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D2D Communication: Technology and Prospect

Sunghyun Choi, Ph.D., Professor

Multimedia & Wireless Networking Lab.

Dept. of Elec. & Comp. Eng.

Seoul National University

< 1 > * Special thanks to Jongwoo Hong

Contents

< 2 >

• Introduction

• D2D usage scenarios

• D2D communication procedure

• D2D communication technology

FlashlinQ (LTE-Direct)

3GPP Proximity Services

• Related papers

• Conclusion

Introduction

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• What is D2D (Device-to-Device) communication?

D2D communication allows device to communicate directly each other over the

D2D links without infrastructure

Different from M2M, D2D is supposed to be an access or link-layer technology.

Emerging license band-based D2D devices are expected to share the same

resources with cellular system

eNode

Cellula

r Lin

k

D2D Link

UE UE

UE

UE

Cellular Link

Cellular Network

D2D Network

Advantages of D2D

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• Reduced device transmission power

• Reduced communication delay

Device can communicate with neighbor device

• Cellular traffic offload

Enhanced cellular capacity

Better load balancing

• Increased spectral efficiency

Spatial reuse through many D2D links

• Extended cell coverage area

• Easy support of location based service

Different D2D usage cases

< 5 >

<Lei Lei, Zhangdui Zhong, Chuang Lin and Xuemin (Sherman) Shen, ”Operator Controlled Device-to-Device Communication in

LTE-Advanced Networks,” IEEE Wireless Communications, June 2012>

Local voice service Local data service

UE as a gateway to sensor networks UE cooperative relay

D2D scenarios

< 6 >

<M.scott corson, Rajiv Laroia, Junyi Li, Vincent Park, Tom Richardson and George Tsirtsis,” Toward proximity-aware

interworking ,” IEEE Wireless Communications, December 2012>

D2D scenarios

< 7 >

<LTE Direct Overview, Sajith Balraj, Qualcomm Research, 2012>

• Devices advertise their services

D2D scenarios

< 8 >

<Mi Jeong Yang, Soon Yong Lim, Hyeong Jun Park, and Nam Hoon Park, Solving the Data Overload, Device-to-Device

Bearer Control Architecture for Cellular Data Offloading, IEEE vehicular technology magazine, March 2013 >

• Data offloading

Trends in D2D standardization

< 9 >

• Licensed band

FlashLinQ (LTE-Direct) by Qualcomm

3GPP LTE ProSe (Proximity Service)

IEEE 802.16 PPC (Project Planning Committee)

Two different types of D2D

• Without network assist

< 10 >

• With network assist

eNodeB

UE

D2D Link

UE

D2D Link

UE UE

eNodeB

< 11 >

D2D communication procedure

D2D communication procedure

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• Device discovery

Detecting the presence of other devices in the neighborhood

• Link setup

Establishing links between interested devices

• Data communication

Transmitting or receiving data via established links

D2D communication procedure

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• D2D communication procedure

Network assistance from eNodeB is optional

2. Link setup

UE 1

eNodeB

UE 2 UE 3

Device discovery

Link setup

1. Device

discovery

3. Data communication

Data commmunication

Network assisted

information

Network assisted information (optional)

Different peer discovery techniques

< 14 >

posteriori case – a token

<G. Fodor, E. Dahlman, G. Mildh, S. Parkvall, N. Reider, G. Miklos, and Z. Turanyi, Ericsson Research, “Design

aspects of network assisted device-to-device communications,” IEEE Communications Magazine, March 2012>

A priori case – broadcasting

A priori case – registration posteriori case – IP address analysis

< 15 >

FlahslinQ (LTE-Direct)

Introduction of flashlinQ (LTE-Direct)

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• A new peer-to-peer communication technology developed by Qualcomm

• Licensed spectrum

• Without infrastructure support

• Synchronous discovery

• OFDMA modulation

FlashlinQ

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• Peer discovery

Devices (application) discover all other devices within range (up to ~ mile)

Capable of discovering thousands of devices

Identify only authorized devices (privacy maintained)

Automatic power efficient discovery without human intervention

• Paging – initiating communication

Link established through paging

• Communication

Once link established, devices can securely communicate

All pairs that can coexist communicate simultaneously

FlashlinQ

< 18 >

• Synchronous discovery

Periodically, every device transmits its peer discovery signal and also listens to peer

discovery signals of others to detect devices of interest in the proximity

Peer discovery occupies roughly 20 msec every one second

• PHY signaling: single-tone OFDM signaling

To increase range and be able to discover many at a time

Discover devices to communicate and potential interferers

Peer Discovery

Resource

20 ms 20 ms

1second

Peer Discovery

Resource

FlashlinQ

< 19 >

• FlashlinQ resource

20 msec

...56 (5 MHz)

8

70 OFDM symbols on a single tone

(PDRID)

8 sec (1 Discovery Repetition)1 sec

Control Discovery Traffic ... Control Discovery Traffic

89 KHz

2.5 msec

• PHY signaling: single-tone OFDM signaling

FlashlinQ: discovery

< 20 >

• Discovery solution

1 discovery repetition (512 sec)

NF

0

55

1...

...

1 Peer discovery repetition

(8 sec)

0 1 63... ...

...

t=0 t=1 T=63 (NT-1)

1 Peer discovery repetition

(8 sec)

Miss other transmissions when transmitting due to half-duplexing

May not be able to hear all simultaneous transmissions due to desensing

Solution for above issues is hopping (Latin square pattern)

PDRID (Peer Discovery Resource ID) hops in time and frequency pseudo-

randomly due to half-duplexing and desensing

This above figure does not include frequency hopping for simplicity

FlashlinQ: communication

< 21 >

• SINR based yielding (similar to RTS/CTS)

Tx-yielding: yield if the SINR (interference from the transmitter) of a

higher priority connection is below a certain threshold

Rx-yielding: yield if its own SINR is below a certain threshold

Rate scheduling: using estimated SIR, the code rate and modulation is decided

< 22 >

3GPP Proximity Services

3GPP Proximity Services

< 23 >

• Proximity Services (ProSe) study in 3GPP Release 12 & Onward

• Scope

Commercial/social use

Network offloading

Integration of current infrastructure services, to assure the consistency

of the user experience including reachability and mobility aspects

Public safety, even in case of absence of EUTRAN coverage

• The objective is to study use cases and identify potential requirements for

operator network controlled discovery and communications between UEs

<3GPP TR 22.803 Feasibility study for Proximity Services (ProSe) v12.00 2012-12>

Proximity Services discovery

< 24 >

• ProSe Direct discovery

A procedure employed by a ProSe-enabled UE to discover other

ProSe-enabled UEs in its vicinity

• EPC-level ProSe discovery

A process by which the EPC determines the proximity of two ProSe-

enabled UEs and informs them of their proximity.

3GPP Proximity Services

< 25 >

• Data paths for ProSe Communications

<3GPP TR 22.803 Feasibility study for Proximity Services (ProSe) v12.00 2012-12>

UE

1

UE

2

eNB

eNB

SGW/PGW

• Default data path setup in the EPS

for communication between two UEs

UE

1

UE

2

eNB

eNB

SGW/PGW

• The “direct mode” data path in the EPS for

communication between two UEs

• Default data path scenario • ProSe Communication scenario

3GPP Proximity Services

< 26 >

• Control paths for ProSe Communications

• Control path for network supported ProSe

served by the same eNB. (solid arrows)

• Control path for network supported ProSe

served by different eNBs

UE2

eNB EPC

UE1

UE2

UE1 eNB

EPC

eNB

• ProSe Communication are served by the same eNB and different eNBs (e.g., macro/micro cell)

• Control information exchanged between the UE, eNB and the EPC

(e.g., session management, authorization, security)

<3GPP TR 22.803 Feasibility study for Proximity Services (ProSe) v12.00 2012-12>

< 27 >

Related Papers

< 28 >

• Interference avoidance mechanism

<T. Peng, Q. Lu, H. Wang, S. Xu, and W. Wang, “Interference avoidance mechanism in the hybrid cellular and device-to-device systems,” in Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Sept. 2009.>

Related papers - Interference

Related papers – Time hopping

< 29 >

• Resource allocation with Time Hopping

• Randomize and minimize the overall channel collisions

<T. Chen, G. Charbit, and S. Hakola, “Time hopping for device-to-device communication in LTE cellular system,” in Proc. IEEE Wireless Communications and Networking Conference, (WCNC), Apr. 2010.>

Related papers – Resource allocation

< 30 >

• Possible resource allocation modes

<C.-H. Yu, O. Tirkkonen, K. Doppler, and C. B. Ribeiro, “Power optimization of device-to-device communication underlaying cellular communication,” in Proc. IEEE International Conference on Communications (ICC) , Apr. 2009.>

Related papers – Power control

< 31 >

• Dynamic power control scheme for D2D pairs

<Jaheon Gu, Sueng Jae Bae, Bum-Gon Choi, Min Young Chung, “Dynamic power control mechanism for interference coordination of device-to-device communication in cellular networks," Ubiquitous and Future Networks (ICUFN), Jun, 2011>

eNode

D2D Link

Cellular UE D2D UED2D UE eNode

D2D Link

Cellular UED2D UED2D UE

Tx power control

Dynamic Power Control

Conclusion

• D2D is an emerging wireless technology for direct communications among

devices

• D2D is expected to be a key technology to improve system capacity and

user experience in various service scenarios.

• There are many technical issues including how to coexist with cellular

network users and how to deal with interferences

• We also need to develop D2D applications which are attractive to both

operators and users

< 32 >

[1] M.scott corson, Rajiv Laroia, Junyi Li, Vincent Park, Tom Richardson and George Tsirtsis,” Toward proximity-

aware interworking ,” IEEE Wireless Communications, December 2012.

[2] G. Fodor, E. Dahlman, G. Mildh, S. Parkvall, N. Reider, G. Miklos, and Z. Turanyi, Ericsson Research

“Design aspects of network assisted device-to-device communications,” IEEE Communications Magazine, March 2012.

[3] Lei Lei, Zhangdui Zhong, Chuang Lin and Xuemin (Sherman) Shen, ”Operator controlled Device-to-Device

communication in LTE-Advanced networks,” IEEE Wireless Communications, June 2012.

[4] Xinzhou Wu, “FlashLinQ: A clean slate design for ad hoc networks,”ppt slides.

[5] Francois Baccelli, Nilesh Khude, Rajiv Laroia, Junyi Li, Tom Richardson, Sanjay Shakkottai,

Saurabh Tavildar, Xinzhou Wu, “On the design of Device-to-Device autonomous discovery,” COMSNETS, 2012.

[6] Xinzhou Wu, Saurabh Tavildar, Sanjay Shakkottai, Tom Richardson, Junyi Li, Rajiv Laroia

Aleksandar Jovicic, “FlashLinQ: A synchronous distributed scheduler for Peer-to-Peer ad hoc networks,” Forty-Eighth

Annual Allerton Conference, 2010.

[7] 3GPP TR 22.803 Feasibility study for Proximity Services (ProSe) v12.00 2012-12.

[8] 김현숙, D2D 서비스 지원을 위한 3GPP 네트워크 구조 및 표준 기술 동향, LG전자.

[9] 성선익, 홍종우, 김경수, 박승일, 박천우, 최성현, 이광복, “셀룰러 네트워크 기반의 D2D 통신 기술 현황,”정보와 통신,

2012년 7월.

[10] 홍종우, 성선익, 박승일, 박천우, 김준영, 최성현, 이광복, "D2D 통신 기술 및 표준화 동향,”전자공학회지, 2013년 4월.

References

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Thank you

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