WiGig and HaLow - Wi-Fi at new Frequency Bands

WiGig and HaLow –
Wi-Fi at New Frequency Bands
April 19th, 2017
Veli-Pekka “VP” Ketonen
@VPonwireless

WiGig and HaLow at a glance
WiGig / 802.11ad
• Operates in the 60 GHz frequency band
• Wireless docking and HD video
connections
• Seamless handoffs between bands
• Up to 6.75 Gbit/s data rates
• Adjusted 802.11n MAC with more
spectrum bandwidth, no-MIMO
• Standard ready, first products in the
market
Halow / 802.11ah
• In US, operates in the 915 MHz ISM band
• IEEE wide area IoT standard
• 150kbit/s - 234 Mbit/s data rates
• 802.11ac PHY with carrier bandwidths cut
down by 10x, up to 4 SS
• Adding new innovative MAC features of
which many are included to 802.11ax
• IEEE Standards Board approved in Dec
2016, no commercial products available

3
Spectrum bandwidth with different Wi-Fi standards

4
WiGig and HaLow market positioning
Björn Ekelund, Ericsson
https://www.slideshare.net/bjornopekelund/technologies-for-the-internet-of-things?qid=362d13c5-ccb1-4a7c-bd99-0fe7a3908d4e&v=&b=&from_search=9
IoT

WiGig/802.11ad, deeper dive
Graphics, ABI Research, 2016
https://www.qualcomm.com/documents/abi-research-80211ad-will-vastly-enhance-wi-fi

7
Use cases
7
ABI Research, April 2016

802.11ad PHY overview
• Directional Multi-Gigabit (DMG) PHY
• Three modes
• Control PHY
• Low SNR operation prior to beamforming
• 27.5 Mbit/s, DSSS π⁄2-BPSK
• 10 dB better sensitivity than SC PHY
• Single Carrier (SC) PHY
• Low power, low complexity
• Up to 16 QAM, 4.62 GBit/s (MCS 12)
• OFDM PHY (optional)
• High performance
• Up to 64 QAM, 6.75 Gbit/s (MCS 24)
• No MIMO
• Bi-directional beamforming
• Preamble training with Golay sequences
9
Eldad Perahia, Michelle X. Gong
https://pdfs.semanticscholar.org/b2d7/a3feddbeffa2ce1001c2e673f79e581094bf.pdf
Raj Jain, Washington University in St. Louis
http://www.cse.wustl.edu/~jain/cse574-14/ftp/j_07sgh.pdf

10
Data rates/MCSs
Single Carrier and Control rates
OFDM rates
https://en.wikipedia.org/wiki/Wireless_Gigabit_Alliance#cite_note-28
Low-power single-carrier data rates not shown
Control traffic
uses MCS0
BPSK
QPSK
16QAM

11
Channelization
11
John Harmon, Keysight
http://www.keysight.com/upload/cmc_upload/All/22May2014Webcast.pdf?&cc=US&lc=eng

12
Beamforming with with antenna array
Silversima Inc., product brief
https://siversima.com/wp-content/uploads/PB_TRX-BF01_v1.pdf
Eldad Perahia, Michelle X. Gong
https://pdfs.semanticscholar.org/b2d7/a3feddbeffa2ce1001c2e673f79e581094bf.pdf

13
Range and maximum throughput
13
Thomas Nitsche et. al., IMDEA Networks Institute/Universidad Carlos III
http://networks.rice.edu/files/2014/10/11adPaper.pdf
RF link:
1m free path loss is 21 dB higher (68 dB vs 47 dB)
Noise floors is 17 dB higher due to 2 GHz BW
Appr. 12 dB antenna gain available at both ends

15
802.11ad MAC overview
• Directional antenna patterns used at both
ends
• Ad hoc like selection of controlling device
• Transmissions are centrally scheduled
• Beam training and tracking is essential
• Beacons need to be swept to all directions
• Multiple simultaneous transmission at the
same frequency are possible
• Relays can be used if LoS is blocked
15

16
Personal Basic Service Set (PBSS) and
PBSS Central Point(PCP)
• Personal Basic Service Set (PBSS)
• Group of stations that communicate
• PBSS Central Point (PCP)
• Provides airtime coordination/scheduling and timings using beacons
• Ad hoc method used for determining PCP
• Only PCPs transmit beacons
• Overlapping PBSS avoid interference by electing a Synchronization PCP (S-
PCP) for the PCP cluster
• PCP handover supported

17
Beacon Interval super-frame
Each Beacon Interval is divided in to four main parts
1. Beacon Time (BT)
• New station discovery. Only PCP can send beacons during beacon time
2. Associating Beamforming Training (A- BFT)
• PCP performs antenna training with its members
3. Announcement Time (AT)
• PCP polls members and receives non-data responses (association,…)
4. Data Transfer Time (DTT)
• All stations exchange data frames in a dedicated service period (SP) or
• by contention in contention-based period (CBP)
Beacon format Beacon antenna sweep

18
Hybric MAC, scheduled and contention based
• Two different channel access methods
• Dynamic channel time allocation
• During Service Periods, SPs
• Scheduled centrally controlled transmissions (PCF mode extension)
• All stations exchange data frames in a dedicated service period (SP)
• More flexible. Stations get channel time, not just one frame
• Contention based medium access
• During Contention-Based Periods, CBPs
• Hybrid TDMA-CSMA based on EDCA
• Physical Carrier Sense / Virtual Carrier Sense
• NAV, QoS, frame aggregation, block ACKs
• Directional Band CTS (DBandCTS), DBand Denial to Send (DBandDTS), DBandCF-End
• NAV for each source-destination pair
• Pseudo-static TDMA channel time allocation
• Service period may be allocated semi-permanently to a pair of nodes

19
Beamforming
19
Robert W. Heath Jr., The University of Texas, Austin
https://web.stanford.edu/~apaulraj/workshop70/pdf/mmWaveMIMO_Heath.pdf

20
FST and Relay operation
• Fast Session Transfer (FST)
• Seamless integration of 60 GHz with other bands for multiband devices
• FST allows transition from any band/channel to any other band/channel
• Simultaneous and non-simultaneous operation supported
• Transparent operation keeps MAC address unchanged, non-transparent alters
the address
• Relay operation
• Switch relay
• From source to destination
• Co-operation relay (hub, repeater)
• Amplify and Forward (AF)
• Decode and Forward (DF)
• Direct and relayed signal may both be used for spatial diversity
20

21
802.11ay (WiGig2) improves 802.11ad/WiGig further
• Objective
• > 20 Gbit/s throughput
• Technologies
• Channel bonding
• MIMO
• Backwards compatibility with -ad
• To be completed in 2019
21
Dorothy Stanley, Hewlett Packard Enterprise
https://www.ietf.org/edu/documents/95-802-11-Tutorial.pdf
ABI Research, April 2016

22
Multiplexing techniques in 802.11ad
22
Channel
OFDM with 1
spatial stream
High attenuation
at 60 GHz
Bi-directional high
gain beam steering
Scheduled service
periods and
contention based
periods
Fast session
transfer with
simultaneous
operation
Relay with
combining

24
Access points with WiGig support, examples
24
TP-Link AD7200 Wireless Wi-Fi
Tri-Band Gigabit Router (Talon
AD7200)
NETGEAR Nighthawk X10 –
AD7200 802.11ac/ad Quad-
Stream MU-MIMO WiFi Router Acelink BR-6774AD
Marketed AP class specification:
Up to 4620 Mbit/s for a single channel in the 60 GHz 802.11ad
Up to 1733 Mbit/s for four 802.11ac Wave2 5 GHz,
Up to 800 Mbit/s for four-channel 802.11n 2.4 GHz
Note: These are Single Carrier (SC) devices

25
Terminals with WiGig support, examples
http://www.networkworld.com/article/3117803/computers/acer-
travelmate-802-11ad-notebook-an-industry-first-you-might-never-
need-or-use.html
60 GHz WiGig (802.11ad) wireless docking
connectivity for mobile client device (2 in 1,
tablet, laptop) with up to 4.7 Gbps of
bidirectional throughput.
http://www.intel.com/content/www/us/en/wireless-
products/tri-band-wireless-ac-wigig-18260-product-
brief.html
http://www.androidauthority.com/le-max-pro-will-be-the-
first-phone-with-snapdragon-820-ultrasonic-sensor-and-
wifi-802-11ad-665995/
LeTV Le Max Pro
Qualcomm Snapdragon 820
The first phone with WiGig
No availability in US
Some phones with the latest
Qualcomm Snapdragon 835
expected to have WiGig support

26
Wi-Fi Alliance certified WiGig products (4/13/2017)
Wi-Fi Alliance 802.11ad certified products
http://www.wi-fi.org/product-finder-results?sort_by=certified&sort_order=desc&certifications=62
Dell Latitude 7480

27
Measured performance (Tim Higgins, SmallNetbuilder)
• TP LINK Talon AD7200 Multiband router (2.4, 5, 60 GHz)
• Acer TravelMate TMP446-M-77QP notebook (802.11ad support)
• Measured maximum about 1500 Mbit/s with dual 2 Gbit/s Eth capacity
Tim Higgins, SmallNetBuilder
https://www.smallnetbuilder.com/wireless/wireless-reviews/33009-tp-link-talon-ad7200-multi-band-wi-fi-router-reviewed?start=3

28
Market forecasts for WiGig
28
ABI Research, 2016
Wi-Fi chipset shipments by number of bands Total single band and multiband 802.11ad
Wi-Fi chipset shipments by product category

30
Wi-Fi needs improvements to be IoT ready
Total number of IoT devices is expected to be 50 billion by 2020*
while in “traditional” Wi-Fi
• MAC overhead is significant especially with small packets
• Consumes too much energy for long term battery operation
• Cannot handle many thousands of stations/AP
• Coverage is not sufficient for IoT use
* D. Evans, The Internet of Things – how the next evolution of the Internet is changing everything,
Cisco Internet Business Solutions Group (IBSG), 2010
Number has been later lowered to 20 - 30 billion devices by 2020

32
Use Case 1 : Sensors and meters
Rolf de Vegt, Qualcomm Atheros
http://www.comsocscv.org/docs/IEEE%20ComSoc_11ah_Opportunity_V6_0715.pdf

33
Use Case 2 : Extended range Wi-Fi

34
Examples of potential 802.11ah devices, per segment

36
802.11ah PHY overview
• S1G PHY based on 802.11ac with 1/10 clock rate
• Spectrum bandwidths are divided by 10
• 160 MHz -> 16 MHz
• 20 MHz -> 2 MHz
• 1 MHz channel width is a special case. It has 32 subcarriers
• OFDM symbol 10x longer
• Mandatory PHY features
• 1, 2 MHz channel widths
• Single spatial stream
• Repetition for 1 MHz MCS10
• Optional PHY features
• 1, 2, 4, 8 & 16 MHz channel widths
• Four spatial streams
• STBC & LDPC coding
• Beam sounding
• Short Guard Interval
• Traveling pilots

37
Data rates and bandwidths
16 MHz
8 MHz
4 MHz
2 MHz
1 MHz
20 MHz
Minimum 11n/ac bandwidth
11ah Bandwidth Modes
Higher
Data
Rates
Extended Range
150Kbps – 4Mbps
650Kbps – 7.8Mbps
1.35Mbps – 18Mbps
2.9Mbps – 39Mbps
5.8Mbps – 78Mbps
Mandatory &
Globally
Interoperable
modes optimized
for sensor
networking
Optional higher
data rate modes
for extended
range Wi-Fi
6.5Mbps – 78Mbps
Note : Single spatial stream and Long
Guard interval data rates displayed
> 1000m
4SS, 4us SGI
=> 234 Mbit/s
IEEE-SA IoT workshop 802.11ah Overview

38
Spectrum allocations and RF power

39
Traveling pilots and pilot boosting
• In outdoor case, a reflection from moving
vehicle may cause Doppler shift. This degrades
receiver capability to decode signal properly
• Current 802.11 system only allow channel
estimation in the beginning of the frame during
the Long Training Field (LTF)
• Traveling pilots allow continuous refresh of
channel estimation take during the frame
transmission
• Pilot signal level boosting further improves
channel estimation
Mathworks, Inc.
https://www.mathworks.com/help/wlan/examples/802-11ah-waveform-
generation.html?requestedDomain=fr.mathworks.com

40
802.11ac vs. 802.11ah PHY
Keysight Inc.
http://www.keysight.com/upload/cmc_upload/All/IoT_Seminar_Session1_Explosion_of_the_Internet_of_Things.pdf?&cc=US&lc=eng

42
802.11ah MAC overview
• 802.11ah MAC adds many
innovative improvements
• Operating on a different band
removes the need for the MAC to
be completely backward
compatible
42
Victor Baños-Gonzalez et. al. IEEE 802.11ah: A Technology to Face the IoT Challenge
http://www.mdpi.com/1424-8220/16/11/1960

43
Restricted Access Window (RAW)
• Simple scheduling scheme
• In beacons, AP assigns a group of
devices to certain time slots
• Devices can access the channel only
during the assigned timeslot
• Devices contend for medium access
within the slot with EDCA
• RAW decreases probability of
collisions with thousands of devices
• RAW also enhances power efficiency
since stations can sleep during alien
slots
Orod Raeesi et. Al., Tampere University of Technology
https://www.researchgate.net/publication/269273626_Performance_Enhancement_and_Evaluation_of_IEEE_80211ah_Multi-
Access_Point_Network_Using_Restricted_Access_Window_Mechanism
Throughput for 9 APs case Energy efficiency

44
Response Indication Deferral (RID) and
Bi-Directional TXOP (BDT)
Response Indication Deferral (RID)
• New simpler virtual carrier sense
• NAV not supported due to frame efficiency improvement
• RID is countdown like NAV. RID can be updated to shorter value during
count down, unlike NAV
• RID estimates durations to achieve better efficiency
Bi-directional TXOP (BDT), speed frame exchange
• Station and AP can exchange frames within one TXOP
• Implicit reception without ACK
• Faster exchange, reduces overhead, eliminates contention, saves energy

45
BSS coloring
• A technique to improve co-existence of
overlapping BSSs (OBSS) and allow
spatial reuse within one channel
• Each BSS (SSID) is assigned a specific
“color” identifier
• Frames from neighbor SSIDs can be
treated differently when assessing
channel availability (Clear Channel
Assessment, CCA)
• Increases channel availability
Dorothy Stanley, Hewlett Packard Enterprise
https://www.ietf.org/edu/documents/95-802-11-Tutorial.pdf

46
Group sectorization
• A method for space – time multiplexing
within one channel
• Stations at the opposite ends of the AP
coverage area cannot hear each other and
number of stations can be very high
• Location aware grouping allows
simultaneous operation for stations inside
one sector interval
• Group sectorization and RAW further
complement each other
• Antenna beam forming or similar capability
is needed. It’s implementation is not
standardized
• Benefits include improved quality, capacity
and power efficiency
Muhammad Qutab-Ud-Din, Tampere University of Technology
http://dspace.cc.tut.fi/dpub/bitstream/handle/123456789/23538/Qutabuddin.pdf?sequence=1

47
Sub-channel Selective Transmission (SST)
• 802.11ah standard allows operation with up to 16 MHz channels
• Standard mandatory supported channels are 1 MHz and 2 MHz
• Sensors will prefer to use narrow channels for reduced energy
consumption
• Narrower channels are more likely to experience and suffer from deep
fading
• SST allows stations to rapidly select and switch to different channel
widths and channels between transmissions to counter fading over
narrow sub-channels
Evgeny Khorov et. al. IITP RAS
http://infonet.cse.kyutech.ac.jp/lecture/graduate/doc/sensor.pdf

48
Relay
• Relay AP and Relay station needed
• APs and stations can operate as relays
• 802.11s Mesh is too complex for IoT
purpose
• Max two hops
• Relay discovery by station
• Two hop TXOP sharing when using
the same channel
• Flow control to avoid buffering
• Benefits
• Extend range
• Improve reliability
• Reduce energy consumption

49
Mac efficiency and energy saving improvements
• Association Identifier (AID) maximum increased from 2007 to 8192 stations
• Grouping of stations with similar characteristics, 4 level AID structure
• Fast association and authentication supporting thousands of stations
• Short frames to reduce active TX/RX time
• Short MAC header
• Short beacon frame (and compressed TIM) to reduce beacon decode times
• Short probe request/response
• Short control frames
• Increased standby time: Expand listen and MAX BSS idle periods to allow STAs sleep for
hours/day. Idle times increased from 18.64h up to a year
• Target Wake Up Time (TWT) allows station sleep also over beacons over longer times
• Enable AP and relay nodes to sleep
• Client timing relaxation, useful for battery operated devices
• Maximum awake interval, Recovery time

50
Multiplexing techniques in 802.11ah
50
Channel with
SST
OFDM with 4
spatial streams
Restricted
Access Window
with EDCA
4 level
hierarchical
device groups
Group
sectorization
BSS color
Relay

51
802.11ah performance, outdoor
51
7x coverage improvement
vs. VHT20 –ac
Outdoor up to 1500m,
indoor 1000m
Victor Baños-Gonzalez et. al., Universitat Politècnica de Catalunya BarcelonaTech
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134619/pdf/sensors-16-01960.pdf

53
Products
• No products yet available
• Cadence silicon design vendor offers 802.11ah functionality for integration to their
customer chips
• 900 MHz 802.11ah functionality is expected to be added to Wi-Fi access points and
routers
• -ax borrowed from -ah
• Scheduling
• BSS Coloring
• Traveling pilot
• Target Wake up time (TWT)
• Only narrow band (20 MHz) channels mandatory for 5 GHz
53

54
Summary
HaLow (802.11ah) WiGig (802.11ad)
Standard Approved in Dec 2016 Approved in Dec 2012
802.11ay expected in 2019
Purpose Wi-Fi IoT standard Very high throughput
Use cases 1. Sensor networking
2. Wearables
3. Industrial automation
4. Utility networking
5. Extended range Wi-Fi
1. Wireless display/audio
2. HDTV distribution
3. Wireless docking station
4. High capacity backhaul
5. Cordless computing
PHY 902-928 MHz (US)
1 MHz – 16 MHz, 1-26 channels (US)
150kbit/s - 234 Mbit/s (4 SS)
Up to 4 spatial streams
57240 MHz – 63720 MHz (US)
2160 MHz, 4 channels (US)
27.5 Mbit/s – 6.75 Mbit/s
1 spatial stream
MAC 802.11 + several improvements for high amount of
terminals and lower power consumption
Many improvements are reused in -ax
802.11 + several improvement to operate with a ray like
beam steering links and associated “deafness”
Seamless transitions between bands
Deployment model Add HaLow radios to upcoming APs
IoT sensors support only –ah standard
Add WiGig radios to upcoming APs and terminals
Products Not yet available One laptop and a few AP models
Several PCIe radio cards

Thank You!
veli-pekka.ketonen@7signal.com
Twitter: @VPonwireless

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