Orthogonal Frequency Division Multiplexing Passive Optical Network Research Articles

Constellation-masked secure communication technique for OFDM-PON

This paper proposes a novel secure communication technique using constellation masking for applications in orthogonal frequency division multiplexing passive optical network (OFDM-PON). The constellation masking is applied both on each subcarrier and among different subcarriers. The Arnold mapping is utilized as the parameter function for the mask factors. A interleave length is employed to provide a scalable masking granularity for different ONUs. A 15.54 Gb/s constellation-masked 32QAM-OFDM signal has been successfully transmitted over 25-km single mode fiber in the experiment. Experimental results show that the proposed scheme can effectively protect the system from illegal ONU without wasting the bandwidth. The constellation-masked technique suggests an effective solution for the physical secure communication in future OFDM access network.

A High-Performance OFDMA PON System Architecture and Medium Access Control

Orthogonal frequency-division multiplexing (OFDM) passive optical network (PON) has been considered to be a promising next-generation broadband wired access solution. However, based on the current tree-based architecture, existing OFDM PON systems face severe challenges when increasing the scalability and data-rate performance. In this paper, we propose a high-performance virtual-tree orthogonal frequency-division multiple access PON system (VTOPS). With the virtual-tree architecture and coupled with the use of inexpensive direct modulation, VTOPS features high reliability, scalability, spectrum efficiency, and cost effectiveness all at once. For governing the flexible/fair access and dynamic allocation of bandwidth, VTOPS incorporates a rate-based medium access control (MAC) scheme. The MAC scheme performs dynamic rate adjustment using a neural-fuzzy system. By adjusting the system parameters, the MAC scheme can achieve a wide range of delay and fairness performance under a variety of traffic patterns. Finally, we show both theoretical and experimental results to demonstrate that, by applying the power pre-emphasis algorithm and adaptive subchannel modulation, VTOPS achieves 40 Gb/s downlink and 40 Gb/s uplink transmissions, using low-cost 10 GHz directly modulated lasers.

Frequency Response Equalization of Optical Transceivers Enabling OEO-Based Extender in OFDM-PON Systems

We investigate the feasibility of using a 1R optical-electrical-optical-based extender in orthogonal frequency-division multiplexing passive optical network (OFDM-PON) systems; our key advance is an equalization algorithm composed of a fractionally spaced equalizer and self-phase error correction in conjunction with a one-tap equalizer. The proposed algorithm maximizes the available system bandwidth, which would otherwise suffer the unavoidable limitations created by the cascaded components used in the actual transceivers of OFDM-PON systems.

Physical-enhanced secure strategy in an OFDM-PON

The physical layer of optical access network is vulnerable to various attacks. As the dramatic increase of users and network capacity, the issue of physical-layer security becomes more and more important. This paper proposes a physical-enhanced secure strategy for orthogonal frequency division multiplexing passive optical network (OFDM-PON) by employing frequency domain chaos scrambling. The Logistic map is adopted for the chaos mapping. The chaos scrambling strategy can dynamically allocate the scrambling matrices for different OFDM frames according to the initial condition, which enhance the confidentiality of the physical layer. A mathematical model of this secure system is derived firstly, which achieves a secure transmission at physical layer in OFDM-PON. The results from experimental implementation using Logistic mapped chaos scrambling are also given to further demonstrate the efficiency of this secure strategy. An 10.125 Gb/s 64QAM-OFDM data with Logistic mapped chaos scrambling are successfully transmitted over 25-km single mode fiber (SMF), and the experimental results show that proposed security scheme can protect the system from eavesdropper and attacker, while keep a good performance for the legal ONU.

A 40-Gb/s OFDM PON System Based on 10-GHz EAM and 10-GHz Direct-Detection PIN

This letter demonstrates a 40-Gb/s optical double-sideband (ODSB) orthogonal frequency-division multiplexing passive optical network (OFDM-PON) system using a cost-effective 10-GHz-bandwidth electroabsorption modulator (EAM). By employing a subcarrier-adaptive modulation format and pre-emphasis, we successfully achieve 20-km EAM-based single-mode-fiber (SMF) transmission.

Optical MIMO transmission for SCFDM-PON based on polarization interleaving

Orthogonal frequency division multiplexing-passive optical network (OFDM-PON) and single-carrier frequency division multiplexing (SCFDM)-PON are promising solutions for future high-speed PON-based access. A polarization division multiplexing scheme with direct detection is proposed for OFDM-PON to effectively reduce bandwidth requirements for components. However, the scheme strictly requires spectrum overlapping of two orthogonal sidebands and the 4×4 multi-input-multi-output (MIMO) algorithm to eliminate complex cross-polarization interference. In this letter, we propose a polarization interleaving (PI) approach that significantly reduces bandwidth requirements for optical and electrical components while achieving a high-flexibility and low-complexity MIMO algorithm. Downstream single sideband PI-SCFDM transmission is experimentally demonstrated.

Secure OFDM-PON Based on Chaos Scrambling

This letter proposes and experimentally demonstrates a secure orthogonal frequency-division-multiplexing passive optical network (OFDM-PON) based on the chaos scrambling in the OFDM frequency domain. The Logistic map is adopted for the chaos mapping. The chaos scrambling algorithm can dynamically allocate the scrambling matrices for different OFDM frames according to the initial condition, which enhance the confidentiality of the physical layer. It achieves a secure transmission at physical layer in OFDM-PON for data encryption. The experiment successfully transmits 8.37-Gb/s OFDM data with Logistic mapped chaos scrambling over 25-km single-mode fiber (SMF), and the results indicate the robustness against eavesdropping.

Studies of OFDM signal for broadband optical access networks

Using orthogonal-frequency-division-multiplexing (OFDM) format for passive optical network (PON) is a subject of great interest for recent research works. OFDM signal has high spectral efficiency, high tolerance to the fiber chromatic dispersion and the high flexibility on both multiple services provisioning and dynamic bandwidth allocation. In this paper we study the use of OFDM signals for optical access networks, including carrier distributed PON, heterogeneous optical wired/wireless network and a 100 Gb/s OFDM-PON. We first quantify the performance of the OFDM signal when subjected to the noise produced by two different Rayleigh backscattering (RB) components that are present in the carrier-distributed PON. Then, based on these results, we also study the possibility of using OFDM for signal remodulation in a long-reach (LR)-PON. We propose carrier-distributed OFDM PONs using a dual-feeder fiber architecture and wavelength-shifting to mitigate the RB noise. Afterwards, we propose heterogeneous optical wired/wireless access networks, combining 10 Gb/s PON and 10 Gb/s OFDM radio-over-fiber (ROF) network. Finally, we propose a 100 Gb/s OFDM-PON using subcarrier multiplexing (SCM).