Build a remote building Wireless LAN Solution

The connection distance can also be used to connect two LAN segments to realize the communication protocol between the two LAN segments. In the increasingly widely used wireless network technology, wireless bridges are a product required for long-distance network connections.

At present, lan interconnection between buildings has become an urgent issue for many organizations. A company may wish to connect adjacent production and transportation subnets and management centers; in the big school district, the independent internal LAN and Computing Center in the teaching building and Student Dormitory can connect students and teachers to the campus network and the Internet. In short, we all hope that the network can achieve LAN connection between two or more adjacent buildings, provide high-speed Interconnection Network Access, and implement mobile access to network services. According to the traditional idea, to achieve the interconnection of the two buildings, even if it is close at hand, it is also necessary to draw lines and use cables or lease lines.

If conditions in the surrounding environment are met, the cable laying project may not be implemented; renting a DDN line may face many difficulties, such as high rental costs and low line bandwidth. However, now wireless technology has the answer to the above questions.

Long-distance wireless LAN construction mainly has the following structures: point-to-point, point-to-point, bridge-based, and hybrid. Various structures have different application scenarios, so you need to carefully choose based on the actual situation.

Point-to-Point

　

Point-to-Point wireless Bridging Mode

This type is usually used between fixed locations connected to the network, and is a common method of wireless connection. The network built using this connection method has the advantages of long transmission distance and high transmission rate, it is less affected by the external environment. This type of structure is generally composed of a pair of bridges and a pair of antennas.

Point-to-Point

Point-to-Point wireless Bridging Mode

This type is usually used when there is a central point and Multiple Remote points. Its biggest advantage is its low network construction cost and simple maintenance. Secondly, due to the use of omnidirectional antennas in the center, equipment debugging is relatively easy. The disadvantage of this network is that the omnidirectional antenna is used, and the omnidirectional spread of the beam greatly degrades the power and the network transmission rate is low. The network reliability cannot be guaranteed for remote points over a long distance.

In addition, because multiple remote stations share one device, network latency increases, resulting in a lower transmission rate. If the central device is damaged, the entire network stops working. Second, all remote stations and central stations use the same frequency. When a remote station is disturbed, other stations must change the same frequency, if multiple remote sites are affected, changing the frequency is more troublesome and cannot take into account each other.

Bridge trunk

When there are obstacles between the two local networks to be connected, you can use the wireless relay method to bypass the obstacles to complete the wireless bridging between the two points ., The position of the wireless relay point should be the same as that of Network A and Network B. The two oriented antennas connected by the relay wireless bridge aim at the directed antennas of Network A and Network B respectively, the communication between wireless bridge A and wireless bridge B is completed by relay the Wireless Bridge.

There are two ways to build a relay Bridge:

A single bridge adapter acts as a repeater

Two bridges form a relay point back to back

A single bridge can be connected to two antennas through a splitter. This method is very simple and practical for users who are not very sensitive to bandwidth due to the shared bandwidth of two-way communication. Users with high bandwidth requirements can use two backto-back bridges in different frequencies to work in the wireless bridge mode. Each wireless bridge connects an antenna to form a bridge relay to ensure high-speed wireless link communication.

Hybrid

This type of network is suitable for long-distance points, close-distance points, and blocked points of buildings or mountains. When constructing this network, the above several types of network methods are used comprehensively, point-to-point is used for long-distance points. Point-to-point is used for multiple points at close distance, and blocked points are retransmitted.

How to buy a device

Although the bandwidth and transmission distance of the wireless network determine the size of the set-up wireless network, the devices used for the set-up network are the same, the higher the network size, the higher the device price and parameter. The following describes how to purchase a device through the establishment of a point-to-point wireless network that is 200 metres apart.

When implementing an outdoor wireless bridging scheme, we usually need the following devices:

1. Wireless Bridge

Wireless Bridge

Wireless bridging is the core of the entire implementation solution. This is a device for sending and receiving wireless network signals. When selecting a wireless bridge device, you must not only have a certain understanding of the features of the product, but also select a specific installation requirement. For example, point-to-point Wireless Bridge devices can be used to connect two fixed networks located in different buildings. They generally consist of a pair of bridges and a pair of antennas. The two antennas must be placed in a relatively targeted manner. The outdoor antennas are connected to the indoor bridges using cables, while the physical connections between the bridges and networks. A single point-to-point multi-point PTMP wireless bridge device can connect networks of multiple peripheral buildings. However, the structure is more complex and comprehensive antennas are required. Currently, many of the products provided by many merchants support the above two bridging functions.

2. Wireless outdoor targeting Antenna

Wireless outdoor targeting Antenna

Wireless outdoor targeting antenna is also the most important part of the entire implementation solution. Whether the signal can be reliably transmitted over a longer distance depends on the quality of the antenna. The antenna has two key parameters: gain and directionality. Gain indicates the power magnification of the antenna. A larger value indicates a greater magnification of the signal. That is to say, the higher the gain value, the better the transmission quality. The directionality refers to whether the antenna is directed to the radiation and reception, that is, whether the antenna is particularly sensitive to signals from a certain angle and whether the radiation energy is concentrated at a certain angle.

Comparison of various Antennas

According to the horizontal direction of the antenna, it can be divided into an omnidirectional antenna and a targeted antenna with a certain direction in the vertical direction), the maximum gain of the omnidirectional antenna is generally not very large, however, when installing the antenna, you do not need to consider the installation angle of the two ends of the antenna. It is easy to install and suitable for environments with Low distance requirements. However, the gain of the antenna can be very high, generally, the higher the direction, the higher the antenna gain, and the longer the signal transmission distance. However, the more difficult it is to install and adjust an antenna with an excessively sharp direction, the antennas on both sides must be aligned to ensure signal transmission. It is suitable for environments with high distance requirements.

3. Outdoor antenna Lightning Arrester/surge protector

Outdoor antenna Lightning Arrester/surge protector

Outdoor antennas are usually installed on the top of a building and are prone to lightning strikes. If no protective measures are taken, devices are easily burned out during thunderstorms, causing danger. An antenna Lightning Arrester/surge protector is connected in series between a wireless device and an outdoor antenna to prevent damage caused by lightning strikes on devices and personnel. For this type of equipment, you need to pay attention to two parameters: flow capacity and insertion loss. The flow capacity refers to the maximum lightning current that can be dropped by the lightning arrester. The larger the value, the better. The insertion loss refers to the signal attenuation of the lightning arrester. The smaller the value, the better. In addition, lightning arresters must be correctly and effectively grounded, otherwise there will be no lightning protection effect.

4. Outdoor Antenna Feeder

Outdoor Antenna Feeder

Outdoor antenna feeder (Antenna Feeder) is the signal line connecting the indoor Bridge and the outdoor antenna. if the distance between the bridge and the outdoor antenna is too long, the antenna feeder needs to be added. However, this will lead to signal attenuation. In order to reduce this attenuation as much as possible, we need to shorten the distance between the bridge and the antenna as much as possible, and select a antenna with less loss. For example, the NE-5006 feeder loss of XINGNET can be reduced by 1dbi every 5 meters, which is much better than that of ordinary feeder every 3 meters 1 DBI.

5. SMA-N wireless connector conversion line

SMA-N wireless connector Converter

Converting SMA terminal to N terminal is mainly used for connecting Wireless AP & BR to outdoor antenna.

6. feeder conversion head

It is used for the connection between the feeder and the antenna. It is a conversion joint of n terminal male and mother terminal.

Note: usually their connection sequence is: Wireless outdoor oriented antenna --> feeder converter head --> outdoor antenna feeder --> outdoor antenna Lightning Arrester/surge protector --> SMA-N wireless connection converter line --> Wireless Bridge

The above experience is only the experience of the author in purchasing outdoor wireless bridging solutions. Of course, if you need to implement large-scale Wireless Bridge connections, you also need to entrust a company with experience in implementing wireless network engineering to design and construct.

Summary

Although wireless networks are a good solution to remote network connection, before setting up a wireless network, we all need to make scientific planning based on the actual geographical location and the surrounding environment.

Pay special attention to the following:

1. The buildings to be connected must be empty. obstacles such as tall trees and buildings will directly affect the transmission of radio waves.

2. When the bandwidth is reduced, the distance between buildings can be increased for long-distance transmission. At present, the distance between wireless transmission can reach a maximum of 80 kilometers in the case of accessibility, but in the application, the actual distance may be far less than 80 kilometers. Therefore, in the mountainous area, or when there is an obstacle, the distance should not be too long. If you really need it, you can set up a relay station in the middle to bypass the obstacle.

3. to maximize bandwidth, you can connect a wireless bridge to a router that supports redundant channels during short-range wireless LAN transmission. In this way, three wireless bridges can be integrated, in addition, the antenna height is basically unaffected.

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