Key Indicators for Selecting WiFi Modules

　　However, there are many types of WiFi modules on the market, each differing in performance parameters, functional features, and applicable scenarios. If the appropriate WiFi module is not selected during product development or device upgrades, it may lead to a series of problems. For example, if the transmission rate is too low, it may cause video stuttering and slow file transfers, severely affecting user experience; insufficient signal coverage may lead to frequent disconnections in larger spaces or complex environments, preventing stable operation; excessive power consumption can shorten the device’s battery life, which is undoubtedly a fatal flaw for battery-powered mobile devices; and poor compatibility may cause conflicts between the WiFi module and other components of the device, leading to malfunction or even hardware damage. Therefore, the selection of WiFi modules is by no means a trivial matter; it directly relates to the product’s performance, stability, user experience, and market competitiveness, requiring us to take it seriously, conduct in-depth research, and make cautious choices.

　　Key Indicators for Selecting WiFi Modules

1、Transmission Rate

　　The transmission rate is one of the important indicators for measuring the performance of WiFi modules, directly affecting the speed of data transmission. The requirements for transmission rates vary in different application scenarios. For example, in a home network environment, if it is only used for browsing web pages, sending and receiving emails, and other daily office and light entertainment activities, generally, a WiFi module with a transmission rate of 150Mbps-300Mbps can meet basic needs; however, if high-definition video streaming, large file downloads, or online gaming, which require high bandwidth, are frequently performed, then at least a WiFi module with a transmission rate of 600Mbps or higher should be chosen to ensure a smooth experience and avoid issues like video stuttering and high latency in games.

　　In the field of industrial control, for some real-time data collection and transmission scenarios, such as sensor data transmission in automated production lines and power data monitoring in smart grids, a higher transmission rate may be required to ensure timely and accurate data transmission. In this case, a 1Gbps or even higher WiFi module would be more appropriate. In scenarios where data transmission volume is not large but real-time performance is extremely critical, such as in smart home devices like smart locks and smart switches, although the amount of data transmitted is small, the requirement for rapid signal response to achieve instant switch control means that these devices have relatively low requirements for transmission rates, generally a few dozen Mbps of rate can suffice for normal operation.

　　Currently, common transmission rate standards for WiFi modules on the market include 802.11n, 802.11ac, and 802.11ax (Wi-Fi 6). The theoretical maximum transmission rate of 802.11n can reach 600Mbps, but in actual use, it is generally around 150Mbps-300Mbps due to environmental factors; 802.11ac supports higher transmission rates, with a single band maximum rate of over 1.3Gbps in the 5GHz band, meeting the needs of most home and office scenarios for HD video streaming and large file transfers; while Wi-Fi 6, as the new generation of WiFi standards, offers higher transmission rates and efficiency, with a theoretical maximum transmission rate of 9.6Gbps, better addressing the increasing number of device connections and data transmission demands in smart home and smart office scenarios, providing a more stable and faster network connection experience.

2、Transmission Distance

　　The transmission distance refers to the effective range within which the WiFi module can stably transmit signals in an ideal environment with few or no obstacles. Many factors affect the transmission distance of WiFi modules, including transmission power, antenna gain, operating frequency band, and environmental obstacles.

　　Generally speaking, in a home environment, an ordinary WiFi router (which has a representative transmission distance for its WiFi module) can transmit signals at a distance of about 30-50 meters in an open environment for the 2.4GHz frequency band, while the transmission distance for the 5GHz frequency band is relatively shorter, typically in the range of 10-30 meters. This is because the 2.4GHz frequency band has a longer wavelength, allowing it to better penetrate walls, doors, and other obstacles, but its transmission rate is relatively lower; while the 5GHz frequency band has a shorter wavelength, which, although it allows for higher transmission rates, has weaker wall penetration capability, leading to significant attenuation when encountering obstacles, resulting in a relatively shorter transmission distance.

　　In office environments, where spaces are relatively open and there are fewer obstacles, the transmission distance of WiFi modules can be relatively farther. For small offices, a well-performing WiFi module can achieve a transmission distance of 50-100 meters in the 2.4GHz frequency band, covering the entire office area; while in large factories and warehouses, if high-gain antennas and high-power WiFi modules are used, the transmission distance can even reach hundreds of meters, meeting the needs for remote data collection and monitoring device connections.

　　However, in actual applications, due to the structure of buildings, the material of walls, surrounding electromagnetic interference, and other factors, the actual transmission distance of WiFi modules is often lower than theoretical values. For example, in buildings with reinforced concrete structures, the signal attenuation is more severe than in wooden structure houses; and in environments with a lot of electronic devices, such as near electronic factories and communication base stations, electromagnetic interference can significantly impact WiFi signals, leading to reduced transmission distances and signal quality. Therefore, when selecting WiFi modules, it is essential to fully consider the actual usage environment, choose modules with suitable transmission distances, and combine them with repeaters, amplifiers, and other devices to extend the signal coverage, ensuring that devices can maintain stable network connections throughout the usage area.

3、Transmission Power

　　Transmission power refers to the strength of the signal emitted by the WiFi module, usually expressed in milliwatts (mW) or decibel-milliwatts (dBm). The greater the transmission power, the farther the signal can propagate and the wider the coverage, but it will also consume more power and may cause greater interference to other wireless devices.

　　According to relevant regulations and standards, different countries and regions have strict limits on the transmission power of WiFi modules to ensure orderly wireless communication and avoid excessive electromagnetic radiation. For example, in China, the transmission power of 2.4GHz frequency band WiFi modules generally cannot exceed 100mW (20dBm), while the transmission power limit for the 5GHz frequency band is relatively relaxed, but it still has corresponding specified values.

　　In practical applications, for some small smart home devices, such as smart bulbs and smart sockets, due to their usage scenarios typically being indoors and close to the wireless router, there is no need for high transmission power, and generally, a 10-20mW (10dBm-13dBm) WiFi module can meet normal communication needs while also reducing power consumption and interference with other devices. However, for devices that need to transmit signals over a larger range, such as outdoor wireless monitoring cameras and industrial-grade wireless sensors, it may be necessary to select WiFi modules with transmission power close to the regulatory limits to ensure stable signal transmission over longer distances, but care must be taken to comply with relevant regulatory requirements to avoid potential risks from non-compliance.

4、Receiving Sensitivity

　　Receiving sensitivity refers to the ability of the WiFi module to detect and correctly receive weak signals, reflecting the module’s sensitivity to signals. Receiving sensitivity is usually expressed in negative dBm values; the smaller the value, the higher the module’s receiving sensitivity, allowing it to receive weaker signals and maintain a stable connection in farther distances or poorer signal environments.

　　For example, a WiFi module with a receiving sensitivity of -90dBm can operate normally in weaker signal conditions compared to a module with a receiving sensitivity of -80dBm, resulting in a correspondingly larger wireless coverage area. In practical applications, in scenarios where signals are easily obstructed or interfered with, such as corners of multi-story buildings or basements, choosing a WiFi module with high receiving sensitivity is particularly important. Even if the WiFi signal experiences significant attenuation during transmission, a module with high receiving sensitivity can still effectively capture the signal, ensuring stable device and network connections, reducing disconnections, and improving user experience.

5、Power Consumption

　　Power consumption refers to the amount of energy consumed by the WiFi module during operation, which is a key selection indicator for mobile devices powered by batteries or applications with strict energy consumption requirements. Low-power designed WiFi modules can significantly extend the battery life of devices, reducing usage costs and maintenance frequency.

　　Different types of WiFi modules have significant differences in power consumption. Some traditional high-performance WiFi modules may consume several hundred milliwatts or even more when operating at full load; while some WiFi modules designed for low-power applications, such as those used in smart wearable devices and IoT sensor nodes, can achieve standby power consumption as low as a few microwatts or even lower, with power consumption during data transmission controlled within several tens of milliwatts.

　　For example, in devices like smart wristbands, due to their small size and limited battery capacity, it is common to use extremely low-power WiFi modules to ensure that battery power does not deplete quickly due to frequent WiFi connections and data transmissions during prolonged wear. These low-power WiFi modules automatically enter low-power standby mode when there is no data transmission, quickly wake up to complete data exchange when there is data to send or receive, and then return to standby mode, thereby minimizing overall power consumption.

6、Interface

　　The interface types of WiFi modules are diverse, commonly including UART (Universal Asynchronous Receiver-Transmitter), SPI (Serial Peripheral Interface), and SDIO (Secure Digital Input Output), etc. Different interfaces have different characteristics and applicable scenarios, mainly used to connect the main control chip or other external devices to achieve data transmission and control command interaction.

　　The UART interface is a simple, universal serial communication interface, which has advantages such as ease of use, simple programming, and low cost, widely used in various microcontroller systems and connections with WiFi modules. Through the UART interface, the main control chip can easily send AT commands (Attention Commands) to the WiFi module to control various functions of the WiFi module, such as connecting to wireless networks, sending, and receiving data, etc. Many low-cost smart home devices, such as smart temperature and humidity sensors and smart curtain controllers, often choose WiFi modules with UART interfaces to reduce development difficulty and costs while meeting basic network connection and data transmission needs.

　　The SPI interface is a high-speed synchronous serial communication interface that can achieve high-speed data transmission, suitable for application scenarios requiring high data transmission rates. Compared to the UART interface, the SPI interface requires more pin resources for data transmission but has higher transmission efficiency. In some industrial automation devices and smart medical devices where real-time performance is crucial, if the main control chip has SPI interface resources and requires the WiFi module to quickly and stably transmit large amounts of data, such as real-time status monitoring data in industrial control and physiological parameter data in medical devices, then WiFi modules with SPI interfaces will be a good choice.

　　The SDIO interface was originally a standard for connecting SD storage cards but is also widely used for connecting high-performance WiFi modules with main control chips. The SDIO interface has a high data transmission bandwidth, capable of meeting the demands for high-speed data transmission scenarios such as HD video streaming and large file transfers. For example, in smart devices with multimedia functions, such as smart TVs and tablets, when the WiFi module needs to achieve smooth online video playback and fast local file sharing, using WiFi modules with SDIO interfaces can better leverage their high-speed data transmission advantages, enhancing user experience.