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First- and Second-generation Cellular Systems
Published in Goff Hill, The Cable and Telecommunications Professionals' Reference, 2012
The Digital Control Channel (DCC) carries system and paging information, coordinates access, precision synchronization signal, pilot, extended sleep mode, and others. The DCC channel includes the following: A pilot channel that is coded by Walsh code number 0: The channel contains PN pilot sequence that is a sequence of all 0's (or 1's). This channel is an unmodulated spread spectrum signal. The pilot channel is transmitted by the base station all the time on one of the active downlink CDMAOne channels. It is used for coherent detection and synchronization (timing and phase reference) for the MS operating within the coverage area of the transmitted BTS. It includes cell identifiers and sector identifiers and allows the MS to detect the strength of received signals and references for phase shift.A synchronization channel (SYNC) uses Walsh code 32 (a sequence of 32 zeros, following by 32 ones). This channel is used to achieve critical time synchronization data for the MS. With the synchronization messages transmitted on the synchronization system, the MS is able to synchronize immediately to the CDMAOne network. The SYNC channel is an encoded, interleaved, spread, and modulated spread spectrum signal that is used by MS inside the BTS coverage area.A paging channel that is used for MSs in no-communication stage: A 1.23 MHz CDMAOne signal can carry one to seven paging channels. The paging channel uses Walsh code 1 up to Walsh code 7. The paging channel is also an encoded, interleaved, spread, and modulated spread spectrum signal. The base station transmits overhead information and specific messages to the MS. It provides the MS with access information (such as assigned traffic channel), pages the MS and system information (such as neighbored cells and base stations).The Analogue Control Channel (ACC) is similar to DCC but contain less information and very basic data messages. The CDMAOne system allows analogue (EIA-553) and dual-mode (CDMAOne) subscribers to use the same analogue control channels.
An efficient attribute-based encryption scheme based on SM9 encryption algorithm for dispatching and control cloud
Published in Connection Science, 2021
Honghan Ji, Hongjie Zhang, Lisong Shao, Debiao He, Min Luo
Therefore, secure unified identity authentication, access control and authorisation management are significant topics in DCC. To find out a solution for the topics above, an effective and secure approach is to encrypt the data before storing into DCC so that only those who are authorised can access them. In detail, the control centre in SGCC distributes work tickets to workers who would operate in DCC as a registration phase. The work ticket contains the worker's unique identity information and attribute information. As Figure 2 shows, a work ticket associates a user's identity with his/her role, where the identity information is used for access control for non-core data and the attribute information is used for access control for core data. In our work, we mainly focus on the access control using attribute-based encryption (ABE).