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Browse Prior Art Database

Low Cost Time Division Multiplexing with Dynamic Bandwidth Allocation on a Satellite Channel

IP.com Disclosure Number: IPCOM000052540D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Ulmer, S: AUTHOR

Abstract

Time-division multiplexing usually requires specialized hardware to maintain timing synchronization. This hardware becomes even more complex when dynamic bandwidth allocation is required.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% of the total text.

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Low Cost Time Division Multiplexing with Dynamic Bandwidth Allocation on a Satellite Channel

Time-division multiplexing usually requires specialized hardware to maintain timing synchronization. This hardware becomes even more complex when dynamic bandwidth allocation is required.

This article describes a method in which timing synchronization is obtained from the satellite link propagation delay and the modem clock, and managed without significant resources by any Data Communication Equipment (DCE).

The proposed method will be described assuming a point-to-point link connecting earth stations A and B.

Station A sends a special signal at the time when it has just the number N of bits to send that can be transmitted during a propagation delay Tp (minus a guard time Tg). Vb (Tp - Tg) N = ------------ (1) 1000 where Vb is the bit rate of the
modem.

A propagation delay later all these bits are in the transmission channel, and the special signal arrives at station B. At this moment, station B starts transmitting. Half a propagation delay later, the bit stream from station A to station B will have completely transited the satellite transponder before the bit stream from station B to station A arrives there. Therefore, there is no collision. Another half a propagation delay later, the bit stream from station B to station A will have arrived at station A, authorizing it to transmit. This closes the circle.

Dynamic Bandwidth Allocation can be performed as follows: If a station has nothing to transmit, it still must transmit the special signal for synchronization. Its frame window (Tp - Tg) is lost. If a station has less bits to...