+ T (1) T (1) T (0) T (1) T (0) T (0) T (1) 1 2 3 4 13 14 15 Data In + Data Out 1 T (1) 4 2 (exclusive OR) : +
Media Access Protocol Cycle(240ms) Even Frame (120ms) Odd Frame (120ms) M V Voice M V Voice M V Voice M d Data M V Voice M V Voice M V Voice M d Data Even Frame (120ms) Odd Frame (120ms) M V Voice M V Voice M d Data M d Data M V Voice M V Voice M d Data M d Data
Even Frame (120ms) Odd Frame (120ms) M V M V M V M V M d Data M d Data M d Data M d M d M d Data M d M d M d Data M d Data
1 minute 13.33ms Slot 1 Slot 4500 Current slot Current superframe Slot 4501 Slot 9000 Current superframe + 1
n n+1 A B C D E
Stage 1 : Candidate Candidate Reserved Unreserved Reserved Reserved Unreserved Reserved Reserved Reserved Reserved Stage 2a : Unreserved Available Candidate Reserved Available Reserved Reserved Available Reserved Reserved Reserved Reserved Stage 2b : Available Candidate Reserved Available Reserved Available Available Reserved Reserved Available Reserved Stage 3 : Available Candidate Reserved Unreserved Reserved Reserved Unreserved Reserved Reserved Selected Reserved
3 2 1 OSI LLC MAC
T t-t t t+t
Busy Idle
T Idle Idle
Idle idle
Busy T Idle Idle
DIFS DIFS PIFS DIFS SIFS back-off
CW max 255 255 127 CW min 7 15 31 63
A DIFS CWindow CWindow = back-off back-off B back-off C CWindow D CWindow E CWindow
DIFS PIFS SIFS Medium Busy burst D1 Rx /Tx M1 D2 D2 D2 CCAdel CCAdel CCAdel M2 M2 M2 Rx /Tx Rx /Tx Rx /Tx D1 = arxrfdelay + arxplcpdelay RxTx = arxtxturnaround Time CCAdel = accaassessment Time D2 = D1 + Air Propagation Time M1 = M2 = amacpredelay
PIFS SIFS SIFS SIFS SIFS SIFS PIFS SIFS SIFS D1+poll U1+ack D2+ack+poll U2+ack D3+ack+poll D4+poll U4+ack CF-End D = PC U = PC
B0 To DS From DS More Pwr Retry Frag Mgt More Data WEP Order B15 Pwr 0 0 0 0 Mgt 0 0 0 : 2 2 4 1 1 1 1 1 1 1 1 Octets: 2 2 6 6 4 RA TA CRC
Octets: 2 2 6 4 RA CRC Octets: 2 2 6 4 RA CRC
DIFS (200bytes)
DIFS (200bytes) SIFS ACK (15bytes)
DIFS RTS (20bytes) SIFS CTS SIFS (200bytes) SIFS ACK (15bytes) (15bytes)
1 2
1 2
G3 G2 G1 G1 G2 G1 G1 G1 Source CW RTS DATA Access Point CTS ACK RTS DATA Destination CTS ACK Other NAV(RTS) NAV(CTS) NAV(DATA) NAV(RTS) NAV(CTS) NAV(DATA) G1 : SIFS G2 : PIFS G3 : DIFS
Pn(x) 0 CW Pn(x) 0 CW Pn(x) 0 CW
1 3 2 0 64 128 255
1 1/8 1 1 0 CW = 0 CW = 1 CW = 2 1/8 1/8 1/8 1 CW = 7
(1-p)/W 0 p/w p/w 0 0 1 1 1 0,0 0,1 0,2 0,W 0-2 0, W 0-1 p/w 1 i-1,0 p/w p/w i i 1 1 1 i,0 i,1 i,2 i,w i -2 i, W i -1 p/w i+1 p/w p/w m m 1 1 1 m,0 m,1 m,2 m,w m -2 m,w m -1 p/w m p/w m
슬롯타임에전송된유효정보슬롯타임의길이
1.0 0.9 0.8 ACSMA/CA-TypeI(Simulation) ACSMA/CA-TypeI(Analysis) 0.7 S(Throughput) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
0.6 0.5 S(Throughput) 0.4 0.3 0.2 ACSMA/CA-TypeI 4-Way CSMA/CA 0.1 0.0 10-1 10 0 10 1 10 2 G(Offered Load) 20 18 D(Average Delay)(sec) 16 14 12 10 8 6 4 ACSMA/CA-TypeI 4-Way CSMA/CA 2 0 10 0 10 1 10 2 G(Offered Load)
0.6 Transmission Prob.= 0.9:0.1 Transmission Prob.= 0.8:0.2 Transmission Prob.= 0.7:0.3 Transmission Prob.= 0.6:0.4 Transmission Prob.= 0.5:0.5 0.5 S(Throughput) 0.4 0.3 0.2 0.1 10-1 10 0 10 1 10 2 G(Offered Load)
3.4 3.2 3.0 2.8 2.6 Number of Try 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 10-1 10 0 10 1 10 2 G(Offered Load) Transmission Prob.= 0.9:0.1 Transmission Prob.= 0.8:0.2 Transmission Prob.= 0.7:0.3 Transmission Prob.= 0.6:0.4 Transmission Prob.= 0.5:0.5
D(Average Delay)(sec) 20 18 16 14 12 10 8 6 4 2 Transmission Prob.= 0.9:0.1 Transmission Prob.= 0.8:0.2 Transmission Prob.= 0.7:0.3 Transmission Prob.= 0.6:0.4 Transmission Prob.= 0.5:0.5 0 10-1 10 0 10 1 10 2 G(Offered Load)
1200 1000 Attempt Numbers 800 600 400 200 0 0 50 100 CW(Contention Window) Value
200 150 Attempt Numbers 100 50 0 0 50 100 CW(Contention Window) Value
1.0 0.9 0.8 ACSMA/CA-TypeII(Simulation) ACSMA/CA-TypeII(Analysis) 0.7 S(Throughput) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
0.8 Pure ALOHA non-persistent CSMA CSMA/CD ACSMA/CA-TypeII 0.6 S(Throughput) 0.4 0.2 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
300 D(Average Delay)(sec) 250 200 150 100 50 ACSMA/CA-TypeII 2-Way CSMA/CA non-persistent CSMA 0 1E-3 0.01 0.1 1 10 100 G(Offered Load)
S(Throughput) 0.8 ACSMA/CA-TypeII Basic access mechanism 2-Way access mechanism 0.7 4-Way access mechanism 0.6 0.5 0.4 0.3 0.2 0.1 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
35 D(Average Delay)(sec) 30 25 20 15 10 ACSMA/CA-TypeII Basic access mechanism 2-Way access mechanism 4-Way access mechanism 5 0 10-1 10 0 10 1 10 2 G(Offered Load)
0.9 0.8 0.7 S(Throughput) 0.6 0.5 0.4 0.3 0.2 0.1 100 Bytes 200 Bytes 400 Bytes 600 Bytes 0.0 10-1 10 0 10 1 10 2 G(Offered Load) D(Average Delay)(sec) 60 50 40 30 20 10 100 Bytes 200 Bytes 400 Bytes 600 Bytes 0 10-1 10 0 10 1 10 2 G(Offered Load)
0.8 0.7 0.6 S(Throughput) 0.5 0.4 0.3 0.2 0.1 0.6ms 1.2ms 2.4ms 4.8ms 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
D(Average Delay)(sec) 40 35 30 25 20 15 10 5 0.6ms 1.2ms 2.4ms 4.8ms 0 10-1 10 0 10 1 10 2 G(Offered Load)
0.8 0.7 0.6 S(Throughput) 0.5 0.4 0.3 0.2 0.1 200 stations 300 stations 400 stations 500 stations 600 stations 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
D(Average Delay)(sec) 50 45 40 35 30 25 20 15 10 5 200 stations 300 stations 400 stations 500 stations 600 stations 0 10-1 10 0 10 1 10 2 G(Offered Load)
50 D(Average Delay)(sec) 40 30 20 10 200 stations 300 stations 400 stations 500 stations 600 stations 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 S(Throughput)
1200 1000 Attempt Numbers 800 600 400 200 0 50 100 150 200 250 CW(Contention Window) Value 1.0 0.9 0.8 ACSMA/CA-TypeIII(Simulation) ACSMA/CA-TypeIII(Analysis) 0.7 S(Throughput) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
0.8 0.6 Pure ALOHA non-persistent CSMA CSMA/CD 2-Way CSMA/CA ACSMA/CA-TypeIII S(Throughput) 0.4 0.2 0.0 10-1 10 0 10 1 10 2 G(Offered Load)
200 D(Average Delay)(sec) 150 100 50 ACSMA/CA-TypeIII 2-Way CSMA/CA non-persistent CSMA 0 10-1 10 0 10 1 10 2 G(Offered Load)
200 D(Average Delay)(sec) 150 100 50 ACSMA/CA-TypeIII 2-Way CSMA/CA non-persistent CSMA 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 S(Throughput)
25 20 D(Average Delay)(sec) 15 10 5 ACSMA/CA-TypeIII - 1st Priority ACSMA/CA-TypeIII - 2nd Priority ACSMA/CA-TypeIII - 3rd Priority 0 10-1 10 0 10 1 G(Offered Load)