Load Estimation and Connection Request Barring for Random Access in Massive C-IoT

Cellular Internet of Things (C-IoT) is a new term referring to access technology introduced by 3GPP to support IoT applications. C-IoT has several advantages compared to the unlicensed low-power wide area (LPWA) technology. However, C-IoT's random access (RA) procedure is easily overloaded by massive access from IoT applications. This article proposes a novel mechanism which combines a simple algorithm to assess the instantaneous load and a dynamic tuning of the contention level on the third message of RA. The technical consideration for integrating our mechanism to the existing C-IoT system is also presented. Performance evaluation is conducted under several practical scenarios. The results show that our proposed mechanism brings a significant increase of normalized throughput with the cost of just a slight increase of the access delay compared to the original system. Additional performance comparisons with the other existing approaches which target similar problem are also included. The results show that our mechanism performs well, especially when considering how simple it is to be implemented.