Introduction to Cellular Mobile Networks
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Outline
– Circuit Switching vs. Packet Switching
– Multiplexing
– Mobile Phone Standards
– Figures
Circuit Switching
Packet Switching
Advantages of Packet Switching
– More efficient use of existing carriers
– More suited to bursty-type traffic such as Internet access.
– Compatibility with existing packet-switched networks (PSNs) such as the Internet
Advantages of Circuit Switching
– More suited to time-sensitive applications
– No contention for network resources
– Less data overheads for routing requirements
– Compatibility with existing circuit-switched networks (eg PSTN/ISDN)
Packet Routing Strategies
Connection-Orientated (CONS):
– Packet route established prior to data transfer
– Supports flow control
- Supports QoS functions
Connectionless (CNLS)
– No predefined route – packets routed individually
– No guarantee of delivery
– Difficult to implement QoS
Packet Data Delivery
Acknowledged Mode:
– Guarantees error-free delivery
– Supports flow control
– Requires additional overheads
– Lower data throughput
Unacknowledged Mode
- Packets are delivered to the network and forgotten
- No indication of delivery or error correction
- Generally relies on higher layer protocols for error detection and correction
- More efficient in reliable networks
References
– A. S. Tanenbaum and D. J. Wetherall, Computer Networks (5th Edition), Pearson Education, the book slides, 2011.
– Patrick Traynor, CS 8803 – Cellular and Mobile Network Security, Georgia Tech Information Security Center, 2012.
– General Packet Radio Service (GPRS) For Engineers, Aircom International.
