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6.2 Design Vulnerabilities of Wireless I... > 6.2.4 Case Studies - Pg. 125

CHAPTER 6 Robust Wireless Infrastructure against Jamming Attacks 125 6.2.3. Attack Models In the following, we make few assumptions about the adversary knowledge and distinguish between two types of attackers. We assume that all sys- tem design information is available to the attack- ers. The adversary knows the protocols being used, the modulation/coding schemes, operating frequencies, logical/physical channels, contention resolution mechanisms, network discovery, chan- nel request, paging, etc. If the system allows for the use of cryptographic keys, we then consider two types of attackers: outsider and insider. An outsider attacker only knows the system design but none of the keys available only to the autho- rized members of the system. For example, in the case of spread spectrum communication, an outsider would not have access to the spread- ing code. An insider attacker is assumed to have access to a subset of the keys being used in the and the Paging Channel (PCH), are used for the subscriber channel assignment and paging notifications. A subscriber must first lock to a predefined channel of the nearby base sta- tion to monitor the broadcast control channels and send a connection request before obtain- ing a dedicated control/traffic channel for initiat- ing calls. Therefore, broadcast control channels/ mechanisms are at the heart of operating mobile communication systems in a resource-efficient way. The extensive use of control channels is not unique to the GSM system; it is a com- monly used mechanism in all cellular networks to conserve resources and allow efficient operation of the system. For example, the fourth genera- tion Long Term Evolution (LTE) wireless com- munication standard uses a Master Information Block (MIB), transmitted on the Physical Broad- cast Channel (PBCH), and is necessary for the cell search and synchronization procedure [17].