Question 1(a) [3 marks]

Differentiate Basic modes of Communication: Broad casting communication and Point to Point Communication.

Answer:

Parameter	Broadcasting Communication	Point to Point Communication
Definition	One transmitter sends signals to multiple receivers simultaneously	One transmitter communicates with one specific receiver
Direction	Unidirectional (one-way)	Bidirectional (two-way)
Examples	TV, Radio, FM	Telephone, Mobile calls, Private networks
Privacy	Low (signal available to everyone in range)	High (dedicated connection between endpoints)
Efficiency	High for mass communication	Better for personal/private communication

Mnemonic: "BDPEC" - Broadcasting Distributes to Public, Endpoints Connect in point-to-point

Question 1(b) [4 marks]

Define: Bit Rate, Baud Rate, Bandwidth and Repeater Distance.

Answer:

Term	Definition
Bit Rate	Number of binary bits transmitted per second (bps). Measures actual data transfer speed.
Baud Rate	Number of signal units or symbols transmitted per second. One symbol may contain multiple bits.
Bandwidth	Range of frequencies used by a signal, measured in Hertz (Hz). Determines maximum data capacity of a channel.
Repeater Distance	Maximum distance between repeaters in a communication system before signal degradation requires regeneration.

Diagram:

graph LR
    A[Signal] --> B[Bandwidth = Max Frequency - Min Frequency]
    C[Bits] --> D[Bit Rate = Bits/Second]
    E[Symbols] --> F[Baud Rate = Symbols/Second]
    G[Distance] --> H[Repeater Distance = Max Distance Before Signal Regeneration]

Mnemonic: "BBRR" - "Better Bandwidth Requires Repeaters"

Question 1(c) [7 marks]

Draw the block diagram of digital communication system. Explain the functions of each block in brief. State advantages and disadvantages of it.

Answer:

Block Diagram:

graph LR
    A[Input Source] --> B[Source Encoder]
    B --> C[Channel Encoder]
    C --> D[Digital Modulator]
    D --> E[Channel]
    E --> F[Digital Demodulator]
    F --> G[Channel Decoder]
    G --> H[Source Decoder]
    H --> I[Output]

Functions:

Block	Function
Source Encoder	Converts analog signal to digital, removes redundancy, compresses data
Channel Encoder	Adds redundancy for error detection and correction
Digital Modulator	Converts digital data to suitable form for transmission (ASK, FSK, PSK, etc.)
Channel	Medium through which signal travels (wired/wireless)
Digital Demodulator	Extracts original digital data from received modulated signal
Channel Decoder	Detects and corrects errors using added redundancy
Source Decoder	Decompresses data and converts to original form

Advantages and Disadvantages:

Advantages	Disadvantages
Better noise immunity	Requires more bandwidth
Easier signal regeneration	Complex implementation
Secure transmission possible	Synchronization required
Integration with computers	Quantization errors
Better quality for long distance	Higher cost for simple applications

Mnemonic: "SECDCSO" - "Secure Encoding Creates Digital Communication System Output"

Question 1(c) OR [7 marks]

Justify the needs of multiplexing techniques for digital communication. Draw and explain Time Division multiplexing technique in brief. Discuss its merits and demerits.

Answer:

Need for Multiplexing:

Need	Explanation
Channel Efficiency	Allows multiple signals on one channel, saving bandwidth
Cost Reduction	Reduces need for multiple transmission media
Infrastructure Utilization	Maximizes use of expensive infrastructure
Spectrum Conservation	Conserves limited frequency spectrum

Time Division Multiplexing (TDM):

graph LR
    A1[Input 1] --> M[Multiplexer]
    A2[Input 2] --> M
    A3[Input 3] --> M
    A4[Input 4] --> M
    M --> T[Transmission Channel]
    T --> D[Demultiplexer]
    D --> B1[Output 1]
    D --> B2[Output 2]
    D --> B3[Output 3]
    D --> B4[Output 4]

Working: In TDM, each input signal gets a specific time slot. The multiplexer samples each input sequentially, combining them into a single high-speed data stream. At the receiver, the demultiplexer separates the stream back into original signals based on timing.

Merits and Demerits:

Merits	Demerits
Efficient bandwidth usage	Requires synchronization
No guard bands needed	Complex buffering required
No cross-talk	Timing issues can cause errors
Flexible allocation	Unused slots waste capacity
Digital implementation	Higher data rate than individual channels

Mnemonic: "TIME" - "Transmission Interleaves Multiple Endpoints"

Question 2(a) [3 marks]

Differentiate: Coherent and Non-Coherent Detection Technique.

Answer:

Parameter	Coherent Detection	Non-Coherent Detection
Phase Information	Uses phase information	Ignores phase information
Local Oscillator	Required	Not required
Complexity	More complex	Simpler
Performance	Better noise immunity	Less efficient in noise
Implementation	Difficult	Easier
Applications	High-quality systems	Low-cost systems

Mnemonic: "PLCPIA" - "Phase Local Complex Performance Implementation Applications"

Question 2(b) [4 marks]

Sketch the ASK, FSK, PSK and QPSK waveform for the data sequence 101100110110.

Answer:

Input Data:  1  0  1  1  0  0  1  1  0  1  1  0
            ▄▄    ▄▄▄▄       ▄▄▄▄    ▄▄▄▄    
            │ │   │  │       │  │    │  │    
Data:       │ │   │  │       │  │    │  │    
            │ └───┘  └───────┘  └────┘  └────
            
            ▄▄    ▄▄▄▄       ▄▄▄▄    ▄▄▄▄    
            │ │   │  │       │  │    │  │    
ASK:        │ │   │  │       │  │    │  │    
            └─┴───┴──┴───────┴──┴────┴──┴────
            
            ▄▄▄▄  ████▄▄▄▄▄  ████▄▄  ████▄▄  
FSK High:   │  │  │  │    │  │  │ │  │  │ │  
FSK Low:   ─┘  └──┘  └────┘──┘  └─┘──┘  └─┘──
            
            ▄▄    ▄▄▄▄       ▄▄▄▄    ▄▄▄▄    
            │ │   │  │       │  │    │  │    
PSK 0°:     │ │   │  │       │  │    │  │    
            │ └───┘  └───────┘  └────┘  └────
PSK 180°:  ─┘     ▄▄     ▄▄▄▄▄▄     ▄▄     ▄▄
                  │ │    │    │     │ │    │ 
                  │ │    │    │     │ │    │ 
                  └─┘    └────┘     └─┘    └─

QPSK:     ┌─┐   ┌─┐ ┌─┐   ┌─┐ ┌─┐   ┌─┐ ┌─┐ 
90° 00:  _│ │___│ │_│ │___│ │_│ │___│ │_│ │__
180° 10: _┘ └───┘ └─┘ └───┘ └─┘ └───┘ └─┘ └__
270° 11: ───┐ ┌───┐   ┌───┐   ┌───┐   ┌──────
0° 01:   ───┘ └───┘   └───┘   └───┘   └──────

Mnemonic: "AFPQ" - "Amplitude Frequency Phase Quadrature"

Question 2(c) [7 marks]

Explain the principle of 16-QAM. Also explain constellation diagram and waveform for 16-QAM. Write its advantages and disadvantages.

Answer:

Principle of 16-QAM: 16-QAM (Quadrature Amplitude Modulation) combines amplitude and phase modulation to transmit 4 bits per symbol. It uses 16 different combinations of amplitude and phase, allowing higher data rates in the same bandwidth.

Constellation Diagram:

           Q
           ▲
           │
   ●   ●   │   ●   ●
           │
   ●   ●   │   ●   ●
-----------+-----------> I
   ●   ●   │   ●   ●
           │
   ●   ●   │   ●   ●
           │
           
Each point represents 4 bits (0000 to 1111)

Waveform: The 16-QAM waveform varies in both amplitude (4 levels) and phase (4 phases), creating 16 unique symbols.

Advantages and Disadvantages:

Advantages	Disadvantages
High spectral efficiency	Sensitive to noise and interference
Higher data rate	Requires higher SNR
Bandwidth efficient	Complex implementation
Better use of channel capacity	Susceptible to amplitude distortion

Mnemonic: "SCHAP" - "Sixteen Combinations Have Amplitude and Phase"

Question 2(a) OR [3 marks]

Compare: ASK and PSK

Answer:

Parameter	ASK (Amplitude Shift Keying)	PSK (Phase Shift Keying)
Modulation Parameter	Amplitude	Phase
Noise Immunity	Poor	Good
Power Efficiency	Less efficient	More efficient
Bandwidth Efficiency	Lower	Higher
Implementation	Simple	More complex
BER Performance	Higher error rate	Lower error rate

Mnemonic: "ANPBIP" - "Amplitude Noise Power Bandwidth Implementation Performance"

Question 2(b) OR [4 marks]

Draw the block diagram of BPSK modulator and demodulator.

Answer:

BPSK Modulator:

graph LR
    A[Binary Input] --> B[NRZ Encoder]
    B --> C[Multiplier]
    D[Carrier Generator] --> C
    C --> E[BPSK Output]

BPSK Demodulator:

graph LR
    A[BPSK Input] --> B[Multiplier]
    C[Local Oscillator] --> D[Phase Synchronizer]
    D --> B
    B --> E[Low Pass Filter]
    E --> F[Decision Device]
    F --> G[Binary Output]

Mnemonic: "MNECO" - "Modulation Needs Encoding, Carriers, Oscillators"

Question 2(c) OR [7 marks]

Explain QPSK generation and detection with the help of block diagram and waveform. Discuss its advantages and disadvantages.

Answer:

QPSK Generation Block Diagram:

graph LR
    A[Binary Input] --> B[Serial to Parallel]
    B -->|I-channel| C[Multiplier I]
    B -->|Q-channel| D[Multiplier Q]
    E[Carrier Generator] --> C
    E --> F[90° Phase Shifter]
    F --> D
    C --> G[Adder]
    D --> G
    G --> H[QPSK Output]

QPSK Detection Block Diagram:

graph LR
    A[QPSK Input] --> B[Multiplier I]
    A --> C[Multiplier Q]
    D[Local Oscillator] --> B
    D --> E[90° Phase Shifter]
    E --> C
    B --> F[LPF I]
    C --> G[LPF Q]
    F --> H[Decision Device I]
    G --> I[Decision Device Q]
    H --> J[Parallel to Serial]
    I --> J
    J --> K[Binary Output]

QPSK Waveform: Each symbol in QPSK represents 2 bits, with 4 possible phase states (0°, 90°, 180°, 270°).

Advantages and Disadvantages:

Advantages	Disadvantages
Twice the data rate of BPSK	More complex implementation
Same bandwidth as BPSK	Sensitive to phase errors
Good noise immunity	Requires carrier recovery
Spectral efficiency	More complex synchronization

Mnemonic: "PACE" - "Phase Alteration Carries Extra data"

Question 3(a) [3 marks]

State the features of RS-422.

Answer:

Features of RS-422
Differential signaling for noise immunity
Maximum data rate of 10 Mbps
Maximum cable length of 1200 meters
Multi-drop capability (1 driver, up to 10 receivers)
Balanced transmission line
Higher noise immunity than RS-232

Mnemonic: "DMMBHN" - "Differential Maximum Multi-drop Balanced Higher Noise-immunity"

Question 3(b) [4 marks]

Define: Entropy, Information, Mutual Information and Probability.

Answer:

Term	Definition
Entropy	Measure of uncertainty or randomness in a message source, calculated as H(X) = -∑p(x)log₂p(x)
Information	Reduction in uncertainty when a message is received, measured in bits
Mutual Information	Measure of dependency between two random variables, indicating how much information one variable contains about the other
Probability	Mathematical measure of likelihood that an event will occur, ranging from 0 (impossible) to 1 (certain)

Diagram:

graph LR
    A["Entropy of X: H(X)"] --- C["Mutual Information: I(X;Y)"]
    B["Entropy of Y: H(Y)"] --- C
    C --- D[Measures shared information between X and Y]

Mnemonic: "EIMP" - "Entropy Information Measures Probability"

Question 3(c) [7 marks]

Explain Huffman Code and Shannon-Fano code with suitable example.

Answer:

Huffman Code: Huffman coding assigns variable-length codes to symbols based on their frequencies, with shorter codes for more frequent symbols.

Example:

Symbol	Frequency	Huffman Code
A	45%	0
B	25%	10
C	15%	110
D	10%	1110
E	5%	1111

Huffman Tree:

graph LR
    A[100%] --> B[60%]
    A --> C[A: 40%/0]
    B --> D[30%]
    B --> E[B: 30%/10]
    D --> F[15%]
    D --> G[C: 15%/110]
    F --> H[D: 10%/1110]
    F --> I[E: 5%/1111]

Shannon-Fano Code: Shannon-Fano algorithm recursively divides symbols into two groups of similar frequency, then assigns 0 to one group and 1 to the other.

Example:

Symbol	Frequency	Shannon-Fano Code
A	45%	0
B	25%	10
C	15%	110
D	10%	1110
E	5%	1111

Shannon-Fano Tree:

graph LR
    A[A,B,C,D,E] --> B[A/0]
    A --> C[B,C,D,E]
    C --> D[B/10]
    C --> E[C,D,E]
    E --> F[C/110]
    E --> G[D,E]
    G --> H[D/1110]
    G --> I[E/1111]

Mnemonic: "FREDS" - "Frequency Reduces Encoding Digit Size"

Question 3(a) OR [3 marks]

State the features of RS-232.

Answer:

Features of RS-232
Single-ended signaling
Maximum data rate of 20 kbps
Maximum cable length of 15 meters
Point-to-point communication (1 driver, 1 receiver)
Voltage levels: -15V to +15V
25-pin or 9-pin DB connector standard

Mnemonic: "SMPVD" - "Single Maximum Point-to-point Voltage DB-connector"

Question 3(b) OR [4 marks]

What is channel capacity in terms of SNR? Explain its importance.

Answer:

Channel Capacity: The maximum rate at which information can be transmitted over a communication channel with an arbitrarily small probability of error.

Formula: C = B × log₂(1 + SNR)

Where:

C = Channel capacity in bits per second
B = Bandwidth in Hertz
SNR = Signal-to-Noise Ratio

Importance:

Importance of Channel Capacity
Sets theoretical limits for data transmission
Guides system design and optimization
Helps evaluate performance of communication systems
Determines required bandwidth for a given data rate
Informs coding techniques to approach capacity

Diagram:

graph LR
    A[Bandwidth] --> C[Channel Capacity]
    B[SNR] --> C
    C --> D[Maximum Achievable Data Rate]

Mnemonic: "BSNR" - "Bandwidth and SNR Need Relationship"

Question 3(c) OR [7 marks]

Explain in detail any one error detection and error correction technique in digital communication.

Answer:

Hamming Code Error Detection and Correction

Hamming code is a linear error-correcting code that can detect and correct single-bit errors in data transmission.

Working Principle:

Data bits are positioned at locations that are powers of 2 (1, 2, 4, 8, etc.)
Parity bits are added at positions 1, 2, 4, 8, etc.
Each parity bit checks specific data bits according to its position
On receiving, parity checks identify error position

Example: 7-bit Hamming code (4 data bits, 3 parity bits)

Position	1	2	3	4	5	6	7
Bit type	P₁	P₂	D₁	P₄	D₂	D₃	D₄

Parity Bit Calculation:

P₁ checks bits 1, 3, 5, 7 (positions 1, 3, 5, 7)
P₂ checks bits 2, 3, 6, 7 (positions 2, 3, 6, 7)
P₄ checks bits 4, 5, 6, 7 (positions 4, 5, 6, 7)

Error Correction: If an error occurs, the parity checks will indicate the error position, which can then be flipped to correct the error.

Table: Error Position from Parity Check Results

P₄	P₂	P₁	Error Position
0	0	0	No error
0	0	1	Position 1
0	1	0	Position 2
0	1	1	Position 3
1	0	0	Position 4
1	0	1	Position 5
1	1	0	Position 6
1	1	1	Position 7

Mnemonic: "PECD" - "Parity Enables Correction of Data"

Question 4(a) [3 marks]

Draw the block diagram of satellite communication and explain in brief.

Answer:

Satellite Communication Block Diagram:

graph LR
    A[Ground Station 1] -->|Uplink| B[Satellite]
    B -->|Downlink| C[Ground Station 2]
    D[Transmitter] --> A
    C --> E[Receiver]

Brief Explanation: Satellite communication involves transmitting signals from an Earth station to a satellite (uplink), which then amplifies and retransmits the signals back to Earth (downlink). The satellite acts as a repeater in space, enabling long-distance communication.

Key Components:

Earth Stations: Transmit and receive signals
Transponders: Receive, amplify, and retransmit signals
Antennas: Transmit and receive electromagnetic waves
Modems: Convert digital data to analog signals and vice versa

Mnemonic: "STAR" - "Satellite Transmits And Receives"

Question 4(b) [4 marks]

Sketch the Unipolar NRZ, Polar RZ, Polar NRZ and AMI waveform for 10101101 data sequence.

Answer:

Input Data:  1  0  1  0  1  1  0  1
            ▄▄    ▄▄    ▄▄▄▄    ▄▄  
            │ │   │ │   │  │    │ │ 
Data:       │ │   │ │   │  │    │ │ 
            │ └───┘ └───┘  └────┘ └─
            
            ▄▄    ▄▄    ▄▄▄▄    ▄▄  
            │ │   │ │   │  │    │ │ 
Unipolar    │ │   │ │   │  │    │ │ 
NRZ:        │ └───┘ └───┘  └────┘ └─
            
            ┌┐    ┌┐    ┌┐┌┐    ┌┐
Polar       ││    ││    │││││   ││
RZ:         ││    ││    │││││   ││
           ─┘└────┘└────┘┘┘┘└───┘└─
            ▄▄    ▄▄    ▄▄▄▄    ▄▄
            │ │   │ │   │  │    │ │
Polar       │ │   │ │   │  │    │ │
NRZ:       ─┘ └───┐ └───┘  └────┘ └
                 │                  
                 └──────────────────
                 
            ▄▄         ▄▄         ▄▄
            │ │        │ │        │ │
AMI:        │ │        │ │        │ │
           ─┘ └────────┘ └────────┘ └
                ▄▄         ▄▄        
                │ │        │ │       
                │ │        │ │       
           ─────┘ └────────┘ └───────

Mnemonic: "UPPA" - "Unipolar Polar Polar AMI"

Question 4(c) [7 marks]

Explain data transmission techniques in details with suitable example for digital communication.

Answer:

Data Transmission Techniques:

Technique	Description	Example
Serial Transmission	Data bits sent one after another over a single channel	USB, UART communication
Parallel Transmission	Multiple bits sent simultaneously over multiple channels	Printer ports, SCSI
Synchronous Transmission	Data sent in continuous stream with timing signals	Ethernet, HDLC
Asynchronous Transmission	Data sent with start/stop bits as timing references	RS-232, UART
Simplex	One-way communication	TV broadcasting
Half-Duplex	Two-way communication, one direction at a time	Walkie-talkie
Full-Duplex	Two-way simultaneous communication	Telephone calls

Serial Transmission Example:

            Start   1  0  1  0  1  1  0  1  Stop
             bit                          bit
            ┌───┐  ┌┐   ┌┐   ┌┐┌┐   ┌┐  ┌───┐
            │   │  ││   ││   │││││  ││  │   │
UART:       │   │  ││   ││   │││││  ││  │   │
          ──┘   └──┘└───┘└───┘┘┘┘└──┘└──┘   └──

Parallel Transmission Example:

Data: 10101101

      Bit 7: ──────┐    ┌────────
                   │    │          
      Bit 6: ──────┘    └────────
                   
      Bit 5: ───────────────────
                   
      Bit 4: ──────┐    ┌────────
                   │    │          
      Bit 3: ──────┘    └────────
                   
      Bit 2: ──────┐          ┌───
                   │          │   
      Bit 1: ──────┘          └───
                   
      Bit 0: ──────┐    ┌────┐    ┌
                   │    │    │    │
           ────────┘    └────┘    └
                   
Clock:      ┌─┐  ┌─┐  ┌─┐  ┌─┐  ┌─┐
            │ │  │ │  │ │  │ │  │ │
            │ │  │ │  │ │  │ │  │ │
          ──┘ └──┘ └──┘ └──┘ └──┘ └─

Mnemonic: "SPASH" - "Serial Parallel Asynchronous Synchronous Half-duplex"

Question 4(a) OR [3 marks]

Interpret the aspects of spread spectrum techniques.

Answer:

Spread Spectrum Techniques:

Aspect	Interpretation
Bandwidth Spreading	Signal spread over a wider bandwidth than required
Security	Difficult to intercept or jam due to spreading
Noise Immunity	Resistant to narrowband interference
Multiple Access	Allows multiple users to share same frequency band
Low Power Density	Signal power spread across wide band, appearing as noise

Diagram:

graph LR
    A[Narrow Band Signal] --> B[Spreading]
    B --> C[Wideband Spread Signal]
    D[Spreading Code] --> B

Mnemonic: "BSNML" - "Bandwidth Security Noise Multiple Low-power"

Question 4(b) OR [4 marks]

Write a short note on probability and discuss its properties for digital communication.

Answer:

Probability in Digital Communication: Probability theory provides the mathematical foundation for analyzing performance, error rates, and reliability of digital communication systems.

Properties of Probability:

Property	Description	Relevance in Digital Communication
Range	0 ≤ P(E) ≤ 1	Sets bounds for error probability
Certainty	P(S) = 1 for sample space S	Total probability of all possible outcomes
Additivity	P(A∪B) = P(A) + P(B) for disjoint events	Calculating overall system error rates
Conditional Probability	P(A\|B) = P(A∩B)/P(B)	Useful for channel modeling
Independence	P(A∩B) = P(A)×P(B)	Analyzing uncorrelated noise sources

Applications in Digital Communication:

Bit Error Rate calculation
Signal detection theory
Channel capacity estimation
Coding efficiency analysis

Mnemonic: "RACIC" - "Range Additivity Certainty Independence Conditional"

Question 4(c) OR [7 marks]

Explain Data transmission mode in details with example.

Answer:

Data Transmission Modes:

Mode	Description	Diagram	Example
Simplex	One-way communication only. Transmitter can only send, receiver can only receive.	```mermaid graph LR; A[Transmitter] -->	One-way
Half-Duplex	Two-way communication, but only one direction at a time.	```mermaid graph LR; A[Device A] -->	Time 1
Full-Duplex	Two-way simultaneous communication.	```mermaid graph LR; A[Device A] -->	Channel 1

Example of Half-Duplex Communication:

    Device A                     Device B
       |                            |
       |        REQUEST DATA        |
       |--------------------------->|
       |                            |
       |                            |
       |        SENDING DATA        |
       |<---------------------------|
       |                            |
       |    ACKNOWLEDGMENT (ACK)    |
       |--------------------------->|
       |                            |

Example of Full-Duplex Communication:

    Device A                     Device B
       |                            |
       |        SENDING DATA        |
       |--------------------------->|
       |                            |
       |        SENDING DATA        |
       |<---------------------------|
       |                            |
       |      CONTINUOUS DATA       |
       |<-------------------------->|
       |                            |

Mnemonic: "SHF" - "Simplex Half Full" or "Stop, Halt, Flow"

Question 5(a) [3 marks]

Explain Edge Computing in detail.

Answer:

Edge Computing: Edge computing is a distributed computing paradigm that brings computation and data storage closer to the location where it is needed to improve response times and save bandwidth.

Key Aspects:

Aspect	Description
Decentralization	Processing at network edge instead of central cloud
Reduced Latency	Faster response due to proximity to data source
Bandwidth Efficiency	Less data sent to cloud, reducing network congestion
Local Data Processing	Data processed near collection point
Improved Security	Sensitive data remains local, reducing exposure
Reliability	Continues to function during cloud connectivity issues

Diagram:

graph LR
    A[IoT Devices] --> B[Edge Computing]
    B --> C[Local Processing]
    B --> D[Local Storage]
    B --> E[Cloud]
    E --> F[Central Storage & Processing]

Mnemonic: "DRBLES" - "Decentralized Reduces Bandwidth, Latency, Exposure, Strengthens reliability"

Question 5(b) [4 marks]

Enlist the features of 5G Technology in data communication.

Answer:

Features of 5G Technology
High Data Rates (up to 20 Gbps peak)
Ultra-Low Latency (1 ms or less)
Massive Device Connectivity (1 million devices per km²)
Network Slicing (customized virtual networks)
Beamforming (directed signal transmission)
Millimeter Wave Spectrum (24-100 GHz)
Enhanced Mobile Broadband (eMBB)
Ultra-Reliable Low-Latency Communication (URLLC)

Diagram:

graph TD
    A[5G Technology] --> B[High Data Rates]
    A --> C[Ultra-Low Latency]
    A --> D[Massive Connectivity]
    A --> E[Network Slicing]
    A --> F[Three Main Use Cases]
    F --> G[eMBB]
    F --> H[URLLC]
    F --> I[mMTC]

Mnemonic: "HUMBLE-MN" - "High-speed Ultra-low-latency Massive Beamforming Low-latency Enhanced Millimeter Network"

Question 5(c) [7 marks]

Write a details note on Data communication including its characteristics and components.

Answer:

Data Communication: Data communication is the process of transferring digital information between two or more points.

Characteristics of Data Communication:

Characteristic	Description
Delivery	System must deliver data to correct destination
Accuracy	System must deliver data accurately, without errors
Timeliness	System must deliver data in a timely manner
Jitter	System must maintain consistent timing between data arrivals
Security	System must protect data from unauthorized access

Components of Data Communication:

Component	Description
Message	The information (data) to be communicated
Sender	Device that sends the data message
Receiver	Device that receives the message
Transmission Medium	Physical path by which message travels
Protocol	Set of rules governing data communication

Data Communication Model:

graph LR
    A[Sender] --> B[Encoder]
    B --> C[Transmission Medium]
    C --> D[Decoder]
    D --> E[Receiver]
    F[Protocol] --> A
    F --> B
    F --> C
    F --> D
    F --> E

Data Communication Types:

Type	Description
Analog	Continuous signal that varies in amplitude or frequency
Digital	Discrete signal represented by binary digits (0s and 1s)
Parallel	Multiple bits transmitted simultaneously on separate channels
Serial	Bits transmitted sequentially on a single channel

Mnemonic: "DATJS-MSRTP" - "Delivery Accuracy Timeliness Jitter Security - Message Sender Receiver Transmission Protocol"

Question 5(a) OR [3 marks]

Identify and write privacy consideration in Data communication.

Answer:

Privacy Considerations in Data Communication:

Privacy Consideration	Description
Data Encryption	Protecting data during transmission using encryption algorithms
Access Control	Ensuring only authorized users can access communication systems
Authentication	Verifying the identity of users and devices
Data Minimization	Collecting only necessary data to minimize privacy risks
Secure Protocols	Using communication protocols with built-in security features
End-to-End Security	Ensuring data is protected throughout the entire communication path

Diagram:

graph TD
    A[Privacy in Data Communication] --> B[Data Encryption]
    A --> C[Access Control]
    A --> D[Authentication]
    A --> E[Data Minimization]
    A --> F[Secure Protocols]
    A --> G[End-to-End Security]

Mnemonic: "DAAESE" - "Data is Authenticated, Accessed, Encrypted Securely End-to-end"

Question 5(b) OR [4 marks]

What is block chain in communication security? Enlist its features.

Answer:

Blockchain in Communication Security: Blockchain is a distributed ledger technology that provides secure, tamper-proof record-keeping for data communication through cryptographic linking of data blocks.

Features of Blockchain:

Feature	Description
Decentralization	No central authority; distributed across network nodes
Immutability	Once recorded, data cannot be altered without consensus
Transparency	All transactions visible to authorized participants
Cryptographic Security	Data secured using advanced cryptographic techniques
Consensus Mechanism	Network agrees on validity of transactions
Smart Contracts	Self-executing contracts with terms directly written in code
Distributed Storage	Data stored across multiple nodes, preventing single point of failure

Diagram:

graph LR
    A[Block 1] -->|Hash Link| B[Block 2]
    B -->|Hash Link| C[Block 3]
    C -->|Hash Link| D[Block 4]

    A --> A1[Transactions]
    A --> A2[Hash]
    A --> A3[Previous Hash]
    
    B --> B1[Transactions]
    B --> B2[Hash]
    B --> B3[Previous Hash]

Mnemonic: "DITCSD" - "Decentralized Immutable Transparent Cryptographic Secure Distributed"

Question 5(c) OR [7 marks]

Write and illustrate different communication ports: USB, HDMI, RCA and Ethernet.

Answer:

Communication Ports:

USB (Universal Serial Bus):

    ┌───────────┐
    │           │
    │   USB-A   │
    │   ┌───┐   │
    │   │   │   │
    │   └───┘   │
    └───────────┘

    ┌───────────┐
    │           │
    │   USB-C   │
    │ ┌───────┐ │
    │ │       │ │
    │ └───────┘ │
    └───────────┘

Features:

Data transfer, power delivery, and device connection
Versions: USB 1.0 to USB 4.0
Speed: Up to 40 Gbps (USB4)
Hot-swappable
Supports up to 127 devices in cascade

HDMI (High-Definition Multimedia Interface):

    ┌─────────────────┐
    │                 │
    │      HDMI       │
    │  ┌───────────┐  │
    │  │           │  │
    │  └───────────┘  │
    └─────────────────┘

Features:

Digital audio/video transmission
Versions: HDMI 1.0 to HDMI 2.1
Resolution support: Up to 10K
Bandwidth: Up to 48 Gbps (HDMI 2.1)
HDCP (High-bandwidth Digital Content Protection)
CEC (Consumer Electronics Control) for device control

RCA (Radio Corporation of America):

    ┌───┐  ┌───┐  ┌───┐
    │   │  │   │  │   │
    │ R │  │ G │  │ B │
    │   │  │   │  │   │
    └───┘  └───┘  └───┘
    Red    Green  Blue
    
    ┌───┐  ┌───┐
    │   │  │   │
    │ W │  │ R │
    │   │  │   │
    └───┘  └───┘
    White  Red
    Video  Audio

Features:

Analog audio/video transmission
Color-coded connectors (Red, White, Yellow)
Used for composite video and stereo audio
Simple connection but limited quality
No digital content protection
Being phased out by digital standards

Ethernet (RJ-45):

    ┌───────────────┐
    │               │
    │    RJ-45      │
    │ ┌───────────┐ │
    │ │|||||||||  │ │
    │ └───────────┘ │
    └───────────────┘

Features:

Network connectivity
Standards: 10BASE-T to 10GBASE-T
Speed: 10 Mbps to 10 Gbps
Uses twisted-pair cabling (Cat5e, Cat6, Cat6a)
Supports Power over Ethernet (PoE)
Base communication for TCP/IP networks
Maximum cable length: 100 meters

Comparison Table:

Port	Type	Data Type	Max Speed	Power Delivery	Max Length
USB	Digital	Data/Power	40 Gbps	Yes (100W)	5m
HDMI	Digital	Audio/Video	48 Gbps	Limited	15m
RCA	Analog	Audio/Video	Low	No	10m
Ethernet	Digital	Network Data	10 Gbps	Yes (PoE)	100m

Mnemonic: "UHRE" - "USB Handles Rapid Ethernet, HDMI Delivers Rich Entertainment"