The World Interoperability for Microwave Access forum is a non-profit production group established by equipment and device suppliers that use the IEEE 802.16 standard, the new IEEE wireless communication standard 802.16.WiMax has become synonymous with the 802.16 standard. It is a broadband wireless access technology for man and can provide high-speed wireless connection for the Internet. WiMax's wireless signal transmission distance is up to 50 kilometers, and its network coverage is 10 times that of 3G (3rd Generation, third-Generation mobile communication) base stations. World Interoperability for Microwave Access (Global Microwave Access Interoperability) is a Broadband Wireless Access Metropolitan Area Network (BWAMAN) Technology Based on the IEEE 802.16 standard, its basic goal is to provide a broadband wireless access method that can effectively interoperate with each other in a single-to-multiple-point multi-vendor environment of the man. Many of WiMax's supporters set up the WiMax Forum as early as, and relevant research was carried out earlier. The WiMax Forum aims to promote IEEE 802.16 wireless broadband network technology. The Organization currently has 105 members, including Alcatel, AT&T, BT, FUJITSU, nokia, Intel, and other industry giants.
1. Technical advantages of WiMax
The technical advantages of WiMax can be summarized as follows:
◆ The transmission distance is far.
WiMax's wireless signal transmission distance is up to 50 kilometers, which is incomparable to WIFI (Wireless LAN). Its network coverage is 10 times that of 3G base stations, only a few base stations can be built to achieve full coverage, which greatly expands the scope of wireless network applications.
◆ High access speed.
WiMax provides a maximum access speed of 70 M, which is 30 times the bandwidth provided by 3G. This is indeed an amazing improvement for wireless networks. WiMax uses the Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing) modulation method. The bandwidth of each channel is 20 MHz, and radio waves are sent and received stably through an outdoor fixed antenna, it can achieve the maximum transmission speed of 74.81M.
◆ Provides a wide range of multimedia communication services.
As WiMax is more scalable and secure than Wi-Fi, it can implement telecommunication-grade multimedia communication services. This includes voice, data, and video transmission.
2. Technical Features of WiMax
◆ Link Layer Technology
One of the characteristics of TCP/IP protocol is that it has high requirements on channel transmission quality. In the face of increasing IP data services, wireless broadband access technology must meet the requirements of TCP/IP protocol for channel transmission quality. Due to the application of WiMax technology (outdoor distance), the fading phenomenon of wireless channels is very significant, and the efficiency of using TCP/IP protocol on wireless channels with unstable quality will be very low. The WiMax technology adds the ARQ mechanism to the link layer to reduce information errors arriving at the network layer, which can greatly improve the service throughput of the system. At the same time, WiMax uses antenna arrays, antenna polarization methods, and other Antenna Diversity techniques to cope with the fading of wireless channels. All these measures improve the performance of WiMax wireless data transmission.
◆ QoS performance
WiMax can provide users with data, video, and voice (VoIP) services with QoS performance. WiMax can provide three levels of services: CBR (Con-stant Bit Rate, fixed bandwidth), CIR (Com-mitted Rate, promised bandwidth, BE (Best Effort, Best Effort ). CBR has the highest priority. In any case, network operators and service providers provide services to users with high priority, high speed, and low latency to ensure the bandwidth they have subscribed. The priority of CIR is second, and network operators provide it at the specified rate. However, when the rate exceeds the specified peak, the priority is reduced, you can also provide more transmission bandwidth based on the bandwidth resources of your device. BE has a lower priority, which is similar to the best-effort service of a traditional IP network. The network does not provide priority and speed assurance. When the system meets the needs of other users' high-priority businesses, it tries its best to provide users with transmission bandwidth.
◆ Working frequency band
In general, the 802.16 operating frequency band uses a no-Authorization frequency band ranging from 2 GHz to GHz, while the 802.16a is a broadband wireless access system that uses 2g to 11 GHz without authorization frequency band, the channel bandwidth can be adjusted from Mbps to 20 MHz as needed. Therefore, the 802.16 spectrum is richer than any other wireless technology and has the following advantages:
(1) For known interference, narrow channel bandwidth helps avoid interference.
(2) when there is little demand for information bandwidth, narrow channel bandwidth helps to save spectrum resources.
(3) flexible bandwidth adjustment capability helps operators or users coordinate spectrum resources.