Radio Terms Unpacked

Substantial Written Evidence of Adequate Wireless Carrier Signal Strength (dBm) for three main Wireless Carriers for Telecommunications Service in Lenox, MA from Oct 28, 2022

Making Sense of RSSI, RSRP and RSRQ

Radio Signal Strength and Quality Terms Unpacked

  1. Reported in dBm, the Received Strength Signal Indicator (RSSI) is a measurement of electromagnetic power through the air, calculated from measured voltage over the entire bandwidth of occupied Resource Blocks (RBs); it is the total received power measured over all sub-carriers of the specified bandwidth including reference signals and the following from serving cell traffic:
    • co-channel serving cells
    • non-serving cells
    • adjacent channel interference
    • thermal noise
  2. Reported in dBm, the Reference Signal Received Power (RSRP) is a small fraction of RSSI; it is derived mathematically from the RSSI measurement, and represents electromagnetic power through the air of only the reference signals of a single Resource Element (RE) of an LTE Resource Block
  3. Reported in dB, the Reference Signal Received Quality (RSRQ) is calculated from RSSI and RSRP, following a formula adopted in a 3GPP specification



  • The measured voltage over the entire bandwidth is what matters; that is what is used to calculate RSSI for each specific wireless frequency band
  • RSSI has been the standard for measuring signal strength for all frequencies and for all generations of digital wireless signals
  • RSRP and RSRQ, introduced in the 36-series 3GPP specification are simply calculations based on the RSSI voltage measurement. RSRP considers only a small slice of RSSI and, therefore, both RSRP and RSRQ must be considered misleading and inappropriate for making any Wireless Telecommunications Facilities power regulation policy decisions.

A Bel is a fraction . . .

Every electrical term you’ve ever heard is named for a pioneer in the field of electricity. James Watt, Alessandro Volta, Heinrich Hertz, André-Marie Ampère, Georg Ohm and more are immortalized in measurements that bear their names. The Bel is named for Alexander Graham Bell, the man who (might or might not have) invented the telephone.

A Bel is a measure of “how much more.” If you have 1 Bel more of anything, you have ten times more. It doesn’t matter if it’s electricity, sound, or breakfast cereal. If you have one quarter today and tomorrow you have two and a half bucks, you have gained one Bel of quarters.

In order to make it easier to use Bel as a measurement, they are usually divided in 10. A deciBel (dB) is 1/10th of a Bel, and represents the steps between “what you have” and “10x of what you have.” It’s logarithmic and it is a relative, not absolute level.

Every time you add 10 decibels, you multiply by 10. DeciBel is handy for expressing large changes with easier to communicate numbers.

  • + 3 decibels is roughly twice as much,
  • + 6 decibels is roughly four times more
  • + 10 decibels — or one bel — is 10 times more (one zero)
  • + 20 decibels is 100 times more (two zeroes)
  • + 30 decibels is 1000 times more (three zeroes)

Amounts less than what you have are expressed in negative dB.

  • – 20 decibels is 100 times less (two zeroes)
    • – 30 decibels is 1000 times less (three zeroes)

      A signal from the cell tower is referred to as a “reference signal” and the power of that signal, as it’s received by your phone, is the Reference Signal Received Power (RSRP). It’s the critical measurement of cell tower reach.

      Cell phones operate at -115 dBm to -85 dBm (a difference of 30 dBm or 1,000 times). Said another way, an RSSI of -115 dBm is 1/1000th of the power of -85 dBm; Also RSSI of -55 dBm is 1,000 times more powerul than an RSSI of -85 dBm.

      dBm (decibel-milliWatts) is an abbreviation for the power ratio in decibels (dB) of the measured power referenced to one milliWatt (1 mW = 1/1,000 of a Watt). It is used in radio, microwave and fiber-optic communication networks as a convenient measure of absolute power because of its capability to express both very large and very small values in a short form. The following data is based on that published in the Cornet ED-85X Manual; the meter’s antenna is centered at 2,450 MHz and can meter RF Microwave Radiation from 700 MHz to 6,000 MHz.

      Note: see Case No. 18-1051, Mozilla v FCC to learn that, as of 2017, the FCC, by choice, classified broadband information services as Title 1 (unregulated), which means that there is no preemption of local authority for any Wireless services other than for telecommunications service which is Title II (regulated) wireless and wireline phone calls.

      Importantly, functionally equivalent services are defined as “personal wireless services that directly compete against one another” in the 1996-TCA Conference Report. Personal wireless services are defined as “commercial mobile services, unlicensed wireless services, and common carrier wireless exchange access services” in the 1996-TCA. Finally, mobile services is defined as “a radio communication service carried on between mobile stations or receivers and land stations, and by mobile stations communicating among themselves” in the 1996-TCA. None of these definitions include wireless or wireline broadband.

      Signal Strength (dBm) Power Density (µW/m²) Compare vs. 5-Bars Land of . . .
      30 dBm 580,000,000 µW/m²  

      Land of

      (No 1996-TCA Preemption of
      Local Authority)

      25 dBm 180,000,000 µW/m² 100,000,000,000x higher  
      20 dBm 58,000,000 µW/m²    
      15 dBm 18,000,000 µW/m² 10,000,000,000x higher  
      10 dBm 5,800,000 µW/m²    
      5 dBm 1,800,000 µW/m² 1,000,000,000x higher  
      0 dBm 580,000 µW/m²    
      -5 dBm 180,000 µW/m² 100,000,000x higher  
      -10 dBm 58,000 µW/m²    
      -15 dBm 18,000 µW/m² 10,000,000x higher  
      -20 dBm 5,800 µW/m²    
      -25 dBm 1,800 µW/m² 1,000,000x higher  
      -30 dBm 580 µW/m²    
      -35 dBm 180 µW/m² 100,000x higher  
      -40 dBm 58 µW/m²    
      -45 dBm 18 µW/m² 10,000x higher  
      -50 dBm 5.8 µW/m²    
      -55 dBm 1.8 µW/m² 1,000x higher  
      -60 dBm 0.58 µW/m²    
      -65 dBm 0.18 µW/m² 100x higher  
      -70 dBm 0.058 µW/m²    
      -75 dBm 0.018 µW/m² 10x higher  
      -80 dBm 0.0058 µW/m²    
      -85 dBm 0.0018 µW/m² 5 Bars on a cell phone

      Land of

      (1996-TCA Premption)

      -90 dBm 0.00058 µW/m²    
      -95 dBm 0.00018 µW/m² 1/10th lower  
      -100 dBm 0.000058 µW/m²    
      -105 dBm 0.000018 µW/m² 1/100th lower  
      -110 dBm 0.0000058 µW/m²    
      -115 dBm 0.0000018 µW/m² 1/1,000th lower  
      -120 dBm 0.00000058 µW/m²    
      -125 dBm 0.00000018 µW/m² 1/10,000th lower  

      Conclusion: 0.002 µW/m² (-85 dBm) is all the RF microwave radiation that is needed for strong cellular service in a residential neighborhood. A locality can set a maximum power output limit from all frequencies/antennas from a WTF in the public rights-of-way at 0.1 Watt of Effective Radiated Power (ERP) because that provides -85 dBm signal strength at a ½-mile down the street, with five bars on a cell phone and everyone can make a call.

      • 0.002 µW/m² is 5 billion (5,000,000,000) times lower than the scientifically-unsound, FCC RF microwave radiation maximum public exposure guideline of 10,000,000 µW/m².
      • 0.002 µW/m² is still 2 billion (2,000,000,000) times higher than the PicoWatt (0.000000000001 Watt) electrical rates of power that human cell membranes use in regulating many key biological functions.

      The simple math, above, clearly explains why so-called “small” Wireless Telecommunications Facilities (sWTFs) are hazardous and should not be allowed in public rights-of-way in residential zones.

      In any area accessible to the general population, if any Carrier-specific frequency/band/channel achieves a grade of ‘A’ or ‘B’ for Signal Strength, then there is NO NEED for any additional Carrier-specific WTFs

      GradeSignal StrengthStatus
      A — Excellent-90 dBm to -125 dBmOK
      B — Good-80 dBm to -89 dBmOK
      C — Fair-70 dBm to -79 dBmExcessive
      D — Poor-60 dBm to -69 dBmExcessive
      F — FailingExceeds -60 dBmExcessive

      To Balance Needs of the Public and the Wireless Carriers, One Merely Needs to Flip One’s Idea of What Constitutes the Scale of ‘Excellent’ to ‘Poor/Failing’ Grades — This is Why

      The Numbers

      • RSSI – For 2G/3G frequencies: -80dBm is excellent signal, -110dBm is poor signal (1/1000th of -80 dBM)
      • RSSI – For 4G/LTE frequencies: -90dBm is excellent signal, -120dBm is poor or no signal (1/1000th of -90 dBm)
      • RSRQ – For 4G/LTE frequencies: 0 dB is insignificant interference, -20 dB is significant interference (note, this is dB, not dBm, so this is a relative, not an absolute metric)

      Note: Verizon has scheduled to stop selling 3G consumer services on December 31, 2022. Most other wireless carriers have ended 3G consumer services already. Business customers, however, will continue to use select 3G-based services.

      Appendix A: 4G Frequencies Handle All Wireless Phone Calls (i.e.Telecommunications Service);
      5G frequencies are use exclusively for data (i.e. Information Service)

      >>> Top US-based Telecom Attorney wrote on 10/19/22 3:36 PM:

      I explained the routing issue in this excerpt of an email to someone else:

      4G VoLTE calls are routed through the base station, not small cells. This is done for quality of service reasons and to avoid having to deal with multiple hand-offs while the mobile user User Equipment (UE or the mobile phone) is moving through an area. Qualify of service is especially important for 911 voice sessions.

      5G will use the same routing, through what is called "fallback" (the voice session is handled through LTE, not 5G) At some point, the voice session may fully transition to 5G and handle voice, but not right now. All decisions are made on current practices, not the promise of how things might change in the future.

      This may not be clear since is not plain English, but that is what this sentence on p. 8 of says

      "For handover procedures in the NR-NR architecture involving a VoNR call, the gNB-CP initiates and handles all control signalling while maintaining the VoNR call, …."

      Efficient fallback from 5G to EPC (LTE) is described in this 2019 T-Mobile patent. The last two sentences prove the point:

      “5G New Radio (NR) is expected to coexist with 4G Long Term Evolution (LTE) both during the initial deployment phase (providing a seamless transition from 4G LTE to 5G NR) and even later when 5G is widely deployed. For example, heterogenous networks (HetNets) providing for E-UTRAN-NR Dual Connectivity (EN-DC) will exist to provide, for example, better in-building connectivity and indoor coverage using user equipment or terminal equipment simultaneously connected to 5G small cell devices and 4G macro base stations or vice-versa. Multiple migration paths and steps exist for migration to 5G. For instance, an initial 5G deployment using option 3-5G Evolved Packet System (EPS) includes NR non-standalone in the Radio Access Network (RAN). 4G voice (VoLTE) and other IP Multimedia System (IMS) services continue to be used without the need for any core network upgrade. At least initially, a 5G system will not be deployed with full network coverage. Therefore, the 5G system will need to be tightly coupled to an existing 4G VoLTE deployment to provide seamless voice services across the whole 4G+5G network.”

      This also, BTW, demonstrates that when 5G goes in somewhere it will go on top of the existing LTE network. So you are increasing the number of transmitters and thus RF microwave radiation exposure.

      Be aware that if the user has turned on Voice over Wi-Fi then there will be different routing. That call will go on a regular data channel, with reduced quality of service.

      For the foreseeable future there will be a macro cell tower around that manages the voice service control plane and channel, and the core network will determine whether and what bearer channels (voice or other data) will go through the macro or small cell.

      So yes voice is handled at the macro cell towers for all current deployments. Who knows what the future might bring?

      Once again, all local regulation and decisions about the placement, construction, modification and operations of Wireless Telecommunications Facilities (WTFs) of any size or any "G" must be based on substantial written evidence of current practices, and not be based on wireless industry projections of what might happen in the future.

      Now, on regulatory classification. You have likely seen this, but the FCC has held that data service, including texting, is not personal wireless service. But texting (as opposed to basic data) is functionally treated like a telecom service, akin to the old “adjunct to basic” treatment that was used under the FCC’s Computer Inquiry regime. Even so, neither is a part of personal wireless service. They have made this clear several times. The two most applicable are In re Accelerating Wireless Broadband Deployment by Removing Barriers et al., 33 FCC Rcd 9088, 9107, n.95 (Sept. 27, 2018) (“Small Cell Order”) aff’d in part, vacated in part. City of Portland v. United States, 2020 U.S. App. LEXIS 25553 (9th Cir. Aug. 12, 2020) and the 2014 order implementing the Spectrum Act, which highlights the differing regulatory classification and treatment. FCC held that Spectrum Act minor modification (a/k/a exempt facility”) protection extends to all wireless services, including data-only and even private mobile facilities, since the Spectrum Act used the “broader term, ‘wireless.’” In the Matter of Acceleration of Broadband Deployment by Improving Wireless Facilities Siting Policies; Acceleration of Broadband Deployment: Expanding the Reach and Reducing the Cost of Broadband Deployment by Improving Policies Regarding Public Rights of Way and Wireless Facilities Siting; 2012 Biennial Review of Telecommunications Regulations, FCC 14-153, 29 FCC Rcd 12865, 12931, ¶154 (Oct. 2014).

      Appendix B: Radio Terms Detail: SNR, RSSI, RSRP and RSRQ

      In cellular networks of any G, when a mobile device moves from cell to cell and performs cell selection/reselection and handover, it has to measure the signal strength and quality of the neighbor cells. In the process of handover, the LTE specification provides the flexibility of assessing RSRP, RSRQ, or both. RSRQ is used when RSRP is not sufficient to make a reliable handover or cell re-selection decision.

      • SNR = Signal to Interference & Noise Ratio (initiated with the very first radios)
      • RSSI (dBm) = Received Signal Strength Indicator (first initiated for 2G/3G, but applicable to 4G LTE/5G, as well)
      • RSRP (dBm) = Reference Signals Received Power (first initiated for 4G LTE, but applicable to 5G, as well)
      • RSRQ (dB) = Reference Signal Received Quality (first initiated for 4G LTE, but applicable to 5G, as well)

      SNR = Signal to Noise Ratio

      SNR can be understood as the ratio of signal power (desired signal) to undesired signal and noise power. Undesired signals include all external noise and internal noise.

      RSSI = Received Signal Strength Indicator

      The RSSI is the total power obtained by the UE on the entire frequency band, including the power of main signals, co-channel non-serving signals, adjacent-channel interference, and even thermal noise on the specified frequency band. The RSSI is the power of the non-demodulated signal, so the UE can measure power without any synchronization or demodulation.

      The following figure shows an example of downlink radio frames. The red part in the figure indicates the resource elements that are being sent. Blue and sky blue indicate synchronization signals. The green part indicates the MIB (Master Information Block). The white part is the PDSCH, where users send data. The RSSI is the total power of all colors and any possible noise or interference in all these areas.

      RSRP = Reference Signal Recieved Power

      RSRP is a linear average of reference signal power over a specified bandwidth (number of REs). The UE measures one of the most important counters for cell selection, reselection, and handover. Similar to CPICH RSCP in WCDMA.

      In 3GPP 36.214, RSRP is defined as follows:

      “Reference signal received power (RSRP), is defined as the linear average over the power contributions (in [W]) of the resource elements that carry cell-specific reference signals within the considered measurement frequency bandwidth. For RSRP determination the cell-specific reference signals R0 according to TS 36.211 shall be used. If the UE can reliably detect that R1 is available it may use R1 in addition to R0 to determine RSRP.”

      Note: R0 indicates the cell-specific reference signal for antenna port 0. R1 is the cell-specific reference signal of antenna port 1.

      RSRQ = Reference Signal Received Quality

      As defined in 3GPP 36.214, RSRQ is defined as (N x RSRP)/RSSI, where N indicates the number of RBs (resource blocks) over the measured bandwidth.

      RSRQ = N * RSRP/RSSI

      According to the definition, the RSSI includes all types of power, including co-channel serving and non-serving cells, adjacent channel interference, and thermal noise. Therefore, (N x RSRP)/RSSI represents the proportion of the pure RS (reference signal) power to all E-UTRA power received by the UE.

      RSRQ is a derived value of RSRP and RSSI providing information about interference and desired signal strength. Because this is the ratio of two different power values, the RSRQ is in dB and the value is always negative (because the RSSI value is always greater than N x RSRP).

      The UE usually measures and reports the RSRP or RSRQ based on the direction of the RRC message from the network. When the UE reports this value, the actual RSRQ value is used. The UE sends non-negative values ranging from 0 to 34. Each value is mapped to a specific range of real RSRQ values.