1 Performance de la couche d’acc`es CSMA/CA RTS/CTS. . . 2 2 CSMA/CA Basique [9] . . . 3 3 CSMA/CA - RTS/CTS [9] . . . 4 4 Mod`ele de Bianchi pour l’analyse du CSMA/CA [10]. . . 6 5 Exemple de sc´enario pour le M CSMA/CA - RTS/CTS . . . 8 6 Erreur (%) entre le mod`ele analytique et la simulation. . . 10 7 M-CSMA/CA ordonnance avec une taille d’ordonnanceur de 2 . . . 11 8 Les performances des m´ethodes d’acc`es `a contention. . . 12 9 Synth`ese du CSMA/CA – RTS/CTS pour le cas des r´eseaux charg´es. . . 13 10 Synth`ese du CSMA/CA – RTS/CTS pour le cas des r´eseaux non charg´es. . . . 14 11 Sous porteuses WiFi pour le mode ”legacy” [14]. . . 14 12 Interf´erence entre les bandes. . . 15 13 Cas du M-CSMA/CA-RTS/CTS avec 2 sous bandes. . . 15 14 Messages d’RTS asynchrones. . . 17 15 D´ebit en mode satur´e en Mbps en fonction du nombre des nœuds en pr´esence
de l’interf´erence inter bande pour diff´erentes valeurs d’intervalle de garde avec un canal AWGN. . . 19 16 D´ebit en mode satur´e en Mbps en fonction du nombre des nœuds en pr´esence
de l’interf´erence inter bande pour diff´erentes valeurs d’intervalle de garde avec un canal D. . . 20 1.1 Use case categories definition [1] . . . 1 1.2 Contention based MAC performance . . . 2 2.1 OSI model [16] . . . 7 2.2 Multiplexing/Demultiplexing process . . . 8 2.3 Deterministic access techniques [17] . . . 8 2.4 Random access protocols [18] . . . 9 2.5 ALOHA [18] . . . 10 2.6 Slotted ALOHA [18] . . . 10 2.7 CSMA Modes [18] . . . 11 2.8 CSMA/CD Scheme [19] . . . 12 2.9 CSMA/CA’s three strategies [18] . . . 12 2.10 Basic CSMA/CA Algorithm [9] . . . 13 2.11 CSMA/CA - RTS/CTS Algorithm [9] . . . 13 2.12 Markov Chain model for the backoff window size. . . 15 2.13 Saturation throughput comparision between basic and RTS/CTS CSMA/CA [9]. 17 2.14 802.11 and proposed backoff strategy. . . 18 2.15 Markov chain model of backoff window size in proposed CSMA/CA. . . 19 2.16 Relative error vs. number of mobile stations. . . 21 2.17 Saturation throughput for proposed strategy with RTS/CTS transmission. . . 21 2.18 Saturation throughput for classical 802.11 with RTS/CTS transmission. . . 22
2.19 CDF of access delay for m = 3 with 50 mobile stations. Delay is expressed in second. . . 23 2.20 CSMA/ECA description [20] . . . 24 3.1 Single channel CSMA/CA - RTS/CTS time repartition vs. number of mobile
stations. . . 28 3.2 Multi channel CSMA/CA - RTS/CTS. . . 29 3.3 Illustration of the hidden and exposed node problem . . . 31 3.4 Backoff model for the proposed CSMA/CA with infinite retry limit. Compared
to Bianchi [9], the probability is pi instead of p. . . 34
3.5 Backoff model for the proposed CSMA/CA with finite retry limit. . . 36 3.6 Saturation throughput for 2 RTS sub-channels based on the analytical model. 39 3.7 Saturation throughput for 2 RTS sub-channels based on simulation. . . 39 3.8 Error (%) between analytical model and simulation. . . 40 3.9 Collision probability gain vs. number of mobile stations for various number of
RTS sub-channels. . . 41 3.10 CSMA/CA - RTS/CTS time repartition vs. number of mobile stations for 3
RTS sub-bands. . . 42 3.11 CSMA/CA - RTS/CTS time repartition vs. number of mobile stations for 5
RTS sub-bands. . . 43 3.12 Saturation throughput vs. number of mobile stations for various number of
RTS sub-channels. . . 44 3.13 Saturation throughput (bits/sec) vs. number of mobile stations for various
number of RTS sub-channels with m=r=3. . . 44 3.14 Saturation throughput gain vs. number of mobile stations for various number
of RTS sub-channels. . . 45 3.15 Transmission delay gain vs. number of mobile stations for various number of
RTS sub-channels. . . 46 3.16 Packet drop probability for single channel vs. number of backoff stages for
various retransmission limits. . . 46 3.17 Packet drop probability for #sub-channels=2 vs. number of backoff stages for
various retransmission limits. . . 47 3.18 Packet drop probability for #sub-channels=3 vs. number of backoff stages for
various retransmission limits. . . 47 3.19 Contention Based MAC Performance. . . 48 3.20 Saturation throughput difference (%) between Pre and Postallocation tech-
niques vs. the number of mobile station for various number of sub-channels. . 50 4.1 Flow chart of the proposed strategy. . . 52 4.2 Flow chart of the proposed strategy. . . 53 4.3 Scheduled multiband CSMA/CA with RTS/CTS mechanism with scheduler
size=2. . . 54 4.4 CTS frame format. . . 54 4.5 CSMA/CA - RTS/CTS time repartition vs. number of mobile stations for 5
RTS sub-bands with scheduler size=3. . . 54 4.6 Saturation Throughput Gain (%) vs. number of nodes for scheduler size=1. . . 55 4.7 Saturation Throughput Gain (%) vs. number of nodes for scheduler size=2. . . 56 4.8 Saturation Throughput Gain (%) vs. number of nodes for scheduler size=3. . . 57 4.9 Saturation Throughput Gain (%) vs. number of nodes for scheduler size=1. . . 57 4.10 Saturation Throughput Gain (%) vs. number of nodes for scheduler size=2. . . 58 4.11 Saturation Throughput Gain (%) vs. number of nodes for scheduler size=3. . . 58 4.12 Delay Gain (%) vs. number of nodes for various number of sub-bands with
4.13 Delay Gain (%) vs. number of nodes for various number of sub-bands with scheduler size=2. . . 59 4.14 Delay Gain (%) vs. number of nodes for various number of sub-bands with
scheduler size=3. . . 60 4.15 Packet Drop Probability for scheduler size=1. . . 60 4.16 Packet Drop Probability for scheduler size=2. . . 61 4.17 Packet Drop Probability for scheduler size=3. . . 61 4.18 Contention Based MAC Performance. . . 62 4.19 CSMA/CA - RTS/CTS synthesis for loaded scenario. . . 63 4.20 CSMA/CA - RTS/CTS synthesis for unloaded scenario. . . 64 5.1 80211n WLAN frame, Legacy Mode [21]. . . 66 5.2 WLAN frame modifications to allow for MIMO operation, Mixed Mode [21]. . 66 5.3 802.11n WLAN frame, Green Field [21]. . . 66 5.4 Legacy Signal Field (L-SIG) [22]. . . 67 5.5 WiFi subcarriers according to legacy mode [14]. . . 67 5.6 Block diagram of the transmitter. . . 68 5.7 Interband Interference. . . 71 5.8 Architecture of OFDM transmitter. . . 71 5.9 Architecture of OFDM receiver. . . 72 5.10 Architecture of single band TX-RX. . . 72 5.11 Architecture of M-CSMA/CA-RTS/CTS TX-RX with n RTS sub-bands. . . . 75 5.12 Block diagram of M-CSMA/CA-RTS/CTS TX-RX with 2 RTS sub-bands. . . 75 5.13 Developped M-CSMA/CA-RTS/CTS with 2 sub-bands architecture. . . 76 5.14 Asynchronous RTS messages. . . 77 5.15 Interference matrices . . . 79 5.16 Synchronous RTS messages. . . 80 5.17 Quasi synchronous RTS messages. . . 80 5.18 SIR (dB) vs. d. . . 81 5.19 Leakage (dB) vs. d. . . 82 5.20 Application scenario. . . 83 5.21 Saturation throughput in Mbits/s for various number of users and for all MCS
index with GI=8. . . 84 5.22 Saturation throughput in Mbits/s for various number of users and for all MCS
index with GI=16. . . 85 5.23 Captured saturation throughput in Mbits/s for various number of users and for
all MCS index with GI=8 and Th=3.5dB. . . 86 5.24 Captured saturation throughput in Mbits/s for various number of users and for
all MCS index with GI=16 and Th=3.5dB. . . 87 5.25 Captured saturation throughput in Mbits/s for various number of users and for
all MCS index with GI=8 and Th=5.5dB for AWGN channel. . . 87 5.26 Captured saturation throughput in Mbits/s for various number of users and for
all MCS index with GI=16 and Th=5.5dB for AWGN channel. . . 88 5.27 Captured saturation throughput in Mbits/s for various number of users and for
all MCS index with GI=8 and Th=11.5dB for D fading channel. . . 89 5.28 Captured achievable throughput in Mbits/s for various number of users and for
all MCS index with GI=16 and Th=11.5dB for D fading channel. . . 89 5.29 Captured saturation throughput in Mbits/s for various number of users and for
all MCS index with GI=8 and Th=13.5db. . . 90 5.30 Captured saturation throughput in Mbits/s for various number of users and for
5.31 STR for AWGN Channel with circular map of radius = 300m, x and y axis presents the cartesian coordinates. . . 91 5.32 STR for D Fading Channel with circular map of radius = 300m, x and y axis
presents the cartesian coordinates. . . 91 5.33 Saturation throughput in Mbits/s vs. number of users for all MCS index con-
sidering interband interference with different guard interval for AWGN channel. 92 5.34 Saturation throughput in Mbits/s vs. number of users for all MCS index con-