Guest Post: Difference between Practical and theoretical SINR

Posted By : Rakhi Roy

Student in National Taipei University,

Communication Engineering Department.

Writer of Blog : Beautiful Bangladesh

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 Signal to Interference plus Noise Ratio SINR is commonly used in wireless communication as a way to measure the quality of wireless connections. In wireless networks, this is commonly defined by path loss. It is calculated as SINR = P / (I + N) where P is signal power, I is interference power and N is noise power and its unit is dB

Most of the people those are related to communication system always prefer high SINR because they think high SINR is good for user and because of high SINR people can upload and download file very quickly. But those who really think this I want to make their concept clear.

Suppose error is indicated as 0 and Correct is indicated as 100 bits.

If Block error rate (BLER) is 10^-1 it means there is a 10% chance of 0(error) bit and 90% chance of 100 bits(Correct ). So here goodput=90 bits

If BLER is 10^-2 it means there is a 10% chance of 0 (error)bit and 99% chance of 100 bits(correct). So here goodput=99 bits

If BLER is 10^-3 it means there is a 0.10% chance of 0 bit (error)and 99.9% chance of 100 bits(correct). So here goodput=99.9 bits

In every case SINR is close to 100 but not exactly 100.All the values are very close to each other         that’s why Throughput vs. SINR curve is almost saturated.

From above discussion it is clear that improving SINR is not affected to the user because in every case there is a very slight difference (90,99,99.9.99.99…)and this difference does not change anything to the user. For a user 99% or 99.9% is not a very big problem.

In wireless communication targeted BLER is 10^-2.So operator always try to keep BLER is 10-2 and they are not very much worried about SINR.

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