LTE Networking

7/30/2019 LTE Networking

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LTE Networking & Capacity Coverage Analysis


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Contents

Overview of LTE Wireless Network Planning

LTE Coverage Analysis

LTE Capacity Analysis

Conclusion


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Introduce LTE into

Overall Network

IntroductionStrategy

Introduce LTE into

Key Areas

AdvantageOverall network

can receive LTE service

DisadvantageIntroducing LTE

into remote areas will waste theresource and increase operation

cost

SuggestionIt is not necessary

to introduce LTE into overall

network at the early stage of

network construction

AdvantageSave the

resource and investment

DisadvantageCan not

ensure the continuouscoverage of LTE network

fringe areas

Suggestion: Save the cost and

fit the developing situation of

high-speed data service

Strategy for Introducing LTE

ZTE serialized base stations support smooth upgrading to LTE. After network operation,

according to operator requirement or service requirement, upgrading should be gradually

conducted to support 2/3/4G co-existence in an all-round way.


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Multi-carrier: 12 sub-carriers compose one RB; multiple RBs bear the

service; overhead and service are borne and transimitted on RB

Multi-antenna Technology: Tx diversity, Rx diversity, 4-antenna or 8-

antenna beam forming and MIMO SCM technology

MCS Technology: Adaptive modulation and coding method

Variable Bandwidth: 1.4MHz, 3.0MHz, 5MHz, 10MHz, 15MHz, 20MHz1

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Characteristics of LTE

1-3 make LTE link and capacity more complicated


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LTE Capacity Planning

LTE Coverage Planning

Determine target coverage area, traffic model,

subscriber amount, coverage probability

Determine LTE networking strategy(band, time slot and time slot switch point)

LTE Network PlanningKey Nodes


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Traffic Channel Comparison in TD-SCDMA Evolution

TD-SCDMA

HSPA

LTE

Traffic channel is dedicated channel

The method of modulation and coding is fixed

Traffic channel is shared channel

Quick scheduling in time domain

Adaptive Modulation Coding

Traffic channel is shared channel

Two-dimension scheduling in time domain

Adaptive Modulation and Coding


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Contents




Conclusion


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Need to consider UL/DL coverage

requirement differences

Under the condition of equal

coverage range, UL/DL cell edge

service rate is about 1:3

LTE Networking PlanningCoverage Planning

Traffic Channel

Control ChannelFor DL, need to consider coverage ranges of PBCH,PDCCH, PCFICH, PHICH

For UL, need to consider coverage range of PUCCH


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Step1

Step2

Step3

Step5

Step6

Determine occupied bandwidth

Determine edge rate x kbps

Determine edge subscribers RB amount, n RB

Determine time slot allocation proportion

Determine required SINR as input value of receiver signal strength budget

Step4

LTE Coverage Analysis Methodology

Determine transmit/receive antenna type


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Resource occupied by cell-edge

subscribers: amount of RB

Correlate with wireless environment

& scheduling algorithm

LTE Coverage Analysis MethodologyFixed RB Amount or SINR?

Subscriber Rate

Cell-edge Subscriber Rate kbps

It can be set

Subscriber Resource SINR

Required SINR

Dynamic and adaptive environment

Fixed RB Amount

SINR can be calculated according torate requirement of cell-edgesubscriber and required amount of REfixed to bearing this rate service

Fixed Carrier-to-Interference Ratio

Because LTE is dynamic and adaptiveenvironment, its unrealistic andunreasonable to fix SINR. Furthermore,SINR division of LTE is very detailed, itsdifficult to value SINR requirement of cell-edge subscribers


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Determination of RB Amount Required by Cell-edge Subscribers

According to system simulation

calculation, under common PFscheduling, 10MHz, 10

subscribers/cell, corresponding

statistical result for the 5% worst

cell-edge subscribers is about

3.4-4.4RB. Thereby, 5RB is

reasonable for setting.

Detailed statistical resultsofdifferent scenarios are certainly

different. This value directly

correlates with scheduling

algorithm

In LTE link budget

Fixed as 5 RB (Applicable for

full buffer service under the

condition of 10MHz-20MHz

bandwidth)

3-4 RB (Applicable for thebandwidth5MHz)

System Simulation

CalculationLink Budget

Valuation

Different RB amount received by cell-edge subscribers will cause

different coverage. This value must be fixed in link budget. Otherwise,

SINR cant be obtained.


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eNodeB Allocation:

1-transmit, 2-transmit,

4-transmit, 8-transmit;

eUe Allocation:

1-receive, 2-receive, 4-receive;

Support MIMO Double-stream

Mode;

Support Beam Forming

If MIMO double-stream mode is effective while

BF mode is ineffective, eNodeB has no SFBC or

BF gain.

If BF mode is effective while MIMO double-

stream mode is ineffective, antenna allocation is 4-

transmit or 8-transmit, eNodeB has no SFBC gainbut BF gain

If neither MIMO double-stream mode nor BF(Beam Forming) is ineffective, eNodeB can use

SFBC method and it has SFBC gain

No matter MIMO double-stream mode is

effective, eUe can use diversity reception method

and it has diversity reception gain

Consideration for Multi-antennaDL


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eUe Allocation: 1-transmit,

2-transmit, 4-transmit;

eNodeB Allocation: 1-receive,2-receive, 4-receive and 8-receive;

Dont support UL MIMO;

Dont support SFBC

eNodeB diversity reception gain correlates with the amount of

receive antennas

If eNodeB is 1-receive, diversity reception gain is 0;

If eNodeB is 2-receive, diversity reception gain is 3dB;

If eNodeB is 8-receive, diversity reception gain is 8dB

No matter how many antennas are allocated for UL eUe,

theres no transmit diversity gain

(At present, the protocol doesnt support UL MIMO and

SFBC )

Consideration for Multi-antennaUL


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Assumed Conditions of Coverage Analysis

PF10MHz10/cell

SystemSimulation

Link Budget

Under common PF scheduling, 10MHz, 10 subscribers/cell

The 5% worst defined subscribers are cell-edge subscribers

Cell power amplification allocation is 43dBm

Both of LTE and WiMAX are multi-carrier systems, but power

allocations are different; for WiMAX, one more transmit antenna, one

more power; but for LTE, when antenna amount increases, the power is

shared among all the antennas

Conversion relation between RLC rate and MAC rate:

RLC rate = MAC rate90%

Receiver noise floor calculation:

Integrate on the occupied RB bandwidth

Channel overhead:

About 23-25%, roughly speaking, 3 in 14 time slots are for overhead


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Control Channel Coverage Analysis

Coverage-limited control channel is PDCCH


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Traffic Channel Coverage Analysis

For UL, traffic channel is limited. At the edge of control channel coverage, 2Tx2Rx

transmit diversity can reach 440K, 8Tx2Rx BF can reach 935K


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Analysis of Beam Forming Influence on CoverageInfluence on

LTE TDD UL

Coverage:

With the increasing

of receive antenna

amount, cell UL

coverage is graduallyexpanding

Beam forming-

Influence on LTE TDDDL

Coverage:

When double-stream

MIMO and BF are not

open, DL coverage

range is graduallyexpanding with the

increasing of transmit

or receive antenna

amount


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Conclusion

Contents


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Factors

Influencing

Capacity

B

E

C

D

A

Equipment

Performance(System Bandwidth,

Transmit Power, UE

Performance)

Environment

MIMO

Scheduling

Algorithm

Interference

Elimination

LTE Network PlanningCapacity Planning


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LTE capacity planning method cant be conducted according to R4

traffic capacity planning method

Because there are too many factors influencing capacity planning,

formula cant be used for calculation

Throughput under the conditions of various allocations and path

losses can be obtained by simulation and actual measurement

experience

In actual planning, check the form to confirm LTE capacity

according to the detailed condition of planning area

LTE Network PlanningCapacity Planning Method


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Contents




Conclusion


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Conclusion

Distributable resource is RB. It needs to be used with edge rate

requirement to confirm SINR

Multi-antenna technology is complicated. Pay attention to the

differences among transmit diversity, diversity reception and MIMO

double-stream gain

LTE often uses transmit diversity SFBC mode at cell edge and it doesntuse MIMO mode; SFBC/MIMO only exists in DL budget

Because LTE is multi-carrier system, diversity gain has evident

advantage by comparison with TD-SCDMA and other broadbandsystems; LTE has evident advantage in DL/UL by comparison with

TD-SCDMA coverage

Noise of receiver is calculated from RB amount integration; there has

been no final conclusion of UL/DL residual interference up to now; its

generally recognized that application of ICIC and other advanced

interference algorithms can greatly decrease it

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LTE Networking

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