An information-theoretic approach to queuing in wireless channels with large delay bounds

Queuing theory allows the design of communication links that can provision for Quality of Service (QoS) in time-varying channels, such as mobile wireless channels, by considering an idealized queuing system that abstracts out the physical layer. Similarly, information theory allows the design and analysis of channel codes that can guarantee low decoding error probability by adapting to the time-varying channel. Whereas other researchers have attempted cross-layer design methods that combine these two approaches, these have been limited to specific choices of practical channel codes. There have been few attempts to combine these two theories to specify the ultimate limit of delay-constrained communications. This paper presents an approach that obtains a QoS exponent, by combining the queuing and information theoretic models; in particular, by considering information-theoretically optimal channel codes. Calculations show that such a joint approach yields substantial improvement in QoS performance in a variety of communication scenarios.