Method and apparatus for selecting a cost effective call blocking probability distribution in the design of a new cellular network

• US 5,826,218 A
• Filed: 05/29/1997
• Issued: 10/20/1998
• Est. Priority Date: 05/29/1997
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Khafizov, Farid, Jain, Nikhil
• Primary Examiner(s): Barlow, Jr., John E.
• Assistant Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US08/864,500
• Time in Patent Office: 509 Days
• Field of Search: 364/554, 455/403, 455/405, 455/422, 455/436, 455/445, 455/450, 455/451, 455/452, 455/453, 370/229, 370/235, 370/254, 370/310, 370/328, 375/200, 702/179
• US Class Current: 702/179
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 16/22 Traffic simulation tools or models

Abstract

A method for optimizing the distribution of call blocking probabilities in the design of a new cellular system to minimize the total cost of the system. In most systems, the cost of cells including real estate, RF channels antenna construction, etc. comprises the most costly portion of the system. As allowable call blocking for a cell increases, the area coverage of the cells increases and thus the total number of cells required decreases for servicing a given area. Thus, the system should be designed having the maximum number of vocoders in the BSC and the maximum number of channel elements in each base station for initial system design with the number of channel elements being optimized after the number of cells and placement thereof is finalized. The algorithm of the present invention, accomplishes the optimization by completing the design in the manner of the last sentence.

Claims

1. The method of designing a new cellular system having a given total blocking probability BP for the system comprising, the steps of:

a. assigning a minimum possible vocoder blocking probability value to B_-- VC;

b. assigning an initial minimum possible channel element blocking probability value to B_-- BTS;

c. assigning a RF blocking probability value to B_-- RF of (BP-z)/(1-z) where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. designing a network configuration wherein RF blocking approaches B_-- RF for at least one cell but does not exceed B_-- RF in any of a plurality of N cells;

e. computing actual RF blocking for a first of said N cells and assigning same to B_-- RF_i where i=first cell;

f. computing the minimum number of channel elements for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. computing actual RF blocking B_-- RF_i and number of channel elements B_-- BTS_i in the manner set forth in paragraphs e and f for each of the remaining N-1 cells.

2. A method of designing a new cellular system having a given total blocking probability BP for both RF and wired network portions of the system, a total traffic in the system of T_t, an average expected traffic in each cell of A_t, a main switch having a maximum possible number of vocoders N_-- VC, and a maximum possible number of channel elements N_-- CC in a base station comprising, the steps of:

a. calculating a minimum vocoder blocking probability value B_-- VC as a function of T_t and N_-- VC;

b. calculating a minimum channel element blocking probability value B_-- BTS as a function of A_t and N_-- CC;

c. calculating a maximum RF blocking probability B_-- RF where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. designing a network configuration wherein RF blocking does not exceed B_-- RF in any of a designed N cells;

e. computing actual RF blocking for a first of said N cells and assigning same to B_-- RF_i where i=first cell;

f. computing the minimum number of channel elements for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. completing steps e and f for each of the remaining N-1 cells.

3. A computer programmed for designing a new cellular system having a given total blocking probability BP for both RF and wired network portions of the system, a total traffic in the system of T_t, an average expected traffic in each cell of A_t, a main switch having a maximum possible number of vocoders N_-- VC, and a maximum possible number of channel elements N_-- CC in each of a plurality of base stations comprising, in combination:

a. means for calculating a minimum vocoder blocking probability value B_-- VC as a function of T_t and N_-- VC;

b. means for calculating a minimum channel element blocking probability value B_-- BTS as a function of A_t and N_-- CC;

c. means for calculating a maximum RF blocking probability B_-- RF where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. means for configuring a network of N cells and a total traffic of T_t wherein RF blocking does not exceed B_-- RF in any of the N cells;

e. means for computing actual RF blocking for a first of said N cells and assigning same to B_-- RF_i where i=first cell;

f. means for computing the minimum number of channel elements required for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. means for completing steps e. and f. for each of the remaining N-1 cells.

4. A method of designing a cellular radio system where BP represents the total call blocking probability of the system comprising, the steps of:

a. calculating a minimum vocoder blocking probability value B_-- VC as a function of total system traffic and maximum possible number of vocoders;

b. calculating a minimum channel element blocking probability value B_-- BTS as a function of average traffic per cell and the maximum possible number of channel elements in a base station of the cell;

c. calculating a maximum RF blocking probability B_-- RF where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. designing a network configuration wherein RF blocking does not exceed B_-- RF in any of the system cells;

e. computing actual RF blocking for a first one of said system cells and assigning same to B_-- RF_i where i=first cell;

f. computing the minimum number of channel elements for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. completing stops e. and f. for each of the remaining system cells.

5. A method of designing a cellular system network configuration for a system having a maximum call blocking probability of BP comprising, the steps of:

a. calculating a maximum RF blocking probability B_-- RF for each of N cells where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities, and where B_-- VC is indicative of minimum vocoder blocking probability using a maximum possible number of vocoders in a main switch and further where B_-- BTS is indicative of minimum channel element blocking probability using a maximum possible number of channel elements in a base station of each cell;

b. computing actual RF blocking for a first one of said N cells and assigning same to B_-- RF_i where i=first cell;

c. computing the minimum number of channel elements for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

d. completing steps b and c for each of the remaining N-1 system cells.

6. A method of designing a cellular system network for a system having a given maximum call blocking probability of BP wherein there are at least three variables X, Y and Z contributing to call blocking probability of BP where a minimum possible call blocking probability of X contributes the least to total system cost and where a minimum possible call blocking probability of Z contributes the most to total system cost comprising, the steps of:

a. calculating a minimum possible call blocking probability value BX for variable X;

b. calculating a minimum possible call blocking probability value BY for variable Y;

c. calculating a maximum possible call blocking probability BZ where BZ=(BP-z)/(1-z) where z=BX+BY-(BX*BY);

d. designing a network configuration wherein the call blocking in the system for variable Z does not exceed BZ in any part of the system;

e. computing actual call blocking due to variable Z for a first part of said system and assigning same to BZ_i where i=first system part;

f. computing the minimum number of variable Y for system part "i" based on a maximum allowable call blocking probability of BY_i =(BP-z)/(1-z) where z=BX+BZ_i -(BX*BZ_i); and

g. completing steps e. and f. for each of the remaining system parts.

7. A method of designing a cellular radio system having a maximum call blocking probability of BP comprising, the steps of:

a. calculating a minimum possible vocoder blocking probability value B_-- VC;

b. calculating an initially used minimum channel element blocking probability value B_-- BTS;

c. calculating a maximum RF blocking probability B_-- RF where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. designing a network configuration wherein RF blocking does not exceed B_-- RF in any of the system cells;

e. computing actual RF blocking for a first one of said system cells and assigning same to B_-- RF_i where i equals cell being considered;

f. computing the minimum possible number of channel elements for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. completing steps e. and f. for each of the remaining system cells.

8. A computer programmed for designing a new cellular system having a maximum call blocking probability of BP comprising, in combination:

a. means for calculating a minimum possible vocoder blocking probability value B_-- VC;

b. means for calculating an initial minimum possible channel element blocking probability value B_-- BTS;

c. means for calculating a maximum RF blocking probability B_-- RF where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. means for configuring a network of cells wherein RF blocking does not exceed B_-- RF in any of the resultant configured plurality of N cells;

e. means for computing actual RF blocking for a first of said N cells and assigning same to B_-- RF_i where i=first cell;

f. means for computing the minimum number of channel elements required for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. means for completing steps e. and f. for each of the remaining N-1 cells.

9. A cellular system having a total call blocking probability of BP and including a plurality of base stations wherein each base station has a call blocking probability of BCmin when equipped with a maximum possible number of channel elements comprising, in combination:

a switch including the maximum possible number of vocoders and having a call blocking probability of BV; and

a plurality of base stations, said base stations linked to said switch, each said base station including channel elements, the number of channel elements in each base station being substantially equal to but not exceeding (BP-z)/(1-z) where z equals the sum of BRF (the radio frequency minimum call blocking probability) and BV less the product of BV and BRF where the system was designed to provide a BRF of (BP-z)/( 1-z) where z=BCmin+BV-(BCmin*BV).

10. A method of designing a cellular radio system having a maximum call blocking probability of BP comprising, the steps of:

a. determining a minimum possible vocoder blocking probability value BVC;

b. determining an initially used minimum channel element blocking probability value B_-- BTS;

c. determining a radio frequency blocking probability B_-- RF where B_-- RF=(BP-z)/(1-z) and where "z" equals the sum of the vocoder and channel element blocking probabilities less the product of the vocoder and channel element blocking probabilities;

d. designing a network configuration wherein radio frequency blocking does not exceed B_-- RF in any of the system cells;

e. determining actual radio frequency blocking for a first one of said system cells and assigning same to B_-- RF_i where i equals cell being considered;

f. determining the minimum possible number of channel elements for cell "i" based on a maximum allowable channel element blocking probability of B_-- BTS_i =(BP-z)/(1-z) where "z" equals the sum of the radio frequency and vocoder blocking probabilities less the product of the radio frequency and vocoder blocking probabilities; and

g. completing steps e. and f. for each of the remaining system cells.