When it comes to guest complaints, Wi-Fi Internet always hovers near the top. It seems to be a universal theme — regardless of country, chains, or hotels’ star ratings. Let’s exam what are the common causes, and how can we fix hotel Wi-Fi.
Many years ago, a prestigious 5-star hotel in Bangkok was littered with guest complaints on its Wi-Fi Internet. Determined to turn this around, the hotel bit the bullet and overhauled its entire Wi-Fi network. The primary design objective was to have strong coverage everywhere within the hotel. They spent over half a million USD on enterprise-grade 802.11ac Wi-Fi and upgraded their ISP to a 150Mbps dedicated leased line putting its guest Internet among one of the fastest in Bangkok at that time.
The expectation was over the roof, but that quickly turned into disappointments and frustrations; slow Internet was still a common complaint, device roaming was far from seamless, and connectivity issues didn’t completely go away despite brand new hardware and ubiquitous coverage. It turns out that their quest for perfect coverage may have inadvertently hindered performance and leads to poor Wi-Fi experience.
The truth is that it takes more to build a reliable Wi-Fi network than just having the latest equipment and exceptional coverage.
Variables like channel interference, secondary coverage, width, overheads, mounting position, AP/antenna choice, encryption protocol, and even guests’ own devices also play a big part in Wi-Fi performance.
I still noticed many hotels, even renowned international chains, only mandate coverage on their design standards, omitting other critical factors mentioned. To improve guest experience, we must deemphasize on coverage and adopt the big-picture design approach.
I am sorry, but the truth there is really no quick fixes for hotel Wi-Fi Internet. Wi-Fi is a complex technology with many different variables and it’s going to be extremely difficult to get them all right.
So rather than going through them all, I picked out a few factors that will make a huge difference if we get them right. The good news is you don’t need any expensive professional tools; all you need is a Wi-Fi scanner. If you don’t have one, there are many free scanners available for both Windows and Mac. I personally use WinFi for Windows, and if you are a Mac user, I highly recommend Wi-Fi Explorer. There are free and paid versions with advanced features, so make sure you check it out.
#1 Minimize Channel Interference
Wi-Fi communication occurs in channels. As you probably know, Wi-Fi uses two license-free frequency bands — the 2.4GHz and the 5GHz. Channel is essentially a shared, unbounded medium that operates on specific frequencies; and since they are unbounded, overlaps may occur.
Channel interference is a common but serious cause of poor Wi-Fi performance. It cripples capacity, impedes communication, reduces throughput resulting in slow data transfer; so eliminating interference should be the number 1 priority.
Types of Channel Interference
There are three types of channel interference — Co-Channel Interference (CCI), Adjacent-Channel Interference (ACI), and Non-Wi-Fi interference.
CCI occurs when more than one AP operates on the same channel. Wi-Fi is a half-duplex technology; in other words, only one device transmits at a time. A device uses a Clear Channel Assessment (CCA) mechanism to check if a channel is available. If another device is transmitting, it defers its transmission until the channel is cleared. Think of it like in a meeting room; each attendee takes a turn to talk and ask questions. The more the attendees, assuming everyone has something to say, the longer the meeting. Likewise, in a congested channel, many devices are competing for the opportunity to transmit; therefore, it takes longer for every device to transfer data.
ACI, on the other hand, is far worst than CCI and it’s the first thing I look for during a Wi-Fi audit. ACI occurs when multiple APs are using overlapping frequencies. Unlike CCI, where a device defers its transmission if the channel is occupied, devices in an adjacent channel ignore the rule and talks over each other, causing collisions and retransmissions. Generally, we want to keep the retry rate as low as possible, ideally below 10%. To measure retry rate, we need a protocol analyzer like Wireshark or Omnipeek or using inexpensive WLANPi Extcap with Wireshark.
Considered there are only 3 non-overlap 20MHz channels for 2.4GHz band, CCI/ACI is virtually impossible to avoid in a high-density environment like meeting rooms or lobbies. The 5GHz offers a much broader spectrum up to 25 non-overlapping 20MHz channels, but CCI and ACI can still occur without proper planning.
The final type of interference is non-Wi-Fi interference. Appliances like microwaves, cordless phones, baby monitors, Wi-Fi cameras are notorious for causing this type of interference. These devices don’t contend for opportunities to transmit, they just do, so they can potentially bring down the entire Wi-Fi network.
The figure below shows 2.4GHz spectrum with a Wi-Fi camera enabled. Notice how it rendered channel 1 completely unusable and caused interference all the way to channel 8. Unfortunately, non-Wi-Fi interference is difficult to detect without a spectrum analyzer like Ekahau Pro with Sidekick.
We may not be able to eliminate channel interference completely, but there are many ways to ease the impact of interference and fix hotel Wi-Fi. Here are a few: as a rule of thumb, always stick to channels 1, 6, or 11 on 2.4GHz. Carefully review hotel-wide channel usage and make an adjustment accordingly. Optimize TX power to create smaller cells or selectively turn off 2.4GHz radio on a few APs to reduce interference. Lastly, use only 20MHz channels in high-density locations to maximize available channels.
#2 Use 20MHz Channel
Traditionally Wi-Fi uses standard 20MHz channel on 802.11a and 802.11g that supports the maximum data rate of 54Mbps. 802.11n introduces MIMO and the 40MHz channel (bonding two 20MHz channels) that delivers up to 150Mbps per spatial stream. 802.11ac takes this further and adds 80MHz and 160MHz channels that max out at 866.7Mbps. Modern devices are capable of doubling or even tripling their data rate depending on the number of spatial streams. Check out the MCS Index Chart for data rates for each configuration.
Of course, we want to maximize the data rate, but we need to be careful not to fall into the speed trap. Firstly, channel bonding isn’t feasible in the 2.4GHz band. With only 3 non-overlapping channels, bonding multiple channels almost guarantee interference. As a rule of thumb, do not use 40MHz channels in the 2.4GHz spectrum.
Secondly, bear in mind that channel bonding results in higher noise. For each bond, we lose 3dBm of SNR, and it affects the quality of the signal. Low SNR leads to data corruption and retransmissions. That said, bonded channels have a shorter effective range compared to the standard 20MHz channel.
Channel bonding also reduces available non-overlapping channels, especially in the high-density AP deployment. It’s true that the 5GHz is a much wider spectrum, and with careful planning, channel bonding can boost performance; however, we may not be able to use all the available channels. For instance, out of 25 5GHz channels in the U.S., 16 are DFS channels, which we may not be able to use. The remaining 9 channels are only enough to form four 40MHz or two 80MHz channels. That said, it’s probably more beneficial to break an 80MHz channel into four 20MHz channels in a high-density environment. This effectively expands Wi-Fi capacity, accommodates more devices, and reduces interference.
And in contrary to popular belief, the 20MHz channel is plenty fast for general Internet usage. It delivers up to 80Mbps of actual data throughput e.g. from a speed test or Fast.com. Another consideration is, if a hotel caps individual device bandwidth below 80Mbps, bonding channels become pointless.
#3 Enable Band Steering
To make it easy for guests to connect to Wi-Fi Internet and avoid unnecessary confusion, many hotel chains adopt the single SSID standard for both 2.4GHz and 5GHz. In other words, guests have no option to pick and choose which band to connect. It’s entirely up to the client device, not the AP, to select which band to connect. Clients use several matrics, for example, RSSI, SNR, and MCS to evaluate their options. Very often, clients opt for the BSSID with the higher received signal; this gives an edge to the 2.4GHz because of its longer wavelength and higher penetration. This worsens the performance with too many clients connecting to the already crowded 2.4GHz space.
With band steering enabled, AP checks the client’s probe request frames and determine if it supports 5GHz; if so, the AP sends only probe responses on 5GHz enticing the client to connect to the 5GHz band. The idea is to steer 5GHz capable clients to that band and free up 2.4GHz for legacy devices.
Hotels often receive bad raps for their poor Wi-Fi Internet, but to be fair, managing the guest Internet experience is difficult. With many variables, Wi-Fi by nature is complex, but having to accommodate heterogeneous devices makes the hotel environment even more challenging. Remember, Wi-Fi performance is all about sharing airtime, guests with slow devices will have a profound impact on the performance of the rest; so if we can maximize channel re-use, and effectively manage device allocations, we stand a better chance of getting a high mark in guest score.
It’s not a coincidence that a great Wi-Fi experience starts from a well-thought-out design. We must consider all the factors that make up Wi-Fi experience, not just coverage. Those are definitely not easy, but that’s the only way we can deliver a quality Wi-Fi Internet service to our guests.