Session 2. Wireless LAN in ns-3. 윤강진 Multimedia & Wireless Networking Laboratory, SNU

Transcription

1 Session 2. Wireless LAN in ns-3 윤강진 Multimedia & Wireless Networking Laboratory, SNU 1

2 Contents IEEE Wireless LAN WLAN Basic Operation in ns-3 Exercise 2

3 IEEE Wireless LAN 3

4 IEEE Wireless LAN Popular for enterprise, home, hot-spot Enables (indoor) wireless and mobile high-speed networking Wireless Ethernet with comparable speed Supports up to 600 Mbps within ~100 m range Runs at unlicensed bands at 2.4 GHz and 5 GHz Emerging extensions operate at 50~700 MHz (TV white space), 900 MHz, 3.65 GHz (Satellite band), 60 GHz, etc. MAC and PHY layer technology 4

5 IEEE Standard Overview Layers 1 and 2 Layer One MAC and multiple PHYs 7 Application MAC 4 TCP 2.4 GHz 2.4 GHz DS FH IR 5 GHz.11a OFDM 3 IP LLC b CCK.11g OFDM In 1999 In 2003 In & 5 GHz 1 MAC PHY n OFDM 5 GHz.11ac OFDM In 2009 In

6 IEEE Architecture Internet Infrastructure mode Infrastructure Basic Service Set BSS An access point (AP) and multiple stations (STAs) Every transmission is with AP; no peer-to-peer communication BSS 1 AP hub, switch or router AP Ad hoc mode Independent Basic Service Set IBSS Multiple stations (STAs), and no AP Peer-to-peer communication only BSS 2 6

7 Layer Interactions Datagram vs. LPDU vs. MPDU (MAC frame) vs. PPDU (PHY frame) Datagram IP Datagram octets: 3 5 Variable LPDU LLC Header SNAP Header LSDU octets: 26 Variable 4 MPDU MAC Header MSDU FCS PPDU PLCP Preamble PLCP Header PSDU 7

8 IEEE Frame Format duration of reserved transmission time (RTS/CTS) frame seq # frame control duration address 1 address 2 address 3 seq control address 4 payload CRC Protocol version Type Subtype To AP From AP More frag Retry Power mgt More data WEP Rsvd frame type (RTS, CTS, ACK, data) 8

9 Overview of WiFi Model in ns-3 ns-3 provides models for WifiNetDevice models a wireless network interface ns-3 supports basic DCF with infrastructure and ad hoc modes a, b and g physical layers QoS-based EDCA and queueing extensions of e various propagation loss models including Nakagami, Rayleigh, Friis, LogDistance, FixedRss, Random various rate control algorithms including Aarf, Arf, Cara, Onoe, Rraa, ConstantRate, and Minstrel s (mesh) 9

10 Overview of WiFi Model Four levels of models PHY layer model ns3::wifiphy MAC low models ns3::maclow Takes care of RTS/CTS/DATA/ACK transmission ns3::dcfmanager, ns3::dcfstate Implements DCF and EDCAF function ns3::dcatxop, ns3::edcatxopn Handles packet queue, packet fragmentation, retransmission MAC high models ns3::regularwifimac ns3::apwifimac, ns3::stawifimac, ns3::adhocwifimac Rate control algorithms ns3::wifiremotestationmanager 10

11 Overview of WiFi Model 11

12 WiFi Transmission Flow 12

13 WLAN Basic Operation in ns-3 13

14 Inclass Assignment 1 1. Create Nodes: NodeContainer 2. Create PHY: YansWifiPhyHelper 3. Create MAC: HtWifiMacHelper 4. WLAN Setting: WifiHelper 5. Create NetDevices: NetDeviceContainer 6. Create Network Layer: InternetStackHelper 7. Locate Nodes: MobilityHelper 8. Create UDP Application: UdpServerHelper, UdpClientHelper 9. Simulation Run and Calc. Throughput 14

15 Inclass Assignment 1 8. APP 8. UDP 6. IP 1. Node 5. NetDevice 4. WLAN Setting 2. PHY 3. MAC 7. Location 15

16 1. Create Nodes Create two NodeContainers: wifistanode, wifiapnode Let s make 1 STA and 1 AP 16

17 Create channel 2. Create PHY Layer 17

18 Create PHY Set channel to PHY 2. Create PHY Layer 18

19 Create MAC Create SSID 3. Create MAC Layer Set MAC (type= ns3::stawifimac ) Set attribute Ssid to SsidValue(...) Set attribute ActiveProbing to BooleanValue (false) 19

20 4. WLAN Setting Set Standard 20

21 4. WLAN Setting Set TX rate (type= ns3::constantratewifimanager ) Set attribute DataMode to StringValue (...) Set attribute ControlMode to StringValue (...) 11n MCSs: HtMcs7 ~ HtMcs0 21

22 5. Create NetDevices Create NetDevice for STA Install WLAN (setting, PHY, MAC, wifistanode) to STA NetDevice 22

23 5. Create NetDevices Change MAC type and setting (type= ns3::apwifimac ) Set attribute Ssid to SsidValue(...) Set attribute BeaconInterval to TimeValue (MicroSeconds (102400)) Set attribute BeaconGeneration to BooleanValue (true) Create NetDevice for AP Install WLAN (setting, PHY, MAC, wifiapnode) to AP NetDevice 23

24 6. Create Network Layer Create InternetStack Install wifiapnode and wifistanode to InternetStack 24

25 6. Create Network Layer Create Ipv4 address Set network, mask, and base address 25

26 6. Create Network Layer Create Ipv4InterfaceContainer (for STA and AP) Assign Ipv4 address to NetDevices (for STA and AP) 26

27 7. Locate Nodes Create MobilityHelper Create pointer of ListPositionAllocator Add new Vectors to ListPositionAllocator (for AP and STA) Vector (0.0, 0.0, 0.0) for AP, Vector (1.0, 0.0, 0.0) for STA 27

28 7. Locate Nodes Set ListPositionAllocator to MobilityHelper Set type of mobilitymodel to MobilityHelper Set to ns3::constantpositionmobilitymodel 28

29 7. Locate Nodes Install nodes to MobilityHelper 29

30 8. Create UDP Application Create UDP server Create server application on server node 30

31 8. Create UDP Application Start and stop server application on server node Start server app at Seconds(0.0) Stop server app at Seconds(simulationTime +1) 31

32 8. Create UDP Application Create UDP client 32

33 8. Create UDP Application Set UDP client attributes Set MaxPackets to (=2^32-1) Set Interval to TimeValue (Time ( )) Set PacketSize to UintegerValue (payloadsize) 33

34 8. Create UDP Application Create client application on server node Start and stop server application on server node Start server app at Seconds(1.0) Stop server app at Seconds(simulationTime +1) 34

35 9. Simulation Run and Calc. Thpt. Run simulation Schedule simulation stop time Destroy simulation 35

36 9. Simulation Run and Calc. Thpt. Throughput calculation Get # of total received packets at UDP server Calculate throughput (Mbps) Thpt = totalpacketsrecv * payloadsize * 8 / (simulationtime *10^6) Screen out the result std::cout << Throughput= << Thpt << Mbps << \n ; 36

37 Exercise 1. Make command line arguments for packet size, simulation time (and TX rate) 2. Change TX rate and packet size and observe throughput change. And think about why. 37

38 Q & A 38