wireless ip multimedia
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Wireless IP Multimedia. Henning Schulzrinne Columbia University MOBICOM Tutorial, September 2002. Types of wireless multimedia applications streaming interactive object delivery Properties of multimedia content loss resiliency delay reordering 3G and WLAN MM-related channel properties - PowerPoint PPT PresentationTRANSCRIPT
Wireless IP Multimedia
Henning SchulzrinneColumbia University
MOBICOM Tutorial, September 2002
April 21, 2023 2
Overview Types of wireless
multimedia applications– streaming– interactive– object delivery
Properties of multimedia content– loss resiliency– delay– reordering
3G and WLAN MM-related channel properties– effective bandwidth– packet loss– delay
Header and signaling compression– cRTP– ROHC– signaling compression
Packet FEC UMTS multimedia
subsystem (IMS)– QoS– Session setup
Fast handoff mechanisms
Multimodal networking
April 21, 2023 3
Types of wireless multimedia applications
Interactive– VoIP– multimedia conferences– multiplayer games
Streaming– video/audio on demand– broadcast TV/radio– may be cached at various places, including end system
Object retrieval– peer-to-peer– user may be waiting for result
Messaging– store-and-forward (e.g., MMS)– can be batched
April 21, 2023 4
IETF (multimedia) protocolsMedia Transport
App
lica
tion
Ker
nel
Phy
sica
lN
etw
ork
H.323 SIP RTSP RSVP RTCPRTP
TCP UDP
IPv4, IPv6, IP Multicast
PPP AAL3/4 AAL5 PPP
SONET ATM Ethernet CDMA 1XRTT/GPRS
Signaling media encap(H.261. MPEG)
ICMP IGMP
SAP
802.11b
DNSLDAP
MIP MIP-LR
CIP
SDP
MIPv6
MGCP
IDMP
DHCPP
Heterogeneous Access
April 21, 2023 5
Common wired & wireless audio codecs
codec name standards org.
samplin
g rate (Hz)
frame size
bit rate (kb/s)
G.711 (µ/A-law) ITU 8,000 any 64
G.723.1 ITU 8,000 20 ms 5.3, 6.3
G.729 (CS-ACELP) ITU (1996)
8,000 10 ms 8
AMR(adaptive multi-rate)
ETSI 26.090(1999)
8,000 20 ms 4.75 – 12.2 (8)6.7: PDC-EFR7.4: IS 64112.2: GSM-EFR
GSM-HR GSM 06.20
8,000 20 ms 5.6
GSM-FR GSM 06.10
8,000 20 ms 13
AMR-WB (wideband)
ETSI 16,000
20 ms 6.6 – 23.85 (9)
April 21, 2023 6
Audio codecs, cont'd.codec name standard
s org.sampli
ng rate (Hz)
frame size
bit rate (kb/s)
EVRC (RCELP) TIA/EIA (1996)
8,000 20 ms 8.55, 4, 0.8
G.726 (ADPCM) ITU 8,000 sample 16, 24, 32, 40
G.728 (LD-CELP) ITU 8,000 20 ms 16
April 21, 2023 7
Audio codecs MP3 and AAC: delay > 300 ms unsuitable
for interactive applications GSM and AMR are speech (voiceband) codecs
3.4 kHz analog designed for circuit networks with non-zero BER
Wideband = split into two bands, code separately conferencing
AMR is not variable-rate (dependent on speech content)
receiver sends Codec Mode Request (CMR) to request different codec, piggy-backed on reverse direction
trade-off codec vs. error correction
April 21, 2023 8
Audio codecs Typically, have algorithmic look-ahead of
about 5 ms additional delay– G.728 has 0.625 ms look-ahead
AMR complexity: 15-25 MIPS, 5.3 KB RAM
4 6 8 10 12 14 16 18 20 22 24
G.723.1
G.729
G.729A
AMR-NB
AMR-WB
original
www.voiceage.com
April 21, 2023 9
Audio codecs - silence
Almost all audio codecs support Voice Activity Detection (VAD) + comfort noise (CN)– comfort noise: rough approximation in
energy and spectrum avoid "dead line" effect
– G.729B– AMR built-in: CN periodically in Silence
Indicator (SID) frames = discontinuous transmission (DTX) saves battery power
– or source controlled rate (SCR)
April 21, 2023 10
Audio codecs - silence
silence periods depend on– background noise– word vs. sentence vs. alternate
speaker particularly useful for conferences
– small ratio of speakers to participants– avoid additive background noise
April 21, 2023 11
Video codecs
MotionEstimation
&Compensation
MotionEstimation
&Compensation
Transform,Quantization, Zig-Zag Scan & Run-Length Encoding
Transform,Quantization, Zig-Zag Scan & Run-Length Encoding
SymbolEncoder
SymbolEncoder
Frames ofDigital Video
Bit Stream
common code words shorter symbolsHuffman, arithmetic coding
e.g., DCT: spatial frequency
Quantization changes representationsize for each symbol adjust rate/quality trade-off
Run-length encoding: long runs of zeros run-length symbol
predict currentframe from previous
JPEG
MPEG, H.26xcourtesyM. Khansari
April 21, 2023 12
History of video codecs
1990 1996 20021992 1994 1998 2000
H.263LH.263L
H.263++H.263++
H.263+H.263+
H.263H.263H.261H.261
MPEG 7MPEG 7
MPEG 4MPEG 4
MPEG 2MPEG 2
MPEG 1MPEG 1
ISO
ITU
-T
courtesyM. Khansari
April 21, 2023 13
H.263L example
64 kb/s, 15 fps
courtesy of Siemens CT
April 21, 2023 14
Delay requirements In many cases, channel is delay constrained:
– ARQ mechanisms– FEC– low bandwidths
ITU G.114 Recommendation:– 0..150 ms one way delay: acceptable to most users– 150..400 ms: acceptable with impairments
Other limits:– telnet/ssh limit ~ 100-200 ms [Shneiderman 1984,
Long 1976]?– reaction time 1-2 s for human in loop [Miller 1968]:
• web browser response• VCR control for streaming media• ringback delay for call setup• can often be bridged by application design
April 21, 2023 15
802.11 architecture
STASTA
STA STA
STASTASTA STA
APAP
ESS
BSS
BSSBSS
BSS
Existing Wired LAN
Infrastructure Network
Ad Hoc Network
Ad Hoc Network
Mustafa Ergen
April 21, 2023 16
802.11b hand-offKanter, Maguire, Escudero-Pascual, 2001
April 21, 2023 17
802.11 delay
Data ACK
(short IFS)
DIFS SIFS DIFS
idle slots
channel is busy idle
slots
time
DIFS SIFS SIFS SIFS DIFS
idle slots
idle slots
RTS CTS Data ACK
time
M. Zukerman
IFS (µs)
FHSS
DSSS OFDM
SIFS 28 10 13
PIFS 78 30 19
DIFS 128 50 25
(DCF interframe space)
April 21, 2023 18
802.11 delay
802.11b: 192 bit PHY headers 192 µs (sent at 1 Mb/s)
802.11a: 60 µs three MAC modes:
– DCF– DCF + RTS– PCF: AP-mode only
802.11 1, 2 Mb/s DSSS
802.11b
11 Mb/s FHSS, DSSS
802.11a
2, 11, 24, 54 Mb/s
OFDM
April 21, 2023 19
802.11 delay
Throughput
Mea
n da
ta f
ram
e de
lay
(mse
c) Payload:512 bits
2430 bits4348 bits8184 bits
April 21, 2023 20
802.11 delay
Throughput
Mea
n m
essa
ge d
elay
(m
sec)
Hyper-geometricGeometricDual fixedFixed
April 21, 2023 21
802.11a delay for VoIP
April 21, 2023 22
802.11b channel access delay
Köpsel/Wolisz
• 12 mobile data nodes, 4 mobile with on/off audio• 6 Mb/s load
April 21, 2023 23
802.11b VoIP delay Köpsel/Wolisz WoWMoM 2001: add priority and
PCF enhancement to improve voice delay
DCF
Köpsel/Wolisz
April 21, 2023 24
802.11b – PCF+priority
Köpsel/Wolisz
poll only stations with audio data
move audio flows from PCF to DCF and back after talkspurts
• IEEE 802.11 TGe working on enhancements for MAC (PCF and DCF)• multiple priority queues
April 21, 2023 25
802.11e = enhanced DCF
Mustafa Ergen
HC hybrid controller
TC traffic categories
AIFS arbitration IFS
TXOP transmission opportunity
April 21, 2023 26
802.11e back-off
April 21, 2023 27
Metric of VoIP quality
Mean Opinion Score (MOS) [ITU P.830]– Obtained via human-based listening
tests– Listening (MOS) vs. conversational
(MOSc)
Grade
Quality
5 Excellent
4 Good
3 Fair
2 Poor
1 Bad 1.5
2
2.5
3
3.5
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
iLBC 14kb/sG.729 8kb/s
G.723.1 6.3kb/s
April 21, 2023 28
FEC and IP header overhead
An (n,k) FEC code has (n-k)/k overhead
Typical IP/UDP/RTP header is 40 bytes
codec media pkt size (T=30ms)
rmedia rIP
iLBC(4,2) FEC
54 bytes 14.4 kb/s
25.1 kb/s
108 bytes 28.8 kb/s
39.5 kb/s
G.729(4,2) FEC
30 bytes 8 kb/s 18.7 kb/s
60 bytes 16 kb/s 26.7 kb/s
G.723.1(4,2) FEC
24 bytes 6.4 kb/s 17.1 kb/s
48 bytes 12.8 kb/s
23.5 kb/s
April 21, 2023 29
Predicting MOS in VoIP
The E-model: an alternative to human-based MOS estimation– Do need a first-time calibration from an
existing human MOS-loss curve In VoIP, the E-model simplifies to two
main factors: loss (Ie) and delay (Id) A gross score R is computed and
translated to MOS. Loss-to-Ie mapping is codec-
dependent and calibrated
April 21, 2023 30
Predicting MOS in VoIP, contd
Example mappings– From loss and
delay to their impairment scores and to MOS
10
15
20
25
30
35
40
45
50
0 0.03 0.06 0.09 0.12 0.15 0.18
Ie (l
oss
impa
irmen
t)
average loss probability
G.729 T=20ms random loss
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300 350 400
Id (d
elay
impa
irmen
t)
delay (ms)
E-model Id
0.5
1
1.5
2
2.5
3
3.5
4
4.5
20 40 60 80 100
MO
S
R value
R to MOS mapping
April 21, 2023 31
Predicting MOS under FEC Compute final loss probability pf after
FEC [Frossard 2001]– Bursty loss reduces FEC performance– Increasing the packet interval T makes
FEC more efficient under bursty loss [Jiang 2002]
Plug pf into the calibrated loss-to-Ie mapping
FEC delay is n*T for an (n,k) code Compute R value and translate to
MOS
April 21, 2023 32
Quality Evaluation of FEC vs. Codec Robustness
Codecs under evaluation– iLBC: a recent loss-robust codec proposed
in IETF; frame-independent coding– G.729: a near toll quality ITU codec– G.723.1: an ITU codec with even lower bit-
rate, but also slightly lower quality.
Utilize MOS curves from IETF presentations for FEC MOS estimation
Assume some loss burstiness (conditional loss probability of 30%)
Default packet interval T = 30ms
April 21, 2023 33
G.729+(5,3) FEC vs. iLBC Ignoring delay effect, a larger T improves
FEC efficiency and its quality When considering delay, however, using
a 60ms interval is overkill, due to higher FEC delay (5*60 = 300ms)
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.729+(5,3)G.729+(5,3),T=60ms
iLBC,no FEC 2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.729+(5,3)G.729+(5,3),T=60ms
iLBC, no FEC
April 21, 2023 34
G.729+(5,2) vs. iLBC+(3,2)
When iLBC also uses FEC, and still keeping similar gross bit-rate– G.729 still better, except for low loss
conditions when considering delay
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.729+(5,2)G.729+(5,2),T=60ms
iLBC+(3,2)2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.729+(5,2)G.729+(5,2),T=60ms
iLBC+(3,2) FEC
April 21, 2023 35
G.729+(7,2) vs. iLBC+(4,2)
Too much FEC redundancy (e.g., for G.729) very long FEC block and delay not always a good idea
iLBC wins in this case, when considering delay
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.729+(7,2)iLBC+(4,2)
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.729+(7,2)iLBC+(4,2)
April 21, 2023 36
G.729+(3,1) vs. iLBC+(4,2)
Using less FEC redundancy may actually help, if the FEC block is shorter
Now G.729 performs similar to iLBC
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.729+(3,1)iLBC+(4,2)
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.729+(3,1)iLBC+(4,2)
April 21, 2023 37
Comparison with G.723.1
MOS(G.723.1) < MOS(iLBC) at zero loss iLBC dominates more low loss areas compared
with G.729, whether delay is considered or not
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.723.1+(2,1)G.723.1+(2,1),T=60ms
iLBC, no FEC
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.723.1+(2,1)G.723.1+(2,1),T=60ms
iLBC,no FEC
April 21, 2023 38
G.723.1+(3,1) vs. iLBC+(3,2)
iLBC is still better for low loss G.723.1 wins for higher loss
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.723.1+(3,1)G.723.1+(3,1),T=60ms
iLBC+(3,2)2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.723.1+(3,1)G.723.1+(3,1),T=60ms
iLBC+(3,2)
April 21, 2023 39
G.723.1+(4,1) vs. iLBC+(4,2)
iLBC dominates in this case whether delay is considered or not,– (4,2) code already suffices for iLBC– (4,1) code’s performance essentially “saturates”
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S
average loss probability
G.723.1+(4,1)G.723.1+(4,1),T=60ms
iLBC+(4,2)2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
G.723.1+(4,1)G.723.1+(4,1),T=60ms
iLBC+(4,2)
April 21, 2023 40
The best of both worlds Observations, when considering delay:
– iLBC is usually preferred in low loss conditions– G.729 or G.723.1 + FEC better for high loss
Example: max bandwidth 14 kb/s– Consider delay impairment (use MOSc)
G.729+(5,3)
G.723.1+(2,1),T=60ms
iLBC
33.23.43.63.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
Max BW: 14 kb/s
2.82.62.42.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
iLBC,no FECG.729+(5,3)
G.723.1+(2,1),T=60ms
April 21, 2023 41
Max Bandwidth: 21-28 kb/siLBC
G.729+(5,2)
2.83
3.23.43.63.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
Max BW: 21 kb/s
2.62.4
G.729+(3,1)G.729+(5,2)
iLBC
33.23.43.63.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
Max BW: 28 kb/s
2.82.62.42.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
iLBC, no FECG.729+(3,1)G.729+(5,2)
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
iLBC, no FECG.729+(5,2)
April 21, 2023 42
Effect of max bandwidth on achievable quality
14 to 21 kb/s: significant improvement in MOSc
From 21 to 28 kb/s: marginal change due to increasing delay impairment by FEC
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 0.03 0.06 0.09 0.12 0.15
MO
S_c
average loss probability
Max BW: 14 kb/sMax BW: 21 kb/sMax BW: 28 kb/s
April 21, 2023 43
UMTS and 3G wireless Staged roll-out with "vintages" releases:
– Release 3 ("1999") GPRS data services• Multimedia messaging service (MMS) = SMS successor
~ MIME email• RAN via evolved CDMA
– Release 4: March 2001– Release 5: March-June 2002– Release 6: June 2003 all-IP network
Main future new features (affecting packet services): – All-IP transport in the Radio Access and Core Networks– Enhancements of services and service management– High-speed Downlink Packet Access (HSDPA)
• Introduces additional downlink channels:– High-Speed Downlink Shared Channel (HS-DSCH)– Shared Control Channels for HS-DSCH
April 21, 2023 44
UMTS
Follow-on to GSM, but WCDMA physical layer
new ($$$) spectrum around 2 GHz radio transmission modes:
– frequency division duplex (FDD): 2 x 60 MHz– time division duplex (TDD): 15 + 20 MHz
Chip rate 3.84 Mcps channel bandwidth 4.4 – 5 MHz
macrocell
2 km 144 kb/s
microcell
1 km 384 kb/s
picocell 60 m 2 Mb/s
April 21, 2023 45
1G-3G air interface3G/ IMT-2000 Capable
Existing Spectrum New Spectrum
IS-95-A/cdmaOne
IS-95-A/cdmaOne
IS-95-B/cdmaOne
IS-95-B/cdmaOne
IS-136TDMA
IS-136TDMA
136 HSEDGE
136 HSEDGE
GSMGSM
GSM GPRSGSM GPRS EDGEEDGE
WCDMAWCDMA
cdma2000 1X (1.25 MHz)
cdma2000 3X (5 MHz)
HSCSDHSCSD
1XEV DO: HDR (1.25 MHz)1XEV DO: HDR (1.25 MHz)
2G “2.5G”1G
AnalogAMPS
AnalogAMPS
TACSTACS
Ramjee
April 21, 2023 46
The mysterious 4G
Fixes everything that's wrong with 3G Convergence to IP model: treat radio
access as link layer that carries IP(v6) packets– not necessarily new radio channel
• no new spectrum available
all-IP radio access network (RAN) common mobility management
– AAA and roaming– user identifiers– roaming across wired networks
April 21, 2023 47
UMTS – 3GPP and 3GGP2
Divided regionally/historically:– both from ITU IMT-2000 initiative– GSM 3GPP (ETSI) = WCDMA– US (CDMA) 3gpp2 (TIA) =
CDMA2000 3GPP2: different PHY, but similar
applications (not completely specified)– cdma2000
April 21, 2023 48
UMTS
Node B
UE Applic.
PDCP
PHY
Iu Uu
GTP-U UDP
AAL5/ ATM
IP
RNC IP
TCP GGSN
GTP-U
SGSN
IP IP routing
UDP/ TCP
Gn/Gp
IP IP
IP TCP
IP server
IP
Gi
GTP-U
UDP
AAL5/ ATM
IP
GTP-U
UDP/ TCP
IP
GPRS IP backbone
Gn
Application
RLC MAC
Iu UP Iu UP
IP
PDCP RLC MAC
Iub
PHY AAL2/ ATM
PHY
AAL2/ ATM
FP FP
Radio Bearers
Logical channels
Transport channels
UTRAN Packet switched Core Network
Physical channels
Radio Access Bearers
W. Granzow
April 21, 2023 49
3GPP network architecture
DOCUMENTTYPE
TypeUnitOrDepartmentHereTypeYourNameHere TypeDateHere
Radio Access Network Core Network
IuUu
End userterminal
AS
Jalava
April 21, 2023 50
3GPP network architecture - gateways
Legacy MobileSignaling Networks
Roaming Signaling Gateway (R-SGW)
MsMh
HSS
PSTN/Legacy/External
MultimediaIP Networks
Gi
Gi
CSCF
MRF
CxMr
Gi
Mm
Media Gateway (MGW)
Media Gateway Control Function
(MGCF)
Transport Switching Gateway (T-SGW)
Mc (= H.248)
Gi
Mg
GGSN
Media Gateway (MGW)
SGSN
Alves
April 21, 2023 51
3GPP networks – call control
Gi
Call State Control Function (CSCF)
Multimedia Resource Function (MRF)
Cx
Mr
Gi
VHE / OSA
Application I/F
Gr
Home Subscriber
Server (HSS)
(=HLR + +)
Gc
CAP
SGSN GGSN
access
EIR
Gn
Gf
Iu
to other networks
Applications & Services
-View on CALL CONTROL -
Alves
April 21, 2023 52
UMTS network architecture
Node B
Radio networkSystem (RNS)
MSC/GSN
MSC Mobile Services Switching CenterGSN GPRS Support Node
Node B
Node B
RNC
Node BNode B
Node B
RNC
Node B
RNC Radio Network controllerNode B Base Node
W. Granzow
April 21, 2023 53
Aside: some 3G/UMTS terminology
CS circuit-switched
GERAN GSM/EDGE Radio Access Network
GGSN Gateway GPRS Support Node. A router between the GPRS network and an external network (i.e., the Internet).
PDP Packet Data Protocol
PDP context
A PDP connection between the UE and the GGSN.
PS packet-switched
SGSN Serving GPRS Support Node
UTRAN Universal Terrestrial Radio Access Network
See RFC 3114 for brief introduction.
April 21, 2023 54
UTRA transport channels categories
Common channels– Multiplexed users (user ID in the MAC header)
• Forward Access Channel (FACH)• Random Access Channel (RACH)• Common Packet Channel (CPCH)
Dedicated channels (DCH)– Assigned to a single user (identified by the spreading
code)
Shared channels – „Sharing“ of code resource by several users by fast
re-assignment scheduling• Downlink Shared Channel (DSCH)
April 21, 2023 55
1 radio frame (10 ms), 15*2560 chips (3.84 Mcps)
Slot iSlot 1 Slot 2 Slot 15time
frequency
5 MHz 5 MHz 5 MHz 5 MHz
Macrocell layersMicrocell
layer
Duplex distance, e.g. 190 MHz
Uplink Downlink
Transmission Format UTRA FDD
April 21, 2023 56
UMTS/3G QoS classes
conversational
voice, video conferencing
low delay, strict ordering
streaming video streaming modest delay, strict ordering
interactive web browsing, games
modest delay
background email download no delay guarantees
April 21, 2023 57
QoS class requirements
Excerpt from 3GPP TS 23.107:Traffic class Conversationa
lStreaming Interactive Background
Residual BER 5*10-2, 10-2, 5*10-3, 10-3, 10-4, 10-6
5*10-2, 10-2, 5*10-3, 10-3,
10-4, 10-5, 10-6
4*10-3, 10-5, 6*10-8
4*10-3, 10-5, 6*10-8
SDU error rate 10-2, 7*10-3, 10-3, 10-4, 10-5
10-1, 10-2, 7*10-3, 10-3,
10-4, 10-5
10-3, 10-4, 10-6 10-3, 10-4,
10-6
Transfer delay 100 ms 250 msGuaranteed bit rate
2,048 kb/s 2,048 kb/s
Traffic handling priority
1,2,3
Allocation/retention priority
1,2,3 1,2,3 1,2,3 1,2,3
April 21, 2023 58
GPRS delayGurtov, PWC 2001
April 21, 2023 59
UMTS transport
UUTTRRAANN UUMMTTSS//GGPPRRSSBBaacckkbboonnee
((IIPPvv44))
SGSN
GGSN
L1
RLC
PDCP
IP
TCP/UDP
Appl
RBS RNC
MAC
L1
RLC
MAC
PDCP GTP-U
Relay
L2/L1
UDP
IP
GTP-U GTP-U
Relay
L2/L1
UDP
IP
L2/L1
UDP
IP
L1
L2
L2/L1
UDP
IP
L1
IP
TCP/UDP
Appl
GTP-U
IP IP
L2
Gn/Gp GiIu-PSUuUE UTRAN SGSN GGSN Host
UE
EExxtteerrnnaallPPLLMMNNGp
GnHost
IIPPNNeettwwoorrkk
User level IP
Transport level IP
Iub
April 21, 2023 60
UMTS Release 4/5 Architecture
Kulkarni
April 21, 2023 61
QoS in UMTS Short term: signaling tell network elements about
QoS requirements– RSVP (IntServ)– DiffServ with DSCPs– PDP context
Longer term: provisioning allocate resources to QoS classes– low network utilization (overprovisioning)– DiffServ– IntServ (possibly for DiffServ classes, RFC xxxx)– MPLS
Mechanisms can be heterogeneous– DSCP translation– localized RSVP
April 21, 2023 62
QoS signaling in UMTS UMTS R5: two end-to-end QoS signaling scenarios QoS provisioning left vague RSVP currently not in standard
– additional scenario featuring RSVP may be added to a later release of the standard
QoS connected to application layer signaling (SIP)SIP - Session Initiation Protocol– necessary for IP telephony, not streaming or data– SIP allows applications to agree on address, port,
codec, ...– standardized by IETF– but UMTS-specific SIP dialect
• additional functionality compared to IETF SIP
April 21, 2023 63
Session setup: SIP
[email protected]: 128.59.16.1
INVITE
REGISTER
BYE
INVITE sip:[email protected] SIP/2.0Via: SIP/2.0/UDP pc33.atlanta.com ;branch=z9Max-Forwards: 70To: Bob <sip:[email protected]>From: Alice <sip:[email protected]> ;tag=1928301774Call-ID: [email protected]: 314159 INVITEContact: <sip:[email protected]>Content-Type: application/sdpContent-Length: 142
April 21, 2023 64
Session setup: SIP Creates, modifies,
terminates sessions sessions = audio, video,
text messages, … IETF RFC 3261-3266 UTF-8 text, similar to HTTP
– request line– headers– body (= session description
~ SDP), not touched by proxies
URLs for addresses– sip:[email protected]– tel:+1-212-555-1234
Client 2Client 1
INVITEINVITE
100 Trying
180 Ringing
180 Ringing
200 OK
200 OK
ACK
ACK
Media streams
BYE
BYE
200 OK
200 OK
Jalava
April 21, 2023 65
SIP request routing SIP proxies route all SIP requests don't care about method (INVITE, REGISTER, DESTROY,
…) use location server based on registrations
– e.g., sip:[email protected] sip:[email protected] route to one or more destinations
– parallel forking– sequential forking
use Via header to track proxies visited loop prevention normally, only during first request in dialog
– but proxy can request visits on subsequent requests via Record-Route
– user agent copies into Route header– also used for service routing preloaded routes
April 21, 2023 66
3GGP Internet Multimedia Subsystem
services (call filtering, follow-me, …) provided in home network, via Home Subscriber Server (HSS)
may use CAMEL for providing services, but also– Call Processing Language (CPL)– SIP Common Gateway Interface (sip-cgi, RFC 3050)– SIP Servlets (JAIN)– VoiceXML for voice interaction (IVR)
use ENUM (DNS) to map E.164 numbers to SIP URIs– +46-8-9761234 becomes 4.3.2.1.6.7.9.8.6.4.e164.arpa
mechanisms and roles:– proxy servers call routing, forking– user agents (UA) voice mail, conferencing, IM– back-to-back UA (B2BUA) 3rd party call control
April 21, 2023 67
UMTS IP multimedia
April 21, 2023 68
IMS session overview
P-CSCF
I-CSCF
UA2’s visited network
UA1
UA2
UA1’s home network
S-CSCF
I-CSCF
P-CSCF
S-CSCF
I-CSCF
I-CSCF
(optional)
UA2’s home network
UA1's visited network
Jalava
April 21, 2023 69
3GPP Internet Multimedia Subsystem
UA P-CSCF I-CSCF S-CSCF
Gm Mw Mw
SLF
Dx Cx
HSS AS
Cx
SIP SIPSIP
SIPDiameter
Sh
VisitedDomain
HomeDomain
ISC
HomeSubscriber
Server
ApplicationServerSubscription
Location Function
Diameter
Call State Control Function (CSCF)
Proxy-CSCF
• Accesspoint to domain
• Hides topology and configuration
Interrogating-CSCF
• Session control services
• Registration, AS usage, charging, etc
Serving-CSCF
(User Agent)
Jalava
UE
April 21, 2023 70
Locating the P-CSCF DNS server
1. PDP Context Activation
DHCP server GGSN UE
3. DNS-Query/Response
2. DHCP-Query/Response 2. DHCP-Relay
GGSN SGSN UE
1. Activate PDP Context Request
3. Activate PDP Context Accept
1. Create PDP Context Request
3. Create PDP Context Response
2. Get IP address(es) of P-CSCF(s)
2 mechanisms:
April 21, 2023 71
3GPP SIP registration
P-CSCF HSSI-CSCF
1. Register2. Register
3. Cx-Query
UE
Visited Network Home Network
4. Cx-Query Resp
5. Cx-Select-pull
6. Cx-Select-pull Resp
10. Cx-Pull
11. Cx-Pull Resp
7. Register
13. 200 OK
14. 200 OK15. 200 OK
8. Cx-put
9. Cx-put Resp
S-CSCF
12. Service Control
TS 23.228/5.1
April 21, 2023 72
3GPP IMS call setupUE(A)
GGSN(A)
GGSN(B)
UE(B)
P-CSCF(A)
P-CSCF(A)
Other x-CSCFs
1. Session Initiation
2. Pre-alerting
3. Pre-alerting indication
4. User interaction
6. Session Progress / Session Offering
7. Initial UMTS bearer creation
8. Ringing
9. Alerting indication
10. User interaction 11. UMTS bearer modification
12. Session Acknowledgement
5. UE(B) generates accepted SDP
April 21, 2023 73
IMS call setup with QoS
1. INVITE
27. 180 Ringing
3. INVITE
UE#1 P-CSCF S-CSCF
8. 183 Session Progress
11. 183 Session Progress
12. PRACK
16. 200 OK
25. 180 Ringing
28. PRACK
31. 200 OK
35. 200 OK
37. 200 OK
19. UPDATE
22. 200 OK
38. ACK
6. INVITE
26. 180 Ringing
9.183 Session Progress
34. 200 OK
13. ResourceReservation
5. Evaluation of InitialFilter Criterias
2. 100 Trying
4. 100 Trying
7. 100 Trying
14. PRACK 15. PRACK
17. 200 OK18. 200 OK
20. UPDATE21. UPDATE
23. 200 OK24. 200 OK
29. PRACK 30. PRACK
32. 200 OK33. 200 OK
39. ACK40. ACK
Visited Network Home Network
10. Authorize QoS resources
36. Approval of QoS commit
April 21, 2023 74
SIP for mobility Terminal mobility
– same device, different attachment point• nomadic/roaming user: change between sessions• mid-session mobility
Personal mobility– same person, multiple devices– identified by SIP address-of-record
Service mobility– configuration information– address book, speed dial, caller preferences, …
Session mobility– hand-over active session to different device
• e.g., cell phone to office PC
April 21, 2023 75
SIP for terminal mobility
For most UDP applications, no need to keep constant source IP address at CH– e.g., RTP uses SSRC to identify session– others typically single request-response (DNS)
TCP: see Dutta et al. (NATs, proxies) or Snoeren/Balakrishnan TCP migration
[email protected]: 128.59.16.1
CH
registrar
re-INVITEIP2
INVITE
REGISTER IP1
REGISTER IP2
April 21, 2023 76
SIP mobility vs. mobile IP Mobility at different layers:
– permanent identifier– rendezvous point identified by that identifier– forwarding of messages
mobile IP SIP
permanent identifier
IP address SIP AOR
temporary address
care-of-address Contact header
rendezvous point home agent ( permanent address)
registrar ( host part of AOR)
HA/FA discovery ICMP not needed (name)
binding update UDP message REGISTER
in visited network foreign agent (FA) none/outbound proxy
April 21, 2023 77
SIP hierarchical registration
Contact: alice@CAFrom: alice@NY
Contact: 193.1.1.1From: alice@NY
NY
REGISTERINVITE
Los Angeles
San Francisco
Contact: 192.1.2.3From: alice@NY
CA
1
3
2
4
registrarproxy
April 21, 2023 78
SIP personal mobility
April 21, 2023 79
3GPP – IETF SIP differences
SIP terminal + authentication = 3GPP terminal
signaling as covert channel? death of SMS?
CSCFs are not quite proxies, not quite B2BUAs– modify or strip headers– initiate commands (de-registration, BYE)– edit SDP violate end-to-end encryption– modify To/From headers
April 21, 2023 80
NSIS = Next Steps in Signaling
IETF WG to explore alternatives (or profiles?) of RSVP– currently, mostly requirements and frameworks
RSVP complexity multicast support– forwarding state– killer reservations– receiver orientation not always helpful
better support for mobility– pre-reserve– tear down old reservations
layered model (Braden/Lindell, CASP)– signaling base layer, possibly on reliable transport (CASP)– applications/clients, e.g., for resources, firewall, active
networks proposals:
– trim RSVP– CASP (Cross-Application Signaling Protocol) Columbia/Siemens
April 21, 2023 81
Header compression
Wireless access networks =– high latency: 100-200ms– bit errors: 10-3, sometimes 10-2
– non-trivial residual BER– low bandwidth
IP high overhead compared with specialized circuit-switched applications:– speech frame of 15-20 octets– IPv4+UDP+RTP = 40 bytes of header, 60 with
IPv6– SIP session setup ~ 1000 bytes
April 21, 2023 82
Header compression
3GPP architecture
3GPP Architecture for all IP networks
April 21, 2023 83
Header compression
Pure use of dictionary-based compression (LZ, gzip) not sufficient
Similar to video/audio coding remove "spatial" and "temporal" redundancy
Usually, within some kind of "session" Access network (one IP hop) only Layering violation: view IP, UDP, RTP as whole see also A Unified Header Compression
Framework for Low-Bandwidth Links, Lilley/Yang/Balakrishnan/Seshan, Mobicom 2000
April 21, 2023 84
Compressed RTP (CRTP) VJ header compression for TCP uses TCP-level
retransmissions to updated decompressor RFC 2508: First attempt at RTP header
compression– 2 octets without UDP checksum, 4 with– explicit signaling messages (CONTEXT_STATE)– out-of-sync during round trip time packet loss due to
wrong/unknown headers
Improvement: TWICE– if packet loss decompressor state out of sync– use counter in CRTP to guess based on last known
packet + verify using UDP checksum– only works with UDP checksum at least 4 octets
April 21, 2023 85
Robust header compression (ROHC)
Avoid use of UDP checksums– most speech codecs tolerate bit errors– not very strong
• payload errors cause spurious header prediction failures• may accept wrong header
Loss before compression point may make compressed RTP header behavior less regular
100 ms of loss exceeds loss compensation ability ROHC: primarily for RTP streams
– header field = f(RTP seq. no)– communicate RTP seq. no reliably– if prediction incorrect, send additional information
April 21, 2023 86
ROHC
Channel assumptions:– does not reorder (but may before
compressor)– does not duplicate packets
Negotiated via PPP ROHC profiles: uncompressed,
main (RTP), UDP only, ESP onlyInitializationand Refresh
First Order Second Order
April 21, 2023 87
Header classification
inferred can be deduced from other values (e.g., length of frame)
not transmitted
static constant through lifetime of packet stream
communicate once
static-def values define packet stream
like static
static-known well-known values not transmitted
changing randomly or within range
compress by 1st/2nd order "differentiation"
April 21, 2023 88
Example: IPv6Field Size
(bits)type
Version 4 static
Traffic Class 8 changing
Flow Label 20 static-def
Payload Length 16 inferred
Next Header 8 static
Hop Limit 8 changing
Src/Dest address
2x128 static-def
inferred 2
static 1.5
static-def
34.5
changing
2
April 21, 2023 89
Example: RTP
Field Size (bits)
type
Version 2 static-known
Padding 1 static
Extension 1 static
CSRC Counter, Marker, PT
12 changing
Sequence Number 16 changing
Timestamp 32 changing
SSRC 32 static-def
CSRC 0(-480) changing
inferred 2 bits
static-def 4
static-known 2 bits
changing 7.5 (-67.5)
April 21, 2023 90
Behavior of changing fields
static additional assumptions for multimedia
semi-static occasionally changes, then reverts
rarely changing (RC)
change, then stay the same
alternating small number of values
irregular no pattern
April 21, 2023 91
Classification of changing fields
Field Value/Delta Class Knowledge
IP TOS/Traffic Class value RC unknown
IP TTL / Hop Limit value alternating limited
UDP checksum value irregular unknown
RTP CSRC, no mix value static known
RTP CSRC, mix value RC limited
RTP marker value semi-static known
RTP PT value RC unknown
RTP sequence number
delta static known
RTP timestamp delta RC limited
April 21, 2023 92
ROHC modes
Unidirectional (U)– compressor decompressor only– periodic timeouts only– starting state for all modes
Bidirectional Optimistic (O)– feedback channel for error recovery requests– optional acknowledgements of significant
context updates Bidirectional Reliable (R)
– more intensive usage of feedback channel– feedback for all context updates
April 21, 2023 93
ROHC encoding methods
Least significant bits (LSB)– header fields with small changes– k least significant bits– interpretation interval– f(vref,k) = [vref – p, vref + (2k –1) – p]– p picked depending on bias of header
field window-based LSB (W-LSB)
– compressor maintains candidates for decompressor reference value
April 21, 2023 94
ROHC encoding methods, cont'd
Scaled RTP timestamp encoding– RTP increases by multiple of TS_STRIDE– e.g., 20 ms frames TS_STRIDE=160– downscale by TS_STRIDE, then W-LSB
Timer-based compression of RTP timestamp– local clock can provide estimate of TS– if jitter is bounded– works well after talkspurts
Offset IP-ID encoding– compress (IP-ID – RTP SN)
Self-describing variable length encoding– prefix coding: 0 + 1o, 10 + 2o, 110 + 3o, 1110 + 4o
April 21, 2023 95
ROHC
duplicate,reorder, losepackets
ACKNACK
compressorde-
compressor
• typically, multiple streams for each channel• identified by channel identifier (CID)• protected by 3-8 bit CRC
April 21, 2023 96
ROHC CRC Qiao: add one-bit correction CRC helps with BER of 4-5%
Full header
CRC
Compressed header
CRC
Decompressed header
CRC
Validate
Qiao
April 21, 2023 97
Signaling compression (SigComp)
Textual signaling protocols like SIP, RTSP and maybe HTTP– long signaling messages ( kB)– signaling delays call setup delays (56 ms/1 kB @ 144
kb/s)
– less of an issue: total overhead– long packets header overhead not a major issue
unlike ROHC, assume reliable transport
SIPproxy
SigComp
ROHC
April 21, 2023 98
Signaling compression
compressor1
compressor2
statehandler
state 1
state 2
de-compressor(UDVM)
compressordispatcher
decompressordispatcher
transport layer (TCP, UDP, SCTP)
SigCompmessage SigComp
message
application message& compartment id
decompressedmessage
SigComplayer
compartmentidentifier
April 21, 2023 99
SigComp
Messages marked with special invalid UTF-8 bit sequence (11111xxx)
State saved across messages in compartment– memory size is limited (> 2 KB)– CPU expenditure is limited, measured in cycles
per bit
Universal Decompressor Virtual Machine (UDVM):– compressor can choose any algorithm to
compress– upload byte code as state
April 21, 2023 100
SigComp UDVM bytecode
virtual machine with registers and stack single byte opcode + literal, reference,
multitype and address
UDVM
decompressordispatcher
request compressed data
provide compressed dataoutput decompressed data
indicate end of message
provide compartment identifier
statehandler
request state information
provide state information
make state creation request
forward feedback information
April 21, 2023 101
SigComp virtual machine
arithmetic: and, or, not, left/right shift, integer add/subtract/multiply/divide, remainder on 16-bit words
sort 16-bit words ascending/descending SHA-1, CRC load, multiload, copy, memset, push, pop jump, call, return, switch input, output state create and free
April 21, 2023 102
Example: SIP compression
SIP compression most likely will use a static dictionary– e.g., "sip:", "INVITE ", "[CRLF]Via: SIP/2.0/UDP "
referenced as state works best with default-formatted messages
(e.g., single space between : and header field) permanently defined used with a variety of algorithms, such as
DEFLATE, LZ78, … Capability indicated using NAPTR records and
REGISTER parameter;; order pref flags service regexp replacement IN NAPTR 100 100 "s" "SIP+D2T" "" _sip._tcp.school.eduIN NAPTR 100 100 "s" "SIP+D2U" "" _sip._udp.example.com
IN NAPTR 100 100 "s" "SIP+D2CU" "" comp-udp.example.com
April 21, 2023 103
RTP unequal error protection Provide generic protection of RTP headers
and payload against packet loss– may also handle uncorrected bit errors
RFC 2733: XOR across packets FEC packet
ULP (uneven level protection): higher protection for bits at beginning of packet– higher protection = smaller group sizes– common for most codecs: closer to sync marker– H.263: video macroblock header, motion vectors– modern audio codecs– stretching of existing audio codecs
April 21, 2023 104
RTP unequal error protection
separate FEC packets or piggy-backed multiple FEC in one packet ULP header adds protection length and
mask recovery bytes are XOR(packet headers) negotiated via SDP
RTP seq. number base
RTP timestamp recovery
bit mask (packets after SN base)
length recovery
PT recoveryE
April 21, 2023 105
Unequal erasure protection (UXP)
Alternative to ULP, with different properties uses interleaving + Reed-Solomon codes
(GF(28)) to recover from packet loss (erasure)
allows unequal protection of different parts of payload
allows arbitrary packet size optimize for channel
interleaving adds delay ULP only incurs delay after packet loss (but
this may introduce gaps)
April 21, 2023 106
UDPLite
Proposal by Larzon&Degermark partial checksum coverage
– at least UDP header bytes
source port destination port
checksum coverage UDP checksum
data bytes
April 21, 2023 107
Fast handoff – hand-off latency
Allow only a few lost packets < 100 ms hand-off delay
detect new network from AP MAC address– maybe use other packets listened to?– scan different frequencies
• may need to scan both 2.4 and 5 GHz regions (802.11a, b, g)
– passive scanning: wait for AP beacon• 802.11 beacon interval = 100 kµs ~ 100 ms
– active scanning: Probe Request Frame + Probe Response
associate with new network– 802.11i authentication– IETF PANA WG – L2-independent access control
April 21, 2023 108
Handoff latency
duplicate address detection (DAD) – DHCP
• DHCPDISCOVER, DHCPOFFER, DHCPREQUEST, DHCPACK multiple RTT, plus possible retransmissions
– IPv6 stateless autoconfiguration (RFC 2461, 2462)• delay first Neighbor Solicitation in
[0,MAX_RTR_SOLICITATION_DELAY], where MAX_RTR_SOLICITATION_DELAY = 1s
• wait for RetransTimer (1s) for answer
AAA (authentication, authorization, accounting)– usually, RADIUS or (future) DIAMETER– server may be far away
April 21, 2023 109
MIPv6 delays
Site1
Internet
CH
HA2
3
CoA
Site1
Internet
1
2BU=HA, CoA
BU=HA, CoA
1
Castelluccia/Bellier
April 21, 2023 110
Micro-mobility Separate local (intra-domain, frequent)
movement from inter-domain movement (rare) 3 mobility protocol layers: L2 (e.g., 802.11, 3G
RAN), micro, macro– also offer paging (usefulness with chatty UEs?)– assumption may not be correct
Examples:– hierarchical foreign agents (Nokia, 1996)– Cellular IP (Columbia/Ericsson, 1998)– Hierarchical IPv6 (INRIA, 1998)– HAWAII (Lucent, 1999)– THEMA (Lucent/Nokia, 1999)– TeleMIP (Telcordia, IBM, 2001)
ISP1
ISP2
100'
April 21, 2023 111
Micro-mobility design goals Scalability
– process updates locally Limit disruption
– forward packets if necessary Efficiency
– avoid tunneling where possible Quality of Service (QoS) support
– local restoration of reservations Reliability
– leverage fault detection mechanisms in routing protocols
Transparency– minimal impact at the mobile host
Ramjee
April 21, 2023 112
Micro-mobility Methods based on re-addressing
– "keep routes, change address"– typically, tunnels within domain– hierarchical FAs– MIP with CoA to world at large– e.g.,
• regional registration, region-aware foreign agents, Dynamics, hierarchical MIPv6, …
Routing-based– "keep address, change routes"– no tunnels within domain– host-based (mobile-specific) routes– e.g.,
• Cellular IP, HAWAII
Hartenstein et al.
April 21, 2023 113
Cellular IP
April 21, 2023 114
Cellular IP base station routes
IP routes cellular IP routing
gateway support MIP macro mobility– provides CoA
inside micro mobility domain, packets identified by H@– no tunneling, no
address conversion
MH data packets establish location and routing "soft state"
no explicit signaling– empty IP packets– discarded at border
symmetric paths uplink establishes
shortest path to MH per-host routes, hop-
by-hopGomez/Campbell
April 21, 2023 115
Cellular IP: Hard handoff
Internet w/ Mobile IP
foreign agent
home agent
C
A
B
E
D
F
G
R
RR
host
Gomez/Campbell
April 21, 2023 116
Cellular IP: downlink HO loss
April 21, 2023 117
Distributed control: Reliability and scalability– host-based routing entries in routers on path to mobile
Localized mobility management: Fast handoffs– updates only reach routers affected by movement
Minimized or Eliminated Tunneling: Efficient routing– dynamic, public address assignment to mobile devices
DomainRouter
RR
R R R R
DomainRouter
RR
R R R R
Local mobility Local mobilityMobile IP
Internet
MD
HAWAII: Enhanced Mobile IP
Ramjee
April 21, 2023 118
HAWAII
Mobile IP
Internet
1.1.1.100->port 4, 239.0.0.1
1.1.1.100-> port 3, 239.0.0.1
1.1.1.100->wireless, 239.0.0.1
R
23
1
R1
23 4
5
MY IP: 1.1.1.100BS IP:1.1.1.5
1
R2 3
4 R1
23 4
5
R 2 3
14 4
DomainRootRouter 2
DomainRootRouter 1
5
BS1
2
34
5
BS2 BS3 BS4
1
Power-up
Ramjee
April 21, 2023 119
Host-based routing entries maintained as soft-state
Base-stations and mobile hosts periodically refresh the soft-state
HAWAII leverages routing protocol failure detection and recovery mechanisms to recover from failures
Recovery from link/router failures
Soft-State
Ramjee
April 21, 2023 120
HAWAII
Mobile IP
Failure Recovery
Internet
1.1.1.100->port 3, 239.0.0.1
1.1.1.100-> port 4, 239.0.0.1
1.1.1.100->wireless, 239.0.0.1
R
23
1
R1
23 4
5
MY IP: 1.1.1.100BS IP:1.1.1.5
1
R2 3
4 R1
23 4
5
R 2 3
14 4
DomainRootRouter 2
DomainRootRouter 1
5
BS1
2
3
BS2 BS3 BS4
1
Ramjee
April 21, 2023 121
Host-based routing within the domain
Path setup schemes selectively update local routers as users move
Path setup schemes customized based on user, application, or wireless network characteristics
Micro-mobility handled locally with limited disruption to user traffic
Path Setup Schemes
Ramjee
April 21, 2023 122
HAWAII
Mobile IP
Internet
1.1.1.100->port 3 (4), 239.0.0.1
1.1.1.100-> port 3, 239.0.0.1
R
23
1
R1
23 4
5
MY IP: 1.1.1.100BS IP:1.1.1.2
R2 3
4 R1
23 4
5
R 2 3
14 4
DomainRootRouter 2
DomainRootRouter 1
5
BS1
2 34
1.1.1.100->wireless, 239.0.0.1 1 5
BS2 BS3 BS4
1.1.1.100->port 1(wireless), 239.0.0.1
1
Micro-Mobility
Ramjee
April 21, 2023 123
MY IP: 1.1.1.100BS IP:1.1.2.1COA IP:1.1.2.200
Internet
1.1.2.200->port 2, 239.0.0.1
1.1.2.200-> port 3, 239.0.0.1
1.1.2.200->wireless, 239.0.0.2
HAWAII
Mobile IP
R
23
1
R1
23 4
5
1
R2 3
4 R1
23 4
5
R 2 3
14 4
DomainRootRouter 2
DomainRootRouter 1
5
BS1
2
34
5
BS2 BS3 BS4
1
Mobile IP Home Agent:1.1.1.100-> 1.1.2.200
6
7
Macro-Mobility
Ramjee
April 21, 2023 124
Simulation Topology
Ramjee
April 21, 2023 125
Performance: Audio and Video
Ramjee
April 21, 2023 126
TORA O'Neill/Corson/Tsirtsis "make before break" hierarchical
CR CR CR
IR
ER
MH
ER
IR IR
ER
MH
(0,0,0,3,i)
(0,0,0,4,i)
(0,0,0,5,i)
CR
IR
ER
(0,0,0,4,i)(0,0,0,4,i) (0,0,0,5,i)
(-2,0,0,5,i)
(-2,0,0,4,i)
(-2,0,0,3,i)
(-2,0,0,2,i)
(-2,0,0,1,i)
(-2,0,0,0,i)
(0,0,0,5,i)
(0,0,0,6,i)
(0,0,0,6,i)
(0,0,0,7,i)
(0,0,0,8,i)(-1,0,0,5,i)
(-1,0,0,3,i)
(-2,0,0,6,i)
(-2,0,0,7,i)(0,0,0,1,i)
(0,0,0,2,i)
(0,0,0,3,i)
(0,0,0,4,i)
(0,0,0,5,i) ARAR AR AR
(-1,0,0,4,i)
core
interior
edge
access
April 21, 2023 127
Hierarchical Mobility Agents
Home Agent
GMA
LMA
Localize signaling to visited domain Regional Registration/Regional Binding Update uses IP tunnels (encapsulation) only, only one level of hierarchy
RMA
Perkins
April 21, 2023 128
Example: hierarchical FA(Dynamics, HUT)
HACN
HFA
FA2
FA3
FA13
FA29 FA14
FA32
FA15
FA1
Location update latencies for some transitions
FA11 FA12
FA13
FA31
OLD FA
NEW FA
Average in ms
FA11 FA12 19,1FA13 FA14 30,4FA31 FA32 41,4
Forsberg et al
April 21, 2023 129
Hierarchical FA with soft hand-off
HACN
HFA
FA12
FA3
FA31
FA29 FA14
FA32
FA15
FA11
FA3FA3FA13 Data stream CN --> MN
OLD FA
NEW FA
Lost packets/ update
FA11 FA31 0.00FA31 FA29 0.00FA29 FA32 0.00FA31 FA13 0.00FA12 FA15 0.00FA15 FA31 0.03FA32 FA11 0.07FA13 FA12 0.10
OLD FA
NEW FA
Lost packets/ update
FA11 FA31 0.27FA31 FA29 0.27FA29 FA32 0.00FA31 FA13 0.15FA12 FA15 0.14FA15 FA31 0.00FA32 FA11 0.00FA13 FA12 0.00
Data stream MN --> CN
Data stream: 100kB/s, 1kB
packets (100 packets/s)
HUT Dynamics802.11
April 21, 2023 130
INRIA HMIPv6 inter-site (global,
macro) vs. intra-site (local, micro)
CH only aware of inter-site mobility
MIPv6 used to manage macro and micro mobility
define MN as LAN connected to border router, with >= 1 MS
use site-local IPv6 addresses?
Site1
Internet
MN
MSBR
Castelluccia/Bellier
April 21, 2023 131
INRIA HMIPv6 MH gets 2 CoA:
– VCoA in the MN stays constant within site
– PCoA (private CoA) changes with each micromove
MH registers– (H@,VCoA) external
CH– (H@,PCoA) local CHs– (VCoA, PCoA) MS
MH obtains MS address and MN prefix via router advertisements
Internet
PCoA
VCoA
(VCoA,PCoA)
(H@,PCoA)
(H@,VCoA)
April 21, 2023 132
INRIA HMIPv6 – packet delivery
External CH sends to VCoA– MS in MN
intercepts and routes to MH
Local CH sends to PCoA
MS
Site1
Internet
MN
April 21, 2023 133
INRIA HMIPv6 – micro mobility registration
MH moves and gets new PCoA (PCoA1)
sends BU (VCoA, PCoA1) to its MS
sends BU (H@, PCoA1) to local CHs
MS
Internet
(VCoA,PCoA)
(HA,PCoA)
(H@,PCoA1)
PCoA1
April 21, 2023 134
Other approaches to latency reduction
IP-based soft handoff buffering of in-flight data in old FA
– forward to new CoA or new BS multicast to multiple base stations
– unicast multicast unicast– often, down some hierarchy– multicast address assignment?
UMTS / 802.11 "vertical" hand-off– UMTS as "background radiation"
Domain1 Domain2
MA
1 23
4
Hartenstein et al.
April 21, 2023 135
Comparison of CIP, HAWAII, HMIP
Cellular IP HAWAII HMIP
OSI layer L3 L3 "L3.5"
Nodes all CIP nodes all routers FAs
Mobile host ID home address
care-of-address
home address
Intermediate nodes L2 switches L2 switches L3 routers
Means of update data packet signaling msg. signaling msg.
Paging implicit explicit explicit
Tunneling no no yes
L2 triggered hand-off
optional optional no
MIP messaging no yes yes
Campbell/Gomez-Castellanos
April 21, 2023 136
Network-assisted hand-off Network makes hand-off decision, rather than
UE network sets up resources (QoS) to new FA/BS simultaneous bindings kept and destroyed by
network allows seamless handoff IP nodes may need to report PHY measurements
(like GSM) e.g., Hartenstein et al., Calhoun/Kempf (FA-
assisted hand-off) may need to be able to predict next access
point
April 21, 2023 137
Cost of networking
Modality mode
speed $/MB (= 1 minute of 64 kb/s videoconferencing or 1/3 MP3)
OC-3 P 155 Mb/s $0.0013
Australian DSL(512/128 kb/s)
P 512/128 kb/s
$0.018
GSM voice C 8 kb/s $0.66-$1.70
HSCSD C 20 kb/s $2.06
GPRS P 25 kb/s $4-$10
Iridium C 10 kb/s $20
SMS (160 chars/message) P ? $62.50
Motient (BlackBerry) P 8 kb/s $133
April 21, 2023 138
Spectrum cost for 3G
Location what costUK 3G $590/person
Germany 3G $558/person
Italy 3G $200/person
New York Verizon(20MHz)
$220/customer
Generally, license limited to 10-15 years
April 21, 2023 139
Multimodal networking = use multiple types of networks, with
transparent movement of information technical integration (IP) access/business
integration (roaming) variables: ubiquity, access speed, cost/bit,
… 2G/3G: rely on value of ubiquity immediacy
– but: demise of Iridium and other satellite efforts similar to early wired Internet or some
international locations– e.g., Australia
April 21, 2023 140
Multimodal networking
expand reach by leveraging mobility locality of data references
– mobile Internet not for general research– Zipf distribution for multimedia content
• short movies, MP3s, news, …
– newspapers– local information (maps, schedules, traffic
radio, weather, tourist information)
April 21, 2023 141
Multimedia data access modalities
high low
high 7DS 802.11hotspots
low satelliteSMS?
voice (2G, 2.5G)
band
wid
th(p
eak)
delay
April 21, 2023 142
A family of access points
Infostation
2G/3G
access sharing
7DS
hotspot + cache
WLAN
April 21, 2023 143
7DS options
Many degrees of cooperation server to client
– only server shares data– no cooperation among clients– fixed and mobile information servers
peer-to-peer– data sharing and query forwarding
among peers
April 21, 2023 144
7DS options
Query Forwarding
Host A Host B
query
FWquery
Host C
time
Querying
active (periodic)
passive
Power conservation
on
off time
communication enabled
April 21, 2023 145
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25
Density of hosts (#hosts/km )
Da
tah
old
ers
(%
) P2P data sharing(power cons.)
P2P data sharing
P2P data sharing & FW(power cons.)
Fixed Info Server
Mobile Info Server
Dataholders (%) after 25 minhigh transmission power
2
Fixed Info Server
Mobile Info Server
P2P
April 21, 2023 146
Message relaying with 7DS
Host B
Messagerelaying
Host A
messages
Gateway
WAN
Host AWLAN
WLAN
April 21, 2023 147
Conclusion and outlook
First packet-based wireless multimedia networks going into production
encumbered by legacy technology and business model ("minutes")
what is 4G? store-and-forward beats interactive
– SMS, email vs. phone calls
cost and complexity remain the major challenges– interworking across generations, from 1876
role of multimedia in ad-hoc networks?– ad hoc access (small hop count) + backbone
April 21, 2023 148
Credits Figures and results
(with permission) from– Emmanuel Coelho
Alves– Andrew Campbell– Ashutosh Dutta– Mustafa Ergen– Javier Gomez– Wolfgang Granzow– Teemu Jalava– Wenyu Jiang– Andreas Koepsel– Maria Papadopouli– Charles Perkins– Zizhi Qiao
– Ramachandran Ramjee
– Henning Sanneck– Adam Wolisz– Moshe Zukerman– Kanter, Maguire,
Escudero-Pascual– and others
April 21, 2023 149
UMTS IP multimedia