UNIT V - MOBILE COMMUNICATION

Electromagnetic Spectrum

The electromagnetic spectrum is a comprehensive range of electromagnetic radiation that encompasses various types of waves, including radio waves, microwaves, infrared radiation, visible light, ultraviolet light, X-rays, and gamma rays. These waves differ in their wavelength, frequency, and energy levels, and they are used in a wide range of applications, from radio broadcasting to medical imaging.

Radio Waves

Radio waves are a type of electromagnetic radiation with relatively long wavelengths and low frequencies. They are commonly used in radio communication, broadcasting, and wireless technologies. The range of radio frequencies is extensive, allowing for the transmission of data and information over long distances. Radio waves are integral to radio and television broadcasting, as well as wireless communication methods like Wi-Fi, Bluetooth, and cellular networks.

Mobile Phone

Mobile phones, or cell phones, have revolutionized communication by utilizing radio waves to connect users wirelessly. These devices have evolved from simple voice communication tools to multifunctional smartphones with internet access, multimedia capabilities, and a wide array of applications. The seamless integration of radio wave technology into mobile phones enables users to make calls, send messages, and access the internet from virtually anywhere.

Evolution of Mobile Phones

• The evolution of mobile phones spans several decades, with early devices primarily focused on voice calls. 
• Over time, they have transformed into powerful computing devices that provide internet access, navigation, gaming, and countless other features. 
• The introduction of smartphones, epitomized by the iPhone and Android devices, marked a turning point in the industry. 
• These devices offer touchscreens, app stores, high-quality cameras, and extensive connectivity options.

GSM vs. CDMA: A Comparison

GSM (Global System for Mobile Communications) and CDMA (Code Division Multiple Access) are two distinct cellular communication technologies that underlie many of the world's mobile networks. While both serve the same fundamental purpose of enabling wireless communication, they differ in terms of technology, network architecture, and subscriber management. 

Here's a detailed comparison of GSM and CDMA:

1. Technology:

    GSM: GSM is a time-division technology. It divides time into slots, and multiple users share the same frequency by using different time slots. This is known as Time Division Multiple Access (TDMA).

    CDMA: CDMA, on the other hand, uses spread-spectrum technology, where each user's data is spread over a wide bandwidth using a unique code. This is known as Code Division Multiple Access (CDMA).

2. Subscriber Identity:

    GSM: GSM uses SIM cards (Subscriber Identity Module) to identify subscribers. SIM cards can be easily removed and transferred between devices, making it convenient to switch phones.

    CDMA: CDMA does not use removable SIM cards for subscriber identification. Subscriber information is stored in the network, and devices are tied to the network. This makes device switching less straightforward.

3. Global Usage:

    GSM: GSM is widely used globally and is the dominant standard in most parts of the world, including Europe, Africa, and Asia.

    CDMA: CDMA is primarily used in the United States and a few other countries. It does not have the same level of international adoption as GSM.

4. Voice Quality:

    GSM: GSM generally provides good voice quality due to its time-division technology. Users often experience clearer and more consistent calls.

    CDMA: CDMA is also known for good voice quality. The spread-spectrum technology can provide better call quality in some conditions, especially in areas with signal interference.

5. Network Structure:

    GSM: GSM networks have a cellular structure with base stations (cell towers) that divide geographic regions into cells. Handovers between cells are well managed, making it suitable for high mobility scenarios.

    CDMA: CDMA networks do not have the same strict cell structure. CDMA devices communicate with all nearby cell towers simultaneously, which can provide advantages in terms of coverage and capacity.

6. Data and Internet:

    GSM: GSM networks have evolved to provide data services and internet connectivity. GPRS, EDGE, 3G, and 4G technologies are based on GSM.

    CDMA: CDMA networks also support data and internet services. CDMA2000 and EV-DO are CDMA-based technologies that offer high-speed data access.

7. Device Compatibility:

    GSM: GSM devices are generally more versatile in terms of compatibility. Unlocked GSM phones can be used with various carriers by switching SIM cards.

    CDMA: CDMA devices are often carrier-specific, making it more challenging to switch devices between carriers.

8. Roaming:

    GSM: GSM networks have better support for international roaming. With a GSM phone, users can often use their devices in multiple countries with minimal hassle.

    CDMA: CDMA devices may face challenges with international roaming due to the network's limited global presence.

Microwave Communication

Microwave communication is a technology that employs high-frequency radio waves, typically in the microwave range, to transmit data over long distances. It is the foundation of many long-distance communication systems and forms the backbone of mobile networks. Microwave communication technology relies on line-of-sight propagation and is known for its reliability in point-to-point connections.

Microwave vs. Radio Wave Comparison:

Microwaves and radio waves are both types of electromagnetic radiation, but they differ in terms of their properties, applications, and frequencies. 

Here is a comparison between microwaves and radio waves:

1. Frequency and Wavelength:

    Microwaves: Microwaves have shorter wavelengths and higher frequencies compared to radio waves. They typically have frequencies ranging from 1 gigahertz (GHz) to 300 gigahertz.

    Radio Waves: Radio waves have longer wavelengths and lower frequencies. They cover a broad range of frequencies, from kilohertz (kHz) used in AM radio to megahertz (MHz) for FM radio and television broadcasting.

2. Applications:

    Microwaves: Microwaves are commonly used in various technologies and applications, including microwave ovens, satellite communication, radar systems, and wireless communication (e.g., Wi-Fi and Bluetooth).

    Radio Waves: Radio waves are primarily used for radio broadcasting, television broadcasting, AM and FM radio, and some wireless communication standards like AM and FM radio receivers.

3. Penetration and Obstruction:

    Microwaves: Microwaves are less effective at penetrating obstacles, and they are absorbed by water and moisture, which is why they are used in microwave ovens for cooking and in satellite communication.

    Radio Waves: Radio waves have better penetration capabilities. They can pass through buildings and obstacles and are used in radio and television broadcasting, making it possible to receive signals indoors.

4. Energy and Power:

    Microwaves: Microwaves carry higher energy due to their higher frequency, making them suitable for various high-power applications, such as radar systems and microwave ovens.

    Radio Waves: Radio waves carry lower energy due to their lower frequency. This results in less potential for interference and safety concerns compared to microwaves.

5. Safety and Health Concerns:

    Microwaves: Microwaves can be hazardous if not properly controlled, as they can heat substances and cause tissue damage. Microwave ovens are designed with safety mechanisms to prevent exposure.

    Radio Waves: Radio waves are generally considered safe for human exposure. The energy levels are insufficient to cause harm, and safety standards are in place to regulate exposure in broadcasting and telecommunications.

Mobile Protocols and Networks

Mobile communication relies on a variety of protocols and networks to facilitate wireless connectivity. The transition from 2G to 3G, 4G, and 5G networks has brought significant advancements in data speed, capacity, and latency. Each generation offers distinct advantages, and the choice of network depends on factors like coverage, device compatibility, and user requirements.

iPhone

The iPhone, introduced by Apple Inc., played a pioneering role in the mobile industry. It revolutionized the concept of smartphones by introducing intuitive touchscreens, the App Store, and a user-friendly interface. iPhones have become synonymous with high-quality cameras, seamless software integration, and a wide array of applications that cater to various aspects of modern life.

Android 

Android is an open-source operating system developed by Google for mobile devices. It offers a versatile platform for numerous manufacturers to build smartphones and tablets. Android's flexibility and extensive app ecosystem have contributed to its widespread adoption and dominance in the mobile market. Android devices cater to a wide range of user preferences and budgets.

Block Diagram of an Android Phone:

1. Central Processing Unit (CPU): The CPU serves as the device's "brain," executing instructions and processing data.
2. Memory (RAM and Storage): Android phones feature RAM for temporary data storage and storage memory for apps, files, and data.
3. Display: The display screen shows the user interface, apps, and content.
4. Battery: The power source that provides energy for the device.
5. Camera: Both front and rear cameras for photography and video recording.
6. Sensors: Various sensors such as proximity, light, accelerometer, and gyroscope for user interaction and data collection.
7. Connectivity Interfaces: Including Wi-Fi, Bluetooth, and cellular radios for wireless communication.
8. Operating System (Android): The Android OS manages hardware and software interactions.
9. App Ecosystem: The Google Play Store for downloading and managing apps.
10. User Interface (UI): The graphical user interface through which users interact with the device and apps.
11. Audio Components: Such as speakers and microphones for voice calls and multimedia.
12. Charging Port: The interface for charging the device's battery.

Block Diagram of an iPhone:

1. Central Processing Unit (CPU): The iPhone's CPU is designed by Apple and is a core component.
2. Memory (RAM and Storage): iPhones include RAM and internal storage for apps and data.
3. Display: The iPhone's Retina display provides high-resolution visuals.
4. Battery: The internal battery powers the device.
5. Camera: iPhones feature high-quality front and rear cameras.
6. Sensors: Apple incorporates various sensors, including Face ID and the M-series motion coprocessor.
7. Connectivity Interfaces: Wi-Fi, Bluetooth, and cellular radios enable wireless communication.
8. Operating System (iOS): The iOS operating system is a key element of the device.
9. App Ecosystem: The App Store is Apple's platform for app distribution.
10. User Interface (UI): The iOS user interface is known for its simplicity and user-friendliness.
11. Audio Components: iPhones include high-quality speakers and microphones.
12.  Lightning Port: The charging and data transfer port for iPhones.

Applications

The applications of mobile phones are incredibly diverse, ranging from communication and entertainment to productivity and health. These devices have become integral to modern life, offering features like voice calls, text messaging, social media, web browsing, email, navigation, gaming, photography, and health tracking. Mobile apps cater to a wide spectrum of needs, making smartphones versatile tools for both personal and professional use. Mobile phones are not only communication devices but also multifunctional companions that enhance convenience and connectivity.