Investigation of spectrally efficient transmission for unequally channel spaced WDM systems with mixed data rates and signal formats

Abstract

The authors have investigated the frequency plan of channels central wavelengths allotment for wavelength division multiplexing (WDM) systems with the mixed data rates and optical signal formats. Such mixed-WDM fiberoptic transmission system (FOTS) is offered as a model for the designing of a next generation of backbone optical networks. Since the necessity for transmission of different signal formats (even with mixed per channel bitrates) over single optical fiber may arise in the nearest future as a result of telecom networks infrastructure development effort which goal is a larger systems carrying capacity (data throughput). These frequency plans were drawn applying unequal frequency intervals which values were found using the principle of intermediate value applied for channel spacings defined in ITU -T Recommendation G.694.1. The obtained more accurate frequency grid of channel central wavelength allows increase the utilization of transmission band and spectral efficiency. It is found that the improvement in transmission spectral efficiency of investigated mixed WDM system highly depends on its initial configuration -i.e. equal channel spacing value that is used for channel separation and the number of channel with the higher per channel bitrate (i.e. 40 Gbit/s) comparing with bitrate in the remaining channels (i.e. 10 Gbit/s). In general, it is revealed that for some of investigated mixed-WDM systems the transmission spectral efficiency can be increased up to 42 percent by applying proposed flexed frequency grid for channel central wavelengths.

Spectral and energy efficiency considerations in mixed-line rate WDM networks with signal quality guarantee

“…For the 40 Gbps -100 Gbps curve, λ 1 , λ 2 , λ 4 , and λ 5 operate at 40 Gbps, while ∆f 1,2 and ∆f 3,4 are both set to 112.5 GHz [8]. The values for the 10 Gbps -40 Gbps curve were computed in an earlier work [11] and reported here. From the results presented in Fig.…”

“…The OptSim block diagrams for the transmitter and receiver of NRZ-OOK and NRZ-DPSK transmitting and receiving units can be found in [11], while the transmitter and receiver description for the DP-QPSK is provided in [12]. The transmitters are driven by rectangular shape NRZ signals filtered through an electrical low pass Bessel filter.…”

Power efficiency vs. spectral efficiency and transmission distance in 2.5–10–40 Gbps backbone optical networks

“…OptSim block diagrams which represents configurations of Tx and Rx for the NRZ-OOK and NRZ-DPSK modulation formats are the same as in [12] and filters used on Tx and Rx sides are identical. Bessel electrical filters with 5 poles and bandwidth equaled to 100% of bitrate are used.…”

Investigation of Influence of Mixed Configurations on Performance of WDM-PON

“…In [4] authors propose several power efficient and cost-efficient solutions for implementation of MLR concept in high-speed long haul networks. Authors in [7] reveal that the applying unequally channel spacing in proper configuration provides increasing the SE of WDM backbone network with MLRs and MMFs. Authors in [8] also demonstrate the successful implementation of MLR transmission system with unequal channel spacing, comparing the performance of NRZ.…”