§ 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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