International Business Machines Corporation

Charles Robert Young

Gordon Taylor Davis

Malcolm Scott Ware

Jeffrey Haskell Derby

Ajay Dholakia

Fredy Daniel Neeser

Hua Ye

Dongming Hwang

Youssef Abdelilah

Donald E Carmon

Fetchi Chen

Gary G Allran

Robert John Schule

Jose A Eduartez

Raymond W Weeks

Charles R Knox

Llewellyn B Marshall

Nathan A Mitchell

William L Lawton

Malcolm C Ware

Michelle Chan Granholm

Data rate control systems, methods, and computer program products in which an error counter is maintained that contains an error count. The error counter is periodically sampled to determine a sampling interval error count corresponding to a change in the error count since a previous read of the error counter. The sampling interval error count is provided to a first filter that is characterized by a slow time-constant and a second filter that is characterized by a fast time-constant. The first filter generates a slow-filtered sampling interval error count while the second filter generates a fast-filtered sampling interval error count, which are used as a basis for generating a data rate slowdown request signal. More specifically, the data rate slowdown request signal is generated if either the slow-filtered sampling interval error count or the fast-filtered sampling interval error count exceeds a threshold respectively associated therewith. Advantageously, the first filter, which is characterized by a slow time-constant, may be used to respond to lower numbers of errors that are sustained over an extended time period while the second filter, which is characterized by a fast time-constant, may be used to respond to large error bursts spanning a shorter time period. Moreover, by filtering the errors accumulated during each sampling interval, sensitivity with respect to the position in time of a given error burst relative to boundaries between sampling intervals may be avoided.

SYSTEMS, METHODS, AND COMPUTER PROGRAM PRODUCTS FOR CONTROLLING DATA RATE REDUCTIONS IN A COMMUNICATION DEVICE BY USING A PLURALITY OF FILTERS TO DETECT SHORT-TERM BURSTS OF ERRORS AND LONG-TERM SUSTAINABLE ERRORS

Methods, systems and computer program products are provided for monitoring performance of a modem which obtain diagnostic data directly from memory associated with the modem's digital signal processor (DSP). A secondary path to the DSP memory is utilized for the monitoring operations so that real time data can be obtained during connection startup procedures and during an active connection. First-in first-out (FIFO) buffers are incorporated in the DSP memory to track state transitions of one or more of the state machines within the modem and various performance data measurements may be obtained directly from the DSP memory responsive to different state transition events. The real time collected data may be stored in a file and provided to a remote location for use in diagnosing customer problems with specific customer line connections. Accordingly, real time monitoring of digital and analog line conditions and modem performance may be utilized to diagnose problems with modems and line connections.

Methods, systems and computer program products for monitoring performance of a modem during a connection

Re-synchronization of sets of transmit and receive state variables in a communication system is achieved when an error is detected, without disrupting the connection. Each of first and second transceivers, connected by a communications channel, have a common set of transmit and receive state variables supporting a data encoding algorithm function. The transmitter of one of the first and second transceivers fist encodes data to be transmitted and updates the transmit state variables according to the data encoding algorithm and the receiver of the receiving transceiver validates whether or not each data block has been received correctly. During the process of decoding the data, the receive state variables are updated according to the same algorithm used to update the transmit state variables, thereby keeping the two sets of state variables in synchronism with each other. When an error is detected, re-synchronization occurs by switching to transparent mode in the direction of communication in which the error occurred and resetting the corresponding transmit and receive sets of state variables.

Data compression over communications links which are exposed to occasional errors

Broadband modems using data compression insure the physical connection between modems is solid prior to initiating error recovery procedures since its error detection runs on the compressed data. Escape sequences applicable to Transparent Mode of the Compression function enable both duplex and simplex compression functions and provide a more reliable mechanism for completion of error recovery procedures in the presence of subsequent line disturbances. Transparent Mode is used during the re-synchronization procedure. No special compression code words are required to accomplish the procedure, and there is no reduction in the number of code words available for actual compression encoding. The procedure works regardless of whether compression is being used in both directions, only one direction, or neither direction. A new Transparent Mode Command to request that the remote modem send a RESET Command is defined. The new command is termed RRESET.

System and method for resynchronization of transmit and receive compression dictionaries

A data processing system for executing multimedia applications which interface with multimedia devices that consume or produce at least one of real-time and asynchronous streamed data includes a CPU for execution of one or more multimedia applications and a DSP for processing data including streamed data. A plurality of modular multimedia software tasks may be called by the multimedia application for execution in the DSP. A plurality of data communication modules are provided for linking selected ones of the software tasks with selected others of the software tasks, and linking selected multimedia devices with selected ones of the software tasks. Each of the communications modules allows continuous, real-time and unidirectional communication of streamed data. The modularity of the processing system defines an open architecture for real-time processing which allows additional modular multimedia tasks to be added to the software tasks and selectively linked to at least one of (a) selected ones of the software tasks, and (b) selected ones of the multimedia devices. A DSP manager is resident in the CPU which dynamically monitors resource allocation to allow at least one software task to be loaded and executed while at least one other software task is being executed by the DSP without interference with execution.

Method and apparatus for facilitating real-time and asynchronous loading

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Cary, NC, United States of America

Charles Robert Young