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LTE Access Network
2
LTE Network and Interfaces
EPC
eUTRAN
UMTS/GERAN
WLAN
Internet
S1
SGi
S2 S3,S4
3
eUTRAN Architecture and Interfaces
SGW
eNB
MME
eNB
S1_MME UE and eNB
Signalling
S1_U User Plane Data
App Signalling
S11
X2
Signalling and Control User Data PGW
4
LTE Radio Interface Flexible Bandwidth Options
1.4 – 20 MHz
High Order Modulation and Coding QPSK, 16 QAM and 64 QAM
Adaptive modulation and coding
Robust OFDMA in the Downlink Multi-Carrier Transmission
Good Multipath Performance
Suited to Advanced Antenna Techniques
Efficient SC-FDMA in the Uplink Still good Multipath Performance
Decoding complexity in the eNB
More power efficient than OFDMA
Advanced Antenna Support MIMO, 2x2, 4x4
Beamforming
5
Typical Multipath Environment
OFDMA – Designed to offer good performance
in challenging environments
6
Shannon's Law and Capacity
Low Bandwidth
High Bandwidth
Low SNR
High SNR
7
Capacity in LTE
LTE supports Adaptive Modulation and Coding
Actual Capacity will depend on users location in the cell
SINR is the most important planning KPI
Average cell throughput will lower than quoted
maximums
5
8
The Capacity Planning Problem
100+ Mbps! Assumes good radio signal in
every part of the radio cell
QPSK 16QAM 64QAM
9
User Distribution in the Cell
User Distribution will impact average cell throughput
The resource scheduler in the eNB is very important
Scheduling may be different between vendors
QPSK 16QAM 64QAM
~10% of Area
~15% of Area
~75% of Area
10
The Radio Spectrum
UHF Band is very busy
Most mobile radio services operate in this band
Many frequencies in UHF are designated IMT bands
LTE can be deployed in any IMT Band
TV
TV
GSM
300 500 900 1500 1800 2500 3000 4000 MHz MHz
GSM
UMTS
WiFi
WiMAX
DECT
VLF
Very
Low
Freq
LF
Low
Freq
MF
Medium
Freq
HF
High
Freq
VHF
Very
High
Freq
UHF
Ultra
High
Freq
SHF
Super
High
Freq
3KHz 30KHz 300KHz 3MHz 30MHz 300MHz 3GHz 300GHz
IMT Bands
Shown in White
11
Which Radio Spectrum to Use?
12
13
14
Carrier Aggregation Options (basic)
f1 f2 f3 f4 f5
Band A Band B
a b c
a – intra-band, contiguous (R10 UL only)
b – intra-band, non contiguous (R10 UL Only)
c – inter-band
15
16
Heterogeneous – Dictionary Definition
heterogeneous
/ˌhetərəˈjēnēəs/
- composed of parts of different kinds; having widely
dissimilar elements or constituents
homogeneous /ˌhōməˈjēnēəs/
- composed of similar or identical parts or elements
17
Heterogeneous Network
Large, Small and Tiny Cells
Cells have different technologies with different physical
characteristics
Ideally all layers under the control of a single entity
Pico/
Enterprise Femto
WiFi
CSG Femto
2G
3G
3G/LTE
3G/LTE
3G/LTE
18
Small Cell Capacity Gains
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