Exercise caution when the new Wi-Fi wave strikes

802.11ac has made great strides in improving Wi-Fi performance by using a wider channel, a more efficient modulation mode (by transmitting data in RF waves), and multi-user connections (so-called multi-user MIMO. In fact, this kind of progress will come in a wave in the future.

However, the new 2nd wave chip is different from the 1st wave device (please read the hardware upgrade)

Remember that not all 802.11ac access points are the same. Many access points using the Broadcom chip are limited, for example, they cannot support more than 50 encrypted clients. Broadcom. ac has no onboard CPU, and all Wi-Fi functions are processed by the host (AP's) CPU. This greatly reduces the efficiency, because uninstalling can not make the ap cpu in a low power consumption state.

Vendors have always promised to achieve gigabit speed soon, and you cannot really believe it, because most new features depend on the ability of Wi-Fi access points to manage RF spectrum. Currently, most enterprise-level APS still use general omnidirectional antennas that do not control RF signals.

Frankly speaking, the biggest advantage of 802.11ac is that it operates in 5 GHz frequencies with abundant channel resources-providing MHz bandwidth using 25 non-overlapping channels (in contrast, 3 non-overlapping channels are used to provide only MHz bandwidth in the GHz band ).

High-bandwidth channels are also compatible with 20 MHz or 40 MHz 802.11a and 11n devices. 802.11ac uses an enhanced protection mechanism (RTS/CTS) to dynamically determine whether or not all or only some (such as major 20 MHz, 40 MHz, or 80 MHz) high-bandwidth channels can be used for transmission.

Finally, one fundamental task of IEEE is to maintain backward compatibility with the previous generation of 802.11 protocols. As a technology applicable only to 5 GHz frequencies, 802.11ac supports both 802.11a and 11n frame formats and protection mechanisms, and is fully backward compatible with both.

So we have solved all the problems, right? Not so fast.

Spectrum Efficiency: key to faster 802.11ac

With regards to 802.11ac, vendors will not tell you that when multiple APS use high-bandwidth channels, the spectrum efficiency in the Wi-Fi network is extremely low.

Spectrum efficiency is related to the information rate transmitted in a given bandwidth in a specific communication system. It is a method used to determine the utilization rate of the physical layer protocol on the finite spectrum.

Image Description:

Multi-user MIMO

Simultaneous transmission of multiple downstream links

4x4: 4 Access Points

Data Stream 1

Data Stream 2

Data Stream 3

Data Stream 4

Suppliers will not tell you that faster transmission of modulation technology will only benefit from near-range clients with a high signal-to-noise ratio (advantages that enterprise access points cannot provide. Because the 5 GHz Wi-Fi signal has a small effective range and does not penetrate obstacles like the 2.4GHz signal, the range is also a problem.

Therefore, the focus is to find 802.11ac products with the following features: Focus on RF signals, increase the gain and expand to achieve higher data and modulation rates. The ability of the Wi-Fi system to adapt to changing environments and different client types greatly increases the possibility of full use (which makes 802.11ac very attractive to enterprises ).

Finally, remember that the generation of 802.11ac is costly-and costly. This cost is not only for access points, but also for new PoE switches with higher power 802.3at standards, which are required by the new 802.11ac AP.

Signal path control greatly improves the value of 802.11ac

To make 802.11ac more effective, it is necessary to improve the signal path control capability in the RF spectrum.

Taking the transition from 802.11g to 802.11n as an example -- the latter introduced multi-Wi-Fi RF Link (MIMO ), that is, the new PHY rate, space reuse, and frame merging have been confirmed. This also applies to companies switching from 802.11n to 802.11ac.

For example, with Adaptive Antenna Control per packet, polarization diversity, and active channel selection technology, Smarter Wi-Fi AP and 802.11 maximize the potential of 256-QAM. This means:

● Large SNR/SINR increases the range of useful downstream links in 256-QAM.

● Adaptive polarization diversity combined with the maximum merging ratio (PD-MRC) and higher uplink receiving sensitivity, increased the uplink range of 256-QAM, and

● AP can select channels with larger capacity, lower noise, and less interference

33% gain (1.3x): 33% gain (1.3x)

As channel bandwidth increases, from 20 MHz to 40 MHz, 80 MHz or even 160 MHz, it is increasingly difficult to determine the optimal channel bandwidth suitable for each environment based on Spectrum reuse, AP quantity, transmission power, client device type, and channel support.

The actual traffic statistical modeling is used to determine the available maximum capacity channels, and the Prediction channel selection is used to deal with these problems. Prediction channel selection helps 802.11ac:

● Understand the most suitable channel for binding at any given time,

● Change the channel accordingly based on changes in environmental conditions,

● Find the optimal channel settings based on the client type and quantity, channel bandwidth support, and the total traffic set for each bandwidth.

Finally, when multiple users initiate MIMO attacks, an access point must be installed to direct the Wi-Fi signal to each client for better signal distribution. This can generate a higher-speed continuous data rate and increase the client capacity, because users can log on and exit the Wi-Fi network more quickly, with fewer packet loss and restrictions.

Adaptive or smart antennas will bring great value to any 802.11ac deployment. Without clear RF control, 802.11ac performance will be severely restricted.

Because adaptive antennas always direct Wi-Fi signals to the path as fast as possible at any given time, they provide better spectrum efficiency-the ability to transmit larger frames, extended advanced modulation technology and higher level of SNR/SINR.

Theoretically, the 802.11ac protocol is promising. However, in the final analysis, the best way to increase the capacity to speed up data transmission will require a more advanced RF management method. Without it, everything is a waste of time and money.