Standards Development

Scope

The proposed International Standard defines a procedure for calculating the root-mean-square error vector magnitude (EVM) of optical n-state amplitude-phase-shift-keyed (n-APSK) signals from a set of measured symbols. It specifically defines a procedure for normalizing the reference states as well as a procedure for optimal scaling of the measured symbol states. The procedure is applicable to single-polarized optical signals and to conventional polarization-multiplexed signals with independently modulated polarization tributaries.

The proposed standard does not specify any signal processing steps needed to extract the symbols from the received optical signals, because these steps depend on what type of optical receiver is used and also on the type of the transmitted n-APSK signal. These and other possible signal processing steps are to be defined in application-specific standards or documents.

If approved, this standard will be part of the IEC 61280-2 series, which is dedicated to fibre optic communication subsystem test procedures for digital systems. 

Purpose

Specific aims and reasons for this standardization activity

The increasing use of coherent receiver technologies in fibre optic communication systems facilitates the t ransmission of optical complex vector modulated signals, such as four-state quadrature phase-shift-keyed (QPSK) or 16-state quadrature amplitude-modulated (16QAM) signals. After being first introduced in long-haul communication systems, coherent transmission technology is now increasingly deployed in medium- to short-reach systems, such as for data centre interconnects and intra-data-centre links, where interoperability of transmission equipment from different manufacturers has become highly desirable.

In this context, the error vector magnitude (EVM) is an important quantity, because it allows characterization and comparison of the quality of vector modulated signals generated by equipment from different vendors. However, thus far there is no generally referable standard that defines a procedure for calculating the EVM of more complex vector modulated signals, like 16QAM, where the normalization of the reference states and of the measured states needs to be defined and agreed upon.

The proposed standard establishes a generally applicable procedure for calculating the EMV of single-polarized and polarization-multiplexed optical n-APSK signals. It will be useful to manufacturers and users of telecommunication equipment and optical test instruments as well as to other standardization bodies, Timeliness of the activity There are increasing activities in various standardization bodies and multiple-source-agreement consortia to define standardized interfaces for interoperable fibre optic transmission equipment, including the definition of criteria to assess such interoperability, which include the use of EVM. Feasibility of the activity There are no known factors that could hinder the successful establishment or general application of the proposed standard, such as patents or restrictions imposed by regulatory bodies.

WG 1 of SC 86C has 67 expert members from 16 countries, who represent a wealth of expertise and knowledge in the field of fibre optic communication systems and subsystems