International Business Machines Corporation

Robert W Krug

Joseph A Alvarez, Iii

John F Brennen

Joseph M Bensadon

Alexander A Smith

Norman F Brickman

Bruce D Gobioff

Michel M Colmant

John Shabe

A queue manager manages multiple interfaces among a network, a host bus and a storage means including multiple circular FIFO's in a data communication system handling packet and multimedia data transferred, in either direction, between the host bus and the network. The queue manager includes a programmable parameter RAM interface, computation logic and status means. An efficient queue management algorithm dynamically manages storage of data in the circular multiple FIFO's as data is transferred, in either direction, between the host bus and the network. System bandwidth is allocated by the queue manager to the queues which have the most activity thereby improving the speed of transferring data while reducing the amount of bandwidth that would otherwise be required by prior systems. The programmable interface permits a user to define and dynamically configure the multiple circular FIFO storage means to include other parameters useful in the management of data transferred between the host bus and the network.

Architecture for high performance management of multiple circular FIFO

A method and apparatus are disclosed for conducting broadcast, multipoint, and conference communications in a TDMA network at various data rates while simultaneously conducting point-to-point communications at other data rates, either between local ports or between geographically remote ports during time intervals within a TDMA burst, which are not necessarily predefined. The disclosed apparatus appends a direct destination address to each point-to-point port communication for transmission over a communications link, to directly address the intended destination port. The disclosed invention appends an indirect destination address to each broadcast communication transmitted over the communications link. A broadcast memory is provided at the receiving end of the communications link, for storing correlated direct addresses which are accessed by the indirect destination addresses, to directly address a plurality of intended destination ports. In this manner, both point-to-point and broadcast-type communications can be carried out for a variety of data rates, during time intervals which are not predetermined within the TDMA burst, and with a high degree of connectivity.

Time domain multiple access broadcasting, multipoint, and conferencing

A multiple data rate digital switch for a TDMA communications controller is disclosed which can service a plurality of input/output ports having many different data rates on a time divided basis, either between ports connected to the same controller or between ports connected to different, geographically remote controllers. A transmit burst buffer and a receive burst buffer are connected between the local ports and a TDMA communication link and an intranodal buffer is connected between local ports. All three buffers are accessed by a switch control memory which stores n.sub.i control words for each of the ports which are scanned m times per TDMA frame, there being a frame rate of f frames per second. Thus, the ports are selected and their data is buffered at a rate R.sub.i which is equal to the product of n.sub.i times m times f. In this manner, ports having a variety of data rates can be serviced on a time interleaved basis with maximum connectivity.

Multiple data rate digital switch for a TDMA communications controller

The position of a channel of information transmitted from a particular port is varied in response to the changing priority of that port's messages as time passes. Variable priority assignments become necessary when low speed data has been deferred in its transmission until a time just prior to the production of a second unit of data. The effect of changing the priority of deferred data messages in a TDMA burst is to change the relative position of the associated channel within the TDMA burst by means of compiling the address of that message in a higher priority threaded list. The mechanism by which a deferred data message has its priority changed from an initial low value to a subsequent higher value is by measuring the amount of time remaining for retaining a deferred data message relative to the expected time of arrival of the next data message, the impending arrival of a new message causing the priority of the deferred message to be increased, thereby increasing the probability of its successful transmission.

Dynamically variable priority, variable position channels in a TDMA burst

The transmission and reception pattern generators are synchronized for all data ports operating at the same data rate throughout an entire TDMA system. This eliminates the necessity for bit stuffing to accommodate non-integral multiple data rate data ports and yet allows data activity compression operations to be carried out.

Mechanism for synchronization of data ports in TDMA communication

To make the most efficient use of the TDMA frame for a satellite communications network, the assignment of each local station's TDMA burst duration is based on a statistical assessment of the demand by local voice and data ports. Occasionally the actual voice and data port demand at a local station exceeds that station's assigned burst duration so that some of the messages which are ready for transmission cannot be transmitted and may be frozen-out. To avoid or minimize the effects of message freeze-out, the various types of messages are categorized into a hierarchy of priorities for transmission. Messages are divided into four basic types, control signaling messages which cannot be interrupted without loss of system control, high speed data messages whose flow cannot be interrupted without the destruction of data and the need to retransmit them, low speed data messages whose transmission can be deferred for short periods, and voice messages which can be frozen-out to a limited extent without destroying the meaning of the aggregate voice signals. The subject invention deals with the architecture and operation of a digital switch at each local station which enables the messages in each priority level to be assembled in a separate respective threaded list for transmission, with the highest priority messages in the beginning of the burst and the lowest priority at the end of the burst. Thus, if a statistically greater number of messages occur than can be transmitted within the assigned burst period, only the lowest priority messages cannot be sent. A voice port prioritization mechanism is disclosed which increases the priority of voice ports as a function of the duration of their talkspurts, with those voice ports having talkspurts of longer duration being assigned to threaded lists which will be transmitted earlier in the TDMA burst.

Growing community of inventors

Rockville, MD, United States of America

Robert W Krug