SKTelecom, the fifth-generation communication network technology called "tri-band LongTerm EvoluTIon-Advanced" (hereinafter referred to as LTE-A), is the fourth-generation communication network "Long Term EvoluTIon" (hereinafter referred to as Next generation network of LTE).
When the country is still arguing over when to issue FDD licenses, Smect has envied the world with the speed of the Internet.
Recently, South Korean telecom operator SK Telecom announced the official launch of the three-band LTE-A commercial, while Samsung officially released the first LTE-ATri-BandCA-enabled smartphone: GalaxyNote 4 LTE-A. In fact, as early as January this year, SK Telecom announced the successful development of the world's first "LTE-A three-band carrier aggregation" technology. The Galaxy Note 4 LTE-A is equipped with Qualcomm's latest 64-bit Snapdragon 810 processor and integrated LTE-A Cat.9 modem, marking the maturity of the corresponding chipsets and devices for the tri-band LTE-A commercial.
Prior to this, carrier aggregation has achieved two frequency bands. Hong Kong Mobile Communications (CSL) achieved the highest 20MHz+20MHz in September last year. Koreans have achieved carrier aggregation for three bands for the first time, specifically 20MHz+10MHz+ 10MHz, although it seems that the sum of the frequency bands is similar, the theoretical maximum download rate is also up to 300Mbps (calculated, it takes only 19 seconds to download a 1GB movie), but the three-band carrier aggregation represents a more complicated technological breakthrough.
Technical characteristics of LTE-A
What is LTE-A? Some reports refer to SK Telecom's commercial tri-band LTE-A as the fifth-generation communication, which is actually a deviation from LTE-A and LTE.
Strictly speaking, LTE-A is a further evolution of LTE technology. At the Quebec meeting in November 2004, 3GPP determined the long-term evolution plan for the 3G system (LongTermEvoluTIon), which was later known as LTE. In March 2008, the International Telecommunication Union (ITU) basically completed the standardization of LTE. The first two versions of LTE, Release8 and Release9, do not meet the ITU's peak requirement of 1Gbit/s for 4G, which is generally called 3.9G or quasi-4G. Since then, the LTE R10 based on R8/R9 has merged with the new technology architecture to truly meet the peak rate requirements of the ITU. The LTE R10 and subsequent versions are called LTE-Advanced (LTE-A). 4G. In January 2012, the ITU adopted LTE-A as one of the 4G technologies, and LTE R12 is currently undergoing standard certification.
LTE-A is not an independent technology, but a set of technologies consisting of carrier aggregation, high-order MIMO, enhanced inter-cell interference coordination, and relaying in R10 and subsequent standards.
Carrier aggregation
The spectrum resources are always limited, especially in the market environment of network traffic blowout. To achieve the high peak requirement of LTE-A, the most direct way is to increase the transmission bandwidth. Carrier aggregation is designed to aggregate multiple consecutive or discrete narrow-bandwidth carriers to form a wider complete spectrum, which not only meets the higher system bandwidth requirements of LTE-A systems, but also effectively utilizes fragmentation. Spectrum resources.
LTE adopts OFDM multiple access technology to transmit high-speed data streams through serial-to-parallel conversion, and allocates frequency resources in units of sub-carriers. According to different number of sub-carriers, various systems of 1.4, 3, 5, 10, 15 and 20 MHz can be supported. Bandwidth, the maximum transmission bandwidth is 20MHz. By aggregating multiple backward compatible LTE carriers, LTE-A supports simultaneous aggregation of up to 5 carriers to achieve a transmission bandwidth of 100 MHz. The terminal equipment of the LTE-A can access multiple carriers or normally access one LTE carrier to work.
It can be said that carrier aggregation is the basis of the large bandwidth operation of the LTE-A system, and is an important component of LTE-A and the focus of attention. For operators, carrier aggregation technology determines whether a "peak rate advantage" can be achieved. SK Telecom's tri-band LTE-A can be understood as achieving simultaneous aggregation of three LTE carriers.
2. Higher order MIMO
High-order MIMO technology is another key technology for improving throughput of LTE systems, and it is also one of the representative technologies of 4G. By using multiple antennas at the transmitting end and the receiving end, the capacity and spectrum utilization of the communication system are doubled without increasing the bandwidth. The Release 8 version supports up to 4 data streams for parallel transmission and achieves peak rates in excess of 300 Mbit/s at 20 MHz bandwidth. LTE-A downlink transmission is extended from LTE's 4 antennas to 8 antennas, and supports up to 8 layers and two codeword streams. In 2011 and 2012, R10 and R11 respectively, the downlink peak rate can be increased to 3Gbit/s. The downlink peak spectral efficiency can be increased to 30 bit/s/Hz.
3. Wireless relay technology
The traditional base station needs to provide a wired link connection at the site for "backhaul transmission", and the relay station performs backhaul transmission on the network side through the wireless link, which is small in size, light in weight, and easy to locate. With the relay forwarding of the relay station, the network coverage can be extended to areas outside the cell and other coverage blind areas. At the same time, by reducing the signal propagation distance, the data throughput of the hotspot area is effectively improved, and the network quality is ensured.
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