High-SNR Analysis of Outage-Limited Communications with Bursty and Delay-Limited Information

TL;DR

This paper investigates the high-SNR behavior of outage-limited fading channels with bursty, delay-constrained traffic, revealing how source burstiness scaling affects the dominant error mechanisms and system reliability tradeoffs.

Contribution

It characterizes the asymptotic error decay behavior under different burstiness scalings and identifies the optimal balance between channel errors and delay violations.

Findings

Optimal error decay depends on burstiness scaling with SNR.

At proper scaling, channel errors and delay violations are balanced.

Tradeoff exists between reliability and delay/burstiness management.

Abstract

This work analyzes the high-SNR asymptotic error performance of outage-limited communications with fading, where the number of bits that arrive at the transmitter during any time slot is random but the delivery of bits at the receiver must adhere to a strict delay limitation. Specifically, bit errors are caused by erroneous decoding at the receiver or violation of the strict delay constraint. Under certain scaling of the statistics of the bit-arrival process with SNR, this paper shows that the optimal decay behavior of the asymptotic total probability of bit error depends on how fast the burstiness of the source scales down with SNR. If the source burstiness scales down too slowly, the total probability of error is asymptotically dominated by delay-violation events. On the other hand, if the source burstiness scales down too quickly, the total probability of error is asymptotically dominated by channel-error events. However, at the proper scaling, where the burstiness scales linearly with 1/sqrt(log SNR) and at the optimal coding duration and transmission rate, the occurrences of channel errors and delay-violation errors are asymptotically balanced. In this latter case, the optimal exponent of the total probability of error reveals a tradeoff that addresses the question of how much of the allowable time and rate should be used for gaining reliability over the channel and how much for accommodating the burstiness with delay constraints.