Method and apparatus for modeling a smart antenna in a network planning tool

• US 6,470,195 B1
• Filed: 10/31/2000
• Issued: 10/22/2002
• Est. Priority Date: 10/31/2000
• Status: Expired due to Term

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Meyer, Ronald L.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Lee, John J
• Application Number:
  US09/703,382
• Time in Patent Office: 721 Days
• Field of Search: 455/452, 455/451, 455/447, 455/25, 455/562, 455/437, 455/436, 455/442, 455/450, 455/453, 455/446, 342/373
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 16/04 Traffic adaptive resource partitioning
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A network planning tool (NPT) computer program is used to model characteristics of a wireless telephone network (10). The network contains a plurality of cells (12) which each include a plurality of sectors (16-18) disposed about a base station (13) that has a respective antenna for each sector. Techniques are provided for modeling smart antennas (131), including use of a switched-beam transmit and receive patterns with approximately random allocation among the beams of frequencies assigned to an associated sector. In the case of an adaptive beam-forming smart antenna, power levels for that antenna and a remote antenna operating at the same frequency are adjusted so as to increase a differential therebetween by an improvement value associated with the smart antenna. Potential uplink interference at a given base station is modeled by simulating operation of other base stations at an uplink frequency with a reduced power level. Potential interfering signals are discounted to the extent a smart antenna can intelligently reject a limited number of undesired signals.

Claims

1. A method comprising the step of modeling a smart antenna which has a directional operating region and which is operative with respect to a frequency group that includes a plurality of frequencies which are different, said modeling step including the steps of:

representing a transmit pattern of said smart antenna with a plurality of beams that each correspond to a respective different portion of said operating region; and

assigning said frequencies of said group approximately randomly among said plurality of beams, each said frequency of said frequency group being assigned to one of said beams.

2. A method according to claim 1, including the steps of:

providing a further antenna and a network of cells which includes first and second cells respectively associated with said smart and further antennas, said cells of said network each having at least two cell sections, and said further antenna having a directional operating region and being operative with respect to said frequencies in said frequency group, said directional operating regions of said smart and further antennas each including a selected one of the cell sections of the associated cell and excluding all other cell sections of the associated cell; and

evaluating an operational characteristic relating to at least one of said smart and further antennas.

3. A method according to claim 2, including the step of orienting said smart and further antennas so that said directional operating regions thereof extend outwardly therefrom in approximately the same direction.

4. A method according to claim 2, including the steps of:

defining an antenna list which lists a plurality of different smart antennas, and which associates with each said smart antenna in said antenna list a plurality of expected operational characteristics thereof which each correspond to a respective one of a plurality of terrain types; and

selecting said smart antenna for said first cell from said antennas in said antenna list prior to said representing and assigning steps, said selecting step including the steps of identifying for said one cell section of said first cell a corresponding one of said terrain types, and then selecting one of said antennas from said antenna group as a function of said expected operational characteristics for the identified terrain type.

5. A method according to claim 4, wherein said evaluating step includes the step of determining whether said operational characteristic satisfies a predetermined criteria;

and including the further step of responding to a determination in said evaluating step that said operational characteristic fails to meet said predetermined criteria by implementing an adjustment and then repeating said evaluating step, said adjustment including for said smart antenna at least one of adjusting an antenna transmit power, adjusting an antenna height, adjusting an antenna downward angle, adjusting an antenna orientation about a vertical axis.

6. A method according to claim 4, wherein said evaluating step includes the step of determining whether said operational characteristic satisfies a predetermined criteria;

and including the further step of responding to a determination in said evaluating step that said operational characteristic fails to meet said predetermined criteria by reassigning said frequencies of said group approximately randomly among said plurality of beams in a manner different from the random assignment during said assigning step, and by then repeating said evaluating step.

7. A method according to claim 4, wherein said evaluating step includes the step of determining whether said operational characteristic satisfies a predetermined criteria;

and including the further step of responding to a determination in said evaluating step that said operational characteristic fails to meet said predetermined criteria by selecting for said one cell section of said first cell a different one of said smart antennas in said antenna list, and by thereafter repeating said representing, assigning and evaluating steps.

8. A method according to claim 2, wherein said evaluating step includes the step of determining, for a selected said frequency from said frequency group and at each of a plurality of different evaluation points within said one cell section of one of said first and second cells, whether a predetermined value is less than a difference between power levels of respective electromagnetic signals from said smart antenna and said further antenna.

9. A method according to claim 2, wherein said evaluating step includes the step of determining, at each of a plurality of different evaluation points within a part of said one cell section of said first cell which is associated with said portion of said operating region of said smart antenna corresponding to a selected frequency of said frequency group, whether a power level of an electromagnetic signal transmitted at said selected frequency by said smart antenna is above a predetermined threshold.

10. A method according to claim 1, including the step of selecting as said smart antenna one of a switched-beam antenna and an adaptive beam forming antenna.

11. A method for modeling a wireless network which has a plurality of cells that each include at least two cell sections, and which has an antenna serving a first of said cell sections and capable of receiving signals transmitted at a selected frequency, said method comprising the steps of:

determining a first power level representing an effective power level as to said antenna for a first signal transmitted at said selected frequency by a hypothetical first mobile transmitter disposed within said first cell section;

determining a second power level representing an effective power level as to said antenna for a second signal transmitted at said selected frequency by a hypothetical second mobile transmitter disposed within a second of said cell sections different from said first cell section; and

evaluating whether a predetermined value is greater than a difference between said first and second power levels.

12. A method according to claim 11, wherein said determining and evaluating steps are carried out for each of a plurality of different evaluation points within said first cell section.

13. A method according to claim 12, wherein said step of determining said first power level includes the step of calculating for each said evaluation point the attenuated power level which a signal transmitted by the first mobile transmitter from that evaluation point would be expected to have at said antenna in view of a terrain type present in said first cell section.

14. A method according to claim 13, including the steps of:

making an empirical measurement of the actual attenuation in power level of a signal transmitted at said selected frequency from a selected one of said evaluation points to a location corresponding to said antenna; and

using said measured actual attenuation to adjust the attenuated power levels calculated for each of a plurality of said evaluation points in a group which includes said selected evaluation point.

15. A method according to claim 12, wherein said antenna is a smart antenna, and wherein said step of determining said second power level includes the step of calculating for each said evaluation point the attenuated power level which a signal transmitted at said selected frequency by the second mobile transmitter would be expected to have at that evaluation point.

16. A method according to claim 15, including the steps of:

making an empirical measurement of the actual attenuation in power level of a signal transmitted at said selected frequency from said second cell section to a location corresponding to a selected one of said evaluation points; and

using said measured actual attenuation to adjust the attenuated power levels calculated for each of a plurality of said evaluation points in a group which includes said selected evaluation point.

17. A method according to claim 15, wherein said modeled network includes a further antenna associated with said second cell section, and wherein said calculating step includes the step of using said further antenna to simulate said second mobile transmitter by:

setting modeling characteristics for said further antenna to include at least one of;

a height approximately four feet above the ground, an approximately omnidirectional transmit pattern, a transmit power corresponding to the transmit power of an actual mobile transmitter, and a transmit frequency which is said selected frequency; and

calculating at each said second power level the expected attenuated power level for a respective signal transmitted from said further antenna to a respective said evaluation point across the type of terrain present between said further antenna and that evaluation point.

18. A method according to claim 12, wherein said antenna is a smart antenna having an adaptive receive capability and having for each of a plurality of terrain types a respective predefined improvement factor, and including after said determining steps and prior to said evaluating step the further step of adjusting for each said evaluation point at least one of said first and second power levels associated therewith in a manner which increases a differential therebetween by an amount which is a function of said improvement factor corresponding to the terrain type present in said first cell section.

19. A method according to claim 18, wherein said adjustment for said improvement factor is effected by one of:

increasing said first power level by said improvement factor, decreasing said second power level by said improvement factor, and respectively increasing and decreasing said first and second power levels by respective first and second values that have a sum equal to said improvement factor.

20. A method according to claim 12, wherein said antenna is a smart antenna, and including the steps of:

defining an antenna list which lists a plurality of different smart antennas, and associating with each said smart antenna in said antenna list a plurality of expected operational characteristics thereof which each correspond to a respective one of a plurality of terrain types; and

selecting said smart antenna for said first cell section from said antennas in said antenna list prior to said determining and evaluating steps, said selecting step including the steps of identifying for said first cell section the terrain type actually present therein, and then selecting one of said antennas from said antenna group as a function of said expected operational characteristics for the identified terrain type.

21. A method according to claim 11,

wherein said antenna is a smart antenna having characteristics that permit selective rejection of signals from a specified number of transmitters;

including the step of determining a plurality of further power levels which each represent an effective power level as to said antenna for a respective further signal transmitted at said selected frequency by a respective further mobile transmitter disposed in a respective further said cell section, said further cell sections being different from each other and from each of said first and second cell sections;

including the step of carrying out each of said determining and evaluating steps for each frequency in a frequency group that includes said selected frequency; and

wherein said evaluating step includes the steps of determining the number of said transmitters for which at least one of said differences exceeds said predetermined value, identifying as operationally acceptable a situation where said specified number is not exceeded by said number of transmitters, and identifying as operationally unacceptable a situation where said specified number is exceeded by said number of transmitters.

22. A computer-readable medium encoded with a program with the capability to model a smart antenna which has a directional operating region and which is operative with respect to a frequency group that includes a plurality of frequencies which are different, wherein said program is operable when executed to:

represent a transmit pattern of said smart antenna with a plurality of beams that each correspond to a respective different portion of said operating region; and

assign said frequencies of said group approximately randomly among said plurality of beams, each said frequency of said frequency group being assigned to one of said beams.

23. A computer-readable medium according to claim 22, wherein said program is operable when executed to:

recognize a further antenna and a network of cells which includes first and second cells respectively associated with said smart and further antennas, said cells of said network each having at least two cell sections, and said further antenna having a directional operating region and being operative with respect to said frequencies in said frequency group, said directional operating regions of said smart and further antennas each including a selected one of the cell sections of the associated cell and excluding all other cell sections of the associated cell; and

evaluate an operational characteristic relating to at least one of said smart and further antennas.

24. A computer-readable medium encoded with a program capable of modeling a wireless network which has a plurality of cells that each include at least two cell sections, and which has an antenna serving a first of said cell sections and capable of receiving signals transmitted at a selected frequency, said program being operable when executed to:

determine a first power level representing an effective power level as to said antenna for a first signal transmitted at said selected frequency by a hypothetical first mobile transmitter disposed within said first cell section;

determine a second power level representing an effective power level as to said antenna for a second signal transmitted at said selected frequency by a hypothetical second mobile transmitter disposed within a second of said cell sections different from said first cell section; and

evaluate whether a predetermined value is greater than a difference between said first and second power levels.

25. A computer-readable medium according to claim 24, wherein said program is further operable when executed to carry out, for each of a plurality of different evaluation points within said first cell section, said determining of said first and second power levels and said evaluation of said difference with respect to said predetermined value.