Guide
Background
RSSL (Relative Signal Strength Level) is a signal strength calculation designed to make it easier for users to understand if the location of their installation is acceptable or not. For performing surveys on 2G (GSM), CSQ was formerly an easy way to measure the signal strength reading. However, this measurement is not consistent across 3G (UMTS) and 4G (LTE) as CSQ does not measure the entire signal strength band. It merely measures a segment of the
band with discounted sections above and below the traditional CSQ. For example: A CSQ of 1 in 4G relates to 3% using old CSQ calculations but is actually 32% of the entire signal strength. In this scenario it is unlikely you would install a device with a perceived value of 3% but possible at 32%.
RSSL Explained
To ensure that a consistent approach is used to measure all Radio Access Technologies (RAT) - such as 2G, 3G and 4G - a new, more accurate method for calculating percentage of the signal strength has been introduced. RSSL is not based on CSQ readings provided by the radio module alone but is calculated from the raw data received from the network readings. The value is mapped through the whole range and is independent for each RAT. The value calculation includes both signal strength and signal quality measurements.
What Does This Mean?
- The method for obtaining signal level is technology independent.
- Minimum CSQ required for units to register in 2G, 3G and 4G are different. The standards only specify minimum thresholds of each type of measurement required by the UE to report to the core network. The requirements for data transmission depend on a wide range of factors e.g. indoor/outdoor cell, in urban or remote location, proximity to the base station.
- Percentage representation of CSQ is not relevant, accurate or consistent. Figure 1 depicts the summary of the problem. Clearly using CSQ values omits substantial sections of the 3G and 4G band and what is 40% of the CSQ range in 2G is not equivalent in the other RATs. Achieving the equivalent of 40% CSQ in 2G at the other RATS will be very difficult unless there are strong cells in the neighbourhood.
- It is possible to receive signal levels in the discounted CSQ areas, and in fact the 3GPP specifications clearly indicate that it is possible for 4G to operate below a CSQ of 0.
| 2G | 3G | 4G | |||||||
| CSQ Reading | Proposed RSSL (%) |
Remark | CSQ Reading | Proposed RSSL (%) |
Remark | CSQ Reading | Proposed RSSL (%) |
Remark | |
| -140 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 0 | Weak |
| -139 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 1 | Weak |
| -138 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 2 | Weak |
| -137 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 3 | Weak |
| -136 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 4 | Weak |
| -135 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 6 | Weak |
| -134 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 7 | Weak |
| -133 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 8 | Weak |
| -132 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 9 | Weak |
| -131 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 10 | Weak |
| -130 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 11 | Weak |
| -129 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 12 | Weak |
| -128 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 13 | Weak |
| -127 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 15 | Weak |
| -126 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 16 | Weak |
| -125 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 17 | Weak |
| -124 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 18 | Weak |
| -123 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 19 | Weak |
| -122 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 20 | Weak |
| -121 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 21 | Weak |
| -120 | 0 | 0 | Weak | 0 | 0 | Weak | 0 | 22 | Weak |
| -119 | 0 | 0 | Weak | 0 | 2 | Weak | 0 | 24 | Weak |
| -118 | 0 | 0 | Weak | 0 | 3 | Weak | 0 | 25 | Weak |
| -117 | 0 | 0 | Weak | 0 | 5 | Weak | 0 | 26 | Weak |
| -116 | 0 | 0 | Weak | 0 | 6 | Weak | 0 | 27 | Weak |
| -115 | 0 | 0 | Weak | 0 | 8 | Weak | 0 | 28 | Weak |
| -114 | 0 | 0 | Weak | 0 | 9 | Weak | 0 | 29 | Weak |
| -113 | 0 | 0 | Weak | 0 | 11 | Weak | 0 | 30 | Low |
| -112 | 0 | 2 | Weak | 0 | 12 | Weak | 0 | 31 | Low |
| -111 | 1 | 3 | Weak | 1 | 14 | Weak | 1 | 32 | Low |
| -110 | 2 | 5 | Weak | 2 | 15 | Weak | 2 | 34 | Low |
| -109 | 2 | 7 | Weak | 2 | 17 | Weak | 2 | 35 | Low |
| -108 | 3 | 8 | Weak | 3 | 18 | Weak | 3 | 36 | Low |
| -107 | 3 | 10 | Weak | 3 | 20 | Weak | 3 | 37 | Low |
| -106 | 4 | 12 | Weak | 4 | 21 | Weak | 4 | 38 | Low |
| -105 | 4 | 13 | Weak | 4 | 23 | Weak | 4 | 39 | Low |
| -104 | 5 | 15 | Weak | 5 | 24 | Weak | 5 | 40 | Good |
| -103 | 5 | 16 | Weak | 5 | 26 | Weak | 5 | 41 | Good |
| -102 | 6 | 18 | Weak | 6 | 27 | Weak | 6 | 43 | Good |
| -101 | 6 | 20 | Weak | 6 | 29 | Weak | 6 | 44 | Good |
| -100 | 7 | 21 | Weak | 7 | 31 | Low | 7 | 45 | Good |
| -99 | 7 | 23 | Weak | 7 | 32 | Low | 7 | 46 | Good |
| -98 | 8 | 25 | Weak | 8 | 34 | Low | 8 | 47 | Good |
| -97 | 8 | 26 | Weak | 8 | 35 | Low | 8 | 48 | Good |
| -96 | 9 | 28 | Weak | 9 | 37 | Low | 9 | 49 | Good |
| -95 | 9 | 30 | Low | 9 | 38 | Low | 9 | 50 | Good |
| -94 | 10 | 31 | Low | 10 | 40 | Good | 10 | 52 | Good |
| -93 | 10 | 33 | Low | 10 | 41 | Good | 10 | 53 | Good |
| -92 | 11 | 35 | Low | 11 | 43 | Good | 11 | 54 | Good |
| -91 | 11 | 36 | Low | 11 | 44 | Good | 11 | 55 | Good |
| -90 | 12 | 38 | Low | 12 | 46 | Good | 12 | 56 | Good |
| -89 | 12 | 39 | Low | 12 | 47 | Good | 12 | 57 | Good |
| -88 | 13 | 41 | Good | 13 | 49 | Good | 13 | 58 | Good |
| -87 | 13 | 43 | Good | 13 | 50 | Good | 13 | 59 | Good |
| -86 | 14 | 44 | Good | 14 | 52 | Good | 14 | 60 | Strong |
| -85 | 14 | 46 | Good | 14 | 53 | Good | 14 | 62 | Strong |
| -84 | 15 | 48 | Good | 15 | 55 | Good | 15 | 63 | Strong |
| -83 | 15 | 49 | Good | 15 | 56 | Good | 15 | 64 | Strong |
| -82 | 16 | 51 | Good | 16 | 58 | Good | 16 | 65 | Strong |
| -81 | 16 | 53 | Good | 16 | 59 | Good | 16 | 66 | Strong |
| -80 | 17 | 54 | Good | 17 | 61 | Strong | 17 | 67 | Strong |
| -79 | 17 | 56 | Good | 17 | 63 | Strong | 17 | 68 | Strong |
| -78 | 18 | 58 | Good | 18 | 64 | Strong | 18 | 69 | Strong |
| -77 | 18 | 59 | Good | 18 | 66 | Strong | 18 | 71 | Strong |
| -76 | 19 | 61 | Strong | 19 | 67 | Strong | 19 | 72 | Strong |
| -75 | 19 | 63 | Strong | 19 | 69 | Strong | 19 | 73 | Strong |
| -74 | 20 | 64 | Strong | 20 | 70 | Strong | 20 | 74 | Strong |
| -73 | 20 | 66 | Strong | 20 | 72 | Strong | 20 | 75 | Strong |
| -72 | 21 | 67 | Strong | 21 | 73 | Strong | 21 | 76 | Strong |
| -71 | 21 | 69 | Strong | 21 | 75 | Strong | 21 | 77 | Strong |
| -70 | 22 | 71 | Strong | 22 | 76 | Strong | 22 | 78 | Strong |
| -69 | 22 | 72 | Strong | 22 | 78 | Strong | 22 | 80 | Strong |
| -68 | 23 | 74 | Strong | 23 | 79 | Strong | 23 | 81 | Strong |
| -67 | 23 | 76 | Strong | 23 | 81 | Strong | 23 | 82 | Strong |
| -66 | 24 | 77 | Strong | 24 | 82 | Strong | 24 | 83 | Strong |
| -65 | 24 | 79 | Strong | 24 | 84 | Strong | 24 | 84 | Strong |
| -64 | 25 | 81 | Strong | 25 | 85 | Strong | 25 | 85 | Strong |
| -63 | 25 | 82 | Strong | 25 | 87 | Strong | 25 | 86 | Strong |
| -62 | 26 | 84 | Strong | 26 | 88 | Strong | 26 | 87 | Strong |
| -61 | 26 | 86 | Strong | 26 | 90 | Strong | 26 | 88 | Strong |
| -60 | 27 | 87 | Strong | 27 | 92 | Strong | 27 | 90 | Strong |
| -59 | 27 | 89 | Strong | 27 | 93 | Strong | 27 | 91 | Strong |
| -58 | 28 | 91 | Strong | 28 | 95 | Strong | 28 | 92 | Strong |
| -57 | 28 | 92 | Strong | 28 | 96 | Strong | 28 | 93 | Strong |
| -56 | 29 | 94 | Strong | 29 | 98 | Strong | 29 | 94 | Strong |
| -55 | 29 | 95 | Strong | 29 | 99 | Strong | 29 | 95 | Strong |
| -54 | 30 | 97 | Strong | 31 | 100 | Strong | 30 | 96 | Strong |
| -53 | 30 | 99 | Strong | 31 | 100 | Strong | 30 | 97 | Strong |
| -52 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 99 | Strong |
| -51 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -50 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -49 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -48 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -47 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -46 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -45 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -44 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -43 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -42 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -41 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -40 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -39 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -38 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -37 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -36 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -35 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -34 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -33 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -32 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -31 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -30 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -29 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -28 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -27 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -26 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |
| -25 | 31 | 100 | Strong | 31 | 100 | Strong | 31 | 100 | Strong |