Duty Cycle Division Multiplexing Research Articles

Design of Optical Fiber Transmission System Based on Absolute Polar Duty Cycle Division Multiplexing (APDCDM)

This paper propose a new multiplexing technique which use the bipolar RZ signal to realize duty cycle division multiplexing (DCDM) ,we call it Absolute Polar Duty Cycle Division Multiplexing (APDCDM).Multiplexing and demultiplexing principle of APDCDM are analyzed. Here we have designed a optical fiber transmission system based on APDCDM of three users by Joint simulation with Optisystem and Matlab. Simulation result shows the feasibility of this system. By the analysis of signal energy, explain APDCDM can carry more users than DCDM.

Influence of guard band on performance of absolute polar duty cycle division multiplexing over a single wavelength and wavelength division multiplexing system

For the first time to the best of our knowledge the effect of guard band (GB) on the performance of 40Gb/s Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) over a single wavelength and wavelength division multiplexing (WDM) are investigated and reported. It is demonstrated that the spectral width occupied by 40Gb/s AP-DCDM with GB is 100GHz (with minimum spectral efficiency of 0.4b/s/Hz) whereas, this value can be reduced to around 80GHz for AP-DCDM without GB (with minimum spectral efficiency of 0.5b/s/Hz). In addition to better spectral efficiency, this amount of saving in the spectral width leads to ∼60ps/nm improvement in chromatic dispersion tolerance. In this paper, characteristics of AP-DCDM with and without GB over WDM system are compared at the speed of 40Gbit/s per WDM channel, for the tolerance to narrow optical filtering and minimum allowed channel spacing. The AP-DCDM without GB has narrower spectral width than AP-DCDM with GB, which makes its implementation in WDM system advantageous.

Proof-of-Concept Experiment of Duty Cycle Division Multiplexing with Bit Error Rate Analysis

Demultiplexing concept of Duty-Cycle Division Multiplexing (DCDM) technique is tested in the back-to-back connection and after transmission over copper wire and optical fiber. Three different lengths of copper wire are tested with the total loss of 3.3, 6.6, and 9.9 dB respectively. Even though the sampling points and threshold values were not dy- namic, the demultiplexing process for the case of back-to-back, and after transmission over the links with 3.3, and 6.6 dB losses, was successful without experiencing any errors. This can be witnessed when the recovered data is compared against the transmitted bits. However, the errors are recorded in the link with 9.9 dB losses, which was mainly due to the non-optimized sampling points and threshold values. In experiment over 60 km Standard Single Mode Fiber, successful transmission was demonstrated. The receiver sensitivity is calculated off-line by using bit error rate analysis. These results confirm the validity of DCDM demultiplexer structure including the sampling process and the data recovery rules.

Self-Phase Modulation Effect on Performance of 40 Gbit/s Optical Duty-Cycle Division Multiplexing Technique

Self-phase modulation (SPM) effect on perfor- mance of 40 Gbit= s( 3� 13.33 Gbit=s) optical duty-cycle division multiplexing (O-DCDM) over 400 km (5 � 80 km) standard single mode fiber (SSMF) based on three dif- ferent dispersion compensation schemes is investigated by simulation. The result shows that the SPM effect is very strong in dispersion pre-compensation compared to post- compensation. Further reduction in SPM effect is observed by combination of pre- and post-compensation with the op- timum pre-compensation value of around 215 ps=nm. The simulation is performed at different launched power into dispersion compensation fiber (DCF). The range between � 6 to � 8 dBm is observed as the optimum power for all dis- persion compensation schemes. The highest SPM threshold is observed when dispersion pre- and post-compensation are used together, which is around C6:7 dBm. In addition, the optimum range of launched power into SSMF for differ- ent transmission distances from 80 km to 1280 km is also presented.

Performance enhancement of Absolute Polar Duty Cycle Division Multiplexing with Dual-Drive Mach–Zehnder-Modulator in 40 Gbit/s optical fiber communication systems

We modeled and analyzed a method to improve receiver sensitivity of the Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) transmission system by using Dual-Drive Mach–Zehnder-Modulator (DD-MZM). It is found that by optimizing the bias voltage in DD-MZM, the sensitivity of the AP-DCDM can be improved. The optimizations lead towards the larger eye opening. As opposed to the previous work, in terms of receiver sensitivity and dispersion tolerance, similar performance for all channels was achieved. In comparison to the previously reported AP-DCDM system, this work resulted in almost 3.6dB improvement of the receiver sensitivity, came together with acceptable chromatic dispersion tolerance.

70-Gb/s amplitude-shift-keyed system with 10-GHz clock recovery circuit using duty cycle division multiplexing

The performance of ASK over DCDM for up to seven channels is reported. The aggregate bit rate of 70 Gb/s is achieved with only 160-GHz modulation bandwidth. The clock and data recovery are realized at 10-GHz clock rate, which is very economic and efficient. At 7 × 10 Gb/s, the worst receiver sensitivity of −10 dBm, OSNR of 41.5 dB and chromatic dispersion tolerance of ±7 ps/nm are achieved. Whereas, for the best channel, the receiver sensitivity, OSNR, and chromatic dispersion tolerance are −23.5 dBm, 29 dB, and ±36 ps/nm, respectively.

Effect of self-phase-modulation on dispersion compensated absolute polar duty cycle division multiplexing transmission

The effect of self-phase modulation (SPM) on 40 Gb/s absolute polar duty cycle division multiplexing (AP-DCDM) is investigated and reported. The study includes the influence of launched power, number of channels and dispersion compensation method. Dispersion post-compensation and combination of dispersion pre- and post-compensation are used to manage the transmission links. At high powers, SPM degrades the pulse recompression process and provides an upper bound on the AP-DCDM transmitted pulse energy. It is demonstrated that the 40 Gb/s AP-DCDM system shows a 4.1 dB improvement and less than 1 dB penalty in terms of SPM tolerance in comparison to 40 Gb/s 4-ary and on off-keying (OOK) systems, respectively. The SPM effect is stronger in the 100 post-compensated link than that in the combination of pre- and post-compensated links. Dispersion pre-compensation of 18 22 is found as the optimum range of pre-compensation ratio for AP-DCDM system, which makes optimisation of the launched power possible.

Duty-Cycle Division Multiplexing: Alternative for High Speed Optical Networks

Performance of 3×10 Gbps duty-cycle division multiplexing (DCDM) is analyzed. The channel demultiplexing is performed electronically at single user bit rate (10 Gbps). At 30 Gbps, null-to-null spectral width of 80 GHz is measured for DCDM technique which is 33.3% less compared to 30 Gbps conventional return-to-zero (RZ). In this system, the worst channel required a receiver sensitivity of around -25.6 dBm at bit error rate (BER) 10-9. The chromatic dispersion tolerances of the system are 210.5 and 236 ps/nm for the worst and the best channel respectively.

Duty-cycle division multiplexing (DCDM)

A multiplexing technique, which is based on duty-cycle division, is proposed. The channel multiplexing and demultiplexing are performed electrically at the single user bit rate, which is very economic. In a three-user system (3×10 Gb/s), the simulation results show that the best receiver sensitivity value achieved is −30.1 dBm with an optical signal-to-noise ratio (OSNR) of 22.3 dB, while the chromatic dispersion tolerance ranges from 192 to 280 ps/nm. Migration from 30 to 120 Gb/s is achieved with the penalty of 6.4 and 5.2 dB in the receiver sensitivity and OSNR, respectively, for the worst user.

Absolute polar duty cycle division multiplexing over wavelength division multiplexing system

The performance of absolute polar duty cycle division multiplexing (AP-DCDM) over wavelength division multiplexing (WDM) system is presented based on the simulation results. The AP-DCDM signal has narrower bandwidth than conventional time division multiplexing (TDM) signal, which makes its implementation in WDM system advantageous. In this paper, characteristics of AP-DCDM and TDM signals in WDM system are compared at the speed of 40 Gbit/s per channel, for the minimum allowed channel spacing and the chromatic dispersion tolerance. The results clearly show that AP-DCDM performs significantly better than TDM. By using AP-DCDM, 1.28 Tbit/s (32 × 40 Gbit/s) was successfully transmitted over 320 km standard single mode fiber. Spectral efficiency of 0.64 b/s/Hz was achieved by using 10 Gbit/s transmitters and receivers without polarization multiplexing.

Analysis of return-to-zero-on-off-keying over absolute polar duty cycle division multiplexing in dispersive transmission medium

We propose and investigate a technique to reduce the spectral width as well as increase the tolerance to chromatic dispersion (CD) using improved return-to-zero (RZ) on-off-keying (OOK) over absolute polar duty cycle division multiplexing (AP-DCDM) technique. The proposed channel multiplexing and demultiplexing are performed electrically using only one modulator for n number of users, which is very economical. It is demonstrated that the spectral width occupied by 30 Gb/s RZ-OOK without AP-DCDM measured at −20 dB from the peak power is around 105 GHz whereas, this value can be reduced to around 64 GHz for 30 Gb/s RZ-OOK over AP-DCDM. This amount of saving in the spectral width is a significant achievement, which leads to better tolerance to CD. Its tolerance to CD is in the range of ±109 and ±155 ps/nm, for the worst and the best users, respectively. These values are higher than that of 30 Gb/s conventional RZ-OOK, which is around ±86.5 ps/nm. At 120 Gb/s RZ-OOK over AP-DCDM (the worst user) has pre-amplified receiver sensitivity and optical signal to noise ratio (OSNR) of −22.5 dBm and 28.57 dB, respectively.

Realization of high capacity transmission in fiber optic communication systems using Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) technique

An electrical multiplexing technique, namely Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) is reported for high-speed optical fiber communication systems. It is demonstrated that 40 Gb/s (4 × 10 Gb/s) AP-DCDM system shows a clear advantage over conventional 40 Gb/s RZ-OOK with 50% duty cycle in terms of dispersion tolerance and spectral efficiency. At 40 Gb/s its tolerance to chromatic dispersion (CD) is 124 ps/nm and 194 ps/nm for the worst and the best user, respectively. These values are higher than that of 40 Gb/s RZ-OOK, which is around 100 ps/nm. The spectral efficiency, receiver sensitivity and OSNR for different number of channels are discussed. Comparison against other modulation formats namely duobinary, Non-Return-to-Zero (NRZ)-OOK and RZ-Differential Quadrature Phase-Shift Keying (RZ-DQPSK) at 40 Gb/s are made. It is shown that AP-DCDM has the best receiver sensitivity (−32 dBm) and better CD tolerance (±200 ps/nm) than NRZ-OOK and RZ-DQPSK. In reference to duobinary, AP-DCDM has better receiver sensitivity but worse dispersion tolerance.

A novel economical duty cycle division multiplexing with electrical multiplexer and demultiplexer for optical communication systems

Duty cycle division multiplexing (DCDM) is proposed as an alternative multiplexing technique. In this technique, the channel multiplexing and demultiplexing are performed electrically. This technique allows aggregate bit rate to be recovered at the single channel bit rate, which is very economic. In this paper, we examine three channels system where each channel operates at 10 Gb/s over a single optical carrier. Performance of the system is evaluated based on back-to-back receiver sensitivity, optical signal-to-noise ratio (OSNR) and chromatic dispersion tolerance. The performance comparison is made against return-to-zero (RZ) format. The results show that, DCDM can support higher amount of chromatic dispersion than that RZ. At 3 × 40 Gb/s, a receiver sensitivity and OSNR of −16.8 dBm and 34.6 dB is respectively required for the worst DCDM channel.