Financial crime, Motivations and (CY-803 (B)) Notes

UNIT 4: MOBILE & WIRELESS COMMUNICATION TECHNOLOGIES & SECURITY

1.0 FOUNDATIONAL WIRELESS NETWORK ARCHITECTURES & TYPES

1.1 Wireless Personal Area Network (WPAN)

Definition: A WPAN is a personal area network that uses wireless technology for communication among devices within a very short range (typically < 10 meters) of a person.
Distinguishing Characteristics:
- Range: Very short (centimeters to ~10 meters).
- Power Consumption: Very low, enabling battery-powered operation.
- Topology: Typically supports star or peer-to-peer (piconet) configurations.
- Data Rate: Can be low to moderate (e.g., Bluetooth ~1-3 Mbps, ZigBee ~250 kbps).
Comparison with Other Wireless Networks:

| Feature | WPAN | WLAN | WMAN | WWAN | | :--- | :--- | :--- | :--- | :--- | | Range | < 10 m | ~100 m | ~5-50 km | > 10 km | | Typical Use | Device interconnectivity | Local area networking | Metropolitan coverage | Cellular coverage | | Key Tech | Bluetooth, ZigBee | Wi-Fi (802.11) | WiMAX (802.16) | GSM, LTE, 5G | | Ownership | Personal | Private/Public | Service Provider | Service Provider |
Key Technologies:
- Bluetooth: Short-range, frequency-hopping spread spectrum (FHSS) in 2.4 GHz ISM band. Used for headsets, file transfer.
- ZigBee: Low-power, low-data-rate, based on IEEE 802.15.4. Used for IoT, home automation.
| IrDA: Infrared line-of-sight communication. Now largely obsolete.

[!TIP] Exam Focus: Expect a 7-mark question asking to define WPAN and contrast its range, power, and topology with WLAN/WWAN. Mention specific tech examples (Bluetooth vs. Wi-Fi).

1.2 Wireless Local Area Network (WLAN)

Definition: A WLAN is a local area network that uses wireless communication (typically radio waves) to connect devices within a limited area like a home, office, or campus.
Components:
- Access Point (AP): Central hub that connects wireless clients to the wired distribution system.
- Client/Station (STA): Device with a wireless network interface card (NIC).
- Distribution System (DS): The wired backbone (usually Ethernet) that interconnects APs.
Standards Evolution (IEEE 802.11 Family):

| Standard | Year | Frequency | Max Data Rate | Key Feature | | :--- | :--- | :--- | :--- | :--- | | 802.11b | 1999 | 2.4 GHz | 11 Mbps | First popular standard, DSSS | | 802.11a | 1999 | 5 GHz | 54 Mbps | OFDM, less interference | | 802.11g | 2003 | 2.4 GHz | 54 Mbps | OFDM, backward compatible with b | | 802.11n (Wi-Fi 4)| 2009 | 2.4/5 GHz | 600 Mbps | MIMO, channel bonding | | 802.11ac (Wi-Fi 5)| 2013 | 5 GHz | ~3.5 Gbps | MU-MIMO, wider channels | | 802.11ax (Wi-Fi 6/6E)| 2019 | 2.4/5/6 GHz | ~9.6 Gbps | OFDMA, improved MU-MIMO |
Architecture Modes:
- Infrastructure Mode: Clients communicate via an AP. Provides central management, internet access, and scalability.
- Ad-hoc/IBSS (Independent Basic Service Set): Peer-to-peer network without an AP. Used for direct device-to-device communication (e.g., file sharing).

[!TIP] Exam Focus: High-frequency short-note topic. Be prepared to list standards chronologically with their key improvements (MIMO, OFDMA, frequency bands). Know the difference between Infrastructure and Ad-hoc modes.

1.3 Wireless Metropolitan Area Network (WMAN) - WiMAX

Definition: WiMAX (Worldwide Interoperability for Microwave Access) is a family of IEEE 802.16 standards providing wireless broadband access over metropolitan areas.
Physical Layer (PHY) Structure & Operation:
- Uses Orthogonal Frequency Division Multiplexing (OFDM) for the downlink (base station to subscriber).
- Uses Orthogonal Frequency Division Multiple Access (OFDMA) for the uplink (subscriber to base station) to support multiple users efficiently.
- Supports both Time Division Duplex (TDD) and Frequency Division Duplex (FDD).
Frequency Bands:
- Originally licensed bands: 2-11 GHz (line-of-sight), 10-66 GHz (non-line-of-sight).
- Later standards (802.16e/m) support 2.3, 2.5, 3.5, and 5.8 GHz bands for mobile use.

[!TIP] Exam Focus: Direct question on WiMAX PHY. Must mention OFDM (downlink) and OFDMA (uplink) and their purpose (efficiency, multipath resistance).

1.4 Wireless Wide Area Network (WWAN) / Cellular Networks

Generational Evolution:
- 2G (GSM): Digital voice, SMS. Circuit-switched data (CSD).
- 2.5G (GPRS): Introduced packet-switched domain. "Always-on" data.
- 3G (UMTS): Mobile broadband, video calling, higher data rates (~2 Mbps).
- 4G (LTE): All-IP, high throughput (100+ Mbps mobile), low latency.
- 5G: Enhanced mobile broadband (eMBB), ultra-reliable low latency (URLLC), massive IoT.
3G vs. 4G Comparison:

| Parameter | 3G (UMTS) | 4G (LTE) | | :--- | :--- | :--- | | Architecture | Circuit-switched core + packet core | All-IP, flat architecture | | Data Rate | Up to ~2 Mbps (mobile) | 100+ Mbps (mobile), 1 Gbps (fixed) | | Latency | ~100-500 ms | < 50 ms (target < 10 ms) | | Spectrum | Dedicated licensed bands | Flexible bandwidth (1.4 to 20 MHz) | | Key Tech | WCDMA, CDMA2000 | OFDMA (downlink), SC-FDMA (uplink) | | Efficiency | Moderate | High spectral efficiency |

[!TIP] Exam Focus: High-frequency comparison question. Structure answer around Architecture (CS vs. All-IP), Data Rates, Latency, and Air Interface (WCDMA vs. OFDMA).

2.0 CELLULAR & MOBILE COMMUNICATION TECHNOLOGIES

2.1 Second Generation (2G) & 2.5G - GPRS

GPRS (General Packet Radio Service):
- Key Features & Capabilities:
  - Introduced a packet-switched (PS) domain alongside the existing circuit-switched (CS) domain.
  - Enabled "always-on" connectivity without call setup time for data sessions.
  - Higher data rates than CSD (theoretical ~171 kbps, practical ~40-50 kbps).
  - Charging based on data volume rather than connection time.
- Role in Enabling Mobile Data: It was the first true mobile internet technology, enabling services like mobile email (push), basic web browsing (WAP), and instant messaging on mobile phones, paving the way for smartphones.

[!TIP] Exam Focus: Distinguish GPRS from basic 2G by emphasizing packet-switching, always-on, and volume-based billing.

2.2 Third Generation (3G) - UMTS

UMTS (Universal Mobile Telecommunication System):
- Architecture:
  - UTRAN (UMTS Terrestrial Radio Access Network): Contains Node B (base station) and RNC (Radio Network Controller).
  - Core Network (CN): Evolved from GSM core, includes MSC (circuit-switched), SGSN/SGGSN (packet-switched).
- Key Features:
  - Higher data rates (up to 2 Mbps for stationary, 384 kbps for mobile).
  - Support for multimedia services (video calling, mobile TV).
  - Global roaming capabilities.
  - Improved spectral efficiency over 2G.

[!TIP] Exam Focus: High-frequency short-note topic. Know the two main architectural components: UTRAN (radio) and Core Network (MSC/SGSN). Link higher data rates to multimedia.

2.3 Fourth Generation (4G) & LTE

LTE (Long-Term Evolution):
- Key Features:
  - All-IP Network: Eliminates circuit-switched domain. Voice is VoIP (VoLTE).
  - Flat Architecture: Removes RNC, simplifies to eNodeB (base station) connected directly to core (EPC). Reduces latency.
  - High Throughput & Low Latency: Peak downlink ~300 Mbps (single antenna), < 50 ms latency.
  - Scalable Bandwidth: Supports 1.4, 3, 5, 10, 15, 20 MHz channels.
  - Advanced Air Interface: OFDMA (downlink), SC-FDMA (uplink). MIMO support.
- Benefits over 3G:
  - ~10x higher data rates.
  - Significantly lower latency (better for real-time apps, gaming).
  - Simpler, flatter network (lower operational cost).
  - Better spectral efficiency and user fairness (OFDMA).

[!TIP] Exam Focus: Highest-frequency topic after WLAN. Structure answer around All-IP, Flat Architecture, OFDMA/SC-FDMA, Throughput/Latency gains. Contrast directly with 3G's CS core and WCDMA.

3.0 NETWORKING PROTOCOLS & MECHANISMS FOR MOBILITY

3.1 Mobility Management: Mobile IP

Core Concepts (Both MIPv4 & MIPv6):
- Home Agent (HA): Router in the mobile node's home network that tracks its current location.
- Foreign Agent (FA - MIPv4 only): Router in the visited network that provides routing services.
- Care-of Address (CoA): Temporary IP address used by the mobile node in the foreign network. Can be foreign agent CoA (FA's address) or co-located CoA (temporary address assigned to MN).
- Tunneling: HA tunnels packets to the MN's CoA.
Mobile IPv4 vs. Mobile IPv6:

| Feature | Mobile IPv4 | Mobile IPv6 | | :--- | :--- | :--- | | Address Space | IPv4 (32-bit, scarce) | IPv6 (128-bit, abundant) | | Foreign Agent | Required (optional in some modes) | Not required (MN gets CoA via SLAAC/DHCPv6) | | Tunneling | IP-in-IP (RFC 2003) or Minimal Encapsulation | IPv6-in-IPv6 (native) | | Route Optimization | Possible but complex (via Binding Updates) | Built-in (via Binding Updates to Correspondent Node) | | Security | IPsec optional, often deployed manually | IPsec mandatory (but often not enforced in practice) | | Header Overhead | Significant (new IP header) | Minimal (extension headers) |

[!TIP] Exam Focus: Direct comparison question. Use a table. Key differentiators: FA requirement, tunneling type, route optimization ease, and IPsec integration.

3.2 Routing in Dynamic Wireless Networks

Ad Hoc Networks & Mesh Networks: Self-configuring, infrastructure-less networks where nodes act as routers.
Routing Protocol Classifications:

| Class | Principle | Examples | Pros | Cons | | :--- | :--- | :--- | :--- | :--- | | Proactive (Table-Driven) | Maintains routes to all nodes constantly. | DSDV, OLSR | Low latency for route discovery | High overhead in large networks | | Reactive (On-Demand) | Finds route only when needed (route discovery). | AODV, DSR | Low overhead in low-mobility | High latency on route discovery | | Hybrid | Combines both; proactive in local zone, reactive globally. | ZRP | Balances overhead & latency | Complex configuration |
Multi-hop Relay in Mesh Networks:
- Concept: Data is forwarded from source to destination via multiple intermediate nodes (hops) that act as relays/routers.
- Significance:
  1. Extended Coverage: Reaches beyond single-hop radio range.
  2. Improved Reliability & Redundancy: Multiple paths exist; if one node fails, traffic can reroute.
  3. Self-Healing & Self-Configuration: Network adapts to node addition/failure automatically.
  4. Cost-Effective Deployment: Reduces need for many fixed infrastructure points.

[!TIP] Exam Focus: For routing protocols, know one example of each class and their core trade-off (overhead vs. latency). For multi-hop relay, list at least 3 key significances (coverage, reliability, self-healing).

3.3 Transport Layer Considerations - TCP over Wireless

Challenges in Wireless Environment:
- High Bit Error Rates (BER): Causes packet loss, triggering TCP's congestion control (misinterpreted as congestion).
- Large Latency & Variable Delay (Jitter): Affects ACK timing and RTT estimation.
- Frequent Handoffs: Temporary loss of connectivity during movement between cells/APs.
- Asymmetric Links: Downlink often has much higher bandwidth than uplink.
Standard TCP Inefficiencies:
- TCP interprets all packet loss as network congestion, leading to unnecessary window size reduction (slow start, congestion avoidance).
- This results in severely degraded throughput in lossy wireless links, even when the wired backbone is uncongested.
Solutions (Brief): TCP variants like TCP-Westwood, TCP-Vegas, or link-layer solutions (e.g., Snoop proxy in WLANs) that distinguish between congestion loss and wireless error loss.

[!TIP] Exam Focus: High-frequency short-note topic. Structure: 1) List 3-4 wireless challenges (BER, latency, handoff, asymmetry). 2) Explain how standard TCP's congestion response (window reduction) is mismatched to wireless error loss. 3) Conclude with throughput degradation.

4.0 ENABLING TECHNOLOGIES & PROTOCOL LAYERS

4.1 Radio Frequency Identification (RFID)

Definition & Components:
- Tag (Transponder): Contains microchip (stores ID/data) and antenna. Can be passive (no battery), active (battery-powered), or semi-passive.
- Reader (Interrogator): Emits RF signal, receives tag response. Contains antenna and RF module.
- Middleware: Software that processes raw tag data, filters, and integrates with backend applications (e.g., inventory system).
Principle of Operation (Coupling):
- Inductive Coupling (LF/HF): Magnetic field between reader and tag coils. Short range (cm). Used in access cards, animal tags.
- Capacitive Coupling: Electric field coupling. Very short range.
- Backscatter Coupling (UHF/SHF): Most common for long range. Reader emits RF; tag modulates (reflects) the signal back by changing its antenna impedance. Signal travels to reader.
Data Transmission (Tag to Reader):
- Frequency: LF (125-134 kHz), HF (13.56 MHz), UHF (860-960 MHz), SHF (2.45 GHz).
- Modulation: Typically ASK, PSK, or FSK.
- Anti-Collision: Protocols (ALOHA-based, tree-based) to prevent multiple tags from responding simultaneously. Essential for reading many tags at once.

[!TIP] Exam Focus: Direct question on principle. Must explain backscatter (for UHF) and inductive coupling (for HF). Mention anti-collision as a key practical challenge.

4.2 Internet Protocol (IP) Encapsulation & Structure

Purpose of Encapsulation Header: The IP header contains control information (source/dest IP, TTL, protocol type, etc.) that routers use to forward the packet across network boundaries and deliver it to the correct transport layer protocol (TCP/UDP) at the destination.
IPv4 vs. IPv6 Header Structure Comparison:

| Feature | IPv4 Header | IPv6 Header | | :--- | :--- | :--- | | Length | Variable (20-60 bytes) | Fixed (40 bytes) | | Address Size | 32-bit (4 bytes) | 128-bit (16 bytes) | | Header Fields | 12 fields + Options (optional) | 8 fields (simpler, no checksum) | | Fragmentation | Done by routers & source | Only by source (router-friendly) | | Key Fields | Version, IHL, Total Length, Identification, Flags, Fragment Offset, TTL, Protocol, Header Checksum, Source/Dest IP | Version, Traffic Class, Flow Label, Payload Length, Next Header, Hop Limit, Source/Dest IP | | Checksum | Header checksum present | No header checksum (reliability in lower layers) | | Options | Complex Options field | Extension headers (more flexible) |

[!TIP] Exam Focus: Direct comparison question. Use a table. Highlight fixed vs. variable length, address size, removal of header checksum, and introduction of Flow Label/Traffic Class.

5.0 APPLICATIONS & ELECTRONIC COMMERCE

5.1 E-commerce

Definition: The buying and selling of goods or services, and the transmission of funds or data, over an electronic network, primarily the internet.
Business Models:
- B2B (Business-to-Business): Transactions between businesses (e.g., manufacturer to retailer).
- B2C (Business-to-Consumer): Direct sales from businesses to consumers (e.g., Amazon).
- C2C (Consumer-to-Consumer): Transactions between consumers via a platform (e.g., eBay, Facebook Marketplace).
Transformation of Traditional Business:
1. Global Reach: Businesses can access worldwide markets 24/7.
2. Reduced Operational Costs: Lower need for physical stores, staff, inventory overhead.
3. New Marketing & Customer Engagement: Digital marketing, personalized recommendations, social media interaction.
4. Supply Chain Efficiency: Just-in-time inventory, automated ordering.
5. New Business Models: Subscription services, digital goods, on-demand platforms.
6. Consumer Empowerment: Easy price comparison, reviews, anytime shopping.

[!TIP] Exam Focus: Define e-commerce, list B2B, B2C, C2C. For transformation, list 4-5 concrete changes (global reach, cost reduction, new marketing, supply chain, new models).

5.2 Electronic Payment Systems

Definition: Systems that facilitate financial transactions electronically, without physical cash or checks.
Categories:
- Card-based: Credit/Debit cards (via payment gateways like Stripe, PayPal).
- Digital Wallets/E-wallets: Store payment info (e.g., Apple Pay, Google Pay, Paytm).
- Cryptocurrencies: Decentralized digital assets (e.g., Bitcoin, Ethereum) using blockchain.
- Bank Transfers: NEFT, RTGS, IMPS.
- Buy Now, Pay Later (BNPL): Short-term financing.
Facilitation Mechanism over Electronic Networks:
1. Authentication: Verifies user identity (PIN, biometrics, 2FA, digital certificates).
2. Encryption: Secures data in transit (SSL/TLS) to prevent eavesdropping.
3. Authorization: Checks if the payer has sufficient funds/credit and the transaction is valid (via banks/payment processors).
4. Settlement: The actual transfer of funds between financial institutions (often days later for cards, near-instant for some digital wallets/crypto).
5. Non-Repudiation: Digital signatures ensure parties cannot deny their involvement.

[!TIP] Exam Focus: Define and categorize. Explain facilitation by walking through a transaction's security steps: Authentication -> Encryption -> Authorization -> Settlement.

6.0 SECURITY CONSIDERATIONS IN WIRELESS & MOBILE CONTEXTS

6.1 Military Security Models

Primary Objectives (CIA Triad + Accountability):
1. Confidentiality: Prevent unauthorized disclosure of information.
2. Integrity: Prevent unauthorized modification of information.
3. Availability: Ensure information and resources are accessible when needed.
4. Accountability (Non-Repudiation): Ensure actions can be traced to responsible entities (audit trails).
Role of Hierarchical Command Structures:
- Enforces centralized policy definition and enforcement.
- Implements mandatory access control (MAC) where security labels (e.g., Top Secret, Secret) are assigned by a central authority based on need-to-know and clearance level.
- Creates a chain of command for security decisions, incident response, and audit.
- Ensures consistent security posture across all organizational units.

[!TIP] Exam Focus: List 4 objectives (CIA + Accountability). For hierarchical role, link it to centralized policy, MAC, need-to-know, and chain of command.

6.2 Network Attacks - Denial of Service (DoS)

Definition & Objective: An attack where the attacker aims to disrupt the availability of a service or network resource for legitimate users, typically by overwhelming it with malicious traffic or exploiting vulnerabilities.
Common Vectors in Wireless/Mobile Networks:
1. Jamming: Transmitting noise on the same frequency to obscure legitimate signals (physical layer attack). Common in WPANs/WLANs.
2. Resource Exhaustion: Flooding the network with connection requests (e.g., TCP SYN flood), authentication requests, or deauthentication frames (in Wi-Fi) to consume AP or server resources.
3. Battery Drain Attacks: Exploiting protocols to force a mobile device to perform energy-intensive operations (e.g., repeated cryptographic handshakes), draining its battery.
4. Routing Attacks (in Ad-hoc/Mesh): Blackhole (dropping packets), greyhole (selective dropping), or wormhole (tunneling packets to create false topology) to disrupt routing.

[!TIP] Exam Focus: High-frequency short-note topic. Define DoS (goal: availability). List 2-3 wireless-specific vectors (jamming, deauth frames, battery drain, routing attacks). Contrast with wired DoS if possible.