Q1.

Describe applications of GSM and GPRS

✅ Paragraph:

GSM enables mobile voice and SMS communication, while GPRS adds packet-switched data
for internet access. Together, they support a range of mobile services from voice to real-time
applications in sectors like healthcare, logistics, and e-commerce.

🔍 20+ Bullet Points:

1. Voice calls
2. SMS
3. Roaming services
4. Internet browsing (GPRS)
5. MMS (GPRS)
6. Email access
7. Mobile banking
8. Location tracking
9. Telemedicine
10. Agriculture data updates
11. Home automation
12. Fleet management
13. Mobile gaming
14. Real-time weather
15. Live traffic updates
16. Online payments
17. Social media
18. Industrial telemetry
19. Emergency alerts
20. IoT device communication
21. Remote monitoring

Q2. Draw and explain the frame structure of GSM

✅ Paragraph:

GSM uses a hierarchical frame structure to manage time-division multiplexing. The base
structure includes time slots grouped into frames, multiframes, superframes, and
hyperframes. Each level helps synchronize communication and manage logical channels.

🔍 20+ Bullet Points:

1. 1 frame = 8 time slots

2. Frame duration = 4.615 ms
3. 26-frame multiframe for traffic channels
4. 51-frame multiframe for control channels
5. Superframe = 51 or 26 multiframes
6. Hyperframe = 2048 superframes
 7. Used for encryption sync
8. TDMA structure
9. Supports logical channel mapping
10. Dedicated control and traffic frames
11. Frame number used for handovers
12. FCCH/ SCH frame usage
13. Slot allocation ensures QoS
14. Hierarchical structure aids in decoding
15. Synchronization of uplink/downlink
16. Sleep modes aligned with frames
17. Handover timing based on frame count
18. Packet scheduling possible
19. Used in frequency hopping
20. Key for call timing
21. Time slot = 577 μs

Q3. Explain the logical channels of GSM and GPRS

✅ Paragraph:

Logical channels in GSM and GPRS organize data transmission into control and traffic-
related categories. GSM includes channels for signaling, synchronization, and data, while
GPRS adds packet-specific channels for efficient IP data routing.

🔍 20+ Bullet Points:

1. Broadcast Channels (BCH)

2. Common Control Channels (CCCH)
3. Dedicated Control Channels (DCCH)
4. Traffic Channels (TCH)
5. Standalone Dedicated Control Channel (SDCCH)
6. Paging Channel (PCH)
7. Access Grant Channel (AGCH)
8. Random Access Channel (RACH)
9. Synchronization Channel (SCH)
10. Frequency Correction Channel (FCCH)
11. Packet Data Traffic Channel (PDTCH)
12. Packet Associated Control Channel (PACCH)
13. Packet Broadcast Control Channel (PBCCH)
14. Packet Common Control Channel (PCCCH)
15. Packet Random Access Channel (PRACH)
16. Packet Access Grant Channel (PAGCH)
17. Uplink and downlink separation
18. Multiplexed over time slots
19. Dedicated and shared usage
20. Crucial for GPRS session management
21. Channel allocation ensures QoS
Q4. Draw and explain Bluetooth architecture with a layered diagram

✅ Paragraph:

Bluetooth architecture consists of a protocol stack organized into layers such as the Radio
layer, Baseband, L2CAP, and higher profiles. Devices communicate in a piconet with one
master and up to seven slaves. Layers ensure reliable short-range data exchange.

🔍 20+ Bullet Points:

1. Radio layer (physical transmission)

2. Baseband (packet formatting)
3. Link Manager Protocol (LMP)
4. Host Controller Interface (HCI)
5. Logical Link Control and Adaptation Protocol (L2CAP)
6. Service Discovery Protocol (SDP)
7. RFCOMM (serial emulation)
8. TCS-BIN (telephony control)
9. Audio/video control (AVCTP)
10. Audio/video distribution (A2DP)
11. Object exchange (OBEX)
12. Master-slave concept
13. Piconet formation
14. Scatternet possible with multiple piconets
15. 2.4 GHz ISM band
16. Frequency hopping spread spectrum
17. Low power consumption
18. Supports synchronous and asynchronous links
19. Secure pairing and encryption
20. Used in IoT, wireless headsets, health devices
21. Short-range (10m–100m)

Q5. Explain design challenges in MANET

✅ Paragraph:

Mobile Ad-hoc Networks (MANETs) are self-organizing and infrastructure-less. Key

challenges include dynamic topology, limited bandwidth, energy constraints, and security
threats due to the open medium and decentralized control.

🔍 20+ Bullet Points:

1. Dynamic topology
2. Node mobility
3. Frequent route changes
4. Bandwidth limitation
 5. Power constraints
6. Limited physical security
7. Hidden terminal problem
8. Routing overhead
9. Scalability issues
10. Quality of Service (QoS) assurance
11. Link breakages
12. Network partitioning
13. Congestion control
14. Efficient broadcasting
15. Medium access control
16. Interference management
17. Multi-hop communication complexity
18. Addressing and naming
19. Real-time data delivery
20. Cross-layer design challenges
21. Data integrity and authentication

Q6. Services of GPRS and GSM

✅ Detailed Paragraph:

GSM (Global System for Mobile Communications) primarily provides voice communication,
SMS, and limited data services using circuit-switched technology. It revolutionized mobile
communication by enabling reliable and secure voice calling with global roaming. GPRS
(General Packet Radio Service), on the other hand, is an extension of GSM that introduces
packet-switched data transmission, enabling always-on connectivity and more efficient use of
network resources. GPRS supports services like mobile internet, email, MMS, and other IP-
based services. The integration of GPRS with GSM allowed mobile networks to support both
voice and data simultaneously, thus paving the way for advanced applications such as mobile
banking, real-time tracking, and the early phases of mobile IoT. These services together cater
to both consumer and enterprise needs in diverse areas including communication, commerce,
health, and education.

🔍 20+ Bullet Points:

1. Voice calls over circuit-switched GSM network

2. Short Message Service (SMS) support
3. General Packet Radio Service (GPRS) for mobile data
4. Multimedia Messaging Service (MMS) over GPRS
5. Always-on internet access with GPRS
6. Email services via mobile devices
7. WAP (Wireless Application Protocol) browsing
8. Access to online portals and intranets
9. Real-time location-based services (LBS)
10. Secure mobile banking services
11. Emergency services (e.g., 112 support)
 12. Network services like call forwarding, barring
13. Prepaid and postpaid billing integration
14. Roaming services with global interoperability
15. Real-time application support (chat, navigation)
16. IoT/M2M communication enabled via GPRS
17. Weather and news updates
18. Stock trading and market alerts
19. Interactive gaming and entertainment
20. Access to cloud services (limited)
21. Telemedicine and remote health monitoring

Q7. Features of CDMA2000 and IMT-2000 Technology

✅ Detailed Paragraph:

CDMA2000 is a 3G technology that enhances CDMA (Code Division Multiple Access) with
improved data rates, greater spectral efficiency, and the ability to support multiple services
simultaneously. It includes standards like 1xRTT and EV-DO (Evolution-Data Optimized),
which offer scalable bandwidths and improved data handling. IMT-2000, developed by the
ITU, is a global framework for third-generation (3G) mobile systems and encompasses
various technologies including CDMA2000, WCDMA (used in UMTS), and TD-SCDMA. It
aims to ensure global compatibility, high data rates (up to 2 Mbps), and seamless roaming.
Both CDMA2000 and IMT-2000 emphasize enhanced multimedia support, real-time
applications, and mobile broadband capabilities while being backward compatible with
existing 2G systems.

🔍 20+ Bullet Points:

1. CDMA2000 is based on spread spectrum technology

2. IMT-2000 is a global 3G standard defined by ITU
3. CDMA2000 1x supports both voice and data
4. EV-DO enables high-speed mobile internet
5. Spectral efficiency is significantly improved
6. Compatible with IS-95 networks
7. Scalable bandwidth from 1.25 to 5 MHz
8. Soft handoff reduces dropped calls
9. Strong power control mechanisms
10. Supports packet and circuit switched services
11. Integrated voice and data capabilities
12. Global roaming supported in IMT-2000
13. Multimedia services (video, VoIP, streaming)
14. Quality of Service (QoS) management
15. Lower latency than earlier technologies
16. Secure mobile data encryption
17. Multiple carrier and antenna support
18. Compatible with satellite systems
19. Supports 3G data speeds up to 2 Mbps
20. Seamless IP network integration
 21. Used as a base for further 4G evolution

Q8. Define Line Coding Techniques

✅ Detailed Paragraph:

Line coding refers to the process of converting digital data into digital signals that can be
efficiently transmitted over a communication medium. It involves assigning specific voltage
levels or waveforms to binary digits (0s and 1s). There are various line coding schemes
categorized into Unipolar, Polar, and Bipolar methods, each with their advantages and trade-
offs. Unipolar methods use one voltage level for binary 1 and zero voltage for binary 0. Polar
methods use positive and negative voltages to represent binary digits. Bipolar encoding
alternates positive and negative voltages for binary 1s, maintaining zero volts for 0s, which
reduces the DC component. Self-clocking schemes like Manchester and Differential
Manchester include transitions within the bit period, aiding synchronization. Proper line
coding ensures signal integrity, synchronization, and better error detection capabilities during
transmission.

🔍 20+ Bullet Points:

1. Converts binary data to transmittable signal

2. Used in digital communication systems
3. Unipolar NRZ: single voltage level for 1
4. Unipolar RZ: returns to zero within bit time
5. Polar NRZ: uses +V and -V for 1 and 0
6. Polar RZ: similar but returns to 0 halfway
7. Bipolar AMI: alternates voltage for 1s
8. Eliminates DC component with Bipolar
9. Manchester: transition at middle of bit
10. Differential Manchester: transition represents 0 or 1
11. Self-synchronizing codes
12. Better error detection properties
13. Suitable for clock recovery
14. Bandwidth efficiency varies by scheme
15. Trade-off between complexity and performance
16. Used in USB, Ethernet, optical systems
17. Ensures reliable transmission over channels
18. Helps identify long strings of same bits
19. Some codes require more bandwidth
20. Others are power efficient
21. Crucial for baseband transmission

Q9. Compare GSM vs UMTS w.r.t Packet Data, Quality Control, Frame
Length, Channel Bandwidth, etc.
 Feature GSM (2G/2.5G) UMTS (3G)
HSPA (max 42 Mbps)
Packet Data GPRS (max 171 kbps)
(rfwireless-world.com)
Sophisticated power control
Quality Control Basic power control
(rfwireless-world.com)
Frame Length 4.615 ms 10 ms (rfwireless-world.com)
Channel
200 kHz 5 MHz (rfwireless-world.com)
Bandwidth
W-CDMA (CDMA-based)
Technology TDMA/FDMA
(rfwireless-world.com)
9.6–14.4 kbps (circuit-switched); up to
Data Rate 384 kbps–2 Mbps (initial
171 kbps with GPRS)
4o

✅ Detailed Paragraph:

GSM (2G) is primarily a voice-centric circuit-switched technology that offers low-speed data
services, whereas UMTS (Universal Mobile Telecommunication System), a 3G technology,
supports both voice and high-speed packet data, allowing multimedia and internet services
with better performance. In GSM, the maximum data rate is up to 14.4 kbps per channel
using circuit switching, while UMTS offers speeds up to 2 Mbps using WCDMA and
supports simultaneous voice and data. UMTS also improves quality control through enhanced
error correction and radio resource management. The frame structure in GSM is rigid and
narrow, while UMTS uses a more flexible and longer frame with wider bandwidth (5 MHz vs
GSM’s 200 kHz), resulting in higher throughput and capacity. Overall, UMTS significantly
improves user experience for data-heavy applications.

🔍 20+ Comparison Points:

1. GSM uses circuit switching; UMTS uses both circuit and packet switching
2. GSM data rate ~14.4 kbps; UMTS up to 2 Mbps
3. GSM frame length: 4.615 ms; UMTS: 10 ms
4. GSM channel bandwidth: 200 kHz; UMTS: 5 MHz
5. UMTS uses WCDMA; GSM uses TDMA
6. GSM better for voice; UMTS for voice + data
7. UMTS supports multimedia services
8. UMTS enables high-speed internet
9. GSM has lower spectral efficiency
10. UMTS supports video calls
11. Handover in GSM is hard; UMTS offers soft handover
12. GSM has limited QoS; UMTS supports advanced QoS
13. UMTS supports simultaneous services (voice & data)
14. UMTS includes improved error correction
15. GSM more power efficient in idle mode
 16. UMTS more scalable and future-proof
17. GSM widely deployed; UMTS still evolving
18. UMTS has higher latency tolerance
19. GSM is more mature with global roaming
20. UMTS better suited for 3G apps
21. UMTS uses Node B instead of BTS

Q10. Different Types of Wireless Local Loop (WLL)

✅ Detailed Paragraph:

Wireless Local Loop (WLL) refers to the use of wireless technology to connect subscribers to
the public switched telephone network (PSTN) rather than traditional copper lines. It is used
in areas where installing wired infrastructure is costly or impractical. WLL systems are
particularly effective in rural or remote areas, temporary installations, or for rapid
deployment scenarios. There are various types of WLL technologies, including narrowband
and broadband WLL, based on the frequency and data rate support. Narrowband WLL
typically supports basic telephony, while broadband WLL provides high-speed internet
access. Furthermore, WLL can be classified by frequency band (e.g., 2.4 GHz, 5.8 GHz) and
duplexing methods (FDD, TDD). Technologies like DECT, CDMA, and WiMAX have been
used in WLL implementations. WLL offers advantages such as reduced deployment cost,
ease of maintenance, and scalability, making it suitable for developing regions.

🔍 20+ Bullet Points:

1. WLL provides last-mile wireless connectivity

2. Replaces traditional copper/fiber local loops
3. Supports voice and data services
4. Narrowband WLL: voice only
5. Broadband WLL: voice + high-speed data
6. Suitable for rural/remote areas
7. Used for rapid network deployment
8. DECT-based WLL used for voice
9. CDMA-based WLL for rural telephony
10. WiMAX-based WLL for high-speed internet
11. TDD and FDD duplexing methods
12. Licensed and unlicensed frequency options
13. Lower infrastructure costs than wired networks
14. Scalable for different subscriber densities
15. Easy relocation and maintenance
16. Less susceptible to theft and damage
17. Reduced installation time
18. Can coexist with mobile services
19. Useful for disaster recovery scenarios
20. Frequency bands include 2.4 GHz, 3.5 GHz, 5.8 GHz
21. Often used by telecom providers in developing countries

Q11. Explain GSM, GPRS, and UMTS architecture with a suitable diagram
GSM (Global System for Mobile Communications), GPRS (General Packet Radio
Service), and UMTS (Universal Mobile Telecommunications System) are successive
generations of cellular network architectures, each building on the other in terms of data
capabilities and efficiency.

GSM Architecture is structured around a core network and a radio access network. It
consists of:

1. Mobile Station (MS): The user’s device (mobile phone) and the SIM card.
2. Base Station Subsystem (BSS): Includes Base Transceiver Station (BTS) and Base
Station Controller (BSC).
3. Network Switching Subsystem (NSS): Contains the Mobile Switching Center
(MSC), Visitor Location Register (VLR), Home Location Register (HLR),
Authentication Center (AuC), and Equipment Identity Register (EIR).
4. Operation and Support System (OSS): Manages network operations and
maintenance.
5. GSM uses circuit-switched technology, best suited for voice communication.
6. It supports features like SMS, international roaming, and call forwarding.
7. Provides authentication and encryption for secure communication.

GPRS Architecture is an extension of GSM and provides packet-switched services,

enabling data transfer for services like internet browsing and multimedia messaging.

1. GPRS reuses the existing GSM architecture with additional nodes:

2. Serving GPRS Support Node (SGSN): Handles delivery of data packets to and from
mobile stations within its service area.
3. Gateway GPRS Support Node (GGSN): Connects the GPRS network to external IP
networks.
4. Packet Control Unit (PCU): Manages data transfer between BSS and SGSN.
5. GPRS offers always-on connectivity and efficient use of bandwidth.
6. It enables applications like email, WAP browsing, and instant messaging.
7. GPRS uses dynamic allocation of channels based on demand.

UMTS Architecture, based on W-CDMA, is a 3G technology that supports high-speed

multimedia services.

1. User Equipment (UE): Includes the mobile terminal and USIM card.
2. UMTS Terrestrial Radio Access Network (UTRAN): Composed of Node B
(similar to BTS) and Radio Network Controller (RNC).
3. Core Network: Comprises circuit-switched and packet-switched domains.
4. Circuit-switched includes MSC and GMSC for voice calls.
5. Packet-switched includes SGSN and GGSN (same as GPRS).
6. Supports seamless handovers between cells and networks.
7. Offers data rates up to 2 Mbps and low-latency services.
8. Supports voice, video calls, VoIP, and mobile TV.
9. Provides better QoS and mobility support than GPRS.
10. UMTS is the foundation for future 3G and 4G advancements.

A diagram typically shows:

 • Mobile Station → BTS → BSC → MSC/SGSN → GGSN → Internet
• For UMTS: UE → Node B → RNC → Core Network

Q12. Define Roaming in GPRS and GSM

Roaming in GSM and GPRS refers to the ability of a mobile subscriber to use services while
moving outside the geographical coverage of their home network and into a visited network.
Roaming can be classified into national (within the same country)
and international (between countries).

In GSM:

1. Roaming involves HLR, VLR, MSC, and AuC.

2. When a user enters a new area, the VLR updates the MSC.
3. MSC contacts the HLR in the home network to authenticate the subscriber.
4. After verification, call routing is managed via gateway MSC (GMSC).
5. The user can make/receive calls, SMS, and access services in the visited network.

In GPRS:

1. GPRS roaming requires support from SGSN and GGSN in both networks.
2. The SGSN in the visited network connects to the user.
3. The GGSN in the home network maintains IP connectivity.
4. The GGSN acts as the IP anchor, enabling session continuity.
5. GPRS roaming can be home-routed (via home GGSN) or local breakout (through
visited GGSN).
6. Authentication and charging are coordinated between operators.
7. Roaming agreements define access and billing terms.

Key Points:
8. Roaming allows seamless service access while traveling.
9. Ensures continuity of calls and data sessions.
10. Requires interoperability and trust between operators.
11. Involves network elements: HLR, VLR, SGSN, GGSN, MSC.
12. Roaming users often incur higher charges.
13. Allows global service coverage.
14. Supports both pre-paid and post-paid billing.
15. Roaming indicators may be displayed on the user’s handset.
16. In GPRS, dynamic IP allocation is handled during roaming.
17. Operators use protocols like MAP, GTP for roaming communication.
18. Security is ensured using encryption and authentication.
19. Roaming enhances user experience by removing geographical limits.
20. Enabled by global GSM/GPRS standards and agreements.

Q13. Define Line Coding Techniques

Line coding is the process of converting digital data into a digital signal suitable for
transmission over physical media. It determines how binary digits (0s and 1s) are represented
as electrical pulses or signals.

1. Line coding defines the voltage level, transition, and duration of each bit.
2. It helps in synchronization between transmitter and receiver.
3. Reduces DC bias and ensures error detection and bandwidth efficiency.
4. Categories include Unipolar, Polar, and Bipolar codes.

Common Line Coding Techniques:

5. Unipolar NRZ (Non-Return-to-Zero): 1 = positive voltage, 0 = zero voltage.
6. Unipolar RZ (Return-to-Zero): 1 = positive for half-bit, then 0; 0 = zero voltage.
7. Polar NRZ: 1 = positive voltage, 0 = negative voltage.
8. Polar RZ: 1 = positive for half-bit, 0 = negative for half-bit, returns to 0.
9. Manchester Encoding: Each bit has a transition at the center (1 = high-to-low, 0 = low-to-
high).
10. Differential Manchester: Transition at the beginning represents bit value.
11. Bipolar AMI: 1s alternate between positive and negative; 0 = zero voltage.
12. MLT-3: Three levels (positive, zero, negative); used in Ethernet.
13. 4B/5B and 8B/10B: Block coding for synchronization and DC balance.
14. Line coding affects bandwidth and signal integrity.
15. DC-free codes are important for transformer-coupled systems.
16. Synchronization codes prevent long strings of 0s or 1s.
17. Line coding is chosen based on channel characteristics.
18. It helps in error detection (some transitions indicate tampering).
19. Some line codes are self-clocking (e.g., Manchester).
20. It’s essential in wired networks like Ethernet and DSL.

Q14. Compare DM and PCM w.r.t. Bandwidth, Signaling Rate, Step Size, Bits
per Sample, Errors

Q14. Compare DM and PCM w.r.t Bandwidth, Signaling Rate, Step Size, No.
of Bits per Sample, Errors etc.

Feature PCM (Pulse Code Modulation) DM (Delta Modulation)

Converts analog signal into a Converts analog signal into a
Definition
series of coded binary pulses single-bit step-based stream
Bandwidth High (depends on number of bits
Lower than PCM
Requirement per sample)
High (because multiple bits per
Signaling Rate Lower (only 1 bit per sample)
sample)
Not fixed; determined by
Step Size Fixed step size
quantization levels
Number of Bits per Typically 8, 12, or more bits per
Only 1 bit per sample
Sample sample
Quantization Involves multi-level quantization Uses 1-bit quantizer (slope-based)
 Feature PCM (Pulse Code Modulation) DM (Delta Modulation)
Encoding
More complex Simpler
Complexity
Decoding
More complex Very simple
Complexity
Present but can be minimized with Present as slope overload or
Quantization Noise
more bits granular noise
Slope Overload
Not common Common if signal changes rapidly
Error
More likely in slowly varying
Granular Noise Less prominent
signals
Power Efficiency Less efficient due to more bits More power-efficient
Bandwidth
Lower due to high bit rate Higher due to fewer bits
Efficiency
Higher due to more bandwidth
Transmission Cost Lower
and bits
Feedback Needed for tracking the previous
Not needed
Requirement step
Telephony, audio, digital audio Low-speed voice communication,
Application
broadcasting speech coding
Suitability for
Highly suitable Suitable for low-rate speech
Speech
More flexible (can adjust number
Adaptability Limited by fixed step size
of levels)
Better (due to quantization and Lower (1-bit quantization leads to
Noise Immunity
coding) more error)
Compression Possible with adaptive PCM Possible with Adaptive DM
Support techniques (ADM)

Q15. Differentiate MANET vs WSN

MANET (Mobile Ad-Hoc

Feature WSN (Wireless Sensor Network)
Network)
General-purpose wireless Environmental or physical data
Primary Purpose
communication sensing and reporting
Nodes are generally stationary
Node Mobility Nodes are mobile
after deployment
High: Equipped with full Low: Limited CPU, memory,
Node Capability communication stack and energy, and communication
processing power capabilities
Power/Energy Less constrained compared to Highly energy-constrained; power-
Constraints WSN saving is critical
Lifetime is a critical factor; must
Network Lifetime Depends on mobility and usage
maximize battery life
 MANET (Mobile Ad-Hoc
Feature WSN (Wireless Sensor Network)
Network)
Many-to-many, all-to-all Many-to-one (converge-cast)
Traffic Pattern
communication toward a central sink node
Communication Typically unidirectional (from
Peer-to-peer, bidirectional
Type sensor to sink)
Environmental data like
Multimedia, voice, text, control
Data Type temperature, humidity, pressure,
messages
etc.
Deployment Spontaneous or on-the-fly (e.g., Often pre-planned, structured or
Method emergency networks) random in harsh environments
Node Density Lower than WSN High-density node deployment
LEACH, PEGASIS, TEEN,
Routing Protocols AODV, DSR, OLSR, TORA
Directed Diffusion
Moderate (tens to hundreds of High (hundreds to thousands of
Scalability
nodes) nodes)
Rare, unless nodes fail or deplete
Topology Changes Frequent due to node mobility
energy
Common, to reduce data
Data Aggregation Less frequent
transmission load
Quality of Service Focus on delay, throughput, and Focus on energy efficiency and
(QoS) connectivity timely delivery
Security High (due to open communication High but constrained due to limited
Requirements and mobility) node capabilities
Infrastructure
None None (but may use a sink/gateway)
Dependency
Hardware Laptops, smartphones, mobile Microcontroller-based sensor
Examples routers motes (e.g., MicaZ, TelosB)
Military, disaster recovery, Agriculture, environmental
Application Areas
vehicular networks monitoring, industrial automation
Lower, due to simplicity and mass
Cost per Node Higher
deployment

Q19. Define Sink and Source Nodes

In wireless communication networks, especially in Wireless Sensor Networks (WSNs), the

terms sink node and source node refer to specific roles that nodes play in the network's data
flow. A source node is a device or sensor that generates or collects data, typically from the
surrounding environment. These nodes detect physical parameters such as temperature,
humidity, motion, or pressure and then prepare this data for transmission. On the other hand,
a sink node, also known as a base station or gateway, is the node that receives, aggregates,
and processes the data sent by multiple source nodes. It often acts as the interface between
the sensor network and the external network or user.

1. Source nodes initiate communication by sensing the environment.

2. Sink nodes are data collection points that may relay data to external servers.
 3. Sink nodes are usually more powerful in terms of processing and energy.
4. Source nodes are deployed in large numbers across the monitoring area.
5. Sink nodes may perform data aggregation to minimize redundant transmissions.
6. A WSN typically has one or a few sink nodes and many source nodes.
7. Source nodes usually transmit small packets intermittently to conserve energy.
8. Sink nodes may initiate queries or requests to source nodes.
9. Sink nodes may be stationary or mobile depending on the application.
10. Mobile sinks help balance energy load across the network.
11. Source nodes may perform preprocessing to compress or clean data.
12. Sink nodes can execute algorithms for event detection or decision making.
13. In routing, sink nodes act as final destinations for multihop paths.
14. Source nodes often rely on multihop communication to reach the sink.
15. Sink nodes are crucial in determining network lifetime and efficiency.
16. Security threats differ: source nodes risk data tampering; sinks risk eavesdropping.
17. Sink nodes may be connected to the internet for remote monitoring.
18. Data collected at the sink is stored or visualized via dashboards or cloud systems.
19. Both types are essential: source for sensing, sink for coordination and control.
20. Together, they enable the core functionality of distributed sensing systems.

Q20. What are the Uses/Functions of WAP?

WAP (Wireless Application Protocol) is a suite of communication protocols that enables

mobile devices to access the internet and other network services. Developed during the early
mobile internet era, WAP addressed the limitations of mobile devices, such as small screens,
limited memory, and low processing power. It allowed devices like mobile phones and PDAs
to retrieve, interpret, and display web-based content tailored for their capabilities.

1. WAP enables mobile internet browsing on devices with limited resources.

2. It provides access to email services and news updates on the go.
3. Supports WML (Wireless Markup Language) for lightweight content rendering.
4. Enables mobile banking and online transaction services.
5. Facilitates location-based services using GPS integration.
6. Supports SMS-based content retrieval via WAP push services.
7. Allows access to enterprise intranets through WAP gateways.
8. Provides users with weather, sports, and news updates.
9. Assists in ticket booking, travel reservations, and e-commerce.
10. Used in mobile advertising and promotions via WAP-enabled messages.
11. Offers secure transactions with WTLS (Wireless Transport Layer Security).
12. Bridges wireless devices with web servers via WAP gateways.
13. Supports real-time chat and messaging applications.
14. Enables mobile content downloads (ringtones, wallpapers, apps).
15. Helps with IoT device configuration via WAP-compatible menus.
16. Offers a framework for interactive services in telecoms.
17. Can be used for remote access to email clients and file systems.
18. Reduces bandwidth usage with compact content.
19. Acts as a stepping stone to modern mobile web and app ecosystems.
20. Though largely obsolete now, WAP laid the groundwork for mobile internet
architecture.
Q21. Explain WSN, MANET, and IoT Architecture with a Neat Diagram

WSN (Wireless Sensor Network), MANET (Mobile Ad Hoc Network), and IoT (Internet
of Things) are three types of wireless architectures used for specific communication and
sensing purposes. While they differ in capabilities, all are decentralized and support real-time
interaction between devices.

WSN Architecture consists of:

1. Sensor nodes that detect data.

2. Sink node that aggregates data.
3. Communication module for wireless transmission.
4. Power source (usually battery).
5. Data is transmitted via single-hop or multi-hop routing.
6. Sink connects to a base station or cloud for analysis.
7. Often used in environmental monitoring, agriculture, and health.

MANET Architecture includes:

1. Mobile nodes that can move freely and act as routers.

2. Dynamic topology where links are formed on the fly.
3. Routing protocols like AODV, DSR handle packet delivery.
4. No fixed infrastructure—nodes rely on peer-to-peer communication.
5. Used in military, disaster zones, and vehicular networks.

IoT Architecture typically has three layers:

1. Perception layer: Sensors and actuators collect data (can include WSN).
2. Network layer: Transfers data over IP, Wi-Fi, LTE, or 5G.
3. Application layer: Provides services like smart homes, smart health.
4. Integrates cloud computing and big data analytics.
5. Devices communicate using MQTT, CoAP, HTTP.
6. Often employs AI for automated decision-making.
7. Ensures security via encryption and authentication.

Key Commonalities and Differences:

8. All use wireless communication and support distributed operation.
9. WSN is focused on sensing, MANET on communication, IoT on integration and
control.
10. WSN and MANET can be part of larger IoT systems.
11. IoT adds internet access and advanced analytics.
12. Power consumption is critical in WSN and IoT.
13. MANET and WSN are often ad hoc and autonomous.
14. IoT typically relies on cloud platforms for processing.
15. WSN and IoT are usually more structured than MANET.
16. IoT includes WSN and MANET as building blocks.
17. Security and interoperability are common challenges.
18. IoT emphasizes scalability, integrating billions of devices.
19. WSNs are sensor-centric; MANETs are user-centric.
20. Diagrams show layers: sensors → edge node → network → cloud/application.

Q22. Applications of RFID Technology

(Already covered in previous message – skip or request again if needed)

Q23. Compare ASK, FSK, PSK w.r.t Bandwidth, Noise Immunity,

Complexity, Error Probability, Bit Rate, Performance

ASK (Amplitude Shift Keying), FSK (Frequency Shift Keying), and PSK (Phase Shift
Keying) are digital modulation techniques used in wireless communication systems. Each has
distinct characteristics in terms of performance, bandwidth, and reliability.

1. ASK varies the amplitude of the carrier signal based on data bits.
2. FSK changes frequency to represent binary values (e.g., 0 = f₁, 1 = f₂).
3. PSK alters the phase of the carrier signal for data transmission.

Parameter ASK FSK PSK

Narrow (depends on order
Bandwidth Narrowest Wider than ASK
of PSK)
Low (amplitude High (phase is less noise-
Noise Immunity Better than ASK
affected easily) sensitive)
High (especially for
Complexity Very simple Moderate
higher-order PSK)
Higher in noisy
Bit Error Rate Lower than ASK Lowest among three
environments
Power Efficiency Low Moderate High
Wi-Fi, 4G, modern
Application Optical, RFID Radio, telemetry
comms
Modulation Type Amplitude Frequency Phase
Performance Poor in noise Moderate Excellent
Needed for coherent Essential for correct
Synchronization Not always needed
detection demodulation
Spectral Efficiency Low Moderate High
Multipath
Low Better than ASK Best
Resistance
Efficient (esp. in QPSK,
Energy Use Low Medium
BPSK)
Expensive (requires phase
Demodulator Cost Cheap Moderate
detection)
 4. ASK is used in RFID tags and infrared communication.
5. FSK is preferred for noise-prone environments.
6. PSK is used in broadband, satellite, and secure communications.
7. BPSK and QPSK are popular forms of PSK in 4G/5G.
8. FSK supports non-coherent detection; PSK usually needs coherent.
9. Overall, PSK offers the best tradeoff in performance vs complexity.
10. ASK is most susceptible to amplitude noise and fading.
11. Q24. Differentiate MANET vs Cellular Networks
12. MANET and Cellular Networks represent two opposite approaches to mobile
networking. MANETs are decentralized, while cellular networks are infrastructure-
based.

Feature MANET Cellular Network

Decentralized, infrastructure- Centralized, infrastructure-based
Architecture
less (towers, MSCs)
Each node acts as host and
Node Role Mobile nodes are only hosts
router
Managed by base stations and
Mobility Support High, self-organizing
handovers
Dynamic, ad hoc routing
Routing Fixed routing via MSCs
(AODV, DSR)
Coverage Limited by node range Wide area via cell towers
High, managed by operator
Scalability Low to moderate
infrastructure
Depends on node density and High, with redundancy in
Reliability
mobility infrastructure
QoS Management Poor to moderate Strong QoS support
Strong, with encryption, SIM auth,
Security Weak (due to decentralization)
etc.
Bandwidth
Shared among peers Allocated via central controller
Management
Power Consumption High (nodes route traffic) Lower (no routing role)
Setup Time Quick, on-the-fly Requires tower deployment
Military, disaster relief, Public communication (calls, 4G,
Use Cases
VANETs 5G)
Interference
Difficult Managed by operators
Handling
13.
14. Q25. List Advantages, Disadvantages, and Features of UMTS, W-
CDMA, CDMA, and CDMA-2000

Technology Features Advantages Disadvantages

3G system, uses W-CDMA, Global standard, good
High deployment cost,
UMTS supports voice & high-speed QoS, supports
requires new infra
data (up to 2 Mbps) multimedia
Technology Features Advantages Disadvantages
Complex receivers,
Wideband CDMA, 5 MHz High data rates,
W-CDMA interference management
channels, used in UMTS efficient spectrum use
needed
High capacity, soft
Code-based multiplexing, Code planning needed,
CDMA handoff, good
used in IS-95/2G more complex system
coverage
3G evolution of CDMA,
CDMA- Fast deployment, high Not globally adopted,
backward-compatible with IS-
2000 data rate, efficient fragmented spectrum
95