Classical Performance models ① Poisson offered load g traffic Se erved -persistent packets CSMA/CD 只O∽0=0 collided B不KB packets ② ③ Poisson
Classical Performance Models retransmission offered load G LAN traffic Served packets BEB collided packets 1-persistent CSMA/CD Poisson Poisson
Example 2: IEEE 802.11 The IEEE 802.11 MAC protocol: (1) Carrier Sensed Multiple Access with Collision Avoidance(CSMA/CA) (2)The Binary Exponential Backoff (BEB) Algorithm
Example 2: IEEE 802.11 The IEEE 802.11 MAC protocol: (1) Carrier Sensed Multiple Access with Collision Avoidance (CSMA/CA) (2) The Binary Exponential Backoff (BEB) Algorithm
channel is busy idle slots Data ACK idle slots time DIFS SIFS DIFS idle RTS CTS Data ACK idle slots slots time DIFS SIFS SIFS SIFS DIFS Figure 1: The IEEE 802. 11 access methods: (a) Basic access method (b)Four-way handshaking access method
Figure 1: The IEEE 802.11 access methods: (a) Basic access method. (b) Four-way handshaking access method Data ACK DIFS SIFS DIFS idle slots channel is busy idle slots (a) time DIFS SIFS SIFS SIFS DIFS idle slots idle slots RTS CTS Data ACK (b) time
Detailed Analysis LAN traffic Served CSMA/CA packets BEB collided packets IEEE802.11
Detailed Analysis CSMA/CA BEB collided packets LAN traffic Served packets IEEE 802.11