I have got a solution of a question but i m unable to understand this equation

Q (a) > 99 %

so a < -2.33

i know Q function and know to read its table but how -2.33 has come here.plz explain

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- Mar 14th 2010, 03:11 AMmoonnightingalehelp for Q function query
I have got a solution of a question but i m unable to understand this equation

Q (a) > 99 %

so a < -2.33

i know Q function and know to read its table but how -2.33 has come here.plz explain - Mar 14th 2010, 06:08 PMmr fantastic
- Mar 15th 2010, 03:45 AMmoonnightingale
I have attached the solution.

Kindly tell me why he has written -2.33 - Mar 15th 2010, 05:35 PMmr fantastic
- Mar 16th 2010, 09:18 AMmoonnightingale
The question is

In this problem we will explore the impact of different log-normal shadowing parameters on outage probability.Consider a a cellular system where the received signal power is distributed according to a log-normaldistribution with mean*μ*dBm and standard deviation*σψ*dBm. Assume thereceived signal power must beabove 10 dBm for acceptable performance.

(a) What is the outage probability when the log-normal distribution has*μψ*= 15 dBm and*σψ*= 8dBm?

(b) For*σψ*= 4dBm, what value of*μψ*is required such that the outage probability is less than 1%, a typical

value for high-quality PCS systems?

Solution is

*attached file*

- Mar 16th 2010, 12:20 PMrubicQ function query
1 - Q(a) < 0.01

1 + Q(-a) < 0.01

Q(-a) > 0.99

from table

-a > 2.33, which is same as a < -2.33

hope it helps - Mar 16th 2010, 03:13 PMmoonnightingale
ur last statement stillnot clear