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Wireless Internet Telephony. Tom La Porta Director, Networking Techniques Research Department Bell Labs, Lucent Technologies. Outline. Background and Overview Transport mobility management and QoS wireless specific services Signaling and Control mobility management - PowerPoint PPT Presentation
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Wireless Internet Telephony
Tom La Porta
Director, Networking Techniques Research Department
Bell Labs, Lucent Technologies
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Outline
• Background and Overview
• Transport
– mobility management and QoS
– wireless specific services
• Signaling and Control
– mobility management
– call control and interworking
3
Mobile Internet Telephony - All IP
Goal: migrate wireless mobile access networks to IP
– Support the anticipated explosive growth of the wireless Internet• merging of services for wireline and wireless networks• merging of wireless voice and data networks
– Reduced product and operational costs of IP infrastructure• increased efficiency of packet-based networks for combining voice and data
Technical Challenges:
– Transport:• quality of service • real-time mobility management• wireless specific services
– Signaling and Control:• personal and device mobility• call control• interworking with existing telephony systems
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Current Cellular Networks: Circuit Switched
BS
BSC
MSC/VLR
PSTN &SS7
HLR
BS
BS
BSCBS: base stationBSC: BS controllerMSC: Mobile Switching CenterVLR: Visitor Location RegisterHLR: Home Location Register1. Air 2. Backhaul 3. Full Rate 4. Full Rate
• Link 1: Air Interface• compressed voice (8Kbps) on “dedicated” channel
• Link 2: Backhaul• compressed voice multiplexed on sub-rate circuits• BSC performs voice coding to 64 Kbps (one option)• BSC performs soft handoff or frame selection function (one option)
• Link 3-4: Full rate• full rate voice switched at MSC to the PSTN• MSC may perform voice coding and soft handoff
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Migration to All-IP: Packet Core
BS
Access PVG
Software Controller
PSTN &SS7
HLR
BS
BS
BS: base stationPVG: Packet-Voice GatewayHLR: Home Location Register
1. Air 2. Backhaul 3. Packet Voice 4. Full Rate
• Link 1: Air Interface• compressed voice (8Kbps) on “dedicated” channel
• Link 2: Backhaul• compressed voice multiplexed on sub-rate circuits• Access PVG performs soft handoff or frame selection function• Access PVG may perform voice coding
• Link 3: Packet Voice• RTP session between Access and Egress PVGs • Egress PVG may perform voice coding
• Link 4• full rate voice switched at Egress PVG to the PSTN
Access PVG
EgressPVG
Intranet
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All-IP
IP-BSC
Software Controller
PSTN &SS7
HLR
IP-BS
1. Air 2. Backhaul 3. Packet Voice 4. Full Rate
• Link 1: Air Interface• compressed voice (8Kbps) on “dedicated” channel
• Link 2: Backhaul• aggregated, compressed IP voice• IP-BSC performs soft handoff or frame selection function
• Link 3: Packet Voice• RTP session between Access and Egress PVGs • Egress PVC performs voice coding
• Link 4• full rate voice switched at Egress PVG to the PSTN
• Link 5: Packet voice to Internet
EgressPVG
IntranetIP-BS
IP-BS
IP-BSCInternet
5. Packet Voice
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Outline
• Background and Overview
Transport – mobility management and QoS
– wireless specific services: Soft Handoff and Paging
• Signaling and Control
– mobility management
– call control and interworking
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Current Telecom-Based Mobile Packet Networks: GPRSGeneral Packet Radio Service
• Compatible with cellular telecom networks+ may be deployed using existing infrastructure– requires separate advances from the Internet
• Specialized nodes manage mobility and forward packets+ requires no changes to fixed hosts or intermediate routers– results in triangular routing– special failure recovery mechanisms needed
• Packets are tunneled through the Intranet+ intermediate routers are not mobile-aware– difficult to perform QoS
• Inter-SGSN handoffs always managed by GGSN– high update overhead– slow handoffs
IntranetMDSGSN
GGSN
Host
Regular routingTunneled packetsusing special methods
InternetSGSN
RadioAccess
Networks
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Current Internet-Based Mobile Packet Networks: Mobile IP
• Compatible with regular IP networks and hosts+ most Internet advances apply
• Specialized agents manage mobility and forward packets
+ requires no changes to fixed hosts or routers– results in triangular routing– special failure recovery mechanisms needed
• Packets are tunneled through the Internet+ Internet routers are not mobile-aware– difficult to perform QoS
• Handoffs always managed by Home Agent– high update overhead– slow handoffs
• No paging– high update overhead
MD FA
HA
HostInternet
Regular routing
Tunneled packetsusing IP
FA
RadioAccess
Networks
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HAWAII: A Domain Based Approach to IP Mobility
• Distributed control: Enhanced reliability– host-based routing entries in routers on path to mobile
• Localized mobility management: Lower overhead, fast handoffs– updates only reach routers affected by a movement
• Minimized or Eliminated Tunneling: no triangular routing, easy QoS– dynamic, public address assignment to mobile devices
• Supports paging
Compatible with Mobile IP
DomainRouter
RR
R R R R
DomainRouter
RR
R R R R
Local mobility Local mobilityMobile IP
Internet
MD
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HAWAII: Local Mobility
Internet
Domain Router
R2 R3 R R
RR1
MD
• Initial host-based routing entries in routers shaded in yellow (DR, R1, R2)– minimizes number of host-based entries
• Update host-based routing entries in routers shaded in green (R3, R1)– minimizes number of routers processing updates– reduces handoff time
• Address of mobile device remains constant– allows uninterrupted communication– allows QoS entries in unaffected routers (yellow) to remain unchanged
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HAWAII Overhead
Domain Router
Router 1 Router 7...
BS-R1 BS-R20... BS-R1 BS-R20
• 39 users/sq. miles• users moves at 112 Km/hr.• base stations cover 7 Km2
Network Model
Message HAWAII @ DomainRouter
Mobile IP @ HomeAgent
Msg/sec % CPU util Msg/sec % CPU utilHawaii Registration 127.8 1.92 0 0Hawaii Updates 51.3 0.85 0 0M-IP Rgistration 48.4 7.6 574 91.2M-IP Updates 12.7 0.15 127.4 1.5Total 240.2 10.5 701.4 92.7
Comparison of most heavily loaded entities in each network: HAWAII DR processes 34% number of messages as M-IP HA HAWAII DR is utilization is 11% of M-IP HA
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HAWAII Handoff Delay: Packet Loss
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Audio (160B/20msec) Video (4KB/33msec)
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Voice (or other real-time applications): less disruption
–packets dropped due to late arrival:
HAWAII Performance: Handoff Delay
Drops/handoff (average)Protocol
1 level, 75 msecplayout delay
1 level, 100 msecplayout delay
2 level, 100 msecplayout delay
MIP (MIPV6) 9 6.5 7.8
MIP withforwarding
4 1.5 2.8
HAWAII 0.3 - 1.5 0 - 0.3 0.3 - 1
IP network delay
HAWAII
Local Mobile IP Roaming Mobile IP
Acceptable for voice
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Wireless Services: IP-Paging
• Hierarchical scheme – scaleable– allows load balancing between levels of routers
• Uses IP Multicast– no new protocols
• Alternatives– paging from Home Agent– paging from Foreign Agent
• Result: – Domain paging supports ~10% higher load than FA-Paging
DomainRouter
RR
R R R R
DomainRouter
RR
R R R R
Internet
MD
Paging entry
Multicast entries
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Wireless Services: IP Soft Handoff
• Goals– true end-to-end IP networking– leverage IP protocols (e.g., multicasting)– support efficient routing
• Challenges– traffic aggregation– processing overhead– QoS
DomainRouter
RR
R R R R
DomainRouter
RR
R R R R
Internet
MD
IP Soft Handoff
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Outline
• Background and Overview
• Transport
– mobility management and QoS
– wireless specific services
Signaling and Control– mobility management
– call control and interworking
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Integrated SIP Registrar and HLR
Integrate 3 key functions of HLR & IP (VoIP) servers
• mobility management
• security
• profile management
Support multiple standard interfaces• Wireless: ANSI 41, GSM / UMTS MAP
• Internet: VoIP (SIP, H.323), AAA (RADIUS)
Provide enhanced HLR functionality for Internet and wireless network users
CurrentIntegrateHLR/VoIP server
functions
MAP / SS7
IntegratedUser
Profile Database
Securitymanager
Pro
toco
lG
atew
ays
User locationmanager
CellularCellular
InternetInternetVoIP / IPAAA / IP
Next-Generation
Internet (VoIP)Internet (VoIP)VoIP server
IP security server
CellularCellular
HLR
User/mobile location managementUser/mobile location management
Security control (authentication Security control (authentication center, IP security server)center, IP security server)
Service profile DB managementService profile DB management
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Mobility Management: Terminal and User Mobility
Current Location Area
TerminalHome Switch Calling
party
Mobile Phone #Registration and locally assigned number
• Current telephone network– mobile phone number points to home network of device– home network points to current location based on registration information and locally assigned temporary phone numbers
Current Location Area
TerminalSIP Server Calling
party
SIP URLInformation from registrar
• SIP– personal URL defines a server– registrars and proxies point to devices– extra level of indirection of interworking with cellular phone
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Mobility Management
User mobility across networks (wireless, Internet) in addition to terminal mobility
• Manage profile information for a ‘user’, not a ‘wireless terminal’
• Call delivery to the current user terminal Unified user location DB
• Global roaming between network types
• Receive the same service anywhere Unified service profile
PSTN networks
Internet
Securitymanager
Userlocationmanager
User location DB
GSMphone
SIPterminal PSTN
phone
User
SIP user name (URL)Tel # 1 (MSISDN)
Tel #2
AMPS / PCSWireless
access networks
BS
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Preliminary Analysis: Internetworking with Super HLR
Call delivery from a SIP terminal to a GSM phone
No dual registration or routing number lookup with super HLR
15~30% less signaling message load
Modified call setup
PSTN/MAP
BS InternetServingMSC
HLR +
Call delivery (SIP )
Mobile registration
IP stream up to BS
SIP proxy
Home MSCRouting info. lookup
Modified registration
PSTN/MAP
BSInternet
ServingMSC
HLR+
Call delivery (SIP )
Dual registration
IP stream up to BS
SIP registrarSIP proxy
SIPterminal
Super HLR
IPIPWirelessWirelessAccessAccess
BSInternet
Call delivery (SIP )
MAP mobile registration
IP up to BS
HL
R SIP registrar+
SIP call proxyGW
PSTN
ServingMSC
SIPterminal SIP
terminal
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Call Control: Internetworking among wireless, VoIP, and PSTN networks
Develop general internetworking models and procedures
To avoid different procedures for each internetworking scenario
Call delivery to home/gateway MSC or SIP proxy
Location query to super HLR
Routing information if delivered to wireless mobile terminal
Call delivery to a mobile terminal
Extend the procedures for supplementary services
Use calling party’s protocol
Use called party’s protocol
sHLRUser
LocationServer
user profile
hMSC /gMSCSIP proxyPG 1
(2) LOCREQ/SRISIP location lookup
(10) locreq/SRI AckSIP loc. Lookup rsp
Serving MSCSIP UAPG 2
(6) ROUTEREQ / PRN
(7) routereq / PRN Ack
(3) Request Location(1) IAM / SIP INVITE
(12) Call delivery
(11) IAM / SIP INVITE
(4) DB
lookup
(9) Request Location RSP
(5) Request Route Info
(8) Request Route Info RSP
Core s-HLR operations
GSMphone
SIPterminal
PSTNphone
User
User location DB
SIP user nameDN1 (MSISDN)
DN2
Super HLR
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Super HLR : Architecture
Super HLR core servers
- Common functions across protocols
- Multiple server instances on a cluster of processors for system scalability
- Interworking function between protocols: O(n) versus O(n2) complexity
Super HLR common operations
- Protocol independent
Protocol gateways
- Performs protocol specific control
- Facilitates new protocol introduction
Integrated user profile DB
- Common database for a ‘user’
Super HLR Common
operations
MAP / SS7
VoIP / IP
AAA / IP
PG MAP
PG VoIP
PG AAAIntegrated
user profile Database
DBmanager
User locationmanger
Securitymanager
s-HLR core servers
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Summary
Mobile Internet Telephony requires:
• Transport advancements
– efficient mobility management
– QoS
– wireless services
• Signaling advancements
– additional levels of mobility
– interworking with cellular telephony
• Other Issues
– efficiency of Internet signaling over the air