How to Understand WiMAX-based hybrid networking (1)

With the development of multimedia communication, people need a higher rate, higher coverage rate, and a mobile wireless broadband access method. The emergence of WiMAX technology meets people's needs for wireless Internet.

If Wireless LAN technology solves the "Last one hundred meters" access problem, WiMAX technology is the best solution for "last mile" access.

1. WiMAX technology

Global Microwave Access interoperability (WiMAX) is a wireless MAN technology that features higher data transmission rates, more flexible deployment, higher configuration scalability, and wider coverage. The advantage of WiMAX network determines that it will be an important part of the future wireless communication network.

In the future, WiMAX and other wireless network technologies will likely coexist in the market, just as the GSM and CDMA systems of mobile communication today coexist. WiMAX can adopt the same networking mode as Wi-Fi/3G in the networking structure, and can adopt a hierarchical, flat, Mesh network structure and a flexible networking mode combining the three. In the future wireless communication field, various wireless access technologies will coexist, and various mobile communication systems will be mutually compatible and cooperative.

2. hybrid networking of TD-SCDMA and WiMAX

The third generation mobile communication technology mainly includes WCDMA, CDMA 2000, TD-SCDMA and so on, with voice communication, although it can maintain communication at high speed mobile, but the highest data transmission rate is only 2 Mbit/s, it cannot meet the requirements of mobile cities. WiMAX is suitable for providing high data rates in some hotspot areas, while 3G can achieve wide area coverage. Therefore, 3G and WiMAX are destined to be complementary technologies, and their integration is of great significance.

The WiMAX mobile communication system is mainly used for group data transmission. Its peak data transmission rate can reach 75 Mbit/s, which is much higher than 3G systems, however, its main applications are fixed, portable, or low-speed mobile user access. In the initial and middle stages of network construction, it does not support high-speed mobile Seamless Roaming. The 3G mobile communication system has the advantages of supporting fast roaming and providing the call service functions covering the entire network. If the WiMAX and 3G systems are combined during networking, WiMAX will focus on broadband wireless to meet the needs of high-speed data services in hotspot areas, 3G focuses on achieving the high quality and Seamless Roaming requirements of voice communication for mobile communication, which can complement each other and complement each other. This can save the investment costs of the two, achieve a win-win situation, and meet the needs of users for one-card multi-use. Although there are major technical differences between the two, some of the interfaces in the air, TD and WiMAX, both use the TDD method, which makes it possible for TD to learn from the WiMAX air interface technology, TD can maintain its own advantages while learning from WiMAX air interface technology to develop TDD-OFDM technology, so that it can better to B3G or even the future of 4G evolution. Therefore, the 3G and WiMAX joint networking is feasible, and is a very advantageous hybrid networking system.

TDD (TD-SCDMA) Independent networking weaknesses:

(1) The same frequency of the sending and receiving channels cannot be used for interference isolation with frequency selectivity.

(2) In order to implement electromagnetic compatibility between different networks and FDD, the reserve of large protection bands affects the overall spectrum utilization efficiency.

(3) There is no experience in large-scale TDD networking worldwide.

(4) The global roaming service still faces great challenges.

That is to say, from the aspect of channel computing and base station construction, the construction of high-quality and high-speed data seamless coverage requires that the cell radius cannot be too large, otherwise the investment scale is too large, in addition, it is not suitable for supporting data service coverage in hotspot areas economically. However, WiMAX can solve these problems. The ideal joint networking solution is to use WiMAX to support high-speed data services and use WiMAX to cover high-speed data-intensive urban areas, with the help of TD-SCDMA to support fast roaming and the advantage of the call service that can provide full network coverage, the continuous coverage of voice and low speed data is realized, in addition, you can use the WiMAX system to provide the E1 interface to interconnect the TD base station, as shown in figure 1. In this way, the advantages of the two systems can be complementary. Specifically, for 3G users, the combination of WiMAX and 3G can provide higher-speed broadband data services and cheaper broadband access prices. For WiMAX users, the combination of WiMAX and 3G can provide wider wireless access services and better mobile performance. In addition, the combination of WiMAX and 3G helps reduce the construction and operation costs of 3G networks and improve the service quality of mobile and wireless broadband services.

Figure 1 hybrid networking of TD-SCDMA and WiMAX