§ 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]

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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:

   Prbi=10Log (ptbi) -Lbi -UCi+Gmwi -Ci -BPi

   Prmi=10Log (nmi *ptmi) -Lmi -UCi+Gmwi -Ci

   Prpsi=10Log (npsi *ptpsi) -Lpsi -UCi+Gmwi -Ci

   Prpbi=10Log (npbi *ptpbi) -Lpbi -UCi -(BPi -BHi) +Gmwi -Ci

   Prpri=10Log (npri *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 * number of channels * 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 *(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.
   eCFR graphic er24jn94.017.gif

   View or download PDF

   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.

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Subpart F--Competitive Bidding Procedures for Narrowband PCS

   Source:  59 FR 26747 , May 24, 1994, unless otherwise noted.

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