Wireless bridge brief introduction and practical application

With the development of technology, the technology of wireless broadband network is more and more mature, and it is applied more and more in various fields. At present, the establishment of large-scale monitoring system within the enterprise has become a large-scale factory and mine enterprise in China, parks, scenic spots, roads, etc. The important goal of informatization construction is wireless monitoring system based on WLAN technology. It not only has lower investment cost than traditional monitoring system, but also has unparalleled technical advantages. For example, flexible networking, mobile monitoring, high scalability, etc. It makes it the first choice for enterprises to establish internal monitoring system. When monitoring wireless camera, you can choose analog camera or IP camera. If you choose analog camera, you need to install network video server.

What is a bridge

The bridge is like a smart repeater. The repeater receives signals from a network cable, amplifies them, and feeds them to the next cable. In comparison, the bridge is more sensitive to the information uploaded from the level. A bridge is a technique for forwarding frames. According to the MAC partition block, collisions can be isolated. The bridge connects multiple network segments of the network at the data link layer.

A bridge, also called a bridge, is a storage/forwarding device that connects two LANs. It can split a large LAN into multiple network segments, or interconnect two or more LANs into one logical LAN. All users have access to the server. The bridge connects two similar networks and manages the flow of network data. It works at the data link layer, which not only extends the distance or range of the network, but also improves the performance, reliability, and security of the network. After the network 1 and the network 2 are connected through the bridge, the bridge receives the data packet sent by the network 1, and checks the address in the data packet. If the address belongs to the network 1, it gives up, and if it is the address of the network 2, it Continue to send to the network 2. This can use the bridge isolation information to divide the same network number into multiple network segments (belonging to the same network number), isolate the security network segment, and prevent users in other network segments from illegally accessing. Due to the segmentation of the network, the network segments are relatively independent (belonging to the same network number), and the failure of one network segment does not affect the operation of another network segment.

What is a wireless bridge?

As the name suggests, wireless bridges are the bridges of wireless networks. They use wireless transmission to bridge the communication between two or more networks. Wireless bridges are divided into circuit-type bridges and data-type bridges from the communication mechanism. The circuit-type bridge wireless transmission mechanism adopts the PDH/SDH microwave transmission principle, and the interface protocol is implemented by the bridge principle. It has the characteristics of stable data rate and small transmission delay, and is suitable for the fusion network solution of multimedia requirements, and is suitable for use as 3G/4G. Interconnection of mobile communication base stations.

The data type bridge adopts the IP transmission mechanism, and the interface protocol is implemented by the bridge principle. It has the characteristics of flexible networking and low cost, and is suitable for network data transmission and low-level monitoring type image transmission. It is widely used in various data based on pure IP architecture. Network solution.

Wireless bridge and microwave transmission difference

1. From the frequency above, the wireless bridge is only applied to two frequency bands. One is 2.4G and the other is 5.8G. The microwave product frequency band we mentioned is more, and the microwave refers to the frequency within the range of 300MHz-300GHz. Radio waves. In fact, this wireless bridge is also in the microwave range, just give it a good name.

2, the transmission distance is different, the transmission distance of the wireless bridge is very short, generally 3-5 kilometers away, and the distance of microwave product transmission is relatively long, this needs to be determined according to the actual situation, Generally, when designing a hop link, it needs to be surveyed or tested in advance. For example, there are 30 kilometers, 50 kilometers, and a short 1 kilometer. This is based on the size of the antenna and the frequency band you choose. .

3. The diffractive function is different. The microwave has basically no diffractive function. The higher the frequency, the weaker the diffractive function. Therefore, in our microwave engineering case, a microwave repeater is needed at a very long distance. It is the microwave relay. Here, when it comes to the diffraction function, the 2.4G wireless bridge has a certain diffraction function. For example, if you put a wireless bridge in one room, you can receive the signal in another room. The signal is only Attenuated a bit. The microwave we mentioned needs a direct view, that is, a short distance can be seen by our naked eyes, or can be seen by a long distance through certain instruments, such as can be seen through a telescope.

4, the setting method is different, this is basically the same, the current equipment is basically fool-like, most manufacturers have done the simplest settings in the factory, as long as other conditions are available, set on One or two parameters can be passed, this is not difficult.

5, the use is different, the use is basically the same, can transmit video, audio and data signals, but the 2.4G wireless bridge can be used alone, as a wireless AP to achieve wireless signal transmission. Microwaves do not have this feature.

application

How the wireless bridge will be erected in practice, and then several recommended erection schemes are recommended:

Point to point mode

Point-to-point (PTP), or "direct transmission." Wireless bridge devices can be used to connect two fixed networks in different buildings. They generally consist of a pair of bridges and a pair of antennas. The two antennas must be placed in opposite orientations, and the outdoor antenna is connected to the bridge in the room by a cable, and the bridge is physically connected to the network.

Relay mode

That is, "indirect transmission." It is not visible between two points in BC, but it can be indirectly visible through an A building. And AC two points, BA meets the requirements of bridge equipment communication between two points. The relay mode can be adopted, and the A building is used as a relay point. Each bridge is placed in the BC, and the antenna is directional. The A point options are as follows: I place a bridge and an omnidirectional antenna. This method is suitable for the case where the transmission bandwidth is not high and the distance is relatively close; II, if the point A is a single-point to multi-point wireless The bridge can insert two wireless network cards on the wireless bridge of the central point A. The two wireless network cards respectively connect two antennas through the feeder, and the two antennas respectively point to the B network and the C network; III places two bridges and two sides are oriented. antenna.

Point-to-multipoint transmission

Since wireless bridges often have special requirements when building networks, it is difficult to find power supply nearby. Therefore, it is very important to have PoE (Power over Ethernet) capability, such as Ethernet power supply that can support 802.3af international standard, and can provide 12V DC power to the bridge through the Category 5 line. General bridges can be managed via the web or managed via SNMP. It also has advanced link integrity detection capability. When it is used as an AP, it can automatically detect whether the uplink Ethernet connection is working properly. Once the uplink connection is found to be disconnected, it will automatically disconnect the wireless connection. Workstations, such disconnected workstations can be discovered in time, and search for other available APs, significantly improving the reliability of the network connection, and also facilitate the timely locking and troubleshooting. In short, with the maturity and popularity of wireless networks, the application of wireless bridges will also be greatly popular.

Application Environment

Temporary networking of a pair of speed nets and field operations without high barriers (mountains or buildings). Its range of action depends on the environment and the antenna, now 7km point-to-point microwave interconnection. A pair of 27dbi directional antennas can achieve a 10km point-to-point microwave interconnection. The 12dbi directional antenna can realize 2km point-to-point microwave interconnection; a pair of wireless bridges that only implement the link layer function is a transparent bridge, and has a network layer function such as routing, and the directional antenna in the network 24dbi can realize the heterogeneous layer in real layer. Network-connected devices are called wireless routers and can also be used as Layer 3 bridges.

Wireless bridges are usually used outdoors, mainly for connecting two networks. It is not possible to use only one wireless router. Two or more points are required for peer-to-peer, and the AP can be used alone. The wireless bridge has large power, long transmission distance (up to about 50km), strong anti-interference ability, etc. It does not have its own antenna. It is usually equipped with a parabolic antenna to achieve long-distance point-to-point connection.

Nowadays, 802.11n wireless bridges have appeared on the market, and the transmission rate can reach more than 300Mbps. However, due to various factors, the actual rate is far lower than the value advertised by the merchant. But the rate is actually much higher than the 11g, which also makes us demand high bandwidth and high transmission rate. With the continuous development of technology, it is believed that more new products will be derived with the emergence of new technologies.