Telecommunications networks use modulation techniques to transmit information wirelessly between mobile devices and cell towers. These modulation strategies have evolved over time to meet the increasing demand for faster and more reliable communication across different generations of cellular networks.
The first generation (1G) of wireless technology was introduced in the 1980s, and used analog frequency modulation for voice calls.
2G networks became commercially available in 1992 and used three common multiple access technologies for accommodating multiple simultaneous users:
•Frequency Division Multiple Access (FDMA)
•Division Multiple Access (TDMA)
•Code Division Multiple Access (CDMA)
Third and fourth generations of network technologies were introduced in 1998 (3G), 2006 (4G), and in 2011, 4G-Long Term Evolution (LTE).
All 3G systems utilize CDMA/WCDMA technology.
Reference: NTP Technical Report on the Toxicology and Carcinogenesis Studies in Sprague Dawley (Hsd:Sprague Dawley® SD®) Rats Exposed to Whole-body Radio Frequency Radiation at a Frequency (900 Mhz) and Modulations (GSM and CDMA) Used by Cell Phones: Technical Report 595 [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK561723/
Orthogonal Frequency Division Multiplexing (OFDM) is a widely used modulation scheme in 4G communication systems such as Long-Term Evolution (LTE) and LTE Advanced, and it has also become the standard modulation format for 5G New Radio. Quadrature Amplitude Modulation (QAM) is a modern digital modulation technique used in 4G, 5G and Wi-Fi6 networks.
Many new modulation and multiple access (MA) schemes are being developed for 5G to meet the changing demands of large-scale, heterogeneous traffic and users.
Energy efficiency improvements are imperative for 5G networks, and optimum modulation techniques can be employed to reach the capacity increase in 5G. Satellite communications also employ complex modulation schemes to improve spectral efficiency and minimize nonlinear amplification in the RF power amplifier. *References at the bottom of the post.
Pulse modulation involves transmitting a series of pulses to convey information. Some studies have suggested that this pulsing effect by radiofrequency radiation could have negative health effects on health by interfering with biological processes.
Does ICNIRP (The International Commission on Non-Ionizing Radiation Protection) consider modulation in its research and guidelines on non-ionizing radiation?
According to ICNIRP:
•Its guidelines account for all RF-EMF transmission protocols and modulation schemes, and so in terms of biological or health effects, these factors are not new. https://www.icnirp.org/cms/upload/publications/ICNIRPNoteMay2021.pdf
•ICNIRP considers the potential for different types of radiofrequency EMF exposure to adversely affect health, including sinusoidal (e.g., continuous wave) and non-sinusoidal (e.g., pulsed) EMFs, and both acute and chronic exposures.
•ICNIRP considers all potential adverse health effects (including non-thermal effects) and sets restrictions to ensure that none occur, regardless of the mechanism of interaction between the exposure and the body. The lowest exposure levels that can cause adverse health effects are due to thermal mechanisms, and so restrictions have been set based on the thermal effects, as these will protect against any other effects that could occur at higher exposure levels.
Quote: “The observation of effects does not necessarily mean the finding of a hazard” Allan H. Frey
(Allan H. Frey was the first American to publish on the microwave auditory effect (MAE). Frey’s “Human auditory system response to modulated electromagnetic energy” appeared in the Journal of Applied Physiology in 1961).
IEEE Transactions on Microwave Theory and Technique Feb. 1971:
It was found that carrier frequency, and the relationship of the modulation to the function in its phases are critical in the effect of low power density rf energy on some functions of higher organisms (Frey, 1962, 1963, 19671 Frey and Siefert, 1968).
For example, perception in the auditory system can be induced with carrier frequencies that penetrate the head but not those that do not penetrate the head, e.g. at 1 GHs but not at 10 GH.
The auditory system perception cannot be produced unless the carrier is modulated.
The brainstem responses have not been observed with an unmodulated carrier.
The isolated frog heart cannot be driven to arrhythmia if the rf pulse Impinges upon the heart at the P wave but it can be so driven if the rf pulse Impinges at the occurrence of the R wave.
It was found that there are critical body areas (Frey, 1967).
Peak rather than average power density was determined to be the more Important variable in the study of the effect of modulated low power density rf energy on biological functions (Frey, 1962, 1967).
Reference: In Press. IEEE Transactions on Microwave Theory and Technique Feb. 1971. (Special issue on Biological Effects of Microwaves) https://apps.dtic.mil/sti/pdfs/AD0716044.pdf
2004: Biological Effects of Radiofrequency Fields: Does Modulation Matter?
Modulation has been a factor in public controversy related to health concerns. Following recommendations of the International EMF Project of the World Health Organization (WHO), a host of recent studies have examined possible biological effects of modulated RF energy similar to that produced by major wireless access technologies (such as GSM, TDMA, CDMA, TETRA), with separate evaluation of effects of each technology.
Coherent Oscillations of Biological Structures In the 1970s and 1980s the noted physicist Fröhlich (now deceased) proposed that RF fields can excite ‘‘coherent oscillations’’ in cell membranes and macromolecules (8). Hyland (9) has cited this work in support of his claims that biological systems can be influenced by the modulation characteristics of microwave signals from mobile phones. However, Adair (10) showed that the damping effects of water surrounding biological structures are far too strong to allow resonances to exist at RFs. Moreover, the energy that can be added to a biological structure by an RF field of reasonable strength is many orders of magnitude below the energy already present in the structure due to random thermal agitation. Supporters of the theory have not rebutted Adair’s objections, and other theories (e.g. 11) that propose sharp frequency effects in biological systems fail for similar reasons.
At least one expert group in the West has issued ‘‘precautionary’’ recommendations related to modulation. In May 2000, the Independent Expert Group on Mobile Phones (IEGMP) advised that ‘‘as a precautionary measure, amplitude modulation around 16 Hz should be avoided if possible, in future developments in signal coding’’ (15). This recommendation was also based on studies related to the calcium efflux effect.
Large body of studies from countries of the former Soviet Union reporting modulation-dependent effects, which have not been reviewed extensively by Western agencies. Notable among these are studies by the group led by Akoev in Pushchino (Russia) that reported modulation-dependent effects in a variety of in vivo and in vitro systems (19–24).
One thing is clear: If modulation is biologically significant (apart from a few special cases such as intense pulses), the entire rationale for RF exposure guidelines would need revision. Present evidence does not indicate that this is the case. While more data will be published that bear on this issue, they will not be coming in quickly and they are unlikely to be definitive. Given public concerns about the safety of wireless communications systems, the issue of ‘‘modulation’’ will not be easily settled.
Reference: Kenneth R. Foster and Michael H. Repacholi “Biological Effects of Radiofrequency Fields: Does Modulation Matter?,” Radiation Research 162(2), 219-225, (1 August 2004). https://doi.org/10.1667/RR3191
The effect of modulation Dr. Andrew Goldsworthy, Lecturer and Biological Safety Officer (retired) Imperial College London.
Living cell membranes are electrically non-linear and have a voltage across them of approximately 70mV. They are pierced by countless ion channels that behave like electrically biased Schottky diodes capable of rectifying and so demodulating any alternating signal (including microwave frequencies) with the demodulated low frequency components appearing between the inside and outside of the cell. This is what does most of the damage and here is why:
The cell membrane is mainly made of a lipid bilayer only about 10nM thick, with proteins such as ion channels “floating” in it. The membrane itself is negatively charged because it has outwardly directed negatively charged phosphate groups and is normally stabilised by divalent positive calcium and magnesium ions that cross-link them. But the demodulated cell-phone signal makes the negative membrane and its protective divalent ions move in opposite directions. This destabilizes the membrane and makes it more likely to perforate and collapse the voltage gradient across it. This, in turn, opens voltage-gated calcium ion channels in the membrane that let huge numbers of calcium ions into the cell down a massive 10,000:1 electrochemical gradient.
In nature, this increase in the internal calcium concentration is taken as an indicator to the cell that its membrane (and by implication, the whole cell) has been damaged and sets in train a series of repair mechanisms, which uses a great deal of metabolic energy. If it succeeds, the cell is repaired, if not, the cell dies, but either way a great deal of energy is used. This may in large part explain the chronic fatigue syndrome that was found in early mobile phone users (Yuppie flu) and is now much more widespread in the community due to our constant exposure to cordless phones, their base stations, WiFi and all the other wireless devices that current ICNIRP guidelines regard as safe.
Quote: “Many experiments do not include pulsing and modulation of the carrier signal.” Kostoff et al., 2020
Citation: Ronald N. Kostoff, Paul Heroux, Michael Aschner, Aristides Tsatsakis, Adverse health effects of 5G mobile networking technology under real-life conditions, Toxicology Letters, Volume 323, 2020, Pages 35-40, ISSN 0378-4274,https://doi.org/10.1016/j.toxlet.2020.01.020.
There are concerns among some researchers and activists that the emergence of Brillouin precursors, which are sharp transients caused by the dispersion of broadband electromagnetic pulses in a dielectric, could have potential health impacts in the context of 5G technology. Some studies suggest that these precursors may increase the strength of electromagnetic radiation pulses and cause them to penetrate deeper into the human body than previously thought, potentially leading to health effects such as tissue damage and cancer. However, there is debate among experts over the validity of these concerns, with some arguing that the evidence is inconclusive or that the precursors may not pose a significant risk at the levels at which they are produced in 5G networks.
Are pulsing EMFs more bioactive than CW (continuous wave) EMFs?
•Comparing DNA damage induced by mobile telephony and other types of man-made electromagnetic fields Panagopoulos, 2019
It is important to note that except for the RF/microwave carrier frequency, Extremely Low Frequencies – ELFs (0–3000 Hz) are always present in all telecommunication EMFs in the form of pulsing and modulation.
The “ion forced-oscillation mechanism” for irregular gating of electro-sensitive ion channels on cell membranes which predicts that pulsing EMFs are more bioactive than CW EMFs of the same other parameters, and that the biological activity of any specific type of EMF is inversely proportional to its frequency and proportional to its intensity [, , 
•Human‑made electromagnetic fields: Ion forced‑oscillation and voltage‑gated ion channel dysfunction, oxidative stress and DNA damage (Review)
Panagopoulos et al., 2021
The ELF/ULF EMFs and even more the pulsing RF EMFs with ELF pulsations such as all WC EMFs, are predicted to be the most bioactive.
It has been claimed that the ELF components of complex RF-ELF EMFs of WC need to be ‘demodulated’ in order to be sensed by living organisms (232). ‘Demodulated’ or not, the fact is that the ELF components of modulated/pulsed WC signals can be directly sensed by both ELF meters/spectrum analyzers and living organisms (40,55).
Both DNA damage and alterations in protein synthesis, especially increased levels of stress proteins, are reported to be induced similarly by both ELF and pulsing RF EMFs (237,238). However, the effects of pulsing RF were attributed to the carrier frequency, and it was not considered that perhaps in both cases (ELF and pulsing RF) the ELF components might be responsible for the effects, as suggested now by the present study.
The Europaem 2016 Table 3 suggests that the recommended radiation maximum levels of Wi-Fi are 1000 times less than for FM. Wi-Fi is pulsed, FM not.
As per ‘Biological Effects of Radiofrequency Fields: Does Modulation Matter?’ from 2004 (referenced earlier on in the post), given public concerns about the safety of wireless communications systems, the issue of ‘modulation’ will not easily be settled, even in 2023