What does TD-SCDMA mean?

TD-SCDMA[ 1], as the third generation mobile communication standard proposed by China, was formally submitted to ITU (International Telecommunication Union) from 1998. This standard has been evaluated by experts, approved and issued by ITU, integrated with 3GPP (3rd generation partnership project) system and introduced with new technical features for more than ten years. As a result, TD-SCDMA [3] standard became the first international standard for wireless communication proposed by China, mainly based on China's intellectual property rights, and was widely accepted and recognized internationally. This is an important milestone in the telecom history of China. (Note: 3G has four international standards, and the other three are CDMA2000 led by the United States, WiMAX and WCDMA led by Europe. )

[Edit this paragraph] Overview of ]TD-SCDMA technology

Time division-synchronous code division multiple access (TD-SCDMA) is one of the three 3G standards approved by ITU, which started later than the other two major 3G standards (CDMA2000 or WCDMA).

This standard is a 3G standard formulated by China. 1On June 29th, 999, the former Institute of Telecommunications Science and Technology of China Ministry of Posts and Telecommunications (now Datang Telecom Technology Co., Ltd.) proposed the standard to ITU. This standard integrates smart antenna, synchronous CDMA and SDR. In addition, due to the huge communication market in China, the standard has attracted the attention of major telecom equipment manufacturers, and more than half of the equipment manufacturers in the world have announced that they can produce telecom equipment supporting TD-SCDMA standard.

TD-SCDMA has unique advantages in spectrum utilization, business support flexibility, frequency flexibility and cost.

TD-SCDMA adopts time division duplex, and the uplink and downlink channel characteristics are basically the same. Therefore, it is easier for the base station to estimate the uplink and downlink channel characteristics from the received signals. In addition, TD-SCDMA has inherent advantages in using smart antenna technology, which introduces the advantages of SDMA, which can reduce the interference between users and improve the spectrum utilization.

TD-SCDMA also has the advantages of TDMA, which can flexibly set the ratio of uplink and downlink time slots and adjust the ratio of uplink and downlink data rates, and is especially suitable for occasions with less uplink data and more downlink data in Internet services. However, the variability of uplink and downlink switching points increases the complexity of co-frequency networking.

TD-SCDMA is time division duplex, and it doesn't need paired frequency bands. Therefore, compared with the other two 3G standards of frequency division duplex, it is more flexible in the division of frequency resources.

It is generally believed that TD-SCDMA can greatly simplify the complexity of the system by adopting smart antenna and synchronous CDMA technology, and is suitable for adopting software radio technology, so the equipment cost is expected to be lower.

However, due to the shortcomings of the time division duplex system, TD-SCDMA is considered to lag behind the frequency division duplex system in terms of terminal allowable moving speed and cell coverage radius.

At the same time, TD can only have 500 people online, which is a problem.