doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Slide 1 Technology and Use Cases for TGac Authors: Date:

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Introduction We look at various technologies for TGac, map the technologies to use cases and conclude that most of the gain is achieved with simple extensions to TGn For use cases, we reference –WiFi Alliance (WFA) VHT Study Group Usage Models presented in 07/2988r4 Slide 2

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Possible technologies Wider channels Higher order modulation and code rate More spatial streams Multi-user MIMO OFDMA

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Wider Channels Possible approaches –Bond adjacent channels to form 80 MHz channel –Simultaneous transmission on non-adjacent channels Advantage –Doubles the PHY data rate (sticker on the box still sells) –Negligible increase in cost over 11n Issues –Bonding Coexistence with 11n 20MHz & 40MHz –Non-adjacent channels Significant receiver complexity to deal with OBSS –Frequency reuse The number of available non-overlapping bonded channels will be lower –One 80MHz channel in GHz band –One 80MHz channel in GHz band Can increase co-channel interference –Unknown whether a single channel can span multiple regulatory bands

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Higher order modulation and code rate Higher order modulation –256 QAM (was almost adopted in 11n) –1024 QAM Higher code rate –7/8 (was almost adopted in 11n) Advantage –Architecturally simple addition to the standard Issues –Reduces robustness –Requires tighter Tx and Rx specs (e.g. phase noise)

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 More Spatial Streams Go beyond four steams in 11n, perhaps eight Advantage –data rate increases as a function of number spatial streams Issues –Size/power constrained devices may not be capable of supporting additional antennas –Antenna correlation/coupling if antennas need to be packed closer together –As we have seen in 11n, mobile/portable devices unlikely to support a large number of antennas

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Multi-user MIMO 11n MIMO –Spatial division multiplexing (SDM) – STA simultaneously transmits multiple streams to another STA Multi-user MIMO –STA simultaneously transmits multiple streams to several other STAs E.g. 4 antenna AP transmits two streams to STA1 and two streams to STA2 Advantage –Increases network capacity with client devices that only have few antennas Issues –Multi-user MIMO on the downlink from AP to STA has higher complexity than 11n Tx Beamforming –Multi-user MIMO has very high complexity on uplink - would require precise transmit packet synchronization between STAs and transmit power control (similar to that required in CDMA cellular system) –Scheduling –As yet not well know how time variant is the channel

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 OFDMA Subdivide OFDM subcarriers to several STAs –Used in cellular systems like Wimax Advantage –More efficient method in usages with multiple lower rate clients, e.g. voice –Efficient uplink technique for ACK packets in response to downlink MU- MIMO packet Issues –Has very high complexity on uplink - would require precise transmit packet synchronization between STAs and transmit power control –Scheduling –Does not increase maximum data rate or network capacity, only improves efficiency with multiple lower rate clients

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, a1c 1b 2a2b 1d3b 1a 6a2d 3d 4a 4b 3e 2c 1f 5b 1e 5a 2e3c WFA VHT Usage Models mapped to market volume and timing* Anticipated Market Timing For Mainstream Market Market Volume Rela- tively Low Sooner Relatively High Later Highlight these use cases on the next slide * from 07/2988r4

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Slide 10 WFA VHT Usage Models mapped to technologies Category#Usage modelMCS Wider channel MU- MIMO OFDMAMore SS 1. Wireless Display1aDesktop Storage & DisplayXX? 1bProjection to TV or projector in conf room (lightly compressed video)XXX 1cIn room gaming (lightly compressed video)XXX 1dStreaming from camcorder to display (lightly compressed video)XX 1eBroadcast TV field pick upX 1fMedical Imaging and Surgical Procedure SupportXX 2. Distribution of HDTV 2aLightly compressed video streaming around the homeXXX 2bCompressed video streaming around homeXXXX 2cIntra large vehicle (e.g. airplane) applicationsXXX? 2dWireless networking for officeXXX 2eRemote medical assistanceXX 3. Rapid upload/download 3aRapid sync-n-go file transferXX 3bPicture by picture viewingXX 3cAirplane dockingXX 3dMovie content download to carX? 3ePolice / surveillance car uploadX? 4. backhaul4aMulti-media mesh backhaul??X 4bPoint-to-point backhaulXX 5. Outdoor campus / auditorium 5aVideo demos / tele-presence in auditoriumXX 5bPublic safety mesh??X 6. Manufacturing floor6aManufacturing floor automation???

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Short range applications Some of the most important usage models are short range –1a: Desktop storage and display –1b: Projection to TV or projector –1c: In-room gaming –1d: Streaming from camcorder to display –3a: Rapid sync-and-go file transfer –2d: Wireless networking for office These applications benefit from MCS enhancement (in addition to wider channels)

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Video streaming around home Most video streaming applications are best supported using direct links Relay through AP is unlikely to be as efficient even with MU-MIMO In some scenarios, downlink MU-MIMO may be beneficial for multiple streams (but again using direct link) TV DVR PC

doc.:IEEE /0789r1 Submission Robert Stacey, Intel July 13, 2009 Summary Wider channel benefits almost all applications –2x improvement MCS enhancements benefit short range, direct link applications –Almost 2x improvement possible Downlink MU-MIMO provides increased network efficiency for some applications –Only when long term, simultaneous traffic flows are present (e.g. video) –< 2x improvement; dependent on uplink/downlink traffic mix –Not clear that 2 hop MU-MIMO is better than direct link More spatial streams may provide some benefit in certain environments –Cost and form factor prohibitive for most devices due to antenna requirements Downlink OFDMA provides little benefit –Power saving and performance gain questionable Uplink space/frequency multiplexing techniques –No compelling use case, especially considering complexity