ns3 Training Advanced Wireless ns3 training June 2016

ns-3 Training Advanced Wireless ns-3 training, June 2016 1

Outline • Wi-Fi in detail – Support of standard features – Architecture – Configuration via helpers • Advanced use case: LAA-Wifi-Coexistence – Spectrum. Wifi. Phy – Adding a LBT Access Manager – Scenario support – Output data processing ns-3 training, June 2016 2

Wi-Fi Overview • Wi. Fi module features – – – – DCF implementation (Basic + RTS/CTS) 802. 11 a/b/g/n/ac (2. 4 & 5 GHz) PHY MSDU/MPDU aggregation Qo. S support (EDCA) Infrastructure and ad-hoc modes Many rate adaptation algorithms AWGN-based error models • Unsupported features – MIMO – 11 ac advanced features (Tx beamforming, Mu-MIMO) • Related modules – Mesh (802. 11 s) and WAVE (802. 11 p/vehicular) ns-3 training, June 2016 3

Wi-Fi Architecture ns-3 training, June 2016 4

MAC High • Presently, three MAC high models – Adhoc. Wifi. Mac: simplest one – Ap. Wifi. Mac: beacon, associations by STAs – Sta. Wifi. Mac: association based on beacons • All inherit from Regular. Wifi. Mac, which handles Qo. S and non-Qo. S support ns-3 training, June 2016 5

Rate controls The following rate control algorithms can be used by the MAC low layer: • Algorithms found in real devices: – Arf. Wifi. Manager (default for Wifi. Helper), Onoe. Wifi. Manager, Constant. Rate. Wifi. Manager, Minstrel. Ht. Wifi. Manager • Algorithms in literature: – Ideal. Wifi. Manager, Aarf. Wifi. Manager, Amrr. Wifi. Manager, Cara. Wifi. Manager, Rraa. Wifi. Manager, Aarfcd. Wifi. Manager, Parf. Wifi. Manager, Aparf. Wifi. Manager • Example use of constant rate std: : string phy. Mode ("Ofdm. Rate 54 Mbps"); wifi. Set. Remote. Station. Manager ("ns 3: : Constant. Rate. Wifi. Manager", "Data. Mode", String. Value (phy. Mode), "Control. Mode", String. Value (phy. Mode)); ns-3 training, June 2016 6

MAC Middle/Low Three components: • Mac. Low – RTS/CTS/DATA/ACK transactions – Aggregation, Block acks • Dcf. Manager – implements the DCF • Dca. Txop and Edca. Txop. N: – One for NQo. S, the other for Qo. S – Packet queue – Fragmentation/Retransmissions ns-3 training, June 2016 7

Current Wi-Fi PHY abstraction ns-3 training, June 2016 8

Physical layer • No AGC model • Sync on first RX with energy > detection threshold • Collision: the error model will likely cause a drop of the packet • No capture effect: won’t re-sync on a stronger packet ns-3 training, June 2016 9

Error models • Based on analytical models with error bounds • Three implementations with different bounds: Yans. Error. Rate. Model, Nist. Error. Rate. Model, Dss. Error. Rate. Model Nist. Error. Rate. Model (OFDM) Dsss. Error. Rate. Model ns-3 training, June 2016 10

Interference helper • SINR evaluated on chunk-by-chunk basis ns-3 training, June 2016 11

Configuring 802. 11 n/ac • Example programs include – examples/wireless/ht-wifi-network. cc – examples/wireless/vht-wifi-network. cc – examples/wireless/wifi-aggregation. cc • Setting the Wifi. Phy. Standard will set most defaults reasonably Wifi. Helper wifi; wifi. Set. Standard (WIFI_PHY_STANDARD_80211 ac); Wifi. Mac. Helper mac; • 802. 11 ac uses 80 MHz channel by default; 802. 11 n uses 20 MHz ns-3 training, June 2016 12

802. 11 n/ac rate controls • Possible options are Ideal. Wifi. Manager, Minstrel. Ht. Wifi. Manager, and Constant. Rate. Wifi. Manager • examples: – src/wifi/examples/ideal-wifi-managerexample. cc – src/wifi/examples/minstrel-ht-wifi-managerexample. cc ns-3 training, June 2016 13

Example output for Minstrel. Ht $. /waf --run "minstrel-ht-wifi-manager-example --standard=802. 11 n-5 GHz" $ gnuplot minstrel-ht-802. 11 n-5 GHz-20 MHz-LGI-1 SS. plt ns-3 training, June 2016 14

Typical configuration std: : string phy. Mode ("Dsss. Rate 1 Mbps"); Node. Container ap; ap. Create (1); Node. Container sta; sta. Create (2); Wifi. Helper wifi; wifi. Set. Standard (WIFI_PHY_STANDARD_80211 b); Yans. Wifi. Phy. Helper wifi. Phy = Yans. Wifi. Phy. Helper: : Default (); // ns-3 supports Radio. Tap and Prism tracing extensions for 802. 11 wifi. Phy. Set. Pcap. Data. Link. Type (Yans. Wifi. Phy. Helper: : DLT_IEEE 802_11_RADIO); Yans. Wifi. Channel. Helper wifi. Channel; // reference loss must be changed since 802. 11 b is operating at 2. 4 GHz wifi. Channel. Set. Propagation. Delay ("ns 3: : Constant. Speed. Propagation. Delay. Model"); wifi. Channel. Add. Propagation. Loss ("ns 3: : Log. Distance. Propagation. Loss. Model", "Exponent", Double. Value (3. 0), "Reference. Loss", Double. Value (40. 0459)); wifi. Phy. Set. Channel (wifi. Channel. Create ()); ns-3 training, June 2016 15

Typical configuration (cont. ) // Add a non-Qo. S upper mac, and disable rate control Wifi. Mac. Helper wifi. Mac; wifi. Set. Remote. Station. Manager ("ns 3: : Constant. Rate. Wifi. Manager", "Data. Mode", String. Value (phy. Mode), "Control. Mode", String. Value (phy. Mode)); // Setup the rest of the upper mac Ssid ssid = Ssid ("wifi-default"); // setup ap. wifi. Mac. Set. Type ("ns 3: : Ap. Wifi. Mac", "Ssid", Ssid. Value (ssid)); Net. Device. Container ap. Device = wifi. Install (wifi. Phy, wifi. Mac, ap); Net. Device. Container devices = ap. Device; // setup sta. wifi. Mac. Set. Type ("ns 3: : Sta. Wifi. Mac", "Ssid", Ssid. Value (ssid), "Active. Probing", Boolean. Value (false)); Net. Device. Container sta. Device = wifi. Install (wifi. Phy, wifi. Mac, sta); devices. Add (sta. Device); ns-3 training, June 2016 16

Typical configuration (cont. ) // Configure mobility Mobility. Helper mobility; Ptr<List. Position. Allocator> position. Alloc = Create. Object<List. Position. Allocator> (); position. Alloc->Add (Vector (0. 0, 0. 0)); position. Alloc->Add (Vector (5. 0, 0. 0)); position. Alloc->Add (Vector (0. 0, 5. 0, 0. 0)); mobility. Set. Position. Allocator (position. Alloc); mobility. Set. Mobility. Model ("ns 3: : Constant. Position. Mobility. Model"); mobility. Install (ap); mobility. Install (sta); // other set up (e. g. Internet. Stack, Application) ns-3 training, June 2016 17

Athstats helper Hooks Wi-Fi traces to provide debugging similar to Madwifi drivers Example athstats output from example. /waf --run wifi-ap m_tx. Count m_rx. Count unused short long exceeded rx. Error 0 0 0 M 0 60 0 0 M 0 123 0 0 0 0 0 0 0 0 0 M 0 122 0 0 2 0 0 M 0 122 0 0 23 0 0 0 0 M 0 122 0 0 0 0 14 0 0 M 0 122 0 0 26 0 0 M 0 122 0 0 12 0 0 M ns-3 training, June 2016 18

LTE/Wi-Fi Coexistence ns-3 training, June 2016 19

Use case: LAA Wi-Fi Coexistence • ns-3 has been extended to support scenarios for LTE LAA/Wi-Fi Coexistence • Methodology defined in 3 GPP Technical Report TR 36. 889 • Enhancements needed: – Wireless models (LBT access manager, Spectrum. Wifi. Phy, propagation/fading models) – Scenario support (traffic models) – Output data processing ns-3 training, June 2016 20

Indoor 3 GPP scenario ns-3 training, June 2016 21

Indoor scenario details ns-3 training, June 2016 22

Outdoor 3 GPP scenario Outdoor layout: hexagonal macrocell layout. 7 macro sites and 3 cells per site. 1 Cluster per cell. 4 small cells per operator per cluster, uniformly dropped. ITU UMi channel model. Figure source: 3 GPP TR 36. 889 V 13. 0. 0 (2015 -05) ns-3 training, June 2016 23

References • ns-3 Wiki page: – https: //www. nsnam. org/wiki/LAA-Wi. Fi. Coexistence • module documentation • references to various publications • documentation on reproducing results • Code: – http: //code. nsnam. org/laa/ns-3 -lbt ns-3 training, June 2016 24

Sample results ns-3 training, June 2016 25

Wi-Fi enhancements ns-3 training, June 2016 26

Model enhancements: Wi-Fi • Spectrum Wi-Fi Phy implementation • Wi-Fi preamble detection based on AWGN and TGn Channel Model D • Wi-Fi RSS-based AP selection and roaming • Wi-Fi MIMO approximations to support 2 x 2 DL, 1 x 2 DL on AWGN and TGn Model D ns-3 training, June 2016 27

Model enhancements: LTE • LTE interference model relies on the simplifying assumption that all interfering signals are LTE and are synchronized at the subframe level. • LTE inteference model has been enhanced to handle inteference by signals of any type. • This relies on the ns-3 Spectrum framework. • The reception of LTE signals is evaluated by chunks, where each chunk is identified by a constant power spectral density. ns-3 training, June 2016 28

Scenario • An initial test scenario, useful for testing basic model operation in a small scale setting, grew into TR 36. 889 -like indoor and outdoor scenarios • D 1 and d 2 can vary and operator A and B can be both LTE or Wi-Fi ns-3 training, June 2016 29

Output experiment scripts • Shell scripts and gnuplot helpers to manage configuration and data output • (demonstrate) ns-3 training, June 2016 30

Status • Portions are being migrated into ns-3 -dev – Spectrum. Wifi. Phy in ns-3. 26 – LTE components, propagation model likely in ns-3. 27 – Scenario helper may be rewritten • Trying to decompose into pieces easy to merge • For more information: – https: //www. nsnam. org/wiki/LAA-Wi. Fi-Coexistence ns-3 training, June 2016 31