Shulou(Shulou.com)06/01 Report--

With the development of information technology, the network has become an indispensable part of people's life. In the past, people used mobile phones for only three points, looking at the time, making phone calls and sending text messages. Today, the mobile phone has become a scaled-down version of the computer, access the QQ, play Wechat, browse the web, and watch the news. In the past, it was said that the first reaction of people surfing the Internet was a computer, but now it has become a mobile phone, and now it has become inevitable for everyone to have a mobile phone. However, all these have a premise, that is, there is a stable network.

A few years ago, some service places, catering places, in order to attract customers, posted "air-conditioning development" signs at the door, but air conditioners are seasonal and effective only in summer, but now smart businesses have been replaced by "WIFI covered". However, the unstable WIFI coverage effect makes customers irritated and counterproductive. Now mobile phone traffic is already using 4G. If the WIFI network speed is slow or the signal is unstable, many people would rather use the 4G of their own mobile traffic rather than connect to the WIFI, so how to choose the wireless coverage solution to get the most stable effect?

Let's insert a digression here. The most common problem in wireless coverage engineering is co-frequency interference. Among the WIFI channels 1-13, there are only three channels that will not interfere with each other at all. Many engineers know that they have to separate channels when using multiple AP. As a result, they divide the channels one by one, as a result, they divide them one by one, and the interference remains the same. Co-channel interference is a difficult point in the AP world, no AP manufacturer can solve this problem, the only way is to reduce the number of AP. So like mobile, Unicom coverage, generally one AP in one of their buildings, mobile uses 1 channel, Unicom uses 6 channels, avoiding co-channel interference between their own devices and AP of other competing companies. In addition, they also need to consider their own labor costs, including the degree of difficulty of equipment installation, the quantity of works, including the frequency of maintenance in the later stage, and so on. These are all things that engineers need to take into account when choosing solutions and equipment.

At present, there are three kinds of coverage schemes on the market: panel type, ceiling type and a kind of heaven-fed type that most engineers have rarely heard of.

Panel style: everyone is very familiar with the installation of a WIFI panel in each room. The biggest advantage of this scheme is that the signal in the room is 100% guaranteed. However, this scheme also has some shortcomings. First, the use of a large number of equipment, co-channel interference is difficult to avoid, there is no denying that the panel AP can also be set to a different channel for each AP to avoid co-channel interference. Take 20 rooms on the first floor as an example. There is already a certain engineering quantity for 20 panel AP to separate the three channels. Most hotels have more than two floors, but dividing the AP channel is troublesome enough. The real coverage is calculated by space, not by area. The real coverage area of each panel AP is uncertain, the size of each room is uncertain, and the material is uncertain. In addition to considering the interference of the same layer, but also considering the interference of the upper and lower layers, it can only be said that the project is a bit large. Second, each panel has active parts, which supply power independently. The biggest drawback of electronic products is that you cannot guess when it will be bad. Suppose, the damage rate of panel AP is only 1%, but if a hotel or a hotel is covered, the number of panel AP used will be as few as dozens or hundreds. If 1% equals several bad ones, a few in a year is good, in case it goes bad in a month? It's also good to be bad at the same time, what if the separation time is bad? After a project comes down, the later maintenance will have to go back to the local area for maintenance several times a year, which is also what should be taken into account in the project. Third, installation and maintenance trouble, since installed in the room, it is necessary to run from room to room, but in the problem of gradual decline of the signal, it is impossible to test the signal during installation, only installation and test effect, each room is in and out at least twice. And so on, all these should be taken into account by engineers when choosing a plan.

Ceiling: this is no stranger to everyone. AP installed in the corridor, each AP can cover about 4-6 rooms, greatly reducing the use of equipment. Installation is also simple, the equipment is installed in the corridor, do not need to run in each room, generally a floor with 4 or 5 suction top AP can be covered, but also can well avoid co-frequency interference. But each AP is powered independently, and any item has its service life, but the service life of active parts is relatively short compared with passive parts, and there are two uncontrollable problems such as current and voltage that affect active parts. And the suction top AP is connected with the switch with a network cable, so there are two problems, the signal will attenuate with the aging signal of the network cable and AP. Second, the power of the ceiling AP is about the same as that of the home wireless router, which means that covering 4-6 rooms is the limit. If the signal attenuates a little, the signal in the room can not be guaranteed.

Antenna-fed type: this kind of scheme has relatively little contact, what is the antenna-fed type, that is, the AP is connected with the ceiling antenna with a feeder, and the AP is installed in the corridor or weak power well, and then the ceiling antenna is installed in the corridor, and the feeder is connected with the AP to achieve the coverage effect. The ceiling antenna is a passive component, that is to say, it is not easy to be damaged without additional power connection. It is better for a ceiling antenna to use the protective layer of the ceiling antenna. If installed indoors, it is normal for a ceiling antenna to use 5 or 6. The feeder is copper core wire, which is not easy to aging, so as to avoid the problem of signal attenuation caused by line aging. The antenna-feed coverage scheme is generally used by large enterprises such as telecom, China Mobile and China Unicom, because the antenna-feed coverage requires relatively high AP, generally using industrial-grade high-power AP or industrial-grade AP dedicated to the antenna-feed coverage scheme, so as to minimize the number of AP use and completely eliminate the impact of co-channel interference. Generally, the power of the AP used for sky-feed coverage is relatively large, which is 5 or 6 times that of the ordinary ceiling AP, so it can take up several ceiling antennas and ensure the signal in the room. The advantages of day-feed coverage: first, easy to install and use, the equipment is installed in the corridor, the signal covers the rooms on both sides, installation and maintenance do not have to run room by room, the use is as simple as the general home router, after the engineer debugs, the customer can go back to connect the Internet line to use, because the signal output is a feeder, only WAN is the network cable, the customer will not make a mistake. Second, the use of equipment is small, generally only one set of AP is used on one floor, while for the third and fourth floors of a general hotel, use 1pm, 6pm, 11pm, respectively. There is almost no co-channel interference. Third, the signal is strong, generally used for antenna-fed coverage of the AP transmission power is above 1000mW, a floor covered by an AP, it only needs to be connected to 2-4 ceiling antennas, that is, each ceiling antenna can be allocated more than 200mW, that is, more than twice the ceiling AP. However, this scheme also has a fatal disadvantage, because fewer devices are used, and only one or two wireless is used on a floor. If there is something wrong with the equipment, it means that there is no network on one floor, but the probability is relative to the co-channel interference in other schemes. the probability of equipment aging and so on is low.

There are probably only a few wireless coverage schemes on the market, which is not to say which is the best or which is the worst. Because the good quality of the network is not only related to the scheme, but also related to the quality of the equipment. What kind of equipment is used for coverage and what kind of coverage scheme is, in the final analysis, price-oriented, and ultimately depends on the budget given by the customer. If you want to say which scheme is more appropriate, from the perspective of engineers, it is more appropriate to provide coverage, because after all, large network companies are using this scheme.

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