Three 3G mobile telecommunication companies entered `speed competition` to increase communication speed to 4G LTE technology Before the commercialization of 5th generation (G) mobile communication network with more than 20Gbps within 2020.

3 main mobile carriers have achieved the highest download speed of 300Mbps with `LTE-A (Advanced)` by applying Carrier Aggregation (CA) technology to LTE in 2013, and the download speed to a level up to 1 Gbps. It means that mobile communication speeds are three times faster than in 2013 which is four years later.

SK Telecom, KT, LG U Plus and other three mobile carriers have been competing with each other to increase the speed of mobile communication network. Mobile carriers have first commercialize LTE with a download speed of 75Mbps in 2011, and in 2013, they bundled two different frequency bands together to boost speed up to 150Mbps by using CA technology, which can be used as a single wide frequency. Besides, in 2015, the three-band CA bundling the three frequency bands raised the speed up to 300Mbps. Since then, carriers have applied the 256 × (QAM) base station technology, which improves the frequency efficiency by 33% until 2016, and the 4 × 4 MIMO antenna technology, which doubles the LTE speed and it has been put it up to 500Mbps.


Mobile carriers are expected to increase speed more with the launch of the Samsung Galaxy S8. The Galaxy S8 supports 5-band CAs bundling up to five frequencies with four, which can boost download speeds comparing to existing handsets that supported 3-band CA,

SK Telecom was first to fire up the speed competition. The company has stated on April 20 that it applied `5-band CA` technology that uses 5-width frequency in 4 frequency bands in mid-May, and download speed is 700Mbps and `4 × 4 mimo` technology is applied simultaneously to `4-band CA`. The company also plans to increase the speed to 900Mbps by applying 2 `4 × 4 mimo` technology to a 3-band CA in the first half of next year.

SK Telecom currently has LTE frequencies including 20 MHz bandwidth in the 800 MHz band, 35 MHz band (broadband) in the 1.8 GHz band, 20 MHz band in the 2.1 GHz band, and 60 MHz band (broadband) in the 2.6 GHz band. The company utilizes five frequencies for the 5-band CA technology: the 800 MHz bandwidth of 0 MHz, the 1.8 GHz band of 20 MHz, the 2.1 GHz band of 10 MHz, the 2.6 GHz band of 20 MHz, and the 10 MHz bandwidth. Generally, the maximum download speed is 75 Mbps at the narrow band frequency of 10 MHz. By using the 256 QAM technology that increases the speed up to 33%, the speed of about 100Mbps in the narrow band and 200Mbps in the wide band also comes out. As a result, using SK Telecom`s five frequencies, the download speed can theoretically be increased to 700Mbps. 4-band CA and 4 × 4 mimic technology can also be used to achieve speeds of up to 800 Mbps accordingly. In the case of applying two 4 × 4 mimo technologies to a 3-band CA, the company can bundle one of three narrow bands at 1.8GHz and 2.6GHz for broadband and 900Mbps for 2 broadband and 4 × 4 MIMO.

A company representative explained, ‘There is currently a limit to combining CA and 4 × 4 mimic technology, so it can only be up to 900Mbps Due to the technical limitations of handsets and base station software.’ When Samsung Electronics and Qualcomm launch next year`s upgraded chipsets, the speed can be faster over 1Gbps’.

KT may bundle four frequencies: 900MHz and 1.8GHz (one broadband, one narrowband) and 2.1GHz. According to KT, the maximum download speed of 300Mbps is available for a 3-band CA, but it can be up to 500Mbps for a 4-band CA and can be increased to 700Mbps for 4 × 4 mimosa technology in one broadband frequency. On the other hand, LG U Plus has three bands including LTE frequency band of 800MHz, 2.1GHz and 2.6GHz, therefore, it is difficult to apply 4-band CA technology. Instead, it has broadband frequencies of 40MHz bandwidth in 2.1GHz and 2.6GHz band. The company plans to increase communication speed by applying 256 QAM and 4 4 x 4 mimic technology to dual 3-band CA that uses it.

By Na Won Jae nwj@


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