WiFi is increasingly the preferred mode of global Internet connection. According to the information released by the blog site GigaM, 2.4 billion devices will be connected to the internet. Most of the devices will use wireless way to access the Internet. Although more and more people know WiFi, it is really known to work. Even in the IT expert circle, some facts about the WiFi network are often misunderstood. Here is the top ten common misunderstandings about WiFi.
Shared medium
The radio signal is programmed in each access point (AP) to run on a single channel. In this single channel, multiple clients can be connected and communicated. All clients are shared using its client.
However, the fundamental problem of radio systems is that a wireless station cannot listen while sending, so a collision cannot be detected. In view of this, the developer of 802.11 specification creates a collision avoidance mechanism called distributed control (DCF). According to DCF, a WiFi station is only sent when it thinks that the channel is clear and clear. In this way, the probability of collision will increase with the increase of traffic or in the case where the mobile station cannot "hear". Although there are some protocols of control operations, WiFi is similar to the second floor HUB technology of traditional wired networks.
2.802.11b and traditional agreement "slow" media
The result of making the old agreement in the same environment is to "slow down" all other clients. In fact, traditional customers need to take up more session time to send the same amount of data as 802.11n or 802.11 AC. Call fair algorithms have proven to effectively solve this problem.
3.L1 / L2 802.11 function
It is widely believed that WiFi uses wireless radio frequency (RF) technology, there is no physical wired connection between senders and recipients. When an RF current is supplied to the antenna, the electromagnetic field is created and can then be propagated through space. In fact, the 802.11 protocol is a L2 technology that uses the underlying L1 of the OSI stack to perform his duties. The communication between the client and the access point is connected in the air. Air communication is processed by L2 802.11e standard QoS.
4.DownStream with UPSTREAM
There is a significant difference between DowNStream from the access point to the client and UPSTREAM from the client to the access point. Currently, most WiFi air technology only provides DowNStream enhancements.
5. Upstream rate and downward rate
The universal unique rate in the industry is the transmission rate. However, the asymmetric rate is typical, while the transmission rate seen there in our connectionable client does not necessarily represent the receiving rate. This also confirmed in the access point and infrastructure, which proves that there is a separate upstream rate Tx and downstream rate RX in WiFi world.
6. Same transmission power for all rates
Setting an access point radio to "maximum power" does not mean that the power can be used for all rates. The default wireless transmission power is set to 20 dBm. Typically, the higher the data rate in use, the access point will be forced to reduce the power of these frames (defined by FCC and ETSI). This concept has become more common as 802.11ac VHT specification.
7. Always set the radio to maximum power
It is a good thing to set the radio to the biggest power, but this is likely not a good idea. This has been confirmed that the signal distortion will occur when the radio is sounded with the maximum power. There are many causes, including Cell size planning, etc. Just set the radio power to the greatest practice.
8. Signal intensity and signal noise ratio (SNR)
It is often confusing between the measurement of signal strength and the measurement of signal noise. In fact, the performance section of a WiFi network depends on the signal strength. Between a computer and the wireless access point, the signal strength in each direction determines the available data rate of that connection. Therefore, the stronger the signal, the better the connection. Signal noise ratio is preferably a large number, which means that the receiving strong signal and the background noise difference between the overall quality are different.
9. MIMO and Space Flow
MIMO and space streams may be the most confusing problems since the 802.11n agreement. Multiple Input and Multiple Output (MIMO) technology is a wireless technology that uses multiple transmitters and receivers to simultaneously transmit more data. All wireless products with 802.11n support MIMO, which is part of the technology, allowing 802.11n to achieve higher speed than those who do not support 802.11n. MIMO involves antenna and path, and the number of uses indicates how many antennas and paths can be used to transmit and receive signals. For example, 3 × 3 means 3 antennas and path sends and 3 antennas and path receptions.
The spatial stream involves the actual data. For example, a 3-way spatial flow device can send three unique data streams to the receiving station and are rebuilt into a data set. Finally, add MIMO and space streams equivalent to achievable overall throughput. 3 × 3: 3 means using 3 antennas and path sends and 3 antennas and path reception when sending 3 space flows.
10. Access points and their clients
This is a very simple problem, but it is often overlooked, the smallest centry is always a winner. In order to achieve the highest data rate, the access point and the client must have the ability. It is important to understand the ability of the client to truly understand what WLAN deployment in the real world will be implemented.
Original link: https://www.eeboard.com/news/wifi-11/
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