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--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-

[[Page 253]]

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:

Prbi=10Log 
(ptbi)-Lbi-UCi+Gmwi-Ci
-BPi
Prmi=10Log 
          (nmi x ptmi)-Lmi-UCi
          +Gmwi-Ci
Prpsi=10Log 
          (npsi x ptpsi)-Lpsi-UCi
          +Gmwi-Ci
Prpbi=10Log 
          (npbi x ptpbi)-Lpbi-UCi
          -(BPi-BHi) 
          +Gmwi-Ci
Prpri=10Log 
          (npri x ptpri)-Lpri-(UCi
          -BHi)+Gmwi-Ci

where:
P refers to Power in dBm
p refers to power in milliwatts
Prbi=Power at MW receiver from ith base station in dBm
ptbi=e.i.r.p. transmitted from ith base station in 
          milliwatts, which equals average power per channel x number of 
          channels x antenna gain with respect to an isotropic antenna--
          line loss
Lbi=Path loss between MW and base station site in dB
UCi=Urban correction factor in dB
Gmwi=Gain of MW antenna in pertinent direction (dBi)
Ci=Channel discrimination of MW system in dB
Prmi=Power at MW receiver from mobiles associated with ith 
          base station
ptmi=e.i.r.p. transmitted from mobiles associated with ith 
          base station
nmi=Number of mobiles associated with ith base station
Lmi=Path loss between MW and mobile transmitters in dB
Prpsi=Power at MW receiver from outdoor portables (s for 
          sidewalk)
ptpsi=e.i.r.p. transmitted from outdoor portables associated 
          with ith base station
npsi=Number of outdoor portables associated with ith base 
          station
Lpsi=Path loss between MW and outdoor portables in dB
Prpbi=Power at MW receiver from indoor portables (b for 
          building)
ptpbi=e.i.r.p. transmitted from indoor portables associated 
          with ith base station
npbi=number of indoor portables associated with ith base 
          station
Lpbi=Path loss in dB between MW and base station site (using 
          average building height divided by 2 as effective antenna 
          height)
Prpri=Power at MW receiver from rooftop portables (r for 
          rooftop)
ptpri=e.i.r.p. transmitted from rooftop portables associated 
          with ith base station
npri=Number of rooftop portables associated with ith base 
          station
Lpri=Path loss in dB between MW and base station site (using 
          average building height as effective antenna height)
BPi=Building penetration loss at street level in dB
BHi=Height gain for portables in buildings dB=2.5 x (nf-1), 
          where nf is number of floors

    Note: where Ci 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.


[[Page 254]]

[GRAPHIC] [TIFF OMITTED] TR24JN94.017



    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 &177; 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 x (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.

[[Page 255]]

    If a co-channel PCS base station lies within the main beam of a 
microwave antenna (&177;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.