Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p Daniel Richter, Jossekin Beilharz, Lukas Pirl, Christian Werling, and Andreas Polze Operating Systems & Middleware Group Hasso Plattner Institute at University of Potsdam, Germany
Motivation IEEE 802.11 Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications ▪ set of standards for wireless communication ▪ local networks with little device mobility ▪ modes of operation ▪ BSS/AP (Basic Service Set/Access Point) ▪ IBSS ( Independent BSS , ad-hoc) ▪ … Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p 2 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Motivation IEEE 802.11p 802.11 Amendment 6: Wireless Access in Vehicular Environments ▪ high mobility of devices in rapidly changing environments ▪ connection and communication in very short periods of time ▪ OCB mode (Outside the Context of a BSS) ▪ think: broadcast; no authentication, no association Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p 3 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Motivation ▪ vehicular environments 4 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Motivation Car-to-X → Rail-to-X ▪ transfer of maintenance data of critical infrastructure elements ▪ e.g. largely self-sufficient units such as level crossings with monitoring signals, diagnostic systems of switches, or weather stations close to the tracks Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p 5 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Motivation ▪ data transfer via passing trains ▪ via dedicated short-range communications ▪ potentially higher vehicular speeds (vs. Car2X) ▪ potentially higher disturbances Photo: Sven Teschke / License: Creative Commons CC-by-sa-3.0 de Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p 6 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Motivation ▪ focus on an extremely short timespan for connection and communication (approx. 100 ms) ▪ compare latencies of networks ▪ OCB mode 802.11p 5.9 GHz ▪ IBSS (ad-hoc) 802.11n 5 GHz ▪ BSS/AP (access point) 802.11n 5 GHz ▪ response to disturbances of OCB mode ▪ real-time applications → latencies Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p 7 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Background Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p
Background IEEE 802.11p V2X standard in Europe and US for vehicular ad hoc networks ▪ PHY layer (OSI layer 1) ▪ frequency: ~5.9 GHz ▪ 7 channels of 10 MHz bandwidth (Europe) ▪ MAC layer (OSI layer 2) ▪ OCB mode (Outside the Context of a BSS, think: broadcast) ▪ no authentication ▪ no association 9 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Background Modes of Operation 802.11 working on a 2.4 GHz for many years, switched to less crowded 5 GHz band ▪ Basic Service Set (BSS) ▪ Access Point ( AP ) infrastructure mode ▪ Ad-Hoc / Independent BSS ( IBSS ) mode ▪ Mesh, Monitor, … 802.11p facilitates the 5.9 GHz band ▪ OCB mode (Outside the context of a BSS) 10 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Background Related Work ▪ performance of 802.11p under various conditions ▪ analytically, A. A. A. Almohammedi, N. K. Noordin, A. Sali, F. Hashim , and S. Saeed, “A comprehensive performance analysis of IEEE 802.11p based MAC for vehicular communications under non- saturated conditions,” Journal of ICT Research and Applications, vol. 11, no. 1, pp. 91– 112, 2017. ▪ in simulations, S. Gräfling, P. Mähönen, and J. Riihijärvi , “Performance evaluation of IEEE 1609 WAVE and IEEE 802.11p for vehicular communications,” in Ubiquitous and Future Networks (ICUFN), 2010 Second International Conference on. IEEE, 2010, pp. 344 – 348. Z. Hameed Mir and F. Filali , “LTE and IEEE 802.11p for vehicular networking: a performance evaluation,” EURASIP Journal on Wireless Communications and Networking, vol. 2014, p. 89, May 2014. K. Bilstrup, E. Uhlemann, E. G. Strom, and U. Bilstrup , “Evaluation of the IEEE 802.11p MAC method for vehicle -to- vehicle communication,” in Vehicular Technology Conference, 2008. VTC 2008-Fall. IEEE 68th. IEEE, 2008, pp. 1 – 5. ▪ experimentally S. Demmel, A. Lambert, D. Gruyer, A. Rakotonirainy, and E. Monacelli , “Empirical IEEE 802.11p performance evaluation on test tracks,” in Intelligent vehicles symposium (IV), 2012 IEEE. IEEE, 2012, pp. 837– 842. V. Shivaldova, G. Maier, D. Smely, N. Czink, A. Alonso, A. Winkelbauer, A. Paier, and C. F. Mecklenbräuker , “Performance evaluation of IEEE 802.11p infrastructure-to- vehicle tunnel measurements,” in Wireless Communications and Mobile Computing Conference (IWCMC), 2011 7th International. IEEE, 2011, pp. 848 – 852. M. Kloc, R. Weigel, and A. Koelpin , “SDR implementation of an adaptive low -latency IEEE 802.11p transmitter system for real- time wireless applications,” in 2017 IEEE Radio and Wireless Symposium (RWS), Jan. 2017, pp. 207– 210. B. Bloessl, M. Segata , C. Sommer, and F. Dressler, “Performance Assessment of IEEE 802.11 p with an Open Source SDR -based Prototype,” IEEE Transactions on Mobile Computing, vol. 17, no. 5, pp. 1162– 1175, 2018. ▪ most studies only look at throughput, packet loss, and signal range ▪ latencies (especially incl. establishing a connection) rarely investigated 11 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Background Related Work – T estbed Setup ▪ Lisový et al.: implementing 802.11p’s amendments into different Linux subsystems R. Lisový, M. Sojka, and Z. Hanzálek , “IEEE 802.11p Linux Kernel Implementation ,” Czech Technical University in Prague, Tech. Rep., 2014. ▪ first-hand practical info on the Linux 802.11p support ▪ concise summary of 802.11p’s changes and their motivation ▪ Fernández: compatible hardware J. Fernández Pastrana , “802.11p standard and v2x applications on commercial wi-fi cards,” Master’s thesis, Universidad de Valladolid. Escuela Técnica Superior de Ingenieros de Telecomunicacin, 2017. ▪ states positively tested cards with 802.11p support ▪ gives insights into the physical requirements to such cards in general 12 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
T estbed Setup Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p
T estbed Setup ▪ since no off-the-shelf hardware is sold with 802.11p support, we had to patch drivers and adjust the operating system configuration Hardware ▪ wireless cards officially supporting 802.11p scarcely found online ▪ several 5 GHz wireless physically able to support 5.9 GHz band [Fernández] Software ▪ some minor patches to the drivers are needed to make 802.11p usable for applications [Lisový et al.] 14 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
T estbed Setup Hardware Testbed setup A Testbed setup B ▪ Wireless card ▪ Wireless card ▪ Qualcomm Atheros ▪ Qualcomm Atheros AR5B22 Mini PCI-e AR9462 ▪ Chipset: AR9462 ▪ 2.4/5 Ghz WLAN + Bluetooth ▪ Mini PCI-e to PCI-e adapter: adaptare 49006 ▪ HPE GL20 IoT Gateway ▪ Dell Workstation ▪ Intel I5-4300U CPU ▪ Intel Core i5-3470 CPU ▪ 8 GB RAM ▪ 8 GB RAM In both setups the distance between the communicating nodes is 0.5 meters due to laboratory conditions. 15 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
T estbed Setup Software ▪ Ubuntu 16.04 LTS with Linux kernel 4.13.0-31- generic x86 64 ▪ Linux because existing implementation of 802.11p’s changes into its 802.11 subsystems ▪ 802.11p / OCB mode awareness: ▪ kernel (BSSID in mac80211, commands in cfg80211 and nl80211 to virtually join & leave OCB network and sending and receiving) ▪ tools (e.g. iw 4.0 and later) ▪ regulatory database (wireless-regdb) [Lisový et al.] 16 Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p | HICSS-52 | Daniel Richter | January 11, 2019
Benchmarks Performance of Real-Time Wireless Communication for Railway Environments with IEEE 802.11p
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