[LTE] RSSI, RSRP, RSRQ, RSCP, SINR, EC/IO

 

RSSI (Received Signal Strength Indicatior) - 단위 dBm (절대크기)

- 단말에 수신되는 모든 Power의 총 크기

- 신호 세기에 인접한 채널의 간섭, 열 잡음 포함

- 2G (GSM)에서 통신 감도의 척도가 되는 값이다.

In telecommunications, Received Signal Strength Indicator (RSSI) is a measurement of the power present in a received radio signal.

The RSSI of the modem is indicated by a negative dBm value. This value relates to the signal strength of the cellular signal from the tower to the modem. The higher the number, the better the signal. The exact numbers vary between cellular carriers. However, -70 dBm and higher values usually equate to the modem being in an excellent coverage area. The closer to 0 dBm, the stronger the signal. There is a point at which trying to obtain more signal delivers diminishing returns, because the quality of the connection is defined by more values than just RSSI (you will find more information on the other measurements in the Mobile Signal Strength Recommendations page).

2G and 3G signal levels

Excellent (>= -70 dBm)	Strong signal with maximum data speeds
Good (-70 dBm to -85 dBm)	Strong signal with good data speeds
Fair (-86 dBm to -100 dBm)	Fair but useful, fast and reliable data speeds may be attained, but marginal data with drop-outs is possible
Poor (< -100 dBm)	Performance will drop drastically
No signal (-110 dBm)	Disconnection

4G signal levels

Excellent (> -65 dBm)	Strong signal with maximum data speeds
Good (-65 dBm to -75 dBm)	Strong signal with good data speeds
Fair (-75 dBm to -85 dBm)	Fair but useful, fast and reliable data speeds may be attained, but marginal data with drop-outs is possible
Poor (-85 dBm to -95 dBm)	Performance will drop drastically
No signal (<= -95 dBm)	Disconnection

 

RSRP and RSRQ

Reference Signals Received Power (RSRP) and Reference Signal Received Quality (RSRQ) are key measures of signal level and quality for modern LTE networks. In cellular networks, when a mobile device moves from cell to cell and performs cell selection/reselection and handover, it has to measure the signal strength/quality of the neighbor cells. In the procedure of handover, the LTE specification provides the flexibility of using RSRP, RSRQ, or both.

 

RSRP (Reference Signal Received Power) - 단위 dBm (절대크기)

- 단말에 수신되는 Reference Signal의 Power

- RSRP is applicable in both RRC_idle and RRC_connected modes

. LTE에서는 Hard H/O이기 때문에 효율적, 기지국 근처 RSRP ↑

- 3G (UMTS / WCDMA)에 들어오면서 통신 감도의 척도가 되는 값으로,
쉽게 내 PCS에 대한 Signal Power라고 보면 됩니다.

- 고려되어지는 측정주파수 대역안에서의 cell-specific한 기준 신호(reference signal)를 보내는 resource element들의

파워 분포(power contribution)에 대한 linear average와 동일한 cell power로 결정된다.

만약 UE가 diversity를 사용한다면, 기록된 값은 모든 diversity path상의 power의 선형적인 합과 동일하다고 보면 된다.

- Reference Signal Received Power is an RSSI type of measurement. It is the power of the LTE Reference Signals spread over the full bandwidth and narrowband. A minimum of -20 dB SINR (of the S-Synch channel) is needed to detect RSRP/RSRQ.

Excellent (>= -80 dBm)	Strong signal with maximum data speeds
Good (-80 dBm to -90 dBm)	Strong signal with good data speeds
Fair to poor (-90 dBm to -100 dBm)	Reliable data speeds may be attained, but marginal data with drop-outs is possible. When this value gets close to -100, performance will drop drastically
No signal (<= -100 dBm)	Disnonnection

 

RSRQ (Reference Signal Received Quality) - 단위 dB (상대크기)

- 단말에 수신되는 Power 대비 Reference Signal Power의 비

- RSRQ is only application in RRC_connected mode

- RSRQ = (RSRP/RSSI) * nuber of RB

- 신호 세기와 함께 간섭 등을 측정에 포함시키기 때문에, RSRP와 더불어 H/O 결정 지표

. 원하는 신호에 대해 많은 정보(인접채널간섭, 열잡음 등) + RB가 포함되어 있기 때문에

  실제 환경이 반영된 지표. 단, RSRP/RSSI의 비, RB의 수가 일정하기 때문에 지표 자체가 큰 변동 없음

- 4G (LTE, LTEA, LGE-A)에 들어오면서 통신 감도의 척도가 되는 값이다.

- Reference Signal Received Quality: Quality considering also RSSI and the number of used Resource Blocks (N) RSRQ = (N * RSRP) / RSSI measured over the same bandwidth. RSRQ is a C/I type of measurement and it indicates the quality of the received reference signal. The RSRQ measurement provides additional information when RSRP is not sufficient to make a reliable handover or cell reselection decision.

Excellent (>= -10 dB)	Strong signal with maximum data speeds
Good (-10 dB to -15 dB)	Strong signal with good data speeds
Fair to poor (-15 dB to -20 dB)	Reliable data speeds may be attained, but marginal data with drop-outs is possible. When this value gets close to -20, performance will drop drastically
No signal (<= -20 dB)	Disconnection

 

RSCP (Received Signal Code Power)

In the UMTS cellular communication system, Received Signal Code Power (RSCP) denotes the power measured by a receiver on a particular physical communication channel. It is used as an indication of signal strength, as a handover criterion, in downlink power control, and to calculate path loss. In CDMA systems, a physical channel corresponds to a particular spreading code, hence the name (Received signal code power). RSCP is also called Receiver Side Call Power.

While RSCP can be defined generally for any CDMA system, it is more specifically used in UMTS. Also, while RSCP can be measured in principle on the downlink as well as on the uplink, it is only defined for the downlink and thus presumed to be measured by the UE (User Equipment) and reported to the Node B.

Excellent (-60 to 0)	Strong signal with maximum data speeds
Good (-75 to -60)	Strong signal with good data speeds
Fair (-85 to -75)	Fair but useful, fast and reliable data speeds may be attained
Poor (-95 to -85)	Marginal data with drop-outs is possible
Very poor (-124 to -95)	Performance will drop drastically, closer to -124 disconnects are likely

 

SINR (Signal-to-Interference-plus-Noise Ratio)

In information theory and telecommunication engineering, the Signal-to-Interference-plus-Noise Ratio (SINR) is a quantity used to give theoretical upper bounds on channel capacity (or the rate of information transfer) in wireless communication systems such as networks. Analogous to the SNR used often in wired communications systems, the SINR is defined as the power of a certain signal of interest divided by the sum of the interference power (from all the other interfering signals) and the power of some background noise. If the power of noise term is zero, then the SINR reduces to the signal-to-interference ratio (SIR). Conversely, zero interference reduces the SINR to the signal-to-noise ratio (SNR), which is used less often when developing mathematical models of wireless networks such as cellular networks.

SINR is commonly used in wireless communication as a way to measure the quality of wireless connections. Typically, the energy of a signal fades with distance, which is referred to as a path loss in wireless networks. Conversely, in wired networks the existence of a wired path between the sender or transmitter and the receiver determines the correct reception of data. In a wireless network one has to take other factors into account (e.g. the background noise, interfering strength of other simultaneous transmission). The concept of SINR attempts to create a representation of this aspect.

Excellent (>= 20 dB)	Strong signal with maximum data speeds
Good (13 dB to 20 dB)	Strong signal with good data speeds
Fair to poor (0 dB to 13 dB)	Reliable data speeds may be attained, but marginal data with drop-outs is possible. When this value gets close to 0, performance will drop drastically
No signal (<= 0 dB)	Disconnection

 

EC/IO

The EC/IO is a measure of the quality/cleanliness of the signal from the tower to the modem and indicates the signal-tonoise ratio (the ratio of the received/good energy to the interference/bad energy). It is measured in decibels (dB). In a perfect world, where there is no true interference, the interference level is equal to the noise level resulting in an EC/IO = 0 dB. Once the EC/IO is above ~ -7.0 dB, your connection is going to suffer.

There are several factors that can contribute to a higher EC/IO value, including florescent lighting, electric motors, equipment, power supplies, bad/poor cabling, trees, hills, buildings, walls, shorted connectors, inaccurate antenna alignment, wrong antenna polarization, congestion at the tower, etc.

Excellent (0 to -6)	Strong signal with maximum data speeds
Good (-7 to -10)	Strong signal with good data speeds
Fair to poor (-11 to -20)	Reliable data speeds may be attained, but marginal data with drop-outs is possible. When this value gets close to -20, performance will drop drastically

 

[ NOTE ]

1. E-UTRA RSSI(Received Signal Strength Indicator)는

모든 source들(co-channel serving and non-serving cells, adjacent channel interference, thermal noise rtc)로부터

UE에 의해 관찰되어지는 모든 수신 광대역 파워를 구성한다.

2. Power Control이 EPRE(Energy Per Resource Element)를 결정한다.

그 Resource element energy term은 CP insertion에 전의 에너지로 표시된다.

또한, 그것은 modulation scheme에 의한 모든 constellation 지점들을 포함한 평균 에너지를 표시한다.

The RSRP is comparable to the CPICH RSCP measurement in WCDMA. This measurement of the signal strength of an LTE cell helps to rank between the different cells as input for handover and cell reselection decisions. The RSRP is the average of the power of all resource elements which carry cell-specific reference signals over the entire bandwidth. It can therefore only be measured in the OFDM symbols carrying reference symbols.

The RSRQ measurement provides additional information when RSRP is not sufficient to make a reliable handover or cell reselection decision. RSRQ is the ratio between the RSRP and the Received Signal Strength Indicator (RSSI), and depending on the measurement bandwidth, means the number of resource blocks. RSSI is the total received wideband power including all interference and thermal noise. As RSRQ combines signal strength as well as interference level, this measurement value provides additional help for mobility decisions

P.S)
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[Reference]

https://wiki.teltonika.lt/view/Mobile_Signal_Strength_Recommendations

Mobile Signal Strength Recommendations - Wiki Knowledge Base | Teltonika