Wireless & Mobile Computing (CS-702 (C)) - Unit 5 Short Notes

How unit 5 is examined

This unit covers the constraints on mobile OS design, iOS and Android, and M-commerce with payments and security; the Commercial Mobile Operating Systems short note carries the most marks, then the 7-mark M-commerce questions.

Special Constraints & Requirements

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>A mobile OS must run on small, battery-powered, always-connected devices, so it is designed around scarce power, memory, processing and display rather than raw performance.</mark>

Key points.

1. Power is limited by the battery, so the OS must switch off idle radios, screen and CPU cores and schedule background work sparingly.
2. Memory and storage are small and there is no swap disk, so the OS kills background apps instead of paging them out.
3. Processors are slower than desktop ones, so the OS and its apps must be light and efficient.
4. The screen is small and touch-driven, so the user interface needs gestures, an on-screen keyboard and adaptive layouts.
5. Requirements are portability, real-time response for calls, constant connectivity (cellular, Wi-Fi, Bluetooth), security of personal data, and support for many hardware makers (heterogeneity).

Asked: [7 marks] (Dec 2024) What are the special constraints and requirements of operating systems of mobile devices?

Commercial Mobile Operating Systems

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">High weight</span>

Definition. <mark>A mobile operating system is system software that manages the hardware, memory, power, networking and applications of a smartphone or tablet and provides the touch interface and services on which apps run.</mark>

Key points.

1. Commercial mobile OSs are Android (Google, open source, Linux based), iOS (Apple, closed, Unix based), and the older Windows Phone, BlackBerry OS and Symbian.
2. A mobile OS is layered: kernel and drivers at the bottom, then libraries and runtime, an application framework, and apps on top.
3. It gives power management, touch and sensor handling, radio and connectivity management, and app sandboxing.
4. It offers an app store and an update mechanism through which software is distributed.
5. A Software Development Kit (SDK) is the bundle of compiler, libraries, APIs, emulator, debugger and documentation used to build apps for one OS (Xcode for iOS, Android SDK for Android).
6. Examples of use are calls, messaging, navigation, banking and mobile commerce apps.

Short notes (any three).

i) Mobile OS. Points 1-4 above; conclude with apps such as calls and payments.

ii) SDK. Point 5 above; it contains APIs, tools, emulator and sample code, and cuts development time.

iii) DSR (Dynamic Source Routing). DSR is an on-demand ad hoc routing protocol in which the source puts the whole route in each packet header. Route discovery floods a Route Request (RREQ) that collects the node addresses it passes; the destination returns a Route Reply (RREP) along the reversed route, and the source caches it. Route maintenance uses Route Error (RERR) when a link breaks. It needs no periodic updates, but headers grow with route length.

iv) TCP and UDP.

Pitfall: Writing only definitions for the short note loses marks; give one working or difference for each topic chosen.

Answer frame. Open with the definition of each of your three chosen topics; draw the RREQ/RREP route for DSR if you choose it, or the comparison table for TCP and UDP; develop each in 3-4 sentences; close with applications.

Asked: [14 marks] (Dec 2020) Write short notes (any three): i) Mobile Operating System ii) Software Development Kit iii) DSR iv) UDP and TCP

Software Development Kit: iOS

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>iPhone OS (iOS) is Apple's closed mobile OS, developed with the iOS SDK (Xcode, Swift or Objective-C, simulator) and built as four layers.</mark>

Key points.

1. Cocoa Touch is the top layer and gives the UI framework (UIKit), multitasking, touch and gesture handling, and push notifications.
2. The Media layer provides graphics, audio and video services such as Core Graphics, Core Animation, OpenGL ES and AV Foundation.
3. The Core Services layer provides fundamental services such as iCloud, networking, SQLite database, location and contacts.
4. The Core OS layer is the base: kernel, drivers, security, Bluetooth, sockets and power management.
5. Special mobile OS features are touch and gestures, sensors (GPS, accelerometer), power saving, constant connectivity, app sandboxing, and lightweight memory use unlike a desktop OS.

Asked: [7 marks] (Jun 2025) Explain in detail components of iPhone OS? List the special features of a Mobile OS.

Android etc.

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>Android is Google's open-source, Linux-kernel-based mobile OS whose stack has five layers, and apps are built with the Android SDK.</mark>

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Key points.

1. Features: open source, free, customisable, multitasking, rich notifications, Google Play store, and wide device support.
2. The Linux kernel manages drivers, memory, processes, power and security.
3. Native libraries (SQLite, WebKit, OpenGL ES, libc) and the Android Runtime (ART, replacing Dalvik) sit above it.
4. The application framework offers Activity, Content Provider and Notification managers, and Applications such as Phone and Browser run on top.
5. The SDK contains the Java/Kotlin APIs, emulator, ADB, debugger and Android Studio; versions run from Cupcake to recent releases.

Asked: [7 marks] (Jun 2025) Explain about Android OS, features, software stack, SDK and their layers.

MCommerce : Structure

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>M-commerce is buying, selling and paying for goods, services and information through wireless handheld devices such as mobile phones.</mark>

Key points.

1. The structure has four parts: the mobile device (client), the wireless network (GSM, 4G, Wi-Fi), the gateway or middleware, and the host server with the merchant's database and payment system.
2. A request flows from the device over the network and gateway to the web server and back.
3. Pros are ubiquity, convenience and personalised location-based service.
4. Cons are security risk, small screen and limited bandwidth.
5. Examples are mobile banking, ticket booking, and shopping apps.

Asked: [7 marks] (Dec 2020) Explain structure, Pros and Cons of M-commerce.

Pros & Cons

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Low weight</span>

Definition. <mark>M-commerce is the transaction of business through mobile devices, and in India its value lies in reaching users who have phones but no computers.</mark>

Asked: [7 marks] (Dec 2024) What is M commerce? Write its pros and cons in a developing country like India.

Mobile Payment System

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>A mobile payment system lets a customer pay for goods and services with a mobile device instead of cash or cards.</mark>

Key points.

1. Methods are mobile wallets (Paytm), UPI apps, SMS or USSD banking, NFC tap-to-pay and carrier billing.
2. Workflow: the customer starts payment, the app sends it to the payment gateway, the bank verifies it with a PIN or OTP, and both sides receive confirmation.
3. Security uses encryption, PIN, OTP and tokenisation; it is fast and cashless, but depends on network coverage.
4. M-commerce types are mobile shopping, banking and ticketing, and current trends are UPI, QR and contactless payment.

Asked: [7 marks] (Jun 2025) Write short notes: i) M commerce ii) Mobile payment system

Security Issues

<span style="display:inline-block;padding:.16em .6em;border:1.5px solid currentColor;border-radius:999px;font-size:.68em;font-weight:700;letter-spacing:.06em;text-transform:uppercase;opacity:.75">Not asked since 2022</span>

Definition. <mark>Mobile security issues are the threats to a device, its data and its transactions from malware, theft and insecure networks.</mark>

Key points.

1. Malware and malicious apps can steal data, so install apps only from trusted stores.
2. Loss or theft of a device exposes data, so use screen locks, encryption and remote wipe.
3. Insecure Wi-Fi allows eavesdropping and man-in-the-middle attacks, so use VPN and HTTPS.
4. Phishing, SIM swap and weak authentication endanger payments, so use OTP and two-factor login.

Last-minute revision

• A mobile OS manages power, memory, touch, connectivity and apps on constrained devices.
• Constraints: limited battery, memory, CPU and screen; no swap disk.
• An SDK is compiler, APIs, emulator, debugger and documentation for one OS.
• iOS layers, top to bottom: Cocoa Touch, Media, Core Services, Core OS.
• Android stack: Applications, Framework, Libraries and ART, Linux kernel.
• DSR: source routing with RREQ, RREP and RERR.
• TCP is reliable and connection-oriented; UDP is fast and connectionless.
• M-commerce is transactions through wireless handheld devices.
• M-commerce pros: ubiquity and convenience; cons: security, small screen, bandwidth.
• Mobile payment methods: wallet, UPI, NFC, SMS or USSD.

Memory hooks

• iOS layers: "Can Mice Chew Oats" (Cocoa Touch, Media, Core Services, Core OS).
• Android stack: "All Frogs Like Kites" (Apps, Framework, Libraries, Kernel).
• M-commerce cons: "S-S-B" (Security, Small screen, Bandwidth).
• DSR messages: Request, Reply, Error.

Coverage checklist

• Special Constraints & Requirements: Dec 2024 constraints question.
• Commercial Mobile Operating Systems: Dec 2020 short notes (Mobile OS, SDK, DSR, UDP and TCP).
• Software Development Kit: iOS: Jun 2025 iPhone OS components and mobile OS features.
• Android etc.: Jun 2025 Android OS, stack and SDK.
• MCommerce : Structure: Dec 2020 structure, pros and cons.
• Pros & Cons: Dec 2024 M-commerce in India.
• Mobile Payment System: Jun 2025 short notes on M-commerce and payment.
• Security Issues: no past question.