Chapter 8: Wireless, Mobile Computing, and Mobile Commerce

Three Wireless Transmission Media

• Microwave: Line-of-sight wireless transmission medium carrying high-volume signals using high-frequency radio signals.

• Satellite: High-altitude wireless transmission that relays signals over vast areas.

• Radio: Uses radio wave frequencies to transmit data through the air without line-of-sight constraints.

Microwave vs. Satellite Communication

Three types of satellites

1. GEO (Geostationary Earth Orbit): Furthest from Earth (22,30022,300 miles). Stationary relative to Earth. Best for TV broadcasting.

2. MEO (Medium Earth Orbit): Mid-altitude (6,0006,000–12,00012,000 miles). Used primarily for GPS system coverage.

3. LEO (Low Earth Orbit): Closest to Earth (400400–1,0001,000 miles). Offers lowest delay; used for global satellite internet constellations (e.g., Starlink).

What are GPS used for and how do they work?

• GPS (Global Positioning System): Uses a constellation of MEO satellites to determine the exact location (latitude, longitude, elevation) of a receiver anywhere on Earth.

• How it works: A GPS receiver calculates its distance from at least 4 satellites simultaneously using time signals to pinpoint exact coordinates.

Short-Range Wireless Networks

• Bluetooth: Used to connect devices within short ranges (~30 feet).

• UWB (Ultra-Wideband): High-bandwidth short-range radio media used for precise spatial tracking.

• NFC (Near Field Communication): Smallest range (inches). Used for contactless mobile payment systems (e.g., Apple Pay).

Medium Range Wireless Networks

• Wi-Fi (Wireless Fidelity): High-speed wireless local network (WLAN) connecting devices to a local access point.

• Wi-Fi Direct: Enables direct device-to-device connection without requiring a wireless router.

Wide Area Wireless Networks

• Cellular Networks: Wireless networks divided into geographic cells served by base stations.

• WiMAX: Fixed wide-area broadband standard providing long-range wireless access.

What is CDMA and GSM?

Both are historical cellular transmission technologies:

• CDMA (Code Division Multiple Access): Used by network providers like Verizon and Sprint (did not require SIM cards).

• GSM (Global System for Mobile Communications): Used globally and by AT&T/T-Mobile (required SIM cards).

Technologies Used by Cellular Companies Today

• 4G / LTE (Long-Term Evolution): High-speed mobile data supporting video streaming and internet browsing.

• 5G: Current cellular standard featuring massive data throughput, near-zero latency, and support for widespread IoT connectivity.

What's M-Commerce and what's driving its growth?

M-Commerce (Mobile Commerce): Electronic commerce transactions conducted using mobile devices.

Drivers of growth: Ubiquity of smartphones, improved mobile internet networks (5G), convenience, mobile wallet adoption, location-based features.

Popular Mobile Commerce Applications

• Location-Based Services: Navigation, localized ads, finding nearby restaurants.

• Mobile Banking & Wallets: Checking balances, Venmo, Apple Pay, Google Wallet.

• On-Demand Services: Uber, Lyft, DoorDash.

Mobile Portal

Aggregated web portal customized for mobile displays

Wireless sensors

Distributed devices monitoring physical or environmental conditions (e.g., temperature, pressure)

RFID (Radio-Frequency Identification)

Uses microchips and antennas attached to items to track them wirelessly via radio waves (common in inventory management)

Categories of IoT

1. Consumer IoT: Devices used by individuals (e.g., smart thermostats, fitness trackers, smart home speakers).

2. Industrial IoT (IIoT): Connected systems used in commercial industries (e.g., supply chain tracking sensors, automated factory machinery).

Wireless Security Threats

• Rogue Access Point: An unauthorized access point installed on a network (or a fake "Evil Twin" Wi-Fi network) setup to intercept data.

• War Driving: Driving around neighborhoods searching for open, unprotected Wi-Fi networks.

• Eavesdropping: Unauthorized interception of private communication signals over wireless channels.

• Radio-Jamming: Intentional interference that blocks radio or wireless communications.