What is meant by access control? What are the contention-based and contention free access control mechanisms?
Access Control: When two or more stations are connected with each other using the same link(multipoint or broadcast link), there is a need of multiple access protocol to coordinate access to the link, which decides when and which station should be access the link.
Contention based access: nIN this method no station is superior to another and none is assigned the control over another. There is no rule to specify which station should transmit next, so there is a competition among the stations for using the link.
Contention free access: Contention-free access is a state of operation for wireless networking nodes. In this method, the node is able to use the Point Coordination Function, as opposed to the Distributed Coordination Function, within a wireless LAN. A device that is able to use point coordination function is one that is able to participate in a method to provide limited Quality of service (for time sensitive data) within the network.
Explain the concept of frequency reuse in cellular systems.
Write short note on
Iridium satellite system
Briefly describe the congestion control, slow start and fast retransmit mechanism.