On the Performance of Cancellation Carrier-Based Schemes for Sidelobe Suppression in OFDM Networks

An efficient scheme for limiting the inherent high out-of-band radiation of the orthogonal frequency-division multiplexing signal has been studied by Brandes et al.. The scheme achieves sidelobe suppression by using few subcarriers, referred to as cancellation carriers (CCs), positioned at the edges of the spectrum and modulated by data-dependent complex-valued symbols that are designed so as to minimize the out-of-band radiation. Unfortunately, its performance has been investigated at the input of the power amplifier (PA) without considering the spectral re-growth induced by PA's non-linear region. Motivated by the above consideration, in this work we return to the aforementioned scheme and investigate its performance at the output of the PA. In addition, since reducing the time-domain signal peaks may alleviate the problem of spectral re-growth, we also adopt two well-known tone reservation (TR)-based peak reduction algorithms. Computer simulations are used to assess the performance of the investigated schemes under different operating conditions. It turns out that the CC-based solution may provide some performance gain at the PA output only for input power backoffs larger than 6 dB. Additional benefits can be achieved when used in conjunction with TR and some linearization of the PA characteristic.