Achieving Deterministic Delay in Industrial Internet of Things: Resource Allocation Schemes in the Finite Blocklength Regime

Industrial control scenarios impose strict requirements on wireless communication networks, especially deterministic delay. Due to limited communication resources and time-varying wireless channels, transmission delay varies randomly, resulting in high jitter. To ensure deterministic delay, we model the jitter as the variance of transmission delay and formulate delay variance minimization problems by jointly optimizing transmission power and blocklength in the finite blocklength regime. The challenge of this research is that the delay variance formula couples multiple time slots together. Two typical communication scenarios, namely, the transmit power-limited case and the transmit energy-limited case, are considered. In the power-limited scenario, we consider the maximum transmit power constraint and propose a variance recursive formula-based scheme to decouple the variance minimization problem. As for the second case, an average energy constraint is additionally considered, and a Lyapunov-based scheme is proposed. We further propose low-complexity iterative algorithms to address the above non-convex problems. Numerical results demonstrate the superiority of our proposed schemes over the state-of-the-art ones in terms of reducing jitter. Furthermore, we reveal the trade-off between the average delay and delay variance, highlighting the necessity for tailored system design and reasonable resource allocation.