FCC 24.253 Revised as of October 1, 2007
Goto Year:2006 |
2008
Sec. 24.253 Termination of cost-sharing obligations.
The cost-sharing plan will sunset for all PCS entities on April 4, 2005,
which is ten years after the date that voluntary negotiations commenced for
A and B block PCS entities. Those PCS entities that are paying their portion
of relocation costs on an installment basis must continue the payments until
the obligation is satisfied.
[ 61 FR 29693 , June 12, 1996]
Appendix I to Subpart E of Part 24—A Procedure for Calculating PCS Signal
Levels at Microwave Receivers (Appendix E of the Memorandum Opinion and Order)
The new Rules adopted in Part 24 stipulate that estimates of interference to
fixed microwave operations from a PCS operation will be based on the sum of
signals received at a microwave receiver from the PCS operation. This
appendix describes a procedure for computing this PCS level.
In general, the procedure involves four steps:
1. Determine the geographical coordinates of all microwave receivers
operating on co-channel and adjacent frequencies within the coordination
distance of each base station and the characteristics of each receiver,
i.e., adjacent channel susceptibility, antenna gain, pattern and height, and
line and other losses.
2. Determine an equivalent isotropically radiated power (e.i.r.p.) for each
base station and equivalent e.i.r.p. values for the mobiles and portables
associated with each base station. Determine the values of pertinent
correction and weighting factors based on building heights and density and
distribution of portables. Close-in situations, prominent hills, and extra
tall buildings require special treatment.
3. Based on PCS e.i.r.p. values, correction and weighting factors, and
microwave receiving system characteristics determined above, calculate the
total interference power at the input of each microwave receiver, using the
Longley-Rice propagation model.
4. Based on the interference power level computed in step 3, determine
interference to each microwave receiver using criteria described in Part 24
and EIA/TIA Bulletin 10–F.
The interference from each base station and the mobiles and portables
associated with it is calculated as follows:
P[rbi]=10Log (p[tbi])−L[bi]−UC[i]+G[mwi]−C[i]−BP[i]
P[rmi]=10Log (n[mi]×p[tmi])−L[mi]−UC[i]+G[mwi]−C[i]
P[rpsi]=10Log (n[psi]×p[tpsi])−L[psi]−UC[i]+G[mwi]−C[i]
P[rpbi]=10Log (n[pbi]×p[tpbi])−L[pbi]−UC[i]−(BP[i]−BH[i]) +G[mwi]−C[i]
P[rpri]=10Log (n[pri]×p[tpri])−L[pri]−(UC[i]−BH[i])+G[mwi]−C[i]
where:
P refers to Power in dBm
p refers to power in milliwatts
P[rbi]=Power at MW receiver from ith base station in dBm
p[tbi]=e.i.r.p. transmitted from ith base station in milliwatts, which
equals average power per channel × number of channels × antenna gain with
respect to an isotropic antenna − line loss
L[bi]=Path loss between MW and base station site in dB
UC[i]=Urban correction factor in dB
G[mwi]=Gain of MW antenna in pertinent direction (dBi)
C[i]=Channel discrimination of MW system in dB
P[rmi]=Power at MW receiver from mobiles associated with ith base station
p[tmi]=e.i.r.p. transmitted from mobiles associated with ith base station
n[mi]=Number of mobiles associated with ith base station
L[mi]=Path loss between MW and mobile transmitters in dB
P[rpsi]=Power at MW receiver from outdoor portables (s for sidewalk)
p[tpsi]=e.i.r.p. transmitted from outdoor portables associated with ith base
station
n[psi]=Number of outdoor portables associated with ith base station
L[psi]=Path loss between MW and outdoor portables in dB
P[rpbi]=Power at MW receiver from indoor portables (b for building)
p[tpbi]=e.i.r.p. transmitted from indoor portables associated with ith base
station
n[pbi]=number of indoor portables associated with ith base station
L[pbi]=Path loss in dB between MW and base station site (using average
building height divided by 2 as effective antenna height)
P[rpri]=Power at MW receiver from rooftop portables (r for rooftop)
p[tpri]=e.i.r.p. transmitted from rooftop portables associated with ith base
station
n[pri]=Number of rooftop portables associated with ith base station
L[pri]=Path loss in dB between MW and base station site (using average
building height as effective antenna height)
BP[i]=Building penetration loss at street level in dB
BH[i]=Height gain for portables in buildings dB=2.5×(nf–1), where nf is
number of floors
Note: where C[i]varies from channel-to-channel, which often is the case, the
summation process is more complex, requiring summation at a channel level
first.
Finally, the total PCS interference power at a given microwave receiver from
all the base stations in a given frequency band is found by summing the
contributions from the individual stations. Likewise, the total interference
power at a given microwave receiver from all mobiles and portables operating
in a given frequency band is found by summing the contributions from the
mobiles and portables associated with each cell.
[MATH: :MATH]
Base Stations. Interference from each base station to each microwave should
normally be considered independently. A group of base stations having more
or less (within 50 percent) the same height above average terrain, the same
e.i.r.p., basically the same path to a microwave receiving site, and
subtending an angle to that receiving site of less than 5 degrees, may be
treated as a group, using the total power of the group and the average
antenna height of the group to calculate path loss, L.
Mobile Stations. The e.i.r.p. from mobile transmitters is weighted according
to the number of base station channels expected to be devoted to mobile
operation at any given time. The antenna height of mobiles used in
calculating path loss, L, is assumed to be 2 meters.
Portable Stations. The e.i.r.p. from the portable units associated with each
base station is weighted according to the estimated portion of portables
associated with that cell expected to be operated inside buildings at any
given time and the portion which could be expected to be operating from
elevated locations, such as balconies or building rooftops. For example, in
the case of service intended for business use in an urban area, one might
expect that perhaps 85 percent of the portables in use at any given time
would be operating from within buildings and perhaps 5 percent might be
operating from rooftops or balconies. The remaining 10 percent would be
outside at street level.
Calculation of an equivalent e.i.r.p. for cells in suburban areas will
involve different weighting criteria.
Urban Correction Factor. The urban correction factor (UC) depends on the
height and density of buildings surrounding a base station. For the core
area of large cities, it is assumed to be 35 dB. For medium size cities and
fringe areas of large cities (4- to 6-story buildings with scattered taller
buildings and lower buildings and open spaces) it is assumed to be 25 dB;
for small cities and towns, 15 dB, and for suburban residential areas (one-
and two-story, single family houses with scattered multiple-story apartment
buildings, shopping centers and open areas), 10 dB.
The unadjusted urban correction factor, UC, should not be applied to base
station antenna heights that are greater than 50 percent of the average
building height for a cell.
Building Height and Building Penetration Factors. The building height
correction, BH, is a function of the average building height within the
nominal coverage area of the base station. It is used in conjunction with
the building penetration loss, BP, to adjust the expected interference
contribution from that portion of the portables transmitting from within
buildings. The adjustment is given by:
BP=20 dB in urban areas
BP=10 dB in suburban areas
BH=2.5×(nf–1) dB
where nf is the average height (number of floors) of the buildings in the
area.
(Note that this formula implies a net gain when the average building height
is greater than 8 floors). All buildings more than twice the average height
should be considered individually. The contribution to BH from that portion
of portables in the building above the average building height should be
increased by a factor of 20Log(h) dB, where h is the height of the portables
above the average building height in meters.
Channel Discrimination Factor. A factor based on the interference
selectivity of the microwave receiver.
Propagation Model. The PCS to microwave path loss, L, is calculated using
the Longley-Rice propagation model, Version 1.2.2., in the point-to-point
mode. The Longley-Rice [1] model was derived from NBS Technical Note 101
[2], and updated in 1982 by Hufford [3]. Version 1.2.2 incorporated
modifications described in a letter by Hufford [4] in 1985. Terrain
elevations used as input to the model should be from the U.S. Geological
Survey 3-second digitized terrain database.
Special Situations. If a cell size is large compared to the distance between
the cell and a microwave receiving site so that it subtends an angle greater
than 5 degrees, the cell should be subdivided and calculations should be
based on the expected distribution of mobiles and portables within each
subdivision.
If terrain elevations within a cell differ by more than a factor of
two-to-one, the cell should be subdivided and microwave interference
calculations should be based on the average terrain elevation for each
subdivision.
If a co-channel PCS base station lies within the main beam of a microwave
antenna ( 5 degrees), there is no intervening terrain obstructions, and the
power at the microwave receiver from that base station, assuming free space
propagation, would be 3 dB or less below the interference threshold,
interference will be assumed to exist unless the PCS licensee can
demonstrate otherwise by specific path loss calculations based on terrain
and building losses.
If any part of a cell or cell subdivision lies within the main beam of a
co-channel microwave antenna, there is no intervening terrain obstructions,
and the accumulative power of 5 percent or less of the mobiles, assuming
free space propagation would be 3 dB or less below the interference
threshold, interference will be assumed to exist unless the PCS licensee can
demonstrate otherwise by specific path loss calculations based on terrain
and building losses.
If a building within a cell or cell subdivision lies within the main beam of
a co-channel microwave antenna, there is no intervening terrain
obstructions, and the cumulative power of 5 percent or fewer of the
portables, assuming free space propagation, would be 3 dB or less below the
interference threshold, interference will be assumed to exist unless the PCS
licensee can demonstrate otherwise by specific path loss calculations based
on terrain and building losses.
References:
1. Longley, A.G. and Rice, P.L., “Prediction of Tropospheric Radio
Transmission Loss Over Irregular Terrain, A Computer Method-1968”, ESSA
Technical Report ERL 79–ITS 67, Institute for Telecommunications Sciences,
July 1968.
2. Rice, P.L. Longley, A.G., Norton, K.A., Barsis, A.P., “Transmission Loss
Predictions for Tropospheric Communications Circuits,” NBS Technical Note
101 (Revised), Volumes I and II, U.S. Department of Commerce, 1967.
3. Hufford, G.A., Longley, A.G. and Kissick, W.A., “A Guide to the use of
the ITS Irregular Terrain Model in the Area Prediction Mode”, NTIA Report
82–100, U.S. Department of Commerce, April 1982. Also, Circular letter,
dated January 30, 1985, from G.A. Hufford, identifying modifications to the
computer program.
4. Hufford, G.A., Memorandum to Users of the ITS Irregular Terrain Model,
Institute for Telecommunications Sciences, U.S. Department of Commerce,
January 30, 1985.
Subpart F—Competitive Bidding Procedures for Narrowband PCS
Source: 59 FR 26747 , May 24, 1994, unless otherwise noted.
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:MATH] Base Stations. Interference from each base station to each microwave should normally be considered independently. A group of base stations having more or less (within 50 percent) the same height above average terrain, the same e.i.r.p., basically the same path to a microwave receiving site, and subtending an angle to that receiving site of less than 5 degrees, may be treated as a group, using the total power of the group and the average antenna height of the group to calculate path loss, L. Mobile Stations. The e.i.r.p. from mobile transmitters is weighted according to the number of base station channels expected to be devoted to mobile operation at any given time. The antenna height of mobiles used in calculating path loss, L, is assumed to be 2 meters. Portable Stations. The e.i.r.p. from the portable units associated with each base station is weighted according to the estimated portion of portables associated with that cell expected to be operated inside buildings at any given time and the portion which could be expected to be operating from elevated locations, such as balconies or building rooftops. For example, in the case of service intended for business use in an urban area, one might expect that perhaps 85 percent of the portables in use at any given time would be operating from within buildings and perhaps 5 percent might be operating from rooftops or balconies. The remaining 10 percent would be outside at street level. Calculation of an equivalent e.i.r.p. for cells in suburban areas will involve different weighting criteria. Urban Correction Factor. The urban correction factor (UC) depends on the height and density of buildings surrounding a base station. For the core area of large cities, it is assumed to be 35 dB. For medium size cities and fringe areas of large cities (4- to 6-story buildings with scattered taller buildings and lower buildings and open spaces) it is assumed to be 25 dB; for small cities and towns, 15 dB, and for suburban residential areas (one- and two-story, single family houses with scattered multiple-story apartment buildings, shopping centers and open areas), 10 dB. The unadjusted urban correction factor, UC, should not be applied to base station antenna heights that are greater than 50 percent of the average building height for a cell. Building Height and Building Penetration Factors. The building height correction, BH, is a function of the average building height within the nominal coverage area of the base station. It is used in conjunction with the building penetration loss, BP, to adjust the expected interference contribution from that portion of the portables transmitting from within buildings. The adjustment is given by: BP=20 dB in urban areas BP=10 dB in suburban areas BH=2.5×(nf–1) dB where nf is the average height (number of floors) of the buildings in the area. (Note that this formula implies a net gain when the average building height is greater than 8 floors). All buildings more than twice the average height should be considered individually. The contribution to BH from that portion of portables in the building above the average building height should be increased by a factor of 20Log(h) dB, where h is the height of the portables above the average building height in meters. Channel Discrimination Factor. A factor based on the interference selectivity of the microwave receiver. Propagation Model. The PCS to microwave path loss, L, is calculated using the Longley-Rice propagation model, Version 1.2.2., in the point-to-point mode. The Longley-Rice [1] model was derived from NBS Technical Note 101 [2], and updated in 1982 by Hufford [3]. Version 1.2.2 incorporated modifications described in a letter by Hufford [4] in 1985. Terrain elevations used as input to the model should be from the U.S. Geological Survey 3-second digitized terrain database. Special Situations. If a cell size is large compared to the distance between the cell and a microwave receiving site so that it subtends an angle greater than 5 degrees, the cell should be subdivided and calculations should be based on the expected distribution of mobiles and portables within each subdivision. If terrain elevations within a cell differ by more than a factor of two-to-one, the cell should be subdivided and microwave interference calculations should be based on the average terrain elevation for each subdivision. If a co-channel PCS base station lies within the main beam of a microwave antenna ( 5 degrees), there is no intervening terrain obstructions, and the power at the microwave receiver from that base station, assuming free space propagation, would be 3 dB or less below the interference threshold, interference will be assumed to exist unless the PCS licensee can demonstrate otherwise by specific path loss calculations based on terrain and building losses. If any part of a cell or cell subdivision lies within the main beam of a co-channel microwave antenna, there is no intervening terrain obstructions, and the accumulative power of 5 percent or less of the mobiles, assuming free space propagation would be 3 dB or less below the interference threshold, interference will be assumed to exist unless the PCS licensee can demonstrate otherwise by specific path loss calculations based on terrain and building losses. If a building within a cell or cell subdivision lies within the main beam of a co-channel microwave antenna, there is no intervening terrain obstructions, and the cumulative power of 5 percent or fewer of the portables, assuming free space propagation, would be 3 dB or less below the interference threshold, interference will be assumed to exist unless the PCS licensee can demonstrate otherwise by specific path loss calculations based on terrain and building losses. References: 1. Longley, A.G. and Rice, P.L., “Prediction of Tropospheric Radio Transmission Loss Over Irregular Terrain, A Computer Method-1968”, ESSA Technical Report ERL 79–ITS 67, Institute for Telecommunications Sciences, July 1968. 2. Rice, P.L. Longley, A.G., Norton, K.A., Barsis, A.P., “Transmission Loss Predictions for Tropospheric Communications Circuits,” NBS Technical Note 101 (Revised), Volumes I and II, U.S. Department of Commerce, 1967. 3. Hufford, G.A., Longley, A.G. and Kissick, W.A., “A Guide to the use of the ITS Irregular Terrain Model in the Area Prediction Mode”, NTIA Report 82–100, U.S. Department of Commerce, April 1982. Also, Circular letter, dated January 30, 1985, from G.A. Hufford, identifying modifications to the computer program. 4. Hufford, G.A., Memorandum to Users of the ITS Irregular Terrain Model, Institute for Telecommunications Sciences, U.S. Department of Commerce, January 30, 1985. Subpart F—Competitive Bidding Procedures for Narrowband PCS Source: 59 FR 26747 , May 24, 1994, unless otherwise noted.