evolution of lte towards b4g (2014)

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Evolution of LTE Towards B4G and Beyond

Yongjun Kwak, Ph.D.([email protected])

Samsung Electronics Co., Ltd.Digital Media and Communications R&D Center

2

Table of contents

3GPP Standardization Status

Candidate Technologies for B4G and Beyond• Device to Device (D2D) Communication• Full Dimension MIMO (FD‐MIMO)• CoMP with Non‐Ideal Backhaul• Network Assisted interference Cancelation and Suppression (NAICS)• Millimeter Wave (mmWave) Communication

Concluding Remarks

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3GPP Standardization Status

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3rd Generation Partnership Project Initiated in December, 1998 for development of wireless communication standards

Collaboration between groups of telecommunications associations• China: CCSA (China Communications Standards Association)

• Europe: ETSI (European Telecommunications Standards Institute)

• Japan: ARIB (Association of Radio Industries and Businesses), TTC (Telecommunication Technology Committee)

• Korea: TTA (Telecommunications Technology Association)

• USA: ATIS (Alliance for Telecommunications Industry Solutions)

Specification work done in Technical Specification Groups• GERAN (GSM/EDGE Radio Access Network): GERAN specifies GSM radio technology, including GPRS and EDGE• RAN (Radio Access Network): RAN specifies the UTRAN and the E‐UTRAN• SA (Service and System Aspects): SA specifies service requirements and overall architecture of 3GPP system• CT (Core Network and Terminals): CT specifies the core network and terminal parts of 3GPP

© SAMSUNG Electronics Co., Ltd. Confidential and Proprietary

W‐CDMA (1999)

W‐CDMA (1999)

HSDPA(2002)HSDPA(2002)

HSUPA(2005)HSUPA(2005)

LTE(2008)LTE

(2008)LTE‐A (2010)LTE‐A (2010)

B4G (2014)B4G (2014) 5G5G

CDMA, QPSK DL: 16QAMAMC, HARQ

UL: AMC, HARQ DL: OFDMA, MIMOUL: SC‐FDMA

CoMP, CA, eICICUL: MIMO

backward compatible backward compatible

Rel‐99 Rel‐5 Rel‐6 Rel‐8 Rel‐10

Small cells, FD‐MIMO

backward compatible?

Rel‐12

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Industry Participation in 3GPP Over 100 companies involved in LTE specification development

• Mobile Vendors: Samsung, Nokia, Blackberry, LGE, ZTE, Pantech, Motorola, HTC, Apple, …

• System Vendors: Ericsson, Huawei, Alcatel Lucent, Nokia Siemens Network, …

• Chipset Vendors: Qualcomm, Intel, MediaTek, Broadcom, NVIDIA, …

• Service Operators: CMCC, Vodafone, Orange, Verizon, AT&T, KDDI, Sprint, Deutsche Telekom, Korea Telecom, SK Telecom, NTT DOCOMO, Telecom Italia, Softbank, …

• Measurement Instrument Vendors: Agilent Technology, NI, Rohde & Schwarz, …

• Terminal Location Providers: TruePosition, Polaris Wireless, ..

• Research Firms: InterDigital, ETRI, ITRI, III, …


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LTE Release 8: First LTE Specification


10ms radio frame, Tf

#1 #2 #3 #4 #5 #6 #7 #8 #9Subframe

Slot, Tslot 0.5 msec

1msec

#0

Resource Block (RB) Resource element

(k,l)

l=0 l=NsymbDL-1

Symbol

Subcarrier15kHz

k = nPRB*NSCRB

4x4 DL MIMO

OFDMA / SC‐FDMA: 1.4MHz – 20MHz Flat RAN architectureKe

y techno

logies

Requirements Target

Peak transmission rate (Mbps) >100 (DL), >50 (UL)

Peak spectral efficiency (bps/Hz) >5 (DL), >2.5 (UL)

Average cell spectral efficiency (bps/Hz/cell) >1.6–2.1 (DL), >0.66–1.0 (UL)

Cell edge spectral efficiency (bps/Hz/user) >0.04–0.06 (DL), >0.02 –0.03 (UL)

User plane latency / Control plane latency (ms) < 10 / <100

7

LTE‐Release 10: LTE Advanced (LTE‐A)


Key techno

logies

Carrier Aggregation

8x8 DL MIMO

4x4 UL MIMO

Time‐domain Inter‐cell Interference Coordination

Cell range expansion

Almost Blank Subframe

Requirement Target

Peak transmission rate (Mbps) 1000 (DL), 500 (UL)

Peak spectral efficiency (bps/Hz) 30 (DL), 15 (UL)

Average cell spectral efficiency (bps/Hz/cell) 2.4–3.7 (DL), 1.2–2.0 (UL)

Cell edge spectral efficiency (bps/Hz/user) 0.07–0.12 (DL), 0.04 –0.07 (UL)

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LTE‐Release 11: Network Coordination for LTE


Key Technology: CoMP (Coordinated Multi‐Point Transmission and Reception)• Allows network to coordinate wireless resources (time, frequency, transmission power, etc)• Significant improvement in system performance (Average: 20~30%, Edge: 30~40%)• Well suited for C‐RAN (Centralized Radio Access Network)

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Ongoing LTE Enhancement


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LTE Roadmap

1H 2H 1H 2H 1H 2H 1H 2H 1H 2H 1H 2H

2011 2012 2013 2014 2015 2016

Release 11(LTE‐A)

Release 12(Beyond 4G)

Release 13(Beyond 4G)

2011.09

Stage 1 Stage 3 ASN.1 Freeze

2011.03

Stage 1Rel‐12 and onwards WS

2012.62014.06

Stage 3 ASN.1 Freeze

2014.09

2012.09 2013.03

Release 14(5G)

1H 2H

2017

Projected completion of R13

Projected completion of R14


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Candidate Technologies for B4G and Beyond

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Device to Device Communication

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Device to Device (D2D) Overview Cellular communication

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Device to Device (D2D) Overview Direct communication between devices


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D2D Techniques Wifi‐Direct

• Target use case: peer to peer connectivity• Using unlicensed band (2.4GHz, 5GHz) based on Wifi• Currently used (standardization completed)

D2D proximity based service (D2D ProSe) in LTE• Target use case: Discovery based proximity service (Advertisement, SNS, etc)• Using licensed band (*850MHz1,3, 900MHz2, 1800MHz1,2, 2100MHz3) based on LTE• Currently standardized in 3GPP


* (1: SK Telecom, 2: KT, 3: LG Uplus)

Wifi‐Direct use cases

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Wifi‐Direct vs. D2D ProSe

• Wifi‐Direct : two step discovery • Device discovery: broadcast request

followed by unicast response• Service discovery: Inquest request

followed by unicast response

• LTE ProSe : one step discovery • Device broadcast its discovery and

service information together• Faster discovery with low power

consumption

Step 1 device discovery

Device & service discovery in one stepStep 2 service discovery

Wifi‐Direct vs. D2D ProSe

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Delay ▶ Long discovering time for service discovery

Scalability ▶ The number of connected devices is limited.

Range ▶ Small range (less than 100 meter)

Power Consumption ▶ Asynchronous carrier sensing protocol

Interference ▶ Low reliability of the radio link

Limitation of Wifi‐directWifi‐Direct vs. D2D ProSe

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D2D Prose: Component Techniques

Peer discovery• UE discovers other UEs proximate to itself• Mainly for commercial use case

Direct communication• UE transmits data to other UE(s) with network

assistance inside network coverage

• Broadcast communication is studied in Rel‐12

Out of network coverage• D2D communication should also be supported in

out of network coverage• Key feature for public safety use case


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D2D Discovery: Physical design


Design principle• Type 1 discovery

— Network configures resource pools for D2D discovery— D2D UE randomly selects a resource inside the resource pool for the transmission D2D

UE tries to receive multiple discovery signals inside the resource pool• Type 2 discovery

— Network allocates a UE where to transmit its discovery

Resource pool for D2D discovery

WAN data WAN data WAN data

... ...

...

...



PR

Bs

subframes

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D2D Discovery: Possible scenario


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D2D Direct communication: Synchronization


Synchronization procedure• If no synchronization source is detected by a UE, a UE may transmit D2DSS (D2D

sync Signal) • D2DSS relaying is considered• UE synchronize its receiver to the detected D2DSS transmitted from a sync source• UE detects a sync source as follows

— ENB synchronization has the highest priority as a sync source for D2D UEs— Synchronization sources which are UEs within network coverage have a higher priority

than synchronization sources which are UEs outside network coverage

CelleNB

D2D UE3: Independent Sync source

cluster

D2D UE1

D2D UE2

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D2D Direct communication: Data scheduling

© SAMSUNG Electronics Co., Ltd. Confidential and Proprietary© SAMSUNG Electronics Co., Ltd. Confidential and Proprietary

Cell

eNB

clusterUE1

UE5

UE3UE4

Tx

RxTx Rx

UE2

Tx

Rx

UE6Rx

Scheduling

D2D Data (Broadcast)

Resource allocation procedure• Mode 1: eNB schedules the exact resources used by a UE to transmit direct data

—Mainly used for inside network coverage

• Mode 2: a transmitting UE on its own selects resources to transmit direct data—Mainly used for out of network coverage

• To be discussed in 3GPP how to schedule for partial coverage case

Mode 1 resource allocation

Mode 2 resource allocation

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Full Dimension MIMO

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Full Dimension MIMO (FD‐MIMO) Concept Utilization of two‐dimensional antenna array

• Allows flexible beamforming in both azimuth and elevation domain

High order MU‐MIMO• Simultaneous transmission to large number of UEs

4xCPRI

IP network

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2 Dimensional Beamforming Example 1: 70/70 degrees without down tilt

Example 2: 70/40 degrees without 30 degrees down tilt


2×8 antennas 4×8 antennas 8×8 antennas

2×8 antennas 4×8 antennas 8×8 antennas

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1‐Dimensional Array (64x1): dH = 0.5λ


902 701

100

,70

1

1

110

,90

2

2

MU interference virtually non‐existent using 64‐antenna horizontal beamforming

At 700MHz, 64 antennas with half lambda spacing is 15m long!

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2‐Dimensional Plane (8x8): dH = 0.5λ, dV = 0.5λ


Azimuth

Elevation

Low MU interferencefrom horizontal beamforming

High MU interferencefrom vertical beamforming

701 902

1001 1102

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2‐Dimensional Plane (8x8): dH = 0.5λ, dV = 4λ


701 902

1001 1102

AzimuthLow MU interferencefrom horizontal beamforming

Elevation

Low MU interferencefrom vertical beamforming

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FD‐MIMO Standardization Status


New scenarios New channel model

New antenna model New path loss and LOS probability model‐ Simplified model Element generated model‐ Example: 10° vs. M=8 element pattern for vertical domain

TR36.814 New Model

1

1

1

1

1

‐ Scatters in vertical domain

‐ Correlation for LS parameter

DS

DS

K

SF

ASD

ASA

K SF ASD ASA1

1

1

1

1

1

1

DS K SF ASD ASA ESD ESADS

K

SF

ASD

ASA

ESD

ESA

TX

RXASD

ASAESD

ESA

Scatter

‐ Pathloss gain for high‐rise UE‐ LOS prob. of high‐rise UE

PL=PLOS(HUT)

PL=PNLOS(HUT=1.5m)Height gain= a(HUT‐1.5)

UMi (Urban micro) UMa (Urban macro)

High‐rise scenario Stadium, mall, airport

6~8floors

10m

TX

6~8floors25m

20floors

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FD‐MIMO System Level Simulation Simulation Setup:

• Two tier 57 sectors

• K=10~30 UEs per sector

• Center frequency 2GHz, bandwidth 10MHz

• UE speed 3km/h uniformly distributed

• UE: 2 Rx, 1Tx


NT-V

NT-H NT-H

NT-V

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• Element gain- 3dB BW-V:90 degree- 3dB BW-H:90 degree- Peak gain: 6.4dBi

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FD‐MIMO Evaluation Results (1/3) Performance with minimum spacing of half λ or two λ between elements

• NT = NV x NH= 8, 16, 32, 64 antenna elements• With 2λ spacing in vertical domain, achieve 57% gain over half λ spacing• Metric: Average Cell throughput (bps/Hz)


(V/H)=(0.5 λ/0.5λ) spacing (V/H)=(0.5 λ/2λ) spacing

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CoMP with Non‐Ideal Backhaul

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Inter‐eNB CoMP with Non‐Ideal Backhaul

Release 11 CoMP Release 12 CoMP‐NIB

• Focuses on air‐interface aspect only

Relies on proprietary interface between eNBs

Not designed for robust performance in networks with non‐ideal backhaul

• Should support network interface for inter‐eNB coordination

Support coordination among eNBs of different vendors

Design to provide robust performance even in networks with non‐ideal backhaul

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Centralized Scheduling Between eNBs Stage 1: Resource coordination

• Central resource coordinator decides which TP gets which frequency/time resource• Relatively robust against backhaul latency

Stage 2: UE selection and link adaptation• Conveys resource coordination result to TPs

— Each TP is notified of its own resource allocation and those of neighboring TPs

• Each TP runs channel opportunistic scheduler based on latest CSI from UEs


UEs reports CSI to eNB

eNBs forward CSI to resource coordinator

Resource coordinator decides which eNB gets

which resource Resource coordinator notifies resource allocation to eNBs

eNBs uses latest CSI and resource coordination of other eNBs to perform scheduling

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Two‐Stage Resource Allocation Stage 1: Resource coordination

• Central resource coordinator decides which TP gets which frequency/time resource• Relatively robust against backhaul latency

Stage 2: UE selection and link adaptation• Conveys resource coordination result to TPs

— Each TP is notified of its own resource allocation and those of neighboring TPs

• Each TP runs channel opportunistic scheduler based on latest CSI from UEs

Impact of time delay• Resource coordination: less sensitive can handle larger time delays• UE selection and link adaptation: more sensitive large performance degradation


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Inter‐eNB CoMP Evaluation Results Coordination size: N cells

• 2N‐1 ON/OFF combinations considered• Left table considers 7 combinations

Resource coordinator selects ON/OFF combination with best metric

Resource coordinator informs each cell’s scheduler of resource allocation

• Cell2: no resource assigned• Cell1: resource assigned• Cell3: resource assigned

Resource coordinator informs each cell’s scheduler of interfering cells

• Cell2: ‐• Cell1: notified that Cell3 is interfering• Cell3: notified that Cell1 is interfering

Each cell’s scheduler selects UEs and adjusts MCS level according to interfering cell(s)


Cell1 Cell2 Cell3 Sum Rate

Alt 1ON/OFF ON ON ON

5Rate 2 1 2

Alt 2ON/OFF ON ON OFF

4.8 (↓0.2)Rate 2.3 (↑0.3) 2.5 (↑1.5) ‐

Alt 3ON/OFF ON OFF ON

6.5 (↑1.5)Rate 3.5 (↑1.5) ‐ 3 (↑1)

Alt 4ON/OFF ON OFF OFF

4 (↓1)Rate 4 (↑2) ‐ ‐

Alt 5ON/OFF OFF ON ON

5.5 (↑0.5)Rate ‐ 2.5 (↑1.5) 3 (↑1)

Alt 6ON/OFF OFF ON OFF

4 (↓1)Rate ‐ 4 (↑3) ‐

Alt 7ON/OFF OFF OFF ON

4.5 (↓0.5)Rate ‐ ‐ 4.5 (↑2.5)

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Network Assisted Interference Cancellation and Suppression

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Network Assisted Interference Cancellation/Suppression Advanced receivers for terminals

• Can boost system performance and end‐user experience

• Requires highly complex terminal implementation

NAICS (Network Assisted Interference Cancellation/Suppression)

• Network provides information on interference to terminal

• Based on network information, terminal applies advanced receiver


NAICS for inter‐cell interference NAICS for intra‐cell interference

• Cell A & Cell B exchange info on PDSCHA & PDSCHB

• Info on interference is forwarded to terminals

Inter‐cell interference cancellation/suppression

• Info on PDSCHA & PDSCHB are available at eNB

No need for information exchange

• Info on interference is forwarded to terminals

MU‐MIMO interference cancellation/suppression

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NAICS Evaluation Results Joint symbol level reduced maximum likelihood receiver

• Input to turbo‐decoder is calculated assuming knowledge of interference modulation— Random interference of a discrete constellation (QPSK, 16QAM, 64QAM, etc)

• LLR calculation is done assuming interference of a discrete constellation— Compared to a zero mean Gaussian distribution


IsInmS

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I nmS

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LLR

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Mean Packet Rate (bps/Hz) Packet Rate @5%‐tile (bps/Hz) Packet Rate @50%‐tile (bps/Hz)

MMSE‐IRC 1.66 0.0% 0.26 0.0% 1.23 0.0%R‐ML 1.82 9.4% 0.30 17.0% 1.42 15.4%

Mean Packet Rate (bps/Hz) Packet Rate @5%‐tile (bps/Hz) Packet Rate @50%‐tile (bps/Hz)

MMSE‐IRC 1.10 0.0% 0.12 0.0% 0.71 0.0%R‐ML 1.31 19.0% 0.17 32.5% 0.92 28.8%

Simulation results @60% RU for NAICS scenario 1

Simulation results @40% RU for NAICS scenario 1

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Millimeter Wave Communication

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Spectrum Candidates Requirement: Large Chunks of Contiguous Spectrum

• Examples: 13.4~14 GHz, 18.1~18.6 GHz, 27~29.5 GHz, 38~39.5 GHz, etc.

EESS (Earth Exploration‐Satellite Service) FSS (Fixed Satellite Service) RL (RadioLocation service), MS (Mobile Service) FS (Fixed Service) P‐P (Point to Point) LMDS (Local Multipoint Distribution Services)

42

Friis’ Equation in Free Space (1/2)


43

Friis’ Equation in Free Space (2/2)


44

Prototype for mmWave Beamforming Samsung’s demo system for mmWave mobile technology

• Adaptive antenna array technology• Evaluated in outdoor environment


Carrier Frequency 27.925 GHz

Bandwidth 500 MHz

Max. Tx Power 37 dBm

Beam width (Half Power) 10o

45

Test Results – Range Outdoor Line‐of‐Sight (LoS) range test

• Error free communication possible at 1.7 km with > 10dB Tx power headroom

• Pencil BF both at transmitter and receiver enables long range communication


46

Test Results – Mobility Outdoor Non‐Line‐of‐Sight (NLoS) mobility tests

• Adaptive joint beamforming and tracking effective at 8 km/h mobility even in NLOS


47

Test Results – Building Penetration Outdoor‐to‐Indoor penetration tests

• Most transmissions successfully received by an indoor MS from an outdoor BS• Successful penetration of transmissions through tinted glasses and doors


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Concluding Remarks

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Evolution Towards B4G and Beyond… Wireless standards have evolved throughout the years

• 1G (AMPS) 2G (GSM, IS‐95) 3G (W‐CDMA, cdma2000) 4G (LTE, Wibro)

With each generation came new features and capabilities

• 1G 2G (1990’s): Analog Digital (10kbps)

• 2G 3G (~2000): higher than 200kbps, CDMA

• 3G 4G (~2010): higher than 1Gbps, OFDMA, MIMO

• 4G B4G (~2015): FD‐MIMO, small cell enhancement, D2D

• B4G 5G: ?

B4G and 5G evolution will bring in yet another set of features

• To handle explosion of wireless traffic

• To be more cost effective

• To handle different services, communication scenarios, devices


evolution of lte towards b4g (2014)

Sports

mimo ul

harq ul

eicic ul

ul peakspectralefficiencybpshz

proprietary wcdma

fdmimo backwardcompatible

scfdma comp

qam amc