Multipath Fading in IoT: What It Is and How to Fix It

Internet of Things products have become widely used in homes and businesses, and most people expect them to work nearly seamlessly, with little or no delay in responsiveness. 

Although many IoT devices function with low latency, that could change due to an issue called multipath fading.

What Is Multipath Fading?

Multipath fading occurs due to the dynamic nature of a signal traveling through space. Instead of directly going to the target via a single path, there are multiple routes it could take, and the travel time associated with each varies.

Although the speed of signal propagation remains constant, the paths are different lengths, meaning the time required for the signal to reach its target varies. Complications can also arise if the signal hits various things—such as trees and buildings—while moving.

Since the time required for a signal to reach an IoT device varies depending on its path, this phenomenon can cause decreased signal quality or interference, and both may worsen the product’s reliability and functionality. Additionally, multipath fading creates weak signal spots.

How to Address Multipath Fading in Development

However, developers can make various decisions to mitigate these problems.

Design for the Intended Use Case

Market analysts suggest the IoT market will grow at a compound annual rate of 11.4 percent from 2024 to 2030. Additionally, those purchasing the devices use them in applications ranging from healthcare monitoring to predictive maintenance.

IoT developers must remain aware of what their target audience will do with the products after purchasing them. They can then use those insights to steer design decisions. 

For example, multipath fading and signal interference would likely be more of an issue in environments with numerous IoT devices or those relied upon in outdoor areas with many buildings and trees. 

In contrast, multipath fading will be less problematic if someone primarily uses the device indoors with few other signal-creating products nearby.

When updating an older connected device model, developers should listen to user feedback about issues likely caused by multipath fading. They can then get a clearer idea of the extent of the matter and confirm if previous mitigation methods have not worked as well as expected.

Developers should also consider the likelihood of multipath fading causing decreased data accuracy. For example, the retail industry enjoyed more than $7 trillion in 2023 sales. 

Many forward-thinking executives install IoT sensors to tell how many people are in particular store areas and how the numbers change according to the time of day. 

Alternatively, they may use connected devices to determine engagement levels with interactive displays. However, if multipath fading causes users to get delayed readings, the data could be less valuable than anticipated.

Use Modeling Tools

IoT developers should also make advanced modeling tools part of their workflows. These resources can show users the probable effects of making particular design changes to reduce multipath fading. 

Antenna diversity is a common way to minimize the issue, and it involves using multiple antennas at the transmitter and receivers. Multiple-input multiple-output (MIMO) communication products utilize those components to lessen noise and interference while enhancing performance.

Sellers often group MIMO communication products according to their number of antennas. However, people purchasing IoT devices may initially feel less concerned about that aspect, especially when unfamiliar with multipath fading and its effects. 

Fortunately, developers can rely on modeling tools to clarify important questions, such as how the location and number of antennas on a connected device could improve or degrade its performance.

Besides using design tools for the devices, developers should strongly consider options that let them track activity on a network level. 

For example, some professionals in the electronics industry propose preparing for the 6G network with a digital twin that gets updated with signals from IoT devices.

Developers may use various digital twins as they progress with designs. While a radio-frequency-specific one shows transceiver and antenna behaviors and signal propagation, a network digital twin allows studying the end-to-end signal path to see which factors disrupt it.

Select the Appropriate Hardware 

IoT developers should also choose hardware that can adapt to changing conditions, raising the likelihood of their products sending and receiving consistently strong signals. 

One possibility is to use adaptive power components that alter the transmission power based on the strength of the received signal. Such changes can reduce the severity of multipath fading.

Similarly, adaptive equalization algorithms could make continuous adjustments during changing channel conditions. Since such variations can occur rapidly, swift alterations in the background can cause smoother user experiences.

In one real-life example, researchers created an adaptive antenna for IoT devices that gathers real-time information about the device’s location. This component automatically tracks the target’s movements, making input frequency adjustments as necessary. 

The group concluded that this approach optimizes spectrum utilization and minimizes interference. Additionally, they hope to automate future versions of this antenna, making it particularly suitable for demanding IoT applications such as self-driving cars or media streaming services.

Pursue Continuous Improvement

Besides applying these tips to manage multipath fading, IoT developers should remain aware of emerging technologies and techniques they could try. Attending conferences and other professional gatherings to hear about what others have attempted is an excellent way to grow.

Multipath fading will remain an obstacle. However, since IoT devices are only becoming more popular, developers must look for creative and effective ways to overcome this problem Succeeding could have long-term effects on how people perceive the quality and performance of connected products and those producing them.