Analysis and Monitoring of Paging Message in Mobile Communication System

The paging signal carries important system information of mobile communication, and the base station or Core Network (CN) can transmit some important notification to the User Equipment (UE) through paging. The paging signal triggered by the base station or the CN has no difference at the air interface physical layer. However, there are few reconnaissance studies for paging messages. As a reconnaissance party for non-cooperative reception, this paper proposes to search all possible paging occasions (POs) of the 4th and 5th Generation Mobile Communication Technology (4G, 5G), through demodulation, deinterleaving, blindly searching aggregation levels, rate de-matching, decoding and descrambling the time-frequency blocks with Paging Radio Network Temporary Identity (P-RNTI) to obtain the Downlink Control Information (DCI) of the paging message. Then after demodulation, deinterleaving, descrambling, and decoding the corresponding Physical Downlink Shared Channel (PDSCH) according to the indication of the DCI, finally the code stream of the paging message is obtained and parsed. According to the above method, the reconnaissance experiments are conducted with the actual signals to obtain the actual paging message code stream, which verifies the correctness of the proposed method. The research not only reveals the air interface transmission characteristics of paging message, but also lays an important foundation for the behavior analysis of UE and base station in 4G/5G system.