WiFi Communication: From Principle to Future

1. Basic Concepts of WiFi Communication

WiFi communication is a wireless local area network technology that enables electronic devices to connect to the Internet wirelessly. WiFi technology mainly communicates based on radio waves, and its working principle can be divided into two major parts: the physical layer and the MAC layer. At the physical layer, WiFi communication uses radio waves in the 2.4GHz or 5GHz frequency band to transmit data. The data is converted into radio wave signals and undergoes a series of modulation, demodulation, and encoding processes to adapt to wireless transmission. At the MAC layer, WiFi devices have a unique MAC address for identifying the device in the network and define the standards for data transmission, such as how to transmit data, ensure data reliability, and handle network congestion.

2. Development and Standards of WiFi Communication

1. Development of WiFi Communication

Development History:

2. Key Technology Development

• MIMO (Multiple Input Multiple Output) Technology: Transmits and receives data through multiple antennas to improve transmission rate and stability.
• Channel Bonding Technology: Combines multiple wireless channels into a wider channel to improve transmission rate.
• Spatial Stream Technology: Distributes data to multiple antennas for transmission using multiple independent transmission paths to improve throughput and performance.

3. Standards of WiFi Communication

Main Standards:

Standard Naming:

• WiFi 4: Corresponds to the 802.11n standard
• WiFi 5: Corresponds to the 802.11ac standard
• WiFi 6: Corresponds to the 802.11ax standard
• WiFi 7: Corresponds to the 802.11be standard

3. Application Scenarios of WiFi Communication

WiFi communication technology, as a wireless communication technology, has been widely used in modern society. The following are some typical application scenarios:

1. Home Applications

• Smart Home Control: Users can connect various smart devices such as smartphones, tablets, smart TVs, etc. via WiFi to achieve smart home control and data sharing. For example, control the switch of smart light bulbs and adjust the temperature of smart air conditioners through a mobile app.
• Home Network Sharing: Multiple devices in a home can wirelessly connect to the same WiFi network to share files, audio, video and other resources, realizing interconnection. Family members can conveniently use the Internet in each room without worrying about wiring problems.

2. Office Applications

• Employee Network Access: Deploying WiFi in the office allows employees to conveniently access the company network for file transfer, video conferencing and other operations, improving work efficiency.
• Enterprise Office Equipment Connection: Whether it is enterprise office equipment or home entertainment equipment, very few are equipped with SIM card slots at the factory and cannot directly support connection to 4G or 5G. Most of the time, a 5G CPE is used to receive a local Wi-Fi signal. And the new generation of Wi-Fi 6 reduces frequency interference and improves network efficiency and capacity, ensuring 5G signals for multiple concurrent users and guaranteeing network stability when the number of conversions increases.

3. Public Place Applications

• Free WiFi in Public Places: The deployment of WiFi in coffee shops, airports, libraries, shopping malls, hotels and other public places can attract more customers and meet the Internet access needs of a large number of users.

4. Internet of Things Applications

• Connection of Smart Home Devices: The control of household appliances such as smart audio systems, smart window systems, and smart air conditioning systems can all be achieved through WiFi communication. By connecting various devices to the WiFi network, remote control and intelligent management of the devices can be realized, improving the convenience and intelligence level of life.
• Data Transmission of Internet of Things Devices: In the field of the Internet of Things, the WiFi module serves as an information bridge, connecting various sensors with data centers to realize real-time data collection, transmission, and analysis, providing strong support for smart cities, Industry 4.0, and so on. For example, in a temperature sensing application, the temperature sensor generates a voltage that changes with the temperature. Then, the built-in ADC converts the voltage into a digital quantity. The WiFi module will actively report the data through the wireless network, enabling timely perception of the body temperature of patients. Based on the real-time transmission and reception of data, all-weather intelligent monitoring in medical scenarios can be achieved to ensure the health and safety of patients.
• Industrial Production and Manufacturing Scenarios: The large bandwidth and low latency features of Wi-Fi 6 have expanded the application scenarios of Wi-Fi from enterprise office networks to industrial production scenarios, such as ensuring the seamless roaming of factory AGVs and supporting the real-time video acquisition of industrial cameras. Moreover, devices can support more Internet of Things protocols through external card insertion methods, realizing the integration of the Internet of Things and Wi-Fi and saving costs.

5. Other Applications

• Intelligent Security: Whether in the traditional analog monitoring field or the emerging network monitoring field, wired transmission has always dominated. However, with the development of the network, the requirements for monitoring ranges and scenarios are becoming more and more complex. The WiFi wireless transmission mode, with its own irreplaceable advantages, is playing an increasingly important role in the security industry, making up for the deficiencies of the wired transmission mode.
• Education Field: Schools can deploy WiFi to facilitate students' online learning and data retrieval, improving the quality of teaching.
• Medical Field: In intelligent medical care, WiFi technology can help medical devices connect to the hospital network, realizing remote monitoring and diagnosis.
• Smart City: In a smart city, WiFi technology can be used for intelligent transportation and public security.

4. Functions of the Physical Layer and MAC Layer in WiFi Communication

• Functions of the Physical Layer in WiFi Communication: The physical layer in WiFi communication is responsible for ensuring that the original data can be transmitted on various physical media. Its specific functions include defining the physical characteristics such as the type, voltage, and frequency of the transmission medium, defining the encoding format of the data, and defining the protocols for data transmission. The protocols of the physical layer include electrical characteristics, mechanical characteristics, and operational characteristics. Together, they ensure that no errors occur during the transmission of data on the physical medium and provide a physical connection so that computers can be physically connected to the network.

• Functions of the MAC Layer in WiFi Communication: The MAC layer in WiFi communication is responsible for controlling the transmission of data packets on the physical medium. Its specific functions include adding a frame header and a frame trailer to data packets, accessing data on the physical medium, resolving multiple access conflicts, and providing traffic control. The protocols of the MAC layer include CSMA/CD (Carrier Sense Multiple Access with Collision Detection), ALOHA (Random Access), TDMA (Time Division Multiple Access), and FDMA (Frequency Division Multiple Access). These protocols help to effectively manage the transmission of data packets on the shared medium, avoid conflicts, and ensure the smooth operation of the network.

In a Wireless Local Area Network (WLAN), the standard of the MAC layer is IEEE 802.11, and its working mode adopts DCF (Distributed Coordination Function) and PCF (Point Coordination Function). DCF is based on the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) protocol, allowing devices to listen to the channel before sending data. Only when the channel is idle can the transmission begin. PCF is a centralized control method, where a central point controls the access to the channel to improve network efficiency.

5. Technological Advances of the 802.11be Standard

The 802.11be standard, also known as Wi-Fi 7, represents a significant leap in Wireless Local Area Network (WLAN) technology. This standard aims to significantly increase the data transmission rate, reduce latency, and enhance the overall network reliability. The following are some of the key technological advances of the 802.11be standard:

1. Higher Data Transmission Rate

The theoretical peak rate can reach above 46.1Gbps: The theoretical peak rate of 802.11be is nearly four times higher than that of the previous generation standard (such as Wi-Fi 6). This improvement is due to the use of a larger bandwidth, higher-order modulation techniques, and more spatial data streams. For example, the maximum bandwidth has been increased from 160MHz to 320MHz, and the modulation technique has been upgraded from 1024-QAM to 4096-QAM.

2. Lower Latency

Latency reduced to the millisecond level: By introducing multi-link operation (MLO), improved multi-user multiple input multiple output (MU-MIMO) technology, and orthogonal frequency division multiplexing access (OFDMA), 802.11be has significantly reduced network latency. These technologies work together to ensure a smoother experience for real-time applications such as online games and video calls.

3. Larger Network Capacity

Support for MU-MIMO with up to 16 spatial streams: 802.11be has expanded the MU-MIMO technology from 8 spatial streams to 16, greatly increasing the network capacity. This means that more devices can be connected to the network simultaneously, and each device can have a fast connection speed, thus solving the network congestion problem in high-density environments.

4. Wider Coverage Range

Adoption of a wider channel range and advanced antenna technology: By using a wider channel range and advanced antenna technology, 802.11be provides a better wireless coverage range. Even in larger areas, users can enjoy a more reliable and stable wireless connection without having to worry about signal strength attenuation.

5. More Efficient Spectrum Utilization

Preamble Puncturing and Multi-RU Technologies: To improve spectrum utilization efficiency, 802.11be has introduced Preamble Puncturing and Multi-RU (Multiple Resource Unit) technologies. These technologies allow for more flexible use of spectrum resources, thereby improving the overall network performance. For example, in the presence of interference, the Preamble Puncturing technology can avoid the interference by "puncturing" and continue to transmit information.

6. Multi-link Operation (MLO)

Simultaneous use of multiple frequency bands for data transmission: MLO allows multiple links to simultaneously transmit and receive data, thereby improving the overall throughput and reliability of the network. By intelligently managing and distributing traffic, MLO can work simultaneously on different frequency bands (such as 2.4GHz, 5GHz, and 6GHz) to optimize network performance.

7. Higher-order Modulation Technology (4096-QAM)

Each symbol carries more information: The 4096-QAM modulation technology enables each symbol to carry 12 bits of information. Compared with the 1024-QAM of Wi-Fi 6 (each symbol carries 10 bits), the information carrying capacity is increased by 20%. This helps to achieve a higher data transmission rate under the same bandwidth.

8. Extended Multiple Input Multiple Output (EMIMO)

16×16 MIMO configuration: 802.11be supports a 16×16 MIMO configuration, meaning that there are 16 antennas at both the transmitting end and the receiving end. This configuration not only improves the theoretical transmission rate but also supports the simultaneous access of more devices, enhancing the robustness of the network.

9. Separation of Data and Control Planes

Improved management efficiency: By transmitting data and control information on different frequency bands, 802.11be reduces the latency caused by the transmission of control information and improves the management efficiency of the network. This enables more frequent and reliable updates of control information, thereby optimizing network scheduling and throughput.

10. Enhanced Link Adaptation and Retransmission Protocol

Hybrid Automatic Repeat Request (HARQ): The HARQ mechanism allows the receiving end to combine previously unsuccessful decoding transmissions with subsequent retransmissions, thereby improving the decoding success rate. This mechanism has been verified in cellular systems and is now introduced into the Wi-Fi system to enhance reliability and reduce latency.

These technological advances jointly promote the development of the 802.11be standard, making it an ideal choice for supporting future high-bandwidth, low-latency applications. Whether it is high-definition video streaming, virtual reality, or large-scale Internet of Things deployments, 802.11be demonstrates great potential and advantages.

6. New Features of the WiFi 7 Standard

WiFi 7, namely IEEE802.11be, also known as EHT (Extreme High Throughput), has many new features compared to its predecessors, mainly including the following aspects:

1. Frequency Band Expansion

• Inclusion of the 6GHz Frequency Band: Based on 2.4GHz and 5GHz, WiFi 7 incorporates the 6GHz frequency band dedicated to WiFi 6E into the regular frequency bands, further expanding the spectrum resources and providing a basis for achieving higher data transmission rates.

2. Bandwidth Enhancement

• 320MHz Channel Bandwidth: The channel bandwidth of WiFi 7 has been increased from 160MHz of WiFi 6 to 320MHz, and the 320MHz bandwidth can only be used in the 6GHz frequency band. This significantly increases the data transmission rate and can better meet the needs of high-speed data transmission such as high-definition video and large file downloads.

3. Modulation Method Upgrade

• 4096-QAM Modulation: WiFi 7 adopts the 4096-QAM modulation method, while WiFi 6 uses 1024-QAM. The 4096-QAM modulation can carry 12 bits of information per symbol. In contrast, the 1024-QAM can only carry 10 bits of information per symbol. This feature alone can further increase the throughput of WiFi 7 by about 20%, thereby improving the spectrum efficiency and increasing the amount of data transmission.

4. Multi-link Aggregation

• Parallel Use of Multiple Physical Links: A single WiFi 7 device can use multiple physical links in parallel. These links can be in different frequency bands, such as a dual-link of 2.4G and 5G, or multiple links in the same frequency band, such as a dual-link of 6G and 6G. Through this method, the throughput can be effectively increased, and the latency can be reduced, improving the smoothness and stability of the network. It is especially suitable for application scenarios with high latency requirements, such as VR games and high-definition video conferences.

5. Lower Latency

• Optimization of Transmission Mechanism: WiFi 7 has optimized the transmission mechanism through a series of technologies, reducing the waiting time and the number of retransmissions during the data transmission process, thereby significantly reducing the latency. This is of great significance for application scenarios with high real-time requirements, such as industrial automation control, remote medical surgery, and autonomous driving, ensuring the timely transmission and accurate response of data and improving the reliability and efficiency of the system.

6. Higher Number of Device Connections

• Enhanced Multi-user Access Capacity: WiFi 7 adopts more advanced multi-user multiple input multiple output (MU-MIMO) technology and orthogonal frequency division multiple access (OFDMA) technology, enabling it to support more devices to connect to the network simultaneously and ensuring that each device can obtain a stable network bandwidth. This allows a large number of smart devices in homes, offices, and other places to connect to the WiFi 7 network simultaneously without network congestion or unstable connections, meeting the needs of device interconnection in the Internet of Things era.

7. Stronger Anti-interference Ability

• Intelligent Spectrum Management: WiFi 7 has more intelligent spectrum management functions. It can monitor the surrounding wireless signal environment in real time, automatically select the optimal frequency band and channel for data transmission, and avoid interference sources. At the same time, it also adopts advanced interference suppression technologies to effectively reduce the interference from other wireless devices, improving the stability and reliability of the network and ensuring good network performance in complex wireless environments.

7. Future Prospects of WiFi Communication

In the future, WiFi communication has a very broad prospect. With the continuous iteration of technology, its transmission rate will further soar to meet the applications with extremely high bandwidth requirements, such as 8K video streaming and ultra-large cloud games. The coverage range is expected to continue to expand, realizing stable connections in a wider area. Meanwhile, the power consumption will be lower, which is beneficial to the long-term power supply of a large number of Internet of Things devices. The security will also be strengthened to comprehensively protect user information and privacy. Moreover, WiFi is expected to be deeply integrated with 5G and other networks to create a seamless, high-speed, and stable full-scenario network, enabling people to enjoy high-quality, convenient, and secure communication services wherever they are.