LTE_A_Telecoma_new.pptx

Copyright © TELCOMA. All Rights Reserved
LTE Advanced and
LTE-Advanced Pro
TELCOMA
The Complete Course

Content:
1. Brief history about LTE.
• What is LTE (Long Term Evolution) ?
• How has LTE Evolved ?
• Driving factors for new LTE enhancements
• 3GPP LTE Releases – 8,9,10,11,12,13,14
2. Network architecture in LTE
• Radio Access network (RAN) – OFDMA and SC-FDMA
• Evolved Packet Core (EPC)

Content contd:
3. LTE Advanced –
• Design requirements for LTE Releases 10-12
• New features –
• Carrier Aggregation
• Coordinated multi-point (COMP) – Uplink and Downlink.
• Single – user and multi-user MIMO
• Enhanced ICIC

Content contd:
4. LTE Advanced Pro–
• Design requirements for LTE Releases 13-14
• New features –
• Advanced Carrier Aggregation
• License Assisted Access – LAA

Brief history about LTE

1980s
1G
• Analog
• AMPS
• Voice
1990s
2G
• Digital
• GSM, IS-95, IS-136
• Voice capacity
2000s
3G
• WCDMA, CDMA2000
• Voice & data
2010s
4G
• LTE/LTE-A, 802.16m
• Broadband data
& video
2020s
5G
Time
Speed/
Throughput
Mbps

Comparison of Wireless technologies
Generation 1G 2G 3G 4G 5G
Deployment 1970-84 1980-89 1990-2002 2000-18 2020+
Throughput 2Kbps 14-64 Kbps 2 Mbps 200 Mbps 1Gbps+
Services Analog Voice Digital Voice
SMS,MMS
Integrated HD
Video and
data
High Speed
Data, Voice
over LTE
(VoLTE)
Ultra-low
Latency,
massive
IoT,V2V
Underlying
Technology
std.
AMPS,TACS D-AMPS,CDMA
(IS-95)
CDMA2000,E
VDO,W-
CDMA,HSPA
+
LTE, VoLTE,
LTE Advanced,
LTE Advanced
Pro
5G-NR

How is LTE different from the
previous technologies ?

How is LTE different ?
LTE benefits (Compared to 3G) include :
• High Data rates
• Reduced Latency
• Improved end-user throughputs for applications such as a Voice and Video
• Flexibility of radio frequency deployment since LTE can be deployed in various
bandwidth configurations (1.4, 3, 5, 10, 15, 20 MHz)
• Multiple Input Multiple Output (MIMO)
• Flat all-IP network with fewer network elements which leads to lower latency.
• Offers a TDD solution (LTE-TDD) in addition to FDD (LTE-FDD)

Why do we need “evolution” in LTE ?
• Past few years have witnessed a rapid growth in number of wireless subscribers and traffic
patterns for users have evolved with explosion of video traffic and emergence of new use-
cases for LTE, such as V2X, MTC etc.
• There have been several advances in cellular communication technologies which have
resulted in increased spectral efficiency. LTE must evolve to take advantage of these
advancements. Examples of these advances include – higher order MIMO, increased
computation power of network equipment (RAN, Core and UEs).

IMT-Advanced Guidelines and Requirements
The key features of IMT-Advanced systems can be summarized as follows :
● Enhanced cell and peak spectral efficiencies, and cell-edge user throughput to
support advanced services and applications
● Lower air-link access and signaling latencies to support delay-sensitive applications
● Support of higher user mobility while maintaining session connectivity
● Efficient utilization of spectrum
● Inter-technology interoperability, allowing worldwide roaming capability
● Enhanced air-interface-agnostic applications and services
● Lower system complexity and implementation cost
● Convergence of fixed and mobile networks
● Capability of interworking with other radio access systems

For a BW of 20 MHz the peak DL
throughput should be 20x15=300
Mbps (Megabits per sec.)

Evolution in LTE
*Source – 3GPP
3GPP Rel. 13,14

4G, LTE and LTE-A Drivers

Network Architecture in LTE

Network Architecture in LTE:
LTE architecture is composed of 2
parts –
• Radio Access Network: Evolved
UTRA Network (E-UTRAN)
• Core Network Architecture : Evolved
Packet Core (EPC)
Evolved Packet
Core (EPC)
Radio Access
Network (RAN
a.k.a E-UTRAN)

Network Architecture in LTE contd:

Network Architecture in LTE contd.
EUTRAN:
Evolved NodeB (eNodeB)
• Radio Resource management
• Synchronization and Interference control
• MME Selection among MME Pool
• Routing of User Plane data from/to S-GW
• Encryption/Integrity protection of user
data
• IP Header Compression

Radio Access Network (RAN)
UE
eNodeB
LTE Downlink
OFDMA
High Spectral Efficiency
Robust against Multipath
Support for MIMO
Time and frequency allocation

RAN
UE
eNodeB
SC-FDMA
Reduced Peak-to-
average Power Ratio Better Cell-edge performance due
to low PAPR
LTE Uplink

OFDMA
• Several multiple access techniques
exist – TDMA, FDMA, CDMA, OFDMA
• OFDMA is not new and has existed for
quite some time.
• The idea is to divide entire bandwidth
into chunks called subcarriers. These
subcarriers can then be allocate in time
and frequency domain.
• Subcarriers are orthogonal in nature.

OFDMA Contd.

OFDMA Contd.
• In LTE transmission happens every 1 msec a.k.a TTI (transmit time interval)
• Concepts –
• Slot
• Symbol
• Sub frame
• Radio Frame

Network Architecture in LTE contd.
EPC:
Mobility Management Entity (MME)
• NAS (non-access stratum) signaling and
its security
• Tracking Areas List management
• PDN GW and SGW selection.
• Roaming and Authentication
• EPS bearer management
• Signaling for mobility management
between 3GPP RANs

Network Architecture in LTE contd:
Each Bearer can have specific QoS
requirements.

LTE-Advanced (Rel.10-12)

LTE Advanced – Design Requirements for Rel
10-12

10-12
3GPP adopted the following guidelines when designing LTE Advanced.
• Peak data rate
• 1Gbps data rate will be achieved by 4x4 MIMO and transmission bandwidth wider than approximately
70 MHz
• Peak spectrum efficiency
• DL: 30 bps/Hz => for a 20 MHz channel BW => 600 Mbps
• UL: 15 bps/Hz => for a 20 MHz channel BW => 300 Mbps

10-12
Capacity and Cell-edge user throughput – Target for LTE-Advanced was set considering gain of 1.4 to
1.6 from Release 8 LTE performance.
https://www.etsi.org/deliver/etsi_tr/13690
0_136999/136913/12.00.00_60/tr_13691
3v120000p.pdf
https://www.itu.int/dms_pub/itu-
r/opb/rep/R-REP-M.2135-1-2009-
PDF-E.pdf

10-12
Spectrum flexibility – Actual available spectra are different according to each region/country.
Therefore additional frequency bands need to be supported.

10-12
- LTE-Advanced will be deployed as an evolution of LTE Release 8
- LTE-Advanced shall be backwards compatible with Rel8. in the sense that –
- A LTE Rel 8. UE can work in a LTE-Advanced NW
- A LTE-advanced terminal can work in a Rel 8. NW
- Increased deployment of indoor eNB in LTE-Advanced.
- How do we achieve these –
- Carrier Aggregation
- COMP
- Interference Coordination
- MIMO advancements

Carrier Aggregation (CA)

LTE Advanced – Carrier Aggregation (CA)
- LTE Releases 8/9 specified system bandwidths of 1.4, 3, 5, 10, 15 and 20 MHz to meet different spectrum
and deployment requirements.
- Support for Higher bandwidth LTE deployments was one of the top goals for IMT-Advanced.
- Carrier Aggregation involves using multiple LTE carriers in conjunction to deliver faster peak throughputs
(uplink and downlink)
- CA was first introduced in LTE Release 10.
- Up to 100 MHz of LTE carrier bandwidth was supported in Rel 10. This translates to (5) 20 MHz LTE
carriers.
- As expected implementation of CA posed many challenges to both vendors and network operators –
Load balancing between LTE Carriers
Filter Design on UE front-ends
Varying RF characteristics between LTE carriers belonging to different LTE Bands.

- In LTE Advanced each LTE carrier is referred to as a Component Carrier (CC).
- A Component carrier can either be a Primary CC or a secondary CC.
- Each CC can either be uplink, downlink or downlink only. But it can’t be uplink-only for obvious reasons.
- Carrier Aggregation in LTE can be of the following types –

- In cases of CA each UE has a serving cell that provides all necessary control information and functions to
the UE such as NAS, mobility, security and RRC. This serving cell is referred to as the Primary Serving
Cell or abbreviated as PCell.
- Each of the additional Cells for the new CC are referred to as Scells or Secondary Cells. There can be
more than one Scells. However, there can only be one Pcell.

- Pcell (Primary Serving Cell) – handles the RRC connection establishment/re-establishment.
- PCC (Primary Component Carrier) – Uplink and Downlink CCs corresponding to Pcell.
- Scell (Secondary Serving Cell) – configured after connection establishment, to provide additional
resources.
- SCC (Secondary Component Carrier) – Uplink and Downlink CCs corresponding to Scell.
- Pcell:
- PDCCH/PDSCH/PUSCH/PUCCH can be transmitted.
- Measurement and mobility procedures are based on Pcell.
- Random access procedure is performed over Pcell
- Can not be deactivated
- DL Pcell and UL Pcell are linked via SIB2
- Scell:
- PDCCH/PDSCH/PUSCH can be transmitted (not PUCCH)
- MAC Layer activation and deactivation is performed.
- Can be cross scheduled

LTE Advanced – Cross Scheduling (CS)
• Cross Scheduling was primarily developed to support heterogeneous networks comprising a combination
of macro-eNBs and low-power nodes (e.g., pico cell, femto-cell, and RRHs) where siginificant inter-cell
interference may arise when those networks are deployed on same frequency.
• Since PDCCH is transmitted across the entire bandwidth of the respective carrier, interference
coordination methods based on fractional re-use may not be adequate to prevent interference.
• With cross scheduling only one component carrier needs to be protected and it can used to allocate
resources on other CCs, thereby reducing interference.

Below are some of the deployment Scenarios for CA.
Scenario – 1
- Operator deploys 2 Frequency carriers
Fc1 and Fc2
- Coverage of Fc1 is similar to coverage of
Fc2.
- This scenario will deliver higher throughputs
across the coverage area.

Scenario – 2
Fc1 and Fc2
- Coverage of Fc1 is NOT similar to coverage of
Fc2. Coverage of Fc1 > Coverage of Fc2
- This scenario will deliver higher throughputs in areas where Fc1 and Fc2 overlap only.
Fc1 is used a mobility layer.

Scenario – 3
Fc1 and Fc2
- Fc1 and Fc2 have different antenna orientations.
-
- Fc1 covers coverage gaps of Fc2 and vice versa

Scenario – 4
Fc1 and Fc2
- Fc1 and Fc2 have different antenna orientations.
Fc2 is only deployed in traffic hotspots on small cells.
Fc1 is used a mobility layer.

LTE Advanced – Carrier Aggregation (CA) – UE
Capabilities.

COMP

Coordinated Multipoint (COMP):
• With the emergence of heterogeneous networks (hetnets) the need for
Interference management has increased substantially.
• Hetnets aim to improve the spectral efficiency of networks by delivering
faster throughputs.
• Unlike homogenous networks the cell sizes vary with hetnets.
• Cell Edge Users are impacted by interference the most due to lack of
dominant serving cells.
• COMP aims to minimize interference for users by enabling coordination of
transmission and/or reception of signals to and/or from the UE.
• COMP can either be implemented in Uplink, downlink or both.

• 3GPP has proposed 4
scenarios for implementing
COMP.
• Scenarios are shown in
the picture.
• First 2 scenarios focus on Homogenous
network deployment, ones with a single
eNodeB Serving multiple sectors (Scenario 1)
and second with multiple high Transmit
eNodeBs (Scenario 2)
• Remaining 2 scenarios target Hetnets

Cooperating Set - The CoMP Cooperating Set is determined by higher layers. It is a set of geographically
separated distribution points that are directly or indirectly involved in data transmission to a device in a
time-frequency resource. Within a cooperating set, there are CoMP points.
In terms of CoMP technique (see below), this could be multiple points at each subframe
(e.g. Joint Transmission) or a single point at each subframe (e.g. Coordinated Scheduling / Beam forming).
Measurement Set - The CoMP Measurement Set is a set of points, about which channel state information
(CSI) or statistical data related to their link to the mobile device is measured and / or reported.
This set is well determined by higher layers. A mobile device, is enabled to down-select the points for which
the actual feedback is reported.

• Measurement Set
• Cooperating Set

Downlink Coordinated Multipoint (DL -
COMP):
• COMP can be implemented in DL or UL
• Each of the these implementations is meant to reduce interference.

Uplink Coordinated Multipoint (UL-COMP):

Interference Coordination

• With the increased deployment of Hetnets (Heterogeneous networks) interference coordination and
possible mitigation strategies need to be deployed to ensure increase network spectral efficiency and
better customer experience.
• Several strategies are possible for minimizing interference (i.e., resource partitioning). Namely they can
be broadly based on the following domains –
• Frequency
• Time
• Spatial
• Combination of Frequency, time and spatial
• Time domain coordination can better adapt to user distribution and network load condition variations, is
the most attractive method for spectrum constrained environments. For example – a macro base station
can choose to reserve some of the sub frames in each radio frame for use by pico base stations, based
on the number of users served by pico base stations.
• Frequency domain coordination can be useful in asynchronous scenarios where macro and pico base
stations use separate blocks of spectrum.
• Spatial Coordination can be achieved by some of the COMP methods – Joint reception/transmission,
beam-forming etc.

• ICIC (Inter-Cell Interference Coordination) has been proposed in LTE Rel 8 for both uplink and downlink.
• Information exchange between nodes is done via means of messages over X2 interface. Messages can
be triggered either by time or events. Examples –
• High Interference Indicator (HII) – enbs can exchange a bitmap for spectrum allocation (resource
blocks) for cell edge users. The bit map essentially represents the USED/FREE status of a resource
block. The neighboring enb can use this information for scheduling its users, and can avoid the USED
resource blocks. This will minimize interference at the Cell edge for users.
• Relative Narrowband transmit power (RNTP) – enbs can exchange a bit map showing relative transmit
power per resource block. The power level on a RB is compared to a pre-defined threshold value.
Enbs can use this information for scheduling purposes and possible avoid using RBs which are being
transmitted by other enbs at power > threshold.
• Overload Indicator (OI) – Enbs can exchange information re Uplink noise/interference levels
(high/low/medium). The receiving enb can then try to minimize UE Tx power for its users, thereby
reducing interference.

Enhanced

Enhanced Interference Coordination
• 3GPP wanted to enhance the previous ICIC strategies further, so they proposed eICIC (Enhanced Inter-
Cell Interference Coordination).
• There are 2 possible approaches for eICIC –
• CA based ICIC
• Non-CA based ICIC
• CA based eICIC relies on interference coordination/mitigation by means of CA and RNTP (relative
narrowband transmit power). Details to follow.
• Non-CA based ICIC relies on interference coordination/mitigation by means of time-domain ABS (almost
blank Sub frames). Details to follow.

CA-based eICIC
• The idea behind CA-based eICIC is to create a protective component carrier in HetNet deployments. This
protected carrier is then used to reliably deliver critical downlink and uplink information – reference
signals, scheduling assignments, paging etc.
• Imagine a scenario where we have 1 macro enb and 1 Pico node. Each of these nodes has 2 CC’s – CC1
and CC2. CC1 is the protect carrier so the macro enb restricts its TX power on CC1 to allow for pico node
to also operate on CC1. CC2 on the other hand is not a protected carrier, therefore the macro enb
transmits on CC2 at its nominal output power. Macro enb communicates the RNTP information to the pico
node, therefore pico restricts its power on CC2.

CA-based eICIC

Non-CA eICIC
• ABS – Almost Blank Sub frames

MIMO

MIMO in LTE
• MIMO (Multiple input and multiple output) is a key part of LTE deployments. LTE standard is based on a
combination of MIMO multi-antenna techniques and OFDM multicarrier techniques.
• The relationship between the received and transmitted signals on different antennas is expressed by a
system of linear equations. In this system, the vector of received signals is expressed as a product of
channel matrix (H) and the transmitted signal.

MIMO in LTE
• Transmission matrix H contains the channel impulse responses h{n,m}, which reference the channel
between the transmit antenna m and the receive antenna n. Rank of the transmission matrix H defines
the number of independent data streams that can be transmitted simultaneously.

MIMO in LTE
• Transmit diversity – Increasing the robustness of data transmission. In this case the same data is
transmitted redundantly over more than one transmit antenna. This increases the signal to noise ratio at
the receiver. Space-time codes are used to generate a redundant signal.
• Spatial Multiplexing – Increasing the data rate. In this case data is divided in separate streams, which are
then transmitted simultaneously over the same air interface resources. The transmission includes special
signals called reference signals, which are known to the RX. This helps the RX in channel estimation.
Spatial MUX can either be closed loop or open loop.
• Further Spatial MUX can be either single User or multi-user. In single user scenario, the data rate is
increased for a single UE. When individual streams are assigned to multiple UE’s at the same time it is
called multi-user MIMO.

SU-MIMO in LTE

MU-MIMO in LTE

LTE-Advanced Pro (Rel.13-14)

13-14

13-14
- Data Speeds in excess of 3Gbps (LTE-A: 1 Gpbs)
- Support for Carrier bandwidth of 640 MHz (LTE-A: 100 MHz)
- Latency: 2 msec (LTE-A: 10 msec)
How does LTE-AP achieve these
goals ?
License Assisted Access (LAA), Advanced Carrier Agg, dual
connectivity, beam forming

LTE Advanced Pro

Advanced CA

LTE Advanced Pro – Advanced Carrier Agg.

LAA

LTE Advanced Pro – License Assisted Access
Spectrum is not an infinite resource, and spectrum assets used by already deployed wireless systems
– both commercial and non-commercial – cannot easily be revoked. Regulators worldwide have
therefore started looking into alternatives to use the available spectrum more efficiently while exploring
the concept of shared spectrum. In the meantime, the cellular industry, led by several network
operators, infrastructure vendors and chipset manufacturers, has eyed unlicensed spectrum, particularly
the 5 GHz industrial, scientific and medical (ISM) band, to serve the immediate need for additional
spectrum for mobile broadband applications due to the ever increasing mobile data traffic.
The ISM bands are generally defined by the ITU Radio Regulations (Article 5) [21], but are regulated
differently by each region (e.g. ETSI in Europe or FCC in USA). The exact frequency allocation and
detailed regulation depends on the country (e.g. South Korea vs. Japan).

LTE Advanced Pro – License Assisted Access

eLAA

eLAA
Enhanced licensed assisted access (eLAA) is part of 3GPP Release 14. It defines how user equipment
can access the 5 GHz ISM band to transmit data in the uplink direction. The first major difference to
LAA is that generally all uplink transmissions in LTE are scheduled and therefore under the control of
the serving LTE base station (eNB). Since this affects the channel contention between devices, the
required LBT scheme that was defined in LAA for downlink operation needs to be adapted to work in the
uplink direction.
The second major difference is the regulatory requirements that have to be fulfilled while using the 5
GHz ISM band in certain regions. For example, the European Telecommunication Standardization
Institute (ETSI) mandates that the occupied channel bandwidth, defined by 3GPP to be the bandwidth
containing 99% of the power of the signal, shall be between 80% and 100% of the declared nominal
channel bandwidth. As an initial approach, multi-cluster PUSCH operation, standardized in 3GPP
Release 10, was considered to fulfill this ETSI requirement. Multi-cluster PUSCH allows two clusters of
resource blocks to be scheduled far enough from each other to fulfill e.g. the 80% bandwidth
requirement.

eLAA
Further investigation by 3GPP’s contributing members have shown that multi-
cluster PUSCH is not the most efficient way to address this requirement and
therefore another solution was required.

LTE_A_Telecoma_new.pptx

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