ase with the payload information increas- ing. In addition, spectral efficiency increases with the communication reliability increasing from Case III to Case I. This is reasonable since the allocated subcarriers decrease with communication reliability increasing from Case III to Case I in Figure 14.5c, which leads to increasing spectral efficiency. Furthermore, compared with the traditional method in Case I Case II Case III Traditional method in Case II Payload information, Am (bit) Figure 14.6 Spectral efficiency with different payload information Am. References Case II, the method that was explained earlier in Section 14.4 has larger spectral efficiency, i.e. at most 700% spectral efficiency performance increases when payload information is 50 bits. This is reasonable since the method that was explained earlier in Section 14.4 is optimal in maximizing SE. 14.6 Conclusions This chapter proposed an optimal resource allocation scheme to maximize the communi- cation uplink spectral efficiency in URLLC for real-time wireless control systems. In this scheme, we considered that the URLLC service should satisfy the requirement on control convergence rate, which is formulated as a communication-control co-design problem. To solve the hybrid problem, the control requirement was converted into a constraint on the wireless communication reliability. Then, the hybrid optimization problem can be replaced by a regular wireless resource allocation problem. We proved that the converted problem is concave and an iteration algorithm is developed to obtain the optimal solution. Based on that, the optimal control convergence rate can be obtained. The simulation results showed that the method that was explained earlier in Section 14.4 achieves the maximum spectral efficiency while maintaining the control performance. The proposed co-design approach established a theoretic foundation for the URLLC serviced real-time wireless control system performance analysis and algorithm design. References 1 Popovski, P., Trillingsgaard, K., Simeo