Example Solutions

Example 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

A

B

C

t =0

DIFS =2

Random backoff = rA = 0

Random backoff = rC = 1

Packet length = 10

DIFS =2

SIFS=1

ACK=1

DIFS =2

Frozen Random backoff = rC = 1

Random backoff decremented, rC = 0

Packet length = 5

SIFS=1

ACK=1

Answer: T = 24

Example 2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

A

B

C

t =0

DIFS =2

Random backoff = rA = 1

Random backoff = rC = 1

Packet length = 10

DIFS =2

SIFS=1

ACK=1

DIFS =2 Packet length = 5

SIFS=1

ACK=1

Packet length = 5

Packet collision

Packet collision

DIFS =2

New Random backoff = rA = 0

New Random backoff = rC = 1

Packet length = 10

DIFS =2

Frozen Random backoff = rC = 1 Random backoff decremented, rC = 0

Answer: T = 37