Although 5G is still far away, the industry has started to explore 5G long time ago. it is widely believed that 5G will achieve scale commercialization in 2020. However, this doesn’t prevent the continuous evolution of the network. The first and key step during evolution of 4G/LTE network to LTE-Advanced network is the adoption of carrier aggregation (CA), namely improving the spectrum bandwidth by increasing the LTE channels.
In fact, as a network technology, CA has been widely used in the existing networks, the current commercial networks generally support dual-CA. However, by the driving of consumer demands, the devices have overcome inter band interferences, power consumption standby time and other difficulties, the triple-CA supporting Cat.9 commercial devices have already appeared on the market and the downlink rate can reach up to 450Mbps.
At present, diversified devices on the market support Cat.4 and Cat.6 dual-CA and the maximum downlink rate can reach 150Mbps and 300Mbps, respectively. In addition, many flagship models began to support Cat.9, such as Xiaomi Note Top version, LeTV Le One pro and others. It’s expected that more and more devices that support Cat.9 or even higher level LTE connection function will appear in the next year.
The appeals of consumers are passed to the network through devices. During large-scale construction of 4G networks, China's three major telecom operators have also launched the CA evolution plans. Take China Mobile for example, the current commercial networks are dual-CA of 1.9GHz + 2.6GHz and 2.3GHz + 2.3GHz frequency bands, it may also deploy the triple-CA in the next year. Recently, China Mobile cooperated with Ericsson and demonstrated the first TD-LTE downlink triple-CA technology that integrated with 256QAM modem technology, and the downlink peak rate reached 426Mbps. In the previous time, China Mobile cooperated with ZTE and Qualcomm and jointly conducted triple-CA trail in Guangzhou.
After the introduction of 4G+ strategy, China Telecom has aggressively promoted the commercialization of CA technology. The 4G+ strategy mainly tests the dual-CA of 800MHz+1.8GHz/2.1GHz and 1.8GHz+2.1GHz frequency bands. Recently, China Telecom completed the triple-CA technology validation with Huawei and Qualcomm, with the device equipped with Qualcomm Snapdragon processor and Huawei commercial base station, it achieved triple-CA of 1.8GHz (20 MHz) + 2.1GHz (20 MHz) + 800MHz (10MHz) frequency bands, the downlink peak rate reached 371Mbps and was close to the theor speed. China Unicom has conducted the triple-CA tests in last year, with the network construction focus turned to 4G, CA commercialization process will also speed up.
According to the public data, 88 operators have deployed CA in the world by July 2015, 25 operators have been researching, testing and deploying systems that support Cat 9 devices (peak rate of 300Mbps to 450Mbps). With the driving of consumer demands and maturity of device and chip industries, the triple-CA tests and commercialization will definitely speed up in the next year.
