'Institute of Electrical and Electronics Engineers (IEEE)'
Doi
Abstract
Provision of guaranteed quality of service (QoS) in
wireless communication has always been a demanding task. QoS
can be ensured by the mechanism of repeat request, however
real time systems can tolerate only a finite delay. In this paper
we investigate the problem of provision of guaranteed QoS by
hybrid automatic repeat request (HARQ) schemes, based on soft
outputs of a channel decoder. Focus is on adaptive interleavedivision
multiple access (IDMA) transmission. Such a system is
able to provide virtually arbitrary bit error rates (BER).
The proposed HARQ schemes use the reliability information
provided by the channel decoder to decide whether a packet
satisfies the quality of service (QoS) requirements. QoS can be
specified in terms of a minimum required throughput/data rate or
a minimum required BER. Effect of truncation of repeat requests
on the bit error rate and packet throughput is investigated. An
adaptation scheme based upon the bit error rate in the accepted
packets is proposed and the effect of the adaptation on the
effective throughput is demonstrated