A Survey of Satellite Communications System Vulnerabilities

The U.S. military’s increasing reliance on commercial and military communications satellites to enable widely-dispersed, mobile forces to communicate makes these space assets increasingly vulnerable to attack by adversaries. Attacks on these satellites could cause military communications to become unavailable at critical moments during a conflict. This research dissected a typical satellite communications system in order to provide an understanding of the possible attacker entry points into the system, to determine the vulnerabilities associated with each of these access points, and to analyze the possible impacts of these vulnerabilities to U.S. military operations. By understanding these vulnerabilities of U.S. communications satellite systems, methods can be developed to mitigate these threats and protect future systems. This research concluded that the satellite antenna is the most vulnerable component of the satellite communications system’s space segment. The antenna makes the satellite vulnerable to intentional attacks such as: RF jamming, spoofing, meaconing, and deliberate physical attack. The most vulnerable Earth segment component was found to be the Earth station network, which incorporates both Earth station and NOC vulnerabilities. Earth segment vulnerabilities include RF jamming, deliberate physical attack, and Internet connection vulnerabilities. The most vulnerable user segment components were found to be the SSPs and PoPs. SSPs are subject to the vulnerabilities of the services offered, the vulnerabilities of Internet connectivity, and the vulnerabilities associated with operating the VSAT central hub. PoPs are susceptible to the vulnerabilities of the PoP routers, the vulnerabilities of Internet and Intranet connectivity, and the vulnerabilities associated with cellular network access

Trade-off between power consumption and delay in wireless packetized systems

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 82-86).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.In packetized wireless systems, coding allows reliable transmission of multiple packets colliding at a receiver. Thus data may not need to incur delays such as those due to back-off schemes in traditional ALOHA systems. However, there is a trade-off between delay and power consumption. Recent work in this area has considered the case where multiple users are aware of the states of other users' queues. We consider a time-slotted multiple user system with random packet arrivals. The size of the packets and probability of arrival together represent the burstiness of the system. The time slots are considered to be long enough that capacity can be achieved over a single slot in a sense we define. We consider the difference in average power consumption when average delay, in terms of slots, is minimized, with and without knowledge of other users' queues. We also consider the case where average power is minimized without regard for delay. We present and analyze a simple scheme with limited information sharing about queues' states. Our scheme uses a hybrid multiple access/broadcast type code for the case of low queue lengths and a multiple access scheme in the case of large queue lengths. We show how this scheme allows trade-offs between power consumption and delay.by Todd P. Coleman.S.M