Communication system
First Claim
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1. A communication system comprising:
- a central station (1) having means (5,3) for transmitting synchronizing signals each defining the beginning of a time slot and means (4) for selecting the intervals between synchronising signals from different integral multiples of a time slot and for providing to said transmitting means signals corresponding to said intervals; and
a number of sub-stations (6,61) each having means (10,11,12) which is responsive to the timing of the synchronising signals and which is operative to transmit a message in a time slot selected from a number of time slots together forming a frame, the duration of said frame being determined by said synchronizing signals.
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Abstract
In a dynamic frame length slotted ALOHA system the synchronizing signals are transmitted by a base station at different frequencies (each having a period equivalent to a multiple of the time slot period). The different frequencies denote different frame lengths and the central stations detect these frequencies and select a frame length accordingly.
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Citations
7 Claims
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1. A communication system comprising:
- a central station (1) having means (5,3) for transmitting synchronizing signals each defining the beginning of a time slot and means (4) for selecting the intervals between synchronising signals from different integral multiples of a time slot and for providing to said transmitting means signals corresponding to said intervals; and
a number of sub-stations (6,61) each having means (10,11,12) which is responsive to the timing of the synchronising signals and which is operative to transmit a message in a time slot selected from a number of time slots together forming a frame, the duration of said frame being determined by said synchronizing signals. - View Dependent Claims (2, 3)
- a central station (1) having means (5,3) for transmitting synchronizing signals each defining the beginning of a time slot and means (4) for selecting the intervals between synchronising signals from different integral multiples of a time slot and for providing to said transmitting means signals corresponding to said intervals; and
- 4. A central station for a communication system which also includes a number of sub-stations, the central station comprising means for transmitting to each sub-station synchronising signals each defining the beginning of a time slot and means, responsive to the observed occupancy of time slots by signals received from the sub-stations, for selecting, in accordance with a predetermined algorithm, the intervals between the synchronising signals from different multiples of a time slot and for transmitting signals corresponding to said intervals to said transmitting means.
Specification