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March 2006
Rudolf, KwakSlide 1
doc.: IEEE 802.11-06/0389r0
Submission
Direct Link Management
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Date: March 6th, 2006
Name Company Address Phone email
Marian Rudolf InterDigital 1000 Sherbrooke W.
Montreal, QC, Canada H3A 3G4
+1 514 904 6258 [email protected]
Joe Kwak InterDigital 482 Degas
Bolingbrook, IL 60440
+1-630-739-4159 [email protected]
Sudheer Grandhi InterDigital
2 Huntington Quadrangle 4th Floor, South Wing
Melville, NY 11747
+1 631 622 4123 [email protected]
Authors:
March 2006
Rudolf, KwakSlide 2
doc.: IEEE 802.11-06/0389r0
Submission
Abstract
This contribution discusses management extensions to the baseline 11e DLS to allow Direct Link operation on a different channel than the BSS operating channel while maintaining BSS association and services.
This topic directly addresses:Objective 1010:Enterprise, Home, and Hot spots (managing streaming media)
Objective 2000: Dynamic Channel Selection (for new DLS links)
Objective 2030: AP Load Balancing (to offload DLS from BSS channel)
March 2006
Rudolf, KwakSlide 3
doc.: IEEE 802.11-06/0389r0
Submission
Introduction (1)• 802.11 will see huge uptake in streaming media consumer electronic
(CE) devices over the coming years.
• WiFi will appear in many new exciting CE devices.– VoIP Phones (replacing Fixed, ISM cordless and Walkie-Talkie) -DLS?– WiFi-equipped Media Adapters -DLS– WLAN Audio Playback and Distribution Systems in the home -DLS– DVD Playback and Streaming to TV through WiFi -DLS– WiFi access to centralized File Storage -DLS?– Game Consoles -DLS
• Compared to traditional pre-DLS 802.11 devices…– Access Points– PCs and Laptops– PC-peripherals– PDA-like Handhelds
March 2006
Rudolf, KwakSlide 4
doc.: IEEE 802.11-06/0389r0
Submission
Introduction (2)
• These CE devices bring new requirements to 802.11:
– Better support for QoS streams• 802.11e / WMM and 802.11n optimizations (particularly L2 efficiency of VoIP)
– Another x2-3 (and more) increase of net aggregate throughput per BSS• Current Capability in 802.11a/g = ~28-30 Mbps @ IP max best case
• in 802.11n = ~70Mbps (2x2 20MHz) or ~100Mbps (2x2 40MHz) @ IP
– Better support for battery-efficiency and power-saving• 802.11e / WMM Power Save and several more features with 802.11n
– Better >L2 protocol capabilities for IP-based service discovery and access protocols (for example, UPnP)
• Implementation and inter-operability may still need to catch up in practice…
• See 11-06-0360-00-0wng-update-on-hd-video-over-wlan.ppt which outlines new QOS issues for streaming video.
March 2006
Rudolf, KwakSlide 5
doc.: IEEE 802.11-06/0389r0
Submission
What will change with the advent of CE ?
• Much more demanding traffic types both in terms of net link throughput and QoS required – From Audio (speech and CD-quality music) to Video (DVD and HDTV)
– Increase in net throughput (at codec source) from order hundred’s Kbps max with Audio to ten’s of Mbps with Video per stream
– Delay order hundred ms’s max for streaming
– With Video, jitter and sync become stringent (down to several tens of μsec’s)
• The traffic distribution in the BSS is going to change with greater use of DLS for peer-to-peer service.– Today, bulk of both NRT and RT QoS traffic is carried ingress from STA
through AP to a remote server
– Tomorrow, a significant fraction of WLAN traffic sources (audio, video) are distributed purely inside the user’s premises, peer-to-peer
– Bulk of traffic will be intra-WLAN (rather than DS ingress/egress)
March 2006
Rudolf, KwakSlide 6
doc.: IEEE 802.11-06/0389r0
Submission
Channel capacity may limitstreaming digital video applications
• DVD to TV playback– TODAY, MPEG-2 typical in range from 3-10 Mbps (adaptive rate)– Audio and Video buffer average max 9.8 Mbit/s, peak 15 Mbits, min 300 Kbits
• Next generation DVDs– BluRay 36 Mbps basic transfer rate (and HD-DVD a little bit less than that)
• Video-recording (HD-TV to DVR using D-VHS)– High-Definition stored at ~28 Mbps, while SD stored at rates from 2-14.2 Mbps
• Watching HD-Video with ATSC (Digital Set-Top Box to HD-TV)– 19.39 Mbps (with 8-VSB) to 38.78 Mbps (with 16-VSB or 256-QAM)
• Offered load per stream at source– SDTV (UDP/IP) 4-5 Mbps– HDTV Video and Audio (UDP/IP) 19.2-24 Mbps– DV Video and Audio (UDP/IP) 28.8 Mbps
March 2006
Rudolf, KwakSlide 7
doc.: IEEE 802.11-06/0389r0
Submission
Single Channel Limitation
w/o DLS with DLS
% of channel
CE ScenarioLoad
(Mbps)
Load
(Mbps) 11 a/g 11n
1 SD DVD player (5Mbps)
Other traffic (10Mbps)20 15 50% 22%
1 SD DVD player (5Mbps)
1 HDTV receiver (25Mbps)
Other traffic (10Mbps)
70 40 133% 57%
1 SD DVD player (5Mbps)
1 HD Video Cam (25Mbps)
1 HDTV receiver (25Mbps)
Other traffic (10Mbps)
120 65 217% 93%
March 2006
Rudolf, KwakSlide 8
doc.: IEEE 802.11-06/0389r0
Submission
(1) Peer-to-peer traffic with BSS only (no 11e DLS)
Mpeg TS over WLAN
HD Plasma Monitor
HD Plasma Monitor
Bedroom 1 Bedroom 2
Living Room
HDTV Receiver 1
HD Plasma Monitor
HDTV Receiver 2
Media Server
Access Point
Source: slightly modified from 11-05-0910-01-0wng-802-11-video-transmission
BSSID “Home”
March 2006
Rudolf, KwakSlide 9
doc.: IEEE 802.11-06/0389r0
Submission
(2) Peer-to-peer traffic with BSS and 11e DLS
Mpeg TS over WLAN
HD Monitor
HD Monitor
Bedroom 1Bedroom 2
Living Room
HDTV receiver+ PVR
Live HDTV Channels
HD Monitor
DVD videoVideocam
content
Portable DVD Player
HD video camera
Access Point
BSSID “Home”
Source: slightly modified from 11-05-0910-01-0wng-802-11-video-transmission
Direct Link 1 Direct Link 2
Direct Link 3
Direct Link 4
March 2006
Rudolf, KwakSlide 10
doc.: IEEE 802.11-06/0389r0
Submission
(3) Peer-to-peer traffic with multiple BSSs
Mpeg TS over WLAN
HD Monitor
HD Monitor
Bedroom 1Bedroom 2
Living Room
HDTV receiver+ PVR
Live HDTV Channels
HD Monitor
DVD videoVideocam
content
Portable DVD Player
HD video camera
Access Point
BSSID “Home”
Source: slightly modified from 11-05-0910-01-0wng-802-11-video-transmission
BSSID “V1” BSSID “V2”
BSSID “V3”
BSSID “V4”
March 2006
Rudolf, KwakSlide 11
doc.: IEEE 802.11-06/0389r0
Submission
Peer-to-Peer: DLS vs IBSS
• “Peer-to-Peer” must not to be confused with the question of BSS vs. IBSS mode– Peer-to-peer traffic is about devices sending data to other devices in part of the same L2
network, i.e. it is not DS ingress/egress traffic– BSS vs. IBSS is about how an 802.11 network is actually organized at L2– In 802.11, any client can send traffic to any other client in the BSS or IBSS
• IBSS for peer-to-peer is unpractical and only a remote theoretical possibility– 11i, credential provisioning and security one of the reasons
• Peer-to-peer clients will also need access to the Internet through the BSS, making BSS mode the only practical approach with 802.11– Example: Retrieve and display live artist info when streaming MP3’s from a centralized
file server to audio distribution system
March 2006
Rudolf, KwakSlide 12
doc.: IEEE 802.11-06/0389r0
Submission
Proposal: alt-channel DLS• Provisions to better accommodate peer-to-peer traffic and high-throughput
links would address important 802.11 needs for CE– Streaming video the prime example
• Problem today is basic bandwidth, QoS, delay and sync limitations for high-throughput peer-to-peer links that will persist even with 11n
• Increasing available bandwidth for the link beyond the barely necessary can usually be traded off against sophisticated provisions to better guarantee QoS, delay and jitter
• Permit DLS operation on alternate channel than BSS channel:– Could allow these devices to go off the regular BSS channel and Tx intermittently
and under control of the AP on a different peer-to-peer channel– Devices keep their association and basic L2 connectivity within the BSS (11i)– Avoid performance issues with interference ranges compared to operating on the
BSS channel only– Increases the de-facto available channel bandwidth for all devices in the BSS
March 2006
Rudolf, KwakSlide 13
doc.: IEEE 802.11-06/0389r0
Submission
• Use 11e DLS protocol managed on alt channel in multi-channel BSS
Outline for alt-channel DLS operation
Channel 1 (BSS) Channel 1 (BSS)
Channel 6(peer-to-peer DLS traffic)
Switch timeBSS channel sync schedule
QSTA1, QSTA2 and QAPQSTA1, QSTA2 and QAP
QSTA1 and QSTA2QSTA1 and QSTA2
Channel 1 (BSS)
Channel 6 (DLS)
March 2006
Rudolf, KwakSlide 14
doc.: IEEE 802.11-06/0389r0
Submission
Other protocol elements in support ofalt-channel DLS operation
• Sync schedule for the BSS channel between AP and the peer DLS STAs– Impose the burden of implementation on STA rather than the BSS (?)
– Maintain ability to send/receive management and DS data
• Will probably need an additional, more refined timer sync mechanism for the peer-to-peer link to meet video-grade requirements– Only the peer devices will need tight sync amongst themselves, no need to
impose such a burden on other devices in the BSS
– AP keeps BSS (peer-to-peer devices amongst them) synced-up through Beacon timing as today
• Several extensions to TSPEC’s and their negotiation– Fixes to address latency, jitter and allow for short-terms traffic prioritization
– Support for multiple parallel streams
• Others?
March 2006
Rudolf, KwakSlide 15
doc.: IEEE 802.11-06/0389r0
Submission
Conclusions
• CE devices with high data rate streaming media are emerging now.
• Single channel capacity may limit devices, even with DLS.
• TGv management improvements for DLS can provide solutions.
• TGv should consider alternative solutions and begin work.
March 2006
Rudolf, KwakSlide 16
doc.: IEEE 802.11-06/0389r0
Submission
References
1) 11-05-0910-01-0wng-802-11-video-transmission
2) 11-05-0887-00-000t-video-testing-strategy
3) 11-05-1194-00-000t-video-testing-methodology-ged
4) 11-06-0322-00-000t-overview-video-use-cases
5) 11-06-0321-00-000t-ged-video-over-wireless-methodology
6) 11-06-0144-01-000t-video-over-wireless-methodology
7) 11-06-0039-01-0wng-video-over-802-11
8) 11-06-0360-00-0wng-update-on-hd-video-over-wlan.ppt
March 2006
Rudolf, KwakSlide 17
doc.: IEEE 802.11-06/0389r0
Submission
Thank you !
March 2006
Rudolf, KwakSlide 18
doc.: IEEE 802.11-06/0389r0
Submission
Straw polls
• Straw poll 1 (alt-channel DLS)– Do you feel that multi-channel operation in the BSS such as
described for the specific case of DLS would be in-scope of TGv ?
• Straw poll 2 (multi-BSS home environment)– Do you feel that extensions to the existing inter-AP TGv work item
(for example inter-AP discovery and extensions to WDS) such as described in Scenario 3 would be worthwhile to pursue in TGv ?
