Jaime Johnson Yuhang Lin Nathan Daniel Anil Koneri Vineeth Chander Project Presentation 802.11n : Performance & Evaluation Jaime Johnson Yuhang Lin Nathan Daniel Anil Koneri Vineeth Chander

Context, Problem Statement, Motivation Theoretical study of 802.11a/b/g/n by identifying key components in protocols and understanding technologies. Testing & Comparing 802.11n performance with other 802.11 standards (a/b/g) in terms of throughput under different scenarios. 802.11n achieves higher data rates, longer range and more reliable coverage than previous Wi-Fi technologies.

Key Project Milestones Theoretical Study of 802.11n/a/b/g - Accomplished Testbed Setup – Accomplished Scenario Design – Accomplished Throughput measurement – Accomplished Analysis of Results – Accomplished Comparing technologies in 802.11n (optional) – Not accomplished

Milestone 1:Theoretical Study Technical Documents: Designed for speed by Peter Thornycroft (White paper doc. By ARUBA networks) Analyzing WLAN 802.11n by Rolf Leutert (Leutert NetServices) Identify key components in protocol Understand core technologies relating to 802.11n Compare different compatibility modes for 802.11n

Milestone 2:Testbed Setup Basic Topology: LaptopwiredWireless APwirelessLaptop Performance Evaluation: Iperf software Server Linksys WRT600N Client 802.11a 802.11b 802.11g 802.11n – 20 MHz 802.11n – 40 MHz Upstream 26 Mbits/s 4.06 Mbits/s 22.1 Mbits/s 33.1 Mbits/s 72 Mbits/s Downstream 27.9 Mbits/s 5.83 Mbits/s 25 Mbits/s 38.9 Mbits/s 79.3 Mbits/s

Milestone 3:Scenario Design for Experiments Horizontal distance between AP & Laptop Indoors or Outdoors LOS or non-LOS Interference: co-existing a/b/g/n links Mobility & fading: in elevator Vertical distance: on different floors

Midterm Presentation Review Include instantaneous throughput in addition to average throughput 802.11n TCP vs. UDP comparison Impact of mobility in the horizontal direction, car experiment. Which channels were used for measurements, which one least/most interfered ?

Milestone 4:Throughput measurements 30 packets, Avg. throughput = 46.4 Mbits/sec

Measurements contd. UDP 5GHz TCP 5GHz Scenario 802.11a 802.11n 20MHz Vertical Distance 25.0 Mbits/sec 28.0 Mbits/sec 54.0 Mbits/sec Horizontal Distance 28.4 Mbits/sec 50.0 Mbits/sec 78.6 Mbits/sec Non-LOS 29.0 Mbits/sec 48.6 Mbits/sec 56.6 Mbits/sec Indoor-Outdoor 18.4 Mbits/sec 30.0 Mbits/sec 47.6 Mbits/sec TCP 5GHz Scenario 802.11a 802.11n 20MHz 802.11n 40Mhz Vertical Distance 14.1 Mbits/sec 18.6 Mbits/sec Horizontal Distance 19.2 Mbits/sec 26.2 Mbits/sec Non-LOS 19.4 Mbits/sec 26.0 Mbits/sec Indoor-Outdoor 15.5 Mbits/sec 18.7 Mbits/sec

Measurements contd. UDP 2.4GHz TCP 2.4GHz Scenario 802.11b 802.11g 802.11n 20MHz 802.11n 40Mhz Vertical Dist. 5.3 Mbits/sec 23.7 Mbits/sec 35.6 Mbits/sec 71.6 Mbits/sec Horizontal Dist. 5.5 Mbits/sec 26.3 Mbits/sec 38.3 Mbits/sec 50.7 Mbits/sec Non-LOS 26.4 Mbits/sec 23.6 Mbits/sec 59.3 Mbits/sec Indoor-Outdoor 4.6 Mbits/sec 19.2 Mbits/sec 32.1 Mbits/sec 52.7 Mbits/sec TCP 2.4GHz Scenario 802.11b 802.11g 802.11n 20MHz 802.11n 40Mhz Vertical Dist 4.12 Mbits/sec 15.7 Mbits/sec Horizontal Dist 4.25 Mbits/sec 16.4 Mbits/sec Non-LOS 3.05 Mbits/sec 18.1 Mbits/sec Indoor-Outdoor 3.87 Mbits/sec 13.8 Mbits/sec

Milestone 5: Analysis of Results 802.11n outperforms 802.11a in both UDP & TCP for the 5Ghz band. 802.11n outperforms 802.11b/g in both UDP for the 2.4Ghz band. 802.11a operates in 5GHz band making it hard to penetrate walls and other obstructions. 802.11b/g have low max. speed and can interfere with home appliances that work on 2.4GHz band. 802.11n makes use of MIMO technology by using multiple antennas. MIMO relies on multipath signals, these were perceived as interference in 802.11a/b/g while MIMO uses multipath signal’s diversity to increase receiver’s ability to recover message from signal.

Analysis contd. 5GHz band gives better throughput than 2.4GHz band.

Analysis contd. UDP 5GHz band 11n 40MHz. 2.4 GHz band 11n 40 MHz Horizontal Distance 78.6 Mbits/sec 50.7 Mbits/sec 40MHz channel is not recommended for 2.4GHz band due overlap in frequency of transmissions. UDP 5GHz band 11n 40MHz. 2.4 GHz band 11n 40 MHz Vertical Dist. 54 Mbits/sec 71.6 Mbits/sec Non-LOS 56.6 Mbits/sec 59.3 Mbits/sec Indoor-Outdoor 47.6 Mbits/sec 52.7 Mbits/sec 2.4GHz band has longer wavelength compared to 5GHz, hence easier to maneuver through obstacles.

Analysis contd. UDP 5GHz band 11n 40MHz. Horizontal Dist. 78.6 Mbits/sec Vertical Dist. 54 Mbits/sec Non-LOS 56.6 Mbits/sec Indoor-Outdoor 47.6 Mbits/sec As client to server distance decreases throughput increases. As vertical dist. increases throughput falls considerably due to thickness/ nature of floors & walls. In case of Non-LOS, MIMO technology aids 11n throughput. In outdoor environments beyond 12ft. connection establishment failed.

Analysis contd. TCP achieves significantly less throughput compared to its UDP counterpart in all scenarios.

Challenges Elevator scenario – problems establishing connectivity, weak signal strength & link quality Different environments in different buildings on campus Maximum sending rate of packets was 100Mbits/s Interfering Ad hoc networks Multiple runs – connectivity problems, weather, interference. Horizontal mobility, car experiment: laptop battery power vs. connectivity in car

Summary 802.11n outperformed 802.11 a/b/g in the 2.4Ghz and 5Ghz bands for TCP and UDP. Instantaneous and average throughput data collected and studied for both TCP and UDP. Out of 6 milestones 5 were accomplished. Scenarios like vertical mobility, few TCP measurements could not be taken. Milestone 6 (Optional): comparing different technologies of 802.11n

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