Joint Security and QoS Provisioning in Train-Centric CBTC Systems Under Sybil Attacks

The security and Quality-of-Service (QoS) provisioning are two critical themes in urban rail communication-based train control (CBTC) data communication systems, which can directly affect the train's safe operation. In this paper, we design the novel train-centric CBTC systems using train-to-train (T2T) wireless communication with the innovative security check scheme. The local security certification and cooperative security check are proposed to detect and defense the Sybil attack based on the CBTC T2T communications. The quantized Age of Information (AoI) is used as an integrated QoS and security indicator of the train-centric CBTC data communication systems. The proposed AoI indicator fully considers the impact of the packet drop and re-transmission, Sybil attack, and the cooperative security check on CBTC systems. The policy-based asynchronous reinforcement learning is utilized to improve the integrated AoI performance. The simulation results show that the proposed cooperative security check scheme with the optimization model can achieve improved integrated AoI performance, compared with the traditional security check scheme. Moreover, with the help of the cooperative security check scheme, we detect and defense the Sybil attack against the train-centric CBTC systems with much higher probability.