Wireless Router terminology

What is WDS?

The full name of WDS is Wireless Distribution System, which is a Wireless distributed System. In the wireless application field, he used to help communication between wireless base stations and wireless base stations.

In terms of home applications, the function of WDS is to act as a repeater for wireless networks. by enabling the WDS function on a wireless router, it can extend and expand wireless signals, so as to cover a wider range. To put it bluntly, WDS enables Wireless AP or wireless routers to bridge (relay), but does not affect the coverage of wireless devices during the relay process. In this way, we can use two wireless devices to establish a WDS trust and communication relationship between them, thus extending the coverage of the wireless network to more than doubled, greatly facilitating our wireless Internet access.

What is SSID

Service Set Identifier (SSID). Many people think that the SSID can be written as ESSID. In fact, the SSID is a general concept, including ESSID and BSSID, used to distinguish different networks, A maximum of 32 characters can be entered. the wireless network adapter can access different networks with different SSID settings. The SSID is usually broadcast by the AP, you can view the SSID in the current region through the scanning function provided by XP. For security reasons, you do not need to broadcast the SSID. In this case, you must manually set the SSID to enter the corresponding network. In short, the SSID is the name of a LAN. Only computers with the same name and SSID can communicate with each other.

Wireless Network Mode

11b only indicates that = the network speed runs according to the 11b network standard, 11g only indicates that = the network speed runs according to the 11g network standard, and 11n only indicates that = the network speed runs according to the 11n network standard, 11bg mixed indicates that = the network speed is in the hybrid network mode of 11b and g, and 11bgn mixed indicates that = the network speed is in the hybrid network mode of 11b, g, and n. If you do not know the level of your wireless device, we recommend that you use 802.11b/g/n mixed. If you use 11n only, there may be compatibility problems with old devices. The speed is of course the fastest to support n, but it should also be determined by specific devices.

Which of the following is the best choice for bandwidth options: 20, 40, and automatic?
In general, 20Hz bandwidth is not very high, there is no difference with 11g...

40Hz is because the channel resources are insufficient after the 11N wireless bandwidth is increased, and the bandwidth needs to be expanded to increase the network speed... If 20Hz is selected in 11N mode, the wireless speed is only 65 MBPS (for a m wireless network)

I. What is a channel?

Wireless Network signals are transmitted by electromagnetic waves in the air. The frequency is 2.4 ~ 2.4835 GHz, and these frequencies are divided into 11 or 13 channels (802.11b/G network standard, which is used for common routes ). In my TP-LINK wireless router, there are 13 channels to choose from. Generally, the default channel is "6", which can be used normally in a single wireless network environment, but if it is within the coverage of multiple wireless networks, all wireless routers use the default channel "6", which will definitely cause conflicts and affect the performance of the wireless network.

2. Select channels correctly

First of all, you must be clear that although there are 13 wireless network channels in the 802.11b/G network standard, there are non-overlapping channels, that is to say, there are only one, six, 11 (or 13) channels that do not interfere with each other. Isn't it strange? Can different channels still produce interference or overlap? Indeed! For example, Channel 3 will interfere with Channel 1 ~ 6. Channel 9 interference channels 6 ~ 13. Therefore, to ensure stable operation of multiple wireless networks in the same coverage area, we recommend that you use the Channels 1, 6, 11 (or 13. If there are three wireless networks in the office, in order to avoid interference and overlap, they should use the Channels 1, 6, and 11 in sequence.

For wireless routers used at home, we recommend that you set the channel to 1 or 11 to avoid overlapping signals with other routers to the maximum extent. Because most people do not modify this setting and keep the default 6 channels.

Of course, only three non-overlapping channels are provided in the 802.11b/G network standard. The number of non-overlapping channels available is a little small, however, it is sufficient for ordinary homes or SOHO Wireless Networks. If you need more than three wireless networks in your office area, we recommend that you use wireless devices that support the 802.11a standard to provide more non-overlapping channels, here I will only introduce small wireless networks for families. Therefore, all content is discussed based on 802.11b/G network standards.

3. Channel and protocol knowledge expansion if you are not so familiar with or interested in network or electromagnetism, you can see it here. Because the following knowledge is professional ......

In normal cases, the available channels overlap and intersecret at different frequencies. As a result, only three non-overlapping channels can be used in the network-covered service area, as a result, users in this service area can only share the data bandwidth of these three channels. These three channels are also subject to interference from other radio signal sources, because the 802.11b/g WLAN standard uses the most commonly used 2.4 GHz radio band. This frequency band is also used in a variety of applications, such as Bluetooth wireless connections, mobile phones, and even microwave ovens. The interference of these applications in this frequency band may further affect the use of wireless users.

In the 802.11g and 802.11a standards with the same transmission rate of 54Mbps, 802.11a has more advantages in channel availability. This is because 802.11a operates in a more relaxed 5 GHz band and has 12 non-overlapping channels, while 802.11b/g only has 11, there are only three non-overlapping channels (1, 6, 11, or 13 ). Therefore, 802.11g is not as good as 802.11a in coordinating neighboring access points. Because the 12 non-overlapping channels of 802.11a can provide more choices for access points, it can effectively reduce the conflicts between different channels.

However, everything has two sides. Because of the high frequency band, 802.11a's transmission distance is greatly reduced, and its coverage is only about half or less of 802.11b/g, in actual cases, if an 802.11b wireless router can cover up to 80 meters, then 802.11a can only reach about 30 meters. In addition, due to the complexity of the design, the cost of wireless products based on 802.11a is much higher than that of 802.11b. It is not hard to understand the failure of 802.11a, which is not backward compatible with the dominant channel in the market.

Of course, 802.11g beat 802.11a with the high speed and backward compatibility with 802.11b, but it is still facing embarrassment as wireless devices become more popular. 802.11a supports 12 non-overlapping channels, so its total bandwidth is 54Mbps * 12 = 648 Mbps. The 802.11g only supports three non-overlapping channels, and the total bandwidth is only 54Mbps * 3 = 162 Mbps. That is to say, when the number of connected clients is small, you may not be able to tell the speed difference between 802.11a and 802.11g. However, as the number of clients increases, the data traffic increases and the speed of 802.11g slows down, until the bandwidth is exhausted, let alone 802.11b.

Many people think that Intel's new Intel PRO/wireless 2195A/B/G tri-frequency wireless network card used in Intel's 2-generation Intel has added support for the 802.11a standard. It is seen as a kind of backward or stuck in the market, however, through the above analysis, you will find that Intel may also be positive about the channel and bandwidth confusions caused by 802.11b/g, at least from the feedback from overseas users who popularized wireless networks outside China, this is exactly the case.

In addition, although some vendors are currently developing a wireless LAN solution that is compatible with 802.11a (5 GHz) and 802.11 GB (2.4 GHz) in dual-band scenarios, however, a dual-band access point usually requires two independent RF Modules and corresponding independent data processing capabilities, which will cause high costs on independent devices. However, STMicroelectronics's band-Crossing Technology and other solutions use the band-Crossing Technology. The access points work alternately between two frequencies, rather than simultaneously working in two frequencies. Although they can reduce costs, however, the cost is higher than that of common single-frequency access nodes. Therefore, Intel is compatible with the 802.11a standard in the new version of China. It can be seen as a kind of user short-term solution with strong demand before the new wireless standard is introduced.

In addition, why do frequently-used IEEE 802.11b/g work between 2.4 and ~ In the 2.4835GHz band, these frequencies are divided into 11 or 13 channels-Why 11 channels and 13 channels? This is a different standard in different countries and regions. The standard for North America and FCC is 2.412 ~ 2.462 GHz, with a total of 11 channels, of which channels 1, 6, and 11 are non-overlapping transmission channels. The European/ETSI standard uses 2.412 ~ 2.472 GHz, with 13 channels in total. Among them, Channels 1, 6, and 13 are non-overlapping transmission channels. In Japan, they use 2.412 ~ 2.484 GHz and 14 channels. In addition, there are non-mainstream standards such as four channels in France and two channels in Spain. If the wireless network adapter supports this function, we recommend that you select the FCC (North America) or ETSI (Europe) standard when installing the driver to select the regional Channel standard.