This document provides biographical information about Hayoung Yoon and summarizes her educational and professional experiences. It describes her background in wireless networking research and her work developing solutions for Wi-Fi Direct and mobile video-on-demand applications. It also outlines her experience founding zVolti to develop automated testing solutions for wireless connectivity products.

1. A Short Story…
Trial and Error
!
2017.12.28
!
Ph.D. Hayoung Yoon
!
hyyoon@zvolti.com

2. Trial and error is a fundamental method of
problem solving. It is characterised by
repeated, varied attempts which are continued
until success, or until the agent stops trying.
*from Wikipedia

3. About Me
Experience
3
HayoungYoon (윤하영)
zVolti
Co-Founder & R&D Lead (2013~)
WiFi/BT Test Automation
ITEC-Tokyo (Tokyo, Japan)
Manager (2012~2013)
WiFi P2P Data Sharing Solution
I2R (Institute for Infocomm Research)
(Singapore)
Intern (2010)
Peer-based Multimedia Distribution System
National ICT Australia (Sydney,Australia)
Intern (2009)
Mobility Emulation for Wireless P2P App. Experiments
Deutsche Telekom T-Labs (Berlin, Germany)
Intern (2006)
P2P Service Framework over WiFi network
Education
Gwangju Institute of
Science and Technology (GIST)
Ph. D., Information & Communications (2011)
Master, Information & Communications (2006)
Korean Aerospace University
Bachelor, Telecom. & Info. Engineering (2004)
COMPANY
zVolti
Seoul, Korea
Saratoga, CA
Founded
Feb, 2013
Product & Service
ZESTER
Wi-Fi/BT Test Automation Solution
Wi-Fi/BT Product QA Consulting
Partners
Samsung Mobile Comm.
Broadcom Wireless Connectivity
Qualcomm Wireless Technology
Samsung System LSI
SKT
KT

4. Timeline After Graduate
Professional
4
Personal
Meet my boy
First Job
First
Startup
Academy Industry
A Man Father and Husband
Meet my daughter
First
Contract
(Korea)
Start Master Start Ph.D
Intern #1
Intern #2
Intern #3
Meet Prof. Ko
First Research
Paper
First
Contract
(Overseas)
Meet my wife
Meet zVolti CEOMeet Dr. Robert
Meet Prof. Kim
Tech Transfer to ITEC-Tokyo

5. Why? Graduate School?
5
Started “student intern” in the Next-generation Networking
Lab (Prof. Sungchang Lee). in my 3rd year of undergraduate
program, where I meet NS-2 (Network Simulator) and wireless
ad-hoc network.
For me, playing around with NS-2, especially running MANET
simulation, was as fun as playing a Starcraft!
And we call it “Destiny”

6. Deutsche Telekom T-LAB Internship
6
Overcoming “Language” Barrier
• I’ve taught in English during Master programs, however…
• It was so hard to convince my Boss (Dr. Robert), although he was
very patient listener, the validity of my S/W design (NS-2) in
English
• I’ve found out that
• the language we spoken are different
• the way we deliver idea is far different
I’ve googled his previous research paper and found one paper
including the description of his NS-2 codes

7. Initial Attempt
NORT
(nort/nort.cc)
MAC
(mac/opan/mac-
802_11_opan.cc)
LL
(mac/ll.cc)
PHY
(mac/wireless-phy.cc)
Channel
(mac/channel.cc)
OPAC_STA
(app/opan_sta.cc)
IBDS
(ibds/ibds.cc)
MAC
(mac/opan/mac-
802_11_opan.cc)
LL
(mac/ll.cc)
PHY
(mac/wireless-phy.cc)
Channel
(mac/channel.cc)
OPAC_CCS
(app/opan_ccs.cc)
Other’s code
AGT_UDP
(app/udp.cc)
AGT_UDP
(app/udp.cc)
Newly Written
NS-internal
Access pointMobile node
< OPAN system blocks >
Station sends opan_request (Implicit, NoP2P)
Timeout
Check receive all chunks NO
YES
Station sends opan_report UDP recv
UDP send
LL recv
LL sendDown
ARP check
LL fills MAC header (mac::hdr_dst)
IFQ recv
MAC recv
P2P_Timeout
Check send all
p2p chunks
YES
STA_END
Station sends “opan_p2pd”
NO
< Mobile node Operations: from APP to MAC >

8. LL
MAC
PHY 1
CHANNEL 1
PHY 2
CHANNEL 2
PHY
Select Table
ARP
Inter BSS
Distribution
System
Agent
Src/Sink
Radio
Propagation
Model
IFQ
AC
VO
AC
VI
AC
BE
AC
BK
addr
demux
port
demux
Node
entry_
defaulttarget_
255
uptarget_
target_
downtarget_
uptarget_downtarget_
AP
Association Table
Dest: AP_X
Port: 254
---------------
Dest : N_X
Port: 1
Dest : N_X
Port: 1
Dest : N_X
Port: 1
N_X
N_V
NET_A
Dest : N_X
Port: 1
Dest : N_Z
Port: 100
Dest: AP_X
Port: 254
---------------
Dest : N_X
Port: 1
IF N_X is no more associated,
just free packet and update
switching table
Dest : N_Z
Port: 100
Dest : N_Z
Port: 100
Dest : N_Z
Port: 100
Dest: AP_Z
Port: 254
---------------
Dest : N_Z
Port: 100
Dest: AP_Z
Port: 254
---------------
Dest : N_Z
Port: 100
Dest: AP_Z
Port: 254
---------------
Dest : N_Z
Port: 100
UP-link Down-link
< OPAN Access Point Schematic >
uch
of
off
on,
the
nce
as
ese
ast-
ns
‘ns
v4)
our
t a
our
ent
nly
In
bile
his
ort
the
ion
rity
was
Figure 4. Schematic of Mobile Node
Figure 3. Schematic of a MAP Node
ch
of
ff
n,
he
ce
as
se
t-
ns
ns
4)
ur
a
ur
nt
ly
In
le
is
rt
he
on
ty
Figure 4. Schematic of Mobile Node
Figure 3. Schematic of a MAP Node
A Trial
Pics from my Boss’s previous paper How I adopted to explain my work

9. An Error
9
All my machines gone and all my work gone, too
• I worked 7 days full-time to finish earlier to travel Europe in the
last 2 weeks (It was a deal with my Boss!)
• It was 2006, the world-cup season, the level of public safety was
quite low even in the capital, Berlin
• One day, passing around 2/3 of the internship, I came to work and
found there was robberies in the lab and all my machines, including
backup disk had disappeared.
• I was the last person, as far as I can tell, in the night before. So I
have to explain to the German policeman about the night and I am
not the guy.

10. A Trial
10
Cancel all travel booked and rewrite every code
• I’ve reported to my boss regularly, so he knew the work is almost done
• It is very important to report your boss that you are working and useful asset!
• The project was two parts in the first pace:
• Write simulation code and paper work
• Implement code running in Linux for PoC (proof of concept)
• We (me and boss) decided to skip the implementation part and focused on
recovery of simulation codes
• I was afraid for not delivering what we planned, so push forward to
implement some of essential codes can be ran in Linux
• And this becomes the “key” we got a fund from D-TLABs for the future project
for two years

11. An Error
11
After the internship I though I could finish my Ph.D
quickly but…
• The research went to implementation-oriented, so it was very hard
to be published
• At some point, I hated paper work and focussed on system
implementation
• I’ve ended up being rejected so many journal papers submitted.

12. Peer-assistedVoD
DR DR
PR PR
DR > PR DNR + DSR > PR
DSR
PR PR
DSR
Server
Client Client
Conventional VoD
Server
Client Client
MOVi
1. Better Channel Quality
!
2. Lower Power Consumption
!
3. Higher data-rate
1. System capacity increased
!
2. Server load deceased
DNR
start
playout
pre-bufferingT
pause
playout
pauseT
re-start
playout
Req
Network
Video player
<Video on-demand>

13. Mobile OpportunisticVideo-on-demand
MOVi Server
802.11
Mobile Networks
Probing
(Passive or Active)
Local Contents
Cache
Neighbor
Connectivity
Contents
Distribution
P2P Link
Scheduling
Segment
Download
Schedule
XàY
Seg: A
DS: Distributed System
802.11 DS
MDC

14. A Trial
14
Some of Startup company got interested in my work
• One day, 2011, I was planning to prepare 3rd internship for integration of
MOVi with 3G cellular networks and network codings, I got a call from
GIST
• One of the Japanese startup company wants to buy our IPs
• I traveled to Seoul, US, Japan many times to do MOVi demos and
convince them the technology is realisable

15. Recall 2011…
• Multiple Wireless Connectivity on Mobiles
• Not So Simple Applications
3G 2G Edge
Bluetooth
FM
!
GPS

16. A Trial
16
Meet many Wi-Fi Chipset Vendors for integration of MOVi
• Many mobile handset makers like Samsung, LG, Nokia, Sony… were not
really prepared for what iPhone brought
• The easiest way for them to sell is that the technological advances
• “Our phone” is the world first phone supports 802.11n Wi-Fi
• “Our phone”’s downloading speed is higher than 100Mbps
!
• They can be something distinguishable, but do people really want them?

17. An Error
17
We’ve integrated solutions to TI/Broadcom Wi-Fi chipsets but…
• We’ve encountered so many problems in Wi-Fi itself under the user scenarios
• We’ve faced so many side-issues for conflicts between vendor specific Wi-Fi’s
features and MOVi
• We’ve found so many Wi-Fi inter-operability issue across different vendors (WHY?,
What happened to the standard specifications?)
• Failed to make our solution being ever-spread
WiFi Device Driver
Native
Android Framework
Android APP
Android Framework
Vendor-A specific DR/FW
Vendor-A specific Daemon
3rd party Application
+ɑ
+ɑ
Vendor-B specific DR/FW
Vendor-B specific Daemon
+b
+b

18. WFD is a Multi-player Game
• AP (or GPU)Vendors
• Better performing AV processor
• WiFi ChipsetVendors
• Fast/Reliable/Energy-efficient WiFi
• Manufacturers
• Optimal deployment of
communication and AV processing
units
• Smooth UX designs
• WFD Solution Provider
• Cross-platform/Cross-chipset vendor
WFD Architecture and Requirements
3-1 illustrates the functional blocks in the Wi-Fi Display data and control planes. The data plane
s of video codec (section 3.4.2 and 3.4.4), audio codec (section 3.4.1), PES packetization (Annex-B),
CP system 2.0/2.1 (section 4.7), and MPEG2-TS over RTP/UDP/IP (section 4.10.2 and Annex-B).
ntrol plane consists of RTSP over TCP/IP (section 6), remote I2C Read/Write (section 7), UIBC
IDC and generic user input (section 4.11), and the HDCP session key establishment (section 4.7).
-Fi P2P/TDLS block forms the layer-2 connectivity using either Wi-Fi P2P or TDLS as described in
4.5.
TCP
Control
(RTSP)
CapabilityNegotiation,SessionEstablishment,
MaintenannceandManagement
L2SetupandDiscoveryAssist
RTP
UDP
IP
Wi-Fi P2P / TDLS and Wi-Fi Protected Setup
UIBC
Capsulation
UserInputData
Generic
HIDC
HDCP2.0ControlMessage
MPEG2-TS
PES
packetization
Audio
codec
Video
codec
HDCP 2.0 / 2.1
Remote
I2C
R/W
I2CData
Figure 3-1 : Logical Data and Control Plane Connections
WFD Source, Primary Sink, Secondary Sink and WFD18

19. A Trial
19
There is no chances for small company in the solution business
• The development cycle is crazily fast
• So many vertical integrations happening therefore company needs many
corresponding experts
• I Know Wi-Fi, Linux/OS, and understand various applications, why don’t I make a
company do tests
2Q/2011
DS
DLS
• Not to loose packets from AP
• We propose and implement miDLS
support two mobile WiFi devices migrate
to other channel for short time and
comeback
• No additional H/W support by both the
network interface card (NIC) and the AP
• Average switching duration in MadWiFi-
based implementation < 20ms
CHA
802.11b
802.11g
WiFi
Bluetooth
with miDLS
• W
su
to
co
• N
ne
• A
ba
CHA CHA
CHB
802.11b
802.11a802.11g
802.11e
802.11n
WiFi Direct
WiFi
Miracast
WiFi TDLS
802.11k/r
802.11u
1Q/2017
Concurrency
802.11ac
Multi-User MIMO
Beam-forming
2x2 MIMO
Bluetooth
5.0
Bluetooth
Low
Bluetooth
SINK
ANT/ANT+
MPTCP
Dual A2DP

20. FOCUS HERE!
Modern Handset Development
The QA verified on Vendors’ Sample or Development Board
is never valid in their customers’ final product
Latest OS: N, O & P…
Carrier-specific
Spec & Features
Agile R&D
Pressure
Solution/
Chipset
- VoWiFi
- MPTCP
- Location-based SVC

21. Typical Wi-Fi/Bluetooth Scenario
WI-Fi
Connection
ANT+
Simulation
BLE HOGP
BT HID
ANT Connection
BT HFP Headset x 2
On-demand
Actions
-Wi-Fi Scan
-Reconnections
-Roaming
-BT/BLE Scan
-Pairing-REQ
-ANT Scan
-Data RX/TX
Operations
in Background

22. Test Requirements
Pan&Tilt Setting
1
1. Connect DUT to ZESTER
- USB Micro B
2. Connect PanTilt Control Box to ZESTER
- USB type B
ZETSER
PanTilt
Control Box
2
DUT
• On the “off-the-shelf” devices
• Extensible
• Dev Assist
➡ Extensive System logs
➡ Benchmark
➡ Air-Logs
➡ System-level view and statistics
➡ User-binary tests
➡ Plug & Play
➡ Interoperability
➡ Test a case incorporate with existing H/W
➡ Export result to well-known formats
➡ Test controls from 3rd party
• Automation
➡ 7x24 overnight test
➡ Progress/Final Report
➡ Notification (Email or Push MSG)
➡ DUT failure recovery

23. Conventional Approach
User Scenario
in Real Environments
Interoperability
(spec, non-spec)
RF/Protocol
/App. specific
RequiredVolume
ofTestcases
Component
Driven Test
➡ Hard to test “off-the-shelf” devices
➡ Not so expendable
➡ Almost impossible to test in real user env.
➡ Expensive to make it running in parallel

24. API-Driven Test? Why?
Linux Kernel (DR/FW)
!
!
Native
!
Android
Framework
Android APP
Android APIs
Calling APIs
Custom C/C++ Code
JNI
Calling
Custom
C/C++ Code
IOCTLs
Reflection
H/W Chipset / RF
Data
I/O
• Test at User Level
• Test vertically
• Test before UI Fixed
• Test without application failure
• Test a common scenario for
different OEMs, Wi-Fi/BT
Chipsets, Different Platform
Versions
WHY?

25. The Challenges
25
I’d like to make a company, where the engineers
• can do engineering work (hopefully until 60)
• adjust quickly to technological changes (learning)
• can really contribute to the product
• make a product that the customers dying for it

26. Wanted
26
We need a “T” guy
• Has broad knowledge for general communications and collaborations
• Vertical (Back-end Service and LTE H/W Engineer)
• Has speciality to interact with other experts
• Horizontal (For better design choice)
Whom can further be a “∏” guy
• Keep learning new technology
• New area or field (S/W engineer could learn H/W)
• Being a “Maker”
• Can design and build own product
• Make your own startup

27. Recommended (1)
27
Go to Graduate School if you wish
• Enjoy the freedom of failure
• Learn broad aspect of ICT
• Being social with people in the other Labs and learn
there idea
• Being useful in the Lab
• Build your own speciality and teach it to other mates
If you have an idea
• Just make it realise even if it is yet concrete
• No great idea came with completeness
• It is even better if it is based-on open source project
• If you curious about how the TCP works, go and read codes to revise

28. Recommended (2)
28
Keep yourself and your boss updated
• It is good habit to plan your work and record
progress
• Helps you to do always more work (good, right?)
• Could be used for an excuse in accidents
Have your own elevator speech (short!)
• What is your background
• What are you good at
• Why and how do you work on your current project
• What are you looking for
I studied mobile wireless communication technologies, especially wireless LAN
and data diffusions, in my Ph.D and have co-found and been running a start-up
for 5 year so far which provides Wi-Fi/BT chipset vendors and mobile hadset
manufactures an autonomous test and QA solution. We are partnering with
market leading Wi-Fi/BT chipset vendor and handset maker in the world. We’d
like to hire competitive employees to explore our venture together.

29. Questions?
Thank You

30. Wi-Fi/LTE Multipath Aggregation (1)
Wi-Fi LTE
30
• Better throughput
• Seamless connection
• Lower price for communication
BD…
AC…
ABCD…
+

31. Wi-Fi/LTE Multipath Aggregation (2)
31
• Application Driven
• MPTCP (Multipath TCP)
• RAN (RADIO Access Network)
Aggregation
Normal WebserverMultipath-aware HTTP
MPTCP-patched WebserverNormal App using TCP
Normal App
Normal Webserver
No H/W Infra change
No H/W Infra change
HUGE H/W Infra change
S/W patch for web server
iOS Siri!
Samsung download booster

32. Wi-Fi/LTE Multipath Aggregation (3)
32
$$$$$
Normal WebserverMultipath-aware HTTP
MPTCP-patched WebserverNormal App using TCP
Normal App
Normal Webserver
No H/W Infra change
No H/W Infra change
HUGE H/W Infra change
S/W patch for web server
Support Any Applications
$
Application Specific
$($$ with Proxy)
Covers every TCP
applications