Technical Analysis of wireless city construction and frequent reuse Solutions

The development of wireless cities in China has shown a strong momentum. In addition to large-scale deployment in Taipei and Hong Kong, Beijing, Shanghai, Guangzhou, and Wuhan in Mainland China, shenzhen and other places have or are preparing to start wireless city construction. Currently, the main Wireless Technology System Used in wireless city construction in mainland China is Wimax + Mesh-wifi. Wimax is in a wireless backbone network, which is used to gather traffic in various regions and connect to wired networks; mesh-wifi is in the wireless access layer, which completes the access from the terminal to the network and the small range of wireless data. The benefits of using Mesh-wifi as the wireless access layer are:

1. the Wi-Fi technology industry chain is mature. There are a wide variety of products in various stages, full competition, and low prices.

2. the Wi-Fi technology is developing fast, and technologies for improvement in various aspects are constantly emerging and standardized. The future evolution path is clear.

3. The number of Wi-Fi terminals is huge. Mobile phones, laptops, and other electronic products are built in with Wifi functions. Potential customers are huge and the market prospect is attractive.

4. Mesh wifi technology can effectively solve the problems encountered during wireless network construction in cities, greatly reducing engineering difficulty, saving construction costs, and shortening the construction cycle.

Despite the above benefits, the Mesh wifi network also has some problems. In addition to the interference problems that have been introduced, frequent switching is one of the issues that must be considered because the network uses frequent point multiplexing.

Due to the limitation of frequency points, any large-scale Mesh-wifi wireless network must use frequency point multiplexing technology to build a cellular network to increase the capacity of the entire system. To use wifi technology in a large scale in a wireless city, you must also use cellular networking to reuse limited frequency points in space to achieve broadband coverage throughout the city. One of the most important problems in cellular networks is inter-cell switching. Since the Wi-Fi technology was initially not designed in accordance with the requirements of large-scale telecom operation systems, even if it is relatively simple to switch over the same frequency, there is no rule in its basic version for cross-AP switching. With the gradual development and popularization of WIFI products, small-scale Wi-Fi networks have been established in some regions. during use, it is found that the switching efficiency between terminals in the AP is very low, and real-time services such as video monitoring and voice cannot be carried out. To solve this problem, IEEE has formulated the inter-AP switching specification and specifically described the switching problem in other relevant specifications. At present, the Wi-Fi terminal that implements the switching function is ideal for switching between the same-frequency AP. However, the switching effect between different-frequency APS still cannot meet the real-time service requirements. In contrast, the Specification System in the 2G/3G cellular system provides a very detailed description of switching, mobile phones and other terminals have no impact on real-time voice services, regardless of the same-frequency switching or abnormal-frequency switching.

As the only professional equipment manufacturer of Mesh wifi in China, Shanghai huichuang communication (GBCOM) proposed targeted solutions. Shang Tao, vice president of technology, said: "solving this technical problem of abnormal frequency switching, you can use the Virtual Control CHannel mechanism, which has been implemented in GBCOM Mesh devices." The virtual channel mechanism is similar to the control channel and Data Channel Separation Mechanism in 2G/3G. Through the virtual channel mechanism, GBCOM Mesh terminal devices can be connected to network devices on multiple different channels at the same time. When the network is moving, the GBCOM Mesh device can receive AP signals on multiple channels at the same time, and can be connected to multiple cross-frequency APs at the same time. When switching between two different-frequency APs, it takes only 10 ms for data transmission to switch from one AP to another. When a common Wi-Fi terminal switches from an AP to another AP with a different frequency, it usually requires a network search process, followed by a network connection process. The entire switching process may be up to 10 s. With such a switching efficiency, real-time services are completely unimaginable, and even some non-real-time services will have a negative impact on end users due to the long switching process.

It is understood that in order to adapt to the needs of wireless city network development, to ensure that the existing wifi terminal can achieve smooth switching, in addition to the MESH terminal device to achieve a different frequency switching function, GBCOM is about to launch the terminal optimization software, which includes the unique switching technology of GBCOM, which can ensure seamless switching between different frequency AP and lay a solid foundation for large-scale deployment of wireless cities.

Wi-Fi technology was initially not designed based on the requirements of the telecom operation system. There are still some key technical problems directly applied to wireless cities. These problems will directly affect the success or failure of wireless city operation. In the face of technical challenges, equipment providers and operators must work closely together to solve existing technical problems from the perspective of large-scale telecom operations and expose more potential problems that are not considered, it standardizes and standardizes telecom-level operation networks based on Mesh wifi technology to promote the effective deployment of wireless cities and promote the maturity and prosperity of the wireless city market.

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