Ross Saunders

Polarization-multiplexed rate-adaptive non-binary-quasi-cyclic-LDPC-coded multilevel modulation with coherent detection for optical transport networks.

In order to achieve high-speed transmission over optical transport networks (OTNs) and maximize its throughput, we propose using a rate-adaptive polarization-multiplexed coded multilevel modulation with coherent detection based on component non-binary quasi-cyclic (QC) LDPC codes. Compared to prior-art bit-interleaved LDPC-coded modulation (BI-LDPC-CM) scheme, the proposed non-binary LDPC-coded modulation (NB-LDPC-CM) scheme not only reduces latency due to symbol- instead of bit-level processing but also provides either impressive reduction in computational complexity or striking improvements in coding gain depending on the constellation size. As the paper presents, compared to its prior-art binary counterpart, the proposed NB-LDPC-CM scheme addresses the needs of future OTNs, which are achieving the target BER performance and providing maximum possible throughput both over the entire lifetime of the OTN, better.

Real-Time Single-Carrier Coherent 100 Gb/s PM-QPSK Field Trial

The development of 100 Gb/s transponder technology is progressing rapidly to meet the needs of next-generation optical/IP carrier networks. In this paper, we describe the upgrade of an installed 10 Gb/s field system to 100 Gb/s using a real-time single-carrier, coherent 100 Gb/s polarization-multiplexed quadrature-phase-shift keyed channel. Performance sufficient for error-free operation after forward-error-correction was achieved over installed 900 and 1800 km links, proving the viability of 100 Gb/s upgrades to most installed systems. Excellent tolerance to fiber polarization mode dispersion and narrowband optical filtering demonstrates the applicability of this technology over the majority of installed fiber plant and through existing 50 GHz reconfigurable optical add/drop multiplexers.

High-Rate Nonbinary Regular Quasi-Cyclic LDPC Codes for Optical Communications

The parity-check matrix of a nonbinary (NB) low-density parity-check (LDPC) code over Galois field GF(q) is constructed by assigning nonzero elements from GF(q) to the 1s in corresponding binary LDPC code. In this paper, we state and prove a theorem that establishes a necessary and sufficient condition that an NB matrix over GF(q), constructed by assigning nonzero elements from GF(q) to the 1s in the parity-check matrix of a binary quasi-cyclic (QC) LDPC code, must satisfy in order for its null-space to define a nonbinary QC-LDPC (NB-QC-LDPC) code. We also provide a general scheme for constructing NB-QC-LDPC codes along with some other code construction schemes targeting different goals, e.g., a scheme that can be used to construct codes for which the fast-Fourier-transform-based decoding algorithm does not contain any intermediary permutation blocks between bit node processing and check node processing steps. Via Monte Carlo simulations, we demonstrate that NB-QC-LDPC codes can achieve a net effective coding gain of 10.8 dB at an output bit error rate of 10-12. Due to their structural properties that can be exploited during encoding/decoding and impressive error rate performance, NB-QC-LDPC codes are strong candidates for application in optical communications.

Nonbinary Quasi-Cyclic LDPC-Based Coded Modulation for Beyond 100-Gb/s Transmission

We propose using coded modulation based on nonbinary quasi-cyclic low-density parity-check (LDPC) codes for beyond 100-Gb/s optical transmission. The proposed scheme not only lowers the latency in the system but also offers much higher coding gains than its binary counterpart based on bit-interleaved coded modulation (BICM). We show that using component LDPC codes over high order finite fields and matching bandwidth-efficient modulations, our scheme can provide around 1-dB coding gain improvement at the bit-error ratio of 10-6 compared to a corresponding BICM-based scheme.

Coherent 100 Gb/s PM-QPSK field trial

The development of 100 Gb/s transponder technology is progressing rapidly to meet the needs of next-generation optical/IP carrier networks. In this paper, we describe the upgrade of an installed 10 Gb/s field system to 100 Gb/s using a real-time single-carrier, coherent 100 Gb/s polarization-multiplexed quadrature-phase-shift keyed channel. Performance sufficient for error-free operation after forward-error-correction was achieved over installed 900 and 1800 km links, proving the viability of 100 Gb/s upgrades to most installed systems. Excellent tolerance to fiber polarization mode dispersion and narrowband optical filtering demonstrates the applicability of this technology over the majority of installed fiber plant and through existing 50 GHz reconfigurable optical add/drop multiplexers.

Advances in SiGe ICs for 40 Gb/s signal equalization

IC technologies and major equalizer structures were discussed for designing a 40 Gb/s equalizer chip. Insights, suggestions or comments were given on designing all building blocks for an equalizer circuit, design methodology, and packaging the die.

Rate-adaptive non-binary-LDPC-coded polarization-multiplexed multilevel modulation with coherent detection for optically-routed networks

Adaptation to changing conditions in the transmission medium is a particularly desired property in optically-routed networks due to their heterogeneous nature. Toward this goal, we propose in this paper rate-adaptive polarization multiplexed coded multilevel modulation schemes based on non-binary quasi-cyclic low-density parity-check (LDPC) codes and coherent detection. The proposed scheme can support data rates at 100 Gb/s and beyond while offering comparably better forward error correction performance with less computational complexity than bit-interleaved coded modulation schemes. The ability to adapt changing channel conditions is achieved by exploiting the inherent structure of quasi-cyclic LDPC codes.

Transmission of 40 Gbps signals through metropolitan networks engineered for 10 Gbps signals

A critical emerging technology for advanced DWDM systems is 40 Gbps transmission support. The use of 40 Gbps channels increases the DWDM capacity by the factor of four, supports interconnection of next generation IP routers at OC-768 and saves OpEx and CapEx due to having to deploy and maintain fewer channels to provide the same capacity, needing fewer spare transponder modules. A key design driver for 40 Gbps technology is that it should seamlessly integrate with existing 10 Gbps systems without requiring changes to the common equipment, including ROADM technology. Parameters that must be analyzed to a greater degree at the 40 Gbps transmission rate include chromatic dispersion, PMD, and filtering effects. This analysis is based on the experiment on deployment of 43 Gb/s PSBT signals over an existing 10 Gb/s DWDM system with cascaded ROADMs that we reported on last year (M. Boduch et al., 2005).

Economics of 100Gb/s transport

Deploying spectrally-efficient 100 Gb/s coherent transponder technology in carrier networks can yield substantial CAPEX and OPEX savings. This paper discusses these economic gains and how a carrier can maximize their return on optical transport investment.

Non-binary quasi-cyclic LDPC-coded modulation for beyond 100 Gb/s optical transmission

For optical transmission at 100Gb/s and beyond, we propose using coded modulation based on non-binary quasicyclic LDPC codes. We show that the proposed schemes offer better performance than their counterparts based on bitinterleaved LDPC-coded modulation.