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M. G. Gouda                                                   CS 356
Fall 2004                                                     Homework 2
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1.[2 points] Solve Problem 7 in Chapter 5.

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2.[2 points] Solve Problem 3 in Chapter 5.

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3.[3 points] Consider a network that consists of processes p and q[i:0..n-1]. 
  At any given time, process p can establish a connection with at most one q[i],
  using the connection protocol that uses timeout in Section 6.1. The data 
  structure for process p is as follows:

  process p
  
  const   n
  input   m       : integer  {m>0}
  var     conp    : boolean, {init. false}
          cansend : 0..m, 
          x       : 0..n-1   {init. any}
  par     y       : 0..n-1
  
  Design the actions in process p.
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4.[3 points] The length of a data block in the corruption detection protocol 
  that uses parity bits in Section 8.1 is defined in terms of two constants m 
  and n. It is required to compute the optimal values of m and n for this 
  protocol, given the follwing facts. Let b be the total number of data and 
  parity bits in a data block, and let r be the maximum number of bits in a 
  corruption burst. The value of b is in the range from 1 to 299 and the 
  value of r depends on the chosen value of b as follows. 

  If b is chosen in the range 1..99 	then 	r should be 10
  If b is chosen in the range 100..199	then 	r should be 15
  If b is chosen in the range 200..299	then 	r should be 24

  (Hint: The optimal values for m and n are those that minimize the ratio 
  (k/(m*n)), where k is the number of parity bits and m*n is the number of 
  data bits in a data block.)

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