SINR: Signal to Interference plus Noise Ratio refers to the ratio of the strength of the received useful signal to the strength of the received interference signal (noise and interference);It can be simply understood as "signal to noise ratio".
Chinese name
Signal to interference plus noise ratio
Foreign name
Signal to Interference plus Noise Ratio
Foreign abbreviations
SINR
Chinese abbreviation
Signal-to-noise ratio
Interpretation
The ratio of the strength of the received useful signal to the strength of the received interference signal
The ratio of signal to interference plus noise initially appears in multiuser detection.Suppose there are two users 1 and 2, transmitting two signals from the antenna (code orthogonality in CDMA and spectrum orthogonality in ofdm, which is used to distinguish different data sent to two users);At the receiving end, user 1 receives the data sent by the transmitting antenna to user 1, which is a useful signal. It also receives the data sent by the transmitting antenna to user 2, which is interference interference, as well as noise.
SINR often appears because of many reasonsdecodingInterference cancellation technology, such as BLAST space-time structure, is adopted.stayV-BLASTindecodingFirst decode the data with high signal to interference noise ratio (layered), then subtract (cancel) the decoded data, and so on until all data are decoded.Here, SINR is an important parameter.
There are many proposals in 3GPPMIMO technology, such as PARC (per antenna rate control), PGRC (per group rate control), etc., the CQI (channel quality indicator) needs to be used to feedback the channel specific to the transmitter, which is used to adjust the data rate of the transmission antenna to achieveadaptive modulation 。If the complete characteristics of the channel can be estimated and fed back, that is, the channel matrix H is of course the best.However, in practical systems, especially MIMO systems, it is unrealistic to accurately and timely estimate the channel matrix H, and due to the limitation of feedback channels, feedback information can not be too much.Therefore, most of the 3GPP proposals use SINR as feedback information foradaptive modulation Control parameters of.
There are different methods for SINR calculation in different systems.You can see the relevant proposals and articles.Here is a simple method, which is not accurate but easy to understand and compile.If there are two transmit antennas 1 and 2, the receiver needs to receive the data from antenna 1. If antenna 2 is interference, SINR1=P1/(P2+2PN). P1 and P2 represent the power of transmit antennas 1 and 2 respectively, and PN represents the noise power.
SINR has become an important indicator of the receiver, which puts forward higher requirements for the sensitivity and anti-interference ability of the equipment.CDMA system is a system with limited interference. The multi-user interference in the system has a great impact on the system. SINR should be considered in the specific design.This is because the spread spectrum code of CDMA system is not completely orthogonal and has a certain correlation value. When the terminal positions of multiple users are relatively close, the interference between terminals will be relatively large.At the same time, since the CDMA base stations use the same frequency, there will be interference between different base stations[1]。
SINR formula[4]
Expression
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To understand SINR, you can first understand its close relative, SNR (Signal Noise Ratio), which is the ratio of signal to noise.It is estimated that readers who have learned the basics of communication are familiar with this concept, which appears in the following famous Shannon formula.
C=B×log₂（1+S/N）（bit/s）
Although Shannon's formula is not used to calculate the signal-to-noise ratio, it contains the concept and application of signal-to-noise ratio.It shows that the information transmission rate C is not only related to the channel bandwidth B, but also related to the signal-to-noise ratio S/N.To some extent, this shows that the signal to noise ratio is a key factor affecting communication quality.
SINR，It is one more I than SNR,Signal to Interference plus Noise Ratio，Signal to interference plus noise ratio refers to the ratio of the strength of the received useful signal to the strength of the received interference signal (noise plus interference), which can also be simply understood as "signal to noise ratio".It needs to be clear that Noise and Interference are two different concepts. Generally, Noise refers to noise with a very wide frequency band, which is mainly determined and generated by the thermal performance of the receiver.As the name implies, Interference refers to interference, such as signals from other systems, whose spectrum is much narrower than Noise.
At present, there is no specific definition of SINR in the agreement, which is usually expressed as follows:
SINR=Signal / (Interference+Noise);
S: The measured power of useful signals, mainly focusing on the following signals and channels: RS, PDSCH;
1: The measured signal or channel interference signal power, including interference from other cells of the system and interference from different systems:
N: Low noise, related to the specific measurement bandwidth and receiver noise figure.
SINR edge experience value:
TD-LTE office, 99% area, SINR>- 3dB
Outfield, 99.25% area, SINR>- 3dB[2]
LTE-SINR definition
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Downlink SINR calculation:
Distribute the power on RB evenly to each RE
SINR of downlink RS=RS receiving power/(interference power+noise power)=S/(I+N) RS receiving power=RS transmitting power * link loss
Interference power=sum of adjacent cell power received on RE occupied by RS
Uplink SINR calculation:
The uplink SRS of each UE is placed in the last block of a subframe.The frequency domain interval of SRS is two equivalent subcarriers.Therefore, the interference of SRS of one UE only comes from SRS of other UEs.SINR=SRS receiving power/(interference power+noise power) SRS receiving power=SRS transmitting power * link loss interference power=sum of SRS receiving power of all UEs in the adjacent cell[3]
