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Fixed a bug: formulas are now handled (more) correctly. Added some WLAN examples.
Fixed a bug: formulas are now handled (more) correctly. Added some WLAN examples.
Former-commit-id: 4b87ffc99f
tempestpy_adaptions
dehnert
11 years ago
12 changed files with 1799 additions and 445 deletions
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41examples/mdp/wlan/wlan0_collide.nm
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221examples/mdp/wlan/wlan1_collide.nm
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75examples/mdp/wlan/wlan2_collide.nm
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235examples/mdp/wlan/wlan3_collide.nm
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252examples/mdp/wlan/wlan4_collide.nm
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286examples/mdp/wlan/wlan5_collide.nm
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351examples/mdp/wlan/wlan6_collide.nm
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1examples/mdp/wlan/wlanX_1.cexprop
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1examples/mdp/wlan/wlanX_4.cexprop
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1examples/mdp/wlan/wlanX_6.cexprop
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6src/parser/prismparser/VariableState.cpp
@ -0,0 +1,221 @@ |
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// WLAN PROTOCOL (two stations) |
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// discrete time model |
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// gxn/jzs 20/02/02 |
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|
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mdp |
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|
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// COLLISIONS |
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const int COL; // maximum number of collisions |
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|
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// TIMING CONSTRAINTS |
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// we have used the FHSS parameters |
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// then scaled by the value of ASLOTTIME |
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const int ASLOTTIME = 1; |
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const int DIFS = 3; // due to scaling can be either 2 or 3 which is modelled by a non-deterministic choice |
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const int VULN = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
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const int TRANS_TIME_MAX; // scaling up |
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const int TRANS_TIME_MIN = 4; // scaling down |
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const int ACK_TO = 6; |
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const int ACK = 4; // due to scaling can be either 3 or 4 which is modelled by a non-deterministic choice |
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const int SIFS = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
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// maximum constant used in timing constraints + 1 |
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const int TIME_MAX = max(ACK_TO,TRANS_TIME_MAX)+1; |
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|
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// CONTENTION WINDOW |
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// CWMIN =15 & CWMAX =31 |
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// this means that MAX_BACKOFF IS 2 |
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const int MAX_BACKOFF = 1; |
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|
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//-----------------------------------------------------------------// |
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// THE MEDIUM/CHANNEL |
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|
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// FORMULAE FOR THE CHANNEL |
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// channel is busy |
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formula busy = c1>0 | c2>0; |
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// channel is free |
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formula free = c1=0 & c2=0; |
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|
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module medium |
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|
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// number of collisions |
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col : [0..COL]; |
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|
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// medium status |
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c1 : [0..2]; |
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c2 : [0..2]; |
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// ci corresponds to messages associated with station i |
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// 0 nothing being sent |
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// 1 being sent correctly |
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// 2 being sent garbled |
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|
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// begin sending message and nothing else currently being sent |
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[send1] c1=0 & c2=0 -> (c1'=1); |
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[send2] c2=0 & c1=0 -> (c2'=1); |
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|
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// begin sending message and something is already being sent |
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// in this case both messages become garbled |
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[send1] c1=0 & c2>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
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[send2] c2=0 & c1>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
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|
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// finish sending message |
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[finish1] c1>0 -> (c1'=0); |
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[finish2] c2>0 -> (c2'=0); |
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|
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endmodule |
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|
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//-----------------------------------------------------------------// |
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// STATION 1 |
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module station1 |
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// clock for station 1 |
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x1 : [0..TIME_MAX]; |
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|
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// local state |
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s1 : [1..12]; |
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// 1 sense |
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// 2 wait until free before setting backoff |
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// 3 wait for DIFS then set slot |
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// 4 set backoff |
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// 5 backoff |
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// 6 wait until free in backoff |
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// 7 wait for DIFS then resume backoff |
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// 8 vulnerable |
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// 9 transmit |
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// 11 wait for SIFS and then ACK |
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// 10 wait for ACT_TO |
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// 12 done |
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// BACKOFF |
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// separate into slots |
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slot1 : [0..1]; |
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backoff1 : [0..15]; |
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|
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// BACKOFF COUNTER |
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bc1 : [0..MAX_BACKOFF]; |
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// SENSE |
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// let time pass |
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[time] s1=1 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
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// ready to transmit |
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[] s1=1 & (x1=DIFS | x1=DIFS-1) -> (s1'=8) & (x1'=0); |
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// found channel busy so wait until free |
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[] s1=1 & busy -> (s1'=2) & (x1'=0); |
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// WAIT UNTIL FREE BEFORE SETTING BACKOFF |
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// let time pass (no need for the clock x1 to change) |
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[time] s1=2 & busy -> (s1'=2); |
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// find that channel is free so check its free for DIFS before setting backoff |
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[] s1=2 & free -> (s1'=3); |
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// WAIT FOR DIFS THEN SET BACKOFF |
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// let time pass |
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[time] s1=3 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
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// found channel busy so wait until free |
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[] s1=3 & busy -> (s1'=2) & (x1'=0); |
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// start backoff first uniformly choose slot |
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// backoff counter 0 |
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[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=0 -> (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
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// backoff counter 1 |
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[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=1 -> 1/2 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/2 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
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// SET BACKOFF (no time can pass) |
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// chosen slot now set backoff |
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[] s1=4 -> 1/16 : (s1'=5) & (backoff1'=0 ) |
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+ 1/16 : (s1'=5) & (backoff1'=1 ) |
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+ 1/16 : (s1'=5) & (backoff1'=2 ) |
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+ 1/16 : (s1'=5) & (backoff1'=3 ) |
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+ 1/16 : (s1'=5) & (backoff1'=4 ) |
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+ 1/16 : (s1'=5) & (backoff1'=5 ) |
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+ 1/16 : (s1'=5) & (backoff1'=6 ) |
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+ 1/16 : (s1'=5) & (backoff1'=7 ) |
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+ 1/16 : (s1'=5) & (backoff1'=8 ) |
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+ 1/16 : (s1'=5) & (backoff1'=9 ) |
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+ 1/16 : (s1'=5) & (backoff1'=10) |
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+ 1/16 : (s1'=5) & (backoff1'=11) |
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+ 1/16 : (s1'=5) & (backoff1'=12) |
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+ 1/16 : (s1'=5) & (backoff1'=13) |
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+ 1/16 : (s1'=5) & (backoff1'=14) |
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+ 1/16 : (s1'=5) & (backoff1'=15); |
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// BACKOFF |
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// let time pass |
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[time] s1=5 & x1<ASLOTTIME & free -> (x1'=min(x1+1,TIME_MAX)); |
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// decrement backoff |
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[] s1=5 & x1=ASLOTTIME & backoff1>0 -> (s1'=5) & (x1'=0) & (backoff1'=backoff1-1); |
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[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1>0 -> (s1'=5) & (x1'=0) & (backoff1'=15) & (slot1'=slot1-1); |
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// finish backoff |
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[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1=0 -> (s1'=8) & (x1'=0); |
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// found channel busy |
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[] s1=5 & busy -> (s1'=6) & (x1'=0); |
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// WAIT UNTIL FREE IN BACKOFF |
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// let time pass (no need for the clock x1 to change) |
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[time] s1=6 & busy -> (s1'=6); |
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// find that channel is free |
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[] s1=6 & free -> (s1'=7); |
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|
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// WAIT FOR DIFS THEN RESUME BACKOFF |
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// let time pass |
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[time] s1=7 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
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// resume backoff (start again from previous backoff) |
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[] s1=7 & (x1=DIFS | x1=DIFS-1) -> (s1'=5) & (x1'=0); |
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// found channel busy |
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[] s1=7 & busy -> (s1'=6) & (x1'=0); |
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|
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// VULNERABLE |
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// let time pass |
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[time] s1=8 & x1<VULN -> (x1'=min(x1+1,TIME_MAX)); |
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// move to transmit |
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[send1] s1=8 & (x1=VULN | x1=VULN-1) -> (s1'=9) & (x1'=0); |
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// TRANSMIT |
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// let time pass |
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[time] s1=9 & x1<TRANS_TIME_MAX -> (x1'=min(x1+1,TIME_MAX)); |
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// finish transmission successful |
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[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=1 -> (s1'=10) & (x1'=0); |
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// finish transmission garbled |
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[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=2 -> (s1'=11) & (x1'=0); |
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// WAIT FOR SIFS THEN WAIT FOR ACK |
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|
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// WAIT FOR SIFS i.e. c1=0 |
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// check channel and busy: go into backoff |
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[] s1=10 & c1=0 & x1=0 & busy -> (s1'=2); |
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// chEck channel and free: let time pass |
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[time] s1=10 & c1=0 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
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// let time pass |
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// following guard is always false as SIFS=1 |
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// [time] s1=10 & c1=0 & x1>0 & x1<SIFS -> (x1'=min(x1+1,TIME_MAX)); |
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// ack is sent after SIFS (since SIFS-1=0 add condition that channel is free) |
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[send1] s1=10 & c1=0 & (x1=SIFS | (x1=SIFS-1 & free)) -> (s1'=10) & (x1'=0); |
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|
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// WAIT FOR ACK i.e. c1=1 |
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// let time pass |
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[time] s1=10 & c1=1 & x1<ACK -> (x1'=min(x1+1,TIME_MAX)); |
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// get acknowledgement so packet sent correctly and move to done |
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[finish1] s1=10 & c1=1 & (x1=ACK | x1=ACK-1) -> (s1'=12) & (x1'=0) & (bc1'=0); |
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|
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// WAIT FOR ACK_TO |
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// check channel and busy: go into backoff |
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[] s1=11 & x1=0 & busy -> (s1'=2); |
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// check channel and free: let time pass |
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[time] s1=11 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
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// let time pass |
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[time] s1=11 & x1>0 & x1<ACK_TO -> (x1'=min(x1+1,TIME_MAX)); |
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// no acknowledgement (go to backoff waiting DIFS first) |
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[] s1=11 & x1=ACK_TO -> (s1'=3) & (x1'=0); |
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// DONE |
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[time] s1=12 -> (s1'=12); |
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endmodule |
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// ---------------------------------------------------------------------------- // |
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// STATION 2 (rename STATION 1) |
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module |
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station2=station1[x1=x2, |
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s1=s2, |
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s2=s1, |
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c1=c2, |
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c2=c1, |
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slot1=slot2, |
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backoff1=backoff2, |
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bc1=bc2, |
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send1=send2, |
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finish1=finish2] |
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endmodule |
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// ---------------------------------------------------------------------------- // |
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label "twoCollisions" = col=2; |
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label "fourCollisions" = col=4; |
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label "sixCollisions" = col=6; |
@ -0,0 +1,235 @@ |
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// WLAN PROTOCOL (two stations) |
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// discrete time model |
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// gxn/jzs 20/02/02 |
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|
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mdp |
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|
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// COLLISIONS |
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const int COL; // maximum number of collisions |
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|
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// TIMING CONSTRAINTS |
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// we have used the FHSS parameters |
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// then scaled by the value of ASLOTTIME |
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const int ASLOTTIME = 1; |
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const int DIFS = 3; // due to scaling can be either 2 or 3 which is modelled by a non-deterministic choice |
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const int VULN = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
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const int TRANS_TIME_MAX; // scaling up |
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const int TRANS_TIME_MIN = 4; // scaling down |
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const int ACK_TO = 6; |
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const int ACK = 4; // due to scaling can be either 3 or 4 which is modelled by a non-deterministic choice |
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const int SIFS = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
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// maximum constant used in timing constraints + 1 |
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const int TIME_MAX = max(ACK_TO,TRANS_TIME_MAX)+1; |
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|
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// CONTENTION WINDOW |
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// CWMIN =15 & CWMAX =127 |
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// this means that MAX_BACKOFF IS 3 |
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const int MAX_BACKOFF = 3; |
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//-----------------------------------------------------------------// |
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// THE MEDIUM/CHANNEL |
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// FORMULAE FOR THE CHANNEL |
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// channel is busy |
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formula busy = c1>0 | c2>0; |
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// channel is free |
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formula free = c1=0 & c2=0; |
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module medium |
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// number of collisions |
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col : [0..COL]; |
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// medium status |
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c1 : [0..2]; |
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c2 : [0..2]; |
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// ci corresponds to messages associated with station i |
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// 0 nothing being sent |
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// 1 being sent correctly |
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// 2 being sent garbled |
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|
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// begin sending message and nothing else currently being sent |
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[send1] c1=0 & c2=0 -> (c1'=1); |
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[send2] c2=0 & c1=0 -> (c2'=1); |
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|
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// begin sending message and something is already being sent |
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// in this case both messages become garbled |
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[send1] c1=0 & c2>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
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[send2] c2=0 & c1>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
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// finish sending message |
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[finish1] c1>0 -> (c1'=0); |
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[finish2] c2>0 -> (c2'=0); |
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endmodule |
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|
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//-----------------------------------------------------------------// |
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// STATION 1 |
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module station1 |
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// clock for station 1 |
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x1 : [0..TIME_MAX]; |
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|
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// local state |
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s1 : [1..12]; |
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// 1 sense |
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// 2 wait until free before setting backoff |
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// 3 wait for DIFS then set slot |
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// 4 set backoff |
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// 5 backoff |
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// 6 wait until free in backoff |
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// 7 wait for DIFS then resume backoff |
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// 8 vulnerable |
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// 9 transmit |
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// 11 wait for SIFS and then ACK |
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// 10 wait for ACT_TO |
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// 12 done |
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// BACKOFF |
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// separate into slots |
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slot1 : [0..7]; |
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backoff1 : [0..15]; |
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|
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// BACKOFF COUNTER |
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bc1 : [0..MAX_BACKOFF]; |
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// SENSE |
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// let time pass |
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[time] s1=1 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
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// ready to transmit |
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[] s1=1 & (x1=DIFS | x1=DIFS-1) -> (s1'=8) & (x1'=0); |
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// found channel busy so wait until free |
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[] s1=1 & busy -> (s1'=2) & (x1'=0); |
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// WAIT UNTIL FREE BEFORE SETTING BACKOFF |
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// let time pass (no need for the clock x1 to change) |
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[time] s1=2 & busy -> (s1'=2); |
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// find that channel is free so check its free for DIFS before setting backoff |
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[] s1=2 & free -> (s1'=3); |
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// WAIT FOR DIFS THEN SET BACKOFF |
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// let time pass |
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[time] s1=3 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
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// found channel busy so wait until free |
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[] s1=3 & busy -> (s1'=2) & (x1'=0); |
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// start backoff first uniformly choose slot |
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// backoff counter 0 |
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[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=0 -> (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
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// backoff counter 1 |
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[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=1 -> 1/2 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/2 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
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// backoff counter 2 |
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[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=2 -> 1/4 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
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// backoff counter 3 |
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[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=3 -> 1/8 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=4) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=5) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=6) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
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+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=7) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
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// SET BACKOFF (no time can pass) |
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// chosen slot now set backoff |
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[] s1=4 -> 1/16 : (s1'=5) & (backoff1'=0 ) |
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+ 1/16 : (s1'=5) & (backoff1'=1 ) |
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+ 1/16 : (s1'=5) & (backoff1'=2 ) |
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+ 1/16 : (s1'=5) & (backoff1'=3 ) |
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+ 1/16 : (s1'=5) & (backoff1'=4 ) |
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+ 1/16 : (s1'=5) & (backoff1'=5 ) |
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+ 1/16 : (s1'=5) & (backoff1'=6 ) |
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+ 1/16 : (s1'=5) & (backoff1'=7 ) |
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+ 1/16 : (s1'=5) & (backoff1'=8 ) |
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+ 1/16 : (s1'=5) & (backoff1'=9 ) |
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+ 1/16 : (s1'=5) & (backoff1'=10) |
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+ 1/16 : (s1'=5) & (backoff1'=11) |
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+ 1/16 : (s1'=5) & (backoff1'=12) |
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+ 1/16 : (s1'=5) & (backoff1'=13) |
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+ 1/16 : (s1'=5) & (backoff1'=14) |
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+ 1/16 : (s1'=5) & (backoff1'=15); |
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// BACKOFF |
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// let time pass |
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[time] s1=5 & x1<ASLOTTIME & free -> (x1'=min(x1+1,TIME_MAX)); |
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// decrement backoff |
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[] s1=5 & x1=ASLOTTIME & backoff1>0 -> (s1'=5) & (x1'=0) & (backoff1'=backoff1-1); |
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[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1>0 -> (s1'=5) & (x1'=0) & (backoff1'=15) & (slot1'=slot1-1); |
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// finish backoff |
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[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1=0 -> (s1'=8) & (x1'=0); |
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// found channel busy |
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[] s1=5 & busy -> (s1'=6) & (x1'=0); |
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// WAIT UNTIL FREE IN BACKOFF |
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// let time pass (no need for the clock x1 to change) |
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[time] s1=6 & busy -> (s1'=6); |
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// find that channel is free |
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[] s1=6 & free -> (s1'=7); |
|||
|
|||
// WAIT FOR DIFS THEN RESUME BACKOFF |
|||
// let time pass |
|||
[time] s1=7 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// resume backoff (start again from previous backoff) |
|||
[] s1=7 & (x1=DIFS | x1=DIFS-1) -> (s1'=5) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=7 & busy -> (s1'=6) & (x1'=0); |
|||
|
|||
// VULNERABLE |
|||
// let time pass |
|||
[time] s1=8 & x1<VULN -> (x1'=min(x1+1,TIME_MAX)); |
|||
// move to transmit |
|||
[send1] s1=8 & (x1=VULN | x1=VULN-1) -> (s1'=9) & (x1'=0); |
|||
// TRANSMIT |
|||
// let time pass |
|||
[time] s1=9 & x1<TRANS_TIME_MAX -> (x1'=min(x1+1,TIME_MAX)); |
|||
// finish transmission successful |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=1 -> (s1'=10) & (x1'=0); |
|||
// finish transmission garbled |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=2 -> (s1'=11) & (x1'=0); |
|||
// WAIT FOR SIFS THEN WAIT FOR ACK |
|||
|
|||
// WAIT FOR SIFS i.e. c1=0 |
|||
// check channel and busy: go into backoff |
|||
[] s1=10 & c1=0 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=10 & c1=0 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
// following guard is always false as SIFS=1 |
|||
// [time] s1=10 & c1=0 & x1>0 & x1<SIFS -> (x1'=min(x1+1,TIME_MAX)); |
|||
// ack is sent after SIFS (since SIFS-1=0 add condition that channel is free) |
|||
[send1] s1=10 & c1=0 & (x1=SIFS | (x1=SIFS-1 & free)) -> (s1'=10) & (x1'=0); |
|||
|
|||
// WAIT FOR ACK i.e. c1=1 |
|||
// let time pass |
|||
[time] s1=10 & c1=1 & x1<ACK -> (x1'=min(x1+1,TIME_MAX)); |
|||
// get acknowledgement so packet sent correctly and move to done |
|||
[finish1] s1=10 & c1=1 & (x1=ACK | x1=ACK-1) -> (s1'=12) & (x1'=0) & (bc1'=0); |
|||
|
|||
// WAIT FOR ACK_TO |
|||
// check channel and busy: go into backoff |
|||
[] s1=11 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=11 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
[time] s1=11 & x1>0 & x1<ACK_TO -> (x1'=min(x1+1,TIME_MAX)); |
|||
// no acknowledgement (go to backoff waiting DIFS first) |
|||
[] s1=11 & x1=ACK_TO -> (s1'=3) & (x1'=0); |
|||
|
|||
// DONE |
|||
[time] s1=12 -> (s1'=12); |
|||
endmodule |
|||
|
|||
// ---------------------------------------------------------------------------- // |
|||
// STATION 2 (rename STATION 1) |
|||
module |
|||
station2=station1[x1=x2, |
|||
s1=s2, |
|||
s2=s1, |
|||
c1=c2, |
|||
c2=c1, |
|||
slot1=slot2, |
|||
backoff1=backoff2, |
|||
bc1=bc2, |
|||
send1=send2, |
|||
finish1=finish2] |
|||
endmodule |
|||
// ---------------------------------------------------------------------------- // |
|||
|
|||
label "twoCollisions" = col=2; |
|||
label "fourCollisions" = col=4; |
|||
label "sixCollisions" = col=6; |
@ -0,0 +1,252 @@ |
|||
// WLAN PROTOCOL (two stations) |
|||
// discrete time model |
|||
// gxn/jzs 20/02/02 |
|||
|
|||
mdp |
|||
|
|||
// COLLISIONS |
|||
const int COL; // maximum number of collisions |
|||
|
|||
// TIMING CONSTRAINTS |
|||
// we have used the FHSS parameters |
|||
// then scaled by the value of ASLOTTIME |
|||
const int ASLOTTIME = 1; |
|||
const int DIFS = 3; // due to scaling can be either 2 or 3 which is modelled by a non-deterministic choice |
|||
const int VULN = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
|||
const int TRANS_TIME_MAX; // scaling up |
|||
const int TRANS_TIME_MIN = 4; // scaling down |
|||
const int ACK_TO = 6; |
|||
const int ACK = 4; // due to scaling can be either 3 or 4 which is modelled by a non-deterministic choice |
|||
const int SIFS = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
|||
// maximum constant used in timing constraints + 1 |
|||
const int TIME_MAX = max(ACK_TO,TRANS_TIME_MAX)+1; |
|||
|
|||
// CONTENTION WINDOW |
|||
// CWMIN =15 & CWMAX =255 |
|||
// this means that MAX_BACKOFF IS 4 |
|||
const int MAX_BACKOFF = 4; |
|||
|
|||
//-----------------------------------------------------------------// |
|||
// THE MEDIUM/CHANNEL |
|||
|
|||
// FORMULAE FOR THE CHANNEL |
|||
// channel is busy |
|||
formula busy = c1>0 | c2>0; |
|||
// channel is free |
|||
formula free = c1=0 & c2=0; |
|||
|
|||
module medium |
|||
|
|||
// number of collisions |
|||
col : [0..COL]; |
|||
|
|||
// medium status |
|||
c1 : [0..2]; |
|||
c2 : [0..2]; |
|||
// ci corresponds to messages associated with station i |
|||
// 0 nothing being sent |
|||
// 1 being sent correctly |
|||
// 2 being sent garbled |
|||
|
|||
// begin sending message and nothing else currently being sent |
|||
[send1] c1=0 & c2=0 -> (c1'=1); |
|||
[send2] c2=0 & c1=0 -> (c2'=1); |
|||
|
|||
// begin sending message and something is already being sent |
|||
// in this case both messages become garbled |
|||
[send1] c1=0 & c2>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
|||
[send2] c2=0 & c1>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
|||
|
|||
// finish sending message |
|||
[finish1] c1>0 -> (c1'=0); |
|||
[finish2] c2>0 -> (c2'=0); |
|||
|
|||
endmodule |
|||
|
|||
//-----------------------------------------------------------------// |
|||
// STATION 1 |
|||
module station1 |
|||
// clock for station 1 |
|||
x1 : [0..TIME_MAX]; |
|||
|
|||
// local state |
|||
s1 : [1..12]; |
|||
// 1 sense |
|||
// 2 wait until free before setting backoff |
|||
// 3 wait for DIFS then set slot |
|||
// 4 set backoff |
|||
// 5 backoff |
|||
// 6 wait until free in backoff |
|||
// 7 wait for DIFS then resume backoff |
|||
// 8 vulnerable |
|||
// 9 transmit |
|||
// 11 wait for SIFS and then ACK |
|||
// 10 wait for ACT_TO |
|||
// 12 done |
|||
// BACKOFF |
|||
// separate into slots |
|||
slot1 : [0..15]; |
|||
backoff1 : [0..15]; |
|||
|
|||
// BACKOFF COUNTER |
|||
bc1 : [0..MAX_BACKOFF]; |
|||
// SENSE |
|||
// let time pass |
|||
[time] s1=1 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// ready to transmit |
|||
[] s1=1 & (x1=DIFS | x1=DIFS-1) -> (s1'=8) & (x1'=0); |
|||
// found channel busy so wait until free |
|||
[] s1=1 & busy -> (s1'=2) & (x1'=0); |
|||
// WAIT UNTIL FREE BEFORE SETTING BACKOFF |
|||
// let time pass (no need for the clock x1 to change) |
|||
[time] s1=2 & busy -> (s1'=2); |
|||
// find that channel is free so check its free for DIFS before setting backoff |
|||
[] s1=2 & free -> (s1'=3); |
|||
// WAIT FOR DIFS THEN SET BACKOFF |
|||
// let time pass |
|||
[time] s1=3 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// found channel busy so wait until free |
|||
[] s1=3 & busy -> (s1'=2) & (x1'=0); |
|||
// start backoff first uniformly choose slot |
|||
// backoff counter 0 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=0 -> (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 1 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=1 -> 1/2 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/2 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 2 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=2 -> 1/4 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 3 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=3 -> 1/8 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=4) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=5) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=6) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=7) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 4 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=4 -> 1/16 : (s1'=4) & (x1'=0) & (slot1'=0 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=1 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=2 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=3 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=4 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=5 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=6 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=7 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=8 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=9 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=10) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=11) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=12) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=13) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=14) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=15) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// SET BACKOFF (no time can pass) |
|||
// chosen slot now set backoff |
|||
[] s1=4 -> 1/16 : (s1'=5) & (backoff1'=0 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=1 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=2 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=3 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=4 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=5 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=6 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=7 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=8 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=9 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=10) |
|||
+ 1/16 : (s1'=5) & (backoff1'=11) |
|||
+ 1/16 : (s1'=5) & (backoff1'=12) |
|||
+ 1/16 : (s1'=5) & (backoff1'=13) |
|||
+ 1/16 : (s1'=5) & (backoff1'=14) |
|||
+ 1/16 : (s1'=5) & (backoff1'=15); |
|||
// BACKOFF |
|||
// let time pass |
|||
[time] s1=5 & x1<ASLOTTIME & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// decrement backoff |
|||
[] s1=5 & x1=ASLOTTIME & backoff1>0 -> (s1'=5) & (x1'=0) & (backoff1'=backoff1-1); |
|||
[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1>0 -> (s1'=5) & (x1'=0) & (backoff1'=15) & (slot1'=slot1-1); |
|||
// finish backoff |
|||
[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1=0 -> (s1'=8) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=5 & busy -> (s1'=6) & (x1'=0); |
|||
// WAIT UNTIL FREE IN BACKOFF |
|||
// let time pass (no need for the clock x1 to change) |
|||
[time] s1=6 & busy -> (s1'=6); |
|||
// find that channel is free |
|||
[] s1=6 & free -> (s1'=7); |
|||
|
|||
// WAIT FOR DIFS THEN RESUME BACKOFF |
|||
// let time pass |
|||
[time] s1=7 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// resume backoff (start again from previous backoff) |
|||
[] s1=7 & (x1=DIFS | x1=DIFS-1) -> (s1'=5) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=7 & busy -> (s1'=6) & (x1'=0); |
|||
|
|||
// VULNERABLE |
|||
// let time pass |
|||
[time] s1=8 & x1<VULN -> (x1'=min(x1+1,TIME_MAX)); |
|||
// move to transmit |
|||
[send1] s1=8 & (x1=VULN | x1=VULN-1) -> (s1'=9) & (x1'=0); |
|||
// TRANSMIT |
|||
// let time pass |
|||
[time] s1=9 & x1<TRANS_TIME_MAX -> (x1'=min(x1+1,TIME_MAX)); |
|||
// finish transmission successful |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=1 -> (s1'=10) & (x1'=0); |
|||
// finish transmission garbled |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=2 -> (s1'=11) & (x1'=0); |
|||
// WAIT FOR SIFS THEN WAIT FOR ACK |
|||
|
|||
// WAIT FOR SIFS i.e. c1=0 |
|||
// check channel and busy: go into backoff |
|||
[] s1=10 & c1=0 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=10 & c1=0 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
// following guard is always false as SIFS=1 |
|||
// [time] s1=10 & c1=0 & x1>0 & x1<SIFS -> (x1'=min(x1+1,TIME_MAX)); |
|||
// ack is sent after SIFS (since SIFS-1=0 add condition that channel is free) |
|||
[send1] s1=10 & c1=0 & (x1=SIFS | (x1=SIFS-1 & free)) -> (s1'=10) & (x1'=0); |
|||
|
|||
// WAIT FOR ACK i.e. c1=1 |
|||
// let time pass |
|||
[time] s1=10 & c1=1 & x1<ACK -> (x1'=min(x1+1,TIME_MAX)); |
|||
// get acknowledgement so packet sent correctly and move to done |
|||
[finish1] s1=10 & c1=1 & (x1=ACK | x1=ACK-1) -> (s1'=12) & (x1'=0) & (bc1'=0); |
|||
|
|||
// WAIT FOR ACK_TO |
|||
// check channel and busy: go into backoff |
|||
[] s1=11 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=11 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
[time] s1=11 & x1>0 & x1<ACK_TO -> (x1'=min(x1+1,TIME_MAX)); |
|||
// no acknowledgement (go to backoff waiting DIFS first) |
|||
[] s1=11 & x1=ACK_TO -> (s1'=3) & (x1'=0); |
|||
|
|||
// DONE |
|||
[time] s1=12 -> (s1'=12); |
|||
endmodule |
|||
|
|||
// ---------------------------------------------------------------------------- // |
|||
// STATION 2 (rename STATION 1) |
|||
module |
|||
station2=station1[x1=x2, |
|||
s1=s2, |
|||
s2=s1, |
|||
c1=c2, |
|||
c2=c1, |
|||
slot1=slot2, |
|||
backoff1=backoff2, |
|||
bc1=bc2, |
|||
send1=send2, |
|||
finish1=finish2] |
|||
endmodule |
|||
// ---------------------------------------------------------------------------- // |
|||
|
|||
label "twoCollisions" = col=2; |
|||
label "fourCollisions" = col=4; |
|||
label "sixCollisions" = col=6; |
@ -0,0 +1,286 @@ |
|||
// WLAN PROTOCOL (two stations) |
|||
// discrete time model |
|||
// gxn/jzs 20/02/02 |
|||
|
|||
mdp |
|||
|
|||
// COLLISIONS |
|||
const int COL; // maximum number of collisions |
|||
|
|||
// TIMING CONSTRAINTS |
|||
// we have used the FHSS parameters |
|||
// then scaled by the value of ASLOTTIME |
|||
const int ASLOTTIME = 1; |
|||
const int DIFS = 3; // due to scaling can be either 2 or 3 which is modelled by a non-deterministic choice |
|||
const int VULN = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
|||
const int TRANS_TIME_MAX; // scaling up |
|||
const int TRANS_TIME_MIN = 4; // scaling down |
|||
const int ACK_TO = 6; |
|||
const int ACK = 4; // due to scaling can be either 3 or 4 which is modelled by a non-deterministic choice |
|||
const int SIFS = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
|||
// maximum constant used in timing constraints + 1 |
|||
const int TIME_MAX = max(ACK_TO,TRANS_TIME_MAX)+1; |
|||
|
|||
// CONTENTION WINDOW |
|||
// CWMIN =15 & CWMAX =511 |
|||
// this means that MAX_BACKOFF IS 5 |
|||
const int MAX_BACKOFF = 5; |
|||
|
|||
//-----------------------------------------------------------------// |
|||
// THE MEDIUM/CHANNEL |
|||
|
|||
// FORMULAE FOR THE CHANNEL |
|||
// channel is busy |
|||
formula busy = c1>0 | c2>0; |
|||
// channel is free |
|||
formula free = c1=0 & c2=0; |
|||
|
|||
module medium |
|||
|
|||
// number of collisions |
|||
col : [0..COL]; |
|||
|
|||
// medium status |
|||
c1 : [0..2]; |
|||
c2 : [0..2]; |
|||
// ci corresponds to messages associated with station i |
|||
// 0 nothing being sent |
|||
// 1 being sent correctly |
|||
// 2 being sent garbled |
|||
|
|||
// begin sending message and nothing else currently being sent |
|||
[send1] c1=0 & c2=0 -> (c1'=1); |
|||
[send2] c2=0 & c1=0 -> (c2'=1); |
|||
|
|||
// begin sending message and something is already being sent |
|||
// in this case both messages become garbled |
|||
[send1] c1=0 & c2>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
|||
[send2] c2=0 & c1>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
|||
|
|||
// finish sending message |
|||
[finish1] c1>0 -> (c1'=0); |
|||
[finish2] c2>0 -> (c2'=0); |
|||
|
|||
endmodule |
|||
|
|||
//-----------------------------------------------------------------// |
|||
// STATION 1 |
|||
module station1 |
|||
// clock for station 1 |
|||
x1 : [0..TIME_MAX]; |
|||
|
|||
// local state |
|||
s1 : [1..12]; |
|||
// 1 sense |
|||
// 2 wait until free before setting backoff |
|||
// 3 wait for DIFS then set slot |
|||
// 4 set backoff |
|||
// 5 backoff |
|||
// 6 wait until free in backoff |
|||
// 7 wait for DIFS then resume backoff |
|||
// 8 vulnerable |
|||
// 9 transmit |
|||
// 11 wait for SIFS and then ACK |
|||
// 10 wait for ACT_TO |
|||
// 12 done |
|||
// BACKOFF |
|||
// separate into slots |
|||
slot1 : [0..31]; |
|||
backoff1 : [0..15]; |
|||
|
|||
// BACKOFF COUNTER |
|||
bc1 : [0..MAX_BACKOFF]; |
|||
// SENSE |
|||
// let time pass |
|||
[time] s1=1 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// ready to transmit |
|||
[] s1=1 & (x1=DIFS | x1=DIFS-1) -> (s1'=8) & (x1'=0); |
|||
// found channel busy so wait until free |
|||
[] s1=1 & busy -> (s1'=2) & (x1'=0); |
|||
// WAIT UNTIL FREE BEFORE SETTING BACKOFF |
|||
// let time pass (no need for the clock x1 to change) |
|||
[time] s1=2 & busy -> (s1'=2); |
|||
// find that channel is free so check its free for DIFS before setting backoff |
|||
[] s1=2 & free -> (s1'=3); |
|||
// WAIT FOR DIFS THEN SET BACKOFF |
|||
// let time pass |
|||
[time] s1=3 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// found channel busy so wait until free |
|||
[] s1=3 & busy -> (s1'=2) & (x1'=0); |
|||
// start backoff first uniformly choose slot |
|||
// backoff counter 0 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=0 -> (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 1 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=1 -> 1/2 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/2 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 2 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=2 -> 1/4 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 3 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=3 -> 1/8 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=4) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=5) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=6) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=7) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 4 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=4 -> 1/16 : (s1'=4) & (x1'=0) & (slot1'=0 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=1 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=2 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=3 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=4 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=5 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=6 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=7 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=8 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=9 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=10) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=11) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=12) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=13) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=14) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=15) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 5 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=5 -> 1/32 : (s1'=4) & (x1'=0) & (slot1'=0 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=1 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=2 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=3 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=4 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=5 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=6 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=7 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=8 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=9 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=10) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=11) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=12) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=13) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=14) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=15) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=16) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=17) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=18) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=19) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=20) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=21) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=22) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=23) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=24) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=25) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=26) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=27) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=28) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=29) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=30) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=31) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
|
|||
// SET BACKOFF (no time can pass) |
|||
// chosen slot now set backoff |
|||
[] s1=4 -> 1/16 : (s1'=5) & (backoff1'=0 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=1 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=2 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=3 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=4 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=5 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=6 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=7 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=8 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=9 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=10) |
|||
+ 1/16 : (s1'=5) & (backoff1'=11) |
|||
+ 1/16 : (s1'=5) & (backoff1'=12) |
|||
+ 1/16 : (s1'=5) & (backoff1'=13) |
|||
+ 1/16 : (s1'=5) & (backoff1'=14) |
|||
+ 1/16 : (s1'=5) & (backoff1'=15); |
|||
// BACKOFF |
|||
// let time pass |
|||
[time] s1=5 & x1<ASLOTTIME & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// decrement backoff |
|||
[] s1=5 & x1=ASLOTTIME & backoff1>0 -> (s1'=5) & (x1'=0) & (backoff1'=backoff1-1); |
|||
[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1>0 -> (s1'=5) & (x1'=0) & (backoff1'=15) & (slot1'=slot1-1); |
|||
// finish backoff |
|||
[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1=0 -> (s1'=8) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=5 & busy -> (s1'=6) & (x1'=0); |
|||
// WAIT UNTIL FREE IN BACKOFF |
|||
// let time pass (no need for the clock x1 to change) |
|||
[time] s1=6 & busy -> (s1'=6); |
|||
// find that channel is free |
|||
[] s1=6 & free -> (s1'=7); |
|||
|
|||
// WAIT FOR DIFS THEN RESUME BACKOFF |
|||
// let time pass |
|||
[time] s1=7 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// resume backoff (start again from previous backoff) |
|||
[] s1=7 & (x1=DIFS | x1=DIFS-1) -> (s1'=5) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=7 & busy -> (s1'=6) & (x1'=0); |
|||
|
|||
// VULNERABLE |
|||
// let time pass |
|||
[time] s1=8 & x1<VULN -> (x1'=min(x1+1,TIME_MAX)); |
|||
// move to transmit |
|||
[send1] s1=8 & (x1=VULN | x1=VULN-1) -> (s1'=9) & (x1'=0); |
|||
// TRANSMIT |
|||
// let time pass |
|||
[time] s1=9 & x1<TRANS_TIME_MAX -> (x1'=min(x1+1,TIME_MAX)); |
|||
// finish transmission successful |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=1 -> (s1'=10) & (x1'=0); |
|||
// finish transmission garbled |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=2 -> (s1'=11) & (x1'=0); |
|||
// WAIT FOR SIFS THEN WAIT FOR ACK |
|||
|
|||
// WAIT FOR SIFS i.e. c1=0 |
|||
// check channel and busy: go into backoff |
|||
[] s1=10 & c1=0 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=10 & c1=0 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
// following guard is always false as SIFS=1 |
|||
// [time] s1=10 & c1=0 & x1>0 & x1<SIFS -> (x1'=min(x1+1,TIME_MAX)); |
|||
// ack is sent after SIFS (since SIFS-1=0 add condition that channel is free) |
|||
[send1] s1=10 & c1=0 & (x1=SIFS | (x1=SIFS-1 & free)) -> (s1'=10) & (x1'=0); |
|||
|
|||
// WAIT FOR ACK i.e. c1=1 |
|||
// let time pass |
|||
[time] s1=10 & c1=1 & x1<ACK -> (x1'=min(x1+1,TIME_MAX)); |
|||
// get acknowledgement so packet sent correctly and move to done |
|||
[finish1] s1=10 & c1=1 & (x1=ACK | x1=ACK-1) -> (s1'=12) & (x1'=0) & (bc1'=0); |
|||
|
|||
// WAIT FOR ACK_TO |
|||
// check channel and busy: go into backoff |
|||
[] s1=11 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=11 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
[time] s1=11 & x1>0 & x1<ACK_TO -> (x1'=min(x1+1,TIME_MAX)); |
|||
// no acknowledgement (go to backoff waiting DIFS first) |
|||
[] s1=11 & x1=ACK_TO -> (s1'=3) & (x1'=0); |
|||
|
|||
// DONE |
|||
[time] s1=12 -> (s1'=12); |
|||
endmodule |
|||
|
|||
// ---------------------------------------------------------------------------- // |
|||
// STATION 2 (rename STATION 1) |
|||
module |
|||
station2=station1[x1=x2, |
|||
s1=s2, |
|||
s2=s1, |
|||
c1=c2, |
|||
c2=c1, |
|||
slot1=slot2, |
|||
backoff1=backoff2, |
|||
bc1=bc2, |
|||
send1=send2, |
|||
finish1=finish2] |
|||
endmodule |
|||
// ---------------------------------------------------------------------------- // |
|||
|
|||
label "twoCollisions" = col=2; |
|||
label "fourCollisions" = col=4; |
|||
label "sixCollisions" = col=6; |
@ -0,0 +1,351 @@ |
|||
// WLAN PROTOCOL (two stations) |
|||
// discrete time model |
|||
// gxn/jzs 20/02/02 |
|||
|
|||
mdp |
|||
|
|||
// COLLISIONS |
|||
const int COL; // maximum number of collisions |
|||
|
|||
// TIMING CONSTRAINTS |
|||
// we have used the FHSS parameters |
|||
// then scaled by the value of ASLOTTIME |
|||
const int ASLOTTIME = 1; |
|||
const int DIFS = 3; // due to scaling can be either 2 or 3 which is modelled by a non-deterministic choice |
|||
const int VULN = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
|||
const int TRANS_TIME_MAX; // scaling up |
|||
const int TRANS_TIME_MIN = 4; // scaling down |
|||
const int ACK_TO = 6; |
|||
const int ACK = 4; // due to scaling can be either 3 or 4 which is modelled by a non-deterministic choice |
|||
const int SIFS = 1; // due to scaling can be either 0 or 1 which is modelled by a non-deterministic choice |
|||
// maximum constant used in timing constraints + 1 |
|||
const int TIME_MAX = max(ACK_TO,TRANS_TIME_MAX)+1; |
|||
|
|||
// CONTENTION WINDOW |
|||
// CWMIN =15 & CWMAX =1023 |
|||
// this means that MAX_BACKOFF IS 6 |
|||
const int MAX_BACKOFF = 6; |
|||
|
|||
//-----------------------------------------------------------------// |
|||
// THE MEDIUM/CHANNEL |
|||
|
|||
// FORMULAE FOR THE CHANNEL |
|||
// channel is busy |
|||
formula busy = c1>0 | c2>0; |
|||
// channel is free |
|||
formula free = c1=0 & c2=0; |
|||
|
|||
module medium |
|||
|
|||
// number of collisions |
|||
col : [0..COL]; |
|||
|
|||
// medium status |
|||
c1 : [0..2]; |
|||
c2 : [0..2]; |
|||
// ci corresponds to messages associated with station i |
|||
// 0 nothing being sent |
|||
// 1 being sent correctly |
|||
// 2 being sent garbled |
|||
|
|||
// begin sending message and nothing else currently being sent |
|||
[send1] c1=0 & c2=0 -> (c1'=1); |
|||
[send2] c2=0 & c1=0 -> (c2'=1); |
|||
|
|||
// begin sending message and something is already being sent |
|||
// in this case both messages become garbled |
|||
[send1] c1=0 & c2>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
|||
[send2] c2=0 & c1>0 -> (c1'=2) & (c2'=2) & (col'=min(col+1,COL)); |
|||
|
|||
// finish sending message |
|||
[finish1] c1>0 -> (c1'=0); |
|||
[finish2] c2>0 -> (c2'=0); |
|||
|
|||
endmodule |
|||
|
|||
//-----------------------------------------------------------------// |
|||
// STATION 1 |
|||
module station1 |
|||
// clock for station 1 |
|||
x1 : [0..TIME_MAX]; |
|||
|
|||
// local state |
|||
s1 : [1..12]; |
|||
// 1 sense |
|||
// 2 wait until free before setting backoff |
|||
// 3 wait for DIFS then set slot |
|||
// 4 set backoff |
|||
// 5 backoff |
|||
// 6 wait until free in backoff |
|||
// 7 wait for DIFS then resume backoff |
|||
// 8 vulnerable |
|||
// 9 transmit |
|||
// 11 wait for SIFS and then ACK |
|||
// 10 wait for ACT_TO |
|||
// 12 done |
|||
// BACKOFF |
|||
// separate into slots |
|||
slot1 : [0..63]; |
|||
backoff1 : [0..15]; |
|||
|
|||
// BACKOFF COUNTER |
|||
bc1 : [0..MAX_BACKOFF]; |
|||
// SENSE |
|||
// let time pass |
|||
[time] s1=1 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// ready to transmit |
|||
[] s1=1 & (x1=DIFS | x1=DIFS-1) -> (s1'=8) & (x1'=0); |
|||
// found channel busy so wait until free |
|||
[] s1=1 & busy -> (s1'=2) & (x1'=0); |
|||
// WAIT UNTIL FREE BEFORE SETTING BACKOFF |
|||
// let time pass (no need for the clock x1 to change) |
|||
[time] s1=2 & busy -> (s1'=2); |
|||
// find that channel is free so check its free for DIFS before setting backoff |
|||
[] s1=2 & free -> (s1'=3); |
|||
// WAIT FOR DIFS THEN SET BACKOFF |
|||
// let time pass |
|||
[time] s1=3 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// found channel busy so wait until free |
|||
[] s1=3 & busy -> (s1'=2) & (x1'=0); |
|||
// start backoff first uniformly choose slot |
|||
// backoff counter 0 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=0 -> (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 1 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=1 -> 1/2 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/2 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 2 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=2 -> 1/4 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/4 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 3 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=3 -> 1/8 : (s1'=4) & (x1'=0) & (slot1'=0) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=1) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=2) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=3) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=4) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=5) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=6) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/8 : (s1'=4) & (x1'=0) & (slot1'=7) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 4 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=4 -> 1/16 : (s1'=4) & (x1'=0) & (slot1'=0 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=1 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=2 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=3 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=4 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=5 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=6 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=7 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=8 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=9 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=10) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=11) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=12) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=13) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=14) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/16 : (s1'=4) & (x1'=0) & (slot1'=15) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// backoff counter 5 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=5 -> 1/32 : (s1'=4) & (x1'=0) & (slot1'=0 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=1 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=2 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=3 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=4 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=5 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=6 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=7 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=8 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=9 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=10) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=11) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=12) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=13) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=14) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=15) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=16) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=17) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=18) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=19) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=20) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=21) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=22) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=23) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=24) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=25) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=26) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=27) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=28) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=29) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=30) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/32 : (s1'=4) & (x1'=0) & (slot1'=31) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
|
|||
// backoff counter 6 |
|||
[] s1=3 & (x1=DIFS | x1=DIFS-1) & bc1=6 -> 1/64 : (s1'=4) & (x1'=0) & (slot1'=0 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=1 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=2 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=3 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=4 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=5 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=6 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=7 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=8 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=9 ) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=10) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=11) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=12) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=13) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=14) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=15) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=16) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=17) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=18) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=19) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=20) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=21) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=22) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=23) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=24) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=25) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=26) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=27) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=28) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=29) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=30) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=31) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=32) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=33) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=34) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=35) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=36) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=37) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=38) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=39) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=40) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=41) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=42) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=43) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=44) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=45) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=46) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=47) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=48) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=49) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=50) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=51) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=52) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=53) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=54) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=55) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=56) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=57) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=58) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=59) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=60) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=61) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=62) & (bc1'=min(bc1+1,MAX_BACKOFF)) |
|||
+ 1/64 : (s1'=4) & (x1'=0) & (slot1'=63) & (bc1'=min(bc1+1,MAX_BACKOFF)); |
|||
// SET BACKOFF (no time can pass) |
|||
// chosen slot now set backoff |
|||
[] s1=4 -> 1/16 : (s1'=5) & (backoff1'=0 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=1 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=2 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=3 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=4 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=5 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=6 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=7 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=8 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=9 ) |
|||
+ 1/16 : (s1'=5) & (backoff1'=10) |
|||
+ 1/16 : (s1'=5) & (backoff1'=11) |
|||
+ 1/16 : (s1'=5) & (backoff1'=12) |
|||
+ 1/16 : (s1'=5) & (backoff1'=13) |
|||
+ 1/16 : (s1'=5) & (backoff1'=14) |
|||
+ 1/16 : (s1'=5) & (backoff1'=15); |
|||
// BACKOFF |
|||
// let time pass |
|||
[time] s1=5 & x1<ASLOTTIME & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// decrement backoff |
|||
[] s1=5 & x1=ASLOTTIME & backoff1>0 -> (s1'=5) & (x1'=0) & (backoff1'=backoff1-1); |
|||
[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1>0 -> (s1'=5) & (x1'=0) & (backoff1'=15) & (slot1'=slot1-1); |
|||
// finish backoff |
|||
[] s1=5 & x1=ASLOTTIME & backoff1=0 & slot1=0 -> (s1'=8) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=5 & busy -> (s1'=6) & (x1'=0); |
|||
// WAIT UNTIL FREE IN BACKOFF |
|||
// let time pass (no need for the clock x1 to change) |
|||
[time] s1=6 & busy -> (s1'=6); |
|||
// find that channel is free |
|||
[] s1=6 & free -> (s1'=7); |
|||
|
|||
// WAIT FOR DIFS THEN RESUME BACKOFF |
|||
// let time pass |
|||
[time] s1=7 & x1<DIFS & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// resume backoff (start again from previous backoff) |
|||
[] s1=7 & (x1=DIFS | x1=DIFS-1) -> (s1'=5) & (x1'=0); |
|||
// found channel busy |
|||
[] s1=7 & busy -> (s1'=6) & (x1'=0); |
|||
|
|||
// VULNERABLE |
|||
// let time pass |
|||
[time] s1=8 & x1<VULN -> (x1'=min(x1+1,TIME_MAX)); |
|||
// move to transmit |
|||
[send1] s1=8 & (x1=VULN | x1=VULN-1) -> (s1'=9) & (x1'=0); |
|||
// TRANSMIT |
|||
// let time pass |
|||
[time] s1=9 & x1<TRANS_TIME_MAX -> (x1'=min(x1+1,TIME_MAX)); |
|||
// finish transmission successful |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=1 -> (s1'=10) & (x1'=0); |
|||
// finish transmission garbled |
|||
[finish1] s1=9 & x1>=TRANS_TIME_MIN & c1=2 -> (s1'=11) & (x1'=0); |
|||
// WAIT FOR SIFS THEN WAIT FOR ACK |
|||
|
|||
// WAIT FOR SIFS i.e. c1=0 |
|||
// check channel and busy: go into backoff |
|||
[] s1=10 & c1=0 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=10 & c1=0 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
// following guard is always false as SIFS=1 |
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// [time] s1=10 & c1=0 & x1>0 & x1<SIFS -> (x1'=min(x1+1,TIME_MAX)); |
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// ack is sent after SIFS (since SIFS-1=0 add condition that channel is free) |
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[send1] s1=10 & c1=0 & (x1=SIFS | (x1=SIFS-1 & free)) -> (s1'=10) & (x1'=0); |
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|
|||
// WAIT FOR ACK i.e. c1=1 |
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// let time pass |
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[time] s1=10 & c1=1 & x1<ACK -> (x1'=min(x1+1,TIME_MAX)); |
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// get acknowledgement so packet sent correctly and move to done |
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[finish1] s1=10 & c1=1 & (x1=ACK | x1=ACK-1) -> (s1'=12) & (x1'=0) & (bc1'=0); |
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|
|||
// WAIT FOR ACK_TO |
|||
// check channel and busy: go into backoff |
|||
[] s1=11 & x1=0 & busy -> (s1'=2); |
|||
// check channel and free: let time pass |
|||
[time] s1=11 & x1=0 & free -> (x1'=min(x1+1,TIME_MAX)); |
|||
// let time pass |
|||
[time] s1=11 & x1>0 & x1<ACK_TO -> (x1'=min(x1+1,TIME_MAX)); |
|||
// no acknowledgement (go to backoff waiting DIFS first) |
|||
[] s1=11 & x1=ACK_TO -> (s1'=3) & (x1'=0); |
|||
|
|||
// DONE |
|||
[time] s1=12 -> (s1'=12); |
|||
endmodule |
|||
|
|||
// ---------------------------------------------------------------------------- // |
|||
// STATION 2 (rename STATION 1) |
|||
module |
|||
station2=station1[x1=x2, |
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s1=s2, |
|||
s2=s1, |
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c1=c2, |
|||
c2=c1, |
|||
slot1=slot2, |
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backoff1=backoff2, |
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bc1=bc2, |
|||
send1=send2, |
|||
finish1=finish2] |
|||
endmodule |
|||
// ---------------------------------------------------------------------------- // |
|||
|
|||
label "twoCollisions" = col=2; |
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label "fourCollisions" = col=4; |
|||
label "sixCollisions" = col=6; |
@ -1 +0,0 @@ |
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P<0.5 [ F oneCollision ] |
@ -0,0 +1 @@ |
|||
P<0.1 [ F fourCollisions ] |
@ -0,0 +1 @@ |
|||
P<0.1 [ F sixCollisions ] |
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