LTE (Long Term Evolution) is a long-term evolution technology of the UMTS (Universal Mobile Telecommunications System) technology standard developed by the 3GPP (The 3rd Generation Partnership Project) organization, which was officially established and launched in It was formally established and launched at the 3GPP Toronto meeting in December 2004.
The LTE system introduces key technologies such as OFDM (Orthogonal Frequency Division Multiplexing) and MIMO (Multi-Input & Multi-Output).
Significantly increased the spectral efficiency and data transmission rate (20M bandwidth 2X2MIMO in the case of 64QAM, the theoretical maximum downlink transmission rate of 201Mbps, after removing the signaling overhead is about 150Mbps, but according to the actual network and terminal capacity limitations.
It supports various bandwidth allocations: 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz, and 20MHz, etc. It also supports global mainstream 2G/3G bands and some new bands, thus making the spectrum allocation more flexible and the system capacity and coverage significantly improved.
LTE was born to continuously optimize wireless communication technology to meet the higher requirements of customers for wireless communication.
LTE is a standard for wireless data communication technology, and the current goal of LTE is to enhance the data transmission capability and data transmission speed of wireless networks with the help of new technologies and modulation methods.
The long-term goal of LTE is to simplify and redesign the network architecture to make it IP-based, which helps to reduce the potential undesirable factors in 3G conversion.
LTE technology mainly exists in two mainstream modes, TDD and FDD, and each of the two modes has its own characteristics. Among them, FDD-LTE is widely used internationally, while TD-LTE is more common in China.
LTE (Long Term Evolution) project is the evolution of 3G, a transition between 3G and 4G technology, and is the global standard of 3.9G. It improves and enhances the 3G air access technology, using OFDM and MIMO as the only standard for the evolution of its wireless network.
It offers peak rates of 100Mbit/s downlink and 50Mbit/s uplink in 20MHz spectrum bandwidth, improving cell edge user performance, increasing cell capacity, and reducing system latency.
What is LTE development history?
At the end of 2004, the standardization work of LTE was started in 3GPP. Unlike 3G, which is based on CDMA technology, according to the trend of wireless communication towards broadband, LTE adopts OFDM technology as the basis and combines the design concepts of multiple antennas and fast packet scheduling, forming a new air interface technology for the next-generation mobile communication system, which is also called 3G evolutionary system.
At the beginning of 2008, the first version of the LTE system technical specification was completed, namely, Release 8. While LTE technology research was conducted in 3GPP, the International Telecommunication Union (ITU) has been carrying out research work on market demand and frequency planning of next-generation mobile communication systems, in preparation for the development of international standard recommendations for 4G technology.
In March 2008, the ITU started the process of soliciting and standardizing candidate technologies, called IMT-Advanced, and in response to the ITU’s call for 4G IMT-Advanced technology, the 3GPP called LTE-Advanced for the LTE Release10 and later versions of the technology understudy and submitted the candidate technologies to the ITU. The submission of the
Voice call LTE supports both FDD and TDD duplex mode, in the LTERelease8 version, using 20MHz communication bandwidth, the peak downlink rate of the air interface exceeds 300Mbit/s peak rate of the uplink direction also exceeds 80Mbit/s.
As a subsequent evolution of TD-SCDMA technology, the TDD mode of LTE is also called TD-LTE/TD-LTE-Advanced.
Out of concern for the evolution route of TD-SCDMA technology, Chinese member units are deeply involved in the relevant system design process in 3GPP, and in October 2009, the Chinese government formally submitted TD-LTE-Advanced proposal to ITU as a candidate technology for 4G international standard.
What is LTE technical architecture?
LTE network structure and air interface protocol: LTE adopts a single-layer structure composed of Node B, which is conducive to simplifying the network and reducing the delay, and realizing the requirements of low delay, low complexity, and low cost.
Compared with the traditional 3GPP access network, LTE reduces the number of RNC nodes and changes the whole architecture of 3GPP, gradually converging to the typical IP broadband network structure. Or it is called the Evolved UTRAN Architecture (E-UTRAN).
What is LTE technical objectives?
The technical objectives of LTE can be summarized as follows.
Capacity enhancement: to reach a peak downlink rate of 100Mbit/s and a peak uplink rate of 50Mbit/s at a bandwidth of 20MHz. spectrum utilization of 2 to 4 times the planned value of 3GPP R6.
Coverage enhancement: increase the cell edge bit rate to meet the optimal capacity in the 5km area, with a slight decrease in the 30km area, and support a coverage radius of 100km.
Mobility enhancement: optimal performance from 0 to 15km/h, high performance from 15 to 120km/h, support for 120 to 350km/h. Even support for 500km/h in some frequency bands.
Quality optimization: less than 10ms delay at the RAN user plane and less than 100ms delay at the control plane.
Integrated service content diversification: provide high-performance broadcast service MBMS, improve real-time service support capability, and enable VoIP to reach UTRAN circuit domain performance.
O&M cost reduction: Adopting a flat architecture can reduce CAPEX and 0PEX, and reduce the cost of evolving from R6 UTRA airports and network architecture.
What is LTE core technology?
What is LTE SC-FDMA technology?
SC-FDMA technology is a single-carrier multi-user access technology that is simpler to implement than OFDM/OFDMA but has inferior performance to OFDM/OFDMA. SC-FDMA has a lower PAPR compared to OFDM/OFDMA.
Higher transmitter efficiency improves network performance at the cell edge. The biggest benefit is the reduced peak-to-average power ratio of the transmitter terminal, reduced terminal size and cost, which is one of the main reasons for choosing SC-FDMA as the LTE uplink signal access method.
Its features also include flexible spectrum bandwidth allocation, fixed subcarrier sequences, the use of cyclic prefixes to combat multipath fading, and variable transmission intervals.
What is LTE OFDM technology?
The main feature of the OFDM technology LTE system, its basic idea is to spread the high-speed data stream to multiple orthogonal subcarriers for transmission, so that the symbol rate on the subcarrier is greatly reduced, the symbol duration is greatly lengthened, and thus has a strong resistance to delay expansion, reducing the impact of inter-symbol interference.
Usually in OFDM symbols before the addition of protection interval, as long as the protection interval is greater than the delay expansion of the channel can completely eliminate inter-symbol interference ISI.
What is LTE MIMO technology?
MIMO is the most important means to improve the system transmission rate but also received a lot of attention. Due to the relatively flat subcarrier fading of OFDM, it is very suitable for combining with MIMO technology to improve system performance.
MIMO systems use multiple antennas or (array-contracted antennas) and multiple channels at both the transmitter and receiver sides. Multi-antenna receivers use space-time coding processing to be able to separate and decode data sub-streams for optimal processing.
If the channel response between each transmits and receive antenna is independent, the multiple-in and multiple-out system can create multiple parallel spatial channels. By transmitting information independently through these parallel spatial channels, data rates can certainly be increased.
MIMO optimizes multipath wireless channels with transmitting and receiving as a whole, thus achieving high communication capacity and spectrum utilization.
It is a near-optimal joint air-domain time-domain diversity and interference-cancellation processing. When the power and bandwidth are fixed, the maximum capacity or upper capacity limit of the multiple-input multiple-output system increases linearly with the minimum number of antennas.
While under the same conditions, the capacity of the ordinary smart antenna system with multiple antennas or antenna arrays at the receiver or transmitter side only increases with the logarithmic increase in the number of antennas.
What is LTE high-order modulation technique?
LTE uses QPSK, 16QAM, and 64QAM in the downlink direction and QPSK and 16 deletions in the uplink direction. The high peak transmission rate is the main problem to be solved for LTE downlink.
In order to achieve the system downlink 100Mb/s peak rate target, based on the original QPSK and 16QAM of 3G, the LTE system adds 64QAM high-order modulation.
What is LTE branching?
With the evolution and development of technology, 3GPP has successively proposed TD-LTE, FDD-LTE, and other technologies.
What is TD-LTE technology?
TD-LTE is a new generation of broadband mobile communication technology, which is the subsequent evolution technology of TD-SCDMA with China’s independent intellectual property rights, inheriting the advantages of TDD while introducing multi-antenna MIMO and frequency division multiplexing OFDM technology.
Compared with 3G, TD-LTE has leaps and bounds improvement in system performance and can provide users with more colorful mobile Internet services.
What is FDD-LTE technology?
FDD (Frequency Division Duplexing) is one of the two duplex modes supported by the technology, and the LTE with FDD application is FDD-LTE. due to the difference in wireless technology, the difference in the frequency band, and the interest of each manufacturer, the standardization and industrial development of FDD-LTE are ahead of TDD-LTE.
FDD mode is characterized by the system receiving and transmitting on two symmetrical frequency channels separated (upstream and downstream frequency interval of 190MHz), with guaranteed frequency bands to separate the receiving and transmitting channels.
The advantage of FDD mode is the use of packet switching and other technologies, which can break through the bottleneck of second-generation development and realize high-speed data services, and can improve spectrum utilization and increase system capacity.
However, FDD must use paired frequencies, i.e., provide third-generation services in every 2 x 5 MHz of bandwidth. This approach can make full use of the spectrum in the upstream and downstream when supporting symmetric services.
When working with asymmetric packet switching (Internet), the spectrum utilization is much lower (about 40% lower due to low uplink load). In this respect, TDD mode has an advantage that FDD cannot match.
What is LTE frequency band？
LTE networks are available in a considerable number of frequency bands, and the choice of frequency bands varies from region to region.
North American networks are planned to use 700/800 MHz and 1700/1900 MHz.
European networks are planned to use 800 MHz, 1800 MHz, and 2600 MHz.
Asian networks plan to use 1800 MHz and 2600 MHz.
The Australian network is planned to use 1800 MHz.
Therefore, it is likely that a terminal used normally in one country will not work in the network of another country, and users need to use terminals supporting multiple frequency bands for international roaming.
In particular, the Brazilian government is working with local operator CPqD, which is testing a special LTE network. The network needs to be created in a band below 450 MHz due to adaptation to local market demand.
It is likely that the end of the network in another country will not be available, and users will need to use terminals that support multiple frequency bands for international roaming.
In particular, the Brazilian government is working with local operator CPqD, which is testing a special LTE network. The network needs to be created in a band below 450 MHz to meet local market demand.
What is LTE development trend?
LTE technology has played a very important role in the transition from 3G technology to B3G and 4G.
Before B3G and 4G technology completely replace 3G technology, LTE technology will undoubtedly continue to play its own important role in further enhancing the transmission rate of the 3G communication networks and reducing the data transmission delay.
LTE technology, as one of the tools to enhance the data transmission rate of 3G communication networks, has achieved remarkable results. According to the survey, the current uplink data transmission rate of LTE can reach up to 500MB/s, and the downlink data transmission rate can already reach 1Gbit/s.
However, LTE still shows great room for operation in terms of improving the information transmission rate. The application of MIMO technology with LTE technology will make LTE technology more excellent, and LTE’s data transmission rate and the anti-interference ability of the external signal will be further improved.
With the advent of the global information age and the spread of the trend of the explosive growth of data, the communication network data transmission rate will not stop.
Therefore, even after B3G and 4G technologies have achieved certain results, LTE technology will still play an important guiding role in optimizing the transmission performance of the entire network.
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