21]. Two CCs have been taken on both sides of the data subcarriers in all cancellation carrier techniques.…”

“…In [17] the weights of cancellation carriers are calculated using Genetic Algorithm (GA) and Differential Evolution (DE). In [18] Selim, A., et al propose a heuristic algorithm for calculating the weighting factors for the CCs with few computations. Active and null cancellation carriers (ANCC) [19] technique combine active and null cancellation carriers in the guard band.…”