  Integrated sensing and communication (ISAC) has been proposed as a promising
paradigm in the future wireless networks, where the spectral and hardware
resources are shared to provide a considerable performance gain. It is
essential to understand how sensing and communication (S\&C) influences each
other to guide the practical algorithm and system design in ISAC. In this
paper, we investigate the performance tradeoff between S\&C in a single-input
single-output (SISO) ISAC system with finite blocklength. In particular, we
present the system model and the ISAC scheme, after which the rate-error
tradeoff is introduced as the performance metric. Then we derive the
achievability and converse bounds for the rate-error tradeoff, determining the
boundary of the joint S\&C performance. Furthermore, we develop the asymptotic
analysis at large blocklength regime, where the performance tradeoff between
S\&C is proved to vanish as the blocklength tends to infinity. Finally, our
theoretical analysis is consolidated by simulation results.
