Post on 09-Jun-2018
Copyright © 2013 DOCOMO Communications Laboratories Europe GmbH IRG
D2D – Time has Come for Proximity-based Applications
Dr. Matthias Lott, Dr. Dirk Staehle, Dr. Katsutoshi Kusume, Dr. Liang Hu
DOCOMO Euro-Labs, Germany
ITG 5.2 Zukunft der Netze – Application-Driven Networks
Osnabrück, September 20, 2013
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• What is D2D?
• Why Time has Come?
• Architecture
&
Solutions
• Definition (3GPP)
• Use Cases
• Description
• Difference to M2M
• Business Impacts
• Trends & Drivers
• D2D in the Future Architecture
– Phantom Cell
• Challenges
• Solutions
• Summary
Content
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Device-to-Device (D2D)
Proximity Service (ProSe) / D2D def. of 3GPP TR 21.905 / TR 22.803:
• Discovery / Proximity Service (ProSe)
– a process that identifies that a UE is in proximity of another, using E-UTRA or EPC
• ProSe (Direct/D2D) Communication
– a communication between two UEs in proximity
– the communication path could be established directly between the UEs or routed via local eNB(s)
Definition (3GPP)
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• Two main groups of use cases: 1. Commercial 2. Public Safety
Use Cases Classification - Examples
Commercial
Discovery of partner
Diff. operators
Roaming users
Discovery for D2D
communication
Enhance Location / Presence info
ProSe API to 3rd party app. developer
Handover support
ProSe for M2M
Offloading (WLAN, disaster)
Public Safety
ProSe Group / (local) Broadcast
Relay / Range extension
Implicit discovery
Discovery within / outside
NW coverage
WLAN support
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Offloading
NSPS
Traffic Safety
Automation
Proximity-enabled communication between a group of terminals
Fast data transfer between devices
Advertisements to terminals for by-passers
Diversity in terms of use cases, requirements, terminal capabilities,...
Proximity based social networking, gaming
Use Cases Diverse service requirement - examples
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Description Topology Scenarios & Use Cases
Control signals Data
Localized data service
• M2M (V2V)
• Content sharing
• Multi-user gaming
• Mobile advertising
• Local voice service
Pure D2D architecture D2D Multicast Archit.
Localized data service
• Content sharing
• Multi-user gaming
• Mobile advertising
D2D Relaying Archit.
Localized data service
Relaying
• Relay-functionality
• Sensor networks: UE as gateway to sensors
+ Intra/inter-cell D2D
I.
II.
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Description RAN support & Frequency Bands
Network controlled (RAN support) UE controlled (No RAN support)
Lice
nse
d b
and
U
nlic
ense
d b
and
UE UE
Data
Control signals
Ad-hoc mode
UE UE
Data
Control signals
Disaster case
eNB
Control signals
UE
UE
Data
“Cellular assistance” (min. support)
Control signals
UE UE
Data
“Typical D2D”
eNB
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Description D2D Discovery & Communication
with NW coverage w/o NW coverage
D2
D d
isco
very
D
2D
co
mm
un
icat
ion
eNB
Control signals
UE UE
Discovery signal
Required both for commercial and public safety
UE
UE
Discovery signal
Public safety only
UE
UE
Data
Control signals
Public safety only Required at least for
public safety
eNB
Control signals
UE
UE
Data
I.
II.
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• Relationship between Discovery & Communication
Description D2D Discovery & Communication
D2D Discovery / Proximity Service
Communication (via eNB)
D2D Communication (direct link)1)
Step1: Discovery
Step2: Data
exchange
Service Update3) (client-server)
• 1) Including LTE direct-link and direct connection via different RAT, e.g. WiFi • 2) Public Safety Implicit Discovery (D2D communication w/o explicit ProSe Discovery event) • 3) D2D discovery resp. proximity information could be utilized for applications, too (e.g. as friend-finder, nearest
printer or in general device / M2M, targeted advertisement, etc.)
Implicit Discovery2)
Benefits for user, operator & service provider due to new information & communication service
D2D Communication between devices
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• M2M (Machine to Machine) / MTC (Machine Type Com.) (3GPP TR 22.368)
Definition: M2M/MT Communication is a form of data communication between entities that do not necessarily need human interaction.
Difference to M2M
D2D M2M
Describes connectivity service
Defines a class of devices & is application oriented
Main target Discovery and local communication
Data exchange between machines / infrastructure
Type of device Not defined (arbitrary) Machine
Number of devices Typically two or a few Typically many
Location Proximity Not defined (arbitrary)
Communication Between devices (D2D) Typically many to one (N terminals to 1 server; machine to infrastructure)
Application
Connectivity Service
M2M
D2D
Resources
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Business Impacts of D2D Discovery
eNB
Internet
Data
UE
eNB-D2D
Internet
Data
UE
D2D Data
D2D Data (logical path)
D2D Discovery
D2D Discovery creates new proximal end-to-end communication pairs opens new service opportunities and creates new end-to-end traffic
Operator KPI: Unified & easy AAA/charging
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Business Impacts of D2D Communication
eNB-D2D
Internet
Data
D2D Data
D2D Data (logical path)
D2D Communication
eNB-D2D
Internet
Data
D2D Data
Benefits: - Higher throughput - Shorter delay - Higher spectral
efficiency - Traffic offloading - etc.
D2D Communication can efficiently handle new large amount of end-to-end traffic enabled by D2D Discovery
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• QoS: Guarantee of QoS (assignment of dedicated spectrum / resources)
– Low latency, high bandwidth,
• Reliability: Stable Proximity Service (discovery and communication)
– Carrier-grade infrastructure & network elements
– Different communication paths (diversity) availability / coverage
• Mobility management / handover support (infrastructure / D2D mode)
• Security: Apply security schemes known from cellular system
• Legacy voice service: Conventional numbering scheme & QoE
– No pairing like used for BT, WiFi, …
• Energy consumption: Support of power management
• Provisioning & scalability: Availability of infrastructure for management of high number of devices
• …
Business Impacts Competitive Advantages of Mobile Network Operators
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Trends & Drivers
Technical Trends
Social / Economic
TDD for 5G
TDD for D2D communication
D2D as “connectivity mode” for M2M
D2D for energy saving (Green IT)
Public safety and commercial service are developed jointly
Standardization of ProSe in RAN1 and SA1
D2D increases resource efficiency
Social communities and sharing within small groups
D2D enabled UE for wireless backhaul
Public safety supports discovery AND communication
Standard-ization
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D2D in the Future Architecture - C/U Plane Split & Phantom Cell
• Hybrid usage of lower & higher frequency bands (e.g. 2 GHz & 3.5 GHz)
• Proposed macro-assisted small cell – “Phantom cell”
– Split of C-plane and U-plane between macro & small cells in different bands
– Phantom cells likely to be dynamic TDD as it is the case for D2D
– Link between UE and Phantom cell is similar to D2D link
Macro cell
Macro cell network
Small cell network
U-plane
2 GHz (Example) No coverage
issue anymore
3.5 GHz (Example) High throughput
Big offloading gain
Phantom cell D2D
D2D
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Challenges for efficient D2D Discovery
• Half-duplex scheme (TDD)
– Discovery signals might collide
– UE cannot listen to others while it is transmitting
Challenges for D2D Communication • if UE controlled: Collisions problem, critical for latency-sensitive D2D service & local sub-
optimal due to the lack of NW support • If NW controlled: spatial re-use not possible (e.g. w/o GPS info.); high RRC signaling
overhead; not applicable out of NW coverage
• D2D between devices subscribed to different operators
– Which spectrum to use (for direct communication)?
• Lawful interception
– How to monitor direct communication?
• Charging
– How to perform (content-based) charging?
– How to charge if D2D communication is supported w/o NW coverage?
• Privacy, Security, Authentication, Out-of-the-box operation (for public safety), … etc.
Challenges
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Solutions Efficient Transmission of Discovery Signals
Approach: (1) Introduce resource group (RG) patterns, (2) allocate UEs to a RG, (3) let each UE arbitrarily select one discovery resource (DR) within the allocated RG
f
t
RG4
RG3
RG2
RG1
RG8
RG7
RG6
RG5
RG12
RG11
RG10
RG9
RG16
RG15
RG14
RG13
f
t
RG1
f
t
UE2
UE1
UE3
UE4
UE5
UE1 UE1
UE2
UE3
UE4
UE5
UE2
UE3
UE4
UE5
Fully centralized Fully distributed Partially centralized collision possible
Each UE deterministically select allocated DR
Each UE arbitrarily select 1 DR out of 16 DRs in RG4
collision free
Definition •RG pattern is a set of RGs •RG is a set of DRs or only one DR
RG1 RG2 UE1
UE2
UE3
UE4
UE5
f
t
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3
2
1
6
5
4
9
8
7
Residential building
Office Building
UE Group A UE Group B
Radio Resource
From radio propagation point of view, UE group A and B have good spatial separation The entire radio resource can be used by Group A and B simultaneously. Further improve the spectrum efficiency of D2D discovery New signaling and procedures are needed for
Smart Discovery Resource Allocation that enables spatial resource re-use
Context-Aware Discovery Resource Allocation
Solutions Efficient Discovery considering location information
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• Proximity Services / D2D offer plenty of potential use cases and business opportunities
• Many drivers exist for D2D
– With increasing importance of TDD the basic communication mode will be provided as part of the next generation network
– With the introduction of D2D for public safety also commercial services will become reality
Time has come for Proximity-based applications - D2D
• Phantom Cell - Architecture including D2D
• Many challenges to be solved for: D2D Discovery and D2D communications
– Resource Groups: Solution for efficient D2D Discovery
…. Still a lot of research to be performed!
Summary
S2S
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DOCOMO Communications Laboratories Europe GmbH Landsberger Strasse 312 – 80687 Munich, Germany Phone: +49 (89) 56824-0 | www.docomolab-euro.com
Dr. Matthias Lott lott@docomolab-euro.com
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Topology Scenarios D2D Communication Options
via Gateway
• D2D Communication Paths
Ib.
II.
via eNB Direct Communication
Ia.
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• Policy and user choice can set the ProSe feature to enable a ProSe-enabled device (UE) (TR 22.803):
– to discover others in its proximity but not be discoverable;
– to be discoverable but not be able to discover others in its proximity;
– to discover others in its proximity and be discoverable;
– to disable discovery (disable ability to be discoverable and to discover others).
– to revoke being discoverable by others (i.e. be discoverable by a UE at one time, and then not discoverable by the same UE at another time);
– to discover others of interest, or to restrict discoverability to others of interest, where interest is defined in a ProSe-enabled application per user, group of users, or category of users;
• Operator policy and user choice can be different for licensed vs. unlicensed spectrum.
Device Status
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• 3GPP Architecture for
Machine-Type Communication
(TS 23.682 v11)
3GPP MTC Architecture
S6n
Services Capability
Server ( SCS )
Gi / SGi
Tsp Control plane
User plane
Indirect Model
Direct Model
Hybrid Model
GGSN / P - GW
MTC - IWF
SMS - SC / GMSC / IWMSC
2
1
1
T 4
Rf / Ga S 6 m
T 5 c
Um / Uu /
LTE - Uu
MTC UE Application
MME
HPLMN
VPLMN
Gi / SGi
SGSN
S - GW
UE
MSC
RAN
T 5 b T 5 a
CDF / CGF
Tsms
Application Server ( AS )
1
Application Server ( AS )
2
IP - SM - GW
HSS
2 +
SME
MTC AAA