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Wireless IP Multimedia Henning Schulzrinne Columbia University MOBICOM Tutorial, September 2002 7 May 2017 Overview Types of wireless multimedia applications – streaming – interactive – object delivery Properties of multimedia content – loss resiliency – delay – reordering 3G and WLAN MMrelated channel properties – effective bandwidth – packet loss – delay 7 May 2017 Header and signaling compression – cRTP – ROHC – signaling compression Packet FEC UMTS multimedia subsystem (IMS) – QoS – Session setup Fast handoff mechanisms Multimodal networking Types of wireless multimedia applications Streaming – video/audio on demand – may be cached at various places, including end system Interactive – VoIP – multimedia conferences – multiplayer games Object retrieval – peer-to-peer – user may be waiting for result Messaging – store-and-forward (e.g., MMS) – can be batched 7 May 2017 IETF (multimedia) protocols SAP SDP MGCP DHCPP SIP RTSP RSVP Network TCP Physical PPP SONET 7 May 2017 RTCP RTP DNS LDAP CIP MIP (H.261. MPEG) UDP IDMP MIP-LR MIPv6 IPv4, IPv6, IP Multicast ICMP AAL3/4 ATM AAL5 IGMP PPP 802.11b Heterogeneous Access Ethernet CDMA 1XRTT /GPRS Kernel H.323 media encap Application Media Transport Signaling Common wired & wireless audio codecs codec name standards org. sampling rate 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 ETSI (adaptive multi-rate) 26.090 (1999) 8,000 20 ms 4.75 – 12.2 (8) 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 7 May 2017 frame size bit rate (kb/s) (Hz) 6.7: PDC-EFR 7.4: IS 641 12.2: GSM-EFR 16,000 20 ms 6.6 – 23.85 (9) Audio codecs, cont'd. codec name standards org. samplin g rate EVRC (RCELP) TIA/EIA (1996) G.726 (ADPCM) G.728 (LD-CELP) 7 May 2017 frame size bit rate (kb/s) 8,000 20 ms 8.55, 4, 0.8 ITU 8,000 sample 16, 24, 32, 40 ITU 8,000 20 ms 16 (Hz) 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 nonzero 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 7 May 2017 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 original 4 6 8 10 12 14 16 18 20 G.723.1 G.729 G.729A AMR-NB AMR-WB 7 May 2017 www.voiceage.com 22 24 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) 7 May 2017 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 7 May 2017 Video codecs JPEG e.g., DCT: spatial frequency Frames of Digital Video Motion Estimation & Compensation predict current frame from previous common code words shorter symbols Huffman, arithmetic coding Transform, Quantization, ZigZag Scan & RunLength Encoding Symbol Encoder Bit Stream Quantization changes representation size for each symbol adjust rate/quality trade-off Run-length encoding: long runs of zeros run-length symbol 7 May 2017 MPEG, H.26x courtesy M. Khansari History of video codecs H.261 ITU-T H.263 H.263++ H.263+ ISO MPEG 1 MPEG 4 MPEG 2 1990 7 May 2017 1992 H.263L 1994 1996 MPEG 7 1998 2000 2002 courtesy M. Khansari H.263L example 64 kb/s, 15 fps 7 May 2017 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]: • • • • 7 May 2017 web browser response VCR control for streaming media ringback delay for call setup can often be bridged by application design 802.11 architecture ESS Existing Wired LAN AP STA BSS AP STA STA BSS STA Infrastructure Network STA Ad Hoc Network STA BSS BSS STA Ad Hoc Network STA Mustafa Ergen 7 May 2017 802.11b hand-off Kanter, Maguire, Escudero-Pascual, 2001 7 May 2017 802.11 delay channel is busy idle slots Data ACK idle slots time DIFS SIFS (DCF interframe space) idle slots DIFS (short IFS) RTS CTS Data idle slots ACK time DIFS SIFS IFS (µs) 7 May 2017 SIFS SIFS FHSS DSSS DIFS OFDM SIFS 28 10 13 PIFS 78 30 19 DIFS 128 50 25 M. Zukerman 802.11 delay 802.11 1, 2 Mb/s DSSS 802.11b 11 Mb/s FHSS, DSSS 802.11a 2, 11, 24, 54 Mb/s OFDM 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 7 May 2017 Mean data frame delay (msec) 802.11 delay Payload: 512 bits 2430 bits 4348 bits 8184 bits 7 May 2017 Throughput 802.11 delay Mean message delay (msec) Hyper-geometric Geometric Dual fixed Fixed 7 May 2017 Throughput 802.11a delay for VoIP 7 May 2017 802.11b channel access delay Köpsel/Wolisz • 12 mobile data nodes, 4 mobile with on/off audio • 6 Mb/s load 7 May 2017 802.11b VoIP delay Köpsel/Wolisz WoWMoM 2001: add priority and PCF enhancement to improve voice delay DCF Köpsel/Wolisz 7 May 2017 802.11b – PCF+priority poll only stations with audio data move audio flows from PCF to DCF and back after talkspurts Köpsel/Wolisz • IEEE 802.11 TGe working on enhancements for MAC (PCF and DCF) • multiple priority queues 7 May 2017 802.11e = enhanced DCF HC hybrid controller TC traffic categories AIFS arbitration IFS TXOP transmission opportunity Mustafa Ergen 7 May 2017 802.11e back-off 7 May 2017 Metric of VoIP quality Mean Opinion Score (MOS) [ITU P.830] – Obtained via human-based listening tests – Listening (MOS) vs. conversational (MOSc) 4 Quality 5 Excellent 4 Good 3 Fair 2 Poor 1 Bad 7 May 2017 3.5 MOS Grade iLBC 14kb/s G.729 8kb/s G.723.1 6.3kb/s 3 2.5 2 1.5 0 0.03 0.06 0.09 0.12 0.15 average loss probability FEC and IP header overhead An (n,k) FEC code has (n-k)/k overhead Typical IP/UDP/RTP header is 40 bytes codec iLBC (4,2) FEC media pkt size (T=30ms) rmedia rIP 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 7 May 2017 Predicting MOS in VoIP The E-model: an alternative to humanbased 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 7 May 2017 Predicting MOS in VoIP, contd – From loss and delay to their impairment scores and to MOS 35 E-model Id 45 Ie (loss impairment) Example mappings 50 40 35 30 25 20 15 10 0 25 3.5 Id (delay impairment) 4 MOS 3 2 10 1.5 5 1 7 May 20170 R to MOS mapping 2.5 15 0 0.18 4.5 30 20 G.729 T=20ms random loss 0.03 0.06 0.09 0.12 0.15 average loss probability 50 100 150 200 250 300 350 400 delay (ms) 0.5 20 40 60 R value 80 100 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 7 May 2017 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 7 May 2017 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) 4 3.8 3.8 3.6 3.6 3.4 3.4 MOS MOS_c 4 3.2 3.2 3 2.8 G.729+(5,3) 2.6 G.729+(5,3),T=60ms iLBC,no FEC 2.4 0 0.03 0.06 0.09 0.12 average loss probability 7 May 2017 G.729+(5,3) G.729+(5,3),T=60ms iLBC, no FEC 3 2.8 2.6 0.15 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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 4 3.8 3.8 3.6 3.6 3.4 3.4 MOS MOS_c 4 3.2 3.2 3 2.8 2.4 2.8 G.729+(5,2) G.729+(5,2),T=60ms iLBC+(3,2) 2.6 0 7 May 2017 0.03 0.06 0.09 0.12 average loss probability 3 G.729+(5,2) G.729+(5,2),T=60ms iLBC+(3,2) FEC 2.6 0.15 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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 4 3.8 3.8 3.6 3.6 3.4 3.4 MOS MOS_c 4 3.2 3.2 3 2.8 2.4 2.8 G.729+(7,2) iLBC+(4,2) 2.6 0 7 May 2017 0.03 0.06 0.09 0.12 average loss probability 3 G.729+(7,2) iLBC+(4,2) 2.6 0.15 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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 4 3.8 3.8 3.6 3.6 3.4 3.4 MOS MOS_c 4 3.2 3.2 3 2.8 2.4 2.8 G.729+(3,1) iLBC+(4,2) 2.6 0 0.03 0.06 0.09 0.12 average loss probability 7 May 2017 3 G.729+(3,1) iLBC+(4,2) 2.6 0.15 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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 4 4 G.723.1+(2,1) G.723.1+(2,1),T=60ms iLBC, no FEC 3.8 3.6 3.8 3.6 3.4 MOS MOS_c 3.4 3.2 3.2 3 2.8 2.8 2.6 2.4 3 0 0.03 0.06 0.09 0.12 average loss probability 7 May 2017 0.15 G.723.1+(2,1) 2.6 G.723.1+(2,1),T=60ms iLBC,no FEC 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 G.723.1+(3,1) vs. iLBC+(3,2) iLBC is still better for low loss G.723.1 wins for higher loss 4 3.8 3.8 3.6 3.6 3.4 3.4 MOS MOS_c 4 3.2 3.2 3 2.8 G.723.1+(3,1) G.723.1+(3,1),T=60ms 2.6 iLBC+(3,2) 2.4 0 0.03 0.06 0.09 0.12 average loss probability 7 May 2017 3 2.8 0.15 G.723.1+(3,1) G.723.1+(3,1),T=60ms 2.6 iLBC+(3,2) 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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” 4 3.8 3.8 3.6 3.6 3.4 3.4 MOS MOS_c 4 3.2 3.2 3 2.8 G.723.1+(4,1) G.723.1+(4,1),T=60ms 2.6 iLBC+(4,2) 2.4 0 0.03 0.06 0.09 0.12 average loss probability 7 May 2017 3 2.8 0.15 G.723.1+(4,1) G.723.1+(4,1),T=60ms 2.6 iLBC+(4,2) 2.4 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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) 4 iLBC,no FEC G.729+(5,3) G.723.1+(2,1),T=60ms 3.8 3.6 MOS_c MOS_c 3.4 3.2 3 2.8 2.6 2.4 0 7 May 2017 0.03 0.06 0.09 0.12 average loss probability 0.15 4 iLBC Max BW: 14 kb/s 3.8 G.723.1+(2,1),T=60ms 3.6 3.4 3.2 G.729+(5,3) 3 2.8 2.6 2.4 0 0.03 0.06 0.09 0.12 0.15 average loss probability Max Bandwidth: 21-28 kb/s 4 iLBC, no FEC G.729+(5,2) 3.8 3.6 MOS_c MOS_c 3.4 3.2 3 2.8 2.6 2.4 0 4 0.03 0.06 0.09 0.12 average loss probability 0.15 iLBC, no FEC G.729+(3,1) G.729+(5,2) 3.8 3.6 MOS_c MOS_c 3.4 3.2 3 2.8 2.6 2.4 0 7 May 2017 0.03 0.06 0.09 0.12 average loss probability 0.15 4 iLBC Max BW: 21 kb/s 3.8 3.6 3.4 G.729+(5,2) 3.2 3 2.8 2.6 2.4 0 0.03 0.06 0.09 0.12 0.15 average loss probability 4 iLBC Max BW: 28 kb/s 3.8 3.6 3.4 G.729+(3,1) G.729+(5,2) 3.2 3 2.8 2.6 2.4 0 0.03 0.06 0.09 0.12 0.15 average loss probability 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 4 3.8 3.6 MOS_c 3.4 3.2 3 2.8 Max BW: 14 kb/s Max BW: 21 kb/s Max BW: 28 kb/s 2.6 2.4 7 May 2017 0 0.03 0.06 0.09 0.12 average loss probability 0.15 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 7 May 2017 UMTS macrocell 2 km 144 kb/s microcell 1 km 384 kb/s picocell 60 m 2 Mb/s 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 7 May 2017 1G-3G air interface 1G 2G “2.5G” 3G/ IMT-2000 Capable Existing Spectrum Analog AMPS IS-95-A/ cdmaOne IS-95-B/ cdmaOne New Spectrum cdma2000 1X (1.25 MHz) cdma2000 3X (5 MHz) 1XEV DO: HDR (1.25 MHz) 136 HS EDGE IS-136 TDMA TACS GSM GPRS EDGE GSM WCDMA HSCSD 7 May 2017 Ramjee 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 7 May 2017 UMTS UTRAN Packet switched Core Network IP server UE Application Applic. GGSN TCP Radio Access Bearers IP IP TCP IP IP SGSN RNC Radio Bearers PDCP RLC Logical channels MAC Transport channels PHY PDCP Iu UP Iu UP RLC GTP-U GTP-U MAC UDP UDP Node B PHY FP FP PHY AAL2/ ATM AAL2/ ATM IP IP AAL5/ ATM AAL5/ ATM GTP-U GTP-U GPRS IP backbone UDP/ TCP IP routing IP IP IP UDP/ TCP IP Physical channels Uu Iub Iu Gn Gn/Gp Gi W. Granzow 7 May 2017 3GPP network architecture Iu Uu End user terminal Radio Access Network Core Network AS 7 May 2017 Jalava 3GPP network architecture gateways Legacy Mobile Signaling Networks Multimedia IP Networks Roaming Signaling Gateway (R-SGW) Mh Mm Ms HSS CSCF Gi Cx Mg Mr Gi MRF Gi SGSN GGSN Media Gateway Control Function (MGCF) Transport Switching Gateway (T-SGW) Mc (= H.248) Media Gateway (MGW) 7 May 2017 Gi Media Gateway (MGW) PSTN/Legacy/External Alves 3GPP networks – call control -View on CALL CONTROL Applications & Services VHE / OSA CAP Application I/F Home Subscriber Server (HSS) Call State Control Function (CSCF) Cx Mr (=HLR + +) Gr Gc Gi Multimedia Resource Function (MRF) Gi access SGSN Gn to other networks GGSN Iu Gf EIR 7 May 2017 Alves UMTS network architecture MSC GSN RNC Node B Mobile Services Switching Center GPRS Support Node MSC/GSN Radio Network controller Base Node RNC RNC Radio network System (RNS) Node B Node B Node B Node B Node B 7 May 2017 No Node B W. Granzow 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. 7 May 2017 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 reassignment scheduling • Downlink Shared Channel (DSCH) 7 May 2017 Transmission Format UTRA FDD 1 radio frame (10 ms), 15*2560 chips (3.84 Mcps) Slot 1 Slot 2 Slot i Uplink frequency Microcell layer 5 MHz 5 MHz Duplex distance, e.g. 190 MHz 7 May 2017 time Downlink Macrocell layers 5 MHz Slot 15 5 MHz UMTS/3G QoS classes conversational voice, video conferencing streaming video streaming interactive low delay, strict ordering modest delay, strict ordering web browsing, games modest delay background email download 7 May 2017 no delay guarantees QoS class requirements Excerpt from 3GPP TS 23.107: Traffic class Conversational Streaming 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- 10-3, 10-4, 10-6 Transfer delay 100 ms 250 ms Guaranteed bit rate 2,048 kb/s 2,048 kb/s Traffic handling priority Allocation/retention priority 7 May 2017 Interactive 6 Background 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 GPRS delay Gurtov, PWC 2001 7 May 2017 UMTS transport External PLMN Gp Iub RBS UE UTRAN RNC Host GGSN Gn IP Network UMTS/GPRS Backbone (IPv4) SGSN Appl Appl TCP/UDP TCP/UDP IP IP Relay GTP-U GTP-U Relay PDCP GTP-U PDCP RLC MAC MAC IP IP IP IP L1 L1 L2/L1 L2/L1 L2/L1 L2/L1 UE Uu UTRAN User level IP Transport level IP 7 May 2017 UDP Iu-PS UDP SGSN IP L2 L2 L1 L1 GTP-U RLC UDP IP UDP Gn/Gp GGSN Gi Host UMTS Release 4/5 Architecture Kulkarni 7 May 2017 UMTS IP multimedia 7 May 2017 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 7 May 2017 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 7 May 2017 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 7 May 2017 Session setup: SIP INVITE INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP pc33.atlanta.com [email protected]: ;branch=z9 128.59.16.1 Max-Forwards: 70 To: Bob <sip:[email protected]> REGISTER From: Alice <sip:[email protected]> ;tag=1928301774 Call-ID: [email protected] CSeq: 314159 INVITE Contact: <sip:[email protected]> Content-Type: application/sdp Content-Length: 142 BYE 7 May 2017 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 Client 1 Client 2 INVITE 100 Trying INVITE 180 Ringing 180 Ringing 200 OK 200 OK ACK ACK Media streams BYE BYE 200 OK 200 OK – sip:[email protected] – tel:+1-212-555-1234 Jalava 7 May 2017 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 RecordRoute – user agent copies into Route header – also used for service routing preloaded routes 7 May 2017 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 7 May 2017 3GPP Internet Multimedia Subsystem Call State Control Function (CSCF) Interrogating-CSCF • Accesspoint to domain Subscription Location Function HSS Diameter Diameter Cx Dx UE Gm UA Mw P-CSCF (User Agent) SIP AS ISC Cx SIP Mw I-CSCF SIP Visited Domain Application Server Sh SLF • Hides topology and configuration Proxy-CSCF Home Subscriber Server S-CSCF SIP Home Domain Serving-CSCF • Session control services • Registration, AS usage, charging, etc 7 May 2017 Jalava IMS session overview UA1 UA1's visited network UA1’s home network P-CSCF S-CSCF I-CSCF (optional) I-CSCF UA2 I-CSCF S-CSCF I-CSCF P-CSCF UA2’s home network UA2’s visited network 7 May 2017 Jalava Locating the P-CSCF UE GGSN DHCP server DNS server 1. PDP Context Activation 2. DHCP-Query/Response 2. DHCP-Relay 3. DNS-Query/Response 2 mechanisms: UE SGSN GGSN 1. Activate PDP Context Request 1. Create PDP Context Request 2. Get IP address(es) of P-CSCF(s) 3. Create PDP Context Response 3. Activate PDP Context Accept 7 May 2017 3GPP SIP registration Visited Network UE Home Network P-CSCF I-CSCF HSS S-CSCF 1. Register 2. Register 3. Cx-Query 4. Cx-Query Resp 5. Cx-Select-pull 6. Cx-Select-pull Resp 7. Register 8. Cx-put 9. Cx-put Resp 10. Cx-Pull 11. Cx-Pull Resp 12. Service Control 13. 200 OK 15. 200 OK 14. 200 OK sip:[email protected] 7 May 2017 TS 23.228/5.1 3GPP IMS call setup UE(A) GGSN(A) P-CSCF(A) Other xCSCFs P-CSCF(A) GGSN(B) UE(B) 1. Session Initiation 2. Prealerting 3. Pre-alerting indication 4. User interaction 5. UE(B) generates accepted SDP 6. Session Progress / Session Offering 7. Initial UMTS bearer creation 8. Ringing 9. Alerting indication 10. User interaction 11. UMTS bearer modification 12. Session Acknowle dgement 7 May 2017 IMS call setup with QoS Home Network Visited Network UE#1 P-CSCF S-CSCF 1. INVITE 2. 100 Trying 3. INVITE 4. 100 Trying 5. Evaluation of Initial Filter Criterias 6. INVITE 7. 100 Trying 9.183 Session Progress 8. 183 Session Progress 10. Authorize QoS resources 11. 183 Session Progress 12. PRACK 13. Resource Reservation 14. PRACK 18. 200 OK 19. UPDATE 17. 200 OK 20. UPDATE 23. 200 OK 15. PRACK 16. 200 OK 21. UPDATE 22. 200 OK 24. 200 OK 25. 180 Ringing 27. 180 Ringing 28. PRACK 26. 180 Ringing 33. 200 OK 32. 200 OK 29. PRACK 30. PRACK 31. 200 OK 34. 200 OK 35. 200 OK 36. Approval of QoS commit 37. 200 OK 38. ACK 7 May 2017 39. ACK 40. ACK 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 7 May 2017 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 CH REGISTER IP1 INVITE re-INVITE IP2 7 May 2017 registrar [email protected]: 128.59.16.1 REGISTER IP2 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 7 May 2017 SIP personal mobility 7 May 2017 SIP hierarchical registration 1 From: alice@NY Contact: 193.1.1.1 2 From: alice@NY Contact: alice@CA CA San Francisco NY 4 3 From: alice@NY Contact: 192.1.2.3 REGISTER INVITE Los Angeles 7 May 2017 registrar proxy 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 7 May 2017 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 7 May 2017 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 7 May 2017 Header compression 3GPP architecture 3GPP Architecture for all IP networks 7 May 2017 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 7 May 2017 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 7 May 2017 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 7 May 2017 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 only Initialization and Refresh 7 May 2017 First Order Second Order 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 7 May 2017 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 7 May 2017 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 7 May 2017 ROHC duplicate, reorder, lose packets ACK NACK • typically, multiple streams for each channel • identified by channel identifier (CID) • protected by 3-8 bit CRC 7 May 2017 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" 7 May 2017 Example: IPv6 Field Size (bits) type Version 4 static Traffic Class 8 changing Flow Label 20 static-def Payload Length 16 Next Header 8 Hop Limit 8 Src/Dest address 2x128 inferred static changing static-def inferred static 7 May 2017 2 1.5 static-def 34.5 changing 2 Example: RTP Field Size (bits) type Version 2 Padding 1 Extension 1 CSRC Counter, Marker, PT 12 Sequence Number 16 Timestamp 32 SSRC 32 CSRC 0(-480) inferred static-def static-known 7 May 2017 changing static-known static static changing changing changing static-def changing 2 bits 4 2 bits 7.5 (-67.5) 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 7 May 2017 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 7 May 2017 ROHC CRC Qiao: add one-bit correction CRC helps with BER of 4-5% Full header Decompre ssed header Compressed header Validate CRC CRC CRC Qiao 7 May 2017 Signaling compression (SigComp) Textual signaling protocols like SIP, RTSP and maybe HTTP – – – – long signaling messages ( kB) signaling delays call setup delays less of an issue: total overhead long packets headers not a major issue unlike ROHC, assume reliable transport SigComp ROHC 7 May 2017 SIP proxy Signaling compression application message & compartment id compressor dispatcher compressor 1 SigComp message compartment identifier decompressed message decompressor dispatcher state 1 state handler compressor 2 SigComp message state 2 SigComp layer transport layer (TCP, UDP, SCTP) 7 May 2017 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 7 May 2017 SigComp UDVM bytecode virtual machine with registers and stack single byte opcode + literal, reference, multitype and address request compressed data provide compressed data output decompressed data decompressor dispatcher indicate end of message UDVM provide compartment identifier request state information provide state information make state creation request forward feedback information 7 May 2017 state handler 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 7 May 2017 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 7 May 2017 ;; order pref flags service regexp replacement IN NAPTR 100 100 "s" "SIP+D2T" "" _sip._tcp.school.edu IN NAPTR 100 100 "s" "SIP+D2U" "" _sip._udp.example.com IN NAPTR 100 100 "s" "SIP+D2CU" "" comp-udp.example.com 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 7 May 2017 RTP unequal error protection RTP seq. number base E PT recovery length recovery bit mask (packets after SN base) RTP timestamp recovery 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 7 May 2017 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) 7 May 2017 UDPLite Proposal by Larzon&Degermark partial checksum coverage – at least UDP header bytes source port destination port checksum coverage UDP checksum data bytes 7 May 2017 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 7 May 2017 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 7 May 2017 MIPv6 delays Internet Internet HA 2 CH BU= HA, CoA BU= HA, CoA 2 1 3 1 Site1 Site1 CoA 7 May 2017 Castelluccia/Bellier 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) 7 May 2017 ISP1 ISP2 100' 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 7 May 2017 Ramjee 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 7 May 2017 Hartenstein et al. Cellular IP 7 May 2017 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-byhop Gomez/Campbell 7 May 2017 Cellular IP: Hard handoff home agent E C R Internet w/ Mobile IP R G R foreign agent D A B F host Gomez/Campbell 7 May 2017 Cellular IP: downlink HO loss 7 May 2017 HAWAII: Enhanced Mobile IP Internet Domain Router R R Domain Router R R R R R R R R R R MD Local mobility Mobile IP Local mobility 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 7 May 2017 Ramjee Power-up Domain Root Router 2 1 2 R3 4 Internet 1.1.1.100-> port 3, 239.0.0.1 Domain Root Router 1 1 2 R 3 4 3 4 5 1 R 4 2 3 1.1.1.100->port 4, 1 239.0.0.1 2 R 5 3 4 1 2 R 5 3 4 2 BS1 BS2 BS3 1 MY IP: 1.1.1.100 BS IP:1.1.1.5 BS4 1.1.1.100->wireless, 5 239.0.0.1 Mobile IP HAWAII 7 May 2017 Ramjee Soft-State 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 7 May 2017 Ramjee Failure Recovery Domain Root Router 2 1 2 R3 4 Internet Domain Root Router 1 1 1.1.1.100-> port 2 R 4, 3 4 239.0.0.1 3 5 1 R 4 2 3 BS1 2 1 R 5 3 4 2 BS2 BS3 1 MY IP: 1.1.1.100 BS IP:1.1.1.5 7 May 2017 1.1.1.100->port 3, 239.0.0.1 1 2 R 5 3 4 BS4 1.1.1.100->wireless, 239.0.0.1 Mobile IP HAWAII Ramjee Path Setup Schemes 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 7 May 2017 Ramjee Micro-Mobility Domain Root Router 2 1 2 R3 4 5 1 R 4 2 3 Domain Root Router 1 1 2 R 3 4 1.1.1.100-> port 3, 239.0.0.1 Internet 1.1.1.100->port 3 (4), 1 239.0.0.1 2 R 5 3 4 4 2 3 BS1 BS2 1.1.1.100->wireless, 1 5 239.0.0.1 MY IP: 1.1.1.100 BS IP:1.1.1.2 BS3 1 2 R 5 3 4 BS4 1.1.1.100->port 1(wireless), 239.0.0.1 Mobile IP HAWAII 7 May 2017 Ramjee Macro-Mobility Domain Root Router 2 1 2 R3 4 Domain Root Router 1 Mobile IP Home Agent: 1 1.1.1.100-> 2 R 4 3 1.1.2.200 Internet 1.1.2.200-> port 3, 239.0.0.1 3 5 4 5 1 R 4 2 3 1.1.2.200->port 2, 6 239.0.0.1 1 2 R 5 3 4 1 2 R 5 3 4 2 BS1 1 BS2 7 1.1.2.200->wireless, 239.0.0.2 MY IP: 1.1.1.100 BS IP:1.1.2.1 COA IP:1.1.2.200 7 May 2017 BS3 BS4 Mobile IP HAWAII Ramjee Simulation Topology 7 May 2017 Ramjee Performance: Audio and Video 7 May 2017 Ramjee TORA O'Neill/Corson/Tsirtsis "make before break" hierarchical (0,0,0,4,i) core CR (0,0,0,4,i) CR (0,0,0,5,i) CR CR(0,0,0,6,i) (-2,0,0,4,i) interior IR(0,0,0,3,i) edge IR(0,0,0,3,i) ER(0,0,0,4,i) ER (0,0,0,2,i) (-1,0,0,4,i) access AR(0,0,0,5,i) MH IR(0,0,0,5,i) IR(0,0,0,6,i) (-1,0,0,3,i) AR(0,0,0,1,i) (-1,0,0,5,i) (-2,0,0,5,i) (-2,0,0,3,i) ER (0,0,0,4,i) ER (0,0,0,7,i) AR(0,0,0,5,i) AR(0,0,0,8,i) (-2,0,0,6,i) (-2,0,0,2,i) (-2,0,0,7,i) (-2,0,0,1,i) MH (-2,0,0,0,i) 7 May 2017 Hierarchical Mobility Agents GMA RMA Home Agent LMA Localize signaling to visited domain Regional Registration/Regional Binding Update uses IP tunnels (encapsulation) only, only one level of hierarchy 7 May 2017 Perkins Example: hierarchical FA (Dynamics, HUT) CN HA Location update latencies for some transitions OLD FA FA11 FA13 FA31 HFA FA11 FA1 FA13 FA3 FA13 FA31 FA29 FA12 FA2 FA14 NEW Average FA in ms FA12 19,1 FA14 30,4 FA32 41,4 FA15 FA32 Forsberg et al 7 May 2017 Hierarchical FA with soft handoff Data stream: 100kB/s, 1kB packets (100 packets/s) CN HA HFA FA11 FA13 FA3 FA31 FA12 FA29 FA14 OLD FA NEW FA Lost packets/ update FA11 FA31 FA29 FA31 FA12 FA15 FA32 FA13 FA31 FA29 FA32 FA13 FA15 FA31 FA11 FA12 0.00 0.00 0.00 0.00 0.00 0.03 0.07 0.10 FA15 FA32 HUT Dynamics 802.11 7 May 2017 Data stream CN --> MN OLD FA NEW FA Lost packets/ update FA11 FA31 FA29 FA31 FA12 FA15 FA32 FA13 FA31 FA29 FA32 FA13 FA15 FA31 FA11 FA12 0.27 0.27 0.00 0.15 0.14 0.00 0.00 0.00 Data stream MN --> CN INRIA HMIPv6 Internet BR Site1 7 May 2017 MN MS inter-site (global, macro) vs. intra-site (local, micro) CH only aware of intersite 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? Castelluccia/Bellier INRIA HMIPv6 MH gets 2 CoA: Internet (H@,VCoA) (VCoA,PCoA) – VCoA in the MN stays constant within site – PCoA (private CoA) changes with each micromove MH registers (H@,PCoA) PCoA 7 May 2017 VCoA – (H@,VCoA) external CH – (H@,PCoA) local CHs – (VCoA, PCoA) MS MH obtains MS address and MN prefix via router advertisements INRIA HMIPv6 – packet delivery External CH sends to VCoA Internet – MS in MN intercepts and routes to MH MN MS Site1 7 May 2017 Local CH sends to PCoA INRIA HMIPv6 – micro mobility registration Internet (H@,PCoA1) (HA,PCoA) MH moves and gets new PCoA (PCoA1) sends BU (VCoA, (VCoA,PCoA) PCoA1) to its MS sends BU (H@, MS PCoA1) to local CHs PCoA1 7 May 2017 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? 3 7 May 2017 1 2 Domain1 UMTS / 802.11 "vertical" hand-off – UMTS as "background radiation" MA Domain2 4 Hartenstein et al. 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 7 May 2017 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 7 May 2017 Cost of networking Modality mode speed OC-3 P 155 Mb/s $0.0013 Australian DSL 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 P ? $62.50 P 8 kb/s $133 videoconferencing or 1/3 MP3) (512/128 kb/s) (160 chars/message) Motient 7 May 2017 (BlackBerry) $/MB (= 1 minute of 64 kb/s Spectrum cost for 3G Location what cost UK 3G $590/person Germany 3G $558/person Italy 3G $200/person New York Verizon (20MHz) $220/customer Generally, license limited to 10-15 years 7 May 2017 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 7 May 2017 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) 7 May 2017 Multimedia data access modalities bandwidth (peak) delay high low high 7DS 802.11 hotspots low satellite SMS? voice (2G, 2.5G) 7 May 2017 A family of access points 2G/3G WLAN hotspot + cache 7 May 2017 7DS Infostation access sharing 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 7 May 2017 7DS options Query Forwarding FW query query Host A Host B Host C time Querying active (periodic) passive Power conservation communication enabled on off 7 May 2017 time Dataholders (%) after 25 min high transmission power Dataholders (%) 100 P2P 90 80 P2P data sharing (power cons.) Mobile Info Server 70 P2P data sharing 60 50 P2P data sharing & FW (power cons.) Fixed Info Server 40 Fixed Info Server 30 20 10 Mobile Info Server 0 0 5 10 15 20 25 2 Density of hosts (#hosts/km ) 7 May 2017 Message relaying with 7DS WAN messages WLAN Host A Gateway WLAN Message relaying Host A 7 May 2017 Host B 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 7 May 2017 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 7 May 2017 – – – – – Ramachandran Ramjee Henning Sanneck Adam Wolisz Moshe Zukerman Kanter, Maguire, Escudero-Pascual – and others