LTE optimization

DESIGN BY:

AKRM ABDULAH RASSAM

AMAL ABDULRAHMAN HAMOUD.

SAMAR ABDULKAWE ALSHARAIE

MOHAMMED ABDULJABBAR QAID

MOHAMMED ABDUL-RAHMAN

NADA YASIN ABDULSALAM

Taiz University

Dep.COM.

Level 5

2015

LTE Network

(Coverage and capacity) Optimization

Introduction of LTE

Network Planning

LTE System Architecture

Network Optimization

INTRODUCTION OF LTE

Requirements and Targets for the LTE

Reduced delays.

Increased user data rates.

Increased cell-edge bit-rate, for uniformity of service provision.

Greater flexibility of spectrum usage.

Simplified network architecture.

Seamless mobility.

Reasonable power consumption for the mobile terminal.

Orthogonal Frequency Domain Multiple Access

(OFDMA) in downlink.

Single-Carrier Frequency Domain Multiple Access (SC-

FDMA) in uplink.

Multiple Input Multiple Output (MIMO) antennas.

Packet-Switched Radio Interface.

Technologies for the LTE

3GPP Release 8 – Freeze Date 2008

Up to 300Mbit/s downlink and 75Mbit/s uplink.

Implementation in bandwidths of 1.4, 3, 5, 10, 15 or 20MHz, to allow for

different deployment scenarios.

(OFDMA) downlink.

(SC-FDMA) uplink.

(MIMO) antennas.


Self-Organizing Network (SON) features, such as optimization of the

random access channel.

Evolved Multimedia Broadcast and Multicast Service (EMBMS)

Provides improved support for Public Warning Systems (PWS) and some

accurate positioning methods.

LTE Release and LTE-Advanced


Up to 3Gbit/s downlink and 1.5Gbit/s uplink.

Carrier Aggregation (CA), allowing the total transmission bandwidth to be

increased up to 100 MHz .

Uplink MIMO transmission for peak spectral efficiencies greater than 7.5 bps

and targeting up to 15 bps.

Downlink MIMO enhancements, targeting peak spectral efficiencies up to 30

bps.

Enhanced Inter-Cell Interference Coordination (EICIC) to improve

performance towards the edge of cells.


Enhancements to Carrier Aggregation, MIMO, relay nodes and eICIC

Introduction of new frequency bands

Coordinated multipoint transmission and reception to enable simultaneous

communication with multiple cells



New antenna techniques and advanced receivers to maximize

the potential of large cells.

Interworking between LTE and Wi-Fi or HSPDA.

Further developments of previous technologies.


Together LTE of the Evolved Universal Terrestrial Radio Access Network (E-

UTRAN) and SAE of the EPC comprise the Evolved Packet System (EPS).

EPS is the umbrella that covers both the LTE of (E-UTRAN) and the SAE of

the EPC network.

EPC and LTE under the umbrella of EPS.


The main components of LTE networks are:

User Equipment (UE)

Evolved-UTRAN (E_UTRAN)

Evolved Packet Core (EPC)

LTE network elements


User Equipment (UE)

user equipment (UE) is any device used directly by an end-user to communicate.

And it is connected to the LTE network via the RF channel through the BS that

is part of the eNB.

It can be a hand-held telephone, a laptop computer equipped with a mobile

broadband adapter, or any other device

UE handles the following tasks towards the core network:

o Mobility management , Call control and Identity management.

User Equipment connected to LTE network


Evolved-UTRAN (E_UTRAN)

The E-UTRAN is responsible for all radio-related functions, which can be

summarized as:

Radio Resource Management : This covers all functions related to the radio

bearers, such as radio bearer control, radio admission control, radio mobility

control, scheduling and dynamic allocation of resources to UEs in both uplink

and downlink.

Header Compression : This helps to ensure efficient use of the radio

interface by compressing the IP packet headers, which could otherwise

represent a significant overhead, especially for small packets such as VoIP.

Security : All data sent over the radio interface is encrypted.

Positioning : The E-UTRAN provides the necessary measurements and other

data to the E-SMLC and assists the E-SMLC in finding the UE position

Connectivity to the EPC : This consists of the signalling towards the MME

and the bearer path towards the S-GW.


Architecture of the evolved UMTS terrestrial radio access network

The eNodeBs are normally inter-connected with each other by means of an interface

known as X2, and to the EPC by means of the S1 interface.

The protocols which run between the eNodeBs and the UE are known

as the Access Stratum (AS) protocols.


Evolved Packet Core (EPC)

Evolved Packet Core is responsible for the overall control of the UE and the establishment of

the bearers. The main logical nodes of the EPC are:

PDN Gateway (P-GW).

Serving Gateway (S-GW).

Mobility Management Entity (MME).

Home Subscriber Server (HSS).

Policy Control and Charging Rules Function (PCRF).

EPC elements


P-GW(Packet Data Network- Gateway)

The (P-GW)is the EPC’s point of contact with the outside world .

Through the SGi interface,

The P-GW is responsible for IP address allocation for the UE, QoS

enforcement and flow-based charging according to rules from the

PCRF.

S-GW (Serving Gateway)

acts as a router, and forwards data between the base station and the

PDN gateway.

MME (Mobility Management Entity)

The MME is the control node, which processes the signaling between

the UE and the EPC.

The main functions supported by the MME are :

establishment, maintenance and release of the bearers.

paging subscribers in the EPS Connection Management.

the MME performs management of handovers.


PCRF (Policy Control and Charging Rules Function)

The PCRF is responsible for controlling the flow based charging

functionalities in the Policy Control Enforcement Function (PCEF), which

resides in the P-GW.

HSS (Home Subscriber Server)

The HSS contains user’s subscription data such as the EPS-subscribed QoS

profile and any access restrictions for roaming.


NETWORK PLANNING

1-COVERAGE PLANNING

LTE Radio access network planning refers to analytical approach which is

based on algorithmic formulation and focuses on the radio engineering

aspect of the planning process, i.e :

• on determining the locations.

• estimated capacity and size of the cell sites (coverage and capacity

planning).

• and assigning frequencies to them by examining the radio-wave

propagation environment and interferences among the cells.

Network Planning

LTE Access Network Dimensioning:

The target of the LTE access network dimensioning is to

estimate the required site density and site configurations for the

area of interest.

Initial LTE access network planning activities include:

radio link budget .

a coverage analysis.

cell capacity estimation.

estimation of the amount of eNB.

Coverage planning

Radio Link Budget:

Maximum allowed propagation loss gives the attenuation of the signal as it

travels from transmitted to the receiver. Path loss is converted into distance

by using appropriate propagation models. This is the distance from the base

station where the transmitter signals can be received by the users (receiver).

This distance or the radius of the cell is used to calculate the number of sites

required to cover the whole area with respect to coverage estimation.

Coverage planning

Link budget and coverage planning is calculated, for both cases UL and DL

a following the procedure steps are :

Step 1: Calculate the Max Allowed Path Loss (MAPL) for DL and UL.

Step 2: Calculate the DL and UL cell radiuses by the propagation model

equation and the MAPL.

Step 3: Determine the appropriate cell radius by balancing the DL and UL radiuses.

Step 4: Calculate the site coverage area and the required sites number.

Coverage planning

Radio Link Budget:

Propagation models:

budget among other important performance parameters. These

models are based on the frequency band, type of deployment area

(urban, rural, suburban, etc.), and type of application .

The Cost231-Hata model can be expressed by the following formula:

Coverage planning

Coverage-based site account:

For Omni-directional configuration Sites:

Coverage planning

2- CAPACITY PLANNING

Capacity planning gives an estimate of the resources needed for supporting

a specified offered traffic with a certain level of QoS

e.g.

throughput

blocking probability

Theoretical capacity of the network is limited by the number of eNodeB’s installed

in the network.

Cell capacity in LTE is impacted by several factors,

• interference level,

• packet scheduler

• supported modulation

• coding schemes.

Capacity Planning

§ The LTE Cell Capacity (Throughput) depends on:

o Cell Range (Path loss)

Channel Bandwidth (1.4 MHz... 20 MHz)

LTE Features

• MIMO :

Open/Closed Transmit diversity

it results in coverage improvement therefore, it is more suitable to be used

at the cell edge.

– Open / Closed Loop Spatial Multiplexing Spatial multiplexing on the other

hand doubles the subscriber data rate

LTE Capacity Dimensioning Process


• Scheduling:

A scheduling with support for QoS provides

for efficient scheduling of UP and CP data.

4. Cell Load: It has to be noticed that when the neighbour cell load

is decreasing the cell throughput is increasing as expected.


Fractional Frequency Reuse (FFR(

The basic idea on which the FFR schemes rely is to divide the

whole available .resources in .to two subsets or group FFR scheme

has two main classes:

Partial Frequency Reuse (PFR):

in this scheme a common frequency band is used in all sectors

with equal power to create one sub-band with a low inter-cell

interference level in each sector.


Soft Frequency Reuse (SFR):

in this scheme, each sector transmits in the whole frequency band.

However, the sector uses full power in some frequency sub-bands

while reduced power is used in the rest of the frequency band.


Cell capacity provided from the link level simulation as input to these approach

assumes that

the target date rate is #Mbps per subscriber. Since only some of the subscribers

are downloading data simultaneously, we can apply an overbooking factor. This

essentially means that the average busy hour data rate is:

Where:

Overbooking factor (OBF) is the average number of subscribers that can share a

given unit of channel

Average BH data rate per sub =𝒕𝒂𝒓𝒈𝒆𝒕 𝒅𝒂𝒕𝒂 𝒓𝒂𝒕𝒆 𝒑𝒆𝒓 𝒔𝒖𝒃

𝒐𝒗𝒆𝒓𝒃𝒐𝒐𝒌𝒊𝒏𝒈 𝒇𝒂𝒄𝒕𝒐𝒓

Data rate based approach


• The number of subscribers per site using this approach calculated

as:

# of sub per site =3cellcapacity×𝑩𝑯 𝒂𝒗𝒆𝒓𝒂𝒈𝒆 𝒍𝒐𝒂𝒅

𝑨𝒗𝒆𝒓𝒂𝒈𝒆 𝑩𝑯 𝒅𝒂𝒕𝒂 𝒓𝒂𝒕𝒆 𝒑𝒆𝒓 𝒔𝒖𝒃

• The number of sites to satisfy the traffic demand requirement for

the each subscriber calculated as:

# of site for capacity requirement = 𝑻𝒐𝒕𝒂𝒍 # 𝒐𝒇 𝒔𝒖𝒃𝒔𝒄𝒓𝒊𝒃𝒆𝒓𝒔

# 𝒐𝒇 𝒔𝒖𝒃 𝒑𝒆𝒓 𝒔𝒊𝒕𝒆


LTE(RF) OPTIMIZATION

LTE(RF) optimization

• To meet customers' requirements for high-quality

networks, LTE trial networks must be optimized

during and after project implementation.

• Radio frequency (RF) optimization is necessary in

the entire optimization process.

What is optimization:Optimization is the fine-tuning of a nominal cell plan to a real

environment.

Objective:• The design criteria in regards to coverage, capacity and quality.

• The standards defined by local government authority.


Need for optimization

• Perceived reduction in network quality.• Indications from network performance monitoring.

• Subscriber's experience of using the network.

• Maximizing the use of existing infrastructure.

.

• Introduction of new services.




Network Optimization Methods


Thank you

Date post:	16-Jul-2015
Category:	Engineering
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LTE optimization

Engineering