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Copy of LTE Presentation
Transcript of Copy of LTE Presentation
GSM (Digital )
EGPRS (EDGE 2.75 G 384Kbps )
Dig Amps CDMA IS95A
Global System for Mobile Intoduced Sevices : SMS -Internet (9.6kbps) -Call Waiting Divert.
GPRS (2.5G) Ps Core Network
Internet 156 Kbps
Universal Mobile Telecomunication System Vedio Call
Higher Data Rate
Releases : R99 (3G): 2Mbps
R5 (HSDPA -3.5 G )
R6 (HSUPA -3.75G )
R7 (HSPA+) LTE
Long Term Evolution WHY LTE ? THE NEED FOR :
PS Optimized system
Higher Data Rates
High QoS LTE Specs Data Rate:100Mbps Dl -50 Mbps UL
Capacity : up to 200 users /cell
< 5ms latency .
Higher Mobility : 15 -120 Km/hr With high Performance.
Enhanced Services :ex EMBMS.
Spectrum Flexibilty : 1.25 - 20 MHZ.
Interoperability With Older Systems.
Reduced CAPEX &OPEX. LTE Architecture How did they think to reach the lte architecture
1) Latency 2 ) Network Core Reduction LTE Architecture Structure
1) EUTRAN 2)EPC
Has the functions of the NodeB and RNC.
Provides LTE coverage.
Manages Data resources.
Scdeduling of downlink and uplink.
Handles Handover decisions and commands. LTE LAYERS
LTE Layers (The Protocol Stack ) at the Air Interface (Between ENB & UE ) we divide the Protocol Stack into two Types
User plane . Control Plane - NAS ( Non Access Stratum )
Access information not included.
session Mangment .
Broad casting Information
- ERRC - RLC Buffering
Concatenating & Splitting
Handle ARQ - Physical Layer - MAC Scheduling
User Plane - IP Packet
- PDCP Header Compression For Ip Packet to be suitable For RlC Layer Using ROHC Techniques .
Cyphering and protection integrity. - RLC Buffering
Handle ARQ (For AK Mode Real Time PS ) CRC ( Cyclic Redundancy Check ) Forward Error Detection .
More reliable than Hard and Soft error detection
Previous Standards Operated On TB .
LTE Supports 2 Level Error Check And Operates on CBs.
LTE Supports 2 Level Early Stopping Technique .
-Previous Standards Started CRC Check after Iteration.
-Introduces Min number of iterations.
-Saves Hardware resources by at least 25%.
-Saves Power by at least 20%.
Channel Coding 1.Turbo Encoder
3 Levels of coding depending on Channel noise.
Code rate 1/3 only.Only code rates can be achieved by external rate matching.
Double-buffering allows the encoder to recieve data while processing the previous data block.
Latency Calculation L=D/fmax D=K+14 K: Block Size , D: Encoding Delay.
Throughput Calculation T= K*fmax/D .
Previous Standards worked on TB causing bottlenecks and data delay.
LTE Supports Pipeling which reduced hardware complexity. 2.Turbo Decoder Consists of two single soft-in soft-out(SISO) decoders ,which work iteratively.
Output of the first (upper decoder) feeds into the second to form a turbo decoding iteration.
Interleaver and deinterleaver blocks re-order data in this process.
Double-buffering supports reduced latency real-times applications.
Supports 2 level early stopping technique. Hybrid-ARQ Scrambler What is the Scrambler?
It is done by xoring data and scrambling codes.
Function: 1-Security. 2-Avoid long streams of ones. 3-Make it easier for regeneration of clock in PLL reciever.
Mobility management: Paging, Location update, Registration.
MME requests resources for the traffic from SGW.
Responsible for voice calls charging.
Responsible for roaming.
Note that all its functions are control only.
It is also called 3GPP anchor.
Connects between the LTE system and all other 3GPP systems.
Handles traffic data.
It is also called the non 3GPP anchor.
Connects between LTE systems and IEEE(Wi-Fi & Wi-Max).
Connects between LTE system servers and the internet.
Contains all LTE system database.
Responsible for Quality of Service between different PDNs.
Responsible for charging non real time data.
2)EPC Hybrid Automatic Repeat reQuest
H-ARQ is ablock in MAC layer do it's functionality in Physical Layer (Hybrid Functionality )
Rate Matching ( Puncturing )
-Chase Combining - Incremental Redundancy Combining
How H-ARQ Implemented in LTE .
Modulation / Mapping
QPSK / 16QAM / 64QAM
Diffrence Between 3 Schemes
Downlink , Up link
jointly processes 2 Codewords
Mapping the result on 2 diffrent Anttenas
configuring the anttena mapping to achive certian MIMO Scheme :
1) spatial Multiplexing
2) open loop transmit Diversity
3) Beam forming . Spatial Multiplexing
allows transmitting diffrent streams on the same
downlink resource block
SU -MIMO to achieve higher data rates.
Mu -MIMO to achieve higher capacity .
possible if the channel allows it . open loop transmit diversty
It is done to achive diversty
possible when transmitting one stream only
possible when spatial multiplexing is not possible How can we achieve diffrent MIMO schemes LTE Standard Dvided An antenna Mapping into 2 parts
Why we use OFDM?
-Multi Carrier Modulation Technique.
a. No need For Complex Equalizer
b. Frequency Selective Channels
c. Decreasing Impulse Noise Effect
ISI & CP.
Transmitter block digram :
- Serial to Parallel.
- Baseband Modulation.
- Parallel to serial.
- RF Modulation.
Pilots & time varriant channels.
Layer Mapping De multiplexes the code words symblos
into one or muliple layers
Pre Coding responsible for MIMO Schemes
provides selected MIMO schemes
Optimum precoding Matrix is Selected Based on predefinred code Book based on maximum capacity .
it is provided on uplink control channel and avaliable per resource blook(s) Resource Block Mapping overall time domain structure
function of resource block mapper
selection of resource block.
over all system block mapping
Presented by :
Amr Ahmed Abd Elfatah Selima
Amr Gamal Zaki
Gillan Mohamed Shaaban
Karim Shawky Aziz
Mohammed Osama Elbalkini
Mohamed Talaat Foad
Presented To :
Proffessor Abd ElHalim Zekry
Presentation Date :