Most people leave Wi-Fi enabled on their iPhone or Android smartphone, so they connect to known Wi-Fi hotspots or access points quickly. Keeping Wi-Fi on also allows your mobile device to continually survey nearby access points’ names and identities. Is this safe, and how does Wi-Fi help location accuracy?
Location services on smartphones survey nearby Wi-Fi access points and report the name, identity, and signal strength to determine location. Several databases exist that lookup and return approximate coordinates. Combined with satellite, cellular, and other signals, Wi-Fi augments location accuracy.
Let’s go over the technology behind Wi-Fi positioning and how 4 other technologies in your smartphone are combining to produce a scarily accurate location. We also give you tips on how to protect yourself from Wi-Fi tracking.
The Main Strategy
While several positioning technologies are used to approximate your smartphone location, each technology is built around one primary method. GPS, cellular, Bluetooth, and Wi-Fi positioning all use triangulation to provide your smart device’s accurate location.
Triangulation is a mathematical process applying trigonometry and geometry to find location. Its purpose is to determine a singular unknown point by forming a series of triangles from an array of known points. This process is applied to cellular, Bluetooth, Wi-Fi, and global positioning systems via communication between each technology’s hardware.
For instance, Wi-Fi positioning uses various Wi-Fi access points located around your smartphone to triangulate your smartphone’s location within a few meters. Routers and range extenders are also used along with Wi-Fi access points to assist the triangulation process. However, this only works if the Wi-Fi on your smartphone is enabled.
Only Pros Know:
There is a fifth technology for positioning your smart device, ultrasonic cross-device tracking. This method of location tracking uses your microphone and requires a beacon device and a receiver device. The beacon device is any source of an audio signal within the range of your device. Your smartphone, in turn, acts as the receiver.
Your phone can receive audio information from beacon devices as long as the microphone and speaker are enabled. This form of location discovery requires no app or operating system permissions. It is often the source of eerily-specific targeted ads.
This video (6m25s@2x) describes how this new form of location tracking may further augment Wi-Fi location accuracy.
Back to Wi-Fi…
Wi-Fi Location Advantages
Each of these five location-finding technologies comes with its own merits and liabilities. Wi-Fi positioning possesses several advantages and disadvantages to determining one’s location. First, let’s take a look at the benefits associated with Wi-Fi triangulation.
One of the most apparent advantages of Wi-Fi positioning over every other location technology is its lower power usage.
GPS requires your smartphone to listen to very weak signals from the global satellite transmitters in space. It can take between 12 to 30 seconds to acquire a location. During this time, both Android and iOS mobile operating systems must prevent the hardware from sleeping. Compounding the problem is the process-heavy mapping software typically used while high-accuracy/fine-grain GPS location is used.
Cellular positioning also requires a relatively higher power consumption than Wi-Fi. The number of cellular towers and signal strength measurements makes it easier to determine location than satellite. But, when cellular signal is sparse or partially blocked like in buildings or around other radio signals, gaining a location fix is not only unreliable but can also consume battery power.
In contrast, Wi-Fi positioning systems require the least electrical requirement to function. Wi-Fi technology was specifically designed for nearby network communication.
With many smartphone devices supporting several Wi-Fi standards, there’s always an access point within range and broadcasting its identification. Smartphone operating systems need only collect the identifiers and signal strengths within range. A single internet request with this data set will return an approximate location with minimal battery drain.
Another advantage of Wi-Fi positioning is its passive nature. Although Wi-Fi positioning requires Wi-Fi access points to function, it does not require connection to these access points or Wi-Fi hotspots. Instead, Wi-Fi positioning works by listening for the broadcasting networks.
Your smartphone analyzes the identities and strength of each Wi-Fi signal in the vicinity. Then, the process will use that information to triangulate an approximate location for your device.
This process is relatively effective, capable of providing a 20-meter range of location accuracy using Wi-Fi access points and infrastructure with no calibration.
Wi-Fi has GPS and cellular location beat in another critical area: indoors.
Wi-Fi positioning is far more effective at providing a location approximation inside buildings.
GPS and cellular signals tend to bounce off structures, particularly in a condensed set of structures like cities. This can lead to a reasonably inaccurate location.
In contrast, Wi-Fi positioning can effectively produce location approximations within 5 meters in indoor settings with some calibration and fine-tuning.
Most buildings already have Wi-Fi access points installed, so it is far easier and more cost-effective to use these existing hardware. Additionally, Wi-Fi infrastructure is continuously growing, and with more access points will come more accurate location approximations.
Wi-Fi positioning is an effective tool for indoor coverage, mainly because it requires no additional hardware and will only improve in accuracy over time.
The preexisting infrastructure is Wi-Fi positioning’s clearest advantage.
In our internet age, Wi-Fi access points are prevalently available in locations around the world, particularly in densely populated cities.
Leveraging existing hardware infrastructure without additional cost gives Wi-Fi location an advantage that doesn’t hit the bottom line.
Companies are iterating on Wi-Fi assisted location to improve the functionality through software. Wi-Fi round-trip timing (RTT) uses time-of-flight rather than signal strength to calculate the distance between the device and access point.
This could enable even more accurate location approximations, roughly between 1 and 3 meters.
These are exciting additions to Wi-Fi location, but there are also downside disadvantages.
Wi-Fi Location Disadvantages
Causes of Inaccuracy
A common disadvantage experienced by users is for those who have recently purchased a new router or moved into a new home.
Wi-Fi positioning is not tied to your Wi-Fi connection. Instead, the routers and access points are mapped to the BSSID (Basic Service Set Identifiers) of your Wi-Fi network. Therefore, if you have recently moved or changed routers, your old router is likely interfering with your smart device’s Wi-Fi positioning accuracy.
A similar issue can also occur with accurately locating one’s IP address. This can be due to some ISP’s (Internet Service Providers) tendency to route their traffic to a central location before reaching the public internet. This can confuse the location of your IP address and the location of this central location.
Wi-Fi Tracking Prevention
Many people are concerned about the effectiveness of these location tracking methods, including Wi-Fi-based triangulation, viewing them as a privacy concern. If this is the case, you can take a few measures to prevent Wi-Fi positioning on your smart device.
- Turn off Wi-Fi when you are not using it. Use the app WiFi Automatic (F-Droid | Google Play) to automate this.
- Remove remembered Wi-Fi networks from your smartphone and computer that you no longer use.
- Do not register your home or work Wi-Fi router’s address.
- Randomize your MAC address.
- Use a wired adapter instead of Wi-Fi networks.
- Conceal your phone in a signal-blocking pouch or wrap it in aluminum foil, switching it to airplane mode when not in use.
It is important to note that there are plenty of other methods built into your smart device that enable location tracking. It would be difficult and inconvenient to disable each of these methods.
Ultimately, Wi-Fi positioning is among several effective methods enabling location tracking. Whether or not this technology is desirable or not for your circumstance is an effective way to augment and help location accuracy.
The Hated One YouTube channel has this excellent video (6m13s@2x) detailing all the ways your iPhone or Android smartphone tracks your location. It’s eye-opening and a bit concerning.