PAPR-Degraded Secure OFDM-WDM-PON Based on Chaotic Set-Partitioned SLM

This letter proposes and experimentally demonstrates an orthogonal frequency division multiplexing wavelength division multiplexing passive optical network (OFDM-WDM-PON) system based on novel chaotic set-partitioned selective mapping (SP-SLM) scheme. With the implementation of a three-dimensional chaotic system, peak-to-average power ratio (PAPR) reduction and chaotic encryption are simultaneously realized on the process of OFDM signal modulation, so as to enhance the system performance in the presence of PAPR, bit error rate (BER), fiber nonlinear tolerance and security. The experimental results show that, when compared with original OFDM signal, the OFDM signal with SP-SLM can achieve 4 dB PAPR reduction at the complementary cumulative distribution function value of $10^{-4}$ , as well as a 1.1 dB gain in receiver sensitivity at a BER of $10^{-3}$ . For fiber nonlinear tolerance, the optimal launch fiber power of OFDM signal with SP-SLM is 10 dBm, which is better than 9 dBm of original OFDM signal under the same received optical power of −16 dBm. Furthermore, the key space of the proposed scheme can reach up to $10^{98}$ , which is large enough to effectively protect against illegal attackers.

I. Introduction

Considered as a future-oriented solution, wavelength division multiplexing passive optical network (WDM-PON) is capable of coping with the rapidly increasing requirement for bandwidth and capacity in next-generation optical access networks [1], [2]. Orthogonal frequency division multiplexing (OFDM) WDM-PON with intensity modulation/direct detection (IM/DD) has been borne out to be a cost-effective technique to improve spectral efficiency and fiber dispersion tolerance. Unfortunately, OFDM technology is of high peak-to-average power ratio (PAPR) [3]. The fact poses a problem that system’s components need to have a large linear operating range. Numerous effective methods for PAPR reduction have been proposed such as selective mapping (SLM) [4], partial transmission sequence (PTS) [5], clipping and filtering (CF) [6], tone reservation (TR) [7], and tone injection (TI) [8]. Despite the remarkable advantage of no additional sideband demand for the simple CF scheme, it leads to a problem of system BER performance degradation due to OFDM signal distortion. The TR and TI require more time to find the OFDM signal with the best PAPR performance, posing a challenge of extremely high computational complexity. The SLM and PTS have the impressive advantage of improving system BER performance by abating PAPR effectively. The costs, however, are low spectral efficiency and high computational complexity.