Performance of an admission control method for call re-attempts resulting from limiting holding time in mobile cellular systems during disasters

摘要

When a natural disaster occurs, there is a huge increase in the number of calls placed through mobile cellular systems and many are blocked due to limited radio-frequency resources. To reduce the number of blocked calls, a method limiting the holding time of calls, that reduced the call-blocking rate considerably, was proposed. However, the forced termination of some calls results in call re-attempts. We have now examined the influence of these re-attempts on the performance of the method to limit holding time. The results showed that the call-blocking rate increased greatly with call re-attempts. Thus, we proposed an admission control method for call re-attempts that significantly reduced the call-blocking rate. We also give a consideration on an appropriate number of admissions for call re-attempts.