Evolution 1G to 5G

Tip

Exam Focus

Reproduce the 1G $\to$ 5G table (era, radio/access method, service, key feature) and the 5G service classes (eMBB, URLLC, mMTC); explain the cellular concept and why hexagons; and label the GSM/LTE architecture (BTS/BSC/MSC/HLR/VLR; eNodeB/gNodeB, EPC/5GC). A generations description ([5–10]) is near-certain.

Wireless Communication

Wireless communication transfers information between points without physical conductors, using electromagnetic waves (radio, microwave, infrared, satellite).

Basic wireless link: source $\to$ modulator/transmitter $\to$ antenna $\to$ radio channel $\to$ antenna $\to$ receiver/demodulator $\to$ destination.

Note

Key Point — Advantages and limitations

• Advantages: mobility; fast deployment (no cabling to each user); wide/rural coverage; scalability; flexible voice/data/IoT/multimedia.

• Limitations: scarce, regulated spectrum; interference; multipath fading and shadowing; interception/security risk; battery-power constraints.

Evolution from 1G to 5G

Gen	Era	Technology / access	Key service
1G	1980s	Analog FM, FDMA	Analog voice
2G	1990s	GSM (TDMA), IS-95 (CDMA)	Digital voice, SMS
2.5/2.75G	late 1990s	GPRS, EDGE	Packet data
3G	2000s	WCDMA/UMTS, CDMA2000	Mobile broadband, video call
4G	2010s	LTE: OFDMA, MIMO	All-IP broadband, VoLTE
5G	2020s	NR: massive MIMO, mmWave, slicing	eMBB, URLLC, mMTC

Mobile-generation summary.

• 1G: analog, voice-only, FDMA, low capacity/weak security (AMPS, NMT, TACS).

• 2G: digital voice + SMS, encryption, better efficiency; GPRS/EDGE add packet data.

• 3G: multimedia and mobile internet (WCDMA/CDMA2000).

• 4G: all-IP, OFDMA + MIMO, high data rate (LTE/LTE-A, VoLTE).

• 5G: NR air interface, sub-6 GHz + mmWave, massive MIMO, beamforming, small cells, network slicing, edge computing.

5G class	Meaning	Examples
eMBB	Enhanced Mobile Broadband	4K/8K video, fast internet
URLLC	Ultra-Reliable Low-Latency	Remote control, automation
mMTC	Massive Machine-Type Comm.	IoT sensors, smart meters

5G service categories.

Caution

Key Formula — AWGN capacity limit

$$C=B\log_2\!\Big(1+\frac{S}{N}\Big)\ bit/s.$$

Each generation approaches a larger useful fraction of this Shannon limit through higher-order modulation, stronger coding, wider aggregated bandwidth and spatial multiplexing (MIMO).

The Cellular Concept

The cellular concept divides a service area into many small cells, each served by a low-power base station; the same channels are reused in cells separated by enough distance.

Benefits: higher capacity through frequency reuse, lower transmit power, planned coverage, mobility and handover support. Real coverage is irregular, but hexagons are used as a planning model because they tessellate without gaps/overlaps, approximate a circle better than a square, give six equidistant neighbours and simple reuse geometry.

Caution

Key Formula — Hexagonal cell area

$$A_c=\frac{3\sqrt3}{2}R^2,$$

$R=$ cell radius (hexagon side).

Cell	Coverage	Use
Macrocell	Several km	Rural / wide area
Microcell	m–few km	Urban
Picocell	Tens of metres	Offices, malls
Femtocell	Home/small office	Indoor (broadband backhaul)
Small cell	Umbrella term	Low-power cells for dense-area capacity

Cell types by coverage.

Cellular Network Architecture

GSM element	Function
MS	Mobile station (handset + SIM)
BTS	Base transceiver station (radio for a cell)
BSC	Base station controller (controls BTSs, handovers)
MSC	Mobile switching centre (switching, mobility)
HLR / VLR	Home / visitor location register (subscriber databases)
AuC / EIR	Authentication centre / equipment identity register

GSM core elements.

LTE/5G element	Function
eNodeB / gNodeB	LTE / 5G NR base station
EPC / 5GC	LTE / 5G core network
AMF	Access and mobility management (5G)
UPF	User-plane data forwarding (5G)

LTE/5G architecture terms.

Note

Key Point — Exam-ready model answer — 1G to 5G in one line

Analog voice (1G, FDMA) $\to$ secure digital voice/SMS (2G, TDMA/CDMA) $\to$ packet multimedia (3G, WCDMA) $\to$ all-IP broadband (4G, OFDMA+MIMO) $\to$ software-defined, beamformed, service-sliced connectivity (5G NR) with eMBB, URLLC and mMTC.