aircom asset lte basics and asset
DESCRIPTION
Propagation Model Calibration for LTE NetworkTRANSCRIPT
1
© 2012 AIRCOM International Ltd
Section 1: LTE Air-Interface Instructor – Ishan Marwah
2
© 2012 AIRCOM International Ltd
Roadmap
GSM
EDGE
WCDMA
2G 2.5G 3G phase 1
GPRS
Evolved 3G
HSDPA
HSUPA*
2000/2001 2003/2004 2005 2007
LTE
2010
3
© 2012 AIRCOM International Ltd
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
4
© 2012 AIRCOM International Ltd
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
5
© 2012 AIRCOM International Ltd
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
6
© 2012 AIRCOM International Ltd
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
7
© 2012 AIRCOM International Ltd
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
8
© 2012 AIRCOM International Ltd
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
9
© 2012 AIRCOM International Ltd
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
10
© 2012 AIRCOM International Ltd
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).
11
© 2012 AIRCOM International Ltd
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
12
© 2012 AIRCOM International Ltd
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
13
© 2012 AIRCOM International Ltd
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
14
© 2012 AIRCOM International Ltd
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
15
© 2012 AIRCOM International Ltd
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
16
© 2012 AIRCOM International Ltd
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)
17
© 2012 AIRCOM International Ltd
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
18
© 2012 AIRCOM International Ltd
LTE Bands
19
© 2012 AIRCOM International Ltd
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
20
© 2012 AIRCOM International Ltd
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
21
© 2012 AIRCOM International Ltd
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
22
© 2012 AIRCOM International Ltd
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
Slot Structure and Physical Resources
23
© 2012 AIRCOM International Ltd
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
24
© 2012 AIRCOM International Ltd
Bandwidth (MHz)
1.4 3 5 10 15 20
# of RBs 6 15 25 50 75 100
Subcarriers 72 180 300 600 900 1200
Slot Structure and Physical Resources
25
© 2012 AIRCOM International Ltd
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.
26
© 2012 AIRCOM International Ltd
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
27
© 2012 AIRCOM International Ltd
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
28
© 2012 AIRCOM International Ltd
Slot Structure and Physical Resources
Each 1ms Transmission Time Interval (TTI) consists of two slots (Tslot)
29
© 2012 AIRCOM International Ltd
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
30
© 2012 AIRCOM International Ltd
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
31
© 2012 AIRCOM International Ltd
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
32
© 2012 AIRCOM International Ltd
Configuration of Carrier - 1 Antenna
Carrier 1
Overhead REF, Control, Broadcast, Syn
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
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.
33
© 2012 AIRCOM International Ltd
Configuration of Carrier - 2 Antenna
Carrier 1
Overhead REF, Control, Broadcast, Syn
Downlink Reference Signal Structure
The downlink reference signal structure is important for channel estimation.
The principle of the downlink reference signal structure for 2 antenna.
Ref Signal TX2= 16 for 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.
34
© 2012 AIRCOM International Ltd
Configuration of Carrier - 3 Antenna
Carrier 1
Overhead REF, Control, Broadcast, Syn
Downlink Reference Signal Structure
The downlink reference signal structure is important for channel estimation.
The principle of the downlink reference signal structure for 2 antenna.
Ref Signal TX3= 20 for 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.
35
© 2012 AIRCOM International Ltd
Configuration of Carrier - 4 Antenna
Carrier 1
Overhead REF, Control, Broadcast, Syn
Downlink reference signal structure The downlink reference signal structure is important for channel estimation. The principle of the downlink reference signal structure for 2 antenna. Ref Signal TX3= 20 for 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.
36
© 2012 AIRCOM International Ltd
Type1-DL Frame
37
© 2012 AIRCOM International Ltd
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 and\or control signalling on the PUCCH
• mainly used for channel estimation for coherent demodulation
• transmitted on 2 symbols in each subframe
38
© 2012 AIRCOM International Ltd
Type1- UL Frame
39
© 2012 AIRCOM International Ltd
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)
40
© 2012 AIRCOM International Ltd
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.
41
© 2012 AIRCOM International Ltd
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
42
© 2012 AIRCOM International Ltd
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
43
© 2012 AIRCOM International Ltd
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
What is the free space
path loss at:
1800Mhz at 10Km
20 log (10) + 20log1800
=20 +65
=32.5+85dB
=117.5
What is the free space
path loss at:
1800Mhz at 100Km
20 log (100) + 20log10x1800
=40 +65
=32.5+105dB
=137
20dB different
44
© 2012 AIRCOM International Ltd
Free Space Path Loss Formula at 900Mhz: Lo = 32.5 + 20 log10(d) + 20 log10(fMhz) dBm
What is the free space
path loss at:
900Mhz at 1Km
20 log (1) + 20log x 900
=0 + 59
=32.5 + 59dB
=91.5dB
What is the free space
path loss at:
900Mhz at 10Km
20 log (10) + 20log x 900
=20 +59
=32.5+79dB
=111.5dB
What is the free space
path loss at:
900Mhz at 100Km
20 log (100) + 20log10x900
=40 +59
=32.5+99dB
=131.5
20dB different
45
© 2012 AIRCOM International Ltd
Examples What is the free space
path loss at:
1800Mhz at 1Km
20 log (1) + 20logx1800
=0 +65
=32.5 + 65 dB
=97.5
What is the free space
path loss at:
1800Mhz at 10Km
20 log (10) + 20log1800
=20 +65
=32.5+85dB
=117.5
What is the free space
path loss at:
1800Mhz at 100Km
20 log (100) + 20log10x1800
=40 +65
=32.5+105dB
=137
What is the free space
path loss at:
900Mhz at 1Km
20 log (1) + 20log x 900
=0 + 59
=32.5 + 59dB
=91.5dB
What is the free space
path loss at:
900Mhz at 10Km
20 log (10) + 20log x 900
=20 +59
=32.5+79dB
=111.5dB
What is the free space
path loss at:
900Mhz at 100Km
20 log (100) + 20log10x900
=40 +59
=32.5+99dB
=131.5
46
© 2012 AIRCOM International Ltd
Frequency Band Considerations 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
47
© 2012 AIRCOM International Ltd
Frequency Band Considerations 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.
48
© 2012 AIRCOM International Ltd
Frequency Band Considerations 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
49
© 2012 AIRCOM International Ltd
Frequency Band Considerations
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.
50
© 2012 AIRCOM International Ltd
Questions
51
© 2012 AIRCOM International Ltd
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?
52
© 2012 AIRCOM International Ltd
Questions
2. What is the maximum bit rate if you assign a bandwidth of 20Mhz to a sector and a UE is allocated all RB?
53
© 2012 AIRCOM International Ltd
Questions
3. What is the maximum bit rate if you assign a bandwidth of 5Mhz to a sector and a UE is allocated all RB?
54
© 2012 AIRCOM International Ltd
Questions
4. What is meant by Normal type1?
5. Compare band 13 to band 1?
6. What is meant by GSM re-farming?
55
© 2012 AIRCOM International Ltd
Session 02
Setting up a LTE Network in Asset
56
© 2012 AIRCOM International Ltd
Antenna Database
Antenna Information and Mask
57
© 2012 AIRCOM International Ltd
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.
58
© 2012 AIRCOM International Ltd
Std. Macrocell Propagation Model
Asset Standard Macrocell model
lossClutterlossndiffractioKdoglHgloK
gHloKogHlKHKdoglKKPL
eff
effmsms
)(7)()(6
543)(21
59
© 2012 AIRCOM International Ltd
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
60
© 2012 AIRCOM International Ltd
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
61
© 2012 AIRCOM International Ltd
MME and SAE-GW Support
62
© 2012 AIRCOM International Ltd
LTE Frame Structures
63
© 2012 AIRCOM International Ltd
LTE Frequency Bands
64
© 2012 AIRCOM International Ltd
LTE Carriers
65
© 2012 AIRCOM International Ltd
LTE Carriers
66
© 2012 AIRCOM International Ltd
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
67
© 2012 AIRCOM International Ltd
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
68
© 2012 AIRCOM International Ltd
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.
69
© 2012 AIRCOM International Ltd
Interference Coordination Schemes
70
© 2012 AIRCOM International Ltd
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
71
© 2012 AIRCOM International Ltd
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
72
© 2012 AIRCOM International Ltd
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 (Data\Traffic)
• 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
73
© 2012 AIRCOM International Ltd
SU-MIMO
• This includes conventional techniques such as
• Cyclic Delay Diversity
• Transmit\Receive 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 rate\throughput by transmitting multiple streams of data dedicated for a single user
74
© 2012 AIRCOM International Ltd
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
75
© 2012 AIRCOM International Ltd
Lookup Table for AAS
76
© 2012 AIRCOM International Ltd
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.
77
© 2012 AIRCOM International Ltd
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
78
© 2012 AIRCOM International Ltd
AAS Settings in Site DB
79
© 2012 AIRCOM International Ltd
LTE Parameters
80
© 2012 AIRCOM International Ltd
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.
81
© 2012 AIRCOM International Ltd
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
82
© 2012 AIRCOM International Ltd
Session 03
Predicting and Displaying Coverage
83
© 2012 AIRCOM International Ltd
Predicting Coverage
84
© 2012 AIRCOM International Ltd
Best RSRP Coverage Example
85
© 2012 AIRCOM International Ltd
Array Display Properties To customise the arrays displayed in the Map View window, Use the Show Data Types button.
86
© 2012 AIRCOM International Ltd
Coverage Reports/Statistics
Once coverage arrays have been created, you can generate coverage statistics.
87
© 2012 AIRCOM International Ltd
Coverage Reports/Statistics
88
© 2012 AIRCOM International Ltd
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.
89
© 2012 AIRCOM International Ltd
Session 04
Traffic Planning on a LTE Network
90
© 2012 AIRCOM International Ltd
Default LTE Bearers Bearers represent the air interface connections, performing the task of transporting voice and data information between cells and terminal types.
91
© 2012 AIRCOM International Ltd
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
92
© 2012 AIRCOM International Ltd
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.
93
© 2012 AIRCOM International Ltd
LTE Services and QoS Parameters
Name QCI Resource
Type
Priority
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
94
© 2012 AIRCOM International Ltd
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.
95
© 2012 AIRCOM International Ltd
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?
96
© 2012 AIRCOM International Ltd
LTE Terminal Types
97
© 2012 AIRCOM International Ltd
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
98
© 2012 AIRCOM International Ltd
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.
99
© 2012 AIRCOM International Ltd
Creating Traffic Rasters
100
© 2012 AIRCOM International Ltd
Traffic Rasters
101
© 2012 AIRCOM International Ltd
Session 5
Simulating Network Performance
102
© 2012 AIRCOM International Ltd
LTE Simulator Wizard
103
© 2012 AIRCOM International Ltd
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.
104
© 2012 AIRCOM International Ltd
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.
105
© 2012 AIRCOM International Ltd
Simulation – Best RSRP
106
© 2012 AIRCOM International Ltd
Street Coverage prediction analysis using the Vector
Restriction feature
Best RSRP is calculated for whole 2D View Best RSRP is calculated to streets only
107
© 2012 AIRCOM International Ltd
Simulation – RSRQ
108
© 2012 AIRCOM International Ltd
Simulation – Cell Centre / Cell Edge
109
© 2012 AIRCOM International Ltd
Simulation – Achievable DL Bearer
110
© 2012 AIRCOM International Ltd
Simulation – DL RS SINR
111
© 2012 AIRCOM International Ltd
Simulation – DL Transmission Mode
112
© 2012 AIRCOM International Ltd
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.
113
© 2012 AIRCOM International Ltd
Information about Simulated Terminals
Failure Reason array. 1 snapshot
Failure Reason array. 500 snapshots
114
© 2012 AIRCOM International Ltd
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.
115
© 2012 AIRCOM International Ltd
Line-of-Sight array and improved MIMO Modelling
116
© 2012 AIRCOM International Ltd
Pixel Analyser The Pixel Analyser visualises detailed signal strength information that has been accumulated during a simulation.
117
© 2012 AIRCOM International Ltd
Session 6
LTE Architecture
118
© 2012 AIRCOM International Ltd
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
119
© 2012 AIRCOM International Ltd
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
120
© 2012 AIRCOM International Ltd
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
121
© 2012 AIRCOM International Ltd
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
122
© 2012 AIRCOM International Ltd
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
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
123
© 2012 AIRCOM International Ltd
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
124
© 2012 AIRCOM International Ltd
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
125
© 2012 AIRCOM International Ltd
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
126
© 2012 AIRCOM International Ltd
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
127
© 2012 AIRCOM International Ltd
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
128
© 2012 AIRCOM International Ltd
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
129
© 2012 AIRCOM International Ltd
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
130
© 2012 AIRCOM International Ltd
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
2. Signalling Radio Bearer 1: SRB1
3. Signalling Radio Bearer 3: SRB3
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
131
© 2012 AIRCOM International Ltd
Radio Resource Control (RRC)
Admission
Control
Admission
Control
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
132
© 2012 AIRCOM International Ltd
Radio Resource Control (RRC)
The purpose of this procedure:
Establish/ Modify/ Release RBs
Perform Handover
Configure /modify measurements
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
133
© 2012 AIRCOM International Ltd
Radio Resource Control (RRC)
The purpose of this procedure:
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
( 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
134
© 2012 AIRCOM International Ltd
Radio Resource Control (RRC)
The purpose of this procedure:
To activate security after the RRC connection establishment, using SRB1
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
135
© 2012 AIRCOM International Ltd
Radio Resource Control (RRC)
The purpose of this procedure is the release of:
SRB
EPS Bearers
ALL Radio resources
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
136
© 2012 AIRCOM International Ltd
Radio Resource Control (RRC)
The purpose of this procedure:
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
( 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
137
© 2012 AIRCOM International Ltd
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.
Signalling Radio Bearer 1: SRB1: is for transmitting NAS messages over DCCH logical channel.
Signalling Radio Bearer 2: 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
138
© 2012 AIRCOM International Ltd
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%
139
© 2012 AIRCOM International Ltd
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
RT
T (
ms
)
RTT vs Payload Size
140
© 2012 AIRCOM International Ltd
Air Interface – Rel’99
IDLE
CELL DCH
QoS
CELL FACH
NO QoS
CELL URA CELLPCH
CELL SELECTION CELL SELECTION
CELL SELECTION
CELL SELECTION
141
© 2012 AIRCOM International Ltd
UE States – LTE
RRC IDLE
RRC
CONNECTED
Handover
CELL SELECTION
This will reduce Latency Question: Will there be more handovers with LTE?
142
© 2012 AIRCOM International Ltd
LTE Devices – UE Categories
143
© 2012 AIRCOM International Ltd
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
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
144
© 2012 AIRCOM International Ltd
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
145
© 2012 AIRCOM International Ltd
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
146
© 2012 AIRCOM International Ltd
LTE Quality of Service
147
© 2012 AIRCOM International Ltd
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)
148
© 2012 AIRCOM International Ltd
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?
149
© 2012 AIRCOM International Ltd
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?
150
© 2012 AIRCOM International Ltd
Session 7
LTE Mobility Management
151
© 2012 AIRCOM International Ltd
Air Interface – Rel’99 / Rel 4
IDLE
CELL DCH
QoS
CELL FACH
NO QoS
CELL URA CELLPCH
152
© 2012 AIRCOM International Ltd
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
153
© 2012 AIRCOM International Ltd
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
154
© 2012 AIRCOM International Ltd
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.
155
© 2012 AIRCOM International Ltd
LTE-UE
Evolved UTRAN (E-UTRAN)
MME
S6a
Serving
Gateway
S1-U
S11
Evolved Packet Core (EPC)
S1-MME
PDN
Gateway
Internet
PCRF
S7
S5
Evolved
Node B
(eNB)
X2
LTE-Uu
HSS
MME: Mobility Management Entity
EPS Mobility Management 2 states:
EMM-DEREGISTERED
EMM-REGISTERED
EPS Mobility Management
156
© 2012 AIRCOM International Ltd
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
157
© 2012 AIRCOM International Ltd
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
158
© 2012 AIRCOM International Ltd
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
159
© 2012 AIRCOM International Ltd
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)
160
© 2012 AIRCOM International Ltd
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
161
© 2012 AIRCOM International Ltd
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.
162
© 2012 AIRCOM International Ltd
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
Establishment/Release Connection
Establishment/Release
Connection
Establishment/
Release
163
© 2012 AIRCOM International Ltd
Physical channels
20M
hz B
W
MIB
BW = 1.08Mhz
BCCH
BCH
PBCH
MIB
DL-SCH
PDSCH
Logical channels
Transport channels
RRC IDLE
164
© 2012 AIRCOM International Ltd
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)
165
© 2012 AIRCOM International Ltd
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:
166
© 2012 AIRCOM International Ltd
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 RSRP (Reference Signal Received Power)
Reference signals are transmitted in ALL radio blocks
LTE_ACTIVE IDLE (Cell Selection)
167
© 2012 AIRCOM International Ltd
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 RSRP (Reference Signal Received Power)
LTE_ACTIVE IDLE (Cell Selection)
168
© 2012 AIRCOM International Ltd
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
169
© 2012 AIRCOM International Ltd
Cell Reselection: R-Criterion Rs = Qmeas,s + Qhysts (for the serving
cell)
Qmeas,n
Qmeas,s
RS
RP
(d
BM
)
Rs
Rn
Qoffsets,n
Qhysts
Rn > Rs =>“cell reselection“
Treselection
the time interval value Treselection,
whose value ranges between 0 and
31 seconds
170
© 2012 AIRCOM International Ltd
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
171
© 2012 AIRCOM International Ltd
Handover – RRC Connected
172
© 2012 AIRCOM International Ltd
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.
173
© 2012 AIRCOM International Ltd
Measurement Report Triggering
For LTE, the following event-triggered reporting criteria are specified:
Event A1. Serving cell becomes
better than absolute threshold
Event A2. Serving cell becomes 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
Event A5. 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
174
© 2012 AIRCOM International Ltd
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
175
© 2012 AIRCOM International Ltd
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.
176
© 2012 AIRCOM International Ltd
User Plane Switching in Handover
RLC
RLC
RLC RLC
RLC RLC
X2 Connection
177
© 2012 AIRCOM International Ltd
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
178
© 2012 AIRCOM International Ltd
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
179
© 2012 AIRCOM International Ltd
Handover
Source
eNode
B
Target
eNode
B
Forward
Packets to
target X2: Handover
Request
HO
Command
Buffer
Packets
180
© 2012 AIRCOM International Ltd
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
181
© 2012 AIRCOM International Ltd
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.
182
© 2012 AIRCOM International Ltd
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
DA
TA
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
183
© 2012 AIRCOM International Ltd
Questions 1. Define the following:
a) Reference Signal Received Quality (RSRQ)
b) E-UTRA RSSI
c) Reference Signal Received Power (RSRP),
184
© 2012 AIRCOM International Ltd
Questions
2. What is a PCI and how many are there?
185
© 2012 AIRCOM International Ltd
Questions
4. What is the difference between PCI and global cell ID?
186
© 2012 AIRCOM International Ltd
Questions
5. The total number of handovers are likely to be higher in LTE than in UMTS. Why?
187
© 2012 AIRCOM International Ltd
Thank you