Outline - TSDSI | Welcome to TSDSI€¦ · PPT file · Web view · 2015-07-17Device-to-Device...

Device-to-Device (D2D) Communication

Networks Lab, TCS Research

TSDSI SG1 F2F meeting, IEEE Bangalore, July 2015

2 Experience certainty.

Copyright 2014 | Tata Consultancy Services Limited | Strictly Confidential

Outline Introduction Evolution towards 5G

Introduction – Why D2D Communication D2D Communication D2D Offloading

D2D Research at TCS Standardization of D2D Communication Conclusion



Growth of Networks Challenges for future wireless communication -

Massive growth in connected devices Smart phones, laptops, sensor devices, etc

Massive growth on network traffic Almost 1000+ times or more 61% CAGR expected

Wide range of applications and their requirements Social media, video on demand, live TVs, gaming, IoT, etc

Sea of devicesExponential Growth of Network Traffic

Wide range of

requirements



Can we Match to the Growth? Both backhaul as well as the access capacity should be increased Increasing Access Capacity…

Add more BTSs At present we have 7,36,654 BTS in India Tata Teleservices alone has 3000+ BTS in Bangalore New BTS will add CAPEX and OPEX

Release new spectrum Huge cost for the operators Seems to be a challenge

• Only 200+ MHz available in India Improve the spectral efficiency

Not possible always• Theoretical Limits are being reached

Usability is the key • Yet to deploy LTE Rel 8

» Spectral efficiency = 4-5 Increasing Backhaul Capacity

Nationwide optical fibre backbone Only a few operators can do this

CAPEX and OPEX issue again

Source – Huawei - The_full_spectrum_of_possibilities

Source – ITU -Link: http://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-M.2243-2011-PDF-E.pdf


D2D Communication Purpose

To propose/design optimal scheduling algorithms for D2D uplink/downlink in data networks such as HSPA, LTE, LTE-A, etc., networks.

D2D communication model for LTE/LTE-A systems that can be used for mobile data offloading

Why D2D?Possible to have direct communication between close proximity UEs

Reuse of cellular resources –use cellular spectrum D2D users can use same resource blocks of the cellular users Higher and better network performance than WiFi, Bluetooth, etc. Viz: in social networking, online gaming, multimedia sharing, etc.

Gain and gain Reuse gain, proximity gain, hop gain Higher data rate, low end-to-end delay

Emergency services



Big Question Is it possible for UEs in proximity to communicate among themselves ?

Regular Communication Model In coverage D2D Communication Model

eNB

Data PathControl Path (C-Plane)

D2D (U-Plane)

eNB

Control Path (C-Plane)Data Path

Device to Device (D2D) Communications


D2D vs. M2M and Ad-hoc Networks Machine to Machine (M2M) Communication

Machine Type Communication – 3GPP TR 22.368 D2D vs. M2M

D2D vs. Ad-hoc NetworksD2D Ad-hoc Networks

Licensed and Free Spectrum Free SpectrumQoS can be ensured No QoS guarantee

Seamless Connectivity Manual ConnectivitySecurity is guaranteed Security is a challenge

D2D M2MDescribes connectivity Services Application Oriented

Direct device to device communication

Remote devices communicates through a centralized node

Access specific Access agnosticLocal comm. improves spectral

efficiencyNot applicable



Classification based on Frequency of use In-band - Network assistedOut-band - Independent

Classification based on ServicesEmergency services (both in/out band)Commercial services (in-band only)

Emergency Services Commercial ServicesD2D

eNB

Control PathData Path

D2D

eNB

Control PathData Path

D2D Communication - Classification



TDD Frame structure

Technology behind D2D Communication Discovery and classifications

Discovery types Proactive – Discovery signal is per group of UEs or all UEs Reactive – Discovery signal is per UE

eNB Classifies D2D and Cellular pairs Based on - location, distance, power control, interference, etc.

Restructuring of the Scheduling procedures Scheduling of cellular and D2D transmissions

Overlapping - non-interfering same RB scheduling Non-overlapping – unused cellular RBs used for D2D

D2D frame usage In TDD – UL sub-frame (U) will be used In FDD – UL spectrum will be used

RBs can be re-used through scheduling



Challenges in D2D Communications Communication Challenges

Location of the devices Ensure accuracy

Signaling techniques need to be amended Signaling overhead to be evaluated

New Modulation Schemes can be proposed Cellular: SC-FDMA Tx (UE-eNB) and OFDMA Rx (eNB-UE) D2D: SC-FDMA receiver in UE (UE-UE)

Interference Management To ensure interference below threshold in case of overlapping D2D

Power control model Select the transmit power depending on distance/channel characteristics

Channel model Short distance (indoor/outdoor) channel model can be explored

D2D traffic characterization What percentage of the users are D2D?



Why LTE D2D Communication ?

LTE-D2D

Strong Resource Management

Tighter spectrum reuse

Offloading can be achieved

Better Performance

Higher data rate, low end-to-end

delay

Energy Efficient

Reliability and Scalability

Operator initiated Services

Security can be guaranteed

Regulatory and Standardization

Under 3GPP and TSD



D2D Communication @ 3GPP Standardization attempts under 3GPP Rel 12/13 (ProSe) - 3GPP TR

21.905 / TR 22.803 / TR 36.814/ TR 36.843 Discovery for ProSe

UEs at proximity should identify each other using E-UTRA/EPCProSe D2D communication

Communication between two UEs in proximity Path can be established directly or through eNB

UsageCommercial /SocialPublic Safety (with and without coverage)Network Offloading

UE -1

ProSeAPP LTE - Uu

E - UTRAN

UE-2

ProSeAPP

EPC (MME,

S/PGW)

S 1

ProSeAPP Server

SGi

ProSe Function

PC 4 PC 2

PC 5 LTE - Uu

PC 3

PC 1

PC 6

HSS/SLP

Source - 3GPP-23.703-V12.0.0

ProSe System Architecture



D2D Use Cases Usecase – 1

M2M communication using D2D underlaying LTE eNB classifies, schedules the communication

Usecase – 2 M2M communication using D2D offloading

Offloader can relay data



Direct M2M under LTE Direct M2M for close proximity devices

Communicate directly whenever close to receiver (UE/eNB/AP) eNB takes care of Interference and control management Classification, scheduling, etc. through APPs

M2M offloading for bad-channel devices Remote sensors, non-LOS connections Foreign and unpredictable channel conditions Offload message packet to a nearby offloader Improved spectral efficiency and system utilization

Examples Offloading of images from cam to mobile Direct songs/images transfer from smartphone to car/home AP



Evaluation of D2D Communications (1/3) Network assisted D2D is considered

Carrier frequency – 2 GHz eNB needs to identify the D2D and cellular pairs

3GPP’s D2DSS signaling for discovery Two types of communications will exist

Existing cellular communications and D2D Should not interfere in case of overlapping communication

Broad Assumptions D2D does not use the full duplex on a given carrier Mobility – 3km/hr Full synchronization between UEs and UE to eNB is possible Unicast communication only



Evaluation of D2D Communications (2/3) Simulations

30% average D2D users considered Static users only

Discovery and classification Assumed 3GPP specifications for discovery Proximity based classification by eNB - proactive

Optimal D2D scheduling under LTE Two phase scheduling Modelled as a Binary Integer Program Solved using Matlab

Power control Simultaneous transmission : non-interfering

QoS Improvement Reduced delay Energy efficient Improved spectral efficiency

Network and per-user spectral efficient improved• 15% at-least

Simulation topology: Cellular vs. D2D

UE1

UE2

UE3eNB

UE1

UE2

UE3eNB



Evaluation of D2D Communications (3/3) Emulations

Through test-bed level implementation WiFi AP as LTE eNB, smartphones as UEs

Discovery based on signal strength and location Service classification – D2D/Cellular

• Depending on location, distance, interference, etc. Power control mechanism for smartphones

eNB computes required Tx power for small D2D distance eNB notifies UE the reduced Tx power, modulation, timing, etc.

TDD scheduling scheme implemented D2D & cellular transmissions on same channel Time synchronization is assumed

APP based deployment JAVA API for eNB

Desktop with Ubuntu – 14.04 as eNB Livetek WiFi adapter

Android APP for Tx, Rx (UEs) Lenovo Nexus 5, Android KitKat 4.4.2

Control Flow Diagram for D2D

Test-bed Topology



D2D

eNB

Control PathData PathOffloading Path

D2DD2D

D2D Offloading If the load at eNB is high or if the channel between the UE - eNB is

poor Offloading via another UE can be planned

Multiple UEs may be involved Effective data rate/spectral efficiency can be improved Energy saving can be achieved Both licensed and un-licensed spectrums can be used

Challenges in D2D Offloading Traffic characterization

Distorted user discovery Synchronization between UEs

Network assisted vs. independent Interference management and Scheduling Energy consumption due to sensing and location updates



D2D Offloading Evaluations Simulations

Matlab based offloading scheduling under LTE Static users, 30% are distorted (poor signal) Cell radius: 300 mt, D2D range: 5-30 mts Fixed/adaptive modulation scheme

Channel modelling Channel between UE-eNB and UE-UE Short term, long term fading is considered

Scheduling Round robin scheduling D2D transmission scheduled prior to relay

QoS Improvement Guaranteed delivery for distorted users

Low delay due to reduced failure rate Improved spectral efficiency

User and system throughput improved : 30-40% Better system utilization



D2D Offloading - Discussions Practical Deployment Scenario

Single operator case Billing is the key issue Traffic characteristics

• Data usage pattern of UEs • Signaling for distorted users – eNB assited/Distributed

Multiple operators case Further research required

Standardization Mobility modeling & dynamic classification

Location of UEs – discovery and classification Modeling the mobile channel

Secure D2D communication Control signaling, authentication, connection timing, etc.

Power-control at UE Equipment manufacturers should be involved



D2D provides one more mechanism for network offloading Is now on the way towards standardization through 3GPP

Rel 12 ProSe Discovery, ProSe Communication One-to-Many ProSe UE-to-NW relay (with no RAN impact), ECP support for WLAN

Rel 13 Communication: One-to-One communication; direct and via eNB, Service

continuity Discovery: Interaction with 3rd party apps & UE terminal apps

LTE-D2D is being positioned for emergency services in the US Is a new tool for social networking Many issues are still being unresolved and thus a fertile ground

for research

Conclusion



References Alastair Brydon ,"Opportunities and threats from LTE Device-to-Device (D2D)

communication",, Unwired insight - The wireless blog, Feb. 2014 X. Lin, J. G. Andrews, A. Ghosh, and R. Ratasuk, “An overview of 3GPP device-

to-device proximity services,” IEEE Communications Magazine, December 2013 X. Wu, S. Tavildar, S. Shakkottai, T. Richardson, J. Li, R. Laroia, and A. Jovicic,

“FlashLinQ: A synchronous distributed scheduler for peer-to-peer ad hoc networks,” in IEEE Allerton Conference on Communication, Control, and Computing, 2010, pp. 514–521

K. Doppler, M. Rinne, C. Wijting, C. Ribeiro, and K. Hugl, “Deviceto-device communication as an underlay to LTE-advanced networks,” IEEE Communications Magazine, vol. 47, no. 12, pp. 42–49, 2009

3GPP TR 23.703, “Study on architecture enhancements to support proximity services (ProSe) (Release 12),” v. 12.0.0, February, 2014

3GPP TR 22.803, “Feasibility study for Proximity Services (ProSe) (Release 12),” v. 12.2.0, June, 2013.

Thank You

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