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Transcript of LTE Presentation
LTE Technology Specs(2)
LTE Technology Specs
Two types for LTE frame structures:
LTE Frame Structure
Introduction to the past generations:
Analog not digital.
Lack of security.
Meaningless data service.
No roaming capability.
lack of capacity saturation
Higher capacity and security.
Offer SMS(Short Message Service).
Circuit switched data.
Data rate: 9.4Kbps circuit switched and 14.4Kbps for data service(Too slow).
Higher transmission rate:
-2Mbps for stationary or nomadic use.
-348Kbps for moving vehicle.
Theoretical data rate: 171.2Kbps.
Typical data rate: 4Kbps to 50Kbps.
(Packet switched data)
Theoretical data rate: 553.6Kbps.
Typical data rate: 120Kbps.
(Packet switched data)
High Speed Down-link Packet Access.
Data rate: 14.4Mbps.
High Speed Up-link Packet Access.
Data rate: 5.76Mbps.
High Speed Packet Access+.
Data rate: 28.8Mbps.
(Downlink and Uplink)
High data rates.
Improved user throughput.
Increased radio frequency deployment bandwidth.
Lower equipments costs than circuit switching 2G and 3G wireless infrastructure.
Flexibility to handle voice, data ,and future traffic requirements.
Increasing the user’s throughput.
Decreasing the latency factor.
Increasing the spectral efficiency.
To enhance Bandwidth
LTE provides channels with bandwidths starting from 1.4MHz up to 20MHz.
(1.4 - 3 - 5 - 10 - 15 - 20)MHz
To enhance SNR
LTE key technologies:
What is MIMO?
Shannon's theory states that:
So to enhance capacity of information of each user, we will enhance Bandwidth and Signal to Noise ratio.
Concerning Spectral Efficiency
1 Frame = 20 slot = 10ms.
1 slot = 0.5ms.
1 Subframe = 2 Slots = 1ms.
1 Slot = 7 Symbols ( Normal CP).
1 Slot = 6 Symbols ( Extended CP ).
10 Subframes for Downlink transmission.
10 Subframes for Uplink transmission.
TDD frame structure is the concept of “special subframes”:
This includes a DwPTS (Downlink Pilot Time Slot), GP (Guard Period) and UpPTS (Uplink Pilot Time Slot).
These have configurable individual lengths and a combined total length of 1ms.
10 subframes are shared between the uplink and the downlink.
Cellular Concept(amazing freq. reuse).
Increased spectrum flexibility: 1.4 - 20 MHz.
Download rates up to 300 Mbps and upload rates up to 75 Mbps
Low data transfer latencies.
Support mobility up to 500 KM/hr.
SC-FDMA for uplink.
Support FDD or TDD.
Support all freq. bands "700, 900, 1800, 1900, 2100, 2600, ...."
Spacing between subcarriers is 15 KHZ.
LTE Technology Specs(3)
Cyclic Prefix(No ISI).
IP V6 (Static IPs not Dynamic)
Apps like "HD video calls-HD video streaming-Mobile TV-IPTV-Cloud computing"
7 OFDM Symbols (Normal CP ) & 6 OFDM Symbols ( Extended CP ) :
Spacing between sub-carriers is 15 KHz, this achieves orthogonality.
FDMA vs. OFDMA
OFDMA vs. FDMA?
ISI and Cyclic Prefix.
Higher BW efficiency.
So ISI problem Happens
CP (Recovery from ISI)
NO ISI "CP".
Low hardware complexity.
High PAPR (Peak to Average Power Ratio).
Frequency Doppler shift.
Implementation of OFDMA (DL) and SC-FDMA (UL):
BCCH PCCH CCCH DCCH DTCH MCCH MTCH
CCCH DCCH DTCH
PCCH (DL, UL).
PSCH (DL, UL).
LTE Network Structure
Coverage of 4G cell.
Mod. and Demod. (QPSK-16QAM-64QAM).
Ciphering and Deciphering.
Allocation of subcarriers.
Release of subcarriers.
Power control commands.
MIMO (2*2 or 4*4).
Resource Block bitrate:
1) Master copy of the subscriber proﬁle.
2) Location info (MME).
1) Authentication and security.
2) TA updates.
3) Subscription profile of the served UE.
Asymmetric bandwidth assignment for FDD.
SONs "Self Organizing Networks" methodologies.
COMP “Coordinated multipoint”.
COMP “Coordinated multipoint”:
Network structure: Less no. of stages.
In case of handover: Less no. of stages.
Thank You for Your Time