Browse Prior Art Database

Data Concentration Method

IP.com Disclosure Number: IPCOM000083758D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 57K

Publishing Venue

IBM

Related People

West, RL: AUTHOR

Abstract

Consider a time division multiple access (TDMA) high-speed communication facility; for instance a time divided space satellite transponder channel. Effective use of the facility for voice and data communication, requires intensive block multiplex concentration at each transmission/reception access node.

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Data Concentration Method

Consider a time division multiple access (TDMA) high-speed communication facility; for instance a time divided space satellite transponder channel. Effective use of the facility for voice and data communication, requires intensive block multiplex concentration at each transmission/reception access node.

A time multiplex frame configuration suitable for such usage may be subdivided into fixed-length control and traffic signaling segments, and each traffic segment may be further subdivided into nonoverlapping nodal access bursts (Fig. 1). The control segment may be used to maintain network synchronism and to exchange connection control information required for demultiplex handling. The traffic burst segments may be assigned to various access nodes for traffic signaling and have varied durations according to demand.

The number of ports simultaneously in service at a nodal switching and traffic concentration center (Fig. 2) may exceed the number N-M of block multiplex channels actually available, to carry traffic in the assigned traffic burst segment. The technique employed to accomplish this is akin to time assigned speech interpolation (TASI) handling of long-distance telephone voice communications. This description deals with application of interpolative handling to block multiplexed data.

For interpolative handling, an initial M-channel subsegment of each transmitted traffic burst (Fig. 1) is reserved for conveying a digital activity mask, whose bits have ordered association with the in-service sensing ports at the associated access node. The bits having marked 1 status designate the origin ports, whose block multiplexed transmissions are being carried in the remaining N-M channels of the burst. No more than N-M mask bits of a traffic burst are allowed to be set to marked state. The selection may be prioritized, with data granted precedence over encoded voice (telephone) traffic and "important" data gaining precedence over casual terminal inquiries, etc.

Information indicating current associations of mask bits and nodal access ports, is preexchanged between access nodes via control signaling segments of multiple frames and maintained in storage at nodal concentration centers. Also, information indicating connection associations of sending and receiving ports of different nodal centers, is similarly preexchanged and stored. With this information and received masks received, traffic bursts are demultiplexed into blocks and distributed at suitable bit rates to appropriate outlet ports.

Fig. 3 indicates exemplary apparatus for giving efficient interpolative handling service to a group of slow-speed data signaling ports, without wasteful "bit stuffing" or "source tagging".

Consider the block multiplex transmission ("up-link") process first.

Assume modems M1, M2,...Mj are associated, respectively, with j concurr...