Showing papers on "Polarization mode dispersion published in 2009"

DSP for Coherent Single-Carrier Receivers

Abstract: In this paper, we outline the design of signal processing (DSP) algorithms with blind estimation for 100-G coherent optical polarization-diversity receivers in single-carrier systems. As main degrading optical propagation effects, we considered chromatic dispersion (CD), polarization-mode dispersion (PMD), polarization-dependent loss (PDL), and cross-phase modulation (XPM). In the context of this work, we developed algorithms to increase the robustness of the single DSP receiver modules against the aforesaid propagation effects. In particular, we first present a new and fast algorithm to perform blind adaptive CD compensation through frequency-domain equalization. This low complexity equalizer component inherits a highly precise estimation of residual dispersion independent from previous or subsequent blocks. Next, we introduce an original dispersion-tolerant timing recovery and illustrate the derivation of blind polarization demultiplexing, capable to operate also in condition of high PDL. At last, we propose an XPM-mitigating carrier phase recovery as an extension of the standard Viterbi-Viterbi algorithm.

Principal Modes in Graded-Index Multimode Fiber in Presence of Spatial- and Polarization-Mode Coupling

Abstract: Power-coupling models are inherently unable to describe certain mode coupling effects in multimode fiber (MMF) when using coherent sources at high bit rates, such as polarization dependence of the impulse response. We develop a field-coupling model for propagation in graded-index MMF, analogous to the principal-states model for polarization-mode dispersion in single-mode fiber. Our model allows computation of the fiber impulse response, given a launched electric-field profile and polarization. In order to model both spatial- and polarization-mode coupling, we divide a MMF into numerous short sections, each having random curvature and random angular orientation. The model can be described using only a few parameters, including fiber length, number of sections, and curvature variance. For each random realization of a MMF, we compute a propagation matrix, the principal modes (PMs), and corresponding group delays (GDs). When the curvature variance and fiber length are small (low-coupling regime), the GDs are close to their uncoupled values, and scale linearly with fiber length, while the PMs remain highly polarized. In this regime, our model reproduces the polarization dependence of the impulse response that is observed in silica MMF. When the curvature variance and fiber length are sufficiently large (high-coupling regime), the GD spread is reduced, and the GDs scale with the square root of the fiber length, while the PMs become depolarized. In this regime, our model is consistent with the reduced GD spread observed in plastic MMF.

Optical Performance Monitoring in Digital Coherent Receivers

Abstract: In this paper, we present a method for combined fiber parameter estimation from digital filter coefficients of a polarization diverse coherent receiver. All deterministic linear optical channel parameters like residual chromatic dispersion (CD), polarization-mode dispersion (PMD), and polarization-dependent loss (PDL) are continuously monitored by analysis of the filter impulse response of the adaptive equalizer. After deriving the according equations from the theoretical linear fiber channel model, we demonstrate robust estimation for a joint combination of all impairments.

Optical frequency transfer via 146 km fiber link with 10 -19 relative accuracy.

Abstract: We demonstrate the long-distance transmission of an ultrastable optical frequency derived directly from a state-of-the-art optical frequency standard. Using an active stabilization system we deliver the frequency via a 146-km-long underground fiber link with a fractional instability of 3×10−15 at 1 s, which is close to the theoretical limit for our transfer experiment. After 30,000 s, the relative uncertainty for the transfer is at the level of 1×10−19. Tests with a very short fiber show that noise in our stabilization system contributes fluctuations that are 2 orders of magnitude lower, namely, 3×10−17 at 1 s, reaching 10−20 after 4000 s.

Theoretical and Experimental Investigations of Direct-Detected RF-Tone-Assisted Optical OFDM Systems

Abstract: In this paper, we propose and experimentally demonstrate a radio frequency (RF)-tone-assisted optical orthogonal frequency-division multiplexing (OFDM) transmission. By inserting an RF tone at the edge of the signal band and biasing the Mach-Zehnder modulator (MZM) at the null point, the proposed system has a better sensitivity and chromatic dispersion (CD) tolerance compared to the previous intensity-modulated single-sideband OFDM (SSB-OFDM). We show analytically that the majority of the linear channel impairments, such as the transmitter, CD, optical filtering, and receiver, can be compensated for by a simple zero-forcing equalizer. Besides, the optimum value of the important parameter, carrier-to-signal-power ratio (CSPR), is analytically obtained and supported via the experimental results. We also observe that the relatively worse sensitivity of the previous SSB-OFDM can be attributed to the limited CSPR. We experimentally demonstrate a 10-Gb/s, 8 quadrature-amplitude modulation (QAM) RF-tone-assisted OFDM transmission, and show that our system has a ~ 5-dB better sensitivity compared to the previous intensity-modulated SSB-OFDM and exhibits a negligible transmission penalty after 260-km uncompensated standard single-mode fiber (SSMF).

Nonlinear Impairment Compensation for Polarization-Division Multiplexed WDM Transmission Using Digital Backward Propagation

Abstract: A comprehensive treatment of digital backward propagation (DBP) accounting for the vectorial nature of optical transmission is presented. Experimental results show that self-phase and cross-phase modulation are the major sources of nonlinear impairments, even for small channel spacings and for transmission in low dispersion fibers. It is verified that compensating only the incoherent nonlinear impairments not only has the advantage of requiring lower computational load but also removes the necessity of using phase-locked carriers for the signal or phase-locked local oscillators. Simulation results show that polarization-mode dispersion has to be taken into account for practical wavelength division multiplexing systems for DBP to work properly. It is found that to compensate interchannel nonlinear impairments, the changes in the polarization states of channels have to be followed at every span.

Robust Multilevel Coherent Optical Systems With Linear Processing at the Receiver

Abstract: This paper investigates optical coherent systems based on polarization multiplexing and high-order modulations such as phase-shift keying (PSK) signals and quadrature amplitude modulations (QAM). It is shown that a simple linear receiver processing is sufficient to perfectly demultiplex the two transmitted streams and to perfectly compensate for group velocity dispersion (GVD) and polarization mode dispersion (PMD). In addition, in the presence of a strong phase noise of the lasers at the transmitter and receiver, a symbol-by-symbol detector with decision feedback is able to considerably improve the receiver robustness with a limited complexity increase. We will also discuss the channel estimation and the receiver adaptivity to time-varying channel conditions as well as the problem of the frequency acquisition and tracking. Finally, a new two-dimensional (polarization/time) differential encoding rule is proposed to overcome a polarization-ambiguity problem. In the numerical results, the receiver performance will be assessed versus the receiver complexity.

Wavelength Multiplexed Optical System with Multimode Optical Fibers

Abstract: The present wavelength multiplexed optical system includes a multimode optical fiber that transmits wavelength multiplexed optical signals and a plurality of multimode modal dispersion compensation optical fibers. Each modal dispersion compensation optical fiber can transmit one of the multiplex wavelengths, and each modal dispersion compensation optical fiber has an optimized index profile such that the modal dispersion for the transmitted wavelength is approximately inversely equal to the modal dispersion induced in the multimode optical fiber. The wavelength multiplexed optical system facilitates an increased bitrate without reducing bandwidth.

Applications of Artificial Neural Networks in Optical Performance Monitoring

Abstract: Applications using artificial neural networks (ANNs) for optical performance monitoring (OPM) are proposed and demonstrated. Simultaneous identification of optical signal-to-noise-ratio (OSNR), chromatic dispersion (CD), and polarization-mode-dispersion (PMD) from eye-diagram parameters is shown via simulation in both 40 Gb/s on-off keying (OOK) and differential phase-shift-keying (DPSK) systems. Experimental verification is performed to simultaneously identify OSNR and CD. We then extend this technique to simultaneously identify accumulated fiber nonlinearity, OSNR, CD, and PMD from eye-diagram and eye-histogram parameters in a 3-channel 40 Gb/s DPSK wavelength-division multiplexing (WDM) system. Furthermore, we propose using this ANN approach to monitor impairment causing changes from a baseline. Simultaneous identification of accumulated fiber nonlinearity, OSNR, CD, and PMD causing changes from a baseline by use of the eye-diagram and eye-histogram parameters is obtained and high correlation coefficients are achieved with various baselines. Finally, the ANNs are also shown for simultaneous identification of in-phase/quadrature (I/Q) data misalignment and data/carver misalignment in return-to-zero differential quadrature phase shift keying (RZ-DQPSK) transmitters.

Local Oscillator Phase Noise Induced Penalties in Optical Coherent Detection Systems Using Electronic Chromatic Dispersion Compensation

Abstract: We show that chromatic dispersion induced local oscillator (LO) phase noise to amplitude noise conversion significantly degrades the performance of a high-speed coherent system without optical dispersion compensation and tightens the requirement on LO linewidth.

Suppression of Fiber Nonlinearities and PMD in Coded-Modulation Schemes With Coherent Detection by Using Turbo Equalization

Abstract: We propose a maximum a posteriori probability (MAP) turbo equalizer based on the sliding-window multilevel Bahl-Cocke-Jelinek-Raviv algorithm. This scheme is suitable for simultaneous nonlinear and linear impairment mitigation in multilevel coded-modulation schemes with coherent detection. The proposed scheme employs large-girth quasicyclic LDPC codes as channel codes. We demonstrate the efficiency of this method in dealing with fiber nonlinearities by performing Monte Carlo simulations. In addition, we provide the experimental results that demonstrate the efficiency of this method in dealing with polarization mode dispersion. We also study the ultimate channel capacity limits, assuming an independent identically distributed source.

Coherent Optical OFDM Transmission Up to 1 Tb/s per Channel

Abstract: Coherent optical frequency-division multiplexing (CO-OFDM) is one of the promising pathways toward future ultrahigh capacity transparent optical networks. In this paper, numerical simulation is carried out to investigate the feasibility of 1 Tb/s per channel CO-OFDM transmission. We find that, for 1 Tb/s CO-OFDM signal, the performance difference between single channel and wavelength division multiplexing (WDM) transmission is small. The maximum Q is 13.8 and 13.2 dB respectively for single channel and WDM transmission. We also investigate the CO-OFDM performance on the upgrade of 10-Gb/s to 100-Gb/s based DWDM systems with 50-GHz channel spacing to 100-Gb/s systems. It is shown that due to the high spectral efficiency and resilience to dispersion, for 100-Gb/s CO-OFDM signals, only 1.3 dB Q penalty is observed for 10 GHz laser frequency detuning. A comparison of CO-OFDM system performance under different data rate of 10.7 Gb/s, 42.8 Gb/s, 107 Gb/s and 1.07 Tb/s with and without the impact of dispersion compensation fiber is also presented. We find that the optimum fiber launch power increases almost linearly with the increase of data rate. 7 dB optimum launch power difference is observed between 107 Gb/s and 1.07 Tb/s CO-OFDM systems.

A Statistical Treatment of Cross-Polarization Modulation in DWDM Systems

Abstract: Starting from a model of random nonlinear polarization rotations for the effect of cross-polarization modulation in DWDM systems, we derive the mean distribution of the time-dependent polarization states at an arbitrary location within an optical link. We show that this distribution is fully parameterized by the degree of polarization of the particular wavelength channel, and we derive expressions to approximate this parameter for general optical links consisting of multiple optically amplified and dispersion-compensated spans, as well as related power thresholds. From the analytical expressions we derive a method to significantly reduce the detrimental effects.

400Gb/s (4 × 100Gb/s) orthogonal PDM-RZ-QPSK DWDM Signal Transmission over 1040km SMF-28

Abstract: We have generated 4 × 100-Gb/s orthogonal WDM optical signal by employing polarization-division-multiplexed (PDM) return-to-zero (RZ) QPSK modulation format and tight optical filtering technique The required optical signal-to-noise ratio (OSNR) at bit error ratio (BER) of 2 × 10−3 for the 400Gb/s orthogonal DWDM signal is measured to be ~228 dB/01nm After transmission over 1040-km standard single mode fiber (EDFA-only amplification, 80-km amplifier span and fully receiver-side electrical dispersion compensation), the measured BER for all the four orthogonal subchannels are smaller than 2 × 10−3

Broadband Dispersion Compensating Octagonal Photonic Crystal Fiber for Optical Communication Applications

Abstract: We numerically report the design of a modified octagonal photonic crystal fiber (M-OPCF) for broadband dispersion compensation covering the C and L communication bands, i.e., wavelengths ranging from 1530 to 1625 nm. It was shown that the proposed broadband compensating PCF can be designed to simultaneously exhibit a high negative dispersion coefficient and a relative dispersion slope (RDS) close to that of a conventional single-mode optical fiber (SMF). From our results, it was found that the M-OPCF has a large negative dispersion [-226 to -290 ps/(nmkm)] over the C- and L-bands, and an RDS close to that of an SMF of about 0.0034 nm-1. In addition to this, the effective dispersion, residual dispersion, confinement loss, and polarization properties of the proposed PCF are also reported and discussed.

Optical OFDM: A promising high-speed optical transport technology

Abstract: Orthogonal frequency division multiplexing (OFDM) is a widely used modulation/multiplexing technology in wireless and data communications. Leveraging recent advances in high-speed complementary metal-oxide semiconductor (CMOS) technologies and optical modulation and detection technologies, optical OFDM at a 40Gb/s or even a 100Gb/s information rate becomes feasible. At the optical transmitter, OFDM is realized by a digital signal processor (DSP) using inverse fast Fourier transformation (iFFT) with subsequent digital-to-analog conversion and Cartesian electro-optic modulation. At the receiver, the signal optical field is first reconstructed, e.g., by coherent detection. Then reverse signal processing is applied to recover the original data. OFDM enables efficient compensation of transmission effects such as chromatic dispersion and polarization mode dispersion that often are prohibiting impairments to cost-effective realization of high-speed optical transport systems. In light of the emerging demand for a 100+ Gb/s data rate in future optical transport systems, optical OFDM is considered to be a promising enabling technology. In this paper, the optical OFDM architectures will be reviewed, and their performance under various system conditions will be discussed and compared with alternative technologies. The challenges in the implementation of optical OFDM will also be discussed.

Adaptive polarization transmission of OFDM signals in channels with polarization mode dispersion and polarization-dependent loss

Abstract: A 2times2 multiple-input multiple-output (MIMO) architecture using dual-polarized antennas (DPAs) is considered with orthogonal frequency division multiplexing (OFDM) The performance of DPAs is evaluated for adaptive polarization (AP) transmission techniques in time-varying multipath channels impaired by polarization mode dispersion (PMD) and polarization-dependent loss (PDL) AP transmission techniques considered include power gain maximization, polarization dispersion minimization for interference avoidance, polarization multiplexing with water-filling, and a suboptimal multiplexing strategy that enables direct recovery of the polarization multiplexed streams, thereby simplifying the design of the receiver Measured time-varying dual-polarized channel realizations from mobile-to-mobile experiments are used to estimate the capacity, diversity, and interference avoidance performance of the adaptive approaches

Performance of a 46-Gbps Dual-Polarization QPSK Transceiver With Real-Time Coherent Equalization Over High PMD Fiber

Abstract: We report experimental results on the transmission performance of a coherent dual-polarization quadrature phase-shift-keyed (DP-QPSK) transceiver with real-time electronic equalization over fiber having 50-ps mean polarization mode dispersion (PMD). Both single-channel, single-span and multi-channel, multi-span measurements were performed over the high PMD fiber, which has near Maxwellian statistics for the differential group delay (DGD) as well as higher order PMD as expected for a long, mode-coupled fiber. Transmission of eighty channels was achieved over 8 times100 km of TrueWave Reduced Slope fiber plus distributed high PMD fiber, where individual channels had instantaneous DGD as high as 127 ps. The dependence of the OSNR penalty on the launch state of polarization was evaluated and found to be minimal, and the contribution of fiber nonlinearities to the transmission penalty was evaluated for two different per-channel launch powers. Finally, using a transceiver equipped with forward-error-correction, error-free transmission over the 800-km link was demonstrated over a 10-day period; during this time the DGD of the measured channel varied from 13 to 116 ps.

Highly dispersive slot waveguides

Abstract: We propose a slot-waveguide with high dispersion, in which a slot waveguide is coupled to a strip waveguide. A negative dispersion of up to -181520 ps/nm/km is obtained due to a strong interaction of the slot and strip modes. A flat and large dispersion is achievable by cascading the dispersive slot-waveguides with varied waveguide thickness or width for dispersion compensation and signal processing applications. We show - 31300 ps/nm/km dispersion over 147-nm bandwidth with <1% variance.

Performance of a 46-Gbps Dual-Polarization QPSK Transceiver With Real-Time Coherent Equalization Over High PMD Fiber

Abstract: We report experimental results on the transmission performance of a coherent dual-polarization quadrature phase-shift-keyed (DP-QPSK) transceiver with real-time electronic equalization over fiber having 50-ps mean polarization mode dispersion (PMD). Both single-channel, single-span and multi-channel, multi-span measurements were performed over the high PMD fiber, which has near Maxwellian statistics for the differential group delay (DGD) as well as higher order PMD as expected for a long, mode-coupled fiber. Transmission of eighty channels was achieved over 8 x 100 km of TrueWave Reduced Slope fiber plus distributed high PMD fiber, where individual channels had instantaneous DGD as high as 127 ps. The dependence of the OSNR penalty on the launch state of polarization was evaluated and found to be minimal, and the contribution of fiber nonlinearities to the transmission penalty was evaluated for two different per-channel launch powers. Finally, using a transceiver equipped with forward-error-correction, error-free transmission over the 800-km link was demonstrated over a 10-day period; during this time the DGD of the measured channel varied from 13 to 116 ps.

Higher-Order Modal Dispersion in Graded-Index Multimode Fiber

Abstract: Previously, we proposed a field-coupling model for propagation in graded-index multimode fiber (MMF), analogous to the principal states model for polarization-mode dispersion (PMD) in single-mode fiber. That model was based on the concept of first-order principal modes, which have well-defined group delays that depend on the strength of the mode coupling. That first-order model predicts a linear relationship between the intensity waveforms at the MMF input and output. Here, we extend that model to account for higher order modal dispersion. The higher-order model predicts several effects analogous to higher-order PMD: pulse broadening, filling-in between peaks of the pulse response, depolarization and pattern blurring at the MMF output, and a nonlinear relationship between input and output intensity waveforms.

Multidimensional LDPC-Coded Modulation for Beyond 400 Gb/s per Wavelength Transmission

Abstract: In this letter, we propose a multidimensional low-density parity-check-coded modulation scheme suitable for use in up to 400 Gb/s per wavelength transmission, using currently available commercial components operating at 40 giga-symbols/s. We show that we can achieve multiples of the current transmission speed with negligible penalty. At the same time, using this scheme, the transmission and signal processing are done at 40 giga-symbols/s, where dealing with all the nonlinear effects is more convenient and the polarization-mode dispersion is more manageable. In addition, we show that using the proposed technique, we can achieve an improvement ranging from 3 dB over 8-quadrature-amplitude modulation (QAM) to 14 dB over 256-QAM, and an improvement of up to 9.75 dB over the 256-3D-constellation at bit-error ratio (BER) of 10- 9. We also show that we can reach the 400-Gb/s aggregate rate with a coding gain of 10.75 dB at BER of 10- 12.

Modal Properties of an Index Guiding Nematic Liquid Crystal Based Photonic Crystal Fiber

Abstract: This paper presents the results of the modal analysis of an index guiding soft glass photonic crystal fiber infiltrated with a nematic liquid crystal (NLC-PCF). The modal analysis is carried out using the full vectorial finite difference method which is capable of dealing accurately with anisotropic waveguide problems. The analyzed parameters are the effective index, birefringence, dispersion, effective mode area, and confinement losses for the two fundamental polarized modes. The effects of the structure geometrical parameters, rotation angle of the director of the NLC and temperature on the modal properties are investigated. The numerical results reveal that the proposed design offers high birefringence of 0.012 at the operating wavelength 1.55 mum with low losses for the two polarized modes. In addition, the structure is tailored to obtain a flat dispersion over a wide range of wavelengths with high birefringence.

PMD and PDL impairments in polarization division multiplexing signals with direct detection

Abstract: We investigate polarization mode dispersion (PMD) and polarization dependent loss (PDL) impairments in polarization division multiplexing (PDM) signals with optical polarization demultiplexing and direct detection. We find that the time alignment between the bits in the two polarizations has a significant impact on the PMD impairments, and PMD impairments also depend on the bandwidth of PDM signals, whereas PDL impairments have little dependence on the relative time alignment between the two polarizations and the signal bandwidth. We show that with a proper configuration of the polarization demultiplexing, the PDL-induced crosstalk between the two polarizations can be completely eliminated. The combined effects of PMD and PDL are also studied, and we find that, in the presence of concatenated PMD and PDL, the impairment from one effect does not enhance that from the other.

Over 100 Gb/s Electro-Optically Multiplexed OFDM for High-Capacity Optical Transport Network

Abstract: 100-Gb/s-class high-speed transmission technologies are essential to realize future 100 G Ethernet transmission over wide area networks. Optical OFDM (Orthogonal Frequency Division Multiplexing) is promising for high-speed transmission because of its narrow bandwidth and superior tolerance to chromatic dispersion and polarization mode dispersion. In this paper, we show numerically that the nonlinear tolerance of optical OFDM increases as the subcarriers is decreased and describe novel electro-optic subcarrier multiplexing scheme to generate an over 100 Gb/s high speed optical OFDM signal with a small number of subcarriers. We successfully generate a 100 G-class optical OFDM signal and demonstrate transmission over 80-km of ITU-T G.652 single-mode fiber without dispersion compensation.

Analysis of High-Speed Optical Wavelength/Time CDMA Networks Using Pulse-Position Modulation and Forward Error Correction Techniques

Abstract: This paper presents a comprehensive analysis of an optical code-division multiple access (OCDMA) network based on two distinct modulation formats, namely ON-OFF keying (OOK) and pulse-position modulation (PPM). We also investigate how each of these modulation formats performs under two distinct 2-D coding schemes, i.e., single-pulse per row (SPR) and multiple-pulse per row (MPR). For both cases, we have accounted for the simultaneous effect of many different dispersion and noise mechanisms (including multiple access interference (MAI) that impair the overall system performance. We have included the laser relative intensity noise at the transmitter side, the fiber dispersive effects (group velocity dispersion (GVD), and first-order polarization-mode dispersion (PMD), and beat, avalanche photodiode (APD), and thermal noises at the receiver side. The effect of GVD and PMD, as well as the influence of noises, on the performance of SPR and MPR codes is also investigated. Another effect studied in this paper is the influence of the APD photodetector on the beat noise of an incoherent OCDMA network. To mitigate systems noises and bit error rate (BER), we have adopted a forward error correction (FEC) RS(255, 239) algorithm in both networks investigated here. New expressions for the BER with all noises and dispersion mechanisms were also derived for the SPR and MPR code schemes. Results indicated that OOK and PPM modulation schemes without additional mechanisms to mitigate MAI and other noise effects are not sufficient to accommodate 32 simultaneous users in an error-free environment (BER < 10-12). This occurs due to the already high BER at the FEC input, which severely affects FECs at the receiver side.

Estimation of the Bit Error Rate for Direct-Detected OFDM Signals With Optically Preamplified Receivers

Abstract: In this paper, we provide a numerical bit error rate (BER) estimation approach for direct-detected orthogonal frequency division multiplexing (OFDM) signals in the presence of optical preamplified receivers. The individual BER of each subcarrier is first computed by considering their electrical signal-to-noise ratio (SNR), and then the ensemble BER is derived simply by taking the average of all the subcarriers' BERs. The calculated BER is verified by the conventional error-counting approach with high precision and is still accurate with higher quadratic-amplitude modulation (QAM) formats, even under the influences of the optical filtering and polarization mode dispersion (PMD) effects. Based on our simulation approach, the required extra power budget for 16- and 64-QAM relative to 4-QAM format are found to be ~3.8 and 8.2 dB, respectively, at a BER of 10-9. Furthermore, we use this approach to compare the receiving sensitivities and PMD tolerances for the previous proposed gapped and interleaved radio-frequency (RF)-tone-assisted OFDM systems. The results show that the gapped OFDM has a better sensitivity while the interleaved OFDM has a more PMD-tolerable capability.

Transmission of 100 Gb/s coherent PDM-QPSK over 16 x 100 km of standard fiber with allerbium amplifiers.

Abstract: We report on the performance of 100Gb/s coherent non return-to-zero (NRZ-) polarization division multiplexed (PDM-) quadrature phase shift keying (QPSK) transmission over 16x100km of standard single mode fibre under constraints of typical transparent terrestrial networks, employing Erbium-Doped Fibre Amplifiers. We first evaluate the impact of cross non linear effects onto the performance of 100Gb/s coherent PDM-QPSK signals and we investigate the impact of shifting one of the polarization multiplexed tributaries by half a symbol duration with respect to the other one. Finally we show that this solution is robust against channel-to-channel cross-talk from transparent nodes and does not suffer from performance degradation stemming from co-propagating 40Gb/s channels.

Polarization mode dispersion compensation in multilevel coded-modulation schemes using blast algorithm and iterative polarization cancellation

Abstract: Receivers and methods are provided for polarization mode dispersion compensation in multi-level coded-modulation schemes using a BLAST algorithm and iterative polarization cancellation. A receiver includes a vertical Bell Laboratories Layered Space-Time Architecture (V-BLAST) orthogonal frequency division multiplexing (OFDM) detector configured to receive input sequences and partially cancel polarization interference with respect to the input sequences to output symbol estimates for the input sequences. The receiver further includes one or more low-density parity-check (LDPC) decoders coupled to the V-BLAST OFDM detector configured to receive channel bit reliabilities and output code words. The channel bit reliabilities are indirectly calculated from the symbol estimates. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the V-BLAST OFDM detector to compensate for the polarization interference.