Reginaldo B. Nunes

Transmission of CE-OFDM Signals Over MMF Links Using Directly Modulated 850-nm VCSELs

We report the experimental transmission of constant-envelope orthogonal frequency division multiplexing (CE-OFDM) signals over short-reach multimode fiber links. Error-free transmission of 2.2 Gb/s over a 300-m OM-3 fiber link, using a directly modulated 850-nm vertical-cavity surface emitting laser and direct detection, is achieved. The results confirm the CE-OFDM modulation format as a low peak-to-average power ratio alternative for low-cost data-center interconnects.

Impact of Optical Power in the Guard-Band Reduction of an Optimized DDO-OFDM System

A multiobjective optimization on the parameters of direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems in short-range links is proposed. Based on genetic algorithms, the optimization process takes into account the influence of optical power in the guard-band reduction of such multicarrier systems with 4and 16-quadratic-amplitude modulation (QAM) subcarrier mapping and for propagation in 40 km of standard single-mode fiber (SSMF). Simulation results show that the parameters optimization is responsible for a gain of approximately 2.5 dB [≈ 1.8 dB] in the required optical power for bit-errorrate ≤10-3, for DDO-OFDM system transmission over 40 km of uncompensated SSMF, with a guard band BG equals to 50% of the signal bandwidth Bw and 16-QAM [4-QAM] subcarrier mapping. For an extremely reduced guard band of only 1% of Bw, the gain reduced to ≈ 0.5 dB and ≈ 1.5 dB for 16and 4-QAM mapping, respectively. The optimization process is experimentally validated under the transmission of the optimized DDO-OFDM systems in optical back-to-back (B2B) configuration and 40 km of uncompensated SSMF. A fair performance comparison is discussed in the experimental results considering BG/Bw = 0.5 and BG/Bw = 0.01 in the range of the optimized optical powers. It is shown that a maximum optical power penalty of approximately 2 dBm is registered according to a guard-band reduction from 50% to 1% of the useful bandwidth, for transmission over the 40 km of SSMF, considering 16-QAM subcarrier mapping.

Experimental Demonstration of a 33.5-Gb/s OFDM-Based PON With Subcarrier Pre-Emphasis

Spectral efficiency is one of the critical issues in passive optical networks (PONs). Thus, next generation PON systems must employ advanced modulation techniques and channel compensation to improve the network performance and provide more bandwidth for end users. In this letter, we have experimentally demonstrated a spectral efficiency improvement in PONs based on the bandwidth scalable orthogonal frequency division multiplexing (BSOFDM-PON), considerably reducing the recommended optical guard band of such direct detection systems. The experimental results show that this efficiency can be achieved in a 33.5-Gb/s BSOFDM-PON on one wavelength channel when subcarrier pre-emphasis is used.

High spectral efficient and flexible multicarrier D-RoF modem using up to 1024-QAM modulation format

We propose a flexible optical SCM modem to transmit, with high spectral efficiency, mobile front-haul signals. The real time experimental results, demonstrate the multicarrier aggregation capacity of 3.6 Gbps based on four 1024-QAM D-RoF subcarriers and a 30km transmission reach.

Evaluation of selective control information detection scheme in orthogonal frequency division multiplexing-based radio-over-fiber and visible light communication links

Abstract. Block-level detection is required to decode what may be classified as selective control information (SCI) such as control format indicator in 4G-long-term evolution systems. Using optical orthogonal frequency division multiplexing over radio-over-fiber (RoF) links, we report the experimental evaluation of an SCI detection scheme based on a time-domain correlation (TDC) technique in comparison with the conventional maximum likelihood (ML) approach. When compared with the ML method, it is shown that the TDC method improves detection performance over both 20 and 40 km of standard single mode fiber (SSMF) links. We also report a performance analysis of the TDC scheme in noisy visible light communication channel models after propagation through 40 km of SSMF. Experimental and simulation results confirm that the TDC method is attractive for practical orthogonal frequency division multiplexing-based RoF and fiber-wireless systems. Unlike the ML method, another key benefit of the TDC is that it requires no channel estimation.

A MAC layer protocol for a bandwidth scalable OFDMA PON architecture

A medium access control (MAC) layer protocol for passive optical networks (PONs) based on orthogonal frequency division multiple access (OFDMA) is proposed in this paper. The protocol is able to exploit statistical multiplexing to offer an efficient bandwidth control with greater flexibility and granularity to the bandwidth allocation, hence, providing high performance measured in terms of throughput, delay and jitter. The main recommendations of the proposed MAC are described in accordance to the physical layer features of the architecture named Bandwidth Scalable OFDMA PON (BS-OFDMA PON). Simulation results show that the proposed architecture based on tree topology is able to provide triple-play services to 32 optical network units (ONUs) and transmission rates above 33Gb/s per wavelength.

Reducing the guard-band of a DDO-OFDM system by Multi-objective optimization

A Multi-objective optimization on the parameters of direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems in short-range links is proposed. Based on Genetic Algorithms (GA), the optimization process takes into account the influence of optical power in the guard-band reduction of such multicarrier systems with 4 and 16-QAM subcarrier mapping and for propagation in 40 km of standard single-mode fiber (SSMF). Simulation results show that the parameters optimization is responsible for a gain of ≈ 2.5 dB [≈ 1.8 dB] in the required optical power for a bit-error-rate of 10-3, for DDO-OFDM system transmission over 40 km of uncompensated SSMF, with a guard band (BG) equals to 50% of the signal bandwidth (Bw) and 16-QAM [4-QAM] subcarrier mapping. For a extremely reduced guard-band of only 1% of Bw, the gain reduced to ≈ 0.5 dB and ≈ 1.5 dB for 16-QAM and 4-QAM mapping, respectively.

Transmission of CE-OFDM Signals over 300 m of MMF Using VCSEL

We report an experimental transmission of CE-OFDM signals over 300 m of MMF links. The results of the peak-to-average power ratio reduction technique prove its application in MMF links using VCSEL.

Performance Optimization of DDO-OFDM Systems through Genetic Algorithms

The employment of genetic algorithms in parameters optimization of direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems in short-range links is reported. Experimental transmission of a 3.56 Gb/s (4-QAM subcarrier mapping) optimized DDO-OFDM system in optical back-to-back (B2B) configuration and through 20 and 40 km of uncompensated standard single-mode fiber (SSMF) was achieved.