Cisco Technology, Inc.

Coreoptics, Inc.

Stefan Langenbach

Nebojsa Stojanovic

Gilberto Loprieno

Andreas Bernhard Bisplinghoff

Alessandro Cavaciuti

Norbert Beck

Negojsa Stojanovic

Prof Dr Nebojsa Stojanovic

Andreas Bisplinghoff

A first device receives a first container frame having a payload of a first length. The payload of the container frame includes multiple optical transport unit (OTU) frames, each of which includes an optical data unit (ODU) frame and a sequence of forward error correction (FEC) bits for the ODU frame. Each OTU frame is associated with a first sequence of error-identifying bits. The first device determines, for each OTU frame, a second sequence of error-identifying bits, and forms a second container frame including the OTU frames, the first sequences of error-identifying bits, and the second sequences of error-identifying bits. The first device transmits the second container frame to a second device.

Method, apparatus and system for error control

In one embodiment an apparatus, method, and system is described, the embodiment an apparatus, method including receiving a stream of data frames at an input interface, the data frames one of including security frames, or being included in security frames, wherein the security frames include payload data, performing forward error correction on the data frames a forward error correction (FEC) decoder, buffering received data frames at a buffer and blanker engine and building a complete security frame of the received data frames, determining whether or not to suppress taking a consequent action based on a frequency of authentication errors at an authentication engine, wherein the consequent action to be taken or suppressed, when taken, is taken upon payload data of one or more security frames including a data frame upon which an authentication error occurred. Related apparatus, methods and systems are also described.

Apparatus and method for avoiding deterministic blanking of secure traffic

A first device receives, over a first communications link, a container frame having a payload of a first length. The payload of the container frame includes multiple optical transport unit (OTU) frames of a second length. The first length is not a multiple of the second length. Each of the OTU frames includes an optical data unit (ODU) frame, a sequence of forward error correction (FEC) bits for the ODU frame, and a sequence of error-identifying bits for the ODU frame. The first device determines, based on the sequences of error-identifying bits, a performance of the first communications link.

A device receives signals over a communication medium and uses a low density parity check decoder to decode data in the signals. A number of unsatisfied parity checks are counted prior to a first decoding iteration of the low density parity check decoder on a basis of log likelihood ratios computed from the signals. An operational characteristic of the low density parity check decoder is computed based on an accumulated number of unsatisfied parity checks.

Accurate and fast in-service estimation of input bit error ratio of low density parity check decoders

A forward error correction and differentially encoded signal obtained via a communication channel is supplied to a soft-input soft-output (SISO) differential decoder that is bi-directionally coupled to a SISO forward error correction decoder. Over a first portion of a plurality of decoding iterations of the differentially encoded signal, the SISO differential decoder and the SISO forward error correction decoder are operated in a turbo decoding mode in which decoded messages generated by the SISO differential decoder are supplied to the SISO forward error correction decoder and forward error correction messages are supplied to the differential decoder. Over a second portion of the plurality of decoding iterations of the differentially encoded signal, the SISO forward error correction decoder is operated in a non-turbo decoding mode without any messages passing to and from the SISO differential decoder. Decoder output is obtained from the SISO forward error correction decoder.

Forward error correction with turbo/non-turbo switching

This invention relates to a method and a circuit for estimating the bit error rate in a data transmission system. Symbols are detected (u) by a maximum likelihood detector (), which provides path metrics of the decoded path and the best competitor at predetermined symbol positions. Absolute path metric differences () are calculated between the decoded path and the best competitor at said predetermined symbol positions. Events () are counted when an absolute path metric difference () is equal to one of a set of difference values. The bit error rate is estimated based on the number of counted () events (). The invention further comprises a method and a circuit in which a function is applied onto said absolute path metric difference. The function maps quantized logarithms of probabilities to probabilities.

Method and circuit for BER estimation

This invention relates to methods for obtaining a bin number of path metrics. When performing such methods, a histogram is provided, which composes a bin number of values, a maximum value and a tail region left or right of the maximum value. A bin number of path metrics is obtained from said values. According to an embodiment a local extremum is removed from said tail region. According to another embodiment the tail region is forced to be convex. According to a further embodiment a maximum metric difference between neighboring metrics is ensured.

Method for obtaining a set of path metrics and equalizer for a receiver for digital data

This invention relates to methods for obtaining a bin number of path metrics. When performing such methods, a histogram is provided, which comprises a bin number of values, a maximum value and a tail region left or right of the maximum value. A bin number of path metrics is obtained from said values. According to an embodiment a local extremum is removed from said tail region. According to another embodiment the tail region is forced to be convex. According to a further embodiment a maximum metric difference between neighboring metrics is ensured.

Methods for obtaining a set of path metrics and equalizer for a receiver for digital data

This invention discloses a self-timing method for phase adjustment. An analog signal is digitized at a first and second phase with respect to the symbols comprised in an analog signal in order to obtain first and second quantized samples. Then a first counter out of a first plurality of counters is increased if said first quantized sample has a first digital value to which said first counter is associated. Moreover a second counter out of a second plurality of counters is increased if a second quantized sample has a second digital value to which the second counter is associated. Finally the sampling phase is adjusted based on the values of the counters of the first and second plurality of counters. Moreover a digitizing, self-timing circuit is disclosed.

Self-timing method for adjustment of a sampling phase in an oversampling receiver and circuit

The invention relates to a method for channel estimation. The method comprises digitizing an analog signal representing a sequence of symbols thereby associating one digital word out to the level of said analog signal at each sampling time. The most likely sequence of said symbols is detected. To this end branch metrics are provided. According to one embodiment, a symbol period comprises at least two sampling times. Moreover, the branch metrics are obtained from frequencies of digital words resulting from a digitizing and the symbols of the most likely sequence. According to another embodiment, a symbol period comprises at least one sampling time. Events are counted wherein each event is defined by a channel state and a current digital word. Each channel state is defined by a pattern of symbols relative to a current symbol determined at the time of a current digital word. A model distribution is fitted to event counts and a branch metrics is obtained from the fitted model distribution. Moreover, the invention relates to corresponding symbol detectors for optical receivers.

Channel estimation and sequence for the reception of optical signal

This invention relates to a method for controlling an amplification within a receiver. The gain of a variable gain amplifier which amplifies an input signal to obtain a gain-controlled signal is set. Said gain controlled signal is analog-to-digital converted. Thereby digital words are generated. Each digital word has a value out of a plurality of possible digital values. Digital words having a value within a first and a second subset of the possible digital values are counted in order to generate a first and a second counter value. The gain is set in accordance with the first and second counter values in a fashion that all counter values are as equal as possible. Furthermore, this invention is related to a circuit to be used within a receiver for adjusting the gain of a variable gain amplifier in order to ensure a proper analog-to-digital conversion.

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Lauf a.d. Pegnitz, Germany

Stefan Langenbach