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Unformatted text preview: UCSB Spring 2011 ECE 146B: Communications II Lab 2: Simulation of linear modulation in AWGN Assigned: April 11 Due: April 29 (at the beginning of the lab session) Reading: Chapter 4 (linear modulation) and Chapter 6 (Section 6.1 on Gaussian random variables and Q function). We also state and use probability of error expressions from Chapter 6, but reading about how these are derived is not required at this point. Lab Objectives: To implement in complex baseband a linearly modulated system for a variety of signal constellations. To estimate the performance of these schemes for an ideal channel via simulation, and compare with analytical expressions. Laboratory Assignment 0) For this lab, you can either build on your own code from Lab 1, or get a template for the solutions to Lab 1 from the course home page. We will use a trivial channel filter throughout this lab as well. 1) Write a matlab function randbit that generates random bits taking values in { , 1 } (not ± 1) with equal probability. 2) Write the following functions mapping bits to symbols for different signal constellations. Write the functions to allow for vector inputs and outputs. The mapping is said to be a Gray code, or Gray labeling, if the bit map for nearest neighbors in the constellation differ by exactly one bit. In all of the following, choose the bit map to be a Gray code. (a) bpskmap: input a 0 / 1 bit, output a ± 1 bit. (b) qpskmap: input 2 0 / 1 bits, output a symbol taking one of four values in ± 1 ± j . (c) fourpammap: input 2 0 / 1 bits, output a symbol taking one of four values in {± 1 , ± 3 } ....
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This note was uploaded on 09/10/2011 for the course ECE 146B taught by Professor Upamanyumadhow during the Spring '11 term at UC Merced.
 Spring '11
 UpamanyuMadhow

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