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Mobile Telephony ​

Mobile telephony refers to a wireless communication system that allows users to make voice calls, send text messages, and access data services through portable devices like mobile phones and tablets. It utilizes radio frequencies to connect devices without physical wires.

Definition and Key Features ​

Definition ​

Mobile telephony is a wireless communication system that enables users to make voice calls, send text messages, and access data services using portable devices such as mobile phones and tablets.

Key Features ​

  • Wireless Communication: Connects devices using radio frequencies, eliminating the need for physical wires.
  • Cellular Technology: Divides geographical areas into smaller regions called "cells," each served by a base station.
  • Portability: Users can move freely while maintaining a connection to the network.
  • Network Switching: Calls and data are seamlessly transferred between cells as the user moves (a process called "handoff" or "handover").
  • Real-Time Access: Enables instant voice calls, messaging, and internet usage.

Components of a Mobile Telephony System ​

Mobile communication relies on a cellular network structure, where the coverage area is divided into cells, typically hexagonal in shape. Each cell is served by a base station (also called BTS - Base Trans-receiver Station) that provides the signal and communicates with mobile devices within that cell.

  • Cell Towers (Base Stations): Responsible for covering a specific geographical area and facilitating communication with mobile devices in that area. They are connected in a grid to provide seamless coverage.
  • Mobile Devices (User Equipment): Include mobile phones, smartphones, and other portable communication devices that send and receive signals. A cell phone contains both a low-power transmitter and receiver and can use both simultaneously, understand different frequencies, and automatically switch between them.
  • Mobile Switching Centers (MSC): Central components that connect base stations to the core network, routing calls and data between base stations and external networks (like the PSTN or internet). They also manage handoffs.
  • Core Network: The backbone of the mobile telephony system, connecting all base stations and switching centers to external networks.
  • Backhaul Network: The infrastructure that connects base stations to the core network, typically via fiber optic cables or microwave links.

Signal Processing and Transmission Techniques ​

Modulation ​

The process of altering the characteristics of a high-frequency carrier wave (such as amplitude, frequency, or phase) in accordance with the baseband signal (information) for efficient transmission over long distances.

  • Amplitude Modulation (AM): Varies the amplitude of the carrier wave. Used in AM radio broadcasting.
  • Frequency Modulation (FM): Varies the frequency of the carrier wave. Used in FM radio broadcasting and TV transmission.
  • Phase Modulation (PM): Varies the phase of the carrier wave.
  • Quadrature Amplitude Modulation (QAM): Used in digital systems to transmit multiple bits per symbol.
  • Pulse Code Modulation (PCM): A digital modulation technique for pulsed carrier waves, where the signal is sampled, quantized, and transmitted as a binary code.

Multiplexing ​

Allows multiple users or signals to share the same frequency channel simultaneously.

  • Frequency Division Multiple Access (FDMA): Divides the available frequency spectrum into separate channels, with each user allocated a unique frequency slot during a call.
  • Time Division Multiple Access (TDMA): Allocates specific time slots for users to share the same frequency. This increased capacity compared to FDMA.
  • Code Division Multiple Access (CDMA): Allows multiple users to share the entire available spectrum simultaneously by encoding each user's information with a unique code. It is known for higher capacity and security.
  • Orthogonal Frequency Division Multiplexing (OFDM): An advanced technique that splits the frequency band into many smaller subcarriers, reducing interference and increasing data rates. Used in 4G and 5G.

Switching Techniques ​

Determine how connections are established and managed.

  • Circuit Switching: A dedicated communication path is established and maintained for the entire duration of the communication. Used primarily for voice calls in early mobile generations.
  • Packet Switching: Data is broken into smaller units called "packets" and sent individually over shared network paths. Bandwidth is shared dynamically, making it more efficient for data transmission. Used for data services in 3G, and for both voice and data in 4G and 5G.

Evolution of Mobile Telephony (Generations) ​

The evolution of mobile communication is categorized into generations, each bringing significant technological advancements.

1G (First Generation) - Analog Communication (1980s) ​

  • Technology: Analog signals. Operated on FDMA technology.
  • Features: Voice-only communication, poor voice quality, limited coverage, and high power consumption. Calls could be easily intercepted due to lack of security.
  • Speed: Approximately 2.4 kbps.
  • Global Impact: Enabled mobile communication but had poor quality and high costs.

2G (Second Generation) - Digital Communication (Early 1990s) ​

  • Technology: Digital voice (e.g., GSM). Introduced TDMA and CDMA techniques. GSM is SIM-based, while traditional CDMA was handset-based.
  • Features: SMS capabilities, better voice quality, lower power consumption, and enhanced security with digital encryption.
  • Speed: Approximately 64 kbps.
  • Global Impact: Made mobile phones affordable and widespread, expanding coverage.

2.5G (Bridging the Gap to 3G) (Late 1990s – Early 2000s) ​

  • Technology: Introduced GPRS (General Packet Radio Service) for internet access.
  • Features: Improved data speeds, enabling basic internet services like browsing and emails. Allowed for "Normal value added services" such as downloading wallpapers and ringtones.
  • Speed: 56-115 kbps.

2.75G ​

  • Technology: Introduced EDGE (Enhanced Data Rates for GSM Evolution) technology.
  • Speed: Increased up to 384 Kbps.

3G (Third Generation) - Mobile Internet Revolution (2000s) ​

  • Technology: Focused on data transmission using packet switching (while voice calls remained circuit switching). Operated on UMTS (Universal Mobile Telecommunication System) and WCDMA (Wideband CDMA).
  • Features: High-speed internet access, video calls, and multimedia services.
  • Speed: Up to 2 Mbps. HSPA (High-Speed Packet Access) further increased speed up to 100 Mbps.

4G (Fourth Generation) (2010s) ​

  • Technology: Uses packet switching for both data and voice calls (LTE - Long Term Evolution). Utilizes OFDM technique.
  • Features: High-speed internet, HD video streaming, and VoLTE. Higher bandwidth and lower latency.
  • Speed: Up to 1 Gbps.

5G (Fifth Generation) - Ultra-Connectivity (2020s) ​

  • Technology: Based on IEEE Std 802.11ac. Utilizes low-band, mid-band, and high-band (millimeter wave) spectrums.
  • Features: Ultra-fast internet, automation, IoT, AR/VR.
  • Speed: 1-10 Gbps. Offers minimal latency.
  • Uses: HD Video, HD games, Artificial intelligence, Internet of things.
  • Spectrum in India: Includes 3.3-3.6 GHz, 24.25-33.4 GHz, and 37-43.5 GHz.

Spectrum Usage in Mobile Telephony ​

The frequency spectrum is a critical, finite resource used for wireless communication. It is divided into various bands for different mobile network standards.

Spectrum Bands for Mobile Telephony ​

  • 2G (GSM/CDMA): 900 MHz, 1800 MHz. Used for voice calls and low-speed data.
  • 3G (UMTS): 850 MHz, 900 MHz, 1900 MHz, 2100 MHz. Used for voice calls, internet browsing, and video calls.
  • 4G (LTE): 700 MHz, 800 MHz, 1800 MHz, 2300 MHz, 2500 MHz. Used for high-speed internet, HD video streaming, and VoLTE.
  • 5G:
    • Low-Band: 600 MHz - 900 MHz (for better coverage, lower speed). Can cover long distances and penetrate buildings.
    • Mid-Band: 1 GHz - 6 GHz (balanced speed and coverage). Primary use for 4G and 5G in densely populated areas.
    • High-Band (mmWave): 24 GHz - 100 GHz (extremely fast speed, limited coverage area). Useful for high-density networks and large data transfers.

Spectrum in India ​

Mobile carriers in India utilize airwaves in bands like 800 MHz, 900 MHz, 1800 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Recent 5G auctions in 2022 included 3.3 GHz and 26 GHz bands.

Spectrum Allocation and Management in India ​

Spectrum is a limited and valuable resource.

Regulatory Bodies ​

  • Department of Telecommunications (DoT): Responsible for spectrum allocation and telecom policy formation in India. Issues licenses to telecom companies and conducts spectrum auctions.
  • Telecom Regulatory Authority of India (TRAI): Provides recommendations for spectrum pricing and usage. Monitors service quality and competition among telecom operators.
  • Wireless Planning & Coordination (WPC): Handles technical processes for spectrum planning and allocation, and monitors national and international spectrum usage.

Allocation Process ​

  • Spectrum Auction: Private telecom companies (e.g., Airtel, Jio, Vi, BSNL) participate in auctions to acquire spectrum, typically allocated for 20 years.
  • Administrative Allocation: Spectrum is directly allocated to government institutions, defense services, railways, and public broadcasting services (e.g., AIR, Doordarshan). Priority is given to defense and emergency services.

Recent Spectrum Auctions ​

The 2022 5G auction saw bids for 3.3 GHz and 26 GHz bands.

The future of mobile telephony is expected to be shaped by several emerging trends.

  • 6G Spectrum Preparation: India is planning for 6G research with spectrum bands above 100 GHz.
  • AI and Machine Learning Integration: AI and ML will become integral for improving user experience, network optimization, and security, leading to more advanced personal assistance and predictive services.
  • Augmented Reality (AR) and Virtual Reality (VR): With improved 5G bandwidth and lower latency, AR and VR are expected to become more prevalent, revolutionizing gaming, education, and remote work.
  • Advanced Security Protocols: Future mobile telephony will incorporate advanced encryption methods and biometric security features as threats evolve. Blockchain technology may also enhance security and privacy.
  • Sustainable and Green Technologies: Growing emphasis on eco-friendly materials and energy-efficient technologies, including efforts to reduce electronic waste and promote recycling.
  • Edge Computing: Data processing will move closer to the source to reduce latency and bandwidth usage, crucial for real-time applications like autonomous driving and industrial automation.
  • Flexible and Foldable Displays: Development of these screens is expected to continue, offering new form factors and user experiences in mobile devices.
  • Integration with Wearable Technology: Mobile phones will continue to integrate with smartwatches, fitness trackers, and AR glasses for seamless user experiences.
  • Advanced Network Services: 5G's network slicing allows operators to provide tailored services, and network-as-a-service (NaaS) models could change how businesses and consumers access mobile services.

Advantages of Mobile Telephony ​

  • Automation: Devices can operate without human intervention.
  • Data Analytics: Facilitates large-scale data collection and analysis.
  • Energy Efficiency: Smart systems can be used to save energy.
  • Security & Safety: Enhanced by smart cameras and home security systems.
  • Improved Healthcare Monitoring: AI-enabled health devices contribute to better health monitoring.
  • High Data Integrity: Less susceptible to noise.
  • Efficiency: Better use of bandwidth.
  • Security: Easier to encrypt and secure.

Difference Between Mobile and Fixed Telephony ​

  • Connectivity: Mobile telephony is wireless and portable, while fixed telephony is wired and location-specific.
  • Infrastructure: Mobile requires base stations, MSCs, and wireless links, whereas fixed requires physical cables and switching centers.
  • Mobility: Mobile users can move freely; fixed is restricted to the phone line location.
  • Applications: Mobile offers voice, SMS, internet, and multimedia; fixed primarily offers voice.

Relevant Policies and Acts ​

  • Telecommunications Act, 2023: Enacted on December 25, 2023, it replaces the Indian Telegraph Act, 1885, and the Indian Wireless Telegraphy Act, 1933. Its objective is to modernize and regulate telecommunication services in India. Key provisions include regulating OTT services, government powers over telecom equipment and services for national security, introducing auction-based spectrum allocation (with a focus on satellite broadband), establishing a framework for "Right of Way," and emphasizing consumer protection.
  • National Digital Communication Policy: Aims to attract $100 billion investment in the telecom sector, generate 40 lakh employment opportunities, provide 50 Mbps broadband connectivity to each person, and achieve 1Gbps connectivity for all Gram panchayats by 2020 (and up to 10 Gbps by 2022). It also includes constituting a National Fibre Authority and constructing a National Digital Grid, increasing digital communication's GDP contribution from 6% to 8%, and aiming to include India among the top 50 countries in the ICT Development Index.