CS 536 (Park) Assignment II Due: Sep. 24 (Fri.), 2004Submission instructions: Please type your answers and submit electronic copies using turnin by 5pm on the due date.You may use any number of word processing software (e.g., Framemaker, Word, LATEX), but the final output must bein pdf or ps format that uses standard fonts (a practical test is to check if the pdf/ps file prints on a CS Departmentprinter without problem). For experiments and programming assignments that involve output to terminal, please usescript to record the output and submit the output file. Use gnuplot to plot graphs. Use ps2gif to convert a eps/psplot to gif format (e.g., for inclusion in Word).PROBLEM 1Read Sections 2.1–2.5 from P & D.PROBLEM 2 (20 pts)“Bandwidth”, as used in networking, is an overloaded term. Describe and define the different meanings/usages ofthe term (at least 5). For each case, provide an example where it comes into play. For example, Nyquist’s samplingtheorem is one where “bandwidth” appears. So it does in gigabit Ethernet (“bandwidth” 1 Gbps).PROBLEM 3 (30 pts)Describe the architectural workings of the iPod + FM transmitter + radio based “digital communication system” forwirelessly sending data bits discussed in class. Your specification should lay down what physical layer transmissionscheme was used—assume we have three sets of iPods, FM transmitters, and radios operating concurrently onradio frequencies 88.3 MHz, 88.5 MHz, and 88.7 MHz (of course, only one was used in the experiment)—whatcoding/framing we used, and if senders and receivers need clocks (if they do why, if not, why not). Your descriptionmust be technical, employing the techniques, machinery, and terms studied thus far. Calculate the data rate (bps) thatsix humans—three senders and three receivers—operating the communication system according to your specificationwould achieve. Assuming that the “human baud rate” is limited by at most 1 pressing of the pause button persecond (those playing computer games may exhibit a faster performance), what other architectural design features(you may not change the 3 sender/3 receiver set-up) may be changed to improve performance, i.e., increase the bitrate? The top three designs with respect to claimed speed will be asked to undergo benchmarking to verify theirclaims. Benchmarking will be done with one iPod. Those that do come within 10% of their performance spec willbe given 10 bonus pts.PROBLEM 4 (40 pts)(a) Consider the direct sequence CDMA example for N = 4 users, r = 4, and chipping codes(1, 1, 1, 1), (−1, −1, 1, 1), (−1, 1, −1, 1), (−1, 1, 1, −1)discussed in class. Assuming that each user wishes to send a single bit—user 1 bit 0, user 2 bit 1, user 3 bit 1, anduser 4 bit 0—use the DS-CDMA scheme to compute the (combined) transmission “signal” z. From z, show howeach user retrieves, i.e., decodes, his/her bit. Specify how majority voting, formulated in the EXOR 0/1-bit context,manifests itself in the last step of the 1/−1-bit context, i.e., what step needs to be carried out to determine if thetransmitted bit is a 1 (1) or −1 (0).(b) Suppose z gets corrupted in flight where a noise vector ε =(1, 0, 0, −1) gets added to yield z0= z + ε. Performthe decoding for each user based on the received signal z0. Are the users able to decode the correct bit value using theprocedure employed in (a)? Give a smallest noise vector—the size of a vector is defined as the sum of the absolutevalues of the components—that causes a decoding failure for at least one user.(c) Suppose we get greedy and aim to support a 5th user (i.e., N = 5) while keeping r = 4. Devise a 5th chippingcode y5such that in the absence of channel noise decoding works correctly for the example bits to be sent (assumethe 5th user wishes to send 1). Assuming you have found such a chipping code, how is it possible to transmit fiveusers’ data bits simultaneously without using five orthogonal chipping codes? What are the possible limitations ofyour N =5/r = 4 CDMA system?PROBLEM 5 (50 = 40 + 10 pts)(a) Extend the client/server application from Assignment I such that any UNIX command—you may ignorecommand-line arguments—can be requested by the client to be executed on the server and its output returnedto the client. The request format should be of the formprocess-ID # command #Your client program is to take as its command-line argument the name of the UNIX command to be executed. Testyour program by first running the server application in the background, then executing four copies of the client inthe background “simultaneously” with arguments date, ls, ps, and hostname, respectively. Use script to recordyour interaction/screen output.(b) The client/server application is an instance of a concurrent server where a server process parses incomingrequests, then hands off the actual task to a spawned child process. In an iterative server, the task is carried outby the server process itself. What are the pros/cons of an iterative server vis-`a-vis a concurrent server? Can theclient/server program be implemented as an interative server?