156514180-AIRCOM-Asset-LTE-Basics-and-Asset.pdf

1 © 2012 AIRCOM International Ltd
Section 1: LTE Air-Interface
Instructor – Ishan Marwah

Roadmap
GSM
EDGE
WCDMA
2G 2.5G 3G phase 1
GPRS
Evolved 3G
HSDPA
HSUPA*
2000/2001 2003/2004 2005 2007
LTE
2010

Where are we?
 LTE is now on the market (both radio and core network evolution)
 Release 8 was frozen in December 2008 and this has been the basis
for the first wave of LTE equipment
 Enhancements to LTE were frozen in to release 9 in December 2009

Flat Architecture
Traditional
Architecture
Control plane
User plane
GGSN
SGSN
RNC
NODE B
One Tunnel
Architecture
REL7
GGSN
SGSN
RNC
NODE B
SAE /GW– System
Architecture Evolution
MME - Mobility
Management Entity
eNodeB - evolved Node B
LTE
SAE GW
MME
eNODEB
IP Network
IP Network
IP Network

LTE-UE
Evolved UTRAN (E-UTRAN)
MME
S6a
Serving
Gateway
S1-U
S11
Evolved Packet Core (EPC)
S1-MME
PDN
Gateway
IMS
PCRF
S7
S5
Evolved
Node B
(eNB)
X2
LTE-Uu
HSS
MME: Mobility Management Entity
Policy & Charging
Rule Function
LTE Network Architecture

Release 8– LTE – New Air interface
The LTE DOWNLINK uses OFDMA
 Orthogonal Frequency Division Multiple Access
 This new OFDMA based air interface is also often referred to as the
 Evolved UMTS Terrestrial Radio Access Network (EUTRAN)
 300 Mbit/s per 20 MHz of spectrum
Uplink
 uses Single Carrier Frequency Division Multiple Access (SC-FDMA)
 Single Carrier Frequency means information is modulated only to one
carrier, adjusting the phase or amplitude of the carrier or both
 75 Mbit/s per 20 MHz of spectrum
OFDMA
SC-FDMA
eNODE B

The Physical Layer - OFDM and OFDMA
Orthogonal
Frequency
Division
Multiplexing
Each user is
assigned a
specific
frequency
resource
Orthogonal
Frequency
Division
Multiple
Access
Each user is
assigned a
specific time-
frequency
resource

Multiple Access DL
LTE employs OFDM as the basic modulation scheme and multiple access is achieved through:
• OFDMA in the LTE Downlink
• A multi-carrier signal with one data symbol per subcarrier
• Scalable to wider bandwidths, multipath resilient and better suited for MIMO architecture
• Drawback: Parallel transmission of multiple symbols creates undesirable high PAPR

Multiple Access UL
SC-OFDMA in the LTE Uplink
• SC-FDMA transmits the four QPSK data symbols from a user in series at four times the rate, with
each data symbol occupying N x 15 kHz bandwidth.
• Signal more like single carrier with each data symbol being represented by one wide symbol
• Occupied bandwidth same as OFDMA but crucially, the PAPR is the same as that used for original
data symbol

Advanced Antenna Techniques
• MIMO needs a high signal-to-noise ratio (SNR) at the UE
• High SNR ensures that the UE is able to decode the incoming signal
• This ensures good orthogonality
Use multiple channels to send
multiple information streams
(spatial multiplexing)
• Increase throughput
MIMO creates multiple parallel
channels between transmitter and
receiver. MIMO is using time and space
to transmit data (space time coding).

LTE - FDD/TDD
There are two types of LTE frame structure:
 Type 1: used for the LTE FDD mode systems.
 Type 2: used for the LTE TDD systems.
 LTE can be used in both paired (FDD) and unpaired (TDD)
spectrum.
 FDD & TDD supports bandwidths from 1.4 Mhz to 20Mhz
FDD
F -DL
F -UL
TDD

FDD
 Type 1 used for the LTE FDD mode systems.
 The basic type 1 LTE frame has an overall length of 10
ms. This is then divided into a total of 20 individual
slots. LTE Subframes then consist of two slots - in other
words there are ten LTE subframes within a frame.
0 1 2 3 19
One Sub-
frame = 1 mS
10 ms

TDD
Type 2 LTE Frame Structure
 The frame structure for the type 2 frames used on LTE TDD is
somewhat different. The 10 ms frame comprises two half frames,
each 5 ms long. The LTE half-frames are further split into five
subframes, each 1ms long.
10 ms
0 2 3 4 0 1 2 3 4

TDD
The special subframes consist of the three fields:
 DwPTS (Downlink Pilot Timeslot)
 GP (Guard Period)
 UpPTS (Uplink Pilot Timeslot)
One radio frame Tf =10 ms
One half- frame Thf = 5 ms
Sub-frame
#0
Sub-frame
#2
Sub-frame
#3
Sub-frame
#4
DwPTS
GP
UpPTS
Sub-frame
#5
Sub-frame
#7
Sub-frame
#8
Sub-frame
#9
DwPTS
GP
UpPTS
special sub-fames

TDD
 A total of seven up / downlink
configurations have been set,
and these use either 5 ms or 10
ms switch periodicities.
 “S” denotes the special subframe
when you go from DL to U
 The special subframes consist of the
three fields: DwPTS (Downlink Pilot
Timeslot), GP (Guard Period), and
UpPTS (Uplink Pilot Timeslot)
0 1 2 3 19
10 ms

Flexible Carrier Bandwidths
 LTE is defined to
support flexible carrier
bandwidths from
1.4MHz up to 20MHz,
in many spectrum
bands and for both
FDD and TDD
deployments
 Supported LTE modes
of operation:
 Frequency Division
Duplex (FDD)
 Time Division
Duplex (TDD)

Supported Channels (non-overlapping)
E-UTRA
Band
Downlink
Bandwidth
Channel Bandwidth (MHZ)
1.4 3 5 10 15 20
1 60 - - 12 6 4 3
2 60 42 20 12 6 4* 3*
3 75 53 23 15 7 5* 3*
4 45 32 15 9 4 3 2
5 25 17 8 5 2* - -
6 10 - - 2 1* X X
7 70 - - 14 7 4 3*
8 35 25 11 7 3* - -
9 35 - - 7 3 2* 1*
10 60 - - 12 6 4 3
11 25 - - 5 2* 1* 1*
12 18 12 6 3* 1* - X
13 10 7 3 2* 1* X X
14 10 7 3 2* 1* X X
...
33 20 - - 4 2 1 1
34 15 - - 3 1 1 X
35 60 42 20 12 6 4 3
36 60 42 20 12 6 4 3
37 20 - - 4 2 1 1
38 50 - - 10 5 - -
39 40 - - 8 4 3 2
40 100 - - - 10 6 5
* UE receiver sensitivity can be relaxed
X Channel bandwidth too wide for the band
- Not supported
E-UTRA Bands and Channel Bandwidths
 E-UTRA bands are regulated to allow
operations in only certain set of Channel
Bandwidths which are defined as
 The RF bandwidth supporting a
single E-UTRA RF carrier with the
transmission bandwidth configured
in the uplink or downlink of a cell
 Channel bandwidth is measured in MHz
and is used as a reference for
transmitter and receiver RF requirements
 Some EUTRA bands do not allow
operation in the narrow bandwidth
modes , i.e. < 5 MHz
 Others restrict operations in the wider
channel bandwidths, i.e. > 15 MHz

LTE Bands

Comparison FDD/TDD
1. FDD LTE uses frequency division, while TDD LTE uses
time division
2. FDD LTE is full duplex, while TDD LTE is half duplex
3. FDD LTE is better for symmetric traffic, while TDD is
better for asymmetric traffic
4. FDD LTE allows for easier planning than TDD LTE
FDD base stations use different frequencies for receiving and transmitting,
they effectively do not hear each other and no special planning is needed.
With TDD, special considerations need to be taken in order to prevent
neighbouring base stations from interfering with each other

Sub-Carriers
15Khz Spacing saving
bandwidth. 12 carriers
for 0.5ms
7.5Khz Spacing saving
bandwidth. 24
subcarriers for 0.5 ms.
200Khz
GSM
LTE
b0 b1
QPSK
Im
Re
10
11
00
01
b0 b1b2b3
16QAM
Im
Re
0000
1111
Im
Re
64QAM
b0 b1b2b3 b4 b5

Slot Structure and Physical Resources
 ONE slot = 12 consecutive
subcarriers
 One slot = 0.5mS
 6 or 7 OFDM symbols
(depending upon cyclic perfix
size), thus a single resource
block is containing either 72
or 84 OFDM symbols
 12x 7 = 84 OFDM symbols

b0 b1
QPSK
Im
Re
10
11
00
01
b0 b1b2b3
16QAM
Im
Re
0000
1111
Im
Re
64QAM
b0 b1b2b3 b4 b5
One Slot = 0.5mS

R
B
R
B
R
B
R
B
R
B
R
B
R
B
R
B
R
B
R
B
R
B
R
B
R
B
BW config
BW Channel
CHANNEL
BW (Mhz)
Nrb BW config=
Nrb x 12 x15
1000
% of
Channel
BW
1.4 6 1.08 77%
3 15 2.7 90%
5 25 4.5 90%
10 50 9 90%
15 75 13.5 90%
20 100 18.0 90%
Channel BW

Bandwidth
(MHz)
1.4 3 5 10 15 20
# of RBs 6 15 25 50 75 100
Subcarriers 72 180 300 600 900 1200

Cyclic Prefix
 In the time domain, a guard interval may be added to each symbol to combat
inter-OFDM-symbol-interference due to channel delay spread
 The guard interval is a cyclic prefix which is inserted prior to each OFDM symbol
One Slot = 0.5ms
One sub Frame=1mS
7 OFDM Symbols
All Data
7 OFDM Symbols
cyclic prefix
The length of the cyclic prefix, CP is important. If it is not long enough then it
will not counteract the multipath reflection delay spread. If it is too long, then it
will reduce the data throughput capacity.

Direct signal
Reflection 1
Last Reflection
Guard
Period
Sampling Window
2
Time Domain
1
3
Normal
For LTE, the standard
length of the cyclic
prefix has been
chosen to be 4.69 µs.
This enables the
system to
accommodate path
variations of up to 1.4
km. With the symbol
length in LTE set to
66.7 µs
Delay Spread

Cyclic Prefix
 To each OFDM symbol, a cyclic prefix (CP) is appended as guard time
 One downlink slot consists of 6 or 7 OFDM symbols, depending on whether extended
or normal cyclic prefix is configured, respectively
 The extended cyclic prefix is able to cover larger cell sizes with higher delay
spread of the radio channel

Each 1ms Transmission
Time Interval (TTI)
consists of two slots
(Tslot)

OFDMA and Throughputs
15kHz
To symbol rate of 1/15KHz = 66.7us
Therefore 15 Kilosymbols per second
For 20Mhz bandwidth (1200 carriers)
symbol rate = 1200 x 15= 18Msps
Each symbol using 64 QAM (6 bits)
Total peak rate =
18 Msps x 6 bits = 108Mbps
Subtract overhead and coding and add
gains (MIMO)
66.7us
Each symbol
2 bits(QPSK), 4 Bits (16 QAM)
and 6 bits 64 QAM

Downlink Reference Signal Structure
PDSCH
Downlink reference signal
RSRP (Reference Signal Received Power)
RSRP is a RSSI type of measurement. It measures the average received
power over the resource elements that carry cell-specific reference
signals within certain frequency bandwidth.
RSRP is applicable in both RRC_idle and RRC_connected modes
Downlink reference
signal structure
The downlink reference
signal structure is
important for channel
estimation.
The principle of the
downlink reference signal
structure for 1 antenna.
Ref Signal TX1= 8 for
15Khz spacing

Configuration of Carrier
 Note that when multiple antennas are used for transmission, then
there is a resource grid for each one.
 EUTRAN support 1, 2 or 4 antennas, called the antenna ports
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
R0
Port 1
Port 4
Port 3
Port 2

Configuration of Carrier - 1 Antenna
Carrier 1
Overhead REF, Control, Broadcast, Syn
Downlink Reference
Signal Structure
signal structure is
estimation.
Ref Signal TX1 = 8 for
15Khz spacing
R0
R0
R0 R0
R0
R0
R0
R0
Specific pre-defined resource elements (indicated
by R0-3 in in the time-frequency domain are
carrying the cell-specific reference signal
sequence.

Carrier 1
Downlink Reference
Signal Structure
signal structure is
estimation.
downlink reference
signal structure for 2
antenna.
15Khz spacing
R0
R0
R0 R0
R0
R0
R0
R0
R1 R1
R1
R1 R1
R1 R1
R1
Specific pre-defined resource elements (indicated by
R0-3 in in the time-frequency domain are carrying
the cell-specific reference signal sequence.

Carrier 1
Downlink Reference
Signal Structure
signal structure is
estimation.
15Khz spacing
R0
R0
R0 R0
R0
R0
R0
R0
R1 R1
R1
R1 R1
R1 R1
R1
R2
R2
R2
R2
Specific pre-defined resource elements (indicated by
R0-3 in in the time-frequency domain are carrying
the cell-specific reference signal sequence.

Carrier 1
Downlink reference
signal structure
signal structure is
estimation.
15Khz spacing
R0
R0
R0 R0
R0
R0
R0
R0
R1 R1
R1
R1 R1
R1 R1
R1
R2
R2
R2
R2
R3
R3
R3
R3
Specific pre-defined resource elements (indicated
by R0-3 in in the time-frequency domain are
carrying the cell-specific reference signal
sequence.

Type1-DL Frame

FDD Frame Structures UL
Type1-FDD- Uplink
UL Control Channel
• PUCCH transmission in one subframe is compromised of single
PRB at or near one edge of the system bandwidth followed by a
second PRB at or near the opposite edge of the bandwidth
• PUCCH regions depends on the system bandwidth. Typical values
are 1, 2, 4, 8 and 16 for 1.4, 3, 5, 10 and 20 MHz
UL Signals(S-RS & DM RS)
• S-RS estimates the channel quality required for the UL
frequency-selective scheduling and transmitted on 1 symbol in
each subframe
• DM-RS is associated with the transmission of UL data on the
PUSCH andor control signalling on the PUCCH
• mainly used for channel estimation for coherent
demodulation
• transmitted on 2 symbols in each subframe

Type1- UL Frame

RSRQ is defined as the ratio N×RSRP / (E-UTRA carrier RSSI)
RSRP is applicable RRC connected modes
LTE_ACTIVE state
RSRQ (Reference Signal Received Quality)
 In LTE network, a UE measures:
 RSRQ (Reference Signal Received Quality)

Frequency Band Considerations
 Fifteen FDD band options and eight TDD band
 The specific spectrum availability will depend on the country and region in
which the network will operate.
 An operator may already have licensed spectrum available in which LTE
could be rolled out. This may be because an older legacy technology can
be progressively switched off, or because they have spectrum that is
currently unused
 Given the possible expense of purchasing new radio licences, most
operators will at least consider the possibility of refarming their existing
licensed spectrum for LTE use.
 In most cases, however, an operator will need to consider purchasing new
spectrum in which to operate LTE. Even when new spectrum is available,
an operator will need to consider a number of configuration options.

Propagation (Path Loss) Models
A propagation model describes the average
signal propagation, and it converts the maximum
allowed propagation loss to the maximum cell range.
It depends on:
• Environment : urban, rural, dense urban, suburban,
open, forest, sea…
• Frequency
• atmospheric conditions
• Indoor/outdoor

Free Space Path Loss
 For typical radio applications, it is common to find measured in
units of MHz and in km, in which case the FSPL equation becomes:
 Free-Space Path Loss (FSPL) is the loss in signal strength of an
electromagnetic wave that would result from a line-of-site path
through free space, with no obstacles nearby to cause reflection or
diffraction.
FSPL= 32.5 + 20 log10(d) + 20 log10(f) dBm

Free Space Path Loss Formula at 1800Mhz
 Lo = 32.5 + 20 log(d) + 20 log(fMhz) dBm
What is the free space
path loss at:
1800Mhz at 1Km
20 log (1) + 20logx1800
=0 +65
=32.5 + 65 dB
=97.5
path loss at:
1800Mhz at 10Km
20 log (10) + 20log1800
=20 +65
=32.5+85dB
=117.5
path loss at:
1800Mhz at 100Km
20 log (100) + 20log10x1800
=40 +65
=32.5+105dB
=137
20dB different

Free Space Path Loss Formula at 900Mhz:
 Lo = 32.5 + 20 log10(d) + 20 log10(fMhz) dBm
path loss at:
900Mhz at 1Km
20 log (1) + 20log x 900
=0 + 59
=32.5 + 59dB
=91.5dB
path loss at:
900Mhz at 10Km
20 log (10) + 20log x 900
=20 +59
=32.5+79dB
=111.5dB
path loss at:
900Mhz at 100Km
20 log (100) + 20log10x900
=40 +59
=32.5+99dB
=131.5
20dB different

Examples
path loss at:
1800Mhz at 1Km
20 log (1) + 20logx1800
=0 +65
=32.5 + 65 dB
=97.5
path loss at:
1800Mhz at 10Km
20 log (10) + 20log1800
=20 +65
=32.5+85dB
=117.5
path loss at:
1800Mhz at 100Km
20 log (100) + 20log10x1800
=40 +65
=32.5+105dB
=137
path loss at:
900Mhz at 1Km
20 log (1) + 20log x 900
=0 + 59
=32.5 + 59dB
=91.5dB
path loss at:
900Mhz at 10Km
20 log (10) + 20log x 900
=20 +59
=32.5+79dB
=111.5dB
path loss at:
900Mhz at 100Km
20 log (100) + 20log10x900
=40 +59
=32.5+99dB
=131.5

 The frequency ranges covered by the
defined operating bands for LTE vary
greatly and include bands based around
700 MHz up to bands around 2.6 GHz.
 The band makes a significant difference
to the number of sites required for
network rollout.
 11.4 dB difference in free space path
loss between 700 MHz and 2.6 GHz.
700
MHz
At 700 MHz could be between three and
four times larger than at 2.6 GHz.
2.6 GHz

700 MHz
• In the U.S. this commercial spectrum is scheduled to be auctioned in
January 2008
• This includes 62 MHz of spectrum broken into 4 blocks:
• A (12 MHz)
• B (12 MHz)
• E (6 MHz unpaired)
• C (22 MHz)
• D (10 MHz)
• These bands are highly prized chunks of spectrum and a tremendous
resource: the low frequency is efficient and will allow for a network that
doesn’t require a dense build out and provides better in-building penetration
than higher frequency bands.

Refarming GSM 900 MHz
 900MHz offers improved building penetration and is particularly well suited to
supporting those regions that have a predominantly rural population.
 The ongoing subscriber migration from GSM to UMTS taking place in over 150
countries worldwide is relieving pressure on the GSM900 networks and is
starting to free up some spectrum capacity in that band.
 Deploying LTE in 900MHz can also bring the additional cost and logistic
benefits of being able to deploy LTE at existing GSM sites as the coverage of
GSM/LTE in 900MHz should be very similar.
 Compared to HSDPA/HSDPA+, LTE is expected to substantially improve end-
user throughputs, sector capacity and reduce user plane latency to deliver a
significantly improved user experience. As such, the industry expects that
Service Providers will wait to deploy LTE in the refarmed 900 MHz

Frequency Planning
 How much spectrum an operator may have access to. Historically, radio
licences for 20 MHz,either TDD or FDD, have been rare.
 Much more common would be 10–15 MHz. Additionally, it must be borne
in mind that in most implementations some form of frequency plan must
be used.
 For example, an operator with a licence for 15 MHz may need to
implement this as three 5 MHz channels.
 It is possible to implement LTE as an SFN (Single Frequency Network),
but the high level of interference at cell edges reduces the available
bandwidth unless Interference Management Systems are used.

Questions

Questions
1. What is the maximum bit rate if you assign a
bandwidth of 10Mhz to a sector and a UE is allocated
all RB?

Questions
all RB?

Questions
4. What is meant by Normal type1?
5. Compare band 13 to band 1?
6. What is meant by GSM re-farming?

Session 02
Setting up a LTE Network in Asset

Antenna Database
Antenna Information and Mask

Setting up a Propagation Model
Propagation models are
mathematical attempts to
model the real radio
environment as closely as
possible. Most
propagation models need
to be tuned (calibrated)
by being compared to
measured propagation
data, otherwise you will
not be able to obtain
accurate coverage
predictions.

Std. Macrocell Propagation Model
 Asset Standard Macrocell model
loss
Clutter
loss
n
diffractio
K
d
og
l
H
g
lo
K
gH
lo
K
ogH
l
K
H
K
d
og
l
K
K
PL
eff
eff
ms
ms
)
(
7
)
(
)
(
6
5
4
3
)
(
2
1

Recommended Starting Parameters
K values 450 MHz 900 MHz 1800 MHz 2000 MHz 2500 MHz 3500 MHz
k1 for LOS 142.3 150.6 160.9 162.5 164.1 167
k2 for LOS 44.9 44.9 44.9 44.9 44.9 44.9
k1 (near) for
LOS
129.00 0.00 0.00 0.00 0.00 0.00
k2 (near) for
LOS
31.00 0.00 0.00 0.00 0.00 0.00
d < for LOS 0.00 0.00 0.00 0.00 0.00 0.00
k1 for NLOS 142.3 150.6 160.9 162.5 164.1 167
k2 for NLOS 44.9 44.9 44.9 44.9 44.9 44.9
k1 (near) for
NLOS
129.00 0.00 0.00 0.00 0.00 0.00
k2 (near) for
NLOS
31.00 0.00 0.00 0.00 0.00 0.00
d < for NLOS 0.00 0.00 0.00 0.00 0.00 0.00
k3 -2.22 -2.55 -2.88 -2.93 -3.04 -3.20
k4 -0.8 0.00 0.00 0.00 0.00 0.00
k5 -11.70 -13.82 -13.82 -13.82 -13.82 -13.82
k6 -4.30 -6.55 -6.55 -6.55 -6.55 -6.55
k7 0.4 0.7 0.8 0.8 0.8 0.8

MME and SAE-GW Support
Asset support for hieratically higher LTE network elements
 Mobility Management Entity (MME)
 System Architecture Evolution Gate Way (SAE-GW)
 Support for Logical/Cellular Connections that allow
for the mesh-type parent-child relationships of the
LTE Core.
 eNodeB can be parented to both an SAEGW and
MME and can be parented to multiple SAEGWs
and/or MMEs

MME and SAE-GW Support

LTE Frame Structures

LTE Frequency Bands

LTE Carriers

Interference Co-ordination Schemes
To minimize Intercell Interference following frequency reuse schemes are being
considered
Frequency Reuse-1 with Prioritization
• Each sector divides the available bandwidth into prioritized (one third) and non-
prioritized (two third) sections disregard of CE or CC.
• Prioritized spectrum is used more often than non-prioritized by each sector in order to
concentrate the interference that it causes to other sectors

Interference Co-ordination Schemes
Soft Frequency Reuse
• Power difference between the prioritized and non-prioritized spectrum which divides the
sector into an inner and an outer region
• User in the inner region can be reached with reduced power, i.e. Cell Centre Users (CCU)
than the users in the outer region i.e. Cell Edge Users (CEU)
• CCU are assigned frequency Reuse-1 while CEU employ Reuse-3 with soft reuse

Interference Coordination Schemes
Reuse Partitioning
• Similar to Soft Frequency Reuse
• High-power part is divided between sectors so that each sector gets one third of the high-
power spectrum
• Low-power part employs frequency Reuse-1 while high-power part is configured with a
frequency Reuse-3 with hard reuse.

Interference Coordination Schemes

MIMO - Transmit Diversity
Instead of increasing data rate or capacity, MIMO can be used to exploit
diversity and increase the robustness of data transmission.
Each transmit antenna transmits essentially the same stream of data, so the
receiver gets replicas of the same signal.
T
X
R
X
010100
010100
010100
SU-MIMO

MIMO - Spatial Multiplexing
010
T
X
R
X
010100
100
SU-MIMO
Spatial multiplexing allows an increase in the peak rates by a factor of 2 or 4,
depending on the eNodeB and the UE antenna configuration.
Spatial multiplexing allows to transmit different streams of data, different
reference symbols simultaneously on the same resource blocks

LTE Downlink Transmission Modes
• LTE Rel 8 supports DLtransmission on 1, 2, or 4 antenna ports:
• 1, 2, or 4 cell-specific reference signals
• each reference signal corresponds to one antenna port
• DL transmission modes are defined for PDSCH (DataTraffic)
• Single antenna (No MIMO)
• Transmit diversity
• Open loop Spatial multiplexing
• Closed loop spatial multiplexing
• Multi user MIMO
• Closed-loop precoding for Rank=1 (No spatial Mux, But precode)
• Conventional beamforming
• UL MIMO Modes
• Transmit diversity
• Receive Diversity
• MU-MIMO
SU-MIMO

SU-MIMO
• This includes conventional techniques such as
• Cyclic Delay Diversity
• TransmitReceive diversity (Space frequency block codes)
• Spatial Multiplexing Precoded Spatial Multiplexing
• Can be implemented as Open and Closed loop
• Diversity techniques improves the signal to interference ratio by
transmitting same stream of single user data.
• Spatial multiplexing increases the per user data ratethroughput by
transmitting multiple streams of data dedicated for a single user

MU-MIMO
• Multiple users (separated in the spatial domain in both UL and
DL) sharing the same time-frequency resources
• Uses multiple narrow beams to separate users in the spatial
domain and can be considered as a hybrid of beamforming and
spatial multiplexing.
• Serves more terminals by scheduling multiple terminals using the
same resources
• this increases the cell capacity and number of served
terminals
• Suitable for highly loaded cells and for scenarios where number
of served terminals is more important than peak user data rates

Lookup Table for AAS

Templates for Sites
When planning a network, Instead of setting the parameter values on
each node individually, you can define templates, then select one of
these templates as a basis for adding new nodes. The new nodes will
then contain the default characteristics of the template.

Adding Sites/Cells
 You can add network elements by using the site
design toolbar in the Map View window and also by
using the Site Database window.
 You need the correct privileges to be able to add
and modify network elements. Contact your
administrator if you do not have the correct
permissions

AAS Settings in Site DB

LTE Parameters

Scheduler
Scheduler Description
Round Robin The aim of this Scheduler is to share the available/unused resources equally among the terminals
(that are requesting RT services) in order to satisfy their RT-MBR demand.
This is a recursive algorithm and continues to share resources equally among terminals, until all RT-
MBR demands have been met or there are no more resources left to allocate.
Proportional
Fair
The aim of this Scheduler is to allocate the available/unused resources as fairly as possible in such a
way that, on average, each terminal gets the highest possible throughput achievable under the
channel conditions.
This is a recursive algorithm. The available/unused resources are shared between the RT terminals in
proportion to the bearer data rates of the terminals. Terminals with higher data rates get a larger
share of the available resources. Each terminal gets either the resources it needs to satisfy its RT-
MBR demand, or its weighted portion of the available/unused resources, whichever is smaller. This
recursive allocation process continues until all RT-MBR demands have been met or there are no more
resources left to allocate.
Proportional
Demand
The aim of this Scheduler is to allocate the available/unused resources in proportion to the RT-MBR
demand, which means that terminals with higher RT-MBR demand achieve higher throughputs than
terminals with lower RT-MBR demand. This is a non-recursive resource allocation process and results
in either satisfying the RT-MBR demands of all terminals or the consumption of all of the
available/unused resources.
Max SINR The aim of this Scheduler is to maximise the terminal throughput and in turn the average cell
throughput. This is a non-recursive resource allocation process where terminals with higher bearer
rates (and consequently higher SINR) are preferred over terminals with low bearer rates (and
consequently lower SINR). This means that resources are allocated first to those terminals with better
SINR/channel conditions than others, thereby maximising the throughput.

LTE Parameters
Load (%) Interference
Margin (dB)
35 1
40 1.3
50 1.8
60 2.4
70 2.9
80 3.3
90 3.7
100 4.2

Session 03
Predicting and Displaying Coverage

Predicting Coverage

Best RSRP Coverage Example

Array Display Properties
To customise the arrays displayed in the Map View window, Use the
Show Data Types button.

Coverage Reports/Statistics
Once coverage arrays have been created, you can
generate coverage statistics.

Coverage Reports/Statistics

Array Manager
Array manager enable memory management on arrays and
simulations. In addition, the Array Manager provides the ability to
retrieve archived arrays, allowing for the benchmarking of statistical
changes over time.

Session 04
Traffic Planning on a LTE Network

Default LTE Bearers
Bearers represent the air interface connections, performing the task
of transporting voice and data information between cells and
terminal types.

Channel Quality Indicator Tables
Indicates a combination of modulation and coding scheme that the NodeB
should use to ensure that the BLER experienced by the UE remains <
10%
eNB
UE1
UE2
UE3
UE4
UE5
64 QAM
16 QAM
QPSK
CQI Modulation Efficiency Actual
coding rate
Required
SINR
1 QPSK 0.1523 0.07618 -4.46
2 QPSK 0.2344 0.11719 -3.75
3 QPSK 0.3770 0.18848 -2.55
4 QPSK 0.6016 308/1024 -1.15
5 QPSK 0.8770 449/1024 1.75
6 QPSK 1.1758 602/1024 3.65
7 16QAM 1.4766 378/1024 5.2
8 16QAM 1.9141 490/1024 6.1
9 16QAM 2.4063 616/1024 7.55
10 64QAM 2.7305 466/1024 10.85
11 64QAM 3.3223 567/1024 11.55
12 64QAM 3.9023 666/1024 12.75
13 64QAM 4.5234 772/1024 14.55
14 64QAM 5.1152 873/1024 18.15
15 64QAM 5.5547 948/1024 19.25

LTE Services
The parameters that you specify will influence how the simulation
behaves and will enable you to examine coverage and service
quality for individual types of service.

LTE Services and QoS Parameters
Name QCI Resourc
e
Type
Priorit
y
Packet
Delay
Budget
Packet
Error
Loss Rate
Example Services
VoIP 1 GBR 2 100 ms 10-2 Conversational Voice
Video Call 2 GBR 4 150 ms 10-3
Conversational Video (Live
Streaming)
Gaming 3 GBR 3 50 ms 10-3 Real Time Gaming
Streaming 4 GBR 5 300 ms 10-6
Non-Convers.Video (Buff.
Streaming)
Signalling 5 Non-GBR 1 100 ms 10-6 IMS Signalling
E-mail 6 Non-GBR 6 300 ms 10-6
Video (Buffered Streaming),
TCP-based (www, e-mail, chat,
ftp, p2p sharing, Progressive
video, etc.)
Voice, Video (Live Streaming)
Interactive Gaming
Web
browsing
7 Non-GBR 6 100 ms 10-3
P2P File
Sharing
8 Non-GBR 8 300 ms 10-6
Chat 9 Non-GBR 9 300 ms 10-6

Clutter Parameters
You can define different shadow fading standard deviations for
outdoor terminals and indoor terminals per clutter type. If a
building is in urban, it will encounter greater fading than in
parkland.
You can also specify different indoor losses for each clutter type.

Terminal Types
ASSET models traffic demand by generating traffic density maps for the
different types of terminal. These density maps define the amount of
traffic offered to the network by each type of terminal on a pixel-by-
pixel basis, corresponding to the available clutter map data resolutions.
A Terminal Type in ASSET defines these key characteristics:
 How much ‘traffic’ will the terminal type generate in total?
 How will the ‘traffic’ be spread geographically?
 What is the expected mobile speed distribution for this terminal
type?
 Which service will the terminal type provide?*
 What are the mobile equipment characteristics?

LTE Terminal Types

LTE User Equipment Categories
Parameters Category 1 Category 2 Category 3 Category 4 Category 5
Peak Data Rate (DL) 10 Mbps 50 Mbps 100 Mbps 150 Mbps 300 Mbps
Peak Data Rate (UL) 5 Mbps 25 Mbps 50 Mbps 50 Mbps 75 Mbps
Block Size (DL) 10296 51024 102048 149776 299552
Block Size (UL) 5160 25456 51024 51024 75376
Max. Modulation (DL) 64QAM 64QAM 64QAM 64QAM 64QAM
Max. Modulation (UL) 16QAM 16QAM 16QAM 16QAM 64QAM
RF Bandwidth 20 MHz 20 MHz 20 MHz 20 MHz 20 MHz
Transmit Diversity 1-4 Tx 1-4 Tx 1-4 Tx 1-4 Tx 1-4 Tx
Receive Diversity Yes Yes Yes Yes Yes
Spatial Multiplexing (DL) Optional 2 X 2 2 X 2 2 X 2 4 X 4
Spatial Multiplexing (UL) No No No No No
MU-MIMO (DL) Optional Optional Optional Optional Optional
MU-MIMO (UL) Optional Optional Optional Optional Optional

Traffic Rasters
Traffic Rasters are arrays that store the distribution of traffic over an
area. They can be created either from the information in the Terminal
Types or from imported Live Traffic values. The name of the created
traffic raster will be the same as the name of the terminal type.
The Traffic Rasters enables you to:
 Obtain initial estimates of the equipment and configuration needed
for a nominal network. By visualising the array, you can then gain a
good idea of where to locate your sites.
 Can assess how your network performs in terms of capacity for a
mature network. Can verify site configuration is sufficient to match
the traffic spread over the network.

Creating Traffic Rasters

Traffic Rasters

Session 5
Simulating Network Performance

LTE Simulator Wizard

Simulation without Snapshots
If you run a simulation without running snapshots (static
analysis) you must ensure that the cell loading
parameters for the cells/sectors have been specified in
the Site Database.
The parameters are set on the Cell Load Levels subtab
under LTE Params tab.

Simulator Outputs
ASSET provides ways of setting your own array definitions, so that
you can specify exactly which arrays you want to be output when
you use the Simulator.
The easiest way is to use the Auto Setup option. This ensures that
all the relevant array types and their parameter combinations are
included in the simulation outputs for display and analysis.
You can also define your own customised collection of output array
types from the Simulator. This enables you to specify array
definitions to determine precisely which arrays you want to output
and display, in any combination of parameters you choose. This
method is probably only beneficial for advanced users.

Simulation – Best RSRP

Street Coverage prediction analysis using the Vector
Restriction feature
Best RSRP is calculated for whole 2D View Best RSRP is calculated to streets only

Simulation – RSRQ

Simulation – Cell Centre / Cell Edge

Simulation – Achievable DL Bearer

Simulation – DL RS SINR

Simulation – DL Transmission Mode

Information about Simulated Terminals
 The aim of this feature is to provide the user with a set of
arrays that show the locations of terminals generated by the
simulation snapshots, and to show whether the terminals
succeeded or failed to make a connection. The following
arrays are provided for each terminal type used in the
simulation.
• Terminal Info: Failure Rate
• Terminal Info: Failure Reason
• Terminal Info: Speed
 The arrays are only available in simulations that run snapshots,
and where the user has checked the Allow Terminal Info Arrays
box on the 2nd page of the simulation wizard.

Information about Simulated Terminals
Failure Reason array.
1 snapshot
Failure Reason array.
500 snapshots

Line-of-Sight array and improved MIMO
Modelling
 AIRCOM Enhanced Macrocell model (as well as some 3rd party prediction models –
complete list TBD) have the ability to produce line-of-sight (LOS) information for each
predicted location, in addition to the existing pathloss value.
 Using LOS info in a simulation can be used to improve MIMO modelling.
 MIMO schemes rely on there being a low correlation between the signal paths to the
receive elements of an antenna. Locations that have line-of-sight to an antenna are
more likely to have high correlation between signal paths to the antenna.
 The LTE simulator supports 3 basic MIMO schemes: SU-MIMO Multiplexing,
SU-MIMO Diversity, and MU-MIMO. A new page is added to the LTE simulation
wizard, providing the user with the option of enabling/disabling these 3 MIMO schemes
in LOS regions.
 If a prediction model
is used that does not
generate LOS info,
then the sim will treat
pathlosses from that
model as non-LOS.

Line-of-Sight array
and improved MIMO Modelling

Pixel Analyser
The Pixel Analyser visualises detailed signal strength information
that has been accumulated during a simulation.

Session 6
LTE Architecture

Flat Architecture
Traditional
Architecture
Control plane
User plane
GGSN
SGSN
RNC
NODE B
One Tunnel
Architecture
REL7
GGSN
SGSN
RNC
NODE B
SAE /GW– System
Architecture Evolution
MME - Mobility
Management Entity
eNodeB - evolved Node B
LTE
SAE GW
MME
eNODEB
IP Network
IP Network
IP Network

LTE-UE
MME
S6a
Serving
Gateway
S1-U
S11
S1-MME
PDN
Gateway
IMS
PCRF
S7
S5
Evolved
Node B
(eNB)
X2
LTE-Uu
HSS
Policy & Charging
Rule Function
LTE Network Architecture

Each eNB will have Physical Cell Identity (PCI). There are 504 different PCIs in
LTE. In addition, a globally unique cell identifier (GID)
Function of eNodeB
3GPP Release 8, the eNB supports the
following functions:
 Radio Resource Management
 Radio Bearer Control
 Scheduling (uplink and downlink )
 Radio Admission Control
 Connection Mobility Control
 IP header compression and
encryption of user data stream
 Selection of an MME
 Routing of User Plane data towards
Serving Gateway
 paging messages

Physical Cell Identity (PCI)
 Non-unique. There are
504 different PCIs in
LTE.
 Mobile is required to
measure the Reference
Signal Received Power
(RSRP) associated with
a particular PCI.
 It is important to
detect and resolve
local PCI conflicts.
PCI
PCI
Send Report

LTE-UE
MME
S6a
Serving
Gateway
S1-U
S11
S1-MME
PDN
Gateway
IMS
PCRF
S7
S5
Evolved
Node B
(eNB)
X2
LTE-Uu
HSS
Policy & Charging
Rule Function
EPS Bearer
The QoS parameters associated to the bearer are:
QCI, ARP, GBR and MBR
The QoS model in EPS is mostly based on DiffServ concepts
EPS Bearer in LTE

LTE Functional Elements - eNodeB
eNB
eNodeB
Radio Resource
Management
•Bearer & Admission
control
•RF Measurement
Reporting
Scheduling
•Dynamic resource
allocation to UE’s
•Transmission of
Pages & broadcast
information
Network Access
Security (PDCP)
•IP header
compression
•Ciphering of user
data stream
EPC Network
Selection
•MME Selection at UE
attachment
•User Plane routing to
SAE-GW
Combines the functionality of the UMTS NodeB & RNC

LTE Functional Elements - MME
MME
Mobility
Management
Entity
EPC Access
•Attachment &
Service Request
•Security &
Authentication
Mobility
•MME Selection for
Intra-LTE handovers
•SGSN Selection for
3GPP I-RAT
Handover
UE Tracking and
Reach-ability
•Tracking Area List
Management (idle or
active)
Bearer
management
•Dedicated bearer
establishment
•PDN GW & SAE-GW
selection
Equivalent to the SGSN for the Control Plane

LTE Functional Elements – S-GW
S-GW
SAE Gateway
Packet routing &
forwarding
between EPC &
eUTRAN
Local Mobility
Anchor for Inter
eNB handover
I-RAT Mobility
Anchor Function
• 3GPP 2G/3G Handover
• Optimized Handover
Procedures (e.g. in
LTE-CDMA)
Lawful
Interception
Equivalent to the SGSN for the User Plane

LTE Functional Elements – P-GW
P-GW
PDN Gateway
UE IP address
allocation
Policy
enforcement
(QoS)
Charging
support
Lawful
Interception
Mobility Anchor
between 3GPP
& non-3GPP
access systems
Equivalent to the GGSN

Self Organising Networks (SON)
The scope of Release 8 of SON:
 Automatic inventory
 Automatic software download
 Automatic Neighbour Relation
 Automatic Physical Cell ID (PCI) assignment
The next release of SON, as standardised in Release 9, will provide:
 Coverage & Capacity Optimisation
 Mobility optimisation
 RACH optimisation
 Load Balancing optimisation

Release 8
 Data Rate: Peak data rates target 100 Mbps (downlink) and 50 Mbps
 (uplink) for 20 MHz spectrum allocation, assuming 2 receive antennas
 and 1 transmit antenna at the terminal

Release 8
 Latency: The one-way transit time between a packet being
available at the IP layer in either the UE or radio access network
and the availability of this packet at IP layer in the radio access
network/UE shall be less than 5 ms
 Also C-plane latency shall be reduced, e.g. to allow fast transition
times of less than 100 ms from camped state to active state

Radio Resource Control (RRC)
RRC
 Managing RRC connection
 Mobility handling during RRC
connected mode
 Cell selection and re-selection
 Interpreting broadcast system
information
 Managing radio bearers
 Measurement reporting and control
 Ciphering control
Signalling Radio Bearers (SRB)
 Radio bearers are used only to carry
the RRC and NAS messages
 SRBs are divided into 3 types:
1. Signalling Radio Bearer 0: SRB0
FDD | TDD - Layer 1
( DL: OFDMA, UL: SC-FDMA )
Medium Access Control (MAC)
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
(Radio Resource Control)
IP / TCP | UDP | …
Application Layer
NAS Protocol(s)
(Attach/TA Update/…)
C plane signalling u plane Data

Admission
Control
Admission
Control
FDD | TDD - Layer 1
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
Application Layer
NAS Protocol(s)

The purpose of this procedure:
 Establish/ Modify/ Release RBs
 Perform Handover
 Configure /modify measurements
FDD | TDD - Layer 1
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
Application Layer
NAS Protocol(s)

 To re-establish the RRC connection
 A UE in CONNECTED state in order to
continue the RRC connection
 This succeeds only if a valid context exists
FDD | TDD - Layer 1
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
Application Layer
NAS Protocol(s)

 To activate security after the RRC
connection establishment, using
SRB1
FDD | TDD - Layer 1
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
Application Layer
NAS Protocol(s)

The purpose of this procedure is
the release of:
 SRB
 EPS Bearers
 ALL Radio resources
FDD | TDD - Layer 1
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
Application Layer
NAS Protocol(s)

 To transmit paging information to
UE in RRC IDLE State
 To inform UE in RRC IDLE about
system information change
SIBs
FDD | TDD - Layer 1
Transport Channels
RLC
(Radio Link
Control)
…
…
RLC
(Radio Link
Control)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
RLC
(Radio Link
Control)
PDCP
(Packet Data
Convergence
Protocol)
Logical Channel
(E-)RRC
Application Layer
NAS Protocol(s)

Signalling Radio Bearer
Signalling Radio Bearers (SRB)
are defined as Radio bearers
that are used only to transmit
RRC and NAS
 Signalling Radio Bearer 0:
SRB0: RRC message using
CCCH logical channel.
SRB1: is for transmitting NAS
messages over DCCH logical
channel.
SRB2: is for high priority RRC
messages. Transmitted over
DCCH logical channel
DTCH DCCH
Logical channels
DL-SCH
Transport
channels
Physical
channels
PDSCH
CCCH BCCH

Field Results from LTE Trial
Objective: The purpose of the test is to validate that the
EPS is able to pass ICMP packets to/from a test server
under unloaded and loaded conditions using a 5 MHz x 5
MHz FDD channel bandwidth
Max RTT
(ms)
Min RTT
(ms)
Av RTT
(ms)
PING
Req
PING
Res
PING
Loss
Success
Rate
PING
NOLOAD
18 15 16.25 104 99 5 95.2%
PING LOAD 168 15 20.71 109 104 5 95.2%

What Tests Need to be Done?
 Latency from UE to
Server using a 5
MHz x 5 MHz FDD
channel bandwidth
32 B 64 B 256 B 512 B 1024 B
EXC RTT 26.9 30.2 41.0 38.2 41.1
GOOD RTT 28.5 35.6 35.7 43.0 43.1
POOR RTT 28.1 35.2 51.5 59.4 155.1
0
20
40
60
80
100
120
140
160
180
RTT
(ms)
RTT vs Payload Size

Air Interface – Rel’99
IDLE
CELL DCH
QoS
CELL FACH
NO QoS
CELL URA CELLPCH
CELL SELECTION CELL SELECTION
CELL SELECTION
CELL SELECTION

UE States – LTE
RRC IDLE
RRC
CONNECTED
Handover
CELL SELECTION
This will reduce Latency
Question: Will there be more handovers with LTE?

LTE Devices – UE Categories

3G Services and QoS Classes
 Each application is
different in nature
 Some are high delay
Critical
Video Telephony
Streaming Video
Radio Tuner
Computer Games
Web Browsing
E-mail
Location Services
Server Backups
Casual
NRT
RT
INTEGRITY Telephony
Videotelephony
File
downloading
Web
browsing
Mail
downloading
Calendar
synchronisation
Teleworking
Teleshopping
Streaming
video
Streaming
music
UMTS
Telephony

Quality of Service
Traffic Class Conversational Streaming Interactive Background
Maximum Bit Rate X X X X
Delivery Order X X X X
Maximum SDU Size X X X X
SDU Format Information X X X X
SDU Error Ratio X X
Residual Bit Error Ratio X X X X
Delivery of Erroneous
SDUs X X X X
Transfer Delay X X
Guaranteed Bit Rate X X
Traffic Handling Priority X
Allocation/Retention
Priority X X

Services/Applications
Traffic Class Conversational Streaming Interactive Background
Speech X
Video Call X
Streaming Video X
Streaming Audio X
Web Browsing X
Email X
Email (Background) X
VoIP X
Gaming X
Presence X

LTE Quality of Service

LTE QoS
 Allocation and Retention
Priority (ARP): Within each
QoS class there are different
allocation and retention
priorities
 The primary purpose of ARP is
to decide whether a bearer
establishment / modification
request can be accepted or
needs to be rejected in case of
resource limitations (typically
available radio capacity in case
of GBR bearers)
In addition, the ARP can be used (e.g. by the eNodeB) to decide which bearer(s)
to drop during exceptional resource limitations (e.g. at handover)

Questions
1. Give a example of layer 4 protocol?
2. Give a example of layer 3 protocol?
3. What is the function of ARP?
4. What does QCI 1 mean?

Questions
5. How has Latency been reduced in LTE?
6. What is meant by 4x2?
7. What is meant by GSM re-farming?
8. What is a PCI?
9. Give some of the functions of SON for Rel’8?
10. What is EPS Bearer?

Session 7
LTE Mobility Management

Air Interface – Rel’99 / Rel 4
IDLE
CELL DCH
QoS
CELL FACH
NO QoS
CELL URA CELLPCH

LTE – Always On
 In the early deployment phase, LTE coverage will certainly be
restricted to city and hot spot areas.
 MORE HO’s than Rel’99
LTE
Connected
LTE _IDLE
Cell DCH
Connected
Cell FACH
Cell URA
Cell PCH
IDLE GSM/GPRS
IDLE
GSM
Connected
GPRS
Packet Transfer
Handover Handover
Reselection
Connection Establishment/Release
Connection Establishment/Release
Connection
Establishment/Release

UE Power-up UE Power up
DL Syn and Physical Channel ID
Find MIB – System BW
MCC +MNC
SIB’s supported
PCFICH Processing-
Knows the set up of PDCCH
Retrieval of SIBs
Cell Selection Parameters
Cell Selection
Successful
Pre-amble / Attach
Yes
Acquire another
LTE Cell
PLMN ID matches
Cell Barred
After Attach –Defaulf
Bearer/IP adress

Cell Selection
 After a UE has selected a PLMN, it performs cell selection – in other
words, it searches for a suitable cell on which to camp
 While camping on the chosen cell, the UE acquires the system
information that is broadcast
 Subsequently, the UE registers its presence in the tracking area,
after which it can receive paging information which is used to notify
UEs of incoming calls
eNB When camped on a cell, the UE regularly
verifies if there is a better cell; this is
known as performing cell reselection.

LTE-UE
MME
S6a
Serving
Gateway
S1-U
S11
S1-MME
PDN
Gateway
Internet
PCRF
S7
S5
Evolved
Node B
(eNB)
X2
LTE-Uu
HSS
EPS Mobility Management 2 states:
EMM-DEREGISTERED
EMM-REGISTERED
EPS Mobility Management

EPS Mobility Management - 2 States
EMM-DEREGISTERED:
 In this state the MME holds no valid location
information about the UE
 Successful Attach and Tracking Area Update
(TAU) procedures lead to transition to EMM-
REGISTERED
EMM-REGISTERED:
• In this state the MME holds location
information for the UE at least to the accuracy
of a tracking area
• In this state the UE performs TAU procedures,
responds to paging messages and performs the
service request procedure if there is uplink data
to be sent
MME
MME

Tracking Area Update – IDLE
MME HSS
s6a
NAS: Tracking Area
update
LTE Non Access Stratum (NAS)
The LTE NAS protocol software
enables communication with the
MME in the LTE core network and
handles functions of mobility
Tracking Area
Tracking Area
Home
Tracking Area Identity = MCC (Mobile
Country Code), MNC (Mobile Network
Code) and TAC (Tracking Area Code

Tracking Area Update – IDLE
Tracking areas are allowed to overlap: one cell can belong to
multiple tracking areas
TAI1-2
TAI2
TAI2
TAI2
TAI3
TAI3
TAI3
TAI3
TAI2
TAI2
TAI2
TAI2
TAI2
TAI2
TAI2
TAI2
TAI1
TAI1
TAI1
TAI1-2
NAS: Tracking Area
update
MME

MME
Serving
Gateway
S1-MME
(Control Plane)
S1-U
(User Plane)
NAS Protocols
S1-AP
SCTP
IP
L1/L2
User PDUs
GTP-U
UDP
IP
L1/L2
eNB
Tracking Area Update Request
S-TMSI/IMSI, PDN address
allocation Tracking Area Update Accept
Tracking Area Update Complete
LTE Functional Nodes - Management Entity
(MME)
 Tracking area (TA) is similar to
Location/routing area in 2G/3G
 Tracking Area Identity
 MCC (Mobile Country Code)
 MNC (Mobile Network Code)
 TAC (Tracking Area Code)

 The Globally Unique MME Identifier (GUMMEI) is constructed from the
MCC, MNC and MME Identifier (MMEI).
 Within the MME, the mobile is identified by the M-TMSI.
Globally Unique Temporary ID
MCC + MNC + MMEI
GUMMEI
M-TMSI
MME
MME MME POOLING
Globally Unique Temporary ID

Context Request
Context Request
 A context request includes
old GUTI, complete TAU
request, P-TMSI, MME
address etc. Basically this
message is sent by new
MME to old MME to inquire
about UE's authenticity, the
bearers created if any etc.
Context Response
 Context response include
IMSI, EPS bearers context,
SGW address and etc.
Create Session Request/Response: If there was no change in SGW there will not be this message.

RRC States – Idle OR Connected
In the early deployment phase, LTE coverage will certainly
be restricted to city and hot spot areas.
LTE
Connected
LTE _IDLE
Cell DCH
Connected
Cell FACH
Cell URA
Cell PCH
IDLE
GSM/GPRS
IDLE
GSM
Connected
GPRS Packet
Transfer
Handover Handover
Cell Selection
/Reselection
Connection
Connection
Connection
Establishment/
Release

Physical channels
20Mhz
BW
MIB
BW = 1.08Mhz
BCCH
BCH
PBCH
MIB
DL-SCH
PDSCH
Logical channels
Transport channels
RRC IDLE

The UE moving towards a new cell and identifies the Physical Cell Identity
(PCI) based on the Synchronisation signals
Physical Cell Identity (PCI) = 504
P-SCH S-SCH
Physical Cell Identity (PCI)
 P-SCH: for cell search and
identification by the UE -Carries
part of the cell ID (one of 3
orthogonal sequences)
 S-SCH: for cell search and
identification by the UE Carries
the remainder of the cell ID (one
of 168 binary sequences)

Measured
neighbours
PCI
Best ranked cell
Measurement criteria
S – criteria
Suitable
neighbours
R – criteria
Re-selection if not serving cell
neighboring cell was ranked with the highest
value R
Srx > Q rxlevmeas – (qrxlevmin – Qrelevmin
offset)-P Compensation
PCI PCI
PCI
P Compensation = max(Pamax-PbMax)
Qrxlevmin SIB1
Cell Reselection:

LTE_ACTIVE idle
For a cell to be suitable:
S rx level>0
Srx > Q rxlevmeas – (qrxlevmin – Qrelevmin offset)
RRC – Idle
Cell Selection done by UE
Base on UE Measurements
Q rxlevmeas
Reference signals
are transmitted in
ALL radio blocks
LTE_ACTIVE IDLE (Cell Selection)

For a cell to be suitable:
S rx level>0
Srx > Q rxlevmeas – (qrxlevmin – Qrelevmin offset)
Srx = -100 – (-80) = -20 (Will not do cell selection)
Q rxlevmeas=-100dBm
Will not do cell
selection
Q qrxlevmin =-80dBm
Q rxlevmeas
LTE_ACTIVE IDLE (Cell Selection)

Measured
neighbours
Best ranked cell
Measurement criteria
S – criteria
Suitable
neighbours
R – criteria
Rs = Qmeas,s + Qhysts cell)
Rn = Qmeas,n - Qoffsets,n
for candidate neighbouring cells for cell
reselection
PCI PCI PCI
PCI
Cell Reselection: R-Criterion

Cell Reselection: R-Criterion
Rs = Qmeas,s + Qhysts (for the serving
cell)
Qmeas,n
Qmeas,s
RSRP
(dBM)
Rs
Rn
Qoffsets,n
Qhysts
Rn > Rs =>“cell reselection“
Treselection
the time interval value Treselection,
whose value ranges between 0 and
31 seconds

Measurement Rules
 In RRC_IDLE, cell re-selection between frequencies is based on
absolute priorities, where each frequency has an associated
priority. Cell-specific default values of the priorities are provided
via system information.
 E-UTRAN may assign UE-specific values upon connection release.
 In case equal priorities are assigned to multiple cells, the cells are
ranked based on radio link quality.
Measurement rules
Which frequencies/ RATs to measure:
high priority
high priority + intra-frequency

Handover – RRC Connected

Handover – RRC Connected
In RRC_CONNECTED, the E-UTRAN decides to which cell a UE should hand
over in order to maintain the radio link.
In LTE the UE always connects to a single cell only – in other words, the
switching of a UE’s connection from a source cell to a target cell is a hard
handover.

Measurement Report Triggering
For LTE, the following event-triggered
reporting criteria are specified:
 Event A1. Serving cell becomes
better than absolute threshold
worse than absolute threshold
 Event A3. Neighbour cell becomes
better than an offset relative to the
serving cell
 Event A4. Neighbour cell becomes
better than absolute threshold
worse than one absolute threshold
and neighbour cell becomes better
than another absolute threshold
Source
eNodeB
DCCH: RRC
Measurement Control
DCCH: RRC
Measurement Report

Measurement Report Triggering
For inter-RAT mobility, the
following event-triggered reporting
criteria are specified:
 Event B1. Neighbour cell
becomes better than absolute
threshold
 Event B2. Serving cell becomes
worse than one absolute
threshold and neighbour cell
becomes better than another
absolute threshold
Source
eNodeB
DCCH: RRC
Measurement Control
DCCH: RRC
Measurement Report

LTE Reference Signal Received Quality (RSRQ)
 The RSRQ is defined as the ratio:
N · RSRP/(LTE carrier RSSI)
 where N is the number of Resource Blocks (RBs) of the LTE
carrier RSSI measurement bandwidth.
 The measurements in the numerator and denominator are
made over the same set of resource blocks.
 While RSRP is an indicator of the wanted signal strength,
RSRQ additionally takes the interference level into account
due to the inclusion of RSSI.

User Plane Switching in Handover
RLC
RLC
RLC
RLC
RLC RLC
X2
Connection

Event A3. Neighbour cell becomes better than an offset relative to the serving cell
1
2
3
4
Target cell
Source cell
Handover Timings
1. UE identifies the target
cell
2. Reporting range fulfilled
3. After UE has averaged the
measurement, it sends
measurement report to
source eNodeB
4. Source eNodeB sends
handover command to
the UE

Handover
Source
eNodeB
Target
eNodeB
DCCH: RRC Measurement Control
DCCH: RRC
Measurement Report Handover
Decision X2: Handover Request
X2: Handover Request Ack
HO Command
Admission
Control
The event detected and
reported is the event A3
within 3GPP LTE
The UE makes
periodic
measurements
of RSRP and
RSRQ based

Handover
Source
eNode
B
Target
eNode
B
Forward
Packets to
target X2: Handover
Request
HO
Command
Buffer
Packets

Handover - Buffer Forwarding
User Plane ACK
Source
eNodeB
Target
eNodeB
Forward Packets to
target
Switch path Request
HO Command
Buffer Packets
MME SAE
User Plane UpdateRequest
Switch DL path
Switch path Ack

Handover
Source
eNodeB
Target
eNodeB
DCCH: RRC Measurement
Configuration
DCCH: RRC
Measurement Report
Handover
Decision
X2: Handover Request
X2: Handover Request Ack
DCCH: RRC Connection
Reconfiguration
In LTE, data buffering in the DL occurs at the eNB
because the RLC protocol terminates at the eNB.
Therefore, mechanisms to avoid data loss during
inter- eNB handovers is all the more necessary when
compared to the UMTS architecture where data
buffering occurs at the centralised Radio Network
Controller (RNC) and inter-RNC handovers are less
frequent.
RRCConnectionReconfigurationComplete message.

Handover
IP
L2 Ethernet
UDP
GTP -C
L1-SDH
Serving Gateway
MME
IP
L2
Ethernet
UDP
GTP -C
L1-SDH
SCTP
IP
S1AP
NAS
L2
(Ethernet)
IP
L2 Ethernet
UDP
GTP -U
L1-SDH
MAC
PHY
RLC
PDCP
IP
TCP/UDP
User Plane
MAC
PHY
RLC
RRC
NAS
Control
DATA
SCTP
IP
S1AP
NAS
L2
(Ethernet)
MAC
PHY
RLC
RRC
NAS
Control
S1- Control
MME
DIRECTION
Connected Mode Mobility
In LTE_ACTIVE, when a UE moves between two LTE cells

Questions
1. Define the following:
a) Reference Signal Received Quality (RSRQ)
b) E-UTRA RSSI
c) Reference Signal Received Power (RSRP),

Questions
2. What is a PCI and how many are there?

Questions
4. What is the difference between PCI and global cell ID?

Questions
5. The total number of handovers are likely to be higher
in LTE than in UMTS. Why?

Thank you

156514180-AIRCOM-Asset-LTE-Basics-and-Asset.pdf

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