dualband

Motorola Confidential Proprietary

Dual BandAshwin Dhareshwar


Overview

• Key differences• Implementation considerations• Antenna Choice• Motorola Specific features


Key Difference (GSM900 - GSM1800)

• A little physics– Diffraction loss and Penetration loss higher in 1800 MHz band

– 6dB minimal theoretical difference (see: Frii’s transmission formula)

• Path loss difference - on-street– Path loss at 1800MHz is typically 6 - 12 dB higher

– Most probable difference in urban environment: 8 dB

– Difference is nearly distance-independent (fixed), in typical urban cells ( i.e. constant offset in “ loss per length unit ” )

– Actual difference depends on site configuration like antenna height and antenna characteristics

– Cell radius at 1800 MHz typically 50% less compared to 900 MHz


Key Difference (GSM900 - GSM1800)

• Path loss difference - in-building– Additional attenuation at 1800MHz when penetrating into buildings– High dependency of penetration loss on building structure, window

size, floor height, angle of incident waves and floor level

• Empirical measurement results– Building penetration loss at 900MHz:

5dB to 25dB– Average additional path loss at 1800MHz:

7dB, 4dB standard deviation


On-Street Propagation Characteristics R

ecei

ve le

vel (

dB

)

Log (Distance)

LOS dominates Non-LOS dominates~ 150m - 300m

GSM 900

GSM 1800

>8 dB

6 - 8 dB

in typical urban cells:• difference is nearly distance-independent

prerequisite: • same ERP on both bands• equal antenna pattern


Pathloss Difference 900MHz vs. 1800MHz - Measurement Results

Average difference: 7.8dB ~ 6dB standard deviation

GSM 900

GSM 1800


Projection of Vertical Antenna Pattern

radiated power as function of different vertical patternK741344 dual band antenna

2

4

6

8

10

12

14

16

0 50 100 150 200 250 300 350

distance (m)

gai

n (

dB

d)

vertical pattern@900MHz

vertical pattern@1800MHz

weaker 1800 coverage next to siteweaker 1800 coverage next to site

higher gain in main beamhigher gain in main beamdirection at 1800direction at 1800

K741344 900 1800horizontal BW (deg) 65 62

vertical BW 7 6.5Gain 15.5 16

(deg)(deg)


Key Factors Influencing Propagation

Theoretical difference 1800MHz vs. 900MHzAbout 8 dB more path loss at 1800MHz for on street coverage

Diffraction loss and penetration loss is higher at 1800 MHz Additional attenuation when penetrating into buildings, variation of 3dB

to 15dB measured (average 7dB, st.dev 4dB)

Practical difference in coverage Difference can be compensated with a higher ERP at the 1800 band

Antenna height has high impact on difference in coverage (Diffraction -the main propagation mechanism - becomes less

important)Antenna pattern - especially vertical pattern - has high impact on

difference in coverageDifference raises with raising cell radius


Cell Radius at 900MHz and 1800MHz

Estimated cell radius for contiguous in building coverage

based on Hata Model / COST 231 + Hata Model, ( refer to GSM 03.30) and measurements carried out in Vienna

Environment

cell radius cell radius

@900MHz @1800MHz

rural 5150 m 2010 m

urban 800 m 250 m

ERP 55dBm

MS Rx sensitivity -102 / -100dBm

penetration loss 900MHz 20dB

additional loss 1800MHz 5dB

fading margin 6dB

interference margin 5dB

antenna / body loss 3dB

max. path loss 123dB / 118dB

antenna height: 30 m

level in build. -88dBm / -86dBm

level on street -68dBm / -61dBm


Key factors Influencing Coverage

Signal Strength

basic cell radiusextended cell radius by increased Tx power

and improved Rx sensitivity

Distance

increasedTx power

improvedSensitivity

transmit power base station sensitivity

•antenna height•antenna gain - vertical pattern•cell radius

•base station transmit power •base station sensitivity


Overview

2. Upgrading a GSM900 Network to a Dual-Band Network– Implementation Decisions– Link Balance– Mast Head Amplifiers (MHA)– Antenna Solutions– Site Configurations– RF Feeder Cables


• GSM 900 sites can be used to locate new GSM 1800 sites• Cell coverage of downtown urban areas (e.g. cell radius ~ 300m)

can be adequately covered by co-located GSM 900 and GSM 1800 BTS sites• Coverage of GSM 900 cell radius > 300m requires additional GSM 900/1800

BTS sites

• GSM 900 sites can be used to locate new GSM 1800 sites• Cell coverage of downtown urban areas (e.g. cell radius ~ 300m)

can be adequately covered by co-located GSM 900 and GSM 1800 BTS sites• Coverage of GSM 900 cell radius > 300m requires additional GSM 900/1800

BTS sites

Multi-band Implementation

Contiguous vs. non-contiguous“ hot-spot” coverage

contiguousGSM1800 cells GSM 900 cells

non-contiguousGSM1800 cells

• Capacity properly geographical distributed

• Overlapping with current network layer• Ideally all the resources available to all

subscribers for better efficiency





• Best implementation strategy: all macro sites are co-located Dual Band sites with cell radii <300m in downtown urban areas

• Minimum optimisation effort, Handover planning, same database setting for all sites

• Best implementation strategy: all macro sites are co-located Dual Band sites with cell radii <300m in downtown urban areas

• Minimum optimisation effort, Handover planning, same database setting for all sites

Multi-band Implementation

Contiguous vs. non-contiguous“ hot-spot” coverage

contiguousGSM1800 cells GSM 900 cells

non-contiguousGSM1800 cells








Multi-band Implementation Decisions

• Network management strategy for GSM1800– coverage driven or capacity driven– 1800 coverage should be adjusted based on 900 coverage for

use of software features like single BCCH– Site configuration decisions

• separated antennae vs. dual band antennae• diversity technique• single or separated feeders• use of Mast Head Amplifiers (Tower Top Amplifiers)

– Fixed frequency plan or SFH - Synthesiser Frequency Hopping


Multi-band Implementation Decisions

• From implementation decision follows– Coverage conditions for chosen configuration– Principle database parameter settings

• Prerequisites– A balanced link for chosen configuration


Link Balance - A Winning Coverage Formula

Balanced Link:

• all available BTS resources used• optimised cell coverage• high quality of network

performance ensured• good handover and call set-up

performance ensured

Balanced Link:

• all available BTS resources used• optimised cell coverage• high quality of network

performance ensured• good handover and call set-up

performance ensured

Rx

Cell radius

Tx

Rx

Cell radius

Tx


Motorola GSM1800 Technology

Transmitting power:

• 32 Watts (45.1dBm) at top of BTS rack

• The highest Tx power on GSM1800 market

Transmitting power:

• 32 Watts (45.1dBm) at top of BTS rack

• The highest Tx power on GSM1800 market

BTS system sensitivity (at antenna connector):Motorola BTS with MHA: > -110 dBm At least 6dB improvement compared with ETSI

Motorola BTS without MHA: -108.5 dBm4.5dB improvement compared with ETSI

Under all GSM specified channel conditionsMotorola production standard - no selection

BTS system sensitivity (at antenna connector):Motorola BTS with MHA: > -110 dBm At least 6dB improvement compared with ETSI

Motorola BTS without MHA: -108.5 dBm4.5dB improvement compared with ETSI

Under all GSM specified channel conditionsMotorola production standard - no selection


Why Do We Need Mast Head Amplifier ?

• Without MHABTS System Sensitivity depends on L

• With MHABTS System Sensitivity isalmost independent of L

L = feeder loss

S/N

S/N

Use of MHA overcomes the deterioration in thesystem sensitivity due to lengthy RF feeder cables


Benefits of Mast Head Amplifier

More Air TimeMore Air Time

reduced interferencebetter uplink qualityincreased capacity

low handset transmitting power

longer battery life

high signal-to-noise ratio

high voice qualityovercomes high feeder loss


A comparison with and without MHA

with MHA

without MHA

Uplink Rx Quality0 1 2 3 4 5 6 7

80

85

90

95

100

Pro

babi

lity

( %

)Measured Call Quality cumulative distribution - CDF


Antenna Recommendations

• Preferred antennas:– 65 ° sector antennas– Small vertical beamwidth <7°– High front-to-back ratio >30 dB– Maximum gain– Low upper sidelobe (high sidelobe suppression) typ. -20 dB maximum– Dual-polarisation (slant +45°/45°, isolation >30 dB)– Electrical downtilt <10°


Dual-band vs. separated single-band antennae

• Separated single-band antennae– different settings for GSM900 and GSM1800 antennae possible

– high degree of optimisation parameters– separated feeders to avoid 50% more loss at 1800MHz

– keep space on mast for 3rd generation antennae

– no need to re-plan well-optimized GSM900 network

• Dual-band antenna solutions– one setting suites both layers due to fairly fixed propagation offset– ease optimisation work due to fairly fixed propagation offset

– cheaper single feeder solution - especially for high mast sites

– no additional mast space required– newest antenna technology on the masts

– replacing old single band antennae with obsolete radiation characteristics - broad vertical pattern


Horizonmacro Configuration 2 - 2 - 2 with TDF Twin Duplexed Filter

1 sector:single band GSM 1800x polarised antenna+45° / -45°polarisation diversity

Tx1 Tx2

Rx1a,Rx2a Rx1b,Rx2b

S U R F LNA, switch

feeder 7/8” or 1 5/8“

CTU2

TDF

CTU1

Tx/RxTDF: Twin Duplexed

Bandpass Filter

indoor or outdoor Horizonmacro

max.Tx power: ( TOC)

EGSM 900

GSM 1800

46.0dBm/40W

45.1dBm/32W

configuration: 2 - 2 - 2

air combining

TOC: Top of Cabinet

Rx1/Rx2


Horizonmacro Configuration 4 - 4 - 4 with DCF Duplexed Combining Filter

max.Tx power: ( TOC)

EGSM 900

GSM 1800

43.0dBm/20W

42.1dBm/16W

configuration: 4 - 4 - 4

hybrid + air combining

1 sector:single band GSM 900/1800x polarised antenna+45° / -45°polarisation diversity

Tx1 Tx2

Rx1a-Rx4a Rx1b-Rx4b

S U R F LNA, switch

Rx1b/Rx2b

feeder 7/8” or 1 5/8“

Tx4Tx3

CTU3 CTU4

DCF

CTU1 CTU2

DCF

Tx/Rx Tx/Rx

Rx1a/Rx2a

DCF: Duplexed CombiningBandpass Filter

TOC: Top of Cabinet

indoor or outdoor Horizonmacro


1 sector:dual-band GSM 900/1800x polarised 4 port antenna

+45° / -45°polarisation diversity

GSM 900/1800indoor or outdoor

Horizonmacro

900

1800

Tx/Rx Rx Rx

GSM 900/1800indoor or outdoor

Horizonmacro

dual banddiplexer

dual banddiplexer

dual banddiplexer

dual banddiplexer

feeder

900 18009001800

feeder

Tx/Rx

dual-band diplexers:

•typical insertion loss: ~0.2dB

•internal or external type(antenna or BTS)

•interband isolation: ~60dB

Horizonmacro Dual-band4 port configuration, single feeder


Horizonmacro Dual-band4 port configuration, separated feeder



GSM 1800indoor or outdoor

Horizonmacro

900

1800

Tx/Rx Rx Rx


Horizonmacro

separated feederGSM 900: 7/8”

GSM 1800: 1 5/8”

Tx/Rx


Horizonmacro Dual-band2 port configuration, single feeder



dual-band diplexers:

• typical insertion loss: ~0.2dB

•interband isolation: ~40dB

900/1800


Horizonmacro

dual banddiplexer

feeder

dual banddiplexer

Tx/Rx Rx


Horizonmacro

Tx/Rx Rx


Multi-carrier, air + hybrid combining with dual- and single-band antennae

Dual-band antenna - air combining•2 GSM1800 carriers with air combining•Dual-band diplexers for common feeder sharing

Single-band GSM1800 antenna air- and hybrid combining

•2 GSM1800 carriers with air combining•Includes MHA in the Rx path

900 MHz

-45° +45°

1800 MHz

-45° +45°

900 1800

+45°

1800 MHz

-45° +45°

Antenna A

Antenna B

+45°900 1800

-45°900 1800

900 BTS 1800 BTS

DX

Rx Tx

DC circuits

Antenna B

2x Mast Heads

900 1800

+45°

DX

Rx TxTx Tx

DX

Rx TxRx

Antenna A: Dual Band antenna, 2 additional GSM1800 carriers with air combining, integrated diplexer to allow the sharing of common feeders.

Antenna B: second antenna, single band GSM1800, air combining for 2 GSM1800 carriers, includes MHA in the RX path and provides polarisation diversity.(in future also GSM1800 + UMTS dual band antenna system possible)


Possible rules to select proper feeder:– GSM900 cells with 7/8” feeder, GSM1800 cells with 15/8” feeder– all cells with 7/8” feeder - when feeder loss for 1800 cells will be higher

than e.g. 3dB thicker cables will be used– all cells with 7/8” feeder - for GSM1800 cells with high feeder loss

Masthead Amp’s are used

Feeders

~ 50% more loss at GSM1800

Make

BrandModel Size dB/100m

900MHzdB/100m 1800MHz

Impedance Max f (MHz) Bend radius(mm)

Weight(Kg)

EUPEN 5228 7/8" 3.93 5.92 50 5300 120 0.59

EUPEN 5438 1 5/8" 2.41 3.71 50 2800 300 1,50

Attenuation


Dual-Band Coverage Planning

Optimisation process:

• Comparing predictions of appropriate GSM900 and GSM1800 cells for in-building coverage level(e.g. -68 dBm at 900Mhz / -61 dBm at 1800MHz)

• Adjusting GSM1800 antenna tilts to obtain similar footprint compared to the appropriate GSM900 cell– Good overlapping needed to achieve efficient traffic relief on

GSM900– Supports introduction of new multi-band features like co-incident

multi-band handover or single BCCH• Same coverage conditions (except fairly fixed offset) can be

achieved easily with dual band antennas


Example of a Dual Band System

•Planning goal•minimised interference•increased in-building penetration in urban environment

•Site configuration• maximum 2 air combined carriers at 1800• maximum 4 carriers at 900, one or two combining stages• higher ERP at 1800

•Antenna solution• separated cross polarised antennae• 1800 antennae mounted higher than 900 antennae,

spacing between antennae approx. 1m

•Feeders• separated feeders (7/8” - 1 5/8”) to reduce attenuation of 1800 signal


Example - GSM900 Coverage

> -62 dBm

> -68 dBm

> -80 dBm

> -90 dBm


Example - GSM1800 Coverage

> -62 dBm

> -68 dBm

> -80 dBm

> -90 dBm


Example - Coverage statistics

• Coverage statistics for GSM900 and GSM1800 layer

system level [dBm] area [km2]% of

area

(415km2)

GSM 900 -68 326,24 78,61%

GSM1800 -68 292,47 70,47%

1800 coverage / 900 coverage 89,65%


Multi-Band Frequency Planning

• Multi-band operation– Taking advantage of wide spectrum– Taking advantage of wide separation of frequency bands

• Wide spectrum– Frequency hopping is more effective– High call quality and simplified planning– Robust frequency reuse plan can be used for difficult terrain

• Wide separation– Ease of multi layer-frequency planning for microcellular or ‘hot

spot’ solutions

• High capacity and performance gain due to BSS features like - single BCCH - or - coincident handover -


Traffic Management


Idle Mode Control

To Favor GSM1800 Selection/Reselection• RxLev_Access_Min (C1)• Penalty Offset (C2)• Penalty Time (C2)• Cell_Reselection_Hysteresis• Seperate BA List


Multiband Reporting

• Multiband Reporting parameter instructs DB mobiles to report a certain number of neighbor cells of each band in each measurement report.

• Multiband_Reporting is an add_cell element that it is per-cell basis.

• Multiband_Reporting has ability to control frequencies reported by DB mobiles in dedicated mode.

• Multiband Reporting information is broadcasted through System Information in dedicated mode.


Multiband Reporting Modes

• Set to 0any 6 strongest cells irrespective of band.

• Set to 11 strongest on each band; followed by the strongest remaining 4 irrespective of band.

• Set to 22 strongest on each band; followed by the strongest remaining 2 cells irrespective of band.

• Set to 33 strongest on each band.


Band Preference Mode

• Motorola-specific functionality designed to allow flexible measure of control over traffic bias between layers.

• Allows operator to encourage/discourage handovers and call setups on the various layers as appropriate.

• Effectiveness increases with increasing availability of dual band-capable traffic.

• Maximize GSM1800 layer’s traffic density by using Band Preference Mode and Motorola MicrocellularHandover Algorithms.


BPM = 0

• Default operation - no band preference expressed

• Multiband handovers due to normal RF causes (PBGT, RXQUAL) can still occur


BPM = 1

• Attempt handover to strongest preferred band neighbour on SDCCH - TCH assignment

• If unable to handover to preferred band TCH, cancel band preference bias for the lifetime of the currentconnection

• Multiband handovers due to normal radio reasons may still occur


BPM = 2

• Do not invoke band changes on SDCCH - TCH assignment

• Attempt to go to strongest preferred band neighbour when normal radio reason (or congestion relief) handover required

• Preferred band neighbours take priority in the neighbour list


BPM = 3


• Attempt to go to strongest preferred band neighbour when normal radio reason (or congestion relief) handover required

• Preferred band neighbours take priority in the neighbour list


BPM = 4


• As soon as possible after TCH assignment, attempt to handover to a preferred band channel

• For normal radio reason handover, also prioritise preferred band neighbours


BPM = 5

• Attempt to hand to preferred band at SDCCH - TCH assignment

• As soon as possible after TCH assignment, attempt to handover to a preferred band channel

• For normal radio reason handover, also prioritise preferred band neighbours

• This is a combination of BPM 1,2 and 4


BPM = 6

• Invoke the operation “attempt to hand to preferred band at SDCCH - TCH assignment “ only after the cell has become congested

• If not possible, after assignment on the non preferred band, attempt to handover this MS to a preferred band neighbour ASAP

• This is like condition 5, but triggered only when the cell is congested


BPM Summary

Handover to strongest reported neighbour for normalradio resource reasons (Default).TCH assignment to preferred band if available.Handover to preferred band for the purpose of radioresource handover or for reasons of congestion.Combination of TCH assignment and call handover topreferred band (ie 1 and 2 combined) when available.BSS continually monitors MS reported neighbours and handover is effected to available preferred band.Combination of TCH assignment, handover and continuous monitoring (i.e. 1,2, and 4 combined).Function is identical to 5 except that it will only betriggered when a Cell becomes congested.

0)

1)2)

3)

4)

5)

6)

FunctionParameter

TC

H A

ssig

n

Nor

mal

Han

dove

rC

ontin

uous

Mon

itorin

g


Complete Traffic Control

• Motorola has added three new parameters to controlMultiband operation:

• Multiband Reporting- 4 modes

• Band Preference- Selects which band has priority

• Band Preference Mode- 6 modes


Handover Algorithms

• GSM specifications define handover occurrence based on signal strength

• Motorola has added a further 7 algorithms (Microcellular)– to allow complete control of a multilayer network– maximising call quality and cell capacity


Seamless Interband Handover

• Intra-BSC• Intra-MSC• Inter-MSC• Priority of Band-Prefered Handover over ALL Handover

Algorithms.


Infrastructure Sharing

DCS1800BTS

GSM900/1800BTS

Shared NetworkElements

Addition of DCS 1800BTSs only

MSC

BSC

OMC-R

GSM900BTS


Homogeneous Dualband BTS

GSM900Cabinet

DCS1800Cabinet

BSC

Homogeneous BTS Cabinets

Single Logical BTS


Heterogeneous Dualband BTS

GSM900 / 1800Cabinet

BSC

Heterogeneous BTS Cabinets

Single BTS


Air Interface


Sys Info Broadcasting

• Sys info type 3 has “2ter” indicator bit in “SI 3rest octets” information element

• Set to 1 to indicate that Sys Info 2ter will be broadcast

• Various neighbour lists broadcast in various Sys Info messages, dependent upon cell type

GSM900 DCS1800BTS BTS

Sys Info 2 900 nbrs 1800 nbrsSys Info 2bis 1800 nbrsSys Info 2 ter 1800 nbrs 900 nbrs


Dedicated Mode Broadcast

• Similar BA lists exist in Sys Info 5, 5bis and 5ter

• Sys Info type and BA contents can be different for different calls and are chosen based on the BSS’sunderstanding of the MS capability

• Additionally, Sys Info 5 ter has an IE “AdditionalMultiband Information” - Multiband Reporting


Power Class

Power GSM 900 DCS 1800 Tolerance (dB)class Maximum output Maximum output for conditions

power power normal extreme1 - - - - - - 1 W (30 dBm) ± 2 ± 2.52 8 W (39 dBm) 0.25 W (24 dBm) ± 2 ± 2.53 5 W (37 dBm) ± 2 ± 2.54 2 W (33 dBm) ± 2 ± 2.55 0.8 W (29 dBm) ± 2 ± 2.5

4 W (36 dBm)


Classmark 3

• “Conventional” classmark 2 (sent in CM_SERVICE REQUEST) has bit “CM3” indicating whetherclassmark 3 will be used

• Classmark 3 contains MS power classes in DCS1800 and GSM900 bands

• MS sends classmark 3 in CLASSMARK CHANGE message in the early classmark sending procedure

• The MS sends the message as early as possible after immediate assignment

dualband

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