Overview of 2G and 3G Technologies

Mobile Network Identification and Location

• IMSI (International Mobile Subscriber Identity) is issued when a new mobile subscription is activated.
• The IMEI (International Mobile Equipment Identity) identifies the mobile device during network interactions.
• The MCC (Mobile Country Code) indicates the country where the mobile subscription originates.
• The MSISDN (Mobile Subscriber Identity - Integrated Digital Network) is the phone number used for calling and receiving calls.
• The MNC (Mobile Network Code) identifies the specific mobile network operator within a country.

Evolution of Cellular Networks

• The cellular network concept addresses the challenge of limited radio spectrum.
• Each cell in a cellular network consists of a base station, a coverage area, and radio channels.
• The territory is organized into cells to maximize the use of available radio spectrum.
• The cellular network concept aims to overcome the limitation of fixed radio frequency allocation.

Wireless Communication Technologies

• GPRS stands for General Packet Radio Service.
• HSPA (High Speed Packet Access, often referred to as 3G+) is a standard for high-speed data transfer.
• 2.5G technology is characterized by circuit-switched data transmission.
• LTE stands for Long Term Evolution, a high-speed, low-latency fourth-generation (4G) wireless communication technology.
• HSDPA (High Speed Downlink Packet Access) is a feature of 3G technology and offers asymmetric data transfer with higher download speeds.
• UMTS (Universal Mobile Telecommunications System) is a third-generation (3G) mobile telecommunications standard.
• EDGE (Enhanced Data Rates for GSM Evolution) is a 2.75G standard for transferring data faster than GPRS.
• WiMAX (Worldwide Interoperability for Microwave Access) enables microwave access.

Traffic Engineering and Erlangs

• 1 Erlang represents a full-time occupation of a radio channel.
• A radio channel occupied for 30 minutes during an hour transports 0.5 Erlang of traffic.
• The Erlang B formula addresses the likelihood of call blocking in a system with limited resources.
• In a system described by Erlang B, unsatisfied demand is dropped.
• Traffic intensity (A) is calculated using the formula A = λ * H, where λ is the arrival rate and H is the average call duration.
• In traffic engineering, an oversize network implies a surplus capacity.
• Fully occupying all network resources can lead to call blocking.

Mobile Roaming and Security

• TMSI (Temporary Mobile Subscriber Identity) is used to protect IMSI during roaming.
• IMSI is permanent and linked to the mobile subscriber.
• Roaming generates signaling traffic between networks.
• The system maintains knowledge of the mobile's location using location areas and cell IDs.
• Location areas are used to optimize the paging process.
• NDC (National Destination Code) determines the country for a specific mobile network.
• TMSI is used instead of IMSI when the mobile is roaming.
• The CC (Country Code) is an essential part of the IMSI.
• The HLR (Home Location Register) does not store TMSI.
• TMSI allocation is dynamic.
• The paging process determines the location of a mobile device.
• Older systems struggle to manage roaming due to complex signaling procedures.
• Roaming management aims to maintain seamless communication for roaming subscribers.
• MSC/VLR (Mobile Switching Centre/Visitor Location Register) handles roaming call routing and registration.