WC_MODULE-1

MODULE-1 Introduction to Wireless Telecommunication Systems and Networks

1. Introduction to Wireless Telecommunication Systems and Networks

• Definition: Communication is the transfer of information from one point to another.

• Invention: Telephone invented by Alexander Graham Bell in 1876 was the first manually switched wireline network.

• Emergence of Wireless Communication: Introduced in the 20th century allowing mobile operation to electronic communication.

• Advancements: Integrated Circuit (IC) technology led to cordless telephones in the late 1970s. Public subscription for cellular telephone systems began in 1983.

• Applications: Wireless systems have applications in various sectors:

  • Commerce: For transactions and service dealings.

  • Education: Enhances learning through mobile access.

  • Defense: Facilitates secure communications.

  • Various Environments: Home, industrial, commercial, and military.

1.2 History and Evolution of Wireless Radio Systems

• Hertz's Experiment (1887): Verified existence of electromagnetic (EM) waves.

• Marconi's Wireless Telegraph (1895-1901): Developed a wireless telegraph system launching services between England and France.

Early AM Wireless Systems

• Components: Early transmitters utilized inductance and capacitance to tune the output frequency of a spark gap.

• Frequency Generation: Maximum power at lower frequencies produces radio signals of varying duration controlled by a telegraph key.

1.3 The Development of Modern Telecommunications Infrastructure

• Public Switched Telephone Network (PSTN):

  • Local Exchange: Connects subscribers via multiple methods.

  • Intra-office Calls: Managed through circuit-switched calls.

  • T-Carriers: Supporting interoffice calls.

Intra-office Call Handling

• Local Loop Connection: Utilizes copper wires for Plain Old Telephone Service (POTS). Signals are managed by local exchange switches.

• Analog Voice Signal Propagation: Through analog connections to line cards at the switch.

1.4 PSTN Interoffice Calls

• Interoffice Calls: Connects different switches using digital interoffice transmission facilities or trunk lines, often managed by T-carrier transport.

• Signaling System #7 (SS7):

  • A standardized protocol used globally for setting up telephone calls in PSTN.

  • Functions: Call setup, teardown, number translation, local number portability, SMS services.

1.5 Overview of Different Generations of Wireless Cellular Networks

• 1G Cellular Systems: Examples include Advanced Mobile Phone System (AMPS).

• Characteristics of 1G Networks:

  • Analog frequency modulation for speech and data.

  • In-band signaling used during calls.

  • Supported circuit data services but faced limitations in mobile VPN applications.

1.6 AMPS Technology Overview

• FDMA (Frequency Division Multiple Access): Allocates specific frequencies to each user, with continuous transmission requirements.

• Modem Data Rates: Peak rates from 4.8 Kbps to 14.4 Kbps.

• Channel Specs:

  • Frequency range: 800 MHz.

  • Uplink/Downlink bands:

    • Downlink: 824-849 MHz

    • Uplink: 869-894 MHz

  • Channel spacing: 30 KHz.

1.7 AMPS Network Components

• Comprises base stations, mobile stations, and mobile telephone switching offices (MTSOs).

• Base stations facilitate communication with mobile subscribers and the PSTN.

1.8 AMPS Mobile Call Operations

• Describes the process for mobile-originated and mobile-terminated calls.

• Mobile call initialization involves locking onto control channels, sending identification and confirmation messages.

• Idle Mode Tasks: Continuous processes that mobile stations perform during inactivity to maintain connectivity.

1.9 Handoff Operations in AMPS

• Handoff occurs when a mobile station transitions from one cell to another while engaged in a call.

• Involves MSC coordinating with multiple base stations to maintain call quality.

1.10 Security and Identification in AMPS

• Identification Numbers:

  • ESN: Electronic Serial Number provided by manufacturers.

  • SID: System Identification Number for cellular systems.

  • MIN: Mobile Identification Number tied to the subscriber's phone number.

2G Cellular Systems

• Introduction of Digital Networks: Major transformation of mobile communications starting in 1987 with GSM.

• Involvement of various systems (TDMA, CDMA, PDC) across different regions.

• Role of GSM: Supported transition from luxury to necessity, leading to wider adoption and lower costs.

3G Cellular Systems

• Developed in the late 1990s to improve data capabilities, aimed at providing higher speed internet access and better call quality.

• Standards like UMTS (Wideband CDMA) and cdma2000 support enhanced speeds and capabilities.

4G Cellular Systems and Beyond

• While marketed as 4G, many existing networks operate on 3G technologies. Future goals include LTE-A achieving data rates up to 1 Gb/s.