Multiterminal communication system and method

• US 4,924,462 A
• Filed: 01/03/1989
• Issued: 05/08/1990
• Est. Priority Date: 11/01/1988
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Norand Corporation (Baker Hughes Company)
• Inventors: Sojka, Marvin L.
• Primary Examiner(s): Olms, Douglas W.
• Application Number:
  US07/292,810
• Time in Patent Office: 490 Days
• Field of Search: 370/96, 370/90, 370/95, 370/89, 370/94, 340/825.08, 340/825.5, 340/825.51
• US Class Current: 370/449
• CPC Class Codes: H04J 3/1694 Allocation of channels in TDM/TDMA networks, e.g. distributed multiplexers Passive Optical Networks H04Q11/0062

Abstract

In an exemplary communications system a multiplicity of mobile terminals are to share a communications link with a primary processor. The primary processor may transmit a multiterminal polling signal defining a series of successive response time slots which the terminals may randomly select. A terminal wishing to send a message transmits a brief response burst in the selected time slot giving its identification. The primary processor may then sequentially poll specific individual terminals having messages to send. The primary processor may maintain a record of currently active terminals and/or of collisions (where more than one terminal seeks to transmit in the same response time slot), and as needed may automatically send e.g. with its multiterminal poll, a time slot number change, creating a greater or lesser number of time slots for future use by the active terminals. The system is thus highly adaptable on a dynamic basis during operation so as to readily maintain optimum throughput under changing conditions. As a consequence additional terminals may become active simply by transmitting their respective identifications in randomly selected response time slots. The multiterminal poll may include a listing of one or more terminals for which the primary processor has a message so that the primary processor may be assured that such terminal is available (as indicated by its response in a random time slot) before a lengthy message is sent.

Claims

1. A method of effecting communication between a primary processor means and a group of secondary processor means having respective distinctive identification means, with communication link means for affording communication therebetween, said method comprising:

(a) operating said primary processor means to transmit a polling message via said communication link means,

(b) operating the secondary processor means which receive said polling message and which have reason to respond thereto,

(b1) to select from a series of response time slots less than the number of secondary processor means, and

(b2) in the respective selected time slots, to send respective response messages which contain the respective identification means such that the primary processor means may identify respective secondary processor means of the group which have responded to the polling message, and

(c) operating the primary processor means to time the expiration of the series of response time slots defining a response time interval and after expiration of such response time interval, to initiate communication via said communication link means with a particular one of said secondary processor means which has responded to said polling messages.

2. The method of claim 1, further comprising operating said primary processor means to determine the number of secondary processor means which may respond at the time of a polling message, and when the number of said series of time slots is more or less than needed, sending a time slot number change message to said secondary processor means changing the number of said series of response time slots.

3. The method of claim 2, further comprising operating said primary processor means subsequent to the issuance of a further polling message to observe a different response time interval corresponding to the expiration of the changed number of response time slots before initiating further communications via said communication link means.

4. The method of claim 1, further comprising operating said primary processor means to automatically evaluate whether a greater or lessor number of response time slots is indicated, and as indicated sending concurrently with a subsequent one of the polling messages a time slot number change message for changing the number of said series of response time slots.

5. The method of claim 1, further comprising operating said primary processor means when the primary processor means has a message to send to a particular secondary processing means to send a polling message and contemporaneously therewith to send an identifying message containing the identification means for identifying the particular secondary processing means.

6. The method of claim 5, further comprising operating the particular secondary processing means upon receipt of the polling message and identifying message to execute a timing cycle defining the series of response time slots, to randomly select one of the response time slots, and in the randomly selected time slots sending an acknowledgement message containing its identification means.

7. The method of claim 6 wherein the polling message including the identifying message occupies a time interval not greater than the duration of a response time slot.

8. The method of claim 6 wherein a response time slot has a duration of not greater than about forty milliseconds.

9. The method of claim 8 wherein the secondary processor means and the primary processor means communicate with each other via a single channel radio frequency link.

10. The method of claim 1 wherein the primary processor means is selectively operated to reserve a specific response time slot and to transmit one of the polling messages which concurrently designates a particular secondary processing means which is to use the reserved specific response time slot.