Improving QoS of VoIP Improving QoS of VoIP over Wireless Networks over Wireless Networks (IQ-VW) (IQ-VW) Mona Habib & Nirmala Bulusu Mona Habib & Nirmala Bulusu CS522 – 12/09/2002 1
Agenda Agenda � Voice over IP (VoIP): Why? � Voice over IP (VoIP): Why? � VoIP Protocols: H.323 and SIP � VoIP Protocols: H.323 and SIP � Quality of Service (QoS) � Quality of Service (QoS) � Wireless Networks � Wireless Networks � Testbed Configuration � Testbed Configuration � Testing Scenarios � Testing Scenarios � QoS Test Results � QoS Test Results � Comments � Comments 2
Why Voice over IP? Why Voice over IP? � Reduce toll costs for long-distance telephone calls � Reduce toll costs for long-distance telephone calls � Helps consolidate separate voice and data networks for � Helps consolidate separate voice and data networks for cost-effectiveness and bandwidth utilization. cost-effectiveness and bandwidth utilization. � Provides features not available in traditional voice � Provides features not available in traditional voice telephony, such as video conferencing and telephony, such as video conferencing and simultaneous data transmission (e.g. whiteboard) for simultaneous data transmission (e.g. whiteboard) for true multimedia communications. true multimedia communications. � Provides integration between data and telephony � Provides integration between data and telephony applications for business -- “click to talk” on a web site applications for business -- “click to talk” on a web site for ordering or customer support. for ordering or customer support. 3
Voice over IP Network Components Voice over IP Network Components SS7 Network SS7 Network Gatekeeper Gatekeeper Wireless Wireless IP Network IP Network Terminal Terminal ISDN ISDN Terminal Terminal PSTN PSTN MCU MCU Gateway Gateway Carrier Class Carrier Class Enterprise Class Enterprise Network Enterprise Class Enterprise Network PBX PBX Gateway Gateway Fax Fax 4
Voice over IP - The Standards Battle Voice over IP - The Standards Battle • H.323 • H.323 - Primary standard for enterprise networks - Primary standard for enterprise networks - Supported in many carrier networks - Supported in many carrier networks • SIP - Session Initiation Protocol • SIP - Session Initiation Protocol - Common for IP phones and PCs - Common for IP phones and PCs - Gaining popularity as signaling protocol due to its - Gaining popularity as signaling protocol due to its versatility versatility 5
H.323 Protocol Stack H.323 Protocol Stack Audio Terminal Control & Management Application Voice Codec H.225 G.711, 723, H.225 729, etc. RTCP Call H.245 RAS RTP Signaling TCP UDP IP Link & Physical Layer 6
SIP Protocol Stack SIP Protocol Stack Audio Terminal Control & Management Application Voice Codec G.711, 723, 729, etc. RTCP SIP SDP RTP TCP UDP IP Link & Physical Layer 7
Codec: Speech to Data Codec: Speech to Data Transforms between 101011110 Speech (analog) Bandwidth to data (digital) Algorithm G.723.1 G.729 G.728 G.726 Rate (Kbs) 5.3 - 6.3 8 16 32 Complexity Highest High Lower Low Compare with 64Kbs end to end Compare with 64Kbs end to end 8
Quality of Service Quality of Service Phone PSTN Network Gateway IP Network H.323/SIP Terminal Phone PSTN Network Gateway IP Network H.323/SIP Terminal Service Quality Voice Quality Service Quality Voice Quality • Offered Service Traditional PSTN In addition in IP Networks • Offered Service Traditional PSTN In addition in IP Networks • Reachability • Level • Delay • Reachability • Level • Delay • Availability • Delay • Delay-Jitter • Availability • Delay • Delay-Jitter • Reliability • Echo • Clarity: • Reliability • Echo • Clarity: • Price • Clarity: • Packet Loss • Price • Clarity: • Packet Loss • Intelligibility • Bandwidth • Intelligibility • Bandwidth • Noise • Compression • Noise • Compression • Fading • Fading • Cross talk • Cross talk 9
Wireless Networks Wireless Networks 802.11 is an IEEE standard for wireless LANs 802.11 is an IEEE standard for wireless LANs 802.11a and 802.11b are two variants of the standard 802.11a and 802.11b are two variants of the standard Most recent variant: 802.11g (compatible with 802.11b) Most recent variant: 802.11g (compatible with 802.11b) 802.11a 802.11b 802.11a 802.11b Operates in the 5 GHz � Operates in the 2.4 GHz Operates in the 5 GHz � Operates in the 2.4 GHz frequency band frequency band frequency band frequency band Supports bandwidths up to 54 � Supports bandwidths up to 11 Supports bandwidths up to 54 � Supports bandwidths up to 11 MB, range of 150+ feet MB , range of 150+ feet MB, range of 150+ feet MB , range of 150+ feet Has 12 data channels � Has 3 data channels Has 12 data channels � Has 3 data channels Uses Orthogonal Frequency � Uses Direct Sequence Spread Uses Orthogonal Frequency � Uses Direct Sequence Spread Division Multiplexing (OFDM) Spectrum modulation (DSSS) Division Multiplexing (OFDM) Spectrum modulation (DSSS) Performs at short distances � Handles long distances better Performs at short distances � Handles long distances better than 802.11a than 802.11a Incompatible with 802.11b Incompatible with 802.11b 10
Wireless Network Security Wireless Network Security � Vulnerabilities: � Vulnerabilities: � Unauthorized user access � Unauthorized user access � Eavesdropping (network can be tapped using a sniffer) � Eavesdropping (network can be tapped using a sniffer) � Authentication: EAP (Extensible Authentication Protocol) � Authentication: EAP (Extensible Authentication Protocol) � EAP interacts with a Remote Authentication Dial-In User � EAP interacts with a Remote Authentication Dial-In User Service (RADIUS) server to provide authentication for wireless Service (RADIUS) server to provide authentication for wireless client devices. client devices. � Encryption: WEP (Wired Equivalent Privacy) � Encryption: WEP (Wired Equivalent Privacy) � Scrambles the communication between the access point and � Scrambles the communication between the access point and client devices to keep the communication private. client devices to keep the communication private. � Both the access point and client devices use the same WEP � Both the access point and client devices use the same WEP key to encrypt and decrypt radio signals. key to encrypt and decrypt radio signals. 11
Wireless Network Configuration Wireless Network Configuration 12
QoS Testbed – HW Configuration QoS Testbed – HW Configuration Lab #2 Lab #1 Lab #2 Lab #1 Cisco Aironet Cisco Aironet Access Point RADIUS Server Access Point RADIUS Server Ethernet Client Ethernet Client vinci.uccs.edu vinci.uccs.edu wind.uccs.edu Wireless Client wind.uccs.edu Wireless Client (DHCP) (DHCP) Ethernet Client Ethernet Client Gatekeeper Gatekeeper wait.uccs.edu wait.uccs.edu calvin.uccs.edu calvin.uccs.edu Lab #3 Lab #3 Wireless Client Wireless Client (DHCP) (DHCP) 13
QoS Testbed – SW Configuration QoS Testbed – SW Configuration � Public Domain Software � Public Domain Software � Gatekeeper: Vovida Open Communication Application � Gatekeeper: Vovida Open Communication Application Library (VOCAL) Library (VOCAL) � VOCAL SIP to H.323 Converter: SIPH323CSGW � VOCAL SIP to H.323 Converter: SIPH323CSGW � Clients: MSN Messenger 4.6 (allows use of � Clients: MSN Messenger 4.6 (allows use of communication services other than .Net Passport) communication services other than .Net Passport) � Network Analyzer: Ethereal � Network Analyzer: Ethereal � Other Software: � Other Software: � QoS analysis tools provided by Daniel Hertrich � QoS analysis tools provided by Daniel Hertrich � Voice over Misconfigured Internet Telephones (VOMIT) � Voice over Misconfigured Internet Telephones (VOMIT) � Wavfix.c: Program to create WAVE file header. Used to � Wavfix.c: Program to create WAVE file header. Used to replay captured voice data replay captured voice data 14
QoS Testing Scenarios QoS Testing Scenarios � Ethernet to Ethernet � Ethernet to Ethernet � Ethernet to Wireless � Ethernet to Wireless � Ethernet to 802.11a � Ethernet to 802.11a � Ethernet to 802.11b � Ethernet to 802.11b � Ethernet to 802.11b + Wireless security � Ethernet to 802.11b + Wireless security � Wireless to Wireless � Wireless to Wireless � 802.11a to 802.11a � 802.11a to 802.11a � 802.11b to 802.11b � 802.11b to 802.11b � 802.11b to 802.11b + Wireless security � 802.11b to 802.11b + Wireless security � Ten test runs per scenario. Sound files include speech � Ten test runs per scenario. Sound files include speech (male and female) and music. (male and female) and music. 15
QoS Test Results QoS Test Results Sample Inter-packet Delay Graph Sample Inter-packet Delay Graph 802.11b - 802.11b 40 36 32 28 24 20 16 12 8 4 0 0 10 20 30 40 50 60 Tm e ( s e c ) 16
QoS Test Results QoS Test Results Sample Jitter Time Graph Sample Jitter Time Graph 802.11b - 802.11b 0.4 0.36 0.32 0.28 0.24 0.2 0.16 0.12 0.08 0.04 0 0 10 20 30 40 50 60 -0.04 -0.08 -0.12 -0.16 -0.2 -0.24 -0.28 -0.32 -0.36 -0.4 Ti m e ( s e c ) 17
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