Recently, South Korean telecom operator SK Telecom announced the official launch of tri-band LTE-A commercial, and Samsung officially released the first smartphone supporting LTE-A Tri-Band CA: Galaxy Note 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 of the 3G system, 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.
1. 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, it can support various systems of 1.4, 3, 5, 10, 15 and 20 MHz. 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. High-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 (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.
The wind is rising, the LTE-A tide has arrived
South Korea's LTE-A three-band carrier aggregation technology has opened up a turbulent LTE-A tide for domestic people who have not yet understood TDD and FDD.
LTE users are showing tremendous data traffic consumption. Data show that in the first four months of 2014, the average data usage of LTE users in Hong Kong was almost twice that of 3G users. In 2013, US operator Verizon announced that 57% of mobile data traffic in the network was transmitted by LTE. The data traffic consumption mining for 4G users is consistent with the direction in which operators should maintain a high degree of “pipelined†crisis.
But another fact that stuns operators is that WiFi still plays an important role in taking on the rapidly increasing data demands of users. In all major LTE markets, WiFi data still accounts for 75%-90% of the total mobile data. In other words, the user's data demand is rapidly increasing, but the 4G network with greatly increased capacity does not fully show the shunting effect of large data traffic processing in most cases.
In the case of high-speed rail, you can better understand the taste. The high-speed rail was noisy for a long time, and finally found that the big guys were going to take the train, or choose the plane from a long distance. With the advancement of high-speed rail technology, the high-speed rail decided to launch the high-speed sleeper high-speed rail and intercity high-speed rail.
With the acceleration of the LTE-A commercial process and the technical cost advantage, the deployment of LTE-A network in 2014 has been strongly promoted by operators. According to GSA statistics, as of October 2014, 21 operators in 14 countries around the world have launched LTE-A commercial networks based on carrier aggregation technology, including Japan, South Korea, the United States, France, etc., and more than 79 The operator is conducting network deployment or testing.
The LTE-A commercial process, led by Hong Kong and South Korea, has gradually accelerated in the near future. As the most aggressive country for LTE-A commercial network promotion, the three major operators in South Korea have launched LTE-A services based on carrier aggregation. The country already has nearly 210,000 LTE-A base stations, accounting for 47% of the number of LTE base stations. Half of the LTE base stations have been upgraded to LTE-A base stations!). In December 2014, Singapore Telecom Operators First Link (M1) and Singapore Telecom (SingTel) intensively announced the opening of commercial LTE-A network, promising that all 4G customers with compatible equipment will be able to use LTE-A services at no additional charge. Telstra announced the launch of LTE-A commercial; meanwhile, Saudi Arabian operator STC launched the world's only TDD LTE-A network.
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