Voice over Wi-Fi and Wi-Fi to Cellular Roaming

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					Voice over Wi-Fi and
Wi-Fi to Cellular Roaming
Wi-Fi Voice Conference
Paris, May 2005

Fanny Mlinarsky




                    Azimuth Confidential
 Cell-WiFi Convergence


                                  Cellular Network
                                                       Base
                                                      Station
Dual-Mode                                            Controller       Core
 Handset                                              (BSC)          Mobile
                                                                    Network

                                        IP
                                      Network
                                                       Call
                                                     Gateway




• Significant Cell-WiFi Convergence efforts
  fuse WiFi, IP and cellular technologies                              VoIP
     – Single phone works indoors and out                         Cellular Wi-Fi
     – Better coverage indoors at lower cost

Azimuth Confidential                                                      Slide 2
 Cell-WiFi Convergence Standards

• 3GPP GAN (generic access network),
  a.k.a. UMA (unlicensed mobile access)
     – An extension of GSM/GPRS
       3GPP* to Wi-Fi
     – Alcatel, AT&T Wireless,
       British Telecom, Cingular,
       Ericsson, Kineto Wireless,
       Motorola, Nokia, Nortel Networks,
       O2, Rogers Wireless, Siemens,
       Sony Ericsson, T-Mobile US
• 3GPP WLAN Interworking (IMS)
     – VoIP, SIP-based
     – SBC, Bellsouth, Cingular, Rogers (Canada), Telefonica (Mexico), Mobilkom
       (Austria), GoMobile (Malta), Azaire Systems
• SCCAN (seamless converged communication across networks)
     – First converged system
     – Proxim, Motorola, Avaya

                                                   *3rd Generation Partnership Project
Azimuth Confidential                                                              Slide 3
 VoWiFi IP-Based Systems
• VoWiFi
     –   WiFi phones available since 1999
     –   Cisco, Symbol, Spectralink
• Most IP PBXs use
  proprietary protocols
     –   Cisco SCCP
         (skinny call control protocol)
     –   Alcatel UA
     –   NEC Protims
     –   Avaya CCMS
     –   Nortel UniStim
     –   Siemens CorNet IP
     –   Mitel MiNet
     –   Spectralink SVP
• Standard IP telephony protocols
     –   Session Initiation Protocol (SIP)
     –   H.323
     –   Media Gateway Control Protocol (MGCP)




Azimuth Confidential                             Slide 4
 Voice Network Requirements
• Minimize bursty packet loss by controlling roaming time
              802.11r Fast Roaming
              802.11k Radio Resource Measurement (RRM)
              802.11i Pre-authentication


• Maintain isochronous nature of voice packet
  streams by controlling delay, jitter and packet loss
              802.11e Quality of Service (QoS) prioritization




Azimuth Confidential                                            Slide 5
  IEEE 802.11 Standards

                                         802.11s      802.11p
                                          Mesh         WAVE

                                         802.11r     802.11u
                                        Fast Roam    WIEN SG
                         802.11h
                        DFS & TPC        802.11e      802.11v
                                          QoS          WNM
      802.11 (’99)        802.11i
        MAC +             Security                                          ADS SG
                                         802.11k
      2Mbps PHY
                                          RRM         802.11n
                           802.11f
                                                       High                 APF SG
MAC                       Inter AP
                                                    Throughput    802.11T
                                        802.11m
                                                    (>100 Mbps)    Test
                                         Maint
PHY                     802.11a (’99)                             Methods
                          54 Mbps
                         5GHz PHY                                           Study
      802.11b (’99)       802.11g                                           Groups
        11 Mbps           54 Mbps                   Current
      2.4GHz PHY        2.4GHz PHY
                                                     Work

             Published
 Azimuth Confidential                                                        Slide 6
 QoS Protocols
• WMM (Wireless MultiMedia)
     –   Subset of 802.11e
     –   Specifies 4 priorities: voice (highest), video, background, best effort (lowest)
     –   Wi-Fi certification has started in September 04
• AC (Admission Control)
     –   Subset of 802.11e
     –   Enables APs to reject calls when call capacity is reached
• WMM SA (WMM Scheduled Access)
     –   Subset of 802.11e
     –   Specifies polling mechanism to optimize bandwidth utilization
     –   Wi-Fi certification expected in July 05
• APSD (Automatic Power Save Delivery)
     –   Subset of 802.11e
     –   Unscheduled APSD works with WMM
     –   Scheduled APSD works with WMM-SA
• SVP (Spectralink Voice Priority)
     –   Proprietary prioritization scheme that combines priority mechanism with tight synchronization
         to optimize bandwidth utilization



Azimuth Confidential                                                                        Slide 7
 Security Protocols

• WPA
     –   Subset of 802.11i
     –   TKIP, WEP
     –   EAP-TLS, PSK (pre-shared key)
     –   WPA Enterprise (TLS, PSK)
     –   WPA Personal (PSK)

• WPA2
     –   Entire 802.11i
     –   Superset of WPA
     –   AES support
     –   Pre-Authentication to help with 802.11r fast roaming




Azimuth Confidential                                            Slide 8
      WFA and IEEE Timeline
IEEE                                11e                                               11k                           11r        11n
Standards                                                                                                           11p        11s
Core Wi-Fi                                    802.11a+b+g (basic wireless LAN IEEE Specs)
Functionality
                                                                      802.11h+d

                                                      WMM (802.11e-based QoS)

                                                                                 WMM Scheduled Access
Multimedia
Enablers                                                                              WMM Power Save

                                                                     Consumer Electronics Framework phase 1

                                                                                      Consumer Electronics Framework phase 2

                                          Wi-Fi Protected Access (WPA) (802.11i-based Security)

                                                           WPA2 (full 802.11i)

Security                                                        Extended EAP (Enterprise)

                                                                                    Public Access

                                                                                             Simple Configuration

Voice & Data                                                             Wi-Fi Cellular Convergence (WCC)
Convergence
                                                                                            Voice over Wi-Fi




                Q1/05       Q2/05    Q3/05           Q4/05           Q1/06          Q2/06            Q3/06          Q4/06

     Azimuth Confidential                                                                                      Slide 9
 Voice Quality

• ITU-T Voice Quality Standards
     – MOS (mean opinion score)
       uses a wide range of human
       subjects to provide a subjective
       quality score (ITU-T P.800)

     – PESQ (perceptual speech quality measure)
       sends a voice pattern across a network and
       then compares received pattern to the original
       pattern and computes the quality rating (ITU-T P.862)

     – E-Model
       computes Rating Factor or R-Factor as a function
       of delay and packet loss;
       R-Factor directly translates into MOS (ITU-T G.107)


Azimuth Confidential                                           Slide 10
 ITU-T PESQ Model




Azimuth Confidential   Slide 11
 ITU-T E-Model (G.107)




Azimuth Confidential     Slide 12
 E-Model Parameters
    Parameter                                 Abbr.   Unit    Default Value   Permitted Range
    Send Loudness Rating                       SLR     dB          +8              0 … +18
    Receive Loudness Rating                    RLR     dB          +2             -5 … +14
    Sidetone Masking Rating                   STMR     dB          15              10 … 20
    Listener Sidetone Rating                  LSTR     dB          18              13 … 23
    D-Value of Telephone, Send Side            Ds       -           3              -3 … +3
    D-Value of Telephone Receive Side          Dr       -           3              -3 … +3
    Talker Echo Loudness Rating               TELR     dB          65              5 …65
    Weighted Echo Path Loss                   WEPL     dB          110             5 ... 110
    Mean one-way Delay of the Echo Path         T      ms           0              0 … 500
    Round-Trip Delay in a 4-wire Loop           Tr     ms           0             0 … 1000
    Absolute Delay in echo-free Connections    Ta      ms           0              0 … 500
    Number of Quantization Distortion Units    qdu      -           1              1 … 14
    Equipment Impairment Factor                 Ie      -           0              0 … 40
    Packet-loss Robustness Factor              Bpl      -           1              1 … 40
    Random Packet-loss Probability             Ppl      %           0              0 … 20
    Circuit Noise referred to 0 dBr-point      Nc     dBmOp        -70            -80 … -40
    Noise Floor at the Receive Side            Nfor   dBmp         -64                 -
    Room Noise at the Send Side                Ps     dB(A)        35              35 … 85
    Room Noise at the Receive Side             Pr     dB(A)        35              35 … 85
    Advantage Factor                            A       -           0              0 … 20

              G.107 – Default values and permitted ranges for the parameters
Azimuth Confidential                                                                            Slide 13
 R-Factor to MOS Conversion




Azimuth Confidential          Slide 14
 VoWiFi Performance

• QoS vs. capacity
• QoS vs. range
• QoS vs. WiFi-WiFi roam
• QoS vs. WiFi-cell roam




Azimuth Confidential       Slide 15
  VoWiFi Call Capacity Test

Test Description: Capacity vs. QoS Performance of Wi-Fi infrastructure

                                          Features

                                           • Emulate voice traffic from multiple
                                             phones


                                           • Emulate background data traffic


                                           • Measure delay, jitter and packet
                                             loss* vs. number of calls and
                                             background traffic



     Test Diagram       Test Results
                                                      * Per IETF RFCs 2544, 2889

 Azimuth Confidential                                                        Slide 16
    VoWiFi Call Capacity Test

Test Description: Capacity vs. QoS Performance of Wi-Fi infrastructure

                                          Features

                                           • Verifies the ability of infrastructure
                                             to prioritize voice traffic and to
                                             reject or redirect calls when
                                             capacity is reached
                                           • Test APs, wireless switches and
                                             other infrastructure devices
                                           • Measures infrastructure capacity
                                             vs. R-Factor and MOS quality
                                             scores computed from the
                                             measured packet loss rate, delay
+ click to enlarge
                                             and jitter
        Test Diagram     Test Results


  Azimuth Confidential                                                Slide 17
    VoWiFi Call Capacity Test

Test Description: Capacity vs. QoS Performance of Wi-Fi infrastructure

                                          Features

                                           • Verifies the ability of infrastructure
                                             to prioritize voice traffic and to
                                             reject or redirect calls when
                                             capacity is reached
                                           • Test APs, wireless switches and
                                             other infrastructure devices
                                           • Measures infrastructure capacity
                                             vs. R-Factor and MOS quality
                                             scores computed from the
                                             measured packet loss rate, delay
+ click to enlarge
                                             and jitter
        Test Diagram     Test Results


  Azimuth Confidential                                                Slide 18
    VoWiFi Call Capacity Test

Test Description: Capacity vs. QoS Performance of Wi-Fi infrastructure

                                          Features

                                           • Verifies the ability of infrastructure
                                             to prioritize voice traffic and to
                                             reject or redirect calls when
                                             capacity is reached
                                           • Test APs, wireless switches and
                                             other infrastructure devices
                                           • Measures infrastructure capacity
                                             vs. R-Factor and MOS quality
                                             scores computed from the
                                             measured packet loss rate, delay
+ click to enlarge
                                             and jitter
        Test Diagram     Test Results


  Azimuth Confidential                                                Slide 19
    VoWiFi Call Capacity Test

Test Description: Capacity vs. QoS Performance of Wi-Fi infrastructure

                                          Features

                                           • Verifies the ability of infrastructure
                                             to prioritize voice traffic and to
                                             reject or redirect calls when
                                             capacity is reached
                                           • Test APs, wireless switches and
                                             other infrastructure devices
                                           • Measures infrastructure capacity
                                             vs. R-Factor and MOS quality
                                             scores computed from the
                                             measured packet loss rate, delay
+ click to enlarge
                                             and jitter
        Test Diagram     Test Results


  Azimuth Confidential                                                Slide 20
    VoWiFi Call Capacity Test

Test Description: Capacity vs. QoS Performance of Wi-Fi infrastructure

                                          Features

                                           • Verifies the ability of infrastructure
                                             to prioritize voice traffic and to
                                             reject or redirect calls when
                                             capacity is reached
                                           • Test APs, wireless switches and
                                             other infrastructure devices
                                           • Measures infrastructure capacity
                                             vs. R-Factor and MOS quality
                                             scores computed from the
                                             measured packet loss rate, delay
+ click to enlarge
                                             and jitter
        Test Diagram     Test Results


  Azimuth Confidential                                                Slide 21
 VoWiFi Handset Range Test
Test Description: Quality of Voice Transmission over Wi-Fi as a
Function of Path Loss, Roaming and Traffic Load

                                         Features

                                          • Automatically validates Voice over
                                            Wi-Fi performance in minutes
                                          • Standard benchmark test to analyze
                                            rate adaptation of handset and AP pair
                                          • Shows R-Factor and MOS
                                            performance of real time voice stream
                                            - measures packet loss, delay and
                                              jitter to formulate MOS score
                                          • Precise RF control allows for
                                            measurement of true range
                                            performance based on actual WiFi-
                                            enabled handsets
      Test Diagram     Test Results


Azimuth Confidential                                                  Slide 22
 VoWiFi Handset Range Test
Test Description: Quality of Voice Transmission over Wi-Fi as a
Function of Path Loss, Roaming and Traffic Load

                                         Features

                                          • Automatically validates Voice over
                                            Wi-Fi performance in minutes
                                          • Standard benchmark test to analyze
                                            rate adaptation of handset and AP pair
                                          • Shows R-Factor and MOS
                                            performance of real time voice stream
                                            - measures packet loss, delay and
                                              jitter to formulate MOS score
                                          • Precise RF control allows for
                                            measurement of true range
+ click to enlarge                          performance based on actual WiFi-
                                            enabled handsets
      Test Diagram     Test Results


Azimuth Confidential                                                  Slide 23
 VoWiFi Handset Range Test
Test Description: Quality of Voice Transmission over Wi-Fi as a
Function of Path Loss, Roaming and Traffic Load

                                         Features

                                          • Automatically validates Voice over
                                            Wi-Fi performance in minutes
                                          • Standard benchmark test to analyze
                                            rate adaptation of handset and AP pair
                                          • Shows R-Factor and MOS
                                            performance of real time voice stream
                                            - measures packet loss, delay and
                                              jitter to formulate MOS score
                                          • Precise RF control allows for
                                            measurement of true range
+ click to enlarge                          performance based on actual WiFi-
                                            enabled handsets
      Test Diagram     Test Results


Azimuth Confidential                                                  Slide 24
 VoWiFi Handset Range Test
Test Description: Quality of Voice Transmission over Wi-Fi as a
Function of Path Loss, Roaming and Traffic Load

                                         Features

                                          • Automatically validates Voice over
                                            Wi-Fi performance in minutes
                                          • Standard benchmark test to analyze
                                            rate adaptation of handset and AP pair
                                          • Shows R-Factor and MOS
                                            performance of real time voice stream
                                            - measures packet loss, delay and
                                              jitter to formulate MOS score
                                          • Precise RF control allows for
                                            measurement of true range
+ click to enlarge                          performance based on actual WiFi-
                                            enabled handsets
      Test Diagram     Test Results


Azimuth Confidential                                                  Slide 25
 VoWiFi Handset Range Test
Test Description: Quality of Voice Transmission over Wi-Fi as a
Function of Path Loss, Roaming and Traffic Load

                                         Features

                                          • Automatically validates Voice over
                                            Wi-Fi performance in minutes
                                          • Standard benchmark test to analyze
                                            rate adaptation of handset and AP pair
                                          • Shows R-Factor and MOS
                                            performance of real time voice stream
                                            - measures packet loss, delay and
                                              jitter to formulate MOS score
                                          • Precise RF control allows for
                                            measurement of true range
+ click to enlarge                          performance based on actual WiFi-
                                            enabled handsets
      Test Diagram     Test Results


Azimuth Confidential                                                  Slide 26
 VoWiFi Handset Range Test
Test Description: Quality of Voice Transmission over Wi-Fi as a
Function of Path Loss, Roaming and Traffic Load

                                         Features

                                          • Automatically validates Voice over
                                            Wi-Fi performance in minutes
                                          • Standard benchmark test to analyze
                                            rate adaptation of handset and AP pair
                                          • Shows R-Factor and MOS
                                            performance of real time voice stream
                                            - measures packet loss, delay and
                                              jitter to formulate MOS score
                                          • Precise RF control allows for
                                            measurement of true range
+ click to enlarge                          performance based on actual WiFi-
                                            enabled handsets
      Test Diagram     Test Results


Azimuth Confidential                                                  Slide 27
 VoWiFi Roaming Test

Test Description: Roaming Performance of Wi-Fi Handsets

                                       Features

                                       • Measures the roaming time and
                                         quality of voice vs. roam
                                       • Detailed breakdown of the roaming
                                         time helps optimize roaming algorithm
                                       • Motion and fail-over roaming
                                         emulation of real world scenarios
                                       • Precise RF control and distributed
                                         monitoring present a wealth of
                                         information on handset performance
                                         as a function of motion

      Test Diagram     Test Results



Azimuth Confidential                                               Slide 28
  Roaming Process

        AP1                                                      AP2                              AP1
max
                                                                                       Path to AP1

Atten

                                                                                       Path to AP2
min
                                              Test cycle

                                Data rate transition




                                                   t ASSOCIATE

                                                                   t DATA
                         t TRANSITION

                                                t SCAN
                                                  t ROAM
                       Last data packet                            First data packet
                           before roam                             after roam



Azimuth Confidential                                                                   Slide 29
                      Sample Roaming Test Results
                                       Fastest roaming client - test results reported by the Azimuth test script


                      0.2


                     0.18


                     0.16                                                                                          Assoc Resp > Data


                     0.14                                                                                          Assoc Req > Resp

                                                                                                                   Auth Resp > Assoc Req
Roam Time, Seconds




                     0.12
                                                                                                                   Auth Req > Resp

                      0.1
                                                                                                                   Probe > Auth Req

                     0.08                                                                                          Data > First Probe


                     0.06


                     0.04


                     0.02


                       0
                               1            2          3           4            5            6           7
                                                              Roam Number


                     Azimuth Confidential                                                                                      Slide 30
 Cell-WiFi Handover Test

                           Complete WiFi and
                             VoWiFi
                             performance,
                             conformance
                             and certification


                           QoS vs. WiFi-to-cell
                             handover


                           Cellular test




Azimuth Confidential                 Slide 31
 Wi-Fi is Proliferating

• Environments
     –   SOHO
     –   Enterprise
     –   Public access
     –   Outdoor campus
     –   MAN/WAN
     –   Transportation
     –   Military


• Triple-play Applications
     – Data
     – Voice
     – Video




Azimuth Confidential         Slide 32
 VoWiFi Call Capacity




Azimuth Confidential    Slide 33
 VoWiFi Call Capacity




Azimuth Confidential    Slide 34
 VoWiFi Call Capacity




Azimuth Confidential    Slide 35
 VoWiFi Call Capacity




Azimuth Confidential    Slide 36
 VoWiFi Call Capacity




Azimuth Confidential    Slide 37
 VoWiFi Handset Range




Azimuth Confidential    Slide 38
 VoWiFi Handset Range




Azimuth Confidential    Slide 39
 VoWiFi Handset Range




Azimuth Confidential    Slide 40
 VoWiFi Handset Range




Azimuth Confidential    Slide 41
 VoWiFi Handset Range




Azimuth Confidential    Slide 42

				
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