Milorad Cvijetic

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.

Integrating optical and wireless services in the access network

Optical fiber technology is a fundamental solution for broadband access and metropolitan networking, and worldwide interoperability for microwave access (WiMAX) is the promising wireless counterpart. Combining the benefits of optical fiber capacity and wireless mobility, we propose several optical wireless integration scenarios in the access network. The integrated network performance has been evaluated through simulations in the OPNET modeler. The results demonstrate that optical wireless integration increases the capacity of wireless networks, promotes mobility in access networks, and decreases access point complexity through centralized management at the edge node.

10-Gb/s OFDMA-PON for Delivery of Heterogeneous Services

We propose a novel method to generate transparent pipes for transmission of heterogeneous services over 10-Gb/s OFDMA-PON architecture. We successfully demonstrated the simultaneous transmission of two PON channels combined with a standard WiMAX channel.

Using LDPC-Coded Modulation and Coherent Detection for Ultra Highspeed Optical Transmission

We propose the coded modulation schemes for ultrahigh-speed transmission (100 Gb/s and above) by using commercially available components operating at 40 gigasymbols/s. The bit-interleaved coded modulation in combination with the low-density parity-check codes that are used as component codes has been applied. The modulation is based on either M-ary quadrature-amplitude modulation or M-ary phase-shift keying. bits are mapped into the corresponding signal constellation point using either Gray or natural mapping. The coherent detection scheme has been found to outperform the direct detection one and to provide an additional margin much needed for longer transmission distances or for application in an all-optical network scenario.

Dynamic multidimensional optical networking based on spatial and spectral processing

The recent introduction of optical OFDM and spatial MIMO techniques has led to considerable increases in spectral efficiency and aggregate throughput for future optical networks. However, these spatial and spectral domains can also be exploited for next-generation elastic optical networking. In this paper, we introduce the first hierarchy for dynamic multidimensional spatial and spectral optical networking and complement it with adaptive coded-modulation to form the basis of a novel elastic networking concept.

Transmission of 32-Tb/s Capacity Over 580 km Using RZ-Shaped PDM-8QAM Modulation Format and Cascaded Multimodulus Blind Equalization Algorithm

In this paper, we propose a novel synthesizing method for high-speed 8-ary quadratic-amplitude modulation (QAM) optical signal generation using commercial optical modulators with binary electrical driving signals. Using this method, we successfully generated 114-Gb/s pulse-duration modulation (PDM)-8QAM optical signals. Intradyne detection of PDM-8QAM optical signals with robust blind polarization demultiplexing has been demonstrated by using a new cascaded multimodulus equalization algorithm. With return-to-zero-shaped PDM-8QAM modulation and the proposed blind polarization demultiplexing algorithm, we demonstrate transmission of a record 32-Tb/s fiber capacity (320 × 114 Gb/s) over 580 km of ultralow-loss single-mode fiber-28 fiber by utilizing C+L-band erbium-doped fiber-amplifier-only optical amplification and single-ended coherent detection technique at an information spectral efficiency of 4.0 bit/s·Hz.

17 Tb/s (161×114 Gb/s) PolMux-RZ-8PSK transmission over 662 km of ultra-low loss fiber using C-band EDFA amplification and digital coherent detection

Employing PolMux-RZ-8PSK modulation and coherent detection, we demonstrate 25 GHz-spaced, 161times114 Gb/s DWDM transmission through eight spans of ultra-low-loss fiber (average span length/loss of 82.75 km/14.6 dB) with a record capacity of 17 Tb/s (spectral efficiency 4.2 b/s/Hz) within the C-band EDFA bandwidth (4.025 THz).

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.

QoS-Aware Scheduling over Hybrid Optical Wireless Networks

Hybrid optical wireless networks present the future-proof solution to the currently deployed copper access infrastructure. Purposing to increase the network throughput under the hybrid framework, we propose a scheduling scheme to deliver diverse services by taking the quality of service (QoS) requirement into consideration. Simulation results demonstrate that our scheme is capable of collecting the QoS requirement information throughout the network, and the centralized process facilitates the reduction of network transmission overhead.

Proposal for Beyond 100-Gb/s Optical Transmission Based on Bit-Interleaved LDPC-Coded Modulation

An iterative bandwidth-efficient coded modulation scheme based on bit-interleaving low-density parity-check (LDPC) codes, and M-ary differential phase-shift keying is proposed. A bit-interleaved LDPC-coded scheme, carrying 3 bits/symbol, provides the coding gain of 8.3 dB at a bit-error rate (BER) of 10-7. The expected coding gain at BER of 10-12 is 12.8 dB. Possible applications include 100G Ethernet, and high-speed (>100 Gb/s) long-haul transmission