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Performance Measurement of Performance Measurement of Wireless LAN - - PowerPoint PPT Presentation

Nov 10, 2023 462 likes •749 views

Performance Measurement of Performance Measurement of Wireless LAN Using Open Source Wireless LAN Using Open Source Vipin M Wireless Communication Research Group AU KBC Research Centre http://comm.au-kbc.org/ 1 Communication Research

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Communication Research Group @ AU - KBC

Performance Measurement of Performance Measurement of Wireless LAN Using Open Source Wireless LAN Using Open Source

Vipin M Wireless Communication Research Group AU – KBC Research Centre http://comm.au-kbc.org/

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Overview

  • General Network

– Why Network Performance Measurement ? – Network Performance Metrics – How Network Performance is Measured ? – Measurement Methods

  • Ex: Pair Packet

– Active Probing Tools

  • Ex: Iperf
  • Wireless Network

– Performance Measurement In Wireless LAN – PHY / MAC / Higher layer Measurement – Measuring Methods and setups

  • Effect in Wireless

– Effect of these Metrics – Some Results

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Why Network Performance Measurement ?

– What are the factors affecting network Performance ? – How this factors affecting Performance ? – Impacts made to the user because of these ?

P 1 P 2 Router Router Network Cloud

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Network performance metrics

  • One-Way Delay (OWD)

– Serialization Delay – Propagation Delay – Queuing Delay – Forwarding Delay

  • Round-Trip Time (RTT)
  • Delay Variation (Jitter)
  • Packet Loss

– Congestion – Errors

  • Packet Reordering
  • Maximum Transmission Unit (MTU)
  • Available Bandwidth ( Throughput )
  • Link Capacity
  • Bandwidth Delay Product (BDP)
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How Network Performance is Measured

P 1 P 2 Router Router Network Cloud

TCP or UDP IP MAC PHY Application

Router Router Network Cloud Tool Tool Tool

TCP or UDP IP MAC PHY Applicat ion

Tool Tool Tool

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Measurement Methods

Metric

– Distance

  • Per-hop
  • End-to-End

– Values

  • Bulk Transfer
  • Achievable
  • Bottleneck / Minimum

Methods ( Ex: for IP layer )

– Variable Packet Size – Packet Pairs / Trains – Self – Loading Periodic Streams – Parallel Connection

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Ex: Pair Packet technique for Capacity

– Two packet of size L send back to back – Packets receive with ∂ time space dispersion

Time = Size (L) / Capacity (C) C = L / T ∆out = L / C0 ∆out = Max(∆in, L/Ci) Dispersion ∂ = ∆out - ∆in Dispersion ∂ = Max (L/Ci) Min(Ci) -> end-to-end Capacity Capacity C = L / ∂

Packet 1 Packet 2 L L Packet 1 Δ in Δ out Input Packet Pair Output Packet Pair Packet 2 ....

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Packet 1 L

Δ in

Cin C1 C2 C3 Cout In Out Packet 2 L Packet 1

Δ 1

Packet 2 Packet 1

Δ 2

Packet 2 Packet 1

Δ 3

Packet 2 Packet 1

Δ out

Packet 2

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Active Probing Tools

– Throughput & Delay Measurement Tools

  • Ping
  • Traceroute
  • Iperf
  • Thrulay

– Path Characterization & Bandwidth Estimation

  • pathChirp
  • Pathload
  • ABwE
  • Netperf
  • Nettest
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Iperf

P 1 P 2 Router Router Network Cloud Generate Packet Receive the packets and send the Report Iperf Client Iperf Server

– Components

  • Server
  • Client

– Modes

  • TCP
  • UDP
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Wireless LAN

– Last Hop Connectivity is Wireless – Bottleneck will be always at wireless – What are the Network Parameters that make major effects ? – How it is effecting ?

Internet Modem WLAN AP Laptop with WLAN Capable Laptop with WLAN Capable PDA with WLAN Capable

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Performance Measurement in WLAN

PHY Layer

– Received Signal Power – Signal To Noise Ratio – Bit Error Rate – Throughput – Interference

MAC Layer

– Throughput – Retries – Received Data Rate – Queuing Delay – Packet Error Rate – Power Consumption

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WLAN PHY / MAC Measurement

– Using MAC Packet injecting / and process Tools

  • Approximate PHY and MAC Parameters can be Measured
  • This depend on the implementation of hardware

– Tools like libmac, netlib-80211b etc

TCP or UDP / I P Higher MAC Low er MAC Application User Tool User Function PHY User Kernel Hardware

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WLAN Phy Signal Measurement

– Wispy + Spectool-GTK (Kismet) – Information from lower layer (Modified driver)

Courtesy : Kismet

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WLAN Higher Layer Measurement

– This is as similar as the normal wired network – Then what is the difference ? – Parameters

  • Jitter
  • Throughput
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Performance Measurement in WLAN

Linux Laptop

+ Iperf / Jperf ( P1 ) Access Point

Commercial

  • ff the shelf products

Linux Laptop

+ Iperf / Jperf ( P2 )

– Performance Measurement

  • P1 in Wireless and P2 in Wired Network
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Performance Measurement in WLAN

– Performance Measurement

  • P1 in Wireless and P2 in Wired Network
  • Both P1 and P2 in Wireless

Linux Laptop

+ Iperf / Jperf ( P1 ) Access Point

Commercial

  • ff the shelf products

Linux Laptop

+ Iperf / Jperf ( P2 )

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Test Setup

Linux Laptop

+ Iperf / Jperf ( P1 ) Access Point

Commercial

  • ff the shelf products

Linux Laptop

+ Iperf / Jperf ( P2 )

“Iperf –c <host>” Iperf -c 192.168.2.73

  • p <num_streams> test with parallel TCP streams
  • w <buffer_size> set socket buffer size

“Iperf -s -D > iperfLog ” Iperf -s -D /var/log/iperfLog

Iperf can run as a daemon

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Server Client

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Jperf (GUI for Iperf)

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Bandwidth Graph

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Effect of these Metrics

  • Major parameters effecting the WLAN

– PHY

  • Interference
  • RSSI
  • SNR
  • Data Rate

– MAC

  • Queuing Delay
  • Packet Loss / Errors
  • Available Bandwidth ( Throughput )

– IP

  • Delay Variation (Jitter)
  • Available Bandwidth ( Throughput )
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Channel Interference

Courtesy : [3]

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Signal Strength vs. Received Rate

Courtesy : [2]

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Distance Vs Throughput

Courtesy : Atheros

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Thank You

Questions ? Contact : vipintm@au-kbc.org

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Reference

  • 1. IEEE 802.11,a,b,g,n IEEE Standard
  • 2. Bandwidth Estimation: Metrics, Measurement

Techniques, and Tools, Ravi Prasad CAIDA

  • 3. Enhancement of a WLAN-Based Internet Service,

Youngkyu Choi, Multimedia & Wireless Networking Laboratory, School of Electrical Engineering, Seoul National University, Korea.

  • 4. Throughput Measurement for UDP Traffic in an IEEE

802.11g WLAN, Alexander L., Department of Computer and Information Sciences Towson University.

  • 5. Measured Performance of 5-GHz 802.11a Wireless LAN

Systems, James C. Atheros Communications, Inc.

  • 6. Iperf http://dast.nlanr.net/Projects/Iperf/