Comprehensive introduction to WCDMA technology in Wireless Access Networks

The application of wireless access networks is still very extensive. Many people may not know about wcdma in Wireless Access networks. It does not matter. After reading this article, you must have gained a lot, I hope this article will teach you more things. In the past 10 years, mobile communication technology has developed by leaps and bounds, and has gone through the first generation of analog mobile communication, the second generation of digital mobile communication technology, and the third generation of mobile communication technology that will be commercially available. The mainstream standard of the third generation mobile communication is divided into three categories: wcdma, CDMA and China's TD-SCDMA, focus on wcdma and CDMA. Based on the considerations of the second generation of mobile communication and the current 3G application in the world, it can be said that wcdma has become the most mainstream and most widely used third generation wireless transmission technology.

However, with the development of multimedia services and data transmission, the quality of communication and the business of communication are constantly increasing. Currently, third-generation mobile communication still cannot support high-speed data services that exceed 20 Mbit/s and a large range of services (8 kbit/s ~ 20 Mbit/s), and the third-generation mobile communication does not achieve real global roaming. Therefore, in recent years, some researchers have proposed a new concept of the future mobile communication system-Beyond 3G.

Beyond3G mobile communication system must be able to support high-speed grouped data transmission of all IP addresses (dozens or even hundreds of Mbit/s of data rates) and support high terminal mobility (Mobile speed up to several hundred kilometers per hour) supports high transmission quality (data service error rate less than 10-6), high spectrum utilization and power efficiency (Emission Power reduced by more than 10 dB ), it can also effectively support changes in the user data rate, user capacity, service quality, and mobile speed. At present, the wcdma standard is constantly evolving towards Beyond3G. Its development direction mainly includes: supporting more multimedia services, improving downstream data transmission rates, and implementing a full IP network, implement switching and roaming between different standards and different wireless access network technologies. In these development directions, it is very important to improve the downlink data transmission rate. The key to solving this problem lies in some new baseband transmission technologies, such as some intelligent signal processing technologies. In addition, the third-generation mobile communication technology has not been commercially available yet, and its technical capabilities have been greatly extended. Therefore, this article starts from this aspect, based on the new technologies used in baseband transmission, we will discuss their application in the third generation Evolution of wcdma.

Wcdma Overview

Wcdma standardization is mainly undertaken by the Regional Standardization Organization 3GPP, which is initiated by ETSI in Europe and is developed by ETSI (Europe), CWTS (China), and ARIB (Japan) the third-generation cooperation organization, composed of three members, such as TTC (Japan), TTA (Korea), and T1 (USA), aims to develop the third-generation mobile communication standard wcdma compatible with GSM/GPRS, it is also called UMTS in Europe. Currently, the wcdma system standards developed by 3GPP include R99, R4, and R5. R99 is currently the most mature and stable version. Its main feature is to introduce a new wcdma and CDMATDD Wireless Access Network RAN Based on the GSM/GPRS core network. The main feature of R4 is to complete the standardization of TD-SCDMA Technology submitted by China in 3GPP. The main feature of R4 core network is to separate the load and control in the circuit domain, this is also the first step towards full IP. R5 is the first version of the full IP address. Its core network structure will change greatly and IP Multimedia domains will be introduced. Another major enhancement of R5 is the introduction of HSDPA that supports 10 Mbit/s downstream speed for wireless interfaces.

From the evolution of the above standard, we can see that the evolution of wcdma includes the evolution of network layer solutions and the evolution of physical layer baseband transmission. Network Layer evolution includes the development of wireless access network resource management technology and core network IP technology. Because the evolution of the physical transmission layer is the foundation, This article focuses on the enhancement of wcdma physical transmission and some new technologies that may be used in the third generation of wcdma evolution.

Key Technologies for evolution of the physical layer from wcdma to the third generation in Wireless Access Networks

The key technologies in the evolution of wcdma to the next three generations include channel coding technology for resisting fading and unexpected errors; multi-user detection technology for overcoming interference between users; multi-Input Multi-Output (MIMO) Multi-antenna technology and AMC technology to overcome Multi-path interference and adopt block transmission technologies; finally, H-ARQ technology is combined with the network layer and physical layer. These technologies can also be combined to jointly improve system performance.