A wireless access point is an access point to a wireless network, commonly known as a "hotspot". There are mainly routing, switching and access integrated devices and pure access point devices. The integrated device performs access and routing work. The pure access device is only responsible for the access of wireless clients. The pure access device is usually used as a wireless network extension. Or the main AP is connected to expand the wireless coverage, and the all-in-one device is generally the core of the wireless network.
1. The principle of wireless access point
Wireless AP is an access point for users to access wired network using wireless devices (mobile devices such as mobile phones and wireless devices such as laptop computers), and is mainly used for broadband homes, inside buildings, campuses, parks, warehouses, factories, etc. that require wireless monitoring In places, the typical distance covers tens of meters to hundreds of meters, and some can also be used for long-distance transmission. The farthest can reach about 30KM. The main technology is IEEE802.11 series. Most wireless APs also have access point client mode (AP client), which can wirelessly connect with other APs to extend the coverage of the network.
2. The role of wireless access points
A general wireless AP has two functions:
2.1 As the central point of the wireless local area network, other computers equipped with wireless network cards can access the wireless local area network through it;
2.2 The purpose of extending the network range is achieved by providing long-distance wireless connections to wired local area networks, or long-distance wired connections to small wireless local area networks.
Wireless APs can also be used to connect small wireless LANs for expansion purposes. When there are enough wireless network users, a wireless AP should be connected to the wired network to connect the wireless network to the wired network backbone. The AP acts as a bridge between the wireless workstation and the wired backbone, enabling seamless integration of wireless and wired. APs allow wireless workstations to access network resources while increasing the available resources for wired networks.
3. The case of wireless access points
Wireless AP
AP, Access Point, wireless access node, session point or access bridge, is a broad term that includes not only a simple wireless access point (wireless AP), but also a wireless router (including wireless gateway, wireless A general term for devices such as network bridges). The wireless AP access point supports wireless applications in the 2.4GHz frequency band, the sensitivity conforms to the 802.11n standard, and adopts dual radio frequency outputs, each with a maximum output of 600 mW. Wireless coverage is deployed in a large area, and it is a necessary wireless AP device for hotels to develop wireless networks.
4. Differences between wireless access points
The difference between wireless AP and wireless router
4.1 Different functions
Wireless AP: The full name of AP is Access Point, and its function is to convert a wired network into a wireless network. To put it figuratively, the wireless AP is the bridge between the wireless network and the wired network. Its signal range is spherical. It is best to put it in a higher place when building, which can increase the coverage. A wireless AP is also a wireless switch. It is connected to a wired switch or router, and the connected wireless terminal is the same as the original network. belong to the same subnet.
Wireless router: A wireless router is a wireless AP with routing function, which is connected to the ADSL broadband line, realizes automatic dial-up access to the network through the router function, and establishes an independent wireless home network through the wireless function.
4.2 Different applications:
Wireless APs are used in many large companies. Large companies need a large number of wireless access nodes to achieve large-area network coverage. At the same time, all access terminals belong to the same network, which is also convenient for company network administrators to easily implement network control and management. Wireless routers are generally used in home and SOHO environment networks. In this case, the coverage area and users are generally not large, and only one wireless AP is enough. A wireless router can realize ADSL network access and convert it into a wireless signal at the same time. Compared with buying a router and a wireless AP, a wireless router is a more affordable and convenient choice.
4.3 Different connection methods:
Wireless AP can not be connected with ADSL MODEM, use a switch or hub or router as an intermediary. The wireless router has a broadband dial-up function, which can be directly connected to the ADSL MODEM for dial-up Internet access to achieve wireless coverage.
5. Application areas of wireless access points
A typical enterprise application involves attaching several wireless access points to a wired network and then providing wireless access to the office LAN. Management of the wireless access point is handled by the wireless LAN controller to automatically adjust RF power, channel, authentication and security. Additionally, controllers can be combined into a wireless mobility group, allowing roaming across controllers. The controller can be part of a mobility domain, enabling customer access throughout a large or regional office location. This saves customers time and administrative overhead as it can automatically re-associate or re-authenticate.
Additionally, multiple controllers and all the hundreds of access points connected to those controllers can be managed through software. The software can handle one of the same functions as the controller but also adds the ability to map the user or RFID locations to upload the map, upgrade the firmware of the controller and access point, and detect/process.
A typical enterprise application is to install several wireless access points on a wired network to provide wireless access to the office LAN. Within the reception range of the wireless access point, the wireless client has both the benefits of mobility and full connectivity to the network. In this case, the wireless access point becomes an interface for the user terminal to access the wired network. Another use is in situations where network cabling is not permitted: for example, manufacturers use wireless networks to connect network connections between offices and warehouses.
6. How to choose a wireless access point
The 802.11b/g-based wireless AP is the most commonly used device for building a small wireless local area network. It acts as a bridge between wireless workstations and wired local area networks in the MAC sub-layer of media access control, and the maximum connection distance can reach 300 feet. With the wireless AP, just like the HUB of the general wired network, the wireless workstation can connect with the existing wired network quickly and easily. Most wireless APs support multi-user (30-70) access, data encryption, multi-rate transmission and other functions. Some excellent products also provide complete wireless network management functions, which can be used in small areas such as homes and offices. , a wireless AP can realize wireless access of all machines. There are basically two types of APs on the market: simple APs and extended APs. In addition to the basic AP functions, the extended AP may also have several Ethernet switch ports, routing, NAT, DHCP, print server and other functions.
With the increasing demand for intelligent mobile terminals and wireless coverage, ubiquitous WIFI wireless applications are changing our lives from offices, residences to public places. There are many hotels and hotels that want to use wireless APs for wireless coverage. Many star-rated hotels not only want to have wireless coverage in the lobby, but also hope that every guest room can also achieve wireless coverage. There are many wireless AP products on the market for wireless coverage, but how to do a good job of wireless coverage economically, welcome to inquire. At the same time, we also put forward our wireless coverage plan, hoping to jointly promote the cause of full wireless network coverage and build a healthy, safe, environmentally friendly, fast, stable, practical and economical hotel wireless network full coverage.
Simple AP: It is more suitable for users who have a relatively sound wired network and only need to extend the wireless function of the network. The main performance indicators for the wireless network part are as follows:
6.1 AP performance: The network location of an AP is roughly the same as that of an access switch, so the maximum number of users that can be accessed at the same time and the data forwarding delay are also important index parameters. APs with better quality can achieve approximately negligible delay and the use of more than 30 concurrent users.
6.2 The size of the power. If the power is too small, the signal coverage and transmission stability of the wireless network will be poor; if the power is too large, it will have adverse effects on the human body. The international standard comprehensively considers that the power of the strongest signal is 100 milliwatts on the basis of being harmless to the human body, that is, 20 DBm. The closer the power of the AP is to this value, the better.
A new type of ceiling-mounted wireless AP has appeared, which uses the circuit to transmit network signals, which greatly increases the coverage area, is practical, beautiful, and is convenient for customers to install.
7. Security Features of Wireless Access Points
Relying on its unique advantages, the Internet has become the fastest growing industry in China and even in the world. According to the latest statistics from DCCI, the number of Internet users in China reached 182 million in 2007. It is estimated that in 2008, the number of Internet users in China will reach 244 million. The decline in computer prices has further accelerated the development of the Internet. It is very common for a family to have multiple computers, and it is the first choice for many families and units to share the Internet with multiple computers at the same time. But due to the traditional wired network, because of its cumbersome wiring, it is also a trouble for many families.
In recent years, with the rapid development of wireless technology, the wireless local area network (Wireless Local Area Network, WLAN) technology has become very mature, and the Internet access speed is getting faster and faster. The mainstream products in 2009 can not only reach the speed of ordinary wired Ethernet, but also have basic security. As a key device for wireless Internet access, the performance of the wireless AP and the placement of its location directly affect the strength of the wireless network transmission signal.
The so-called wireless AP is the wireless access point (wireless local area network transceiver): the wireless hub used in the wireless network is the core of the wireless network. It is the access point for computer users into the wired Ethernet backbone. In order to effectively improve the overall performance of the wireless network, making good use of wireless APs has become an indispensable and important part. How to make better use of the wireless AP and enjoy the real fun of sharing the Internet, you need to grasp the following aspects:
7.1 The installation position should be higher
Since the wireless AP plays the role of a hub in the wireless network, it is actually a "base station" for the transmission of wireless network signals, so its installation location must be selected so as not to affect the stability of the entire wireless network signal transmission. Considering that the wireless communication signal propagates in a straight line, if there are obstacles in the transmission process, the strength of the wireless communication signal will be weakened, especially when encountering metal obstacles, the attenuation range of the wireless signal even more huge. In order to prevent the wireless signal from being interfered by external obstacles, you can install the wireless AP as high as possible, or add a communication relay point on top of the obstacle, of course, you can also use an iron tower To increase the outdoor antenna height of the wireless AP, the mobile or fixed obstacles between the wireless workstation and the wireless AP can be effectively eliminated, so as to ensure that the signal coverage of the wireless AP is large enough, then the overall communication performance of the wireless network will be improved. will be greatly improved.
7.2 Coverage, little overlap
With the help of Ethernet, we can effectively connect multiple wireless APs to build a wireless roaming network, so that users can roam wirelessly in the entire network at will. However, when the visitor moves from one sub-network to another, the distance between the visitor and the original wireless AP will become farther and farther, so that the wireless Internet access signal will become weaker and weaker, and the Internet access speed will also increase. Slower and slower until the signal connection with the original network is interrupted; if there is a small amount of overlap between the wireless AP signal coverage area of ??another subnet and the wireless AP signal coverage area of ??the original network, the visitor is about to connect with the wireless AP signal coverage area of ??the original network. The moment the original network is disconnected, it will automatically enter the coverage area of ??the new subnet, which ensures that visitors are always online when roaming between different networks without finding disconnection. Therefore, when setting up a wireless roaming network, in order to ensure that the wireless network has sufficient bandwidth, it is necessary to carry out a small amount of cross coverage of the respective wireless signal coverage areas generated by each wireless AP to ensure that each wireless subnet can be seamlessly connected.
7.3 Control bandwidth to ensure speed
In theory, the bandwidth of the wireless AP can reach 11Mbps/s or 54Mbps/s, but the bandwidth is shared by other wireless workstations. In other words, if the wireless AP communicates with more wireless workstations at the same time When connecting, the network bandwidth that each wireless workstation can share will gradually decrease. Therefore, in order to ensure that the communication speed of the entire wireless network is not affected, it is necessary to control the number of wireless workstations connected to ensure that each workstation can obtain sufficient Internet bandwidth. So how many wireless workstations can a wireless AP connect to at the same time without reducing the communication speed of the entire network? Generally speaking, a wireless AP that supports the IEEEE802.1lb standard can connect to about 20 workstations at the same time. If the number exceeds this number, the communication speed of the wireless network will drop significantly; of course, if the number of workstations connected to a wireless AP at the same time is small, the networking cost will be too high.
7.4 Communication signals, refusing to pass through walls
If its signal passes through the wall or is interfered with by other things, its communication distance will be greatly shortened; in order to avoid unnecessary weakening of the communication signal, you must control the placement of the wireless AP so that its signal is as low as possible. Passing through walls, let alone pouring reinforced concrete walls. Through the actual test, it is found that within a distance of 10 meters, after the transmission signal of the wireless AP passes through two brick walls, its signal strength can still maintain the highest standard transmission strength, but once the wireless signal passes through the poured reinforced concrete Its signal strength dropped by half when it hit a wall. It is not difficult to see that when the wireless communication signal passes through the metal wall, its signal strength will be greatly attenuated. Therefore, when setting up a wireless LAN in a building with more than two floors, it is best to install a wireless AP on each floor, so as to ensure that all wireless workstations on this floor can be within the coverage of the wireless AP. Inside. In addition, if it is on the first floor, if the number of room gaps is large, then you should ensure that there cannot be more than two walls between the wireless AP and the wireless workstation, otherwise you need to install several more wireless APs to Make sure that each wireless station gets sufficient signal strength. Of course, in order to ensure that all wireless workstations within a building can connect to a network at the same time, you also need to connect wireless APs on each floor or installed in other locations through twisted pair cables.
7.5 Placement, in the center
Since the signal coverage of the wireless AP is a circular area, in order to ensure that each wireless workstation connected to it can effectively receive the communication signal, it is best to place the wireless AP in the center of the connected workstation. For example, the wireless AP can be placed in the computer room or the center of the room, and then each workstation can be placed around the wireless AP, so that each workstation in the computer room can be connected to the wireless network at high speed. In addition, it should be noted that the wireless network usually automatically adjusts the Internet speed according to the distance of the communication distance. Generally, the closer the workstation is to the wireless AP, the stronger the anti-interference ability of its communication signal, then the Internet speed will be higher. The faster it is, on the contrary, if the distance between the workstation and the wireless AP is farther, the communication signal is susceptible to external interference, and the Internet access speed will be slower. Therefore, in order to ensure that the Internet speed is always at a high speed, you must control the distance between the wireless AP and the workstation, and try not to make them too far away. If the distance is really far, you can install omnidirectional antennas for wireless APs, while workstations that are far away need to install directional antennas. At the same time, adjust the direction of the antennas to ensure that they have a suitable small angle with the horizontal line.
7.6 Correct settings, successful roaming
As mentioned earlier, in order to realize wireless roaming, it is necessary to overlap the signal coverage of multiple wireless APs with a small part of each other. However, in order to roam successfully, each wireless AP needs to be properly set. First, you need to log in to the parameter setting interface of the wireless AP, find the SSID setting option in it, and then set the SSID name of all wireless APs to be the same, so as to ensure that roaming users roam in the same network; IP address, so that the IP addresses of all wireless APs belong to the same network segment; next, it is also necessary to modify the channels of wireless APs whose signals cover each other. Considering that there is a signal overlap area between two adjacent wireless APs, in order to ensure that the signal channels used in this part of the area cannot cover each other, specifically, the wireless APs whose signals cover each other must use different channels, otherwise it is easy to cause various problems. Signals between wireless APs interfere with each other, thereby degrading the overall performance of the wireless network. A wireless AP can use a total of 11 channels, of which only three channels 1, 6, and 11 are completely covered, so you can set the adjacent wireless AP to use these channels to ensure successful wireless roaming.
