Network & Communication aspects in IoT
IoT means Internet of Things.
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IoT connects small devices (like sensors, smart watches, smart bulbs) to the internet.
These devices talk to each other and send data.
Example
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A smart temperature sensor in your classroom sends room temperature to your mobile app.
Wireless Medium Access Issues
What is Wireless Medium?
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Wireless means without wires.
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Medium means the path through which data travels (like air).
So, Wireless Medium = Data travels through air using signals.
Example
WiFi in your college works through air.
Bluetooth earphones connect without wires.
What is Medium Access?
Many devices want to send data.
They share the same air.
If all send at the same time → signals crash.
This problem is called Collision (when two signals mix and get damaged).
Example
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In class, if 5 students speak at the same time, teacher understands nothing.
Same happens in wireless network.
Main Wireless Medium Access Issues
1️⃣ Collision
Two devices send data at same time.
Data gets lost.
Example
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Two friends send voice notes at same time in group call → confusion.
2️⃣ Hidden Node Problem
Two devices cannot see each other.
Both send data to same receiver.
Receiver gets mixed signal.
Example
Two students sit far apart.
Both shout answer to teacher.
They don’t know about each other.
3️⃣ Exposed Node Problem
One device waits even when it could send data safely.
Example
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You stop speaking just because someone in another group talks, even if teacher can hear both clearly.
Exam Tip
👉 Draw small diagram of 3 nodes to explain hidden and exposed problem.
MAC Protocol Survey
What is MAC?
MAC means Medium Access Control.
It is a rule system.
It decides who will send data and when.
Think of it like traffic rules for data.
Example
Traffic signal controls cars.
MAC controls devices.
Types of MAC Protocols
| Type | Meaning | Simple Idea | Example |
|---|---|---|---|
| Contention Based | Devices compete | First come first send | Students raising hands |
| Controlled Access | Fixed order | Turn by turn | Roll number wise speaking |
| Scheduled | Time fixed | Time slot given | Class presentation schedule |
1️⃣ Contention Based Protocol
Devices compete.
If collision happens → try again.
Example: CSMA (Carrier Sense Multiple Access)
Means:
Device checks if channel is free.
Daily Life Example
Before speaking, you check if someone else talks.
2️⃣ TDMA (Time Division Multiple Access)
Each device gets fixed time.
No collision.
College Example
Each student gets 2 minutes for viva.
3️⃣ FDMA (Frequency Division Multiple Access)
Each device uses different frequency (different signal path).
Example
Different radio stations use different frequencies.
Remember This
✔ Contention → Simple but collision possible
✔ TDMA → No collision but
needs schedule
✔ FDMA → Uses separate frequency
Survey of Routing Protocols
What is Routing?
Routing means finding path to send data.
Data travels from sensor → gateway → internet.
Example
Swiggy delivery boy finds shortest path to your home.
Types of Routing in IoT
1️⃣ Flat Routing
All nodes are equal.
No boss node.
Example
Group study without leader.
2️⃣ Hierarchical Routing
One leader collects data.
Leader sends data to base station.
Example
Class representative collects assignments.
3️⃣ Location Based Routing
Uses location to send data.
Chooses nearest path.
Example
Google Maps shows nearest route.
Exam Tip
👉 Draw small tree diagram for hierarchical routing.
Sensor Deployment & Node Discovery
Sensor Deployment
Deployment means placing sensors in an area.
Types
1️⃣ Random Deployment
Drop sensors randomly.
Example: Forest fire detection.
2️⃣ Planned Deployment
Place sensors carefully.
Example: CCTV in college campus.
Node Discovery
Node means device.
Node discovery means:
Devices find each other.
Devices say “Hello, I am here.”
Example
Bluetooth shows nearby devices.
Why Important?
Devices must know neighbors.
Helps in routing.
Data Aggregation & Dissemination
Data Aggregation
Aggregation means combining data.
Many sensors send data.
Leader node combines it.
Sends one summary.
Example
50 students give attendance.
CR tells teacher “45 present”.
Benefits
Saves energy
Reduces traffic
Saves battery
Data Dissemination
Dissemination means spreading data.
Base station sends update to all nodes.
Example
Teacher sends notice in class group.
Everyone receives same message.
Types of Dissemination
One to many (Teacher to class)
Many to one (Students to teacher)
Many to many (Group discussion)
Important Exam Questions
Short Questions (2–5 Marks)
Define MAC protocol.
What is hidden node problem?
Define data aggregation.
What is node discovery?
List types of routing protocols.
Long Questions (10–15 Marks)
Explain wireless medium access issues with diagram.
Compare TDMA and CSMA.
Explain routing protocols in IoT.
Discuss data aggregation and dissemination.
Quick Revision Table
| Topic | Key Idea |
|---|---|
| Wireless Issues | Collision, Hidden, Exposed |
| MAC | Rules to control sending |
| Routing | Path finding |
| Deployment | Placing sensors |
| Node Discovery | Finding neighbors |
| Aggregation | Combine data |
| Dissemination | Spread data |
Key Points to Remember
IoT devices share wireless medium.
MAC prevents data collision.
Routing finds best path.
Deployment affects network performance.
Aggregation saves energy.
Dissemination spreads updates.
Final Summary (Quick Revision)
IoT devices communicate wirelessly.
Many devices share same channel.
MAC controls who sends data.
Routing selects best path.
Sensors must discover neighbors.
Aggregation reduces traffic.
Dissemination spreads information.
👉 If you remember Collision + MAC + Routing + Aggregation, you can answer most exam questions easily.