Lucent Technologies Inc.

Bell Telephone Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Joseph Elide Landry

Mark A Bordogna

Warren Clifton Trested, Jr

Philip Sidney Dietz

Jeffrey Robert Towne

Mark Aldo Bordogna

Warren Clifton Trested

Joseph F Carriere

Dewayne Alan Spires

Philip J Baun, Jr

Stephen K Eng

Wilmer B Gaunt, Jr

John Henry Green

Thomas M Nolan

David C Rhodes

Jonghee Lee

Distributed switch fabrics can support multiple switching functions while meeting established performance requirements by using a control architecture based on multiple layers of signal status carried within signals transported through the distributed switch fabrics. More specifically, a method and apparatus is provided for controlling the selection of signals through distributed switch fabrics by deriving signal status information for the signals at any point along a transmission path and embedding the signal status information in each of the signals using multiple signal status layers. Each of the signals carries its respective signal status information as it propagates along the transmission path, so that the embedded signal status information can be selectively extracted from any of the multiple signal status layers to facilitate a selection decision at any of the distributed switch fabrics. The multiple layers of signal status can be used to provide a cumulative signal status of a particular signal as it propagates along the transmission path or the multiple layers can be used to support various combinations of status control, such as each layer being used to track a different level or type of status for the signal.

Control architecture using a multi-layer embedded signal status protocol

A simple, elementary switch fabric is provided for switching individual signals as a composite group based on group signal status that is embedded and carried within each of the individual signals in the group. In general, a group signal status is derived for a group based on the signal status of each of the individual signals within that group. This group signal status is then individually encoded and embedded in each of the individual signals in the group. The embedded group signal status can be extracted and decoded at any point within the transmission path, as necessary, to facilitate appropriate switching decisions. Although each individual signal is switched independently by the elementary switch fabric, the individual signals are effectively switched as a composite group because the switching decision for each individual signal in the group is based on the same group signal status. That is, individual signals in a particular group will either be selected or rejected together as a single, composite group.

Method and apparatus for switching signals using an embedded group signal status

A system for providing segmented control of a single, homogeneous routing structure, such as a switch fabric, includes application control elements that are each responsive to embedded signal status information for each of the input signals to the switch fabric. Within each of the application control elements, a configurable arrangement of selectors and control logic is used to provide domain segmented control of each of the separate switching functions for a particular application. Each application control element performs an application specific address resolution function to resolve a single address of one of the input signals based on the embedded signal status of each of the input signals. This single address is provided to the switch fabric so that the corresponding input signal can be selected at the switch fabric output. Because embedded signal status is provided locally at each selection point within the application control element, the control functions for each of the separate switching functions are decoupled, and, as a result, each of the separate switching functions can be independently controlled as a separate domain within the application control element. The single, homogeneous switch fabric simultaneously supports multiple applications in parallel because each of the application control elements is used to control a separate output from the switch fabric. Because of the one for one association between application control elements and switch fabric outputs, the switch fabric is effectively 'channelized' whereby each channel of the switch fabric supports a separate application.

Control architecture for a homogeneous routing structure

A network element with a centralized switch fabric is able to support multiple switching functions while meeting established performance requirements by using a control system based on an embedded signal status protocol. Generally, each input signal within a transmission path is monitored to derive signal status information, which is then individually encoded and embedded within the input signal. The embedded signal status can be decoded and provided as input to control logic for processing at any point within the transmission path, as necessary. In the case of a centralized switch fabric, the control logic resolves an address of a single input signal based on the embedded signal status and provides this resolved address to the switch fabric so that the appropriate input signal can be selected. In the present invention, the control logic may be configured to support any given application, e.g., 'path-in-line' protection switching, whereby each configuration of control logic constitutes an application control set that supports the performance requirements of that given application.

Control architecture using an embedded signal status protocol

A channel bank unit for interfacing baseband user signals with a PCM carrier communications channel. The channel bank unit includes a circuit allowing verification of the transmission interity between the channel bank unit and external equipment having two-way communication with the channel bank unit. The circuit includes a first portion for evaluating the reception integrity of signals received from the external equipment and a second portion for imposing a parity sense on the signals transmitted to the external equipment that is related to the evaluation results of the first portion.

D-5 Channel bank control structure and controller

A reduction in idle channel noise and crosstalk in a mid-riser-biased successive approximation encoder is achieved through the use of two polarity decisions. Encoder (401) assigns a sampled analog input signal to the closest one of a multitude of discrete signal levels or code steps. A comparator (109) provides this assignment by successive comparisons of the sampled signal with a series of reference signals (110). Each comparison produces a binary digit. The first comparison, or polarity decision, is not transmitted and instead coupled to feedback circuitry (401) to reduce any dc component in the analog input signal to substantially zero. A second polarity decision is then made using a non-zero offset reference signal (402) corresponding to an intermediate position on a code step, typically the midpoint. The non-zero offset reference signal is applied along with subsequent reference signals to the comparator to determine the closest code step. The binary digit from the second polarity decision, along with the binary digits representing the code step, are coupled to the encoder output. Accordingly, the encoder is now biased at the intermediate position to substantially reduce the likelihood of idle channel noise and crosstalk enhancement.

Noise and crosstalk reduction in mid-riser biased encoders

A data link is additionally provided in a digital channel bank type transmission system without displacing or degrading any present voice or signaling channel capacities. The additional data channel is obtained by 'borrowing' a major portion of the signaling subframe channel. A transmit circuit (FIG. 3 and FIG. 8) serves to time division multiplex a data channel into the signaling subframe channel by transmitting the signaling framing pattern in an intermittent periodic manner with preselected data bits interposed therebetween (waveform TDATA of FIG. 5). At the remote receiving terminal, a subframe recovery circuit (FIG. 7) serves to recover the signaling framing pattern embedded in the multiplexed subframe channel. A receive circuit (FIG. 4) at the remote terminal is responsive to a signal from the subframe recovery circuit to separate out the data bits in the multiplexed subframe channel.

Data link for digital channel bank systems

In a digital channel bank, the binary signaling states (on-hook, off-hook) are updated periodically for each channel. Some number (n .gtoreq. 2) of the most recent of these samples are stored at the receive end of the digital system for each message channel. Under normal working conditions the output (to the switching machine) is directly influenced by the incoming real-time samples. However, when a carrier disturbance (i.e., out-of-frame condition) is detected, the updating process is stopped and the output is controlled by the older stored bits. That is, instead of sending the real-time signaling information of each channel to the switch, the signaling bits that were received and stored during a previous frame (e.g., 12 or more frames earlier) are now coupled to the switch. This assures a high probability that the proper signaling state is presented to the switch during short carrier disturbances.

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Atkinson, NH, United States of America

Joseph Elide Landry