1. Introducere: plotting
2. Introducere: ns-3: structura, build, rulat exemple cu plot si pcap tracing (wifi-tcp?)
3. Capacitatea mediului WiFi - cea ideala
4. Capacitatea mediului WiFi - downlink vs uplink
5. Modele de propagare WiFi: Friis, LogDistancePropagationLossModel, ThreeLogDistancePropagationLossModel , TwoRayGroundPropagationLossModel cu trafic UDP vs. TCP si cu/fara RTS/CTS
6. Carrier sense fizic (EnergyDetectionThreshold) vs virtual (RX sensitivity)
7. DCF / contention window
8. DCF / contention window (cont.)
9. Jain Fairness
10. MCS multiple si rate adaption cu distanta (e unul din exemplele din ns-3)
11. WiFi in Linux: setup hostapd, wpa_supplicant, iw, modul monitor si tcpdump - analizat radio tap header
12. WiFi in Linux 2: monitorizare PHY cu USRP?

//Din documentatia ns-3: https://www.nsnam.org/doxygen/classns3_1_1_wifi_mac.html
//https://www.nsnam.org/docs/release/3.5/manual/manual_59.html
//https://mehmetalierturk.com/2014/01/07/how-to-set-edca-parameters-in-ns3-802-11/
 
void ns3::WifiMac::ConfigureDcf	(	Ptr< Txop > 	dcf,
uint32_t 	cwmin,
uint32_t 	cwmax,
bool 	isDsss,
AcIndex 	ac 
)
 
NqosWifiMacHelper wifiMacHelper = NqosWifiMacHelper::Default ();
  Ssid ssid = Ssid ("ns-3-ssid");
  wifiMacHelper.SetType ("ns3::NqstaWifiMac", "Ssid", SsidValue (ssid), "ActiveProbing", BooleanValue (false));
  wifiMacHelper.SetDcaParameters ("MinCw", UintegerValue (20), "Aifsn", UintegerValue (3));

Un laborator in care capturam in modul monitor o asociere cu criptare WPA2 si o asociere in plain text. Setup-ul ar fi: AP → STA (Linux PC) + un alt PC cu iw monitor mode pornit. Scopul este:

• Analiza pachetelor de tip 802.11 ca aici: https://www.youtube.com/watch?v=ZXD_qg5dddM ; https://www.youtube.com/watch?v=Kn4hVq5vI3E
• Sa vada ca in beacon se face advertising la capabilitatile routerului (protocoale suportate, MCS-uri etc. - vezi asta: http://www.sharetechnote.com/html/WLAN_Beacon.html ) si ca in probe request STA isi declara capabilitatile
• Sa observe ca tot ce inseamna frame-uri de management (probe request, probe response assoc request blabla) se fac in format legacy la cel mai mic MCS suportat de AP si STA - motivele sunt evidente - nu vrem deloc sa pierdem/ratam aceste cadre
• Sa observe ca field-ul duration din beacone e 0 - beaconul folosește broadcast (fără SIFS+ACK)
• Sa vada ACK-urile de nivel wifi pentru fiecare cadru de management
• Sa analize duration-ul din pachete si sa observe ca e DIFS+SIFS+durata pachetului la cea mai mica modulatie
• Sa folosim cablu RF si 2 atenuatuare si sa observe scaderea SSI-ul sau antena si sa deplasam obiectele si sa observe scaderea SSI-ul si rate adaptionul de la MCS-uri
• FUN: configurat AP-ul sa foloseasca WEP encryption si sa foloseasca aircrack-ng

Curs echivalent: Pozele de aici: http://www.sharetechnote.com/html/WLAN_FrameStructure.html + poza asta: http://www.sharetechnote.com/image/WLAN_Stack_Overview.png

Folosire hwsim de mac80211 sa se joace cu drivere? https://w1.fi/cgit/hostap/plain/tests/hwsim/example-setup.txt

Review TCP: CW, AW, RTT, fast retr, throughput

• One hop wireless: AP→client
• plot MAC loss/delay/jitter vs PHY loss for fixed situations
  • uniform loses
  • bursty losses
  • fixed rate, retries
• TCP/ICMP RTT vs MAC loss
• Application level RTT vs MAC loss
• Application level RTT vs AP bufferbloat

• Topology with one hop WiFi and one hop wired: simplest practical WiFi.
• download S→AP→Client
  • vary loss on the wireless link
  • vary delay on the wired link
  • vary buffer in the AP
  • monitor CW, RTT, throughput

• what is in which OS? Linux/Windows/IOS
• SACK, TCP flavors

• increased efficiency?
• TCP acks are uplink - is there a problem?
• good link vs bad link, HOL blocking, fairness