93912740 auspi presentation to trai on spectrum response to coai

7/30/2019 93912740 AUSPI Presentation to TRAI on Spectrum Response to COAI

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Telecom Regulatory Authority of India

Presentation on behalf of the

Association of Unified Telecom Service Providers of India

Response to Nokias Paper on Interference Issues ITU-B3 1900 Band and ITU Band 1: 1920-1980/2110-2170 MHz

Dr Y S Rao

Contribution by QUALCOMM & Lucent

13 October 2004 New Delhi


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AUSPI Proprietary 2

EXECUTIVE SUMMARY


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AUSPI Proprietary 3

Synopsis of AUSPIs stand

Present allocation in 800 MHz for CDMA Not sufficient for

multiple operators.

Internationally allocation for large operators varies from

10+10MHz to 20+20 MHz (average allocation 15+15 MHz).

CDMA operators need additional allocation in other bands togrow their networks.

Globally, CDMA systems work in 800 MHz and 1900 MHz,

with the exception of Korea

Korean PCS is unique and is not used anywhere else in theworld.

AUSPI has proposed service neutral plan of 800 MHz and

1900 MHz for CDMA and 900 MHz and 1800 MHz for GSM in

line with international standards.


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AUSPI Proprietary 4

Main points of NOKIAs presentation

GSM is opposed to 1900 MHz allocation for use by CDMAOperators

It overlaps with WARC92 recommended IMT-2000 Band of 1920-1980 MHz paired with 2110-2170 MHz

Even a small allocation of 10+10 MHz for CDMA2000

operation in the USPCS Band will cause unacceptableinterference to a WCDMA system in the WARC92 IMT-2000band

Adequate protection of the WCDMA uplink will require:

Very high rejection filters at every CDMA2000 and WCDMA Base

Station Guard bands greater than 5 MHz

Site to site coordination

15% additional IMT-2000 sites to account for lost coverage

Several thousand Euros added per site to pay for all this


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AUSPI Proprietary 5

Main points of NOKIAs presentation contd

There is no incentive for a CDMA2000 operator to invest

in filters

Experience of mixed CDMA/GSM in 800/900 MHz in

India/Asia show that CDMA operators neglect additionalfiltering

Operators do not coordinate in practice

Adequate protection of the CDMA downlink Interference

from IMT-2000/ WCDMA User Equipment (UE) andUSPCS CDMA UE is not possible

This will result in a USPCS CDMA capacity loss up to 35%


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AUSPI Proprietary 6

Our General Response

GSM opposition is unjustified: WARC-2000 has recommended different bands for IMT-

2000/3G allowing flexibility for the administration to chooseany band from:

806 960 MHz,

17101885 MHz,

25002690 MHz.

ITU-R recommendation No. M.1036.2 identified differentpaired frequency arrangements for IMT-2000

A1&A2 B1 to B6

3GPP has already standardised DCS1800 for 3G/UMTS[No. TS25.105(Rel-5)] and has already been requested toquickly standardise 900 MHz for the same


7/38AUSPI Proprietary 7

Our General Responsecontd

Notwithstanding its position to have the USPCS band

allocated for CDMA operators, AUSPI now responds to Nokia

interference issues with a mixed band plan of USPCS and

the WARC IMT-2000

As per the ERC-101 Report, there are three methods to study

interference between two adjacent frequency bands:

Minimum Coupling Loss (MCL)

Enhanced Minimum Coupling Loss (E- MCL)

Monte Carlo Method

Method used by Nokia is MCL

As per the ERC-101 Report, the MCL method evaluates the

worst case scenario and gives spectrally inefficient results



TECHNICAL RESPONSE



Clarification on band allocations near 2 GHz(ITU Definitions)

Nokia states on page 3: even the allocation of as little as 10 MHz for PCSCDMA within 1900-1910/1980-1990 MHz will severely interfere the uplink

portion (1920 - 1980 MHz) of the ITU-R globally harmonized IMT- 2000 2 GHz

band.

We believe this is confusing the technical discussion since IMT-2000(3G)

systems can be deployed in both of these bands. In ITU-R M.1036-2 the ITU

has stated that the following 3 bands (in addition to others-i.e. 1710-1770 MHz/

2110-2170 MHz) are equally valid bands for IMT-2000 and that administrations

can implement all or parts of these frequency arrangements for IMT-2000

services in the 2 GHz region. It is up to the Administrations of each country to

decide which arrangement, or mix of arrangements best suits its own needs.

ITU band 1, commonly termed the UMTS band 1920-1980/ 2110 -2170 MHz

ITU band 2, commonly termed the DCS-1800 band

1710-1785/1805-1880 MHz

ITU band 3, commonly termed the USPCS band

1850-1910/ 1930 -1990 MHz



Existing band allocations near 2 GHz(ITU Definitions)

We also note that each Standards Organization, eg

3GPP and 3GPP2, refer to these bands by other

designations

To avoid confusion in this presentation, we will refer to

these bands by their ITU designations, as shown on the

previous chart

The next chart shows these bands as defined by the

ITU.

Red lines indicate mobile transmit bands

Bluelines indicate BTS transmit bands

Green line indicates DECT assigned bands in India



0

1

2

3

4

5

1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200

1 UMTS 1920-1980/2110-2170

2 DCS-1800 1710-1785/1805-1880

3 USPCS 1850-1910/1930-1990

4 DECT 1880-1900/-

Existing ITU Band allocations near 2 GHz



0

1

2

3

4

5

1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200

1 UMTS 1920-1980/2110-2170

2 DCS-1800 1710-1785/1805-1880

3 USPCS 1900-1910/1980-1990

4 DECT 1880-1900/-

Frequency allocation arrangementaddressed by NOKIA



NOKIAs claims on a mixed band plan

Nokia claim page 3: allocation of even 10 MHz from the USPCS(ITU B3) band will essentially block the IMT-2000 evolution

The previous figure shows the allocation arrangement addressed byNokia

Our response:

Normal design practice for this arrangement will place the last WCDMA

carrier 2.5MHz below the 1980 MHz boundary and the first CDMA 2000carrier 1.25MHz above the 1980 MHz boundary. This arrangementplaces these carriers 3.75 MHz apart, and provides an inherent guardband of 1.2 MHz

1.2 MHz = 3.75(3.84+1.25)/2

Additional guard band can be obtained without essentially blocking

IMT- 2000 evolution Dropping 1 CDMA 2000 carrier gains 1.25 MHz

Dropping 1 WCDMA carrier gains 5 MHz

Reducing the WCDMA channel spacing to 4.8 MHz gains 2 MHz

These inherent and easily increased guard bands reduce therequirement on any filter designs needed to assure interference is not

an issue


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AUSPI Proprietary 15

Interference issues with mixed band planEmissions contd

Nokia claim page 4: Nokia quotes Lucent as saying 77dB of filtering at the CDMA2000 BTS may be required to solve the BTS to BTS noise interference issue.This supports an overall Isolation target of 107dB, as derived by Lucent.

Nokia also concludes that the only way to prevent interference from spuriousemissions coming from CDMA 2000 BTS transmitters in the ITU-B3 band intoWCDMA BTS receivers in the ITU-B1 band is to install additional filters in all ITU-B3 base stations.

Our comments: The requirement for 77 dB of filtering arises from Nokias assumption that

30dB of antenna isolation is all that can be obtained. But this limit onlyapplies to systems sharing the same antenna, and over 50dB of isolation canbe obtained in both collocated and non collocated arrangements that do notshare an antenna.

A more reasonable approach, stated by Lucent, is to assume a filter with

60dB rejection. Then the required antenna isolation is 47dB, well withinstandard practice.

It is not the case that expensive technical modifications of infrastructure mustoccur to permit the use of some of the PCS and ITU-B1 frequency bands. Wewill later show the only modification required is to add filters.

We further believe that 60dB filter rejection is the maximum required and willshow that it can be obtained in real, commercially available designs.


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Interference issues with mixed band planEmissions contdOur comments, contd In computing the -107 dB isolation requirement, Lucent used a worst case

Minimum Coupling Loss (MCL) analysis procedure with CDMA 2000emissions at -73dBm/Hz, plus assuming this interference arrived at theWCDMA BTS receiver 10dB below the noise floor, estimated at -170dBm/Hz. ( i.e. from a 4dB noise figure receiver). This worst case analysis

serves well to establish limits on the interference issue. Even in this worst case condition we believe that coexistence is

achievable.

However, ERC report 101 [1] states that the minimum coupling methodyields pessimistic results when compared to real world results, andrecommends a procedure if more accurate Monte-Carlo simulations are notavailable. One particular comment stands out:

The degradation should be estimated with the desired signal at 3dBabove the minimum sensitivity.

In line with these guidelines, we believe a 1dB degradation in noise figure asmore reasonable for CDMA systems, and which is actually more severe thanthat recommended by ERC-101.

This sets the allowable interference density at -176 dBm/Hz


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Interference issues with mixed band planEmissions continued

Our comments, contd

Given an allowable interference density of -176dBm/Hz at the ITU-B1 BTS receiver, and a specified emission density or 75dBm/Hzfrom the CDMA 2000 transmitter, the required isolation is 101 dB,

not 107dB If the emission density is at a more typical level, as much as 22 dB

below the specified level, the required isolation is 79 dB, far lessthan the worst case estimates

Based on these values, we would consider a reasonable isolationrequirement to be not more than 90 dB, which could be met with a50 dB filter and 40 dB of antenna coupling loss

In any case, the reduction in required isolation can be used toreduce the required antenna coupling loss, the filter rejection loss, orthe guard band


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Interference issues with mixed band planGeneral

Nokia claim on page 5: use of mitigation techniques will not work becausethere is no incentive for the perspective PCS CDMA operator in 1900-1910/1980-1990 MHz to invest and to provide the necessary additionalfiltering. Severe interference has been observed in the 800 MHz band, wherea similar boundary condition occurs.

Our response:

Nokia fails to consider that the ITU-B1 band can be shared** betweenWCDMA and CDMA 2000. CDMA 2000 may well end up on both sides of the1980 boundary. To avoid interference later, the boundary problem must beaddressed now

It is also not true that in case of CDMA 2000/GSM band plans in 800/900 MHzbands in India the operators have neglected the need for filters It is a fact that CDMA filters have been provided to solve the 850MHz

issue In addition there was a resolution between the operators to take the

necessary steps and to the best of our knowledge there are no significantinterference issues between CDMA and GSM in 800/900 MHz bands

** Notwithstanding its position to have the ITU-B3 band allocated for CDMA operators,AUSPI is responding to Nokias interference issues concerning a mixed band plan


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Interference issues with mixed band planBlocking

Nokia claim page 6: Use of mitigation techniques, if imposed upon theoperators, are not viable due to large site coordination distance, large guardbands, high cost and need for additional sites due to degradation. 114dB oftotal isolation will be required, and sites will need to be 300 Meters aparteven when 60dB of filtering is added at WCDMA receivers

Our response:

After reviewing typical data we believe 114 dB isolation is notrequired for the ITU-B3 to ITU-B1 blocking interference condition

In computing this number Lucent again used a worst case analysisprocedure

First, Lucent assumed a CDMA2000 transmitted power of 46.8dBm(for three carriers). We agree with this assumption

Lucent then computed the allowable blocking level at the WCDMAreceiver at -66.8dBm at the receiver input from the WCDMA ACSspecification

The difference of these numbers is 113.6 dB, rounded to theisolation requirement of 114dB


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Interference issues with mixed band planBlockingcontdOur response continued: Actual blocking measurements have been performed in generic programs with co-

operative partner FDD vendors and indirectly as part of co-siting tests on ITU-B1

operators FDD networks. These experiments were performed on six different FDD

vendors equipment and across all TDD channels in the core ITUB1 bands. These

measurements have been averaged to protect confidentiality and are summarised

below. Note these are considerably higher than the default specification of -55 dBm.

At 5 MHz offset the interfering signal was37dBm, 18 dB larger than the specified

level of -55dBm, and about 30 dB larger than the worst case calculated level of66.8

dBm.

Interfering channel (TDD signal) Interfering signal level for 1dB noise

rise in 1922 MHz FDD UL

1900-1905 MHz -9dBm

1905-1910 MHz -17dBm

1910-1915 MHz -27dBm

1915-1920 MHz -37dBm


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Interference issues with mixed band planBlocking contd

Our response continued: As before, after reviewing this analysis, we believe this is too severe

when using the worst case minimum coupling loss (MCL) method ofcomputing system coexistence

Given a transmitted power of 46.8dBm from three CDMA carriers,

and aspecified blocking level of -55dBm at the WCDMA receiver fora 5MHz offset, the computed isolation is 101.8dB, not 114dB

Given a transmitted power of 46.8dBm from three CDMA carriers,and a typical blocking level of -37dBm at the WCDMA receiver for a5MHz offset, the computed isolation is 83.8dB, far less than theworst case 114dB

As before, we would consider a reasonable isolation requirement tobe not more than 90 dB, which could be met with a 50 dB filter and40 dB of antenna coupling loss

In any case, the reduction in required isolation can be used toreduce the required antenna coupling loss, the filter rejection loss, orthe guard band


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Interference issues with mixed band planBlocking contd

Nokia claim page 6: Use of mitigation techniques, if imposed upon theoperators, are not viable due to large site coordination distance, large guardbands, high cost and need for additional sites due to degradation. 54 dB ofantenna isolation will be required, and sites will need to be 300 Meters aparteven when 60dB of filtering is added at WCDMA receivers. (This is to meet the114 dB total isolation requirement)

Our response continued: Site coordination distances: We do not agree with Nokias conclusion that a

300 meter minimum site-site distance is needed when 54dB of isolation isdesired. In line 6 of their table on page 6, we see Nokia has listed 54dB as theavailable antenna isolation. Since the Free Space loss at 300 Meters at 1980MHz is 88dB (as shown in the next chart) this means that Nokia has assumedBTS antenna gains of 17dB each and that they are directed exactly at eachother. Nokia also neglected any cable losses in their analysis

It is recommended ( ERC-101) that 10 dB antenna gains be used whendetermining interference. Using these values reduces the free space lossrequirement to 74dB and the site to site spacing to about 75 Meters

Analytical and measured data ( see later charts) show that 54 dB total isolationis also quite possible when antennas are mounted on the same mast


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Free Space Transmission Loss vs Distance (Assumes Isotropic Antennas)

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

0.01 0.10 1.00

Distance (Km)

Loss(dB)

1980 MHz 15.0 Meter BTS 15.0 Meter

Free Space loss model for BTS to BTSinterference calculations


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Antenna coupling for antennas mountedon a common mast

The above data may be found in prediction of Mutual Coupling between Base Station Antenna

Arrays, RAWCON 2002 conference paper.

These measurements are comparable to the following table found in contribution UK WP8F

WP(04)026, which was aimed at solving the boundary problem between TDD and FDD bands in

Europe. The data applies equally well in the case here

(a) Broadside Configuration

-70

-60

-50

-40

-30

-20-10

0

0 20 40 60 80 100 120 140 160

Separation Distance (inches)

Coupling

(dB)

Measured

Predicted

(b) Colinear Configuration

-70

-60

-50

-40

-30

-20

-10

0

0 20 40 60 80 100 120 140 160

Separation Distance (inches)

Coupling

(dB)

Measured

Predicted

Antenna configuration Coupling lossDual antennas in the same radome 30dBDefault separation on the same mast 1m 55-65dB


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Interference issues with mixed band planFilter Characteristics

Nokia claim page 7: Lucent proposal that interference problems can bemitigated by providing 2.25 MHz guard band and 60 dB additional filteringat the CDMA BS and WCDMA BS is not practical

Our response:

Considering the blocks at the band edges will most likely be 5 or10MHz wide, it is quite possible to design filters that can provide 60

dB rejection in a very small frequency range from the band edge The next chart shows the measured response of a low cost BTS

filter that can meet the objections from Nokia given a 5 MHzallocation at the edge of the band

This filter has 60 dB of rejection within 1 MHz from the band edge,

coupled with less than 0.75 dB of insertion loss. It will easily support3 CDMA2000 carriers or 1 WCDMA carrier

If the edge band allocations at 1980 MHz were 5MHz each, usingthis filter would result in the need for NO added guard band

If this filter replaced the existing filters, rather than added to theexisting filter, there would be essentially no loss in coverage


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Suitable filter for 1980 band edge isolationfor 5MHz allocations


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Interference issues with mixed band planFilter Issue (repeated)

Nokia claim page 7: Lucent proposal that interference problems canbe mitigated by providing 2.25 MHz guard band and 60 dBadditional filtering at the CDMA BS and WCDMA BS is notpractical:

Our response:

The next chart shows the simulated response of a low cost BTSfilter that can meet the objections from Nokia given a 10 MHzallocation at the edge of the band

This filter has 60 dB of rejection 2.5 MHz from the band edge,coupled with less than 0.5 dB of insertion loss in the desired band

This implies that some emissions would pass through and additionalmeans for isolation are required

Some options were discussed earlier, and using the Lucentsuggestion of having 4.8MHz spacing between WCDMA carriers isenough to solve this problem with no loss in the total number ofcarriers in either band


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Suitable filter for 1980 band edge isolationfor 10 MHz allocations


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BTS to BTS interference issues Summary

Using minimum coupling loss methods to establish Isolation requirements

leads to overly pessimistic results, not representative of the real world. Using specified performance values for transmitters and receivers to establish

Isolation requirements also leads to overly pessimistic results, since they arenot representative of the actual equipment performance.

We believe 90 dB isolation is adequate to meet the BTS to BTS interferenceconditions for both the emission and blocking issues. But that up to 114 dB

can be met with a combination of filters and antenna isolation if needed inextreme cases.

60 dB rejection filters are available

50 dB of antenna isolation is quite possible with good practice, for collocatedand non-collocated systems. Only 30 dB is possible for systems that share thesame antenna.

50 dB of antenna isolation can be achieved with site to site spacing of 30Meters.

40 dB of antenna isolation can be achieved with site to site spacing of 10Meters.

If the edge band allocations at 1980 MHz were 5MHz each, filters areavailable which would result in the need for NO added guard band.


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Interference issues: IMT-2000 handset tothe PCS CDMA handset, Monte-Carlo method

Nokia claim on page 9: mixed plan will result in interferencebetween the IMT-2000 handset to the PCS CDMA handset whenthey are in close proximity to each other

Lucent has provided TRAI with the results of a Monte-Carlo methodto estimate the issue of mobile station interference We will not repeat that presentation here, but do restate exactly the

results:

Under the assumed conditions, CDMA downlink capacitydegradation is


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Interference issues: IMT-2000 handset to thePCS CDMA handset, MCL methodcontd

In reviewing the assumptions used in the Monte-Carlo analysis, we believeadding more detailed information using an MCL method will show that the

Monte-Carlo method was pessimistic.

The typical noise floor of a CDMA2000 or WCDMA handset is about -105dBm/Hz, far less than specified. An example is shown in the following chart, for a CDMA2000 handset.

When transmitting at maximum power, this floor is reached at about +/-3.75 MHz from the center of the CDMA2000 carrier, and to not interferewith a CDMA handset, this needs to be reduced to about -170 dBm/Hz.

Allowing 3 dB of body loss, this requires 59 dB of path loss between thetwo CDMA2000 handsets, which at 1980 MHz occurs at less than 10Meter separation. This results from using a 2 slope propagation model, show in a following

chart. If the jammer is a WCDMA handset, the floor is reached at about +/-7.5

MHz.

This is a minimum coupling loss method of analysis and as before willyield pessimistic results compared to monte-carlo methods which betterreflect real world conditions, but only of real world performance is used,not justspecified performance.


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Typical CDMA2000 handset spectrum atmaximum power

Pout=24dBm

-70

-60

-50

-40

-30

-20

-10

0

10

1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885

Absolute Freq (MHz)

dBm/30kHz


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Interference issues: IMT-2000 handset to thePCS CDMA handset, MCL methodcontd

Handsets at the extreme combination of maximum power from the

jammer and minimum signal at the victim occur in very few cases

If the TX power of the handset is decreased 10 dB from maximum

the noise floor decreases significantly, reaching -100 dBm/Hz within

2.5MHz and -115 dBm/Hz within 5 MHz This is shown on the next chart

This reduces the interference distance at 5MHz offset to less than 3

meters

If the victim handset signal is 10 dB above threshold, the same

interference distance results

A combination of these reduces the interference range to less than a

meter


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Interference issues: IMT-2000 handset to

the PCS CDMA handset

If the TX power of the handset is decreased 10 dB from maximum the noisefloor decreases significantly, reaching -100 dBm/Hz within 2.5MHz and -

115dBm/Hz at 5 MHz

Handset TX Spectrum vs Output Power (20 MHz span)

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

1.9125E+09 1.9175E+09 1.9225E+09 1.9275E+09 1.9325E+09

Frequency [Hz]

Power[dBm/30kHz]

28 dBm

26 dBm

24 dBm

20 dBm

15 dBm

aa


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Path loss models for mobile to mobileinterference calculations

Transmission Loss vs Distance (Assumes Isotropic Antennas)

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

0.0 0.1 1.0

Distance (Km)

Loss(dB) 2-SLOPE MODEL

free space loss

Smooth Earth Model

1900 MHz 1.5 Meter BTS 1.5 Meter MS


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Restatement of AUSPIs position

Present allocation in 800 MHz for CDMANot sufficient for multipleoperators

Internationally allocation for large operators varies from 10+10MHz to20+20 MHz (average allocation 15+15 MHz)

CDMA operators need additional allocation in other bands to growtheir networks

Globally, CDMA systems work in 800 MHz and 1900 MHz, with theexception of Korea

Korean PCS is unique and is not used anywhere else in the world

AUSPI has proposed service neutral plan of 800 MHz and 1900 MHzfor CDMA and 900 MHz and 1800 MHz for GSM in line withinternational standards

Notwithstanding this position, we disagree with Nokias conclusionson a mixed band plan

Interference issues at the 1980 MHz boundary can be dealt withby providing filters where needed

Not all BTSs will require filters, and for those that do, these filtersare cost effective


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References

European Radio communications Committee (ERC) Report 101,

A Comparison of Minimum Coupling Loss Method, Enhanced

Minimum Coupling Loss Method and the Monte-Carlo Simulation,

Menton, 1999.

A.H. Mohammadian, L Golovanesky, S.S. Soliman, M.A.

Tassoudji, Prediction of Mutual Coupling between Base Station

Antenna Arrays, Proceedings of 2002 IEEE Radio and Wireless

Conference, Boston, MA, August 11-14, 2002.


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Thank you!

93912740 auspi presentation to trai on spectrum response to coai

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