When it comes to local networking and wireless LAN, most people are interested in its speed. With Wi-Fi 6 or IEEE 802.11ax, the next standard for new access points is already on the market. Along with higher data throughput per Wi-Fi client, it promises greater efficiency especially in high-density environments. In theory this is an exciting development. But let’s do a fact check and examine whether a Wi-Fi infrastructure based on an entry-level Wi-Fi 6 access point with 2×2 MIMO has any advantages over a mid-range Wi-Fi 5 installation with 3×3 MIMO. We can do a direct comparison.
It’s all about the frequency
The Wi-Fi 5 standard operates solely in the 5-GHz band. Wi-Fi 5 access points are usually equipped with two radio modules. They can supply Wi-Fi to end devices in both the 5-GHz and 2.4-GHz frequency bands at the same time. The pitfall here is that Wi-Fi 5 does not support the 2.4-GHz frequency band. If you invest in a Wi-Fi 5 infrastructure, support for clients in the 2.4-GHz frequency band is therefore only possible by using the previous standard Wi-Fi 4.
This is where Wi-Fi 6 scores points: This standard operates in both the 5-GHz and 2.4-GHz frequency bands.
Bandwidth of the end devices
When it comes to the effective Wi-Fi bandwidth available to individual end devices, a key factor is the number of antennas built into the wireless clients and thus the number of viable MIMO streams.
Market figures for the latest end devices show:
Today around 65% of Wi-Fi users have end devices with just one antenna. Thus the majority of end devices available today (smartphones, cheaper tablets) are single-stream Wi-Fi clients.
Around 30% of Wi-Fi users use devices that support up to two streams. These dual-stream Wi-Fi clients are often high-end laptops and tablets.
Indeed, only about 5% of all Wi-Fi users have devices that support up to three streams. So only a few end devices, such as high-end laptops for the gaming sector or high-performance applications are able to process three MIMO data streams. Most networks rarely need to serve this type of Wi-Fi client. In practice, therefore, only very few clients make full use of the bandwidth of a 3×3 MIMO Wi-Fi 5 access point.
More bandwidth per stream
Compared to Wi-Fi 5, Wi-Fi 6 offers significantly higher throughput per stream.
An example: With a channel width of 80 MHz, a Wi-Fi 6 access point can achieve up to 600 Mbps gross per stream while a Wi-Fi 5 access point can only achieve up to 433 Mbps. You can’t ignore the clear speed advantage of Wi-Fi 6—a gain in gross data throughput in the double-digit percentage range!
A Wi-Fi 5 access point with three streams achieves a gross total throughput of up to 1.3 Gbps (3x 433.3 Mbps), and even with just two streams, a Wi-Fi 6 access point achieves up to 1.2 Gbps (2x 600 Mbps)—almost the same speed.
Less congestion in the radio field
Due to technologies defined in the standard, a conventional Wi-Fi 5 access point with 3×3 MIMO can only serve one 3×3 client, one 2×2 client, or two 1×1 clients at the same time. Wi-Fi 6 uses the radio field more efficiently: The newly introduced and optional orthogonal frequency division multiple access (OFDMA) introduces subcarriers with a width of 2 MHz that can be spread across 20, 40 and 80 MHz channels. With OFDMA, each 20-MHz slice can serve up to 9 users simultaneously. This allows Wi-Fi channels to be utilized far more effectively. Just imagine a car pool: Large numbers of cars with a single occupant (Wi-Fi 5) will cause heavy traffic, while fewer, multi-occupant cars (Wi-Fi 6) can travel faster.
An eye on future viability
Although there aren’t so many Wi-Fi 6 clients around right now, it won’t stay that way for long. The introduction of this standard and the latest devices will inevitably cause a significant increase in their number over the next few years. As a consequence for wireless infrastructures, Wi-Fi 5 access points will become technologically obsolete within the next two to four years at the latest. This becomes even clearer considering that the next standard Wi-Fi 7 is already in planning. So when planning the network, you cannot ignore the fact that even future end devices may not be supported with high performance levels.
When comparing the standards, Wi-Fi 6 offers a list of valuable functions that are not supported by Wi-Fi 5. These include features like MU-MIMO, which Wi-Fi 6 supports in both the downlink and uplink (UL MU-MIMO). This is advantageous in environments with large numbers of Wi-Fi users and bandwidth-hungry real-time applications, as it also improves latency and throughput.
Further beneficial features are the OFDMA mentioned above, modulation has increased from QAM-256 to QAM-1024, battery life on the client side is extended with target wake time (TWT), and there is the new basic service set coloring (BSS coloring) with spatial re-use.
To sum it up
Wi-Fi 5 access points with 3×3 MIMO offer the chance of higher overall throughputs only in wireless environments where numerous high-end 3-stream devices are operated.
In any other environment, Wi-Fi 6 with 2×2 MIMO has the edge. Another point in favor of Wi-Fi 6 is that users of the 2.4-GHz band do not benefit from the Wi-Fi 5 standard at all. The technology improvements and new features available since the introduction of Wi-Fi 6 underline once again that, when upgrading your infrastructure, the latest standard offers many advantages.
The author Joachim Prick is Product Manager Wi-Fi at LANCOM Systems.