5G — Fifth Generation Mobile Network

Overview

5G is the fifth generation of cellular network technology, designed for enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC).

5G vs 4G LTE

5G Use Cases

graph TD
    A[5G Use Cases] --> B[eMBB<br>Enhanced Mobile Broadband]
    A --> C[URLLC<br>Ultra-Reliable Low Latency]
    A --> D[mMTC<br>Massive Machine Type Comms]
    B --> E[4K/8K video streaming]
    B --> F[AR/VR]
    B --> G[Fixed wireless access]
    C --> H[Autonomous vehicles]
    C --> I[Remote surgery]
    C --> J[Industrial automation]
    D --> K[Smart cities]
    D --> L[IoT sensors]
    D --> M[Smart agriculture]

5G Frequency Bands

mmWave Challenges

• Range: ~500m (needs many small cells)
• Blockage: Walls, trees, even rain attenuate signal
• Line-of-sight: Requires direct or reflected paths
• Cost: Many cells needed for coverage

5G Architecture

graph TD
    subgraph "Radio Access Network (RAN)"
        UE[User Equipment]
        gNB[gNodeB]
        UE --> gNB
    end
    subgraph "5G Core (5GC) - Service Based Architecture"
        AMF[AMF<br>Access & Mobility]
        SMF[SMF<br>Session Management]
        UPF[UPF<br>User Plane Function]
        AUSF[AUSF<br>Authentication]
        UDM[UDM<br>Unified Data Mgmt]
        PCF[PCF<br>Policy Control]
        NRF[NRF<br>Network Repository]
    end
    gNB --> AMF
    AMF --> SMF
    SMF --> UPF
    UPF --> DN[Data Network / Internet]
    AMF --> AUSF
    AUSF --> UDM
    PCF --> SMF

5G Core Components

Network Slicing

5G introduces network slicing — creating multiple virtual networks on the same physical infrastructure:

graph TD
    subgraph "Physical 5G Network"
        RAN[Shared RAN]
        CORE[Shared Core]
    end
    subgraph "Slice 1: eMBB"
        S1[High bandwidth<br>Video streaming]
    end
    subgraph "Slice 2: URLLC"
        S2[Low latency<br>Autonomous vehicles]
    end
    subgraph "Slice 3: mMTC"
        S3[Massive connections<br>IoT sensors]
    end
    RAN --> S1
    RAN --> S2
    RAN --> S3
    CORE --> S1
    CORE --> S2
    CORE --> S3

Each slice has independent: QoS, security policies, resource allocation, and management.

5G vs WiFi 6

Interview Questions

1. Q: What are the three main use cases of 5G? A: 1) eMBB (Enhanced Mobile Broadband) — high-speed data (4K video, AR/VR). 2) URLLC (Ultra-Reliable Low Latency) — mission-critical (autonomous vehicles, remote surgery). 3) mMTC (Massive Machine Type Communications) — IoT (smart cities, sensors).

2. Q: What is network slicing in 5G? A: Creating multiple virtual networks on the same physical infrastructure. Each slice has independent QoS, security, and resources. Example: one slice for high-bandwidth video, another for low-latency autonomous driving, another for IoT sensors.

3. Q: What is mmWave and what are its challenges? A: mmWave (24-100 GHz) provides extreme bandwidth (multiple Gbps) but: short range (~500m), blocked by walls/trees/rain, requires line-of-sight, and needs many small cells. Used for dense urban areas and stadiums.

4. Q: How does 5G achieve lower latency than 4G? A: 1) Edge computing (MEC — Multi-access Edge Computing) processes data closer to users. 2) Shorter TTI (Transmission Time Interval). 3) Grant-free uplink (no scheduling request needed). 4) Network function placement closer to the edge.

5. Q: What is the 5G Service-Based Architecture (SBA)? A: 5G core uses SBA where network functions communicate via APIs (HTTP/2). Each function (AMF, SMF, UPF) is a microservice that registers with NRF for discovery. This enables cloud-native deployment and scalability.

Common Mistakes

• Confusing 5G frequency bands (low/mid/high have very different characteristics)
• Assuming 5G replaces WiFi (they’re complementary)
• Not understanding network slicing (it’s not just VPNs)
• Forgetting that 5G standalone (SA) vs non-standalone (NSA) are different architectures
• Assuming 5G latency is always 1ms (depends on deployment and edge computing)

Summary

5G brings extreme speed (20 Gbps), low latency (1-10ms), and massive connectivity (1M devices/km²). Network slicing enables virtual networks for different use cases. The service-based architecture (SBA) makes 5G core cloud-native. mmWave provides extreme bandwidth but limited range.

Cross-References

• Wireless Overview
• WiFi — Complementary technology
• SDN — Software-defined networking enables slicing
• NFV — Virtualized network functions
• Edge Computing — MEC in 5G

Cross References

• WiFi
• NFV
• SDN