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Signal Analyser - RSSL Explained

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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