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Method for in-band error correction for SDH/SONET optical-networks using Reed-Solomon RS(244,240,9) algorithms

IP.com Disclosure Number: IPCOM000008573D
Publication Date: 2002-Jun-24
Document File: 17 page(s) / 2M

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for in-band error correction for SDH/SONET optical-networks using Reed-Solomon RS(244,240,9) algorithms. Benefits include improved system simplicity and utilization, improved programmer productivity, and improved error correction.

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Method for in-band error correction for SDH/SONET optical-networks using Reed-Solomon RS(244,240,9) algorithms

Disclosed is a method for in-band error correction for SDH/SONET optical-networks using Reed-Solomon RS(244,240,9) algorithms. Benefits include improved system simplicity and utilization, improved programmer productivity, and improved error correction.

Background

              A conventional telecommunication network is characterized as optical when pulses of light convey information from an origin to a destination. The means of transmission is optical fiber. Optical transmission has numerous advantages over conventional electrical transmission that makes it preferable for networks, including:

·        Lack of electromagnetic interference (EMI)

·        Low attenuation

·        Enormous bandwidth (BW) availability

·        Light-weight cables

              The International Telecommunications Union (a United Nations organization) publishes a series of international standards for optical communications that are collectively known as Synchronous Digital Hierarchy (SDH). The SDH standard has seriously taken into consideration former standards (of local validity), such as the Synchronous Optical Network (SONET) standard (a contribution of the American National Standards Institute and others). As a result, SDH and SONET overlap a great deal and, typically, can both be accommodated within an application.

              The SDH/SONET frame is characterized by its elements, the octet (8-bits) and the hierarchical multiplexing structure (STM-N/STS-3N). The frame duration remains constant (125 µs) independently of the hierarchical level (N). Data processing occurs in the electrical domain. Transmission occurs in the optical domain. All-optical networks with no electro-optical conversions are still an ideal.

              Optical transmission equipment has disadvantages as well, including:

·        Nonlinear and sometimes random-appearing results

·        Calibration and tuning difficulties during long-term operation (aging), sometimes resulting in the occasional injection of errors in traveling messages in the form of bursts

              One strategy for dealing with potential errors is forward error correction (FEC). Error-correction (EC) data escorts the payload-data to enable the detection and correction of the errors, provided the frequency of error-occurrence does not exceed a certain limit. The advantage of FEC is that retransmissions are avoided (up to a predefined extent), eliminating delays. FEC also provides warnings on network status and is transparent to the customers. The requirement for EC data increases the bit rate.

              A code is a set of distinct symbols. Reed-Solomon (RS) algorithms are a

subclass of the Bose, Chaudhuri, Hocquenghem (BCH) cyclic-codes. They are

symbolized as RS(nn,kk,bb), where bb is the symbol’s bit-length (which is constant),

kk is the number of symbols of which the useful message (payload) consists, and nn

is the number of symbols of which the full message (codeword) consists, including the

additive EC symbols.

      The algo...