ng that the network may have some spare resources to accept more UEs. Hence, from the number of admissible UEs viewpoint, the performance of QoS-AC policy may not be good. Moreover, the number of admissible UEs is also one of the key performance measures for UE admission control policy. Therefore, we propose Num-AC policy based on the solution to P2 to further optimize the number of admissible UEs. By analyzing the optimal solution to P2, we find that the smaller I'n or d* is, the more likely the rate or delay of UE n can be satisfied. Based on this observation, we develop Num-AC policy to find the admissible UE subset, which is denoted by AN-A The basic idea of this policy is trying to add the UEs with small value of rn and d* into set AN-A. First of all, the UEs with Y'n = 0 and d = 0 = are definitely admissible to the network. Hence, AQ-A C AN-A We then try to find more admissible UEs from set V\AQ-A, and add these UEs into AN-A The details of Num-AC policy are summarized as Algorithm 9.1. Algorithm 9.1: Algorithm of Num-AC policy. Require: problem P2 formulated in (2). Ensure: set of admissible UEs AN-A Initialization Stage: 2: obtain the optimal solution i**, d* and by solving P2 3: add all UEs with y==0 and dn 0 into AN-A Search Stage: 4: find UE i: 6: obtain the optimal solution d* and x* by solving P2 with respect to Atemp 7: .A.comp 8: AN-A Go back to line 4 10: else 11: break 12: end if 13: output AN-A In the initialization stage, we add the definitely admissible UEs (i.e. the UEs with Y* = 0 and dn=0). = Then in the search stage, we check the feasibility of other UEs one by one. The smaller the value of (++) is, the more likely the UE is admissible. Hence, we check the UEs with the smallest value of (++) first. To reduce the computational complexity, once a UE is unfeasible for the network, we terminate the check, and then obtain the set AN-A. Therefore, this policy needs to solve P2 at most IV times in the worst case. 9.1 A Framework of User Access Control for RAN Slicing 9.1.4 Experiments, Results, a