Transmission Performance Comparison Research Articles

Nonlinear transmission performance comparison employing 60 × 416.7-Gb/s TPS-64QAM and UD-16QAM systems with limited bandwidth.

The impacts of limited bandwidth on the nonlinear transmission performance are investigated by employing a truncated probabilistic shaped 64-ary quadrature amplitude modulation (TPS-64QAM) and a uniformly distributed 16-ary quadrature amplitude modulation (UD-16QAM) over a bandwidth-limited 75-GHz spaced 25-Tb/s (60 × 416.7 Gb/s) 6300-km transmission system. In terms of nonlinear performance measured by optimal launch power, theoretical analyses show that a 0.4-dB improvement could be introduced by UD-16QAM with respect to TPS-64QAM over a 6300-km transmission without limited bandwidth. However, contrary results would be observed that TPS-64QAM would outperform UD-16QAM by about 0.8 dB in terms of optimal launch power when the impacts of limited bandwidth are considered. Besides, numerical simulations and experimental results could both validate that about 1.0-dB optimal launch power improvement could be obtained by TPS-64QAM under bandwidth-limited cases, which is roughly similar to the results of theoretical analyses. Additionally, WDM experimental results show that all 60 tested channels could agree with the BER requirements by employing TPS-64QAM, further validating the superiority of TPS-64QAM compared to UD-16QAM under bandwidth-limited cases.

Straightening of the rollers of planetary roller screw — Design of straightening die and experimental validation

The roller of a Planetary Roller Screw (PRS) is prone to bending deformation and runout error after carburizing, which results in the uneven transmission performance, increased transmission friction, and decreased service life. Traditional grinding methods used to rectify these errors have high costs and low efficiency and furthermore reduce the thickness of the carbon layer of the roller. This paper proposed a new radial feed-in straightening method to correct the geometric errors of carburized PRS rollers. Trial tests are first performed to explore the feasibility of different straightening techniques, as well as to discover key factors for the rational design of a straightening die. Based on the trial tests, a new tooth profile model of the straightening die for the PRS roller is proposed. Finite element models are developed to analyze the material flow feature of the straightening process, as well as to verify the effectiveness of the proposed tooth profile model of the straightening die. For mass production needs, experimental tests are performed to further examine the performance of the proposed straightening method. It is found that reducing the tooth contact interference between the roller and die can effectively increase the quality of the straightened workpiece. Results show that the bending deformation and runout error of the carburized PRS roller are effectively corrected by the proposed straightening process. Furthermore, the smoothness of the tooth surface of the roller is significantly increased, and all the tested samples meet production quality standards after straightening. A comparison of transmission performance under 0.3 million cycles shows that the maximum friction torque (1.82 N·mm) of the PRS product with straightened rollers is much better than without straightening (105.70 N·mm).

Transmission Performance Comparison of 16*100 Gbps Dense Wavelength Division Multiplexed Long Haul Optical Networks at Different Advance Modulation Formats under the Influence of Nonlinear Impairments

Abstract Higher spectral efficiency and data rate per channel are the most cost-effective approaches to meet the exponential demand of data traffic in optical fiber network communication system. In this paper, diverse modulation formats are analyzed for Dense Wavelength Division Multiplexed system at 100 Gbps * 16=1600 Gbps data rates. The performance analysis of proffered system for Non-Return to Zero, Return to Zero, Carrier- Suppressed Return to Zero and Duo binary RZ with duty cycle 0.5 to 0.7 ranges like modulation formats are considered to find optimum modulation format for a 100 Gbps bit rate per channel optical fiber transmission network system. The simulations are analyzed for different values of input power, length of fiber, nonlinear refractive index, nonlinear dispersion and nonlinear effective area for all above mentioned modulation formats with spacing 100 to 250 GHz. to evaluate the effect of modulation format Fiber Bragg Gratting, optical fiber amplifier and Dispersion Compensation Fiber dispersion compensation techniques are enacted on this proposed optical network system.

Transmission performance comparison of 128-SP-QAM and PM-16QAM in a WDM system

We numerically and experimentally compared the BER performance of 128-level set-partitioning quadrature amplitude modulation (128-SP-QAM) and polarization multiplexed 16-ary quadrature amplitude modulation (PM-16QAM). From our experimental results and numerical simulation, it can be concluded that 128-SP-QAM has significant BER improvement compared to PM-16QAM when optical signal to noise ratio (OSNR) is high. However, when it comes to low OSNR scenario such as transmission over a very long distance, 128-SP-QAM and PM-16QAM have similar performance.

Transmission Performance Comparison for 100-Gb/s PAM-4, CAP-16, and DFT-S OFDM With Direct Detection

Metro network, as a medium distance transmission system, poses a special challenge of transmission capacity and cost. In this paper, we present a detailed comparison of applying three advanced modulation formats including pulse amplitude modulation-4 (PAM-4), carrierless amplitude and phase modulation-16 QAM (CAP-16), and discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S OFDM) with low-cost direct detection for 100-Gb/s/λ metro optical transmission systems. These modulation formats are all experimentally demonstrated with similar digital signal processing algorithms. Three kinds of chromatic dispersion (CD) compensation ways named CD precompensation method, single sideband (SSB), and dispersion compensating fiber (DCF) are also compared. Two types of modulators including an IQ modulator and a dual-drive Mach–Zehnder modulator are employed to generate SSB or CD precompensated signals in this experiment and their transmission performance is also evaluated. To the best of our knowledge, this is the first time that the performance of single-wavelength 100-G signal transmission based on direct detection is evaluated over 480 km of standard single mode fiber with PAM-4, CAP-16, and DFT-S OFDM modulation formats.

Experimental Comparison of Transmission Performance for Nyquist WDM and Time–Frequency Packing

Several spectral efficient solutions for next-generation flexible optical networks are under investigation in order to cope with scalability issues while traffic demand is continuously increasing. Concerning transmission, Nyquist wavelength-division multiplexing (NWDM)—that confines the bandwidth within the Nyquist frequency of the signal—recently gained a momentum as one of the most suitable solutions for transmission over backbone networks and commercial solutions are available by now. Besides NWDM, other transmission techniques have been proposed to approach or overcome the Nyquist limit, thus further increasing the spectral efficiency (SE). Among them, time–frequency packing (TFP) is one candidate. This method builds a superchannel, whose subcarriers significantly overlap in frequency or time or both. This leads to an increased SE at the expenses of additional complexity within the transceiver to compensate for the introduced intersymbol interference. In this paper, we experimentally compare, for the first time, NWDM and TFP when employing the same identical test-bed. The experiment considered the two different terabit superchannels: a polarization multiplexed (PM)-16 quadrature amplitude modulation for the case of NWDM case, and a PM-quadrature phase-shift keying for TFP. The comparison and assessment of the results is carried out first in back-to-back configuration and, afterward, by propagating them over a recirculating loop consisting of a standard single-mode fiber, including spectrum selective switch to emulate node filtering.

Research on the transmission performance of turbo codes in DDO-OFDM system

A direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) system using turbo codes is built, and the transmission performance comparison between coded system and uncoded system is analyzed. Three decoding algorithms, which are Log-maximum a posteriori (MAP), Max-Log-MAP and threshold Max-Log-MAP, are used in the turbo coded system. By comparing three decoding algorithms, the system using Max-Log-MAP algorithm has the best bit error rate (BER) performance. At the transmission distance of 240 km, the uncoded system with transmission rate of 30 Gbit/s can get the BER performance at the degree of 8.93×10−3 with optical signal to noise ratio (OSNR) of 24 dB, while the turbo coded system with transmission rate of 50 Gbit/s can achieve it within OSNR of 20 dB.

A Study on a Differentiated Service Queuing Scheme Based on Transmitted Bytes Within a UMTS Core Network Gateway

Universal mobile telecommunications system (UMTS) is a popular 3G system to support network applications full of variety. According to the quality of service (QoS) features of four types of UMTS traffic, this study proposes a BBQ (byte-based queuing) scheme to handle a UMTS packet forwarding process in differentiation. With the BBQ scheme, four types of UMTS traffic depend on their QoS features to receive differentiated packet forwarding performance within a UMTS core network. Several scenarios are simulated to realize the packet transmission performance of the BBQ scheme. Moreover, a packet transmission performance comparison between the IETF RIO scheme and the BBQ scheme is discussed in this study. The simulation results show that a differentiated packet forwarding behavior among UMTS traffic can be provided by the BBQ scheme with low cost operation/architecture; this demonstrate the effectiveness of the proposed queuing scheme.

40 Gbps WDM Transmission Performance Comparison Between Legacy and Ultra Low Loss G.652 Fibers

G.652 standard single-mode fiber (SSMF) is today considered as the most efficient solution to transport 40 Gbps and 100 Gbps data traffic over ultra long-haul distances on terrestrial transport networks. In the early 2000s, there was a trend to replace legacy G.652 fibers, which were strongly impaired by polarization mode dispersion (PMD), by G.655 fibers. For economic reasons, incumbent operators decided to keep their legacy G.652 fiber infrastructure, while replacing gradually the most impaired fibers by low PMD G.652 fibers over the links transporting the highest amount of traffic. In this context, we performed in 2009 an experimental evaluation of the performance of a new ultra low loss (ULL) and low PMD G.652 fiber to carry 40 Gbps WDM systems over ultra long-haul distances by using various modulation formats (NRZ-OOK and NRZ-DPSK) and amplification schemes (hybrid Raman-EDFA and EDFA only). We demonstrated record transmission distance of 4400 km at 40 Gbps line rate when NRZ-DPSK was combined with hybrid Raman-EDFA amplification. We complete here this previous study with new results, coming in particular from an extensive experimental and numerical comparison of the transmission performance of this new ULL G.652 fiber with the legacy G.652 fiber, used in the field for 20 years. We demonstrate in particular that this new SMF-28 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> ULL optical fiber increases the maximum transmission reach by ~30%, whatever the amplification scheme, when NRZ-DPSK is used.

Experimental Comparison of Transmission Performance of Multichannel OFDM-UWB Signals on FTTH Networks

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The experimental demonstration of radio-over-fiber Wimedia-defined OFDM ultrawide band (OFDM-UWB) wireless transmission in fiber-to-the-home (FTTH) networks using standard single-mode fiber with lengths ranging from 25 to 100 km is reported in this paper. </para>

Transmission Performance Comparison between Dispersion Compensation Fiber and Reverse Dispersion Fiber in High Rate DWDM Dispersion Compensation Frame

We propose and demonstrate the experiment transport of 8 channels 20 Gbit/s dense wavelength division multiplexing (DWDM) system structure that consists of Erbium doped fiber amplifier (EDFA) and large effective area fiber (LEAF) as a positive dispersion fiber. Negative dispersion compensation fiber employing dispersion compensation fiber (DCF) and reverse dispersion fiber (RDF) measure the transmission length and system performance. The proposed 8 channels 20 Gbit/s DWDM system structure is in L band wavelength range. L band wavelength range is between 1570.42 nm∼1576.02 nm, channel spacing 100 GHz. Dispersion compensation fiber (DCF) and reverse dispersion fiber (RDF) both have good performance of high rate in DWDM dispersion compensation frame. Good performance of Q factor should be greater than 6 dB, corresponding to a bit error rate (BER) of less than 10 -9 , and it has been measured for all eight channels [1]. This proposed system is suitable for the application in the long distance transmission communication and ultra-long haul (ULH) networks systems.

32 x 40-Gb/s dense WDM transmission over 3000 km using "double-hybrid" fiber configuration

This paper reports long-distance transmission experiments of 100-GHz-spaced 32 /spl times/ 40 Gb/s dense wavelength-division-multiplexing (DWDM) signals, designed for submarine applications. A transmission distance of 3000 km was obtained with more than 11.9-dB Q value. Keys to the achievement are the use of a novel fiber configuration and a nonlinear tolerant carrier-suppressed return-to-zero signal format for effectively suppressing the self-phase-modulation group-velocity-induced waveform degradation. The advantage of this double-hybrid fiber configuration is also confirmed by a transmission performance comparison with a quadruple-hybrid fiber configuration using 40-Gb/s-based DWDM signals.

Circulating loop simulations for transmission performance comparison of various node architectures

Optical cross-connect system comparisons are carried out in this paper with an emphasis on the transmission performance of different node architectures. We employ a photonic simulator to bypass the considerable cost and time constraints that would arise if a similar task was carried out in a laboratory. The computation times are minimized by using an optical circulating loop to create a simplified simulation configuration of an optical network. Based on the simulation results, the estimated upper limit on the number of cascadable 2 × 2 nodes is obtained for different node architectures and performance targets. Almost twice as many nodes can be traversed by a signal in systems with nodes that employ novel switching technologies characterized by high crosstalk isolation (higher than 55 dB) and/or low insertion losses compared to earlier proposed monolithically integrated node designs.

Improvement of CATV Transmission Using an Optimum Coherent Carrier System

Aiming at the development of future multichannel CATV-transmission systems the utilization of phase-coherent picture carriers is discussed as a means of reducing intermodulation-and crossmodulation-distortion arising in the line repeater amplifiers. The paper presents experimental and theoretical data for comparison of transmission performance. As a basis the non-coherent operation is reviewed. In order to evaluate the improvement by a coherent system the problem of optimum carrier phase relation is investigated. Experimental results demonstrate the suppression of distortion, if the phases are adjusted according to a certain code which was found by optimization.