Yue Kai Huang

Terabit Optical Access Networks Based on WDM-OFDMA-PON

Next-generation optical access networks are envisioned to evolve into a converged, high-speed, multiservice platform supporting residential, business, mobile backhaul, and special purpose applications. Moreover, bandwidth demand projections suggest that terabit aggregate capacity may need to be reached in such next-generation passive optical networks (PON). To satisfy these requirements while leveraging the large investments made in existing fiber plants, a wavelength division multiplexed (WDM)-based long-reach PON architecture combined with a multiple access technology that features a passive last-mile split, large per-λ speeds, and statistical bandwidth multiplexing can be exploited. In this paper, the first terabit PON based on hybrid WDM orthogonal frequency division multiple access (OFDMA) technology is proposed and experimentally verified. To enable high-speed, long-reach transmission with simplified optical network unit (ONU)-side digital signal processing, multiband OFDMA with ONU-side sub-band selectivity is proposed. Design challenges and tradeoffs between analog and digital domain sub-band combining and selection are also discussed. Finally, the experimental setup and results of the first 1.2 Tb/s (1 Tb/s after overhead) symmetric WDM-OFDMA-PON over 90 km straight single-mode fiber and 1:32 passive split, featuring multiband OFDMA, digitally selective ONUs, and a coherent-receiver OLT are presented and analyzed. By supporting up to 800 ONUs with 1.25/10 Gb/s guaranteed/peak rates and exhibiting a record rate-distance product achieved in long-reach PON, the demonstrated architecture may be viewed as promising for future converged terabit optical metro/access.

Experimental demonstration and scalability analysis of a four-node 102-Gchip/s fast frequency-hopping time-spreading optical CDMA network

We present experimental and simulation results from a 102-Gchips/s incoherent wavelength-hopping time-spreading optical code-division multiple-access testbed, utilizing four 50-GHz ITU grid wavelengths. Error-free operation of four users is obtained with an effective power penalty /spl sim/0.5 dB. Simulation studies show scalability to >10 users with an effective power penalty of /spl sim/4 dB. The simulation study of the impact of asynchronous access on the performance allows for a complete network design from an engineering viewpoint.

Terabit/s Nyquist Superchannels in High Capacity Fiber Field Trials Using DP-16QAM and DP-8QAM Modulation Formats

We report the results of two field trials aimed at achieving high fiber capacity over regional and long-haul distances. In the first trial, 41 superchannels with digital Nyquist pulse-shaping were generated and tightly packed to fill up both C-band and L-band. Each subcarrier was modulated with 24.8-Gbaud dual-polarization 16 quadrature amplitude modulation (DP-16QAM) data. The signal carrying net 54.2 Tb/s data was transmitted over 634 km of dispersion uncompensated field-installed standard single mode fiber with the aid of hybrid EDFA and Raman amplification and digital coherent detection. In the second trial for long-haul distances, we extended the transmission distance over 1,822 km. This increase in reach was achieved by reducing the net total capacity to 40.5 Tb/s and modulating the signals with dual-polarization 8 quadrature amplitude modulation (DP-8QAM) Nyquist carrier modulation. A novel rate-adaptive low-density parity-check coding was employed, so that the transmitted channels can exhibit different code rates, adapted by the concatenation of hard-decision and soft-decision forward error correcting codes for enhancing error-correction capability. To the best of our knowledge, we achieved the highest field trial capacity to date at 54.2 Tb/s in regional distances. Furthermore, in long-haul applications, the reported capacity × distance product of 73.79 Pb/s·km is the highest to date.

1.92Tb/s coherent DWDM-OFDMA-PON with no high-speed ONU-side electronics over 100km SSMF and 1:64 passive split

Record 1.92-Tb/s (40λ × 48 Gb/s/λ) coherent DWDM-OFDMA-PON without high-speed ONU-side ADCs/DACs/DSP/RF clock sources is demonstrated over 100 km straight SSMF with a 1:64 passive split. Novel optical-domain OFDMA sub-band selection, coherent detection, and simple RF components are exploited. As the first experimental verification of a next-generation optical platform capable of delivering 1 Gb/s to 1000(+) users over 100 km, the new architecture is promising for future optical access/metro systems.

Simultaneous all-optical 3R regeneration scheme with improved scalability using TOAD

A novel re-timing, re-amplifying, and re-shaping (3R) regeneration system is proposed to process multiple WDM (wavelengthdivision-multiplexing) channels simultaneously. Its re-timing capability is investigated by both simulation and experiment with polarizationscrambling method at 10 Gb/s bit rate. Jitter tolerance up to 0.8 UIpp is demonstrated with BER improvement and floor breaking ability.

Novel Optical Access and Digital Processing Architectures for Future Mobile Backhaul

In this paper, primary technical challenges for emerging optical mobile backhaul (MBH) networks are discussed, with a focus on novel optical access and digital signal processing (DSP) architectures for future MBH. The first downstream/upstream Orthogonal Frequency Division Multiple Access and Time Division Multiple Access Passive Optical Network (OFDMA/TDMA-PON) achieving >;100 Mb/s per-cell mobile backhaul and burst-mode operation using off-the-shelf avalanche photodiodes (APDs) is proposed and experimentally demonstrated for last-mile optical MBH with 200 cells per fiber. In the new approach, the use of OFDMA is motivated by the capability to establish low latency, virtual point-to-point links in the frequency-domain to serve high-density cell areas, while a judicious hybrid of DSP-enhanced digital radio-over-fiber (dRoF) and TDMA is proposed as an efficient way to meet <; 1 ms latency constraints subject to a 3 dB upstream burst-mode dynamic range tolerance. By thus enabling high speed, low latency, and low cost via simplified optics, the novel OFDMA/TDMA-PON is promising for future 4G and beyond optical backhaul networks.

Coherent 40Gb/s OFDMA-PON for long-reach (100 + km) high-split ratio (>1:64) optical access/metro networks

We experimentally demonstrate the first coherent 40Gb/s OFDMA-PON over 100km and 130km straight SSMF with 1:128 and 1:64 passive splits, respectively. By satisfying heterogeneous reach/split requirements, the approach addresses key aspects of optical access/metro convergence.

30Tb/s C- and L-bands bidirectional transmission over 10,181km with 121km span length

We demonstrated the first 30Tb/s (350 × 85.74Gb/s) optical transmission over 10,181km using bidirectional C/L-bands, 121.2km hybrid fiber spans, DP-QPSK modulation and EDFAs. Achieved 306Petabit/s•km capacity × distance product is the highest reported to date for WDM transmission.

4 + G mobile backhaul over OFDMA/TDMA-PON to 200 cell sites per fiber with 10Gb/s upstream burst-mode operation enabling < 1ms transmission latency

The first downstream/upstream OFDMA/TDMA-PON achieving >;100Mb/s per-cell mobile backhaul and burst-mode operation using off-the-shelf APDs is demonstrated over 1.645km for 200 cells. The new approach enables <;1ms transmission latency and 3dB burst-mode dynamic range tolerance.

Experimental demonstration and scalability analysis of a 4-node 102 Gchip/s fast frequency-hopping time-spreading optical CDMA network

This study demonstrates a 4-node OCDMA network testbed at 102 Gchip/s and studies its scalability to 10 simultaneous users. The results show small performance degradation with increased network size (/spl sim/ 0.5 dB) and /spl sim/ 4 dB for four and ten users respectively) and demonstrate the viability of OCDMA as a solution for high-speed, asynchronous optical access networks.