Modern wireless internet feels magical: you turn on your laptop, and websites open instantly. However, behind this magic lies a complex process of converting digital data into radio waves, called modulation. It's the choice modulation type It depends on how fast your gigabytes will fly and how stable your connection will be in noisy conditions.
The question of "what modulation is used in Wi-Fi?" doesn't have a single, simple answer, as technology has evolved over decades. From the simplest low-speed schemes to the most complex mathematical algorithms in the Wi-Fi 6E standard—all these represent different approaches to information packaging. Understanding these processes will help you properly configure your router and understand why the signal is excellent in one room, while video freezes in another.
In this article, we'll take a detailed look at the evolution of signal encoding methods and explain the difference between quadrature amplitude modulation and orthogonal frequency division multiplexing. You'll learn why older devices can slow down the entire network and how new standards enable theoretical speeds of several gigabits per second.
Basic principles of data transmission over a radio channel
Before delving into complex abbreviations, it is necessary to understand the essence of the process. Modulation Modulation is the modification of the parameters of a carrier sinusoid (radio wave) to encode information within it. Imagine the carrier frequency as the pure sound of a tuning fork, and the modulation as your hand, which alternately lowers the sound and then changes its pitch, thus transmitting a signal in Morse code.
In the world of Wi-Fi, three main parameters of a sine wave are most commonly used: amplitude (signal strength), frequency, and phase. By combining changes in these parameters, engineers have learned to transmit not just dots and dashes, but entire streams of bits. The more states a wave can assume in a single clock cycle, the more data can be transmitted, but the higher the requirements for reception quality.
- 📡 Amplitude modulation changes the signal strength, which is easy to implement, but is highly susceptible to interference.
- 🔄 Phase modulation shifts the wave in time, which is more resistant to noise, but requires complex equipment.
- 📊 Combined methods They use both amplitude and phase simultaneously, which allows for a multiple increase in channel capacity.
It's important to note that wireless networks are extremely unstable environments. Walls, microwaves, neighbors' routers, and even aquariums can all affect the signal. Therefore, modern standards such as IEEE 802.11ac And IEEE 802.11ax, use adaptive algorithms. The router constantly evaluates the connection quality with the client and dynamically (on the fly) switches the modulation scheme to a faster or, conversely, more reliable one.
Evolution of modulation schemes: from BPSK to 1024-QAM
The history of Wi-Fi development is a race to find the most bits that can be "packed" into a single symbol. The earliest standards, such as 802.11b, used simple binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK). These methods transmitted only one or two bits of information per symbol, respectively. This provided low speed but excellent range and penetration.
With the advent of 802.11g and 802.11n, quadrature amplitude modulation (QAM) came into the picture.QAM). This is a revolutionary method that encodes information in both the amplitude and phase of a signal simultaneously. If we represent this graphically on a phase diagram, the signal points are arranged in a grid. The more points in the grid, the more bits a single symbol carries.
⚠️ Attention: Using high modulation orders (such as 256-QAM or 1024-QAM) requires ideal reception conditions. If you're far from the router or in a room with many concrete walls, the device will automatically switch to a lower modulation order, which will reduce speed but maintain the connection.
The modern Wi-Fi 6 (802.11ax) standard has been implemented 1024-QAMThis allows for the transmission of 10 bits of data per symbol, which is 25% more efficient than 256-QAM in the Wi-Fi 5 standard. However, for this mode to work, the signal strength must be very high and the noise level must be minimal. This is why the advertised gigabit speeds are often only achievable within a single room.
There's a direct correlation between distance and the chosen scheme. While you're standing close to the access point, the client device operates at the limit of its capabilities (1024-QAM). Take a few steps into the hallway, and the router will switch to 256-QAM or 64-QAM. This is normal behavior, called Adaptive Modulation and Coding (AMC).
OFDM Technology: The Basis of Modern Speeds
When talking about what modulation is used in Wi-Fi, it is impossible not to mention OFDM (Orthogonal Frequency Division Multiplexing). This is not just a modulation type, but a multiple access method that became the foundation for 802.11a/g/n/ac/ax. OFDM works by dividing a single high-speed data stream into multiple parallel low-speed streams transmitted on different subcarrier frequencies.
Why is this so important? Imagine you need to transport cargo. You could load it into one huge truck (one carrier frequency) and drive it along the highway. If the road is bad, the cargo will suffer. Or you could distribute the cargo among hundreds of small trucks (subcarriers) and run them in parallel. If one truck gets stuck, the others will make it. In Wi-Fi, this effectively combats multipath propagation, when radio waves bounce off walls and arrive at the receiver with a delay.
In the Wi-Fi 6 standard, the technology has been improved to OFDMA (Orthogonal Frequency Division Multiple Access). The main difference is that OFDMA allows subcarriers to be allocated to different clients simultaneously. A router can allocate part of the frequency resource to your smartphone for downloading emails, and another part to your TV for 4K streaming, all at the same time.
The number of subcarriers in a channel depends on the bandwidth. Wi-Fi 5 used 64 subcarriers for a 20 MHz channel. Wi-Fi 6 increases this number to 256 subcarriers for the same bandwidth, which reduces the "step" between frequencies and allows for more efficient use of the spectrum. This is especially critical in apartment buildings, where the airwaves are clogged with neighboring signals.
Comparison of standards and coding methods used
To better understand the performance differences, let's look at how technologies have evolved from generation to generation. Each new Wi-Fi standard brought not only increased channel bandwidth but also more efficient modulation schemes. This allowed for the maximum extraction of the available radio spectrum.
Below is a table showing the evolution of maximum modulation order and theoretical efficiency in various wireless communication standards.
| Wi-Fi standard | Year of release | Max. modulation | Bits per symbol | Key feature |
|---|---|---|---|---|
| 802.11b | 1999 | CCK / QPSK | 1-2 bits | Operation in the 2.4 GHz band |
| 802.11g | 2003 | 64-QAM | 6 bits | Implementation of OFDM |
| 802.11n (Wi-Fi 4) | 2009 | 64-QAM | 6 bits | The emergence of MIMO |
| 802.11ac (Wi-Fi 5) | 2013 | 256-QAM | 8 bits | 5 GHz range, width up to 160 MHz |
| 802.11ax (Wi-Fi 6) | 2019 | 1024-QAM | 10 bits | OFDMA and BSS Coloring Technology |
As can be seen from the table, the jump from 64-QAM to 256-QAM and further to 1024-QAM provides a significant increase in speed even without expanding the frequency channel. However, backward compatibility forces modern routers to support older, slower encryption methods so that legacy devices like smart light bulbs and early smartphones can connect to the network.
It is also worth mentioning Coding Rate (coding coefficient). Some of the transmitted data is not useful information, but rather correction codes (FEC), which allow for the recovery of lost bits without retransmission. At higher modulations, the payload portion is higher, but the risk of error also increases, so balancing speed and reliability always remains a challenge for router algorithms.
The influence of noise and interference on the choice of modulation
Ideal conditions for Wi-Fi operation do not exist. In the real world, the signal is affected by many factors that force the system to downgrade its modulation order. The main enemy is interference—the overlapping of signals. This could be caused by a neighboring router operating on the same channel, or by household appliances such as microwave ovens, cordless phones, and Bluetooth headsets.
When the noise level (SNR — Signal-to-Noise Ratio) drops, the receiver can no longer distinguish subtle differences between signal states in complex schemes like 1024-QAM. The points on the phase diagram "float" and merge. At this point, a protection mechanism is activated: the router and client device negotiate a coarser, but more reliable modulation, for example, QPSK or BPSK.
Multipath also plays a significant role. The signal reflects off furniture, walls, and the floor, arriving at the antenna from different directions with varying delays. In older systems, this caused signal attenuation. In modern OFDM systems, a guard interval helps filter out reflected signals. However, if delays are too high (for example, in long corridors or large warehouses), modulation efficiency drops again.
⚠️ Attention: Using metal objects in close proximity to the router's antennas can cause strong reflections and multipath, which will lead to constant switching of modulation schemes and "fluctuating" internet speed.
Practical setup and selection of channel width
Although you can't directly select "256-QAM modulation" in your router settings (it's done automatically), you can influence the conditions under which it operates. The key parameter here is channel width. Standards allow for channels of 20, 40, 80, and even 160 MHz.
The wider the channel, the more data can be transmitted, but the higher the noise level and the higher the risk of interception by neighbors. In the 2.4 GHz band, it is advisable to use only 20 MHzAttempting to set 40 MHz in this range in an apartment building is almost guaranteed to result in interference and a drop in actual speed, despite the use of high modulations.
The situation is different in the 5 GHz band. There's more available space here, so to achieve maximum speeds (where 256/1024-QAM works), it's recommended to set the channel width 80 MHz or 160 MHzHowever, if the distance to the router is large, a narrow channel of 20 or 40 MHz may prove more stable, since the signal energy density per hertz of width will be higher.
☑️ Checking conditions for high modulation
To configure these settings, you usually need to log into the router's web interface. The path often looks like this: Settings → Wi-Fi → Basic Settings → Channel WidthIt's worth experimenting here: if the speed is unstable with automatic settings, try manually setting the channel width.
The Future of Modulation: Wi-Fi 7 and 4096-QAM
Technology does not stand still, and the standard infrastructure is already being deployed today Wi-Fi 7 (802.11be)The main innovation here is modulation. 4096-QAMThis means that 12 bits of information are encoded in a single symbol. Compared to 1024-QAM, this provides an additional 20% increase in data transmission speed.
However, the signal quality requirements for 4096-QAM are even more stringent. For this modulation to work, the device must be in near line-of-sight with the access point. Furthermore, Wi-Fi 7 introduces MLO (Multi-Link Operation), which allows devices to transmit data simultaneously across different bands (2.4, 5 and 6 GHz), aggregating bandwidth and reducing latency.
Do you need Wi-Fi 7 right now?
Currently, there are very few Wi-Fi 7-enabled devices on the market, and routers are expensive. Unless you need to transfer large amounts of data within your local network (for example, editing 8K video), the current generation of Wi-Fi 6/6E is sufficient for comfortable internet use, streaming, and gaming.
The implementation of new modulation schemes is limited not only by hardware but also by power consumption. Processing 4096-QAM signals requires significant computing resources, which can drain smartphone batteries faster. Therefore, mobile devices will prioritize balancing energy efficiency with maximum speed.
Frequently Asked Questions (FAQ)
Is it possible to manually enable 1024-QAM in the router settings?
No, you can't directly enable a specific modulation type (for example, force the router to operate only at 1024-QAM). The modulation scheme is selected dynamically during the handshake between the router and the client device. They evaluate the signal quality (SNR) and select the highest possible modulation order that ensures a stable connection. Mandatory restriction is only possible in the engineering menus of professional equipment, but this is not available for consumer networks.
Why is my Wi-Fi speed lower than what is stated in the router specifications?
The advertised speed (for example, AC1200 or AX3000) is the theoretical maximum achievable under ideal laboratory conditions using the given modulation, using the sum of all antennas and bands. In reality, speed is reduced by distance, walls, interference from neighbors, the half-duplex nature of Wi-Fi (when a device cannot listen and talk simultaneously), and protocol overhead. Actual speed is typically 50-60% of the theoretical speed.
Does an old smartphone affect the overall Wi-Fi speed?
An older client shouldn't throttle the speed of other modern devices if the router's Airtime Fairness feature is enabled. This feature limits the amount of time a slow device can spend on the air. Without this feature, an older device using a lower modulation (such as 802.11g) will spend longer on the air to transmit the same amount of data, indirectly slowing down the overall network.
Is there a difference in modulation between the 2.4GHz and 5GHz bands?
Yes, there is. The 2.4 GHz band is noisier and has fewer non-overlapping channels, so it uses higher modulation orders less frequently over long distances. The 5 GHz (and 6 GHz) band allows for wider channels and higher modulation orders (256/1024-QAM) thanks to better interference immunity and a wider spectrum, resulting in significant speed gains.