China Mobile's WLAN centralized mining in 2012, the final scale of this centralized mining is about 1.5 million APs, and was finally shortlisted by 10 companies. From the pattern point of view, the traditional strong WLAN enterprise H3C is not shortlisted; the equipment manufacturers (Huawei, ZTE, etc.) that were strongly involved in the carrier-grade WLAN market last year also did not appear on the list.
However, China Mobile did not directly delineate the final share of each supplier. According to the requirements of China Mobile, all products of the finalists still need to undergo a second round of supplementary testing. The results will be divided only after the results of the supplementary testing.
In the eyes of many people, China Mobile puts the price factor too high in WLAN centralized procurement, which is basically price-only. The size of the shortlisted companies may not be large, and thus question the final quality of the network; more views It is believed that after China Mobile begins to implement a large-scale TD-LTE network, WLAN will lose value as an important access method for mobile broadband networks.
But is this really the case? According to the specific operation cases of Shandong Mobile, WLAN not only directly carries a large amount of data traffic, but also achieves a good internal rate of return on investment; at the same time, it also has a good meaning for TD-SCDMA and TD-LTE. On the "seamless connection".
Confrontation
With the widespread deployment of mobile broadband networks and the rapid growth of smart terminals, mobile data has ushered in rapid development, which has also brought happiness to operators. That is, the mismatch between traffic and revenue growth, the difficulty of cellular network congestion is difficult solve.
As a local area network technology, WLAN can distribute mobile data traffic at low cost, so the headquarters of the three major operator groups have all given high enthusiasm to WLAN. But in the process of construction and operation, there has been controversy. One thinks that WLAN is a local area network technology, and its existence is only temporary, and the operator is not suitable for large-scale construction and operation; the other thinks that WLAN can provide users with low cost and high bandwidth The wireless access method should be constructed and operated. Therefore, some provincial operators are uncertain about WLAN and want to invest in construction and worry that the recovery after investment will not meet expectations.
The actual operation case of Shandong Mobile gives a clear answer.
Shandong Mobile started to officially promote WLAN in 2010. Last year, the number of registered users reached about 5.9 million. In 2012, the user growth rate was as high as 35%, and user development was very rapid. At the same time, the user structure has been further optimized. With the popularity of smart phones in 2012, the proportion of WLAN mobile phone users rose to 42.8%. With the rapid popularity of smart phones, it is expected that the proportion of mobile phones using WLAN will continue to increase.
In terms of traffic, Shandong Mobile ’s WLAN traffic reached 281.5 billion MB in 2012, with a growth rate of 420%, accounting for nearly 85% of all traffic in that year, greatly reducing the pressure on other networks. But will this cause light load or no load of TD-SCDMA network? Through careful analysis of the data, we can find that although the traffic of WLAN users is growing rapidly, it mainly meets the needs of users for mobile Internet access. The main performance is that the traffic volume of other networks continues to grow, and the WLAN network bears most of the new traffic.
In terms of direct value, Shandong Mobile ’s WLAN operating income in 2012 reached 500 million yuan, and the revenue growth rate was as high as 350%. It is expected that the internal rate of return of WLAN investment in the next few years will be around 15%, which is higher than the national internal rate of return reference value 12 %.
prospect
Mobile broadband has always been a love-hate business of China Mobile.
First, the TD-SCDMA network is relatively thin. Although more than 300,000 base stations have been built, the overall capacity of China Mobile ’s mobile broadband network and coverage in hotspot areas need to be improved. At the same time, the time for TD-SCDMA smart terminals to fully mature Not long, it also limits its development.
But with the continuous maturity of TD-SCDMA terminals and the potential construction of TD-LTE networks, is there any use for WLAN? The answer is yes. Because the construction cost of cellular networks is relatively high, operators all hope to recover the cost through the realization of traffic, while the construction cost of WLAN is relatively low. Although TD-LTE will be put into operation, the construction cost of the network carrying the same data is higher than that of WLAN, which determines that its pricing cannot be lower than WLAN. Therefore, from the perspective of network cost, WLAN is currently a suitable choice.
Practical experience in the construction and operation of cellular mobile communication networks shows that it usually takes about 5 years for the network to mature from planning and construction to operation. This can be confirmed from China Mobile ’s TD-SCDMA, which began commercial trials in 2008 until this year It only matured at the beginning of the year. Therefore, it will also take several years for the 4G network to be built from now until its operation is mature.
WLAN, as a local area network technology that carries data services in hotspot areas, can be quickly deployed and immediately put into use, and can use low-cost operations to meet users' high-bandwidth wireless access needs. From the perspective of network upgrades and development cycles, building a WLAN network is also a suitable choice.
From the perspective of the traffic distribution of cellular mobile communication networks, mobile data traffic is mostly concentrated in specific base stations or cells. Some data show that usually 15% of the base stations transmit about 50% of the traffic, and very concentrated cells account for no more than 10% of all their cells. And WLAN just meets the mobile data traffic access requirements within a certain range, and can distribute traffic in these hotspot areas. Therefore, the application characteristics of WLAN and the hotspot characteristics of data traffic are very consistent, and it is also very suitable to choose WLAN network to distribute mobile data traffic.
1. What wireless network
Wireless network, as the name suggests, is a way to build a network without relying on network cables, which is mainly achieved by using wireless communication technology. There are two main ways of wireless network (such as 4G, 3G or GPRS) and wireless local area network (WiFi) through mobile communication networks.
2, What wireless bridge
Wireless bridge, as the name suggests, is the bridge of wireless network, which uses wireless transmission to achieve a communication bridge between two or more networks. In addition to having the basic characteristics of a wired bridge, a wireless bridge works in the 2.4G or 5.8G wireless license-free frequency band, making it easier to deploy than other wired network equipment.
From the function to understand the wireless bridge, it can be used to connect two or more independent network segments, these independent network segments are usually located in different buildings, hundreds of meters to tens of kilometers apart, can be widely used in the interconnection between different buildings.
At the same time, according to different protocols, wireless Bridges can be divided into 802.11b, 802.11g and 802.11n in the 2.4GHz band and 802.11a and 802.11n wireless Bridges in the 5.8GHz band.
3, the meaning of wireless bridge 2.4G and 5.8G
2.4G Bridge:
The advantages are low frequency, large wavelength and strong diffraction ability. Simply put, the propagation performance is good, and the propagation path is slightly shielded. Then there is the relatively low cost.
The disadvantage is that there are many devices using the 2.4G band, and the electromagnetic wave signal emitted by the bridge is easily interfered with the signal emitted by other devices, resulting in a decrease in transmission quality. Moreover, it is limited by the transmission bandwidth of the 2.4GHz band itself, which generally does not exceed 300Mbps
5.8G Bridge:
The advantages are high frequency, relatively pure channel, and large transmission bandwidth. The transmission bandwidth starts at 433Mbps and can easily reach more than 1Gbps. It is suitable for scenarios that require high data transmission.
The disadvantage is that the frequency is high, the signal wavelength is short, the penetration is poor, and there can be no shelter during the propagation. The cost of 5.8G equipment is higher than 2.4G, and it is still in the popularization stage.
Wireless bridge transmission system is usually composed of two or more wireless devices, due to the two-way transmission of data, each device needs to have the ability to send and receive wireless signals.
4, the working principle of wireless bridge
The working principle of the wireless bridge is that the bridge uses the air as a medium to transmit signals, which is simply that one end of the bridge converts the signal in the network cable into a wireless electromagnetic wave signal and transmits it to the air in a directional manner. The bridge at the other end does the opposite, picking up radio electromagnetic signals in the air and converting them into wired signals.
The wireless electromagnetic wave signal can be transmitted by air as the transmission medium, which can solve many problems of difficult construction of wired deployment: such as highways, rivers, mountain streams, or road hardening, and wired deployment and construction difficulties.
Wireless bridge networking has obvious advantages, and can achieve point-to-point or point-to-multipoint network connections at distances of up to 50 kilometers, and data transmission speeds of up to 108Mbps. Effectively solve the problem of network connectivity in the interval, as long as the wireless signal coverage area, the client can easily access the network, the fusion system, without any wiring, the wireless terminal can achieve zero configuration access, so it is very easy to carry out network maintenance and expansion.
Bridges are generally used in the following scenarios: wireless data acquisition, monitoring data transmission (outdoor and elevator), outdoor wireless coverage, outdoor remote wireless bridging, private ISP wireless broadband, unmanned monitoring station data return, etc.
5. How to choose the right bridge
Wireless bridge is a wireless monitoring and transmission equipment commonly used in the field of wireless monitoring, although it is a wireless device like wireless AP and Wireless Router, but it does not need to build wifi coverage, but is used to wireless transmission of video data. Like the switch in wired monitoring, the wireless bridge is an important transmission equipment in wireless monitoring, which is widely used in the two major fields of outdoor surveillance video transmission and elevator surveillance video transmission.
There are many kinds of wireless Bridges on the market, so how to choose a bridge that suits your needs? We will answer your questions from the following aspects.
â‘ Transmission distance
Wireless monitoring projects need to transmit the distance is not the same, wireless bridge transmission distance there are many kinds, some transmission 1~3 km, some transmission 3~5 km, some transmission 5~10 km, some transmission more than 20 km, must be determined according to the monitoring of the transmission distance, as far as possible the maximum transmission distance of the bridge is greater than the monitoring transmission distance, Because rain, fog, snow and other weather in the actual application environment will cause the transmission performance of the bridge to decline, the project construction should reserve sufficient performance margin.
â‘¡ Transmission bandwidth
There are many kinds of transmission rates of wireless bridge, such as 150Mbps, 3000Mbps, 450Mbps, 600Mbps, 900Mbps, etc., which rate to choose can be determined according to wireless monitoring requirements. What users actually need to consider is the transmission performance of the bridge over a specific distance, rather than the theoretical bandwidth data. For example, the theoretical transmission bandwidth of the IP-COM AP625 bridge is 433Mbps, and the actual point-to-point transmission bandwidth can reach 200Mbps at a distance of 2 kilometers, with 25 200W cameras without pressure.
â‘¢ Operating frequency
There are two main operating frequencies of wireless Bridges, 2.4G and 5.8G, and the characteristics of the two Bridges are different. In general, 2.4G wireless bridge is the current mainstream frequency band, good compatibility, good diffraction ability, but the anti-interference is relatively poor, especially in the urban area is vulnerable to wireless signal interference transmitted by other WiFi devices. The 5.8G channel is relatively pure, the anti-interference ability is better, the transmission distance is long, but the diffraction ability is poor.
Urban, downtown, long-distance transmission, camera stream is large, 2.4G interference is more, choose 5.8G wireless bridge. Others such as the transmission distance is relatively close, relatively remote, and the same frequency interference is less, etc. 2.4G wireless bridge is used
â‘£ antenna
Antenna is an important part of wireless bridge, used to transmit and receive wireless signals, no antenna, wireless bridge can not achieve communication. There are many types of antennas, including omnidirectional antennas and directional antennas. Omnidirectional antenna is used for short-range coverage and transmission, and directional antenna should be selected for long-distance bridge. The larger the gain of antenna, the better the performance of wireless bridge.
⑤ Power supply mode
The working environment of the wireless bridge usually involves some complex outdoor environments, such as forests, ports, tunnels, reservoirs and other places, so the power supply is a more troublesome problem. Choosing a wireless bridge that supports POE cable power supply can solve this problem well. IP-COM bridge all support PoE injector power supply, power supply distance up to 60 meters.
â‘¥ Protection level
The wireless bridge works outdoors, the environment is changeable, such as rain, rain and snow, high temperature, etc., the first requirement is waterproof, dustproof, heat resistance, and condensation resistance. For a qualified wireless bridge, these "qualities" are a must.
⑦ Pairing method
At present, there are three mainstream bridge pairing methods: key pairing, dip code pairing, automatic pairing. In terms of the simplicity of engineering applications, especially for projects that install dozens or hundreds of network Bridges at a time, automatic pairing is undoubtedly the best choice. IP-COM network bridge supports the automatic pairing of two network Bridges when they are powered on in the factory state, greatly reducing the workload.
6, wireless bridge installation requirements
Wireless bridge is an important transmission equipment in wireless monitoring, which is widely used in outdoor surveillance video transmission and elevator surveillance video transmission. In addition to selecting the right wireless bridge, we also need the bridge equipment to give full play to its performance advantages after installation to assist users in the project. Therefore, for some installation requirements and precautions of wireless bridge, we should pay more attention to avoid various problems in the later stage.
â‘ Installation height
In the process of wireless transmission, obstacles such as trees, buildings and large reinforced buildings will weaken and block wireless signals. In order to improve the wireless transmission performance and prevent signal damage and weak signal, the user should try to ensure that there are no obstacles in the transmission route of the wireless bridge during installation, and meet the transmission conditions that the two ends can see each other.
Both ends can not be simply understood as point-to-point visibility, which means that there can be no obstacles or potential obstacles in the Fresnel zone (radio wave terminology) in which the antenna is propagated. The main RF energy between the antennas is transmitted in this area, so the transmitting antenna must be high enough above the obstacle to maintain a line of sight path between it and the receiving antenna in order for the communication link to work properly.
â‘¡ Angle and signal debugging
Since the quality of the wireless bridge signal is directly related to the bandwidth and stability of the link, it is necessary to further debug the wireless bridge signal after the installation is completed (the signal strength can be adjusted by adjusting the direction of the antenna on both sides, the pitch Angle, etc.). The signal strength can be checked according to the signal status indicator of the bridge device (three lights, three signals are best, two are average, and one is poor) or the software. Detailed installation procedure for outdoor wireless aps
â‘¢ Requirements for lightning rod
When the wireless bridge is installed in the field, if there are no tall buildings or lightning rod protection nearby, lightning protection measures need to be considered, usually using lightning rod, generally installed in the urban area or surrounded by lightning rod protection, can not be set separately.
It can be seen from the characteristics of the lightning rod that the lightning rod is a lightning source, and the lightning rod will discharge in the grounding path when it is hit by lightning. Therefore, the lightning rod and the protected equipment need to be insulated, otherwise the lightning rod will have a lightning effect on other equipment when discharging. Due to the tip discharge characteristics of the lightning rod, it is easier to cause lightning discharge than the general equipment, so if the lightning rod cannot be isolated from the protected equipment, it will increase the probability of lightning strikes of other equipment. Therefore, the lightning rod grounding must be separate from the device grounding and cannot share the same grounding.
Do enterprises most afraid of products can not be sold, enterprises have no visibility. Now is the Internet era, the era of wine not afraid of the alley is gone. Want to do a good job in sales, please register for free Aike business network members, you can free release product sales information, industry exhibition information, investment information, can also release corporate news, new product delivery and other advertising articles. There are more than a dozen vertical business websites under the Aike business network, such as plastic business network, chemical business network, instrument business network and so on. Register an account and you can publish business information on more than 10 platforms for permanent display. Colleagues are on the move, you must not forget oh.
â‘£ Power supply requirements
The normal input voltage of the PoE power module of the bridge ranges from 100V to 240V and the output voltage ranges from 24V to 48V. If the voltage is lower than or higher than this voltage, the normal operation of the device is affected or the PoE power module is damaged. In view of the unstable and high voltage field power supply, it is necessary to design a PoE power supply solution (such as regulated power supply and UPS power supply) that ADAPTS to the working voltage.
Because the bridge is a precision electronic equipment, it has high requirements for power supply, and is vulnerable to the impact and influence of other power supply equipment, so the power supply of the bridge should be separated from other high-power equipment such as pumping units, oil pumps, etc. When taking power at the same location, UPS, regulated power supply or isolation transformer should be installed to filter out the influence and interference on the power supply when the high-power motor is working.
When the PoE module is used to power the bridge through the network cable, the recommended distance is not more than 60 meters. When this distance is exceeded, it is recommended to move the transmission line near the bridge to meet the recommended power supply distance.
⑤ Device grounding requirements
The wireless bridge should be grounded. If the device is not grounded, the device may run abnormally or be damaged. The grounding resistance of the device should be less than 4 ohms, and the grounding cannot be shared with the lightning rod or strong current line. If PoE power is used, the ground cable also needs to be grounded. Users can ground a Class 5 (or higher) shielded network cable with a ground cable and a PoE adapter to effectively prevent static electricity and lightning strikes. The ground cable and ground point should be waterproof using waterproof tape and waterproof cement according to the waterproof requirements to prevent the ground point from being exposed to the air for a long time, which may cause oxidation or rust.
7, wireless bridge erection method
There are four common wireless bridge transmission modes, the distribution is point-to-point, point-to-multipoint, relay, reflection, here the first monitoring combined with pictures for you to briefly introduce the characteristics of these four wireless transmission modes.
â‘ point-to-point transmission
Point-to-point transmission mode is the simplest transmission mode, that is, we often say PTP, to a single device transmission, and then received by a single device, one-to-one transmission and reception is simple and direct. Point-to-point transmission mode of wireless bridge is often used in the case that the transmission distance is long, or the monitoring point is widely distributed, and point-to-multipoint transmission cannot be achieved.
â‘¡ Point-to-multipoint transmission
The point-to-multipoint transmission mode is developed based on the point-to-point transmission mode, which is often represented as a receiving end to multiple transmitting ends, and is often used for the situation where the transmission distance is relatively close, there are more monitoring points and the distribution is dense.
â‘¢ Relay transmission
The relay transmission mode is because the transmitting end and the receiving end can not avoid the barrier blocking the microwave signal, so the transfer equipment is added in the middle, so that the microwave signal is smoothly transmitted to the receiving end through the transfer equipment, this mode is due to increase the transfer equipment and increase the equipment cost investment, so it is generally not used when unnecessary.
â‘£ Reflection transmission
Reflection transmission is microwave transmission with the help of objects outside the transmission device, such as the transmitting end and the receiving end can not be seen, but there is a large building or a mountain with smooth rock walls in the middle, so that you can adjust the Angle of the equipment, through the building or mountain to reflect microwave signals for wireless communication.
Wireless Bridge,Wifi Wireless Bridge,Gigabit Wifi Bridge,Long Range Wifi Bridge
Shenzhen MovingComm Technology Co., Ltd. , https://www.mcrouters.com