3G Technology | Third-generation mobile communications system enabling high-speed digital communications

Japanese domestic method

In Japan, NTT Docomo and Softbank use WCDMA, while au uses CDMA2000 (1x).
Rakuten Mobile began its service as an MNO (Mobile Network Operator) in October 2019, and therefore prioritized expanding its LTE and 5G area coverage and did not adopt 3G.

What is CDMA?

Code Division Multiple Access is a method of communication in which a different spread spectrum code is assigned to each terminal using one main frequency. Because the spread codes are different, even if multiple terminals communicate on the same frequency at the same time, it is possible to identify the channel for each terminal, resulting in higher frequency utilization efficiency.

Bandwidth Usage

WCDMA uses the allocated band as is.
CMDA2000 uses three carrier waves and divides them into three for communication. 1x means that communication is performed using only one of the three divided carrier waves, and 3x means that communication is performed using all three of the three divided carrier waves simultaneously.

• WCDMA

  

• CDMA2000 (1x)

  

• CDMA2000 (3x)

  

Simultaneous use of data and voice

WCDMA transmits multiple data communications data, voice data, and other data together on a single channel over a large bandwidth. Therefore, if either data is too large, communication speeds and voice quality may decrease.
CDMA2000 (1x) uses separate bands for voice and data, so quality can be guaranteed, but since it only uses one channel, you can only use either voice or data.

HSPA

By keeping the signal strength constant and sending more data to devices with good signal strength and less data to devices with poor signal strength, and by closely checking changes in the device's status and adjusting the amount of data, we were able to efficiently use the signal and increase the overall amount of data.The four main elemental technologies are as follows.

HSPA+

HSPA Evolution was developed to achieve download speeds of up to 20Mbps. It uses 64QAM modulation to achieve download speeds of up to 21Mbps. Speeds can be increased simply by updating the software.

DC (Dual-Cell)-HSDPA

HSDPA is a method of using two adjacent bands during peak communication times, instead of the 5MHz band used in previous versions, allowing communication speeds up to twice as fast. Except for band management, the technology is the same as HSPA+.

EV-DO (Rev.0)

This technology optimizes data communications to significantly improve downstream throughput. There are three main elemental technologies:

EV-DO (Rev.A)

It increases the upstream transmission speed and realizes QoS (Quality of Service) functionality.

EV-DO multi-carrier

This technology enables faster data transmission by using up to three EV-D Rev.A carriers (carrier waves) simultaneously. Data transmission and reception can be made more efficient, resulting in communication speeds up to three times faster than EV-DO Rev.A.