Overview of 5G Research @ IITH
Dr.Kiran Kuchi

Associate Professor
Department of Electrical Engineering
IIT Hyderabad1

More than 50 Billion Connected DevicesMore than 50 Billion sensorized connected devicesby 2020

Proliferation of Smart phones, Machine-to-Machine(M2M), Internet of Things (IoT)
Serving Multiple Applications over Multiple Networks
Convergence between Cellular, sensors, M2M/IoT
Networked society

Wireless sensors – smart cities

2Requirements
User requirements

Always connected to the cloud
Uniform experience independent of user locationvariation in data rates 100Kbps to 1Mbps– even in 4G

5G should offer 100-1000x increase in data rates
Ultra low latencies

Network requirementsReduce cost/bit – Maximize bits/sec/Hz
Reduce Energy/bit – Energy efficiency
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ITU Future Technology Trends
for 5G

Working Party 5D Document 5D/441
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Massive MIMO
Small Cells
Support for M2M and IoT
Cloud RAN
Tight Integration between WLAN and LTE
LTE operation in unlicensed spectrum (LTE-U)

Millimeter waves

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5G research @IITH
Cloud RAN Waveform Design for 5G
 Licensed Assisted Access (LAA) LTE operation in unlicensed bands
 TV whitespaces
 Massive MIMO and Millimeter waves
 IoT chip design
 Contributions to TSDSI (Telecommunications
Standards Development Society, India)
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Cloud RAN

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CRAN Architecture
 3GPP LTE introduced COMP
 BSs are connected to a central
unit (cloud) through fiber toremote radio head-ends(RRH) using CPRI protocol
 Baseband signal processing
and scheduling at the cloud Interference mitigation
 Load balancing throughscheduling

CRAN Clustering

In real life, the size of the cloud is limited
Cluster: Groups of BSs are connected to a central processor
Cloud processing is applied in each cluster independentlyCluster edge users interference will be highStatus of CRAN prototype
Tejas Networks, an Indian telecom vendor supplied commercial
grade BS hardware with RRHs
Centralized BS implemented using TI multi-core DSP processors
UE implemented using same BS quality hardware
Baseline: LTEAdditional enhancements

The prototype would implement clusters of BSs where cooperation isapplied in each clusterNetwork MIMO operation: Non-linear Tomilson-Harashama precoding(THP)Feedback of neighbouring channel states from UE

Cluster size: approx 10 BS; Inter-cluster interference effects will be captured

First filed trial in 6-months
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LTE Operation in Unlicensed
Bands10

LTE unlicensed• Licensed spectrum remains 3GPP operators’ top priority todeliver advanced services and user experience• Opportunistic use of unlicensed spectrum is becoming animportant complement for operators to meet the growing
traffic demand• Moving forward 3GPP operators will have two options tooffload traffic to unlicensed spectrum:– Wi-Fi (via LTE/Wi-Fi interworking)– LTE over unlicensed• It will be up to individual operator to choose whichapproach to use, which will depend on a number of factors
Source:http://www.3gpp.org/ftp/Information/presentations/presentations_2015/2015_
01_3GPP_unlicensed_Dino_Flore.pdf

LTE-WiFi interworking• Framework being developed since the first release ofLTE-8– With tighter and tighter forms of interworking added insubsequent releases• New proposal for even tighter radio-level interworking
are currently being evaluated for Rel-13, including:– LTE/Wi-Fi aggregation– Enhanced network controlled mobility, via enhanced UEmeasurement reporting and network steering capabilities– Interface between LTE eNBs and Wi-Fi APs

LTE over unlicensed• The discussion was kicked off by a workshop in Jun. 2014
which established the initial priorities (RWS-140029):– 5 GHz band
– Global solution that can work across regions– Licensed-Assisted Access (LAA) operation• Aggregation of a primary cell, operating in licensed spectrum todeliver critical information and guaranteed Quality of Service, with asecondary cell, operating in unlicensed spectrum to opportunistically
boost data rate
• The secondary cell operating in unlicensed spectrum can beconfigured either as downlink-only cell or contain both uplink anddownlink– Fair coexistence between LTE and Wi-Fi as well as between LTEoperators

Licensed-Assisted Access (LAA)• The feature is targeting completion in Rel-13,
which is scheduled to freeze in Mar. 2016
• Item (SI) was approved by RAN in Sep. 2014
and is scheduled to complete in Jun. 2015
– Main SI goal: study the LTE enhancements needed
to operate in unlicensed spectrum and to ensure
fair coexistence with Wi-Fi• The detailed SI description is available in RP141817
One US operator is going to launch pre-rel-13 LTE-LAA
products. There is strong support for LTE-LAA feature fromsome major European operators as wellLAA-LTE: Design Targets andFunctionalities• Agreed design targets:– Single global solution allowing compliance with any regional regulatory requirements– Effective and fair coexistence with Wi-Fi– Effective and fair coexistence among LAA networks deployed by different operators•

Based on the above targets, it was agreed that at least the following functionalities
are required for LAA:–––––•Listen-before-talk (Clear channel assessment)
Discontinuous transmission on a carrier with limited maximum transmission duration
Dynamic Frequency Selection for radar avoidance in certain bands/regions
Carrier selection
Transmit Power Control

On fair coexistence with Wi-Fi––

Initial qualitative definition provided in the SI description:[…] LAA should not impact Wi-Fi services(data, video and voice services) more than an additional Wi-Fi network on the same carrier; thesemetrics could include throughput, latency, jitter etc. […]Exact metrics to be defined in the coexistence studyPresent Status in 3GPP
• Presently Wi-Fi and LAA-LTE do not currently
use a common media access mechanism thatwould implicitly result in fair sharing• 3GPP presently uses media sharing
mechanisms defined in ETSI 301 893 which isthe basis of compliance regulations for the5GHz band in Europe

LTE-LAA Operational Scenarios• In LTE-LAA channel reservation is done at thebase station– Multiple User equipments (UEs) are served by the BS
in scheduled mode
– Option-1: LTE-LAA operates in down link (DL) onlymode; Uplink (UL) date is carried in the licensedcarrier– Option-2: LTE-LAA operates in both DL and UL• UL in scheduled mode; user transmits only if interference isbelow a threshold; channel reservation procedure is notapplied by LTE-LAA UE in ULChannel access mechanisms
considered in 3GPP• LTE-LAA study item considers Listen Before Talk (LBT)
with fixed back-off window (as defined in ETSI 301893)– Works well under low load and light interference– Enhanced channel access mechanisms may be consideredduring specification phase• WiFi uses CSMA with exponential back-off– Designed to handle high system load and adverse
interference conditions• LTE-LAA is expected to study the use of variable backoff window during the subsequent study phases

Problem Statement• In LTE-LAA study, channel reservation is doneat the base station• A new mechanism needs to be introduced toincrease channel reservation time of LTE-LAA
BS and yet ensure fairness to WiFi

Waveform Design for 5G20

5G Waveform Design• In addition to providing high data rates 5G expected toenable new applications with– ultra-low latency– low power consumption• Limitation of OFDM and LTE– High out-of-band emissions– Tight synchronization requirements in LTE– High PAPR

• 5G expected to introduce a new waveform to support
low-latency applications

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Candidate Waveforms• FBMC (Filter band multicarrier)• GFDM (Generalized frequency division multiplexing)– A variant of DFT-precoded-OFDM (SC-FDMA)– Allows self-interference between users for increasing spectrum
efficiency– Low PAPR compared to OFDM
– Low OBB
– Short TTI (transmission time interval): low latency• Need to develop GFDM like waveforms with very low
PAPR and OBB– Other alternatives being investigated at IITH
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Other activities

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Other activities• Cognitive Radio– TV whitespaces• Massive MIMO and millimetre waves– Massive MIMO in LTE– Massive MIMO in mm waves• IoT chipset design24Telecommunications Standards
Development Society, India (TSDSI)

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TSDSI• Indian SDO backed by Govt of India• Responsibilities include: Development oftechnical specifications, advise Govt on policy
and regulation, liaison with external SDOs
• Members include telecom operators, vendors,academia, Govt bodies• Operational for over a year
• IITH contributions active contributor TSDSI
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Summary• IITH to contribute to research, prototype
development, and standardization in 5G– Emphasis on IPR and product development• IITH to develop a smart city prototype at thenew campus– Wireless sensor networks– Smart grid27

Thank you!

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