11 RA4120BEN20GLA0 LTE Deployment Scenarios v03

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LTE Deployment Scenarios

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1 © Nokia Siemens Networks RA4120BEN20GLA0

LTE RPESSLTE Deployment Scenarios

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Nokia Siemens Networks Academy

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Module Objectives

After completing this module, the participant should be able to:

• Identify different solutions to provide LTE Coverage

• Discuss alternatives to improve the indoor coverage

• Understand the concept of Microcell

• Describe at an overview level the requirements for Co-Siting isolation & configuration

• Recall the concepts of Tracking Area, eNode B identifier, neighbour cell and its planning principles.

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Module Contents

• Macrocells

• Indoor Solutions

• Microcells

• Co-Siting Bands

• Co-Planning− Tracking Area Planning− Physical Layer Cell Identity Planning− eNode B and Cell Identity Planning− Neighbour Planning

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Introduction

Macrocells• provide coverage and capacity across wide areas

• Standard deployment solution

Indoor solutions• improve coverage when indoor macrocell coverage is weak

• provide high capacity solutions

Microcells• serve traffic hotspots

• provide coverage when macrocell sites are not available

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Macrocell with Flexi Multiradio BTS

• Flexi RF modules can be located adjacent to the Flexi System module (Picture on the left)

• But Flexi RF modules can also be located adjacent to the antenna to create a feeder-less design (optical connection between System Module and RF Module)

• Tower Mounted Amplifier (TMA) / Mast Head Amplifier (MHA) can be used to compensate for feeder losses in the uplink direction

• Antennas can be mounted according to the site design, e.g. roof-top, mast, side of buildingOptional

TMA/MHA

Optional AC/DC with Battery Backup

System Module

1 or 2 RF Modules

RF Connection

TMA not meaningful, if RF Module is close to antenna

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LTE 2600 can be deployed on UMTS 2100MHz grid(figures applicable to Urban Deployment)

Uplink

142.8dB 140.2dB

LTE

UMTS

142.9dB 140.8dB

LTE

UMTS

Downlink

Conclusion

Delta between max. allowable pathloss values:

2.1 dB in downlink benefit of LTE

2.6 dB in uplink benefit of LTE

1.09km1.08km 1.17km 1.22km

Delta between outdoor cell range values:

DL:LTE cell range nearly identical to UMTS

UL:LTE cell range nearly identical to UMTS

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Indoor Solutions

• Indoor solutions can be based upon the Flexi BTS connected to a Distributed Antenna System (DAS)

• Passive DAS for small and moderate sized indoor areas

• Active DAS for large indoor areas

• Passive and Active DAS connected to a Flexi BTS are able to provide both coverage and capacity. Multiple sectors can be licensed to increase capacity

• Repeaters can also be used to extend outdoor coverage across an indoor area

• Historically, indoor solutions have been designed with single transmit and receive paths. This excludes the possibility of uplink receive diversity and MIMO

• Indoor solution design requires a set of planning guidelines to ensure that proven approaches are used in a consistent manner

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Minimum Coupling Loss (MCL)

• MCL represents the minimum allowed link loss between the UE and Node B cabinet antenna connector

• The MCL should be sufficient to ensure that the BTS does not become desensitised when a UE is physically close to an antenna

• The MCL should also be sufficient to ensure that the UE does not receive more downlink power than it is capable of receiving when it is physically close to an antenna

• The MCL requirement depends upon the thermal noise floor of the Node B receiver, i.e. dependant upon receiver bandwidth and Noise Figure

• Assuming a 43 dBm transmit power from the LTE BTS means that an MCL of 68 dB is required to ensure that UE do not receive more than -25 dBm

Comparing the uplink and downlink MCL requirements indicates that the uplink requirement dominates: an MCL of between 70 and 75 dB is necessary

(from 3GPP TS 36.101)

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Antenna Placement

• Indoor solution design includes making decisions regarding the location of each remote antenna

• Antenna placement should account for:

Service and Reference Signal link budget requirements

Leakage requirements

Distribution of interference from the Macrocell layer

Minimum Coupling Loss (MCL) requirements

Distribution of UE and the associated traffic

Sectorisation Strategy

• Indoor solutions may be configured with single or multiple sectors

• The level of sectorisation should be defined by the capacity requirements

• This requires a definition of the traffic expectation

• Sectorisation should be planned to achieve sufficient isolation between sectors

• Sectorisation in multi-storey buildings can take advantage of the inter-floor isolation

• Overlap is required to allow time for inter-sector handover

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Selection between Active and Passive DAS• Two general approaches can be adopted:

passive DAS should be able to maintain ~15 dBm of downlink transmit power at each antenna. If not, then active DAS should be selected

rule-of-thumb based upon the number of antennas, e.g. if the antenna requirement is above 5 then select an active DAS

• In general, active DAS are easier to sectorise subsequent to initial deployment because it is relatively easy to lay spare fibre optic during installation

RF Carrier Assignment

• RF carrier used for indoor solutions can be the same as that used for the outdoor macrocell

• Unlikely to be practical to dedicate and RF carrier to indoor solutions when wide bandwidths are allocated to LTE

• Important to ensure that indoor solution has dominance so the number of antennas required may increase if macrocell signal is relatively strong indoors

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Verification of Existing Coverage

• Indoor solution may be proposed for coverage or capacity reasons

• Possible that macrocell layer already provides coverage while indoor solution is required for capacity

• Important that indoor solution dominated over macrocell to avoid loading the macrocell layer

• Macrocell measurements should be recorded prior to indoor solution design

Leakage Requirements

• Requirement to minimise leakage from indoor solution to the outdoor environment

• If leakage is not limited then UE in the outdoor environment could camp and establish connections upon the indoor solution

• An example approach is that the indoor solution Reference Signal Received Power (RSRP) should not exceed –125 dBm at a distance of 20 m from the building

• This absolute power threshold may be translated into a link loss based threshold

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Mobility with Macrocell Layer

Indoor Solution Reference Signal EIRP

MS approaching indoor solution

Macrocell Reference Signal EIRP

Potential interference

• LTE handovers are based upon Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ)

• Handover and cell re-selection boundaries between macrocell and indoor solution will depend upon:

relative transmit powers of the indoor solution and macrocell

measurement offsets defined for each adjacency

• If handover boundary is too close to the indoor solution then there is a danger that the indoor solution experiences uplink interference from UE connected to macrocells

• Measurement offsets should be applied with care because they can result in MS not being connected to the ‘best’ cell

• Indoor solution handover areas are usually located around the building entrances

• Tall buildings may have stronger macrocell coverage across the upper floors, potentially allowing MS to handover onto macrocells inside the building

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Microcells

• Microcells can be used to serve traffic hotspots

• A microcell can be categorised as a Node B which has outdoor, below rooftop antenna placement

• Like macrocell, a microcell Node B is a Flexi System Module equipped with a Flexi RF module

• The isolation provided by neighbouring buildings limits both coverage and inter-cell interference

Microcell based upon Flexi RF Module

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Microcell Link Budget

Macrocell antennaMicrocell antenna

• Microcell antennas typically have a lower gain than macrocell antennas e.g. 12 dBi

• Lower gain corresponds to less directivity and an increase in vertical beamwidth

• Feeders are typically short but may have a smaller diameter than that used for macrocells –smaller diameter allows a tighter bending radius for easier installation

• Microcells are typically introduced for capacity so should be planned assuming a relatively high cell load for both UL & DL.

Antenna Gain 12 dBi

Feeder Loss 1 dB

Uplink Load 80 %

Example Parameters

for Microcell Link Budget

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Microcell Sectorisation

• Sectorisation of LTE microcells is unlikely to be common because it’s difficult to achieve sufficient isolation between sectors

• Sectorised GSM microcells benefit from having different RF carriers assigned to each sector

• The high quantity of scattering tends to mean that sectors have very similar coverage areas

• Antenna direction may not have a very large impact as a result of the scattering

Example Microcell Propagation for two cells with different antenna directions

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Microcell RF Carriers

• LTE microcells are likely to be configured using the same RF carrier as the macrocelllayer

• Wide channel bandwidth results in a requirement to use a frequency re-use factor of 1

• Sharing the same RF carrier between macro and micro layers potentially results in a low isolation

• Most likely to be true when microcells are introduced for capacity within an area of macrocell coverage

• Requirement to ensure that microcells are dominant across their target coverage area

• Sharing the same RF carrier allows intra-frequency hard handovers between the macro and micro layers

• Potential requirement to tune mobility parameters to account for differences between the macro and micro downlink transmit powers

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Operating Bands Specified by 3GPP

Extract from 3GPP TS 36.104

Extract from 3GPP TS 25.104

• LTE operating bands are similar to those for UMTS

• This implies there will be a requirement for LTE to share operating bands with UMTS, i.e. to operate in adjacent spectrum

• In the case of co-siting for FDD RATs, the duplex spacing provides isolation in the frequency domain, i.e. the BTS transmit band is relatively distant from the BTS receive band

UMTS FDD Operating Bands

LTE FDD Operating Bands (a part of the complete list)

RL10 Flexi RF Module SupportRL20 Flexi RF Module Support

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Introduction

• Co-Planning activities are those for which re-use from other network planning projects

may be applied

• Experience gained while planning 2G and 3G networks can be used to improve the

efficiency with which LTE networks can be planned

• Potential activities for co-planning are:

• 3G routing area planning with LTE tracking area planning

• 3G Node B identity planning with LTE eNode B identity planning

• 3G neighbour list planning with LTE neighbour list planning

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Background (I)

• Tracking areas are used for EPS Mobility Management (EMM)

• Paging messages are broadcast across the tracking areas within which the UE is registered

• Each eNode B can contain cells belonging to different tracking areas

• Each cell can belong to several tracking area

• A tracking area can be shared by multiple MME

• Tracking Area Identity (TAI)

• Constructed from the Mobile Country Code (MCC), Mobile Network Code (MNC) and TAC (Tracking Area Code)

• The TAC, MCC and MNC are broadcast within SIB 1

S1 Application Protocol Paging Message extracted from 3GPP TS 36.413

Evolved Packet System

Tracking areas are the equivalent of Location Areas and Routing Areas for LTE

EMM Registered EMM Deregistered: Successful Attach and Tracking Area Update (TAU) procedures lead to transition to EMM-REGISTERED

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Background (II)

• The normal tracking area updating procedure is used when a UE moves into a tracking area within which it is not registered

• The periodic tracking area updating procedure is used to periodically notify the availability of the UE to the network (based upon T3412)

• Tracking area updates are also used for

• registration during inter-system changes

• MME load balancingFurther details in 3GPP TS 24.301

• Large tracking areas result in

• Increased paging load

• Reduced requirement for tracking area updates resulting from mobility

MME load balancing: Since TA can belong to more than one MME, if one MME is loaded then it is possible to send the paging message through other MMEs

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Planning Guidelines

• Tracking areas should be planned to be relatively large (100 eNodeB)rather than relatively small

• Their size should be reduced subsequently if the paging load becomes high

• Existing 2G and 3G location area and routing area boundaries should be used as a basis for defining LTE tracking area boundaries

• Tracking areas should not run close to and parallel to major roads nor railways. Likewise, boundaries should not traverse dense subscriber areas

• Cells which are located at a tracking area boundary and which experience large numbers of updates should be monitored to evaluate the impact of the update procedures

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Introduction

• There are 504 unique Physical Layer Cell Identities

• Organised in 168 groups of 3

• NID1 in the range 0 to 167 represents the Physical Layer Cell Identity group

• NID2 in the range 0 to 2 represents the identity within the group

• Physical Layer Cell Identity = (3 × NID1) + NID2

• NID2 defines the Primary Synchronisation Signal (PSS) sequence

• NID1 defines the Secondary Synchronisation Signal (SSS) sequence

• The Physical Layer Cell Identity has an impact upon the allocation of resource elements to the reference signal and the set of physical channels

Allocation pattern repeats every 6th

Physical Layer Cell Identity

Resource element allocation to the Reference Signal

0 to 503LNCELphyCellId

RangeObjectParameter

Compared with 512 scrambling codes in 3G (64 groups of 8)

First: PSS and SSS signals:

The PSS is generated out of 3 different sequences – each of these sequences indicates one Physical Layer Cell Identity

The SSS is generated out of 168 sequences – each of these sequences indicates one Physical Layer Cell Identity Group

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Planning (I)

• The allocation of physical layer cell identities is analogous to scrambling code planning for UMTS

• The isolation between cells which are assigned the same physical layer cell identity should be maximised

• The isolation between cells which are assigned the same physical layer cell identity should be sufficiently great to ensure that UE never simultaneously receive the same identity from more than a single cell.

Id = 5

Id = 4

Id = 3

Id = 11

Id = 10

Id = 9

Id = 8

Id = 7

Id = 6

Id = 2

Id = 1

Id = 0

Example Physical Layer Cell Identity Plan

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Planning (II)

• Specific physical layer cell identities can be excluded from the plan to allow for future network expansion or the introduction of Home eNodeB(Femto)

• If there is a possibility that the level of sectorization is going to be increased from 3 to 6 then every second group of identities could be allocated within the initial plan. This would allow eNodeB to be allocated identities from two adjacent groups when the number of cells is increased from 3 to 6

• There should be some level of co-ordination across international borders when allocating physical layer cell identities. This will help to avoid operators allocating the same identity to cells on the same RF carrier and in neighbouring geographic areas

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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eNode B Identifier

• The Global eNode B Identifier is used to identify eNode B globally

• It is constructed from the MCC, MNC and eNode B Identifier (eNB-Id)

• The eNB-Id is used to identify eNB within a PLMN

• The eNB-Id can have a lengths of

• Short (20 bits) allowing– 256 cells to be addressed per eNB

– 1 048 576 eNB per PLMN

• Long (28 bits) allowing– 1 cell to be addressed per eNB

– 268 435 456 eNB per PLMN

• The short eNB-ID is appropriate for macrocell networks which include more than a single cell per eNB

• The long eNB-ID is appropriate for picocell and femto networks which are based upon large numbers of Node B with only a single cell per Node B

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Cell Identifier

• The E-UTRAN Cell Global Identifier (ECGI) is used to identify cells globally

• The ECGI is constructed from the MCC, MNC and E-UTRAN Cell Identifier (ECI)

• The ECI is used to identify cells within a PLMN

• It has a length of 28 bits and contains the eNode B Identifier

• It is only necessary to configure an ECI when a short eNB-Id is used

• The ECI, MCC and MNC are broadcast within SIB 1

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Module Contents

• Macrocells


• Microcells

• Co-Siting Bands


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Background

• LTE mobility does not rely upon neighbour lists

• UE are responsible for identifying neighbouring cells

• This effectively removes the requirement for neighbour list planning

• However, the UE can be provided with:

• neighbour cell specific measurement offsets, e.g. to make a specific neighbour appear more attractive

• RF carriers upon which to search for neighbours

• Mobility information can be provided for:

• E-UTRAN Intra-frequency

• E-UTRAN Inter-frequency

• UTRAN inter-RAT

• GERAN inter-RAT

• CDMA200 inter-RAT

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Automated neighbor relation (ANR) configuration

• Neighbour relations are important as wrong neighbour definitions cause HO failures and dropped calls

• Self configuration of relations avoids manual planning & maintenance

ANR covers 4 steps:1) Neighbour cell discovery

2) Neighbour Site’s X2 transport configuration discovery (i.e. Neighbour Site IP@)

3) X2 Connection Set-up with neighbour cell configuration update

4) ANR Optimization

• The scope within ANR is to establish an X2 connection between source and target nodes and for that it is necessary that source eNB knows the target eNB IP@

• How the source eNB gets the IP@ differentiates the ANR features:– LTE Automatic Neighbour Cell Configuration (RL09)

– Central ANR (RL10)

– ANR (RL20)

– ANR- Fully UE based (RL30)

NetAct Optimizer supervises all registered cell relations between neighbouring LTE cells if they are still valid and reliable candidates to be a hand over destination. When the outcome results in an inefficient neighbour relation the according cell relation may be blacklisted for handover (RL20)

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MME

3GPP ANR configuration principle

SiteeNB - A

NeighborSite

eNB - B

New cell discovered

New cell identifiedby ECGI

CM

X2 Setup : IPsec, SCTP, X2-AP [site & cell info]

UEconnected

S1 : Request X2 Transport Configuration (ECGI)

S1: Request X2 Transport Configuration

relaysrequest

S1: Respond X2 Transport Configuration (IP@)

S1 : Respond X2 Transport Configuration (IP@)

CM

relaysresponse

Add Site & Cellparameter of

eNB-A CM CM

Add Site & CellParameter of

eNB-B

Neighbor Cell Tables in both eNB updated

SCTP: Stream Control Transmission Protocol

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LTE ANR

Automated planning: NO configuration of any neighbor cell attributes

•NetAct Optimizer and Configurator create the list of potential neighbour cells and related IP connectivity information

Feature ID: LTE492

RL20

•When UE reports an unknown PCI the source eNB looks for that PCI in look-up tables to find the IP@ of the site hosting the PCI reported

UEs measurements taken into account to trigger the X2 connection

•Once known target eNB IP@ the X2 connection is established and information between neighbours is exchanged

Advantage:

•Works with any UE (no need to report ECGI)

•No neighbour site planning required

The resolution of PCI to IP-connectivity information is done by means of a PCI/RF/IP@ look-up table stored at the eNB, provided by O&M-configuration (NetAct Optimizer, NetAct Configurator).

NetAct just provides in advance the mapping of IP@ to Physical Cell Ids.

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E-UTRAN Intra-Frequency & CDMA2000 Inter-RAT --- supported in RL20

• It’s not necessary for the network to broadcast any intra-frequency neighbour cell information, while it’s necessary to broadcast for UE to search CDMA2000 neighbour carriers (SIB8).

• Measurement offsets can be specified for up to 16 specific E-UTRAN Intra-Frequency cells if desired

• Specific E-UTRAN Intra-Frequency cells can also be blacklisted.

E-UTRAN Inter-Frequency & UTRAN/GERAN Inter-RAT --- not supported in RL20

• The network broadcasts the RF carriers upon which the UE should search for inter-frequency / UTRAN inter-RAT neighbours.

• Measurement offsets can be specified for both specific RF carriers and specific cells (not applicable for UTRAN/GERAN neighbours).

•For UTRAN side, RU20 supports broadcasting LTE RF carriers information (as individual neighbour

information is not needed) in SIB19 to enable 3G4G cell reselection,, .

11 RA4120BEN20GLA0 LTE Deployment Scenarios v03

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