12.10. The message signal y[n] in Figure P12.10 is to be encrypted and transmitted across a...
Fantastic news! We've Found the answer you've been seeking!
Question:
Transcribed Image Text:
12.10. The message signal y[n] in Figure P12.10 is to be encrypted and transmitted across a noisy channel, then decrypted and filtered at the receiver. We model y[n] as a zero-mean WSS random process with autocorrelation function Ryy[m] and corresponding PSD Syy(e). The signal p[n] is used for both the encryption at the transmitter and the decryption at the receiver, and is an i.i.d. process that takes the values +1 or -1 with equal probability at each time; it is independent of the process y[-]. Note that p²[n] = 1 for all n. The transmitted signal q[n] is the product p[n]y[n]. Message signal y[n] Encryption/decryption signal p[n] q[n] Channel noise Noncausal. Wiener filter H(e) y[n] Figure P12.10 (a) Determine the respective means up and μg of the processes p[n] and q[n], their respective autocorrelations Rpp[m] and Rag[m] (expressed in terms of Ryy[-]), and also the cross-correlation Ryg[m] between the message signal and the transmitted signal. Would an intruder who was able to intercept the transmitted process q[-] have any use for a (possibly noncausal) linear estimator of y[n] based on measurements of q[-]? Explain your answer. The channel adds a noise signal v[n] to the transmitted signal, so that the received signal is q[n]+v[n] = p[n]y[n]+v[n]. Assume v[n] is a zero-mean and white WSS process, with Ry[m] = o²8[m]; sup- pose it is uncorrelated with y[-], and both processes are independent of p[-]. We assume, as indicated in Figure P12.10, that the intended receiver knows the specific encryption signal p[n], i.e., the specific sample function from the ensem- ble that was used for encryption. If there was no channel noise (i.e., if we had v[n] = 0), the decryption would then simply involve multiplying the received signal by p[n] because p[n]q[n] = p[n] (p[n]y[n]) =p²[n]y[n] = y[n], where the last equality is a consequence of having p²[n] = 1. In the presence of noise, we can still attempt to decrypt in the same manner, but will follow it up by a further stage of filtering. The signal to be filtered is thus (b) Determine x, Rx[m], and Ryx[m]. (c) Suppose the filter at the receiver is to be a (stable) noncausal Wiener filter, constructed so as to produce the LMMSE estimate [n] of y[n]. Determine the frequency response H(e) of this filter, and explicitly check that it is what you would expect it to be in the two limiting cases of o2 = 0 and o →∞o. Also write an expression, in terms of Syy(e) and o?, for the mean square error obtained with this filter, and explicitly check that it is what you would expect it to be in the preceding two limiting cases. 12.10. The message signal y[n] in Figure P12.10 is to be encrypted and transmitted across a noisy channel, then decrypted and filtered at the receiver. We model y[n] as a zero-mean WSS random process with autocorrelation function Ryy[m] and corresponding PSD Syy(e). The signal p[n] is used for both the encryption at the transmitter and the decryption at the receiver, and is an i.i.d. process that takes the values +1 or -1 with equal probability at each time; it is independent of the process y[-]. Note that p²[n] = 1 for all n. The transmitted signal q[n] is the product p[n]y[n]. Message signal y[n] Encryption/decryption signal p[n] q[n] Channel noise Noncausal. Wiener filter H(e) y[n] Figure P12.10 (a) Determine the respective means up and μg of the processes p[n] and q[n], their respective autocorrelations Rpp[m] and Rag[m] (expressed in terms of Ryy[-]), and also the cross-correlation Ryg[m] between the message signal and the transmitted signal. Would an intruder who was able to intercept the transmitted process q[-] have any use for a (possibly noncausal) linear estimator of y[n] based on measurements of q[-]? Explain your answer. The channel adds a noise signal v[n] to the transmitted signal, so that the received signal is q[n]+v[n] = p[n]y[n]+v[n]. Assume v[n] is a zero-mean and white WSS process, with Ry[m] = o²8[m]; sup- pose it is uncorrelated with y[-], and both processes are independent of p[-]. We assume, as indicated in Figure P12.10, that the intended receiver knows the specific encryption signal p[n], i.e., the specific sample function from the ensem- ble that was used for encryption. If there was no channel noise (i.e., if we had v[n] = 0), the decryption would then simply involve multiplying the received signal by p[n] because p[n]q[n] = p[n] (p[n]y[n]) =p²[n]y[n] = y[n], where the last equality is a consequence of having p²[n] = 1. In the presence of noise, we can still attempt to decrypt in the same manner, but will follow it up by a further stage of filtering. The signal to be filtered is thus (b) Determine x, Rx[m], and Ryx[m]. (c) Suppose the filter at the receiver is to be a (stable) noncausal Wiener filter, constructed so as to produce the LMMSE estimate [n] of y[n]. Determine the frequency response H(e) of this filter, and explicitly check that it is what you would expect it to be in the two limiting cases of o2 = 0 and o →∞o. Also write an expression, in terms of Syy(e) and o?, for the mean square error obtained with this filter, and explicitly check that it is what you would expect it to be in the preceding two limiting cases.
Expert Answer:
Posted Date:
Students also viewed these algorithms questions
-
A transmitter sends a signal X and a receiver makes the observation Y = X + Z, whare Z is a receiver noise that is independent of X and E[X] = E[Z] = 0. Since the average power of the signal is E[X2]...
-
Determine the system function for the noncausal IIR Wiener filter for the signal given in Problem 11.24 and the corresponding MMSEn0.
-
A random process has a PSD function given by (a) Find the absolute bandwidth. (b) Find the 3 dB bandwidth. (c) Find the RMS bandwidth. Can you generalize your result to a spectrum of the form Where...
-
Multiple Select Question Select all that apply Identify what might happen if a particular department were eliminated. (Check all that apply.) Multiple select question. Many of the indirect expenses...
-
1, 2, 4, 4 We have provided simple data sets for you to practice the basics of finding measures of variation. For each data set, determine the a. Range. b. Sample standard deviation.
-
The Manning Company has financial statements as shown next, which are representative of the companys historical average. The firm is expecting a 35 percent increase in sales next year, and management...
-
Refer to Exercise 4.80 and obtain the (a) mean; (b) variance; (c) standard deviation for the number of requests for conference rooms. Data From Exercise 4.80 4.80 Upon reviewing recent use of...
-
The balance sheet of Lamont Bros. follows: a. What portions of Lamonts assets were provided by debt, contributed capital, and earned capital? Reduce contributed capital by the cost of the treasury...
-
4. What is the net present value of the following stream of cash flows assuming the opportunity cost rate is 12%? Solve NPV using each cash flow and the NPV function in Excel (use basic PV/FV...
-
Patterson, Inc. has provided detals of Its actual cost data for the month. The Controller has asked you to compute the basic variances and the impact of those variances on unit costs. Use the...
-
Engineering Economics question. Solve using both tabulated factors. QUESTION NO. 13 Very Light Jets (VLJs) are one-pilot, two-engine jets that weigh 10,000 pounds or less and have only five or six...
-
What is the output of the RightTriangle program? package shapes; A. rt B. irt C. The code does not compile due to line g1. D. The code does not compile due to line g2. E. The code does not compile...
-
What change is needed to make Secret well encapsulated? A. Change number to use a protected access modifier. B. Change number to use a public access modifier. C. Declare a private constructor. D....
-
Which statement about encapsulation is not true? A. Encapsulation allows putting extra logic in the getter and setter methods. B. Encapsulation can use immutable instance variables in the...
-
Given the following method signature, which classes can call it? void run(String government) A. Classes in other packages B. Classes in the same package C. Subclasses in a different package D. All...
-
Fill in the blanks: It is possible to extend a(n) ______________ but not a(n) ______________. (Choose two.) A. interface, abstract class B. anonymous class, static nested class C. abstract class,...
-
When a firewall examines a packet passing through it, it will drop the packet if it is ________. A) a provable attack packet B) a suspicious packet C) not a provable attack packet D) a stateful packet
-
Economic feasibility is an important guideline in designing cost accounting systems. Do you agree? Explain.
-
What are a manager's resources?
-
What are the three levels of management?
-
What is the glass ceiling?
Study smarter with the SolutionInn App