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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
< 3 >
• 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
< 4 >
• 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
D2D communication procedure
< 12 >
• 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
< 13 >
• 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
Introduction of flashlinQ (LTE-Direct)
< 16 >
• A new peer-to-peer communication technology developed by Qualcomm
• Licensed spectrum
• Without infrastructure support
• Synchronous discovery
• OFDMA modulation
FlashlinQ
< 17 >
• 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
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>
< 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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