High Academy for CommunicationCollaboration with Omdurman Islamic University

Presented by:

Swar Eldahb Taha Elbala

Supervisor:

Dr. Khalid Hamid Bilal

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E2E Delay Performance Evaluation in

LTE-Network

2013

Objective:

to evaluate End-to-End Delay in LTE network environment by using (VoIP) traffic & take into account the affecting parameters

End-to-End Delay

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What is LTE ?

In Nov. 2004, 3GPP began a project to define the long-term evolution (LTE) of Universal Mobile Telecommunications System (UMTS) cellular technology Higher performance Backwards compatible Wide application

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Evolution of Radio Access Technologies

802.16d/e

802.16m

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LTE Release 8 Key Features (1/2)

Very low latency (Delay) Short setup time & Short transfer delay Short hand over latency and interruption time

High spectral efficiency OFDM in Downlink Single‐Carrier FDMA in Uplink

Support of variable bandwidth 1.4, 3, 5, 10, 15 and 20 MHz

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LTE Release 8 Key Features (2/2)

Compatibility and interworking with earlier 3GPP Releases

FDD and TDD within a single radio access  technology

Efficient Multicast/Broadcast

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LTE Basic Concepts

LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) for downlink data transmission and Single Carrier FDMA (SC-FDMA) for uplink transmission

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FDM vs. OFDM

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LTE-Downlink (OFDM)

Improved spectral efficiency

Reduce ISI effect by multipath

Against frequency selective fading

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LTE Uplink (SC-FDMA) SC-FDMA is a new single carrier multiple access

technique which has similar structure and performance to OFDMA

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LTE Radio Access Network Architecture

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Generic Frame Structure

Allocation of physical resource blocks (PRBs) is handled by a scheduling function at the 3GPP base station (eNodeB)

Frame 0 and frame 5 (always downlink)

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Resource Grid

One frame is 10ms 10 subframes

One subframe is 1ms 2 slots

One slot is 0.5ms N resource blocks[ 6 < N < 110]

One resource block is 0.5ms and contains 12 subcarriers from each OFDM symbol

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Cyclic Prefixes

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Layered OFDMA

The bandwidth of basic frequency block is, 15–20 MHz

Layered OFDMA radio access scheme in LTE-A will have layered transmission bandwidth, support of layered environments and control signal formats

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Downlink System Model

Opportunistic Packet Scheduling Algorithms

Suitable for non real traffic It take into account channel quality and the

past user throughput

Proportional Fairness (PF)

PF equation

μi (t): data rate corresponding to the channel state of the user i

μi is the mean data supported by the channel

Opportunistic Packet Scheduling Algorithms

designed to support multiple real-time data users in CDMA-HDR system

It supports multiple data users with different QoS requirements.

Maximum Largest Weighted Delay First (M-LWDF)

M-LWDF Equation :

where μi (t) = data rate i is the mean data rate supported by the channel Wi (t) is the HOL packet delay ,where i=1,…,N are

weight takes into account instantaneous channel variations

and delays in the case of video service

Exponential Proportional Fairness (EXP/PF)

This algorithm has been designed to increase the priority of real-time flows with respect to non-real-time ones

this means that an user can belong (RT) or (NRT) services.

Equation:

where:

Simulation & Performance Evaluation

performance evaluation for LTE-SIM Simulation Environments output results

LTE-SIM

Open source software ,written c ++ & working Linux environments

LTE-Sim has been conceived to simulate uplink and downlink scheduling strategies in multi-cell/multi-users environments taking into account user mobility, radio resource optimization, frequency reuse techniques and other aspects

LTE nodes model

Simulation Design:

In the simulation design we will create three scenarios as follow:Scenario 1:Single cellScenario 2: Single cell with interference Scenario 3:Multiple cell

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1 Scenario 1: Single cell

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Results 1

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Results 2

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Results 3

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Scenario 2: Single cell with interference

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Result 1

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Result 2

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Result 3

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Scenario 3: Multi cell

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Result 1

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Result2

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Result3

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Conclusions As user increase the delay amount increase Maximum delay value 0.22 second in all scenarios (multi cell with

hand over enable ) Proportional fairness has highest delay amount EXP/PF give much acceptable delay & PLR in all scenarios

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Recommendations

Experience the delay amount in different congested traffic model (video &FTP) in all scenarios and comparing them with VoIP result with same scheduling algorithm

Perform the simulation with different bandwidth (1.3 ,5&10 MHZ) Suggest new algorithm to minimize delay & PLR value in VoIP traffic

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Thank you ,,

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