Standardization of BLE-based Connectionless AoA

Presentation info
Location : 99J9+H2 Yuseong District, Daejeon (maps.google.com)
Date : Feb 24, 2020

1. GCT Semiconductor, Inc.
Things to be considered for the Standardization of
Connectionless Angle-of-Arrival with BLE devices
(v4.x & v5.1)
Ealwan Lee
GCT Semiconductor, Inc.
Feb 24, 2020

2. GCT Semiconductor, Inc.
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Agenda
❑Introduction
◆Status of Bluetooth-SIG
❑Connectionless DF features of Core-v5.2 and HCIs
◆Periodic Advertising Channel
❑Review of CTES, ATP
◆Comparison with IPS-1.1 & IPP stuck at validation phase(IOP)
❑Validation Phase (IOP)
◆TS, BTI
❑Schedule to be monitored during the standardization of SDCP
◆Review, Approval, Adoption of CTES(+ATP) by BARD & BOD
❑Information on Non-standard Connectionless AoA
◆Quuppa
❑Collaboration
◆CATS, IOP for SDCP
❑Summary
pp. 03 ~ 17
pp. 18 ~ 23
pp. 24 ~ 27
pp. 34 ~ 37
pp. 40 ~ 40
pp. 38 ~ 39
pp. 02 ~ 02
pp. 28 ~ 33

3. GCT Semiconductor, Inc.
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Advertising Channel Packet Format with CTE
❑Constant Tone Extension(CTE) is appended to the CRC of AUX_SYNC_IND.
p. 2871
p. 2871
p. 2865
p. 2872

4. GCT Semiconductor, Inc.
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Which state should be used - Periodic advertising state w/ CTE
❑Periodic advertising state of advertising state
◆Introduced since v5.0
◆CTE is allowed only in perodic advertising pdu.
p. 3111 of Core-v5.2
#1
#2
#3

5. GCT Semiconductor, Inc.
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Advertising Extension : Major improvement in v5.0
❑In v4.x,
◆All the payload in three advertising PDU does not changer over the channels.
❑In ADV_EXT_IND of v5.x,
◆part (AUX_PTR) of payload change over the channels.
advertising
PDU (#37)
(ADV_EXT_IND)
primary
advertising
channel
secondary
advertising
channel
advertising
PDU (#38)
advertising
PDU (#39)
AUX_ADV_IND
connectionless AoA part
(much longer if required)
Tag->broadcast
Tag->broadcast
Tag->broadcast
Tag->broadcast
AUX_PTR
(#37)
AUX_PTR
(#38)
AUX_PTR
(#39)
Only 1 Mbps is allowed. 1 Mbps or 2 Mbps

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CTE appended to AUX_SYNC_IND PDUs.
❑AUX_SYNC_IND has already been introduced since v5.0.
◆DF feature of CTE has been introduced since v5.1
AUX_ADV_IND AUX_SCAN_REQ
secondary
advertising
channel
(1 or 2 Mbps)
AUX_SYNC_IND
Loc->Tag
Tag-> broadcast
periodic
advertising
channel
(1 or 2 Mbps)
primary
advertising
channel
(1Mbps only)
ADV_EXT_IND
(#39)
Tag-> broadcast
AUX_PTR
(#93)
SYNC_INFO
Tag-> broadcast
pre-whitened CTE
for connectionless HADM
CTE
#1
#2
#3

7. GCT Semiconductor, Inc.
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HCI command and event for Connectionless AoA
❑HCI requires sync_handle for the argument.
Immediate
return
After collecting
I/Q samples of
periodic sync packet
Informations
required for AoA estimation

8. GCT Semiconductor, Inc.
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Slot for antenna switching in CTE duration.
❑A tone generated by consecutive transmission of all 1’s (whitening bypassed)
❑Why switching of antenna in both Tx and Rx(AoA+AoD) cannot be carried out ?
◆Clock frequency offset between tag(Tx) and locator(Rx).
p. 2915
= max of CTETime

9. GCT Semiconductor, Inc.
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I/Q sample format
❑Only A single pair of 8-bit (I, Q) is reported per slot(1us or 2us).
❑Abstraction independence of
IF frequency(0, +2, ... )
ADC sampling frequency
is achieved partially with Sampling Window.
p. 2420
Identical Sampling Window
should be applied also to the reference period.
p. 2917

10. GCT Semiconductor, Inc.
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Pre-requisite for the measurement of phase difference
❑Frequency offset estimation and compensation
◆Only with sampled 8 I/Q samples
◆Phase offset compensation is optional
◆Symbol timing/phase offset cannot be done only with reference period of CTE.
❑Each single I/Q pair should be best pre-processed with all the Rx implementation.
◆Simple sampling or summation results in significant performance degradation.
r0, r4
r1, r5
r2, r6
r3, r7
a0[0], a0[2]
a0[1], a0[3]
a1[0], a1[2]
a1[1], a1[3]
phase difference of arrival AoA
I
Q
Case :
8 Msps
1 Mbps
+
+

11. GCT Semiconductor, Inc.
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Sync (instead of Connection) required in Connectionless DF
❑Parameters for sync to the periodic advertising channel is obtained
◆in the order of Tx (primary advertising -> secondary advertising -> periodic advertising).
Receiver (Locator)
Transmitter (Tag)
Advertising Set = set of advertising handles
periodic advertiser list -> sync_handle

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Zoom-in of Message Sequence Chart for Periodic Advertising
❑No preference between parameter set-up
❑Actual State of Periodic Advertising depends on the state of Extended Advertising.
❑The periodic advertising data has been defined to be changed at any time.
◆even during the active state of the channel.
Activation sequence
CTE -> Periodic -> AE
* Activated only after AE
De-activation sequence
(not so critical)

13. GCT Semiconductor, Inc.
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Extended Advertising
❑Extended Advertising(AE or EA)
◆= Primary Advertising(Legacy since v4.0) + Secondary Advertising.
◆Long packet, 2 Mbps available only in Secondary Advertising.

14. GCT Semiconductor, Inc.
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HCI of Periodic Advertising
❑Periodic Advertising interval is defined independently.
◆Cannot be periodic all the time in rigor.
✓Priority : primary advertising
❑Channel cannot be controlled(or fixed) by the host.
◆No parameters in the current HCI.

15. GCT Semiconductor, Inc.
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LE Meta (sub-)Events Used in Connectionless DF
❑LE events are mapped into a single Meta Event(0x3E) in Bluetooth Controller.
◆Sub-event code is assigned for a specific LE events.
Sync_Handle used in calling
LE Periodic Advertising Create Sync
LE Meta Events
in Bluetooth Controller

16. GCT Semiconductor, Inc.
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MSC : Connectionless CTE Rx
❑Order of HCI commands in RX side
◆LE Periodic Advertising Create Sync
...
◆LE Set Connectionless IQ Sampling Enable
❑No idea about the number of
◆AUX_SYNC_INDs per AUX_ADV_IND.
✓Figures in spec show to be ‘1’.
✓If 1, very inefficient channel utilization.
p. 3125
I/Q sampling read enable
command is issued after
the sync establishment.
Periodic advertising report
and I/Q sampling report
comes together
+CTE
+CTE
Immediate return
of Create Sync command

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Mux Ratio of ADV_IND/AUX_ADV_IND/AUX_SYNC_IND
❑Aggressive setting of AUX_SYNC_IND interval allows much higher position update rate.
◆Periodic sync internal only duration is mandatory.
7.5ms
~1 sec (= interval of primary advertising) ~1 sec
primary advertising channels
(ADV_IND)
primary advertising channels
(ADV_EXT_IND)
~1 sec
secondary advertising channels
(AUX_ADV_IND)
periodic advertising channels
(AUX_SYNC_IND) w/ CTE
~ Update rate (133 Hz)

18. GCT Semiconductor, Inc.
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CTE Service (CTES) : Tag(Tx) side
❑Generic Attribute Transfer(GATT)-based Profile
◆Description on the characteristics and related behavior.
◆No characteristics for antenna related parameters => Now in IPS-1.1 only
D0.9 in PS D1.0r06 in DFWG SWS
https://specworkspace.bluetooth.com/specifications/s1155/p1372/_layouts/15/DocIdRedir.aspx?ID=BTDOC-1690994450-118

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Examples of Characteristics in CTES
❑No read is allowed(simply security issue ?).
◆The supporting feature is confirmed from the response of write ATT.
Can be used as AoA Constant Tone Extension in advertising packets.
How to check the supporting feature without read ?
How to check the supporting feature without read ?

20. GCT Semiconductor, Inc.
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Asset Tracking Profile (ATP)
❑Characteristics cannot be additionally declared in Profile.
◆Can use multiple set of Services for specific application with extra procedures
https://specworkspace.bluetooth.com/specifications/s1023/p1004/_layouts/15/DocIdRedir.aspx?ID=BTDOC-919711078-168
D1.0r03 in SWS for final review & adoption
D0.9 in PS
Applicable only to
Connectionless DF

21. GCT Semiconductor, Inc.
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[BTI] Test Specifications for Product
❑Generally, not written by the standard developers(including NWP initiator).
◆mechanical/routine job by the contributors from
✓CLOUD2GND(http://cloud2gnd.com/)
✓e-qualus(https://www.e-qualus.com/)
◆Development Cost ?
Test Cases Mapping (Goes to TCRL)

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Qualification (To be implemented in launch studio & PTS later)
❑BQRB - Qualification(+Product Declaration, Branding) Review Board
◆https://www.bluetooth.org/groups/group.aspx?gId=12
◆Launch Studio : fully available to adopter.
✓Re-branding of previous Test Program Generator(TPG)
✓https://launchstudio.bluetooth.com/
◆Profile Test Suite(PTS) program is provided for self qualification.
✓Dongle can be bought at https://store.bluetooth.com/ for $99.
PTS program itself(current v7.5) is free.
✓As the spec goes above v5.x, the PTS dongle H/W gets outdated and cannot support several features.
Advertising Extension, Coded PHY, 2Mbps
Mesh => Interim solution with 2 PTS dongles plugged to the PC for several years.
◆PTS development team joins in the early stage of the IOP
✓Note : Test pass with PTS team does not count in to the score of formal IOP
❑BTI : Test and Interoperability Committee
◆https://www.bluetooth.org/groups/group.aspx?gId=14
◆TS, TCRL, ICS, IXIT
◆In service of TSE : Test Spec Errata (open to any level members)
✓https://www.bluetooth.org/tse/index.cfm
✓Separate system for Main(Core+Profile/Service) standard : https://www.bluetooth.org/errata/index.cfm

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[BTI] Criteria to pass the formal IOP(Standard validation)
❑Basically independent three platforms are required.
◆Pairing of 2 roles => Each role can also pass separately.
✓Each role can be reported independently on the IOP result reporting web forms.
◆In some cases, the pass number is lowered to two.
✓e.g. ATP

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[BTI] IOP Test Plan : Standard Validation Phase
❑IOP Test Plans is prepared after the TS.
◆Also somewhat mechanical & routine job done by CLOUD2GND and e-qualus.
◆Lots of TS part are referenced for brevity.
❑UUID of new CHXs in services should be assigned to a temporary value.
❑Lots of Test cases are excluded in IOP.
◆even after the launching of formal IOP.
12 TCs
17 TCs
[ 1 SVC + 6 CHXs ]

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Assigned numbers not in the spec document any more
❑Assigned numbers in the spec can be accessed on the web after the adoption.
◆Reduces the editorial revision time of the document.
◆Reduces also the probability of conflict.
❑Frequently updated assigned number tables for GATT
◆UUID of GATT services(16-bit)
✓https://www.bluetooth.com/specifications/gatt/services/
◆UUID of GATT characteristics(16-bit)
✓https://www.bluetooth.com/specifications/gatt/characteristics/
◆Declarations, Descriptors are almost fixed.
❑If 16-bit UUID is not assigned,
◆the UUID becomes 128 bit long wasting the air time.
❑Profile-only strategy (recommended) helps to reduce the overall standardization time.
◆The only service, CTES, will be adopted in May and all the UUIDs will be fixed.
◆Least probability of side effect caused by the revision of Core Spec or Services.
◆Neither creation nor revision/improvement of services.
✓Services can be used by other profiles.
✓Lesson from NWP-111.

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Typical examples of locator using connectionless AoA
❑Locator from Quuppa(Spin-off from Nokia)
◆https://quuppa.com/q17/
◆The size of the locator is proportional to the resolution of estimated angle.
✓Mounted on the wall/post vertically.

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CATS for improved Quuppa Trackable Tag
❑Emulation of the tone in the payload part can enhance the quality of positioning.
◆Code in the “Tag Emulation specification(by Quuppa)” reveals no use of tone.
✓https://github.com/narnthan/BLETAG/blob/master/app/src/main/java/tw/com/regalscan/www/bletag/Quup
paTagEmulationDemoActivity.java

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Technology used so far in Quuppa : Non-standard
❑Non-BLE packet is transmitted more frequently in non-BLE channels.
◆BLE compliant tags can be tracked but with a poor quality(accuracy and tracking rate)
tone signal may be used in proprietary channels.

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Tear-down of Fathomsys Locator : ceased operation
❑No conventional AoA using phase difference between the antenna
◆Antenna selection based on RSSI and linear prediction using the RSSI of top two antennas.
✓6 antennas assuming planar mounting (desk or ceiling)
◆100% BLE-4.x compliant using nRF52832(Nordic Semiconductor devices)
6 antenna ports(UFL type)
for patch antenna
main processor for
antenna selection and RSSI combining
UI of the RTLS (no more in service)
4 locators
5 bundle tags + 1 GCT tag
Locator
Tag