Efficient integration of isochronous and data bursty traffics in low earth orbit-mobile satellite systems

This paper focuses on the radio resource management in low earth orbit-mobile satellite systems (LEOMSSs) based on a time division multiple access (TDMA) air interface. A novel demand–assignment medium access control (MAC) protocol, named DRAMAþ (dynamic resource assignment multiple access}enhanced version), is proposed, where voice and Web traffic sources obtain transmission slots through requests sent by means of a random access phase. The round-trip propagation delay (RTD) of LEO-MSSs prevents an immediate feedback for each transmission attempt. Therefore, the main concern of the DRAMAþ scheme is to realize an efficient access phase. All the transmission requests successfully received at the satellite are managed by an on board scheduler. We have shown that DRAMAþ outperforms other techniques appeared in the literature in terms of voice quality, transmission delays for bursty data traffics and resource utilization. Moreover, a performance analysis of an ideal version of the DRAMAþ scheme has permitted us to prove the potentialities of the proposed DRAMAþ technique. Stability issues have been addressed as well as the impact on the DRAMAþ performance of the LEO satellite constellation RTD value. Copyright # 2002 John Wiley & Sons, Ltd.