Understanding | How Safe is WiFi? A Review of WiFi Issues

A piece of information regarding the dangers of WiFi

　　About WiFi radiation

　　WiFi has now become an integral part of our lives, and its radiation issues have been frequently questioned. There was once a news report about a pregnant woman’s family going door-to-door asking neighbors to turn off their WiFi to avoid affecting the fetus, which caused panic among many pregnant women. Another widely circulated claim is that “plants near wireless routers do not sprout.”

　　In reality, the impact of WiFi radiation on human health and safety is negligible. Currently, there is no scientific experiment or factual data that can prove electromagnetic waves have adverse effects on biological organisms. The effects that can be produced on biological tissues are mainly due to heating effects, which require a strong and focused electromagnetic field.

　　In addition to the level of radiation, information security is also a hot topic of concern. Today, I recommend an article titled “A Review of WiFi Issues”.

　　A Review of WiFi Issues

　　Written by Zheng Jiaqiang (Professor at Nanjing Forestry University, School of Mechanical and Electronic Engineering)

　　”Boss, what’s the password?” The boss or waiter knowingly recites a string of numbers, a phone number, or some meaningful combination of digits, and then the heads bow down… This is a scene you often see or hear in tea houses, restaurants, coffee shops, car dealerships, and shops in recent years, or perhaps you do this often yourself.

1. What is WiFi?

　　With the rapid development of mobile internet, wireless routers have entered thousands of households (currently a dual-band router costs around 200 yuan), and humanity’s dependence on and demand for WiFi is increasing day by day. WiFi (Wireless Fidelity) was originally an abbreviation for wireless fidelity, and in wireless local area networks (WLAN), it refers to “wireless compatibility certification”. Essentially, it is a commercial certification and a wireless networking technology, also known as the 802.11b standard, which is an industrial standard for wireless network communication defined by IEEE. Due to its fast speed, high reliability, and low networking costs, WiFi technology has an absolute advantage in meeting users’ high-speed data transmission needs within specific areas.

　　An Access Point (AP) is also known as a wireless bridge or wireless gateway, which continuously receives and transmits data in a wireless local area network. Any PC equipped with a wireless network card can share resources from a wired local area network or even a wide area network through an AP. Theoretically, adding a wireless AP to the network can exponentially expand the network coverage diameter and allow more network devices to be accommodated. Each wireless AP typically has an Ethernet interface for connecting wireless and wired networks.

2. Who pays for public area WiFi coverage?

　　With the rapid proliferation of smartphones and the integration of mobile e-commerce with online and offline, the public’s demand for free WiFi coverage in public areas is increasing. However, there is no such thing as a free lunch; who builds the WiFi? Who pays? How is it built? Therefore, the sustainable development of WiFi construction and commercial operation models is particularly important. According to various networks, the main WiFi operation models in China include box models, carriage models, port models, and business district models, and I will add a public welfare model here.

　　(1) Box model. This is where WiFi operators utilize the existing broadband of small and medium-sized businesses (mainly catering and entertainment businesses) by providing advertising routers (or set-top boxes) with a promotional portal page for free or for a fee, replacing the businesses’ original routers, thus integrating and operating the scattered WiFi resources in the city. For example, the Alipay free WiFi plan. In the box model, WiFi operators mainly earn revenue from advertisements and payments, while businesses can benefit from various O2O applications such as information push, ordering, and payment provided by the advertising routers (or set-top boxes) from WiFi operators, but they need to pay for the broadband costs themselves. The advantage of the box model is low construction costs, while the disadvantages are scattered businesses, slow scale formation, low entry barriers, and intense industry competition. Once covered by large commercial WiFi, they will lose their survival space.

　　(2) Carriage model. This is where WiFi operators convert the signals from basic telecom operator base stations into WiFi signals (LTE-Fi) within vehicles, achieving “mobile coverage” for buses, subways, high-speed trains, and other transportation tools. For example, 16WiFi, its advantages are low investment, a large audience, and high user usage rates, which can leverage this advantage to obtain stable advertising revenue. However, the carriage model currently faces technical issues, such as the stability of the converted WiFi signal, internet speed, and disconnection issues.

　　(3) Port model. This is where WiFi operators implement WiFi coverage and commercial use in public places such as airports and train stations. For example, Airport Free Wi-Fi, which uses dedicated lines and professional APs to cover ticket halls, waiting halls, and squares. The advantage of the port model is that it can form a nationwide WiFi network based on city entry and exit ports, but the downside is that the covered audience comes from all over the country, mostly transient visitors, making it difficult to achieve localized applications and local commercial support. Therefore, this model mainly operates WiFi comprehensive portal applications (news, mobile games, videos, etc.).

　　(4) Business district model. This is where WiFi operators collaborate with urban information infrastructure builders (basic telecom operators) based on a certain business model to achieve city-level WiFi coverage and commercial use in large commercial entities within business districts through fiber optic dedicated access and business district-level AP hotspot construction, providing integrated online and offline operation platform services for shopping centers, department stores, supermarkets, brand stores, restaurants, leisure, and entertainment businesses in major business districts. Through mobile smart business district APP mobile clients (remote) and WiFi (near-field) clients, it provides information interaction and online-offline integrated transaction matching based on location services (LBS) for users and businesses. For example, adding a functional plugin to the WeChat public platform, “WeChat Connect WiFi,” can provide merchants’ offline locations with a complete and convenient WiFi connection solution, while through the WeChat ecosystem and open platform system, merchants can better reach offline users and can use WiFi near-field service capabilities to bridge online and offline, improving merchants’ operational efficiency.

　　(5) Public welfare model. This is a public welfare model where operators build, and the government appropriately subsidizes maintenance and traffic costs. Operators focus on statistical sampling, big data mining, and innovative business models to offset construction investment and operational costs, exploring the profit model of the WiFi 2.0 commercial era. The public welfare model is mainly based on market failure and convenience for the public, guiding other builders not to construct WiFi coverage in already covered public areas; to ensure the effectiveness of WiFi usage in covered areas, network optimization is conducted according to standards; and for areas with repeated construction and co-frequency interference, a dual-frequency WiFi signal method is implemented to increase signal strength and solve interference issues. This free WiFi network can serve as an important information platform for city services to citizens, gradually integrating relevant public information resources from various departments, achieving the effect of benefiting the public.

3. Is WiFi safe?

　　(1) Demonization of WiFi radiation phenomenon. According to Yangzi Evening News, there was once a news report that attracted a lot of attention: a pregnant woman’s family went door-to-door asking neighbors to turn off their WiFi to avoid affecting the fetus, which caused panic among many pregnant women. Another widely circulated claim is that “plants near wireless routers do not sprout.” In reality, the most common wireless routers operate at power levels ranging from tens to hundreds of milliwatts, which is less than the power of an ordinary mobile phone (the maximum radiation power of a mobile phone is 2 watts). Since the intensity of radiation decreases with the square of the distance, compared to mobile phones, WiFi devices like routers are much farther away from users, resulting in a much lower power density of radiation exposure. The electromagnetic wave bands used for WiFi internet access generally range from 2.4GHz to 5GHz, which is quite close to the radio frequency electromagnetic wave bands used by mobile phones. The UK Health Protection Agency once estimated that even if a wireless router is left on for a year at a distance from the body, the radiation produced is equivalent to that of using a mobile phone for just a few minutes. The impact of WiFi radiation on human health and safety is negligible. Currently, there is no scientific experiment or factual data that can prove electromagnetic waves have adverse effects on biological organisms. The effects that can be produced on biological tissues are mainly due to heating effects, which require a strong and focused electromagnetic field. The electromagnetic waves used by WiFi are non-ionizing radiation, and under full load, the tested electromagnetic radiation is 24-31 microwatts per square centimeter, far below the current limit of 40 microwatts per square centimeter set by China’s “Electromagnetic Radiation Protection Regulations” (the EU standard is 450 microwatts per square centimeter, and the US is 600 microwatts per square centimeter). This is comparable to the radiation value of a mobile phone in standby mode, far below the radiation of a mobile phone during calls.

　　(2) WiFi has security risks in usage. The security level of WiFi devices is very high; the issue lies in how WiFi is used. Wireless networks with passwords are more secure than free WiFi, while wireless networks provided by operators require user login operations, which are more secure. However, it is undeniable that the security risks of WiFi usage are still significant. Due to the low technical threshold for commercial WiFi, anyone can set up a WiFi network by purchasing equipment, software, and network services, and it is technically very easy to set up a fake WiFi environment in public places to lure users into connecting. Hackers compromise user accounts and passwords by setting traps; they do not breach the security of WiFi devices but exploit vulnerabilities in insecure web browsers. Unsecured wireless networks are easier for hackers to compromise. It is reported that Tencent Security announced a partnership with domestic commercial WiFi service providers and some businesses to establish the “Tencent Security WiFi Alliance” to achieve WiFi network coverage. Based on Tencent’s security open platform, the security WiFi alliance connects resources from telecom operators, commercial WiFi operators, and businesses to provide free secure WiFi service networks; Tencent’s mobile manager builds a unified security WiFi service standard, allowing users to connect to secure WiFi networks simply through Tencent’s mobile manager. When using Tencent’s “全民WiFi” (Universal WiFi), users can automatically install drivers and create WiFi connections by simply plugging in and scanning, with features to prevent unauthorized access, block malicious websites, and intercept Trojan fraud.

4. The future of WiFi

　　(1) Drone-based WiFi signal transmitters. It is said that Facebook founder Mark Zuckerberg and Google are constantly competing for drone network services. A few years ago, he quietly acquired the British solar drone manufacturer Ascenta and hopes to develop a drone system that uses low-flying drones to maximize network signal strength, essentially turning drones into flying WiFi signal transmitters. These solar-powered drones can fly continuously in the air for months or even years, aiming to bring internet access to remote areas worldwide. It is reported that a team of surveillance drones serving in Iraq has been reassigned to provide WiFi in remote, poorly connected battlefields. The RQ-7 Shadow drone, which plays roles in surveillance and intelligence gathering among troops in Iraq, is now becoming the world’s most advanced wireless router, using drones as a hub to supplement radio signal limitations and increase data transmission channels. This project, organized by the US DARPA, has modified drones that can transmit 1GB of data per second (equivalent to 4G network transmission), allowing access to tactical centers and reference mission data in remote war zones. This information is internal and not carried on hand, but can now be viewed on computers. The challenge of the project lies in how to equip existing drones with wireless systems, as the Shadow is not the largest drone, making it difficult to add more equipment. However, DARPA claims to have developed a micro-antenna that can emit high-frequency directional millimeter waves, significantly enhancing signals through special amplifiers, allowing drones to provide signals at high altitudes without being seen by enemies. They use external devices to provide wireless services, which are only 8 inches wide and weigh only 20 pounds, capable of providing 9 hours of service. DARPA also claims to have developed a point-to-point connection method that can ignore the effects of terrain and obstructions while ensuring signal strength. Currently, the project is still in the design topology phase, but it is unclear what improvements can be made to allow the lightweight Shadow to withstand bad weather. The plan will integrate wireless devices into aircraft and ground vehicles, completing docking points for four WiFi drones and two ground vehicles.

　　(2) Passive WiFi technology. According to PC World on August 5, 2014, a team from the University of Washington developed WiFi devices that do not require power, utilizing WiFi backscatter technology to achieve a combination of wireless power and WiFi, allowing the use of surrounding radio wave signals as energy and establishing connections for data transmission with WiFi networks. Passive WiFi devices could be widely used in the Internet of Things, connecting a large number of devices to the internet. Traditional WiFi devices consume a lot of power, while WiFi backscatter technology will significantly reduce power requirements, even eliminating the need for power.

　　(3) LiFi technology combining light and WiFi. Light, like radio waves, is also an electromagnetic wave, and its frequency is 100,000 times that of WiFi hotspot frequencies. The combination of light and WiFi creates LiFi (Light Fidelity, visible light wireless communication, also known as optical fidelity technology), which operates on the principle of using rapid light pulses to wirelessly transmit information (by adding a microchip to an LED bulb, the bulb can become a wireless network transmitter). Information can be encoded in light at different rates, for example, LED on represents 1, off represents 0, and by rapidly switching on and off, information can be transmitted (different colors of LEDs can also be used to transmit data). This means that signals can be transmitted through rapidly flickering bulbs, with flicker rates fast enough to be imperceptible to the human eye, while light-sensitive sensors can receive these changes, allowing various mobile receiving ends to decode the data through visible light. Fudan University has already used light to replace radio waves for data transmission, achieving speeds 10 times faster than WiFi, demonstrating that four computers can connect through a single bulb, with offline maximum speeds reaching 3.25G and real-time system average internet speeds reaching 150M, making it the world’s fastest “light internet”. The spectrum is 10,000 times larger than the radio frequency spectrum, meaning LiFi has greater bandwidth and higher speeds, and network setup requires almost no new infrastructure. “Where there is light, there is network signal; turn off the light, and the network is gone.” However, LiFi technology still has limitations, such as not being able to penetrate walls. Although it is secure, if the light is obstructed, the network signal will be cut off. In practical applications, can you endure being under constant light exposure? Due to these limitations, LiFi can only serve as a supplementary method for wireless transmission in small spaces, such as providing WiFi through LiFi technology for underwater operations.

　　(4) High-altitude WiFi. Passengers on airplanes have always been required to turn off mobile devices, and after doing so, they rely on TVs and magazines to pass the time. However, WiFi connections on planes are becoming increasingly common. “In-flight WiFi” can be categorized into “local area networks” and “earth-to-sky connections”. Typically, airlines follow a three-step process: first, equip each seat with a tablet; second, establish an in-cabin local area network to achieve interconnectivity within the cabin; third, achieve earth-to-sky communication. From a technical perspective, there are mainly two ways to achieve earth-to-sky connections: one is through internal wireless networks installed on the aircraft and satellites for communication, and then through satellites to ground stations for communication, which then connects to domestic network operators for global coverage, but the biggest problem is slow speeds, only achieving “narrowband” transmission; the other method is to establish network links between onboard equipment and ground base stations, equipping the aircraft with dual modems and directional antennas, allowing the aircraft to communicate with these networks while flying overhead. However, this requires modifications to the base stations, and service is limited to routes where base stations have been modified. Additionally, when the aircraft is over the ocean or too far from ground base stations, speed and reliability will be affected.

　　(5) Global WiFi coverage. The idea of covering every corner of the world with wireless networks sounds like a beautiful vision, but an ambitious media development investment fund company in the US intends to make it a reality with a project called “Outernet”. This company is in contact with NASA, hoping to receive assistance in testing signal release in the International Space Station, and later needs NASA’s help to launch hundreds of mini-satellites (cubesats) into designated orbits. According to the plan, once the satellites reach their designated orbits, they will receive network data released from ground base stations, parse this data, and convert it into wireless network signals continuously released to Earth, providing WiFi services globally. The company expects to launch hundreds of mini-satellites into near-Earth orbit by June 2015, allowing any electronic terminal in any corner of the world to connect to and enjoy wireless networks. The future is uncertain.

　　（This article is reprinted from Zheng Jiaqiang’s Science Blog）