Publication

Abstract : Narrowband Internet of Things (NB-IoT) is a LPWAN radio standard developed by 3GPP to provide devices with longer battery life and broader coverage. Many authors have proposed algorithms to maximise battery life by optimising devices’ Active periods. However, more research is required to develop integrity-protection algorithms for NB-IoT and study their impact on battery life. NB-IoT, being bandwidth-constrained, transmits data as truncated packets at discrete intervals to maximise battery life. However, truncated MACs reduce cryptographic strength leading to brute-force attacks. Cumulative MAC (CuMAC), generating 256-bit authentication tags by aggregating truncated MACs, alleviates this limitation. However, CuMAC is prone to replay attacks and reduced performance due to re-transmissions, resulting in delayed responses, packet loss and battery overhead. In this paper, we propose Energy-Performance CuMAC (EP-CuMAC) by modifying CuMAC to overcome inherent flaws and suit NB-IoT’s requirements. Feedback-based mechanism is developed to improve channel quality by regulating abnormal packet delays and SINR. Machine and deep learning algorithms predict and authenticate lost messages and tags to minimise re-transmissions. EP-CuMAC re-transmits the aggregated lost packets and new messages in upcoming Active state to reduce re-transmissions. Energy-performance-security trade-offs of EP-CuMAC are studied for various encryption parameters using ns-3 and Raspberry Pi. Although EP-CuMAC consumes approximately 17.73%, 33.33% and 45.59% power, memory and execution time, respectively and thrice the re-transmitted aggregated-packet authentication time compared to CuMAC, it has 68.42% enhanced packet delivery ratio and 66.66% higher security against replay attacks. Our analysis reveals that EP-CuMAC can effectively replace CuMAC as lightweight and performance-efficient alternative for NB-IoT.