Example 11.5 describes a discrete-time smoothing filter with impulse response
![](https://test.transtutors.com/qimg/2f1ec6ca-5290-4878-a210-902472903762.png)
For a particular wide sense stationary input process Xn, the output process Yn is a wide sense stationary random sequence, with µY = 0 and autocorrelation function
![](https://test.transtutors.com/qimg/fe59ccdc-514a-4c05-ace2-27503fa03247.png)
What is the autocorrelation RX [n] of the input Xn?