Transmission Convergence Layer of NG-PON2 in VPIphotonics Tool

Passive optical networks are the most promising solution for access networks. The first standard provided only 155 Mbit/s but current networks work according to ITU-T G.984.3 with 2.5 Gbit/s in downstream. However, NG-PON2 offers up to 40 Gbit/s in downstream by 4 different wavelengths. This article deals with an implementation of transmission convergence layer in VPIphotonics. This tool is dedicated only for simulations of physical layer. The main aim is to present a simulation of physical layer for NG-PON2 in comparison with our implementation of transmission convergence layer and encapsulated frames according to ITU-T G.989.3. Our results confirm expanding the entire system reach with the real encapsulation method of 3 sublayers model and error correction mechanism. The 3 sublayers model can be easily extended to all passive optical networks simulations in VPIphotonics simulation tool

Modified GIANT Dynamic Bandwidth Allocation Algorithm of NG-PON

Gigabit passive optical networks have been widely deployed due to the fact that the cost of their implementation is still decreasing. What is more important, we are facing theproblem with increasing demands on the transmission bandwidth. Regarding this issue, the ITU develops another two standards supporting higher downstream bitrate. The XG-PON standard is the first platform under the developing, and the NG-PON2 is the second standard. The first one provides compatibility and increases the downstream capacity of 10 Gbit/s and the second standard has the same assumptions, but does not have backward compatibility. In this article, we discuss only XG-PON networks. We choose amendment as the dynamic bandwidth allocation algorithms, and we have compared it with the original specification and with our modification. The primary intention of that modification is to reduce the delay of Triple Play (data, video, and voice) services. These services are represented by TCONT (Transmission Container), which is used to improve the PON system upstream bandwidth allocation and transmission status dynamically. As NS-3 simulator does not support the direct mapping of Triple Play services into T-CONT and their labeling. We focus on a delay value for Triple Play services which was reduced by own modification in a GIANT algorithm. On the other hand, we cannot reduce the delay value for VoIP services because it has the highest priority by T-CONT

Phase-Noise Characterization in Stable Optical Frequency Transfer over Free Space and Fiber Link Testbeds

Time and frequency metrology depends on stable oscillators in both radio-frequency and optical domains. With the increased complexity of the highly precise oscillators also came the demand for delivering the oscillators’ harmonic signals between delocalized sites for comparison, aggregation, or other purposes. Besides the traditional optical fiber networks, free-space optical links present an alternative tool for disseminating stable sources’ output. We present a pilot experiment of phase-coherent optical frequency transfer using a free-space optical link testbed. The experiment performed on a 30 m long link demonstrates the phase-noise parameters in a free-space optical channel under atmospheric turbulence conditions, and it studies the impact of active MEMS mirror stabilization of the received optical wave positioning on the resulting transfer’s performance. Our results indicate that a well-configured MEMS mirror beam stabilization significantly enhances fractional frequency stability, achieving the−14th-order level for integration times over 30 s

Multi-purpose infrastructure for dissemination of precise stable optical frequency

Long distance precise frequency and accurate time transfer methods based on optical fiber links have evolved rapidly in recent years, demonstrating excellent performance. They are attractive both for very high-performance applications and as a secure alternative complement to radio- and satellite-based methods. In this paper, we present development of infrastructure for such transmission containing 700+km of transmission lines, with planned cross border optical frequency connectivity. According to our knowledge, this will be the third such line globally. The infrastructure also shares fibers with existing data transmissions, both amplitude and phase modulated, which poses high demands on mutual isolation and insensitivity to cross talks

Alternative spectral windows for photonic services distribution

Optical fibers are becoming commonly used beside data transmissions for dissemination of ultra-precise and stable quantities or alternatively as distributed sensors of for example acoustic and mechanic vibrations, seismic waves, temperature etc. There have been developed methods for these transfers and their stabilization, allowing thus to achieve excellent performances. Such performance is bound with utilization of single physical medium for both ways of propagation. These methods are attractive both for very high-performance applications and as a secure alternative complementary to radio and satellite-based transfer methods. From economical point of view, sharing fibers with regular data traffic is an advantage, especially for longer distances and large infrastructures. Unfortunately, the most often used wavelengths are located almost in the middle of telecommunication band. Due to continuous data traffic growth and utilization of flexible spectral allocation, the collision in wavelength plan will occur more and more often. In this paper we overview alternative wavelengths suitable for these transfers, we also propose suitable methods for all-optical reach extension, by all-optical amplification. Shared line design allowing transfer of ultra-stable quantities in three different spectral bands is proposed and such design is evaluated.</p

Alternative spectral window for precise time fiber based transport

Precise time and also stable frequency transfers are approaching the state to become almost standard applications for optical fiber networks, especially they are becoming supported in multiple research and education networks. In principle, the time and frequency transfers are not possible to be implemented over data transport layer, which hasn't been was designed for essential stability, and thus dedicated wave band is required for such implementation. To achieve even better stability for precise time and stable frequency, the bidirectional transmission in single physical medium (fibers and ideally all components along the route) is preferred. The White Rabbit system combines synchronous Ethernet and Precise Time Protocol (IEEE-1588) and it has been designed in the CERN with the aim to provide time synchronization among large number of sensors, actuators and other devices utilized in experiments. Primary aim was the operation over single fiber (to avoid nonreciprocal changes in directions) using standard telecommunication transceivers designed for single fiber operation with reach limited to about 40 km. In this paper, we experimentally verify and compare stability of White Rabbit system operation over long distances up to 300 km using active optical amplification on wavelengths which should not be utilized within spectrum needed for regular data transmissions.</p