//Simple model of Chess Mac protocol for wireless sensor networks //Model by Faranak Heidarian, Julian Schmaltz, Frits Vaandrager, //Version March 30, 2009 //CONSTANTS AND TYPES //number of nodes; we assume N>=2 const int N = 4; //set of node identifiers typedef int[0,N-1] Nodes; //number of slots within one frame const int C = 6; //number of active slots within one frame; we assume N <= n <= C const int n = 4; //transmission slot number; we assume each node has unique active slot tsn[i] in which it transmits const int[0,n-1] tsn[Nodes] = {0,1,2,3}; //number of clock cycles per slot const int k0 = 21; //guard time; we assume 0 < g and 2g < k0 const int g = 10; //tail time; we assume t>0 and g+t+2 <= k0 const int t = 2; //minimal time between two clock ticks; we assume 0< min const int min = 30; //maximal time between two clock ticks; we assume min<= max const int max = 31; //NB We grossly exagerate the clock drift theta; in reality it is approximately 20ppm //CHANNELS broadcast chan start_message[Nodes], tick[Nodes]; //STATE VARIABLES //hardware clock of a node; to keep state space tractable //we assume clocks are reset at the end of each slot int[0,k0-1] clk[Nodes]; //current slot number of a node int[0,C-1] csn[Nodes]; //HISTORY VARIABLES clock y; int[-1,C-1] last = -1; system CLOCK, WSN, SYNCHRONIZER;