International Business Machines Corporation

Jan G Oblonsky

John W Fennel, Jr

Robert P Barner

John A deVeer

Anne M Gulick

In a time division multiple access satellite communication system, a reference station which allocates channel capacity also regulates demand by the ground stations for that capacity. The regulation is accomplished by means in the reference station for transmitting limiting, blocking and revocation messages to the ground stations and means in the ground stations responsive to these messages to regulate the processing of input service requests. The limiting messages notify the ground stations to limit their channel usage to the channels required in the last demand message transmitted but not to exceed their last channel assignment. The blocking messages instruct the ground stations to unconditionally block any new requests for service on their input ports, rather than counting such calls as increments of demand, and thereby effectively reduce the aggregate demand in the system. When the reference station observes that a sufficient decrease in channel requirements occurs, resulting in an increasing spare capacity, it revokes the previously communicated blocking messages by a revocation message.

Demand assignment technique for TDMA satellite communication network

A new polling apparatus for units on a shared bus of a data processing system operates with a relatively slow multi signal line request bus and a relatively slow local counter. The local counter divides each time slot into a few sub-slots. Each sub-slot is assigned to two or more units in a priority sequence and during a sub-slot the assigned units contend for access to the bus by raising signals on particular lines of the request bus according to their priority within the sub-slot.

Priority system with low speed request bus

A data transmission system which includes stations connected in a closed loop configuration with interface capabilities at each station to connect to an external data processor. Through this configuration simultaneous transmission of data among processors connected to stations on the loop can be carried out by transmission of data around the loop between particular stations. Data is transmitted from a first processor to its individual station connected to the loop. This first station formats the data received from the first processor into frames of multi-bit configuration which are transmitted around the loop to a second station which is connected to a second processor. Data received by the second station is stored and transmitted to the second processor. During the time that this transmission from the first processor to the second processor is being carried out a transmission between other processors connected to stations on the loop can also be carried out. Each station on the loop receives all frames being serially transmitted around the loop and after examination of the address section of the frame will keep frames designated for that particular station and will pass on those frames addressed to other stations on the loop. Each of the stations connected in the loop is an identical unit including a clock generator and synchronizer with no master station being designated for control functions, therefore, no control lines other than a clock timing line are included in the loop. A bypass function selects an alternate path around a station on the loop to permit faulty stations to temporarily be disconnected from the loop bus. Each station has a purging capability which permits frames which have parity errors or illegitimate addresses to be removed from the loop.

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Brookeville, MD, United States of America

Jan G Oblonsky