1. NT-11 Beamforming Introduction
Month Year
doc.: IEEE /xxxxr0
May 2010
NT-11 Beamforming Introduction
Date:
Author(s):
Name
Company
Address
Phone
Abu-Surra, Shadi
Samsung
Ban, Koichiro
Toshiba
Banerjea, Raja
Marvell
Basson, Gal
Wilocity
Blanksby, Andrew
Broadcom
Borges, Daniel
Apple
Borison, David
Ralink
Chang, Kapseok
ETRI
Chu, Liwen
STMicroelectronics
Chung, Hyun Kyu
Coffey, Sean
Realtek
Cordeiro, Carlos
Intel
Dorsey, John
Elboim, Yaron
Fischer, Matthew
Giraud, Claude
NXP
Golan, Ziv
Gong, Michelle
Grieve, David
Agilent
C. Hansen, Broadcom, et. al.
VInko Erceg, Broadcom

2. May 2010 Month Year doc.: IEEE 802.11-07/xxxxr0 Author(s): Name
Company
Address
Phone
Grodzinsky, Mark
Wilocity
Hansen, Christopher
Broadcom
Hart, Brian
Cisco
Hassan, Amer
Microsoft
Hong, Seung Eun
ETRI
Hosoya, Kenichi
NEC
Hosur, Srinath
Texas Instruments
Hsu, Alvin
MediaTek
Hsu, Julan
Samsung
Hung, Kun-Chien
Jain, Avinash
Qualcomm
Jauh, Alan
Jeon, Paul
LGE
Jin, Sunggeun
Jones, VK
Joseph, Stacy
Beam Networks
Jun, Haeyoung
Kaaja, Harald
Nokia
Kafle, Padam
Kakani, Naveen
Kasher, Assaf
Intel
Kasslin, Mika
Kim, Hodong
Kim, Yongsun
Kreifeldt, Rick
Harman International
Kwon, Edwin
Kwon, Hyoungjin
Kwon, Hyukchoon
Laine, Tuomas
C. Hansen, Broadcom, et. al.
VInko Erceg, Broadcom

3. Nandagopalan, Saishankar
Month Year
doc.: IEEE /xxxxr0
May 2010
Author(s):
Name
Company
Address
Phone
Lakkis, Ismail
Tensorcom
Lee, Hoosung
ETRI
Lee, Keith
AMD
Lee, Wooyong
Liu, Yong
Marvell
Lou, Hui-Ling
Majkowski, Jakub
Nokia
Marin, Janne
Maruhashi, Kenichi
NEC
Matsumoto, Taisuke
Panasonic
Meerson, Yury
Wilocity
Mese, Murat
Broadcom
Montag, Bruce
Dell
Myles, Andrew
Cisco
Nandagopalan, Saishankar
Ngo, Chiu
Samsung
Nikula, Eero
Park, DS
Park, Minyoung
Intel
Pi, Zhouyue
Ponnampalam, Vish
MediaTek
Prasad, Narayan
Prat, Gideon
Ramachandran, Kishore
Raymond, Yu Zhan
Ronkin, Roee
Rozen, Ohad
Sachdev, Devang
NVIDIA
Sadri, Ali
Sampath, Hemanth
Qualcomm
C. Hansen, Broadcom, et. al.
VInko Erceg, Broadcom

4. May 2010 Month Year doc.: IEEE 802.11-07/xxxxr0 Author(s): Name
Company
Address
Phone
Sanderovich, Amichai
Wilocity
Sankaran, Sundar
Atheros
Scarpa, Vincenzo
STMicroelectronics
Seok, Yongho
LGE
Shao, Huai-Rong
Samsung
Shen, Ba-Zhong
Broadcom
Sim, Michael
Panasonic
Singh, Harkirat
Soffer, Menashe
Intel
Song, Seungho
SK Telecom
Sorin, Simha
Smith, Matt
Stacey, Robert
Sutskover, Ilan
Taghavi, Hossain
Qualcomm
Takahashi, Kazuaki
Trachewsky, Jason
Self
Trainin, Solomon
Usuki, Naoshi
Varshney, Prabodh
Nokia
Vertenten, Bart
NXP
Vlantis, George
Wang, Chao-Chun
MediaTek
Wang, Homber
TMC
Wang, James
Yee, James
Yucek, Tevfik
Yong, Su Khiong
Marvell
Zhang, Hongyuan
C. Hansen, Broadcom, et. al.
VInko Erceg, Broadcom

5. May 2010
Proposal overview
This presentation is part and in support of the complete proposal described in /432r0 (slides) and /433r0 (text) that:
Supports data transmission rates up to 7 Gbps
Supplements and extends the MAC and is backward compatible with the IEEE standard
Enables both the low power and the high performance devices, guaranteeing interoperability and communication at gigabit rates
Supports beamforming, enabling robust communication at distances beyond 10 meters
Supports GCMP security and advanced power management
Supports coexistence with other 60GHz systems
Supports fast session transfer among 2.4GHz, 5GHz and 60GHz
C. Hansen, Broadcom, et. al.

6. Why Beamforming? (1) 60 GHz link budget compared to 5 GHz 802.11n WLAN
May 2010
Why Beamforming? (1)
60 GHz link budget compared to 5 GHz n WLAN
Free space loss increase (-21 dB)
Decrease in TX power (~ -6 dB)
Factor of 50 increase in bandwidth (-17 dB)
Increase in RX noise figure (-3 dB)
Decrease in Maximum range (+10 dB)
Decrease in bps/Hz (+5 dB)
Net ~32 dB loss (or more) in link margin must be compensated with antenna gain at TX and RX
C. Hansen, Broadcom Corporation

7. May 2010
Why Beamforming? (2)
High antenna gains require mechanisms to point the antennas, since beamwidths will be narrow (e.g. ~13 dB gain corresponds to ~45 degree beamwidth)
Pointing must be automatic
Beamforming encompasses different techniques – switched beams, phased/weighted arrays, multiple arrays
Beamforming protocol must support interoperable devices with different technologies
C. Hansen, Broadcom Corporation

8. May 2010
Why Beamforming? (3)
Example 60 GHz conference room measurement with 18 degree beamwidth antennas
LOS channel obscured by a notebook computer (LOS path is angle 0,0)
Beamforming will find the best path automatically
C. Hansen, Broadcom Corporation

9. Beamforming Protocols
May 2010
Beamforming Protocols
802.11ad must define protocols, not algorithms
General framework and messaging are defined
Antenna specifications and beamforming adjustment algorithms are left to implementations
Our proposal employs
Directional TX / low gain (quasi-omni) RX for acquisition
Sector Sweep Phase (this presentation)
Refinement stage adds RX gain and final adjustment for combined TX and RX
Tracking during data transmission to adjust for channel changes
C. Hansen, Broadcom Corporation

10. Introduction to TX Sector Sweeps (1)
May 2010
Introduction to TX Sector Sweeps (1)
STA 2 1 3
For the initial connection between two devices (STA and AP/PCP), one will receive with a quasi-omni-directional antenna while the other sends a sequence of frames covering different TX sectors
For direct connections between two STAs in a PBSS 4
PCP
(PBSS Control Point)
C. Hansen, Broadcom Corporation

11. Introduction to TX Sector Sweeps (2)
May 2010
Introduction to TX Sector Sweeps (2)
After successfully receiving at least one sector sweep frame, the stations reverse roles and the PCP (or initiating STA) sets its antenna to quasi-omni receive and the responding STA starts a TX sector sweep.
A specific frame format is defined for the TX sector sweep
A special PHY mode (control PHY) is defined for sector sweeps. This PHY mode operates at a very low SNR (-78 dBm sensitivity) to allow robust communication with antenna gain at only one side
C. Hansen, Broadcom Corporation

12. Introduction to Sector Sweeps (3)
May 2010
Introduction to Sector Sweeps (3)
Example link budget
10 dBm TX power
64 GHz
10 meter range
TX gain 12 dB
RX gain 0 dB
Received signal power is dBm
> 11 dB margin
TX Antenna with 12 dB gain
RX Antenna with 0 dB gain
C. Hansen, Broadcom Corporation

13. Sector Sweep Packet Sequence
May 2010
Sector Sweep Packet Sequence
Each packet in the transmit sector sweep includes countdown indication (CDOWN), a Sector ID, and an Antenna ID
The best Sector ID and Antenna ID information are fed back with the Sector Sweep Feedback and Sector Sweep ACK packets
C. Hansen, Broadcom Corporation

14. May 2010
RX Sector Sweeps (1)
A device with a simple antenna may not have enough TX gain to reach a distant receiver that is using an omni-directional receiving antenna
RX Sector Sweep may be employed by the device with the higher performance antenna system
Allows a simple antenna device, like a handset, to connect at greater range 1 2
RX Sector Sweep is
used to initiate beamforming
on this link 4 3
Simple Antenna
Device
C. Hansen, Broadcom Corporation

15. RX Sector Sweeps (2) For connection to a PCP/AP using RX Sector Sweeps
May 2010
RX Sector Sweeps (2)
For connection to a PCP/AP using RX Sector Sweeps
The PCP/AP will transmit beacons using a TX Sector Sweep
Beacon will indicate:
The time when the PCP/AP will be listening for responses (A-BFT)
The PCP/AP will be listening with an RX Sector Sweep during the A-BFT
The STA will listen with its low gain antenna until it hears a beacon
The STA will respond during the A-BFT with a sequence of frames (Responder RXSS)
The PCP/AP will listen for the frames and determine the best RX Sector for communication with the STA. This sector will be employed for communication until beam refinement.
C. Hansen, Broadcom Corporation

16. Beamforming in a Service Period or TXOP
May 2010
Beamforming in a Service Period or TXOP
Beamforming may be initiated in a Service Period (SP) or TXOP
Direct links between non-PCP/non-AP STAs
Source STA of the SP (or TXOP holder) is the initiator
PCP/AP may also be the initiator or responder STA
STAs initially communicate through the PCP/AP, then beamform directly to each other for a more efficient link
Sector sweep parameters are pre-negotiated
Service Period Request (SPR) frame, Grant frame and Extended Schedule element all include the Beamforming Control Field that describes whether TXSS or RXSS is employed and the number of sectors
C. Hansen, Broadcom Corporation

17. Sector Sweep Frame Format (1)
May 2010
Sector Sweep Frame Format (1)
Section in
11-10/0433r0
Frame Control
Duration RA TA SS
SS Feedback
FCS
Octets 2 6 3 4
Direction
CDOWN
Sector ID
Antenna ID
RXSS Length
Bits 1 9 6 2
Sector Select
Antenna Select
SNR Report
Poll Required
Reserved
Bits 6 2 8 1 7
C. Hansen, Broadcom Corporation

18. Sector Sweep Frame Format (2)
May 2010
Sector Sweep Frame Format (2)
Control PHY packet (~27.5 Mbps, -78 dBm sensitivity)
17.5 microseconds
Multiple beacons in different directions are used in each Beacon Interval
Sector Sweep Frame is a Control Frame
Receiving STA learns:
MAC Address of sender
CDOWN (number of remaining frames in the sector sweep)
Sector ID
Antenna ID (particular antenna system, if device has multiples)
C. Hansen, Broadcom Corporation

19. Sector Sweep Frame Format (3)
May 2010
Sector Sweep Frame Format (3)
Initiator Sector Sweep
SS Feedback Field does not contain any information
Responder Sector Sweep
SS Feedback Field contains best sector and antenna information along with the SNR received from that configuration
C. Hansen, Broadcom Corporation

20. Sector Sweep Feedback Frame Format (1)
May 2010
Sector Sweep Feedback Frame Format (1)
Section in
11-10/0433r0
Frame Control
Duration RA TA SS
SS Feedback
BRP
Request
FCS
Octets 2 6 3 4
Same as Sector Sweep Frame
L-RX
TX-TRN-REQ
MID-REQ
BC-REQ
MID-Grant
BC-Grant
Chan-FBCK-CAP
TX Sector ID
Reserved
Bits 6 1
C. Hansen, Broadcom Corporation

21. Sector Sweep Feedback Frame Format (2)
May 2010
Sector Sweep Feedback Frame Format (2)
SS Feedback field contains best sector, antenna, and SNR information from Responder Sector Sweep
BRP Request Field contains
Specific requests for the beam refinement process that follows the sector sweep
Requests for receiver beam refinement training
Requests for specific training (MIDC/BC – described in /0450r0)
C. Hansen, Broadcom Corporation

22. Sector Sweep ACK Frame Format
May 2010
Sector Sweep ACK Frame Format
Frame format ( in 11-10/0433) is identical to Sector Sweep Feedback
Sector Sweep ACK is only used for beamforming between two non-PCP STAs in a PBSS
For beamforming with a PCP-STA, the information contained in a Sector Sweep ACK is carried in BRP frames in the beam refinement stage
C. Hansen, Broadcom Corporation

23. May 2010
Summary
Beamforming is necessary for 60 GHz systems to provide gain to compensate for additional path loss and increased system bandwidth
The ad amendment must specify interoperable protocols to enable beamforming
Sector sweeps form the foundation of a practical beamforming protocol that can be employed by many different types of implementations
C. Hansen, Broadcom Corporation