TDMA communications apparatus having adaptive burst duration

• US 4,686,672 A
• Filed: 10/10/1984
• Issued: 08/11/1987
• Est. Priority Date: 10/13/1983
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Namiki, Junji
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Scutch, III, Frank M.
• Application Number:
  US06/659,567
• Time in Patent Office: 1,035 Days
• Field of Search: 370/104, 370/99, 370/95, 370/80, 370/83
• US Class Current: 370/321
• CPC Class Codes: H04B 7/2123 Variable assignment, e.g. demand assignment

Abstract

A telecommunication system includes an earth-to-satellite-to earth link over which transmission is made on a time division basis. Each earth station assembles data to be transmitted in bursts during time period assigned to such earth station. The time position has a variable length which corresponds to the amount of data that is to be sent. The time positions are shifted to immediately follow each other with no idle and unused time space in or between adjoining time positions. Thus, each time frame is adaptively changed to fit the instantaneous communications traffic needs.

Claims

1. A time division multiple access (TDMA) communications system for enabling each of a plurality of stations served by said system to adaptively vary its own burst duration in a TDMA frame in response to their own instantaneous communications traffic needs, said system comprising:

transmit buffer memory means for temporarily storing data to be transmitted;

data assembling means coupled to said buffer memory means for assembling an output of said transmit buffer memory means into a predetermined burst format;

burst position control means coupled to control said data assembly means for shifting said assembled burst to a desired position in said TDMA frame;

transmitting means for transmitting said assembled burst into said format to a satellite;

receiving means for receiving all the bursts contained in said TDMA frames;

burst duration detector means coupled to an output of said receiving means for determining a duration of all of said received bursts and a duration of a burst at the head of said TDMA frame;

detector means for detecting when said transmitted burst is at the head of said TDMA frame; and

channel controller means responsive to an output of said detector means and to an output of the burst duration detector means for causing the burst position control means to shift said transmitted burst at each predetermined period of time while causing the burst assembling device to vary the duration of said transmitted burst.

2. A method for enabling each station to adaptively vary its own burst duration in a TDMA frame responsive to their own communications traffic needs, said method comprising the steps of:

sequentially shifting each burst in said TDMA frame at a predetermined period, said shift being an amount corresponding to a duration of a burst at the head of said TDMA frame and occurring without changing an order of said each burst; and

causing a shifted burst nearest to the end of said TDMA frame to vary the burst duration in response to a communications traffic of a station which desires a change in burst duration.

3. The method for varying the burst duration as claimed in claim 2, said TDMA frame having an initial access burst with a fixed burst duration, said method further comprising the steps of transmitting a burst in an empty time slot subsequent to said TDMA frame, and shifting said transmitted burst to a time position immediately after said initial access burst so as to enter said burst into the communications when said initial access burst is brought nearest to the end of said TDMA frame.

4. A telecommunication system comprising an earth-station-to-satellite-to-earth-station link, means in each of said earth stations for transmitting and receiving burst signals over said link during cyclically recurring time positions allocated to the corresponding earth station, said burst signals being distributed in time division multiple access time frames, said time frames including some idle and unused time capacity allocated to said burst signals for said corresponding earth stations, means responsive to detecting a start and an end of burst at any given earth station for varying the duration of said burst sent by said given earth station, whereby each station may adaptively vary its own burst duration in a TDMA frame responsive to its own communications traffic needs for eliminating the idle and unused time capacity allocated to said station;

means for shifting the time positions in said time frame so that said idle and unused capacity becomes available for other earth stations, said shift being an amount corresponding to a duration of a burst at the head of said TDMA frame and occurring without changing an order of said each burst; and

means for causing a shifted burst nearest to the end of said TDMA frame to vary the burst duration in response to a communications traffic of a station which desires a change in burst duration.

5. A telecommunication system comprising an earth-station-to-satellite-to-earth-station link, means in each of said earth stations for transmitting and receiving burst signals over said link during cyclically recurring time positions allocated to the corresponding earth station, said burst signals being sent in a format which begins with a unique word indicating the start of a burst and ends with an end of burst signal, said burst signals being distributed in time division multiple access time frames, said time frames including some idle and unused time capacity allocated to said burst signals for said corrsponding earth stations, means responsive to detecting a start and an end of burst at any given earth station for varying the duration of the time position allocated to said burst sent by said given earth station, thereby eliminating the idle and unused time capacity allocated to said station;

said means for varying the duration of the time periods comprising counter means started by said unique word and stopped by said end of burst signal for counting a normal amount of time pulses to establish the normal duration of a burst period, means for loading a normally predetermined count into said counter for enabling a count down for fixing a normally predetermined time period, means for varying said normal count down in response to the end of burst signal, whereby each earth station adaptively varies the duration of its burst transmission period in response to its own instantaneous traffic needs; and

means for shifting the time positions in said time frame so that said idle and unused capacity becomes available for other earth stations.

6. The system of claim 5 and buffer memory means for receiving and storing data responsive to incoming traffic received by said earth station.

7. The system of claim 6 and means for assembling said buffer stored data into complete signals for burst transmission to said satellite, and means for shifting said assembled data to a position in said time frame which is selected on a basis of the varied duration of allocated time positions.

8. The system of claim 7 and means for independently operating said shifting means during each of said time frames.