A lot of people often complain that the Wi-Fi is slow in the world of networks. There are various reasons why the performance of a Wi-Fi network is poor, some of which include:

- Access Points using outdated data speeds like 1 and 2 Mbps

- Too many devices sending data on the same channel

- Access Points transmitting data at a very high power level

- A large number of failed transmission attempts

Now, let's take a closer look at each of these issues!

Access Points using legacy data rates such as 1 and 2 Mbps

Access Points that use older data rates like 1 and 2 Mbps are still in use, even though newer Wi-Fi devices are much faster. This means that Wi-Fi networks still support these slow legacy data rates. As a result, devices that are far from the Access Point may connect at very low speeds, and older devices may also connect at very low speeds. These connections can slow down the entire network.

When troubleshooting slow performance or optimizing a Wi-Fi network, one of the first and easiest things to do is to check the data rates supported by the Access Points. When you select the network you want to test, you should view the list of Access Points on that network and check the supported rates. These rates are measured in Mbps and include 1, 2, 4, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, and 54 Mbps. These rates include both the basic rates that a device must support to connect, as well as extended supported rates.

To improve network performance for all devices, consider disabling the lower rates on your Access Points. However, this should be done carefully to ensure that devices that require those lower rates are still supported. For example, some environments may need to support 802.11b devices that require a 1 Mbps connection rate. But if very old devices are not necessary to support, you can set the lowest rates at 11 or even 24 Mbps. The specific rate to set depends on the density of the Access Points. If the Access Points are far apart, set the minimum rate no higher than 11 Mbps so that devices on the edge of coverage can still connect. If the Access Points are close together, you can set a higher minimum rate, such as 24 Mbps.

Too many devices transmitting on the same channel

One common reason is that the airtime is distributed among all the Wi-Fi devices in the same area and on the same channel. If there are too many devices trying to transmit on the same channel, it will slow down the performance for everyone. To optimize performance, it is important to reduce co-channel interference (CCI), which occurs when there are too many access points on the same channel in the same area.

However, in the 2.4 GHz Wi-Fi band, there is another issue called adjacent channel interference (ACI). In the 2.4 GHz band, adjacent channels overlap with each other, which means that traffic on one channel can disrupt traffic on a nearby channel. It is recommended to use only channels 1, 6, and 11 in the 2.4 GHz band because they are far enough apart and do not overlap. If an access point is on channels 2, 3, 4, 5, 7, 8, 9, or 10, it will overlap and interfere with an access point on channel 6. This is known as adjacent channel interference and can cause more performance issues than co-channel interference. For example, it is better to have three access points on channel 6 than to have one each on channels 4, 6, and 8.

Access points transmitting too high of power level

Your network customer/user is complaining that they are unable to connect to the Wi-Fi network. You visit them in person to understand the issue. When you arrive at their location, you notice that their Wi-Fi device is displaying 4 bars for the network they are trying to connect to. To investigate further, you might even use a signal meter on your phone app to check the actual signal strength of that network in terms of dBm. Everything seems fine. So why can't they connect?

The problem may lie with one of the network's access points (AP) transmitting at a very high power level, which is causing the 4 bars and high dBm readings at the user's location. As a result, the user's device is trying to connect to that specific AP. However, does that AP receive the signal from the user's device? Wi-Fi communication requires both the user's device and the AP to transmit at similar power levels. Ideally, the user's device should detect the strongest signal level from the AP that is closest to them. If you measure the signal level of the user's device at the location of that AP, it should be similar. If you find that the signal level is too weak (e.g., less than -80 dBm) or nonexistent, then there is your problem!

A high retry rate of transmissions

A well-designed network is important for good Wi-Fi connections and high performance. This means having strong coverage, minimal interference, low airtime contention, and good network capacity. When things aren't working well, Wi-Fi devices will send out signals but they won't be received.

When a Wi-Fi device, like an access point or a client, sends out data, it needs to get a confirmation from the receiver. If it doesn't, it will send out the same data again. This is called a retry. The retry rate is the percentage of total data sent that needs to be retried. A high retry rate means that a lot of the airtime is being used (or wasted) because the conditions aren't allowing the transmitted data to be properly received and confirmed.

There isn't a specific standard for what is considered a good or bad retry rate, but if the measured retry rate is over 15%, it's worth looking into other issues like poor signal-to-noise ratio, too many access points or clients on a channel, or high channel usage.

If you want more information on troubleshooting 802.11ac Wi-Fi, you can watch our recorded webinar on Brighttalk.

If you need Switches, Routers, or need more network information, welcome to contact us www.hi-network.com (Email: [email protected])