Why is LTE not 4G?
The last few years is the rapid development and implementation of Long Term Evolution (LTE) standard networks. Large and not very mobile operators around the world are actively promoting this technology as a fourth-generation (4G) communication technology. Is LTE really 4G technology? The answer to this question is below.
To begin, briefly recall what happened to LTE and how mobile communications developed. The figure below will help us with this.
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It all began on the border of the 70s and 80s of the 20th century. At this time, the first analogue mobile communication systems (APMS, NMT-450, TACS) were developed in several countries (USA, Japan, Northern Europe). These technologies are usually attributed to the first generation (1G). The first network that was launched into commercial operation was the APMS standard network and this was in Chicago.
In about 10 years, second-generation digital mobile communication systems (2G) have already been developed. The most famous of these are CDMA and GSM technologies. CDMA technology is based on code division channels, and GSM technology is based on time. However, both are circuit switched technologies. And they were developed for voice. In order to transmit various data using packet switching, and to increase the efficiency of using radio resources, GPRS and EDGE add-ins were developed.
The next stage in the development of mobile communication systems is the emergence of representatives of the third generation (3G), namely the UMTS standard. UMTS technology has increased the speed of data transmission, and from the very beginning supported both circuit switching and packet switching. Further development of this technology (HSPA) provides an even greater increase in data transfer speeds (up to ~ 30 Mbps).
And here comes the LTE technology. And today there is already its continuation in the form of LTE-Advanced (LTE-A). To which generation do these technologies belong and how do they differ from each other? Let's figure it out.
It's all very simple. There is an international telecommunications union called ITU (International Telecommunications Union). It is this union that defined the requirements for fourth-generation networks. The list of requirements is called IMT-Advanced (International Mobile Telecommunication-Advanced).
The main requirements include: peak spectral efficiency, supported width of the radio channel and data transmission delay. As the values of these characteristics, which the fourth generation systems should have, the following were chosen:
- peak spectral efficiency: downlink (from base station to subscriber) 15 bit / s / Hz; uplink (from subscriber to base station) 6.75 bps / Hz
- supported channel width: up to 40 MHz
- data transmission delay: not in a loaded system should not exceed 10 ms.
Does LTE technology meet these requirements?
LTE specifications:
- peak spectral efficiency: downlink 16 bit / s / Hz (with MIMO 4x4); uplink 4 bps / Hz
- supported channel width: up to 20 MHz
- data transmission delay: ~ 5 ms.
As we can see, LTE fully meets only the delay requirements for fourth-generation systems. The requirements of neither spectral efficiency, nor supported channel width imposed on 4G technology LTE does not respond. Accordingly, it can not be attributed to the technology of the fourth generation. All claims that LTE is 4G should be considered as a purely marketing move and nothing more.
What then is 4G technology? Let's look at the very characteristics of LTE-Advanced technology:
- peak spectral efficiency: downlink 30 bps / Hz (with MIMO 8x8); uplink 16.1 bps / Hz (with MIMO 4x4)
- supported channel width: up to 100 MHz
- data transmission delay: ~ 5 ms.
This is the real 4G!
Due to what is LTE-A able to achieve such indicators? The main reasons are the use of the following technologies:
- an increase in the number of transmitting and receiving antennas up to 8 on each side (MIMO 8x8)
- Carrier Aggregation - the union of frequency channels, the total width of which can reach 100 MHz
- Coordinated Multipoint (CoMP) transmission / reception - service of one subscriber by several base stations
- HetNet - heterogeneous networks, the use of pico- and micro-base stations.
About each of these methods you can write more than one article. If there are interested readers, I will try to briefly highlight them in my next work.
That's all for now. Thanks for attention.
PS If someone finds this note worthy of an invitation - I will be very grateful.
A bit of history
To begin, briefly recall what happened to LTE and how mobile communications developed. The figure below will help us with this.
')
It all began on the border of the 70s and 80s of the 20th century. At this time, the first analogue mobile communication systems (APMS, NMT-450, TACS) were developed in several countries (USA, Japan, Northern Europe). These technologies are usually attributed to the first generation (1G). The first network that was launched into commercial operation was the APMS standard network and this was in Chicago.
In about 10 years, second-generation digital mobile communication systems (2G) have already been developed. The most famous of these are CDMA and GSM technologies. CDMA technology is based on code division channels, and GSM technology is based on time. However, both are circuit switched technologies. And they were developed for voice. In order to transmit various data using packet switching, and to increase the efficiency of using radio resources, GPRS and EDGE add-ins were developed.
The next stage in the development of mobile communication systems is the emergence of representatives of the third generation (3G), namely the UMTS standard. UMTS technology has increased the speed of data transmission, and from the very beginning supported both circuit switching and packet switching. Further development of this technology (HSPA) provides an even greater increase in data transfer speeds (up to ~ 30 Mbps).
And here comes the LTE technology. And today there is already its continuation in the form of LTE-Advanced (LTE-A). To which generation do these technologies belong and how do they differ from each other? Let's figure it out.
4G requirements
It's all very simple. There is an international telecommunications union called ITU (International Telecommunications Union). It is this union that defined the requirements for fourth-generation networks. The list of requirements is called IMT-Advanced (International Mobile Telecommunication-Advanced).
The main requirements include: peak spectral efficiency, supported width of the radio channel and data transmission delay. As the values of these characteristics, which the fourth generation systems should have, the following were chosen:
- peak spectral efficiency: downlink (from base station to subscriber) 15 bit / s / Hz; uplink (from subscriber to base station) 6.75 bps / Hz
- supported channel width: up to 40 MHz
- data transmission delay: not in a loaded system should not exceed 10 ms.
Does LTE technology meet these requirements?
LTE and LTE-A technologies
LTE specifications:
- peak spectral efficiency: downlink 16 bit / s / Hz (with MIMO 4x4); uplink 4 bps / Hz
- supported channel width: up to 20 MHz
- data transmission delay: ~ 5 ms.
As we can see, LTE fully meets only the delay requirements for fourth-generation systems. The requirements of neither spectral efficiency, nor supported channel width imposed on 4G technology LTE does not respond. Accordingly, it can not be attributed to the technology of the fourth generation. All claims that LTE is 4G should be considered as a purely marketing move and nothing more.
What then is 4G technology? Let's look at the very characteristics of LTE-Advanced technology:
- peak spectral efficiency: downlink 30 bps / Hz (with MIMO 8x8); uplink 16.1 bps / Hz (with MIMO 4x4)
- supported channel width: up to 100 MHz
- data transmission delay: ~ 5 ms.
This is the real 4G!
Due to what is LTE-A able to achieve such indicators? The main reasons are the use of the following technologies:
- an increase in the number of transmitting and receiving antennas up to 8 on each side (MIMO 8x8)
- Carrier Aggregation - the union of frequency channels, the total width of which can reach 100 MHz
- Coordinated Multipoint (CoMP) transmission / reception - service of one subscriber by several base stations
- HetNet - heterogeneous networks, the use of pico- and micro-base stations.
About each of these methods you can write more than one article. If there are interested readers, I will try to briefly highlight them in my next work.
That's all for now. Thanks for attention.
PS If someone finds this note worthy of an invitation - I will be very grateful.
Source: https://habr.com/ru/post/175493/
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