Synopsis of Presentation Paper ¡°QoS over Demand-Assigned TDMA Network¡± by Pang Yoke Kum Ezra


Demand Assigned Time-Division Multiplexing Access (DA-TDMA) is a type of satellite access technology that is superior compared to Frequency Division Multiple Access (FDMA) or Single Channel Per Carrier (SCPC) in terms of efficiency in satellite bandwidth usage.


In DA-TDMA, satellite bandwidth is shared among the users at different sites based on allocation of time slots rather than frequency.  Hence, all the earth stations of a DA-TDMA -based network will transmit at the same frequency, but not at the same time.  In a DA-TDMA -based network, each earth station is usually allocated a fixed percentage of satellite bandwidth (time slots).  Besides, there is a certain percentage of satellite bandwidth, which can be dynamically allocated to the earth stations, basing on users¡¯ demands.  As a result, higher efficiency in the use of satellite bandwidth can be achieved.  Due to their capability to dynamically allocate satellite bandwidth based on demand, DA-TDMA -based satellite networks are more suitable to carry ¡°bursty¡± traffic than FDMA or SCPC-based satellite networks. 


The efficiency of such satellite bandwidth usage is achieved at the expense of timing delay.  This is particularly so, as the traffic is using dynamically assigned satellite bandwidth that imposes a certain amount of delay which is proportional to the propagation delay of a typical satellite link.  Hence, it is important to investigate the effects of providing Quality of Service (QoS) over a DA-TDMA -based satellite network.