Frame level control for collision mitigation in orthogonal code hopping multiplexing

• Published in: IEEE Wireless Communications and Networking Conference, 2005 Vol. 2; pp. 701 - 706 Vol. 2
• Main Authors: Sung Ho Moon, Jae Kyun Kwon, Dan Keun Sung
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2005
• Subjects: Channel coding; Collision mitigation; Degradation; Delay; Downlink; Level control; OFDM; Performance gain; Probability; Spread spectrum communication
• ISBN: 0780389662; 9780780389663
• ISSN: 1525-3511; 1558-2612
• DOI: 10.1109/WCNC.2005.1424593

We have recently proposed an orthogonal code hopping multiplexing (OCHM) scheme which is based on a statistical multiplexing scheme for orthogonal downlink in direct sequence spread spectrum systems. This is a feasible candidate for accommodating a large number of bursty packet-based users with good backward compatibility. In OCHM, code-collisions which degrade channel coding performance and result in an increase in the required E/sub b//N/sub 0/ are inevitable for obtaining a statistical multiplexing gain. In this paper, we lower code-collision probability by discarding or delaying excessive frames whose number is larger than a threshold value. It reduces the required E/sub b//N/sub 0/ at the transmitter and saves system power. However, there is an increase in BLER (block error rate) or delay. Therefore, there exist trade-offs between the required E/sub b//N/sub 0/ and BLER (or delay). We can determine an operating point which can reduce the required E/sub b//N/sub 0/ by considering how much BLER or delay the system requires as a target value.