Abstract: A manner of processing bit-interleaved data traffic in a communication network. In the increasingly-common scenario where data traffic is bit interleaved and scrambled using a PRBS (pseudo-random binary sequence) before it is transmitted from a sender to a receiver, the receiver is configured to receive the transmitted bit stream and decimate it, that is, remove the bits of the bit stream that are allocated for the receiver, prior to descrambling. To accomplish this, the receiver employs an LFSR (linear feedback shift register) similar or identical to the one used by the sender to scramble the data. The LFSR is initialized by employing helper bits inserted by the sender or an initialization unit, and may employ other techniques for phase adjustment or state skipping depending on the nature of the transmitted bit stream.

Abstract: Systems and techniques for multiple bit rate optical data transmission. A passive optical network includes an optical line termination unit (OLT) connected to one or more optical network units (ONUs) by optical elements. The OLT is capable of performing downstream transmission to the ONUs at each of a variety of different bit rates, and each ONU performs upstream transmission at one or more bit rates. The OLT can sense a bit rate of a received transmission and change its operation so as to receive and process the transmission exhibiting the sensed bit rate. Each of the ONUs receives and processes downstream transmissions at one or more bit rates, but each ONU is capable of maintaining a phase and frequency lock to downstream transmissions at all bit rates supported by the OLT. One or more of the ONUs may also receive and process downstream transmissions exhibiting different or changed bit rates.

Abstract: In a passive optical network, upstream transmission frames from an ONU to an OLT can include additional delimiters that assist in overcoming high signal distortion at the beginning of the frame that can obscure an initial frame delimiter. The second delimiter can be inserted into the frame at various locations within the frame known to the OLT such that the OLT can active a delimiter detector at the beginning of a timing window for delimiter detection. The ONU can assist the OLT in synchronizing the frame by ensuring that a frame header immediately follows a second delimiter or appears at the start of a first FEC code block following the second delimiter. Depending on where the ONU inserts the second delimiter in the frame generation process, the second delimiter may be scrambled and/or may form part of the FEC.

Abstract: In a passive optical network, upstream transmission frames from an ONU to an OLT can include additional delimiters that assist in overcoming high signal distortion at the beginning of the frame that can obscure an initial frame delimiter. The second delimiter can be inserted into the frame at various locations within the frame known to the OLT such that the OLT can active a delimiter detector at the beginning of a timing window for delimiter detection. The ONU can assist the OLT in synchronizing the frame by ensuring that a frame header immediately follows a second delimiter or appears at the start of a first FEC code block following the second delimiter. Depending on where the ONU inserts the second delimiter in the frame generation process, the second delimiter may be scrambled and/or may form part of the FEC.

Abstract: A clock and data recovery (CDR) circuit, a method of recovering a clock and data from a received raw data stream and a BI-PON optical network transceiver (ONT) receiver front-end incorporating the CDR circuit. In one embodiment, the CDR circuit includes: (1) a line rate CDR circuit having a voltage controlled oscillator, the line rate CDR circuit configured to recover a raw data stream at a receiving line rate, (2) a fixed-rate down-sampler coupled to the line rate CDR circuit and configured to down-sample the raw data stream based on a fixed-rate and (3) a variable-rate down-sampler coupled to the fixed-rate down-sampler and configured further to down-sample the raw data sample based on a variable-rate.

Abstract: In a TDMA optical network, a clock data recovery module uses signal oversampling and preamble correlation together with enhanced performance modules to extract additional data from the upstream transmission signal. Information including duty cycle, ONT power estimation, signal noise and jitter can be extracted from the upstream signal using digital logic and used to tune network components and/or alleviate network conditions.

Abstract: In a passive optical network, power consumption of the ONU can be reduced by communicating a transmission schedule from the OLT to the ONU that indicates time slots in which the ONU is scheduled to receive payload transmissions from the OLT. Components of the ONU that would normally operate continuously, including processing payloads addressed to other ONUs, are placed in a reduced power state outside of the ONU's allocated time slots.

Abstract: A signal strength corresponding to an incoming optical burst from each of a plurality of optical nodes is measured. The measurements can be performed at system start-up, configuration/installation of the optical nodes and/or at certain intervals of operation of the optical nodes. Signal strength information for the optical nodes based on the measurements is stored in memory. When scheduling the optical nodes for transmission, a preferred transmission order is determined in response to the stored signal strength information. In an embodiment, the preferred order is determined to reduce differences in signal strength levels between consecutive optical bursts.

Abstract: In a frame synchronous scrambled communications network, communications are protected from pathological bit patterns that may lead to loss of receiver lock by detecting a pathological bit pattern in an incoming traffic stream using a pathological pattern detector. When a pathological bit pattern, such as a transition-less bit pattern, is detected, a corrective bit pattern is generated and inserted or substituted into the incoming traffic stream before transmission to the receiver. The receiver can be configured to revert the modified traffic stream back to the original traffic stream.

Abstract: A manner of providing an energy-efficient two-stage PON using a multistage-PON repeater to forward data traffic and other communications between the first stage and the second stage. The multistage-PON repeater receives BI-PON transmission frames from and OLT and decimates them, forwarding data intended for end devices of the second stage. The multistage-PON repeater rate adapts the transmissions so that faster speeds may be associated with PON first stage communications and slower speeds are associated with PON second stage communications. Many though not all of the multistage-PON components are configured to operate at the slower clock speed, conserving energy. Upstream transmissions from the end devices of the second stage are buffered in the multistage-PON repeater and forwarded to the OLT according to an allocation schedule received from the OLT in a BI-PON frame.

Abstract: In a passive optical network, upstream transmission frames from an ONU to an OLT can include additional delimiters that assist in overcoming high signal distortion at the beginning of the frame that can obscure an initial frame delimiter. The second delimiter can be inserted into the frame at various locations within the frame known to the OLT such that the OLT can active a delimiter detector at the beginning of a timing window for delimiter detection. The ONU can assist the OLT in synchronizing the frame by ensuring that a frame header immediately follows a second delimiter or appears at the start of a first FEC code block following the second delimiter. Depending on where the ONU inserts the second delimiter in the frame generation process, the second delimiter may be scrambled and/or may form part of the FEC.

Abstract: A processor comprises a plurality of processor units arranged to operate concurrently and in cooperation with one another, and control logic configured to direct the operation of the processor units. At least a given one of the processor units comprises a memory, an arithmetic engine and a switch fabric. The switch fabric provides controllable connectivity between the memory, the arithmetic engine and input and output ports of the given processor unit, and has control inputs driven by corresponding outputs of the control logic. In an illustrative embodiment, the processor units may be configured to perform computations associated with a key equation solver in a Reed-Solomon (RS) decoder or other type of forward error correction (FEC) decoder.

Abstract: In a dual rate gigabit passive optical network, an optical line termination (OLT) transmits a first rate (GPON) message frame interleaved with a second rate (NGPON) message frame. An unused ATM partition of the GPON message frame is provided with a header and payload portion of the NGPON message frame so that the message frame remains at a predetermined length required by the network.

Abstract: A signal strength corresponding to an incoming optical burst from each of a plurality of optical nodes is measured. The measurements can be performed at system start-up, configuration/installation of the optical nodes and/or at certain intervals of operation of the optical nodes. Signal strength information for the optical nodes based on the measurements is stored in memory. When scheduling the optical nodes for transmission, a preferred transmission order is determined in response to the stored signal strength information. In an embodiment, the preferred order is determined to reduce differences in signal strength levels between consecutive optical bursts.

Abstract: A method and apparatus for controlling traffic in an optical network having a plurality of OLTs for communicating with a plurality of PONs. A traffic controller receives traffic information concerning current traffic volume and, preferably with reference to a rules database, calculates the number of OLTs required to support the current traffic volume. A separate determination may be made whether a network reconfiguration is permitted at this time. If a reconfiguration is permitted, the traffic controller configures a traffic control switch to route the PON traffic to an from only the calculated number of OLTs. The traffic control switch may be implemented using a voltage-controlled optical fiber coupling or electronically, routing the traffic as electrical signals to and from electro-optical converters associated with each PON. The OLTs to be used may be selected by the traffic controller.

Abstract: A routing device such as either a 1:N demultiplexer or N:1 multiplexer can provide a power dissipation proportional to log2(N) by augmenting a conventional data demultiplexer/multiplexer with additional control circuitry. The control circuit ensures that control signals that trigger configuration of individual demultiplexer/multiplexer elements are propagated only along a data transmission path. Logic components of the control circuitry enable the multiplexers to be self-configuring and to prevent multiplexers from switching to elements with empty data buffers.

Abstract: A system and method for analyzing network power consumption is disclosed. The system and method for analyzing network power consumption includes the steps of specifying at least one service which will run on said network; defining a plurality of resources provisioned in the network, each having an associated power efficiency; associating a network path with the service; calculating a sum of the power efficiencies for the resources of the network path; and outputting the sum to a display device. The system and method for analyzing network power consumption is particularly useful for identifying power consumption efficiencies throughout a communication network.

Abstract: In a passive optical network, power consumption of the ONU can be reduced by communicating a transmission schedule from the OLT to the ONU that indicates time slots in which the ONU is scheduled to receive payload transmissions from the OLT. Components of the ONU that would normally operate continuously, including processing payloads addressed to other ONUs, are placed in a reduced power state outside of the ONU's allocated time slots.

Abstract: In a passive optical network, upstream transmission frames from an ONU to an OLT can include additional delimiters that assist in overcoming high signal distortion at the beginning of the frame that can obscure an initial frame delimiter. The second delimiter can be inserted into the frame at various locations within the frame known to the OLT such that the OLT can active a delimiter detector at the beginning of a timing window for delimiter detection. The ONU can assist the OLT in synchronizing the frame by ensuring that a frame header immediately follows a second delimiter or appears at the start of a first FEC code block following the second delimiter. Depending on where the ONU inserts the second delimiter in the frame generation process, the second delimiter may be scrambled and/or may form part of the FEC.

Abstract: A communication device comprises a receiver and a data recovery module. The receiver may be an element of a serial transceiver embedded in or otherwise associated with an FPGA or other type of reconfigurable hardware. The receiver is operable with an unlocked sampling clock. The data recovery module is configured to detect transition edges in data signal samples generated by the receiver using the unlocked sampling clock, and to determine from the detected edges a sampling point for use in recovery of the associated data. The data recovery module is further configured to provide adjustment in the sampling point in the presence of transition edge variations, such as one or more exception conditions, that are attributable to the unlocked sampling clock.