The world is sitting on the edge, awaiting the rollout of 5G. While the excitement is palpable and there is immense curiosity on how 5G will pan out and transform our lives, there are also concerns about the plausible adverse effects of this fifth-generation technology. Before we get to the impact of 5G on our health, I would like to first discuss the technology itself - how it works and the regulation surrounding its implementation.
We dread the word ‘radiation’ but forget that we are bathing in radiation all day long from cosmic rays of the sun and other stars, thermal and electromagnetic radiation from computers, hand-held devices, Wi-Fi hot spots and wireless cell towers etc. The impact of radiation on a living organism depends on the amount of radiated energy that gets absorbed in the body. If you read the manual of any mobile phone, you will find the value of specific absorption rate - SAR, mentioned therein. Regulators approve the device only when it meets the safe SAR limit as dictated by authorities. Keeping the health aspect in mind, the regulators approve an upper limit of radiation for any technology based on long-term study and 5G is no exception.
The mmWave Conundrum
First, let us understand why we need mmWaves for 5G. When you look at the 5G requirements, we are looking at extreme mobile broadband connection, ultra-reliable low latency connection and massive connection density. The question is, how do you achieve these performance requirements? For high throughput, channels with wideband spectrum are needed. If it is sub 6GHz, even if the entire spectrum is allocated, the bandwidth that can be allocated is limited to 6GHz. You cannot do anything more than that. If a large number of applications require high bandwidth usage, the wireless base stations need to provide a very high system throughput as 6GHz becomes the limiting factor, even when the entire 6GHz is made available. The spectrum at sub-6GHz is split into many different bands and the allocated spectrum for cellular wireless communication is currently limited to a channel bandwidth of 5, 10, 15 or 20 MHz. In order to meet the 5G eMBB (Enhanced Mobile Broadband) requirements, the channel bandwidth needs to scale beyond 100MHz - up to at least 1 GHz. In order to allocate a channel bandwidth of 100MHz or higher, mmWave bands that have a larger channel bandwidth are considered. 5G New Radio (NR) supports beam steering and narrow beam formation that could be directed and transmitted toward a specific user when there is a need to transmit. 5G requirements demand 100 times energy efficiency and the way to meet this requirement is to transmit only when and where it is required.
In the current system, the base station may have multiple sectorial antennas and all of them are used to transmit in all directions at all times to provide required coverage and capacity. However, in 5G New Radio, the UE (User Equipment) can be localized and the base station can transmit to the UE in a directed beam when there is a data demand. The Massive MIMO technology allows radiation of the transmitted power only when the user consumes data. The control signaling detects the state of the UE, the density of the connection requirements and decides the right number of transmission sources that need to be activated for communication. This technique of transmitting signals only when it is required and to those users who need it, significantly reduces the amount of radiation.
5G Spectrum Bands
Let us look at 5G radio spectrum band specifications. 5G operates in two distinct bands - Frequency Range 1 or FR1 and Frequency Range 2 or FR2. FR1 operates between 0Hz to less than 6 GHz, and FR2 operates at frequencies above 24 GHz band. mmWave falls under FR2 band and currently a lot of trials and auction are taking place around 28 GHz band. The concern that has been raised pertains to mmWaves. Let us first demystify the basic attributes of a radio technology. When it comes to the characteristic of a wireless network, usually three parameters get discussed most of the time viz. connection speed, latency and connection density. For example, a 4G network provides a radio technology that is superior to the 3G radio technology. However, what is less discussed is the total energy consumed by a generation of radio technology. 5G radio specification in IMT-2020 demands 100 times energy efficiency as compared to 4G technology. If a radio specification is to be accepted by ITU as a 5G technology standard, the candidate technology has to comply with this requirement, which means that the overall energy consumption has to reduce by 100 times. As the frequency of an electromagnetic wave increases, its wavelength reduces. When we are comparing 6 GHz versus 28 GHz, there is a significant reduction in the wavelength from centimeter range to millimeter range wavelengths. As the wavelength reduces, the scattering and penetration loss increases. Let us compare a balloon with a needle and the kind of impact each of these will have when they hit a body. If a balloon hits you, the balloon will bounce back without getting inside your body but if a needle hits, it will pierce through the body. A similar phenomenon happens in an electromagnetic wave. When the wavelength is shorter, the signal gets attenuated faster as the amount of energy that gets absorbed in the media is higher as compared to the waves with longer wavelength. When a shorter wavelength signal passes through the body, the body absorbs more energy as compared to a longer wavelength signal. This is where the regulatory authorities come in to ensure a safe limit to the radiation power to avoid any harmful effects on the living beings. As a wireless communication technology is proposed to use an electromagnetic wave as a carrier wave, detailed studies are carried out before it gets approved. The level of permitted energy is kept significantly below the safe limits to avoid any harm to humans and other living beings.
Will 5G cause harm to living beings?
The 5G User Equipment and the cell towers are both sources of radiation that transmit electromagnetic energy. As discussed above, there is a compliance requirement on the upper limit of the SAR value or the specific absorption rate. As long as the SAR value is within the regulatory limit, we can assume that it is safe and fit for use. When it is beyond the threshold that has been defined as the regulatory limit, it can cause harm. However, no devices can operate if they violate the limit.
Multiple clinical trials have been conducted not just for 5G but also for earlier generation technologies like 2G/3G/4G when they were rolled out. The studies were mainly on electromagnetic radiation and their impact on health. There was a lot of skepticism when the first cellular technology roll out was being planned. However, these wireless networks have been in use for close to two decades now and there is no conclusive evidence of harm to humans due to these radiations.
Now, let us look at what has changed in 5G as compared to 4G. 4G uses frequencies typically below 3.6GHz bands for licensed spectrum. 5G uses both sub-6GHz and mmWave frequencies above 24GHz. mmWave wavelengths are shorter, incur higher loss and have higher absorption in the body as explained earlier. That is the primary reason why concerns over a potential health hazard have been raised, many of which are unfounded. 5G is 100 times more energy efficient than 4G. Majority of the energy consumption in a network comes from radio and this means, the transmitted power is expected to reduce by 100 times as compared to 4G. This has been enabled by a set of new technologies like dynamic beam steering, narrow beam width, cognitive transmission toward the user etc. that has been briefly discussed earlier. In simple terms, 5G new radio will transmit a narrow beam toward users rather than transmitting it in all directions. This will make a huge difference as 4G usually transmits in all directions all the time while 5G transmits only in the direction of an active user. Of course, there is a small amount of energy used all the time to detect the presence of any user but that has no significant effect.
For the blanket coverage, sub-6GHz spectrum is suitable and is the preferred spectrum for mass rollout. Most of the mobility issues will be done at sub 6GHz which is FR1. Any concern about mmWaves being bombarded at every place with the proliferation of cell towers is unjustified as it is not a commercially viable option per the current technology maturity. If everything has to be replaced by new radio operating at mmWave, it cannot be rolled out economically without a very compelling use case that can be monetized.
The 5G technology is here to stay and one can safely say that regulators are ensuring that it does not impact our health adversely.