| Generation | Frequency band | PHY features | Data rate | Spectral Eff. (bps/Hz) |
|---|---|---|---|---|
| 1G | 850 MHz | FDMA, FM | N/A | N/A |
| 2G | 900 MHz, 1.8 GHz | TDMA/CDMA, GMSK/QPSK, FEC, PC | 10 Kbps | < 1 |
| 3G | 1.8–2.5 GHz | CDMA, QAM | 1–40 Mbps | 1–8 |
| 4G | 2–8 GHz | OFDMA, SC-FDMA, QAM, MIMO-OFDM | 100–600 Mbps | 15 |
| 5G |
1–6 GHz mm wave (26–28 GHz) < 1 GHz (massive IoT) visible light? |
massive MIMO, beamforming D2D, Full duplex, NOMA LDPC and Polar codes OFDM & variants (adapted to extremes?) |
multi-Gbps | several tens |
Waveform design is the major change between the generations
| Mobile Wireless Generations | Specifications |
|---|---|
| 1G | Voice, Analog traffic, FDMA |
| 2G | Voice, SMS, CS data transfer, TDMA |
| 3G | Voice, SMS, PS data transfer, CDMA |
| 4G | PS data, VOIP, OFDMA |
| 5G | OFDMA, NOMA, Beamforming |
1G
We've all heard about the evolution of G's, or, to put it another way, the evolution of wireless cellular networks from 1G to 5G. 1G (the first generation of wireless networks) was introduced in 1981. Only voice communication (by analog signals) was supported in 1G. It was able to handle a data rate of 2.4 kbps). There was no data communication. AMPS (Advanced mobile phone system), NMTS (nordic mobile phone system), TACS (total access communication system), etc. were the most popular 1G-access technologies at that time.
📖 Related Topic: FDMA (Frequency Division Multiple Access) was the primary multiple-access technique used in most 1G analog cellular systems.
2G
2G was launched in the mid-1990s, providing PSDN or data communication as well as voice communication. The predecessor technology, 1G, is also referred to as analog. However, on 2G, we were able to communicate via voice and data at 64 kbps. 2G was the first generation of telecommunications that provide internet browsing capabilities. However, the data rate was merely adequate for browsing. New variants of 2G were introduced, such as 2.5G, 2.75G, and so on. The issue with 2G was that it did not meet international standards. In the context of low data rate, higher handover latency, limited capacity of cells, data roaming, etc. - we see several issues in 2G. GSM (global system for mobile communication), CDMA (code division multiple access), IS-95, etc. were the popular 2G access technologies at that time.
2G Modulation Techniques:
Frequency division multiplexing (FDM) and time division multiplexing (FDM) modulation techniques were primarily used in 2G. 2G distributes the entire available frequency spectrum into multiple subbands using FDM. Then, to link many devices, TDM is used for each subband. read more ...
Frequency bands for 2G:
GSM stands for Global System for Mobile Communications. The operating frequency ranged from 900 to 1800 MHz. We've probably all heard about uplink and downlink in 2G or other networks. The frequency band utilized to transfer signals from a mobile station (MS) to a base station is referred to as the uplink frequency (BS). Downlink frequency refers to the frequency utilized to convey data or signals from the BS to the MS.
Bandwidth:
Each channel in 2G has a bandwidth of 200 kHz and is modulated using TDM. We know that we can connect multiple MSs to a single channel using this technique. Using TDM, 2G GSM can connect 8 users simultaneously over a single channel.
The cell coverage of 2G GSM:
Previously, there was the idea of a big cell tower that could transmit its signal over a large area. You can assume that a tall transmitter is located in the center of a city and that it covers the entire area. For example, in 1946, the wireless mobile signal was sent in this manner in New York City. Only 543 users could be added to the network. We couldn't reuse the frequency with that technology. However, as time went on, the number of users grew rapidly. Then there was the cellular (cellular network) concept. In a cellular 2G GSM network, we can reuse frequencies in cell towers when they are not too close or when interference is minimal. This allowed us a lot of flexibility in terms of connecting multiple devices at once.
Doppler Shift:
In a 2G network, Doppler shift is an inevitable parameter. When MSs travel closer to the BS or cell tower, the received frequency increases. When MSs move away from cell towers, on the other hand, the frequency of received signals decreases. It can be stated mathematically as a Doppler shift,
It can be stated mathematically as a Doppler shift,
fD = (v/lambda) * cos(theta),
where v is the user's velocity and lambda is the operating frequency's wavelength. And theta = angle between BS and MS (theta)
🔍 Want a deeper explanation? Doppler Shift Equation & Examples → Interactive Doppler Simulator →
3G
The 3G connection became accessible later in 2001. 3G was the first wireless upgrade to bring online multimedia, video conferencing, and other features to the market. A 3G connection proved sufficient for internet video streaming. The main motivation behind 3G technology was to overcome the bandwidth limitation of 2G. WCDMA, CDMA2000, UMTS, etc. were the most popular 3G access technologies at that time. Primarily, 3G was able to handle a data transfer rate of 3.5 Mbps. Later on, we see different extensions of the third-generation network, like, HSDPA, HSUPA, HSPA+, etc.
4G
In 4G, we observe data speeds of 30-40 Mbps that are satisfactory. However, the number of internet-connected devices is growing every day. 4G was designed to handle a data transfer rate of 300Mbps along with QoS (quality of service). According to Cisco, there will be 50 billion gadgets linked to the internet worldwide by 2020.
As a result, more bandwidth is required to connect more devices to the BS at the same time, and the need for high data rates is increasing. We are now accustomed to learning from video rather than text, such as high-definition video streaming, video conferencing, and so on. These applications necessitate a high data transfer rate.
4G is currently experiencing bandwidth congestion. The amount of data traffic generated by various wireless devices is increasing every day. So, either modern 4G is incapable of managing it, or the bandwidth of recent 4G LTE is insufficient to connect all devices to the internet at the same time. More bandwidth is required. 5G can help us with this.
5G
5G will, as we well know, operate at incredibly high frequencies ranging from sub 6 GHz band to millimeter wave band (26 to 100 GHz). It has a large spectrum of resources. Extremely high frequencies, massive MIMO, and beamforming are crucial 5G technologies that will address future telecom network needs or demands. Read More about 5G in detail...
That are also key technologies for 6G, and beyond. Sub-terahertz frequencies are expected to be used for 6G.
Explore 5G Technologies
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[1] Wireless Communication Projects/Thesis Ideas
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#how cellular communication is different from radio communication?
What is the communication method that uses symbolic codes for data transmission?
A. Telegraphy. It uses Morse code.