  This paper studies the performance of Non-persistent CSMA/CA protocols with
K-Exponential Backoff scheduling algorithms. A multi-queue single-server system
is proposed to model multiple access networks. The input buffer of each access
node is modeled as a Geo/G/1 queue, and the service time distribution of
head-of-line packets is derived from the Markov chain of underlying scheduling
algorithm. The main results include the complete analysis of the throughput and
delay distribution, from which we obtained stable regions with respect to the
throughput and bounded mean delay of the Geometric Retransmission and
Exponential Backoff schemes. We show that the throughput stable region of
Geometric Retransmission will vanish as the number of nodes n \rightarrow
\infty; thus, it is inherently unstable for large n. In contrast to Geometric
Retransmission, the throughput stable region of Exponential Backoff can be
obtained for an infinite population. We found that the bounded mean delay
region of Geometric Retransmission remains the same as its throughput stable
region. Besides, the variance of service time of Exponential Backoff can be
unbounded due to the capture effect; thus, its bounded delay region is only a
sub-set of its throughput stable region. Analytical results presented in this
paper are all verified by simulation.
