UMTS RAN Performance Trouble Shooting Guidelines -Ericsson UMTS Mobility
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Transcript of Page 1 Hans Peter Schwefel PhD Course: UMTS Lecture 2, Fall03 PhD Course: UMTS and IP based mobile...
Page 1Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
PhD Course: UMTS and IP based mobile networksWerner Mohr, Ljupco Jorguseski, and Hans-Peter Schwefel
• Day 1 Architecture and Core Network Aspects (HPS)
• Day 2 Radio Resource Management and Radio Planning (LJ)
• Day 3 Radio Propagation (WM)
• Day 4 W-CDMA & TD-CDMA (WM)
• Day 5 Cell Structure & Outlook Beyond 3G (WM)
Organized by Ramjee Prasad
Page 2Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Content1. Performance & Network Planning
• Performance Impacting Factors, circuit switched planning approaches, packets switched planning
2. IP Quality of service and performance optimizations• Basic methods, implementation approaches• Protocol Enhancements (RoHC)
3. Session Initiation Protocol (SIP)• Architectures & Entities• Methods
4. IP based multimedia subsystems (IMS)• Architecture & components• Registration & Call Routing
5. Services6. Outlook: Beyond 3G Networks
Page 3Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Core Network PlanningDetermine topology, # and type of network elements and link capacities• Plus planning of radio cells (topic in subsequent lecture)
Based on operator requirements on:• Security • Availability/Reliability• Performance (Transmission-, Processing-, Queueing delays)
Input data for planning:• Traffic and Mobility models
– # subscribers, # active users during busy hours, # active PDP contexts, traffic characterisation
• Functional Requirements– E.g. number of supported APNs, supported security features, redundancy for high
availability
Page 4Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IP Protocol: Packet-Based Transport• Advantages of Packet-Based Transport (as opposed to circuit switched)
– Flexibility
– Optimal Use of Link Capacities, Multiplex-Gain for bursty traffic
• Drawbacks– Buffering/Queueing at routers can be necessary
– Delay / Jitter / Packet Loss can occur
– Overhead from Headers (20 Byte IPv4, 20 Byte TCP)
... and it makes performance modeling harder!!
Main motivation for Performance Modeling:• Network Planning• Evaluation/optimization of methods for congestion control & QoS provisioning
queueing
+
Page 5Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
The circuit switched scenario
• K channels• Users allocate one channel per call for certain call duration• If all channels are allocated additional starting calls are blocked• How many channels are necessary to achieve a call certain maximal
blocking probability?
Common Model Assumptions:• Calls are arriving according to a Poission Process (justified for large user
population, limit theorems for stochastic processes) with rate • Call durations are exponentially distributed with mean T (okay for voice
calls)
Page 6Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Computation of Blocking Prob.: M/M/K/K model
• Poisson arrival of calls (first ’M’ Markovian) with rate – ti : arrival time of call i
– Xi:=ti+1-ti : interarrival time
– Poisson process of rate lambda: • Xi independent and
• Pr(Xi<x)=1 - exp(- x)
• Exponentially distributed call holding times of rate 1/T per call (second ’M’)
• K ’Servers’ • No additional waiting room for calls beyond K
Illustration of exponential distribution (Prob. that call longer than x, leftmost curve)
Page 7Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Computation of blocking probabilities:M/M/K/K models
• Finite Birth-Death Process (see e.g. [Cassandras & Lafortune]):
– Probability of i calls active [using Chapman-Kolmogorov Equations]
pi := Pr(n=i) = p0 (T)i /i! , i=1,…,K
where p0 = 1/[(T)i /i!] (sum taken over i=0 to K)
– Probability of blocked call:
p(B) = pK = p0 (T)K /K!
[also known as Erlang-B formula]
2/T1/T 3/T K/T
K
Page 8Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Challenges in IP networks:• Multiplexing of packets at nodes (L3)
• Burstiness of IP traffic (L3-7)
• Impact of Routing (L3)
• Performance impact of transport layer, in particular TCP (L4)
• Wide range of applications different traffic & QoS requirements (L5-7)
+ Feedback: performance traffic model, e.g. for TCP traffic, adaptive applications (cross-layer optimization)
Challenges in Packet Switched Setting
HTTP
TCP
IP
Link-Layer
L5-7
L4
L3
L2
Traffic Model
Mobility Model
Network Model
Performance Values (Delay, Loss, etc.)
TCP / adaptive applics.
Page 9Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Network model example: M/M/1/K queue
• Poisson arrival of packets (first ’M’ Markovian) with rate • Exponentially distributed service times
of rate (second ’M’)• Single Server (1)• Finite waiting room (buffer) for K packets• Often also specified: service discipline
– Default: First-In-First-Out– Others: Processor Sharing, Last-In-First-Out,
Earliest Deadline First,...
Finite buffer (size K)
Page 10Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
M/M/1/K queue: Performance
• Finite Birth-Death Process (see e.g. [Cassandras & Lafortune]):
– Probability of i packets in queue [using Chapman-Kolmogorov Equations]
pi := Pr(n=i) = (1-)/(1- K+1) * i , where = /
1, i=0,…,K
– Probability of packet loss:
p(loss) = pK = (1-)/(1- K+1) * K
– Average Delay:
Ď = 1/[ (1-pK)] * /(1- K+1) * [(1- K)/ (1-) – K K ]
K
Page 11Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
More realistic models: ON/OFF Models
Parameters:
• N sources, each average rate
• During ON periods: peak-rate p
• Mean duration of ON and OFF times
ON & OFF Times exponential MMPP representation with N+1 states
Page 12Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Traffic models: General hierarchical models
• Mathematical /stochastic description of traffic• Frequently used: Several levels with increasing granularity
– E.g. 3 levels: sessions, connections, packets– Or: 5-level model:
Page 13Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Example: HTTP traffic model • ‘Main’ objects contain zero or more embedded objects that the browser retrieves
Correlated requests for embedded objects within retrieval of main object
HTTP Session (User A)
HTTP Session (User B)
HTTP Session (User C)...
Session Level
Download Phase 1 Download Phase 2 Dld. Phase 3 ...Idle timeRead time
’exit browser’’click’ ’click’
Dld. Phase K
’click’’start browser’
Get Main Object Get embedded Obj. 1 Get emb. Obj. 2 Get emb. Obj. N...
Connection/ Flow Level
Packet Level, TCP dynamics (not shown here)
• Statistics:– Session arrivals: Renewal process (Poisson)– Idle time: heavy-tail
– # embedded objects: geometric (measurements e.g. mean 5)
– Object size: heavy-tailed
Page 14Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Content1. Performance & Network Planning
• Performance Impacting Factors, circuit switched planning approaches, packets switched planning
2. IP Quality of service and performance optimizations• Basic methods, implementation approaches• Protocol Enhancements (RoHC)
3. Session Initiation Protocol (SIP)• Architectures & Entities• Methods
4. IP based multimedia subsystems (IMS)• Architecture & components• Registration & Call Routing
5. Services6. Outlook: Beyond 3G Networks
Page 15Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IP QoS Solution I: Over-Provisioning
• Design network to be able to deal with worst-case traffic scenario• Advantage:
– no impact on architecture, protocols and user equipment– simplicity
• Problems:– Traffic depends on number of active users, user mobility, type of
application, daily utilization profile difficult forecasting– Data traffic tends to be very bursty (even `self-similar´)
waste of resources if planned for worst-case scenario can be very expensive
– Unforseeable events can occur (new applications; changes in user behavior, e.g. always-on)
Page 16Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
QoS Solutions II: DiffServ• Basic Idea: reduce queueing delay/loss for critical traffic by preferential
treatment at routers improve per-hop transmission behavior
• Packets marked by DiffServ Code Points (DSCPs, 6bit)
• Various scheduling disciplines at routers possible (e.g. static priority, weighted fair queueing)
• Advantage: Simple and scalable
• Problem: No performance guarantees unless used in conjunction with connection admission and traffic shaping/policing at ingress routers
SLA
CustomerNetwork
CustomerNetwork
SLA
SLA DiffServDomain
Boundary Router
Host
EdgeRouter SLA: Service Level Agreement
Page 17Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
QoS Solutions III: IntServ/RSVP• Fundamental Idea: Reserve necessary resources for each traffic flow along its
transmission path, which requires:
– Connection Admission Control (CAC): traffic specification + info about available resources at router admission decision (if no, then re-routing)
– Packet Classification: which flow does it belong to?
– Packet Scheduling: make sure, flow obtains resources as specified
Page 18Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
QoS Solutions III: IntServ/RSVP (cont`d)• Signalling by Resource Reservation Protocol (RSVP)
– Path Message: sender initiated, description of traffic parameters and path
– Resv Message: receiver initiated, causes connection admission/reservation along path; specifies QoS parameters
– Other messages for reservation teardown and error treatment– Soft-State concept: periodic refresh of reservation required
• Advantages:– Fine Granularity: per flow treatment, flexible set of QoS parameters– Able to provide QoS guarantees (if admission, classification,
scheduling is performed correctly)• Disadvantages
– Scalability problem: management of state for each single flow– Complexity (already connection admission can be complex, e.g.
effective bandwidths, etc.)
Page 19Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Protocol Enhancements: Motivation
• Wireless links tend to show poor performance– Large delays– Low throughput– Bit errors / packet losses due to radio transmission
• Protocols in IP family not originally designed for such links– Increased volume due to headers– Deficiencies of TCP flow control– ... many more (e.g. applications HTTPWAP)
• Protocol Enhancements are required, two examples discussed here– Robust Header Compression (RoHC)– Enhancements for Wireless TCP
Page 20Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Robust Header Compression (RoHC)• Motivation
– IP voice packets: header 40/60Bytes, average payload 25Bytes
– TCP ACK packets: header 40/60 Bytes, payload often 0Bytes
• Data in many header fields …
– … hardly ever changes e.g. source/destination address within same IP flow
– … or changes in a regular pattern
• Idea: reduce header length by compression, e.g.
– differential encoding of fields
– and/or variations of Huffman compression
• Compression can be applied to several protocol headers, e.g. RTP/UDP/IP
Page 21Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Robust Header Compression (RoHC)
• Synchronized compression context required in compressor and decompressor
• Lost packets Synchronization disturbed Additional mechanisms for context synchronisation required: Robustness
– Error detection by Cyclic Redundancy Codes (CRC)
– Loss detection through sequence numbers
Reduced compression efficiency price for error robustness
• Current RoHC methods: 40 Bytes RTP/UDP/IP header on average 1 or 2 bytes
Page 22Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
RoHC in UMTS
• RoHC optional part of Packet Data Convergence Protocol (PDCP) headers compressed only over radio link (RNC-UE)
• In principle compression already in GGSN possible, but– Flow identification/separation necessary– Large number of flows (up to 104 active flows)
L1
RLC
PDCP
MAC
IPv4 or v6
Application
L1
RLC
PDCP
MAC
ATM
UDP/IPv4 or v6
GTP‑U
AAL5
Relay
L1
UDP/IPv4 or v6
L2
GTP‑U
IPv4 or v6
3G‑SGSNUTRANMS
Iu-PSUu Gn Gi
3G‑GGSN
ATM
UDP/IPv4 or v6
GTP‑U
AAL5
L1
UDP/IPv4 or v6
GTP‑U
L2
Relay
L1
L2
IPv4 or v6
Page 23Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Content1. Performance & Network Planning
• Performance Impacting Factors, circuit switched planning approaches, packets switched planning
2. IP Quality of service and performance optimizations• Basic methods, implementation approaches• Protocol Enhancements (RoHC)
3. Session Initiation Protocol (SIP)• Architectures & Entities• Methods
4. IP based multimedia subsystems (IMS)• Architecture & components• Registration & Call Routing
5. Services6. Outlook: Beyond 3G Networks
Page 24Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Session Initiation Protocol -- SIP
SIP: Application layer signalling protocol (RFC 3261) Provides call control for multi-media services
initiation, modification, and termination of sessions terminal-type negotiation and selections call holding, forwarding, forking, transfer media type negotiation (also mid-call changes) using Session Description Protocol (SDP)
Provides personal mobility support Independent of transport protocols (TCP, UDP, SCTP,…) ASCII format SIP headers Separation of call signalling and data stream
Application types/examples: Interactive Voice over IP (VoIP) Multimedia conferences (multi-party, e.g. voice & video) Instant messaging Presence service Support of location-based services
Page 25Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP – Basic messages
• Selected Requests (Methods)– INVITE: initiate call– ACK: confirm final response (after ‘invite’)– BYE: terminate call– CANCEL: cancel pending requests– OPTIONS: queries features supported by
other side– REGISTER: register with location service
• Responses– 1xx Intermediate results
e.g. 180 Ringing– 2xx Successful Responses
e.g. 200 OK– 3xx Redirections
e.g. 302 Moved Temporarily– 4xx Request Failures– 5xx Server Failures– 6xx Global Errors
Page 26Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP Addressing and header formatAddressing:• Addresses specified SIP URL, in the format: user@host. • Examples of SIP URLs:
• sip:[email protected]• sip:[email protected]• sip:[email protected]
INVITE sip:[email protected] SIP/2.0Via: SIP/2.0/UDP 192.168.6.21:5060From: sip:[email protected]: <sip:[email protected]>Call-ID: [email protected]: 100 INVITEExpires: 180User-Agent: Cisco IP Phone/ Rev. 1/ SIP enabledAccept: application/sdpContact: sip:[email protected]:5060Content-Type: application/sdp
• Example: SIP Header
Page 27Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP: Architecture & Entities
User agent: An application program which initiates SIP requests (User agent client) and also acts upon (accepts, rejects or re-directs) incoming SIP requests (User agent server)
Location server provides SIP redirect or proxy servers information about a callee's possible location(s).
Proxy server takes requests on behalf other user agents or servers and forwards them to the next hop.
Redirect server accepts a SIP request, maps the address into zero or more new addresses and returns these addresses to the client. Unlike a proxy server, it does not initiate its own SIP request.
Registrar is a server that accepts REGISTER requests. A registrar is typically co-located with a proxy or redirect server and may offer location services.
Redirect Server
Location Server
Registrar Server
User Agent Proxy ServerProxy Server User Agent
Page 28Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP Call Signalling: Example
302 (Moved Temporarily)
INVITE
200 (OK)200 (OK)
ACK
INVITE
180 (Ringing)180 (Ringing)180 (Ringing)
200 (OK)ACKACK ACK
RTP MEDIA PATH
BYEBYE BYE
200 (OK)200 (OK) 200 (OK)Call Teardown
MediaPath
Call Setup
INVITE
Location/Redirect ServerProxy Server Proxy Server User AgentUser AgentINVITE
Page 29Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP: Separation of signalling and data
• Route of SIP messages (proxy chain) different than media stream route:
Potential Problems with Firewalls & NATs
Page 30Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP: Mobility support
User Mobility (change of terminal)• Registration via SIP ‘REGISTER’• mid-session mobility (application mobility):
call transfer, SIP method ‘REFER’ (RFC3515)
Host Mobility (change of IP address)• Pre-call: re-register, routing of ‘INVITE’ based
on SIP-URL• mid-call: re-invite
Page 31Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP: additional topics
Not touched in this lecture, see IETF SIP WG:• Multitude of SIP extensions: new methods (e.g. instant messages)• SIP over NAT/FW• Authentication and security aspects• Support of location based services• Discovery of SIP entities (e.g. DNS SRV records)• Service Discovery (e.g. SLP)• Reliability aspects of SIP-based call control
Page 32Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Content1. Performance & Network Planning
• Performance Impacting Factors, circuit switched planning approaches, packets switched planning
2. IP Quality of service and performance optimizations• Basic methods, implementation approaches• Protocol Enhancements (RoHC)
3. Session Initiation Protocol (SIP)• Architectures & Entities• Methods
4. IP based multimedia subsystems (IMS)• Architecture & components• Registration & Call Routing
5. Services6. Outlook: Beyond 3G Networks
Page 33Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IP based Multimedia Subsystem (IMS)
Additional domain in UMTS Rel. 5, based on Packet-switched domainEstablishment and Control of IP based multimedia calls based on SIP
Standardized interfaces to applicationsAuthentication and authorisation of service accessService based chargingQoS controlGlobal roaming and access to home services
Originally planned to be based on IPv6‘Network centric’ approach (as opposed to IETF SIP)In principle access independent (e.g. also WLAN access)No Network layer mobility support in IMS (mobility via SIP or in access networks)
Page 34Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP
Network Entities and Protocols
IM SubsystemApplicationsand
Services
MultimediaIP
Networks
CS Domain-or-
PSTN-or-
Legacy-or-
External
PS Domain
HSS
R-SGW
CSCF
CSCF
GGSN
MRF-CSCP
MGCF
MGW
SGSN
Cx
Sh
Sc
Gr
Mm
Mw
Mc
Gc
Mg
Gn
BGCF
T-SGW
BGCFMi
GoGm
SLF
Dx
AS
AlternativeAccess Networks
„Gi-Cloud“
PCF
OSA-SCS
IM-SSF
MRF-PMp
Sr
ISC
SIPSI
P
?
?
Dia
met
er
H248
SIP
H248
CO
PS
TCP/IP/UDP/RTP/…
SIP
?
MAP
CAP SIP
SIP
Mj
SIP TCP UDP
HTTP Others
? ?
SIP
?
R-SGW
CA
PO
SA
UE
UTRANMT TE
Uu IuR
GERAN
Mr
SIP Mk
Page 35Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Network Entities
• CSCF (Call State/Service Control Function)• PCF (Policy Control Function)• HSS (Home Subscriber Service)• SLF (Subscription Locator Function)• MRF (Multimedia Resource Function)• BGCF (Breakout Gateway Control Function)• MGCF (Median Gateway Control Function)• MGW (Media Gateway)• T-SGW (Transport Signaling Gateway)• R-SGW (Roaming Signaling Gateway)• AS (Application Server)• SCP (Service Content Provider)• IM-SSF (Service Switching Function)• OSA-SCS (Service Capability Server)
Additionally:- Charging Entities- Security Entities- Lawful Interception- Firewalls- DNS, DHCP, TRIP, …- QoS Entities- OAM and NM- …
Page 36Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IMS: Important Network ElementsHSS : Home Subscriber ServiceDatabase for subscriber related information• Identification (SIP, Mail, E.164, Label, IMSI, ...)• Location management (P-CSCF, S-CSCF, IP address)• List of authorized services, List of subscribed services• Quintuplets for Security
Proxy Call State Control Function (P-CSCF)First contact point of an operator‘s network (for the mobile terminal)• Forwarding of SIP messages between terminal and core network• Generation of charging records• Translation of IDs other than SIP URIs into SIP URIs
(e.g. E.164 numbers)• Termination of confidentiality and integrity, Lawful interception• Authorisation of bearer resources and QoS management• Detection of emergency calls and selection of a emergency S-CSCF• Translation of SIP URIs for local services• SIP header compression
Page 37Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IMS: Important Network Elements (cntd.)Interrogating Call State Control Function (I-CSCF)First contact point of an operator‘s network (for other operators)• Forwarding of SIP messages (proxy functionality)• Assignment of a S-CSCF
– during registration and during invite (for services for not registered subscribers)• Generation of charging records• Hiding of internal network configuration/capacity/topology
Serving Call State Control Function (S-CSCF)Performs session control and service triggering• Acts as a registrar according to RFC2543• May behave as a Proxy Server as defined in RFC2543, i.e. it accepts requests and services them
internally or forwards them on, possibly after translation.• May behave as a User Agent as defined in RFC2543, i.e. it may terminate and independently
generate SIP transactions.• Interaction with service platform(s), provides endpoints with service event related information • Authentication (based on quintuplets from HSS), Generation of charging records
Page 38Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Levels of Registration
UE xGSN
Visited Network Home Network
UMS
CSCFDHCP AS
HLR
Bearer Level
IM Subsystem
Application?
DHCP
CSCF HSS
Page 39Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Registration in a Roaming Scenario
Home Network of MS B
Network visited by MS B
MS B
P-CSCF-B
S-CSCF-B
2
1
Home Network of MS A
Network visited by MS A
MS A
P-CSCF-A
S-CSCF-A
REG
ISTE
R
I-CSCF-A
HSS-A User Profile
1
2
4
5
REG
ISTE
R
I-CSCF-A4
HSS-AUser Profile
5
Page 40Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Routing of Mobile-To-Mobile Calls
Home Network of MS A
Network visited by MS A
Home Network of MS B
Network visited by MS B
MS A MS B
P-CSCF-A
I-CSCF-B
P-CSCF-B
HSS-B
S-CSCF-A S-CSCF-B
REG
ISTE
R
User Profile
1 2
34
5
6
7
INVI
TE
Call C
ontro
l
REG
ISTE
R
I-CSCF-A
HSS-A User Profile
Page 41Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Foreign Network
Routing of Mobile Calls to CS or PSTN (3GPP)
Home Network of MS A
Network visited by MS A
MS A
PSTN
P-CSCF-A
I-CSCF-A
HSS-A
User Profile
S-CSCF A
MGCF-B T-SGW-B
MGW-B
I-CSCF-B
BGCF-BBGCF-ARE
GIS
TER
INVI
TE
Call C
ontro
l
GatewayControl
1 2
3
4
5
7
User Profile
A
B
6
Page 42Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
SIP in IMS• Mandatory existence of P-CSCF as first point of contact• Network initiated call release (e.g. due to missing coverage or administrative reasons)
– Proxies are able to send BYE
• Network Control of Media Types– P/S-CSCF checks the SDP in the SIP body– If SDP contains invalid parameters (e.g. not supported codecs), P/S-CSCF rejects the SIP request by sending a
488 (“not acceptable here”) response that contains a SDP body indicating parameters that would be acceptable by the network
• Network Hiding (Encryption of Route and Via Headers)• Additional Signaling Information
– For example Cell-ID, Mobile Network/Country Code, Charging-IDs – Information transported P-header based solution
• Compression– SIP Compression is mandatory as radio interface is a scarce resource– Compression / decompression of SIP will be performed by the UE and the P-CSCF
• Authentication & Integrity protection– S-CSCF performs the Authentication using AKA – P-CSCF checks the integrity of messages received via the air interface via IPsec ESP
Page 43Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IMS: Services are Home Controlled
3rd Party ServiceProvider
Visited Network Home Network
UEServingCSCF
ApplicationServer
ProxyCSCF
ApplicationServer
SIP
ISC
SIPSIP
ApplicationServer
The Serving CSCF (S-CSCF) is located in the Home Network The Visited Network only provides a proxy (P-CSCF): all calls are always first
routed to the Home Network.
??
Page 44Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
IM Core Network Subsystem
IMS Security Architecture
HSS
I-CSCF S-CSCF
Home / Serving Network
P-CSCF
Visited / Home Network
ISIM
UA
UE
Mutualauthentication
IMS AKA
IPSec:IntegrityProtection
IPSec: Confidentiality and Integrity Protection
IPSec: Confidentiality and Integrity Protection
Page 45Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Entertainment
•m-Gaming
•Gambling
•Audio
•Video
•Unified Messaging
•MMS
•Chat
•Conferencing
•Voice over IP
•Buddy list
•Presence configuration
•Availability configuration
Information
•Dynamic Info Svcs.
•Static Info Svcs.
Commerce
•m-Banking
•m-Shopping
•m-ticketing & reservations
•m-advertisement
End User Services: Categorization
Communication
Page 46Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Service Market Analysis
Willing to Use (W2U) / Willing to Pay (W2P)
Source: Adopted from Siemens End-User Survey 2000
Commerce Entertainment
Communication Information
Commerce27 %
Entertainment14 %
Information29 %
Communication30 %
Service Desirability (W2U)
Commerce Entertainment
Communication Information
Commerce12 %
Information3 %
Communication57 %
Entertainment28 %
Source: Durlacher UMTS Report
Service Revenue Potential (W2P)
Page 47Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Within the next six years data and multimedia traffic will overrule voice
In 2008 Multimedia Communication will account for ¼ of mobile traffic
Mbit/
User/
Month
Browsing & Download
Messaging
Real-Time Multimedia
Voice (Minutes of Use x 9,6 kb/s)50
100
150
200
250
300
350
2003 2004 2005 2006 2007 2008
0
Prediction: services in mobile NWs
Page 48Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Summary1. Performance & Network Planning
• Performance Impacting Factors, circuit switched planning approaches, packets switched planning
2. IP Quality of service and performance optimizations• Basic methods, implementation approaches• Protocol Enhancements (RoHC)
3. Session Initiation Protocol (SIP)• Architectures & Entities• Methods
4. IP based multimedia subsystems (IMS)• Architecture & components• Registration & Call Routing
5. Services6. Outlook: Beyond 3G Networks
Page 49Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Outlook: Beyond 3G networks• Unifies different
access technologies• IP as convergence
layer• Mobility support on
the network layer• Ad-hoc networks can
extend geographic reach of cellular wireless technologies
• Personal Area Networks (PAN)
• Ubiquitous Computing
Services andapplications
IP based core network
IMT-2000UMTS
WLANtype
cellularGSM
short range
connectivity
WirelinexDSL
otherentities
DABDVB
return channel:e.g. GSM
download channel
New radiointerface
Page 50Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Problem: IP address identifies host as well as topological locationReason: IP Routing:
– Routes selected based on IP destination address– network prefix (e.g. 129.13.42) determines physical subnet– change of physical subnet change of IP address to have a topological correct address
• Solution? Host-based routing: Specific routes to each host– Handover change of all routing table entries in each (!) router– Scalability & performance problem
• Solution? Obtain new IP-address at hand-over– Problem: how to identify host after handover? DNS update performance/scalability problem– Higher protocol layers (TCP/UDP/application) need to ‘handle’ changing IP address
Development of mobile IP
Mobile IP Motivation: Host mobility & Routing
Subnet A
Subnet BIP network
Mobile Node
Page 51Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Mobile IP: Principles & Terminology
Underlying Approach: separate host identifier and location identifier maintain multiple IP addresses for mobile host
Terminology:• Mobile Node (MN) with fixed IP address IP1 (home address)• Home Network: subnet that contains IP1
• Home Agent (HA): node in home network, responsible for packet forwarding to MN• Visited Network: new subnet after roaming / handover• Care-of Address (CoA): temporary IP address within visited network• Foreign Agent (FA): node in visited network, responsible for packet forwarding to CoA
Home network
Visited network
IP network
Mobile Node Home Address IP1
HA
FA Home Address IP1
Care of Address: CoA1Correspondent Node
Page 52Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Home Network
Mobile IP: Tunneling &Triangle Routing
CN sends packets to the MN using its Home Address IP1
HA tunnels them to FA, using CoA1; FA forwards them to MN
MN sends packets back to the CN using IP2 (without any tunneling)
Home Agent needs to contain mapping of care-of address to home address (location register)
Mobile NodeIP1, CoA1
Home Agent
Subnet
Correspondent Node (CN) IP2
Visited Network
FA
IP1
CoA1
IP2
Source: Mobile IPv4 illustrated
Page 53Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Mobile IP: Agent Discovery & Registration
• Mobile Node finds out about FA through Agent Advertisements– FAs broadcast Advertisements in periodic intervals– Advertisements can be triggered by an Agent Solicitation from the MN
• Care of Address of the MN is determined, either– Dynamically, e.g. using Dynamic Host Configuration Protocol (DHCP)– Or: use IP address of FA as CoA
• MN registers at FA and HA: Registration Request & Reply– MN signals COA to the HA via the FA– HA acknowledges via FA to MN
• Registration with old FA simply expires (limited life-time, soft-state)
FAHA MN
[Agent Solicitation] (opt.)
Agent Advertisement
Registration Request
Registration ReplyTime
Obtain c/o address
Page 54Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
type = 16R: registration requiredB: busy, no more registrationsH: home agentF: foreign agentM: minimal encapsulationG: GRE encapsulationr: =0, ignored (former Van Jacobson compression)T: FA supports reverse tunnelingreserved: =0, ignored
MIP messages:Agent advertisement
preference level 1router address 1
#addressestype
addr. size lifetimechecksum
COA 1COA 2
type = 16 sequence numberlength
0 7 8 15 16 312423code
preference level 2router address 2
. . .
registration lifetime
. . .
R B H F M G r reservedT
Procedure:
• HA and FA periodically broadcast advertisement messages into their subnets
• MN listens to these messages and detects, if it is in the home or a (new?) foreign network
• when new foreign network: MN reads a COA from the advertisement (opt.)
ICMP Router Discovery extension:
Page 55Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
MIP messages: registration request & reply
home agenthome address
type = 1 lifetime0 7 8 15 16 312423
T x
identification
COA
extensions . . .
S B D MG rS: simultaneous bindingsB: broadcast datagramsD: decapsulation by MNM mininal encapsulationG: GRE encapsulationr: =0, ignoredT: reverse tunneling requestedx: =0, ignored
Registration Request (via UDP)
home agenthome address
type = 3 lifetime0 7 8 15 16 31
code
identification
extensions . . .
Registration Reply (UDP)
Example codes:registration successful• 0 registration accepted• 1 registration accepted, but simultaneous mobility bindings unsupportedregistration denied by FA•65 administratively prohibited•66 insufficient resources•67 mobile node failed authentication
•68 home agent failed authentication•69 requested Lifetime too longregistration denied by HA•129 administratively prohibited•131 mobile node failed authentication•133 registration Identification mismatch•135 too many simultaneous mobility bindings
Page 56Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
MIP: Care-of addressesMN obtains local care-of address either• from FA Advertisement (see before)
• Or via Dynamic Host Configuration Protocol (DHCP)– supplies systems with all necessary information, such as IP address, DNS server
address, domain name, subnet mask, default router etc.– Client/Server-Model: client sends request via L2 broadcast
time
server(not selected)
client server(selected)
initialization
collection of replies
selection of configuration
initialization completed
confirmation ofconfiguration
determine the configuration
DHCPDISCOVER
DHCPOFFER
DHCPREQUEST(reject)
DHCPACK
DHCPDISCOVER
DHCPOFFER
DHCPREQUEST(options)
determine the configuration
Page 57Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
The future of mobile networks
“Much of the initial enthusiasm for the concept appears to have evaporated and the original launch target of autumn this year has been slipping. When the government asked companies to apply for licences, international consortia rushed to compete.
(…) Since then, the economy has sunk into recession, forecasts of the number of subscribers have been scaled down and the need for heavy investment has scared many of the original shareholders.”
Financial Times: September 1992 “The Future of GSM Mobile Communications”
Page 58Hans Peter Schwefel
PhD Course: UMTS Lecture 2, Fall03
Acknowledgements (Lectures 1 & 2)• Tutorial: IP Technology in 3rd Generation mobile networks,
Siemens AG (J. Kross, L. Smith, H. Schwefel)• Lecture notes: Wireless Data Communication, MM5,
www.kom.auc.dk/~hps/teaching• Tutorial: Voice over IP Protocols – An Overview, www.vovida.org
• Various 3GPP slide-sets• Siemens ICM N PG U SE and Siemens CT IC 3
Other References• IETF (www.ietf.org)
– WGs: MMUSIC (old), SIP
• 3GPP: www.3gpp.org