WO2002060206A2

WO2002060206A2 - Mobile transmitter locator

Info

Publication number: WO2002060206A2
Application number: PCT/US2001/051240
Authority: WO
Inventors: Clifford Knight
Original assignee: Bellsouth Intellectual Property Corporation
Priority date: 2000-10-26
Filing date: 2001-10-25
Publication date: 2002-08-01
Also published as: WO2002060206A3

Abstract

A mobile transmitter locator for quickly and inexpensively evaluating potential wireless base station sites. The mobile transmitter locator includes a utility trailer. A transmitter produces test propagation signals. An antenna broadcasts the test propagation signals. The test propagation signals may comprise wireless telephone frequencies, such as frequencies within the cellular band.

Description

TITLE OF THE INVENTION Mobile Transmitter Locator

NOTICE OF COPYRIGHT PROTECTION A portion of the disclosure of this patent document and its figures contain material subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, but otherwise reserves all copyrights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to mobile communications and, more particularly, to a mobile transmitter for testing and locating wireless communication transmitters.

2. Description of the Related Art

Wireless communication has experienced explosive growth. In just a few years cellular telephone usage has soared, and more growth is planned as wireless Internet access improves. This explosive growth has revolutionized data and voice communication. ^' This explosive growth, however, presents a challenge for wireless service providers.

As cellular communication soars in use, more cellular base stations are required. These base stations house the transmitters and receivers that serve the wireless customer. Each base station covers a geographic sector, or "cell," and each cell varies in size depending upon the terrain and the number of users. As use of wireless services grows, more cells are needed and, hence, more base stations are required.

Choosing the location for a new base station, however, is extremely complicated. The location of the base station largely determines the quality and range of the cell's signal coverage. The location of the base station is important because radio waves propagate according to natural laws and not city boundaries. See NEIL J. BOUCHER, THE CELLULAR RADIO HANDBOOK 42 (1995). The tall buildings of urban areas, for example, can both confine radio waves and also cause reflections. See id. at 44. Thus the final location of a base station is often a process of evaluating many potential sites and choosing the location that offers the best compromise of many considerations. See PAUL BEDELL, CELLULAR/PCS MANAGEMENT 24-27 (1999).

Often these potential base station sites are located atop urban buildings. Engineers must somehow evaluate the quality and range of a base station signal transmitted from atop a selection of potential buildings. As most cellular designers recognize, the most reliable field strength measurements are obtained when signals are broadcast from the roof of the desired building. The field strength could be estimated using mathematical formulas, but these formulas require several correction factors. See BOUCHER, supra, at 59. An actual transmission from the potential site, called a "survey," is therefore necessary to accurately evaluate cellular reception.

Positioning an antenna at the actual desired elevation has been difficult. One conventional method of evaluating elevated antennas uses a crane or cherry-picker. A large crane or cherry-picker is brought to the potential base station site, and a boom hoists an antenna to the desired elevation. A transmission is made from the elevated antenna, and the field strength of the transmission is measured at various points within the potential cell.

When all the measurements for that potential site are complete, the crane/cherry-picker is moved to the next potential cell site.

A crane/cherry-picker, however, is an impractical method of hoisting the antenna. Cranes and cherry pickers, because of their large size, are cumbersome. This heavy equipment is extremely difficult to maneuver within tight, urban locations. Cranes and cherry-pickers also block large portions of any roadway and exacerbate traffic congestion. Bridges and low-clearance tunnels may pose delivery concerns. Utility lines may need to be removed and rerouted to accommodate the boom's large size. Cranes and cherry-pickers, in short, are so large that this conventional method is often impractical. Cranes and cherry-pickers are also very expensive to operate. Because this heavy equipment must often be rented from an independent operator, the rental charges can be hundreds of dollars per hour. Any removed and/or rerouted utility lines are an added and uimecessary expense that increase the cost of a survey. Cranes and cherry-pickers, in fact, have been said to unnecessarily double the cost of any survey. SeeBOUCHER, supra, at 87. Cranes and cherry-pickers also frequently result in unexpected expenses. Cost overruns occur despite even the best projections. The weight of heavy equipment often damages blacktop streets. Water mains and gas mains can rupture from this same weight. Buildings are damaged from an errant boom or hoisted antenna. The antenna itself has been known to unexpectedly release and fall from the boom. Falling antennas obviously endanger both workers and pedestrians.

Another method of evaluating the signal strength of a potential base station site utilizes alternative air vehicles. See BEDELL, supra, at 25; BOUCHER, supra, at 87. A blimp or balloon, for example, is tethered at the potential base station site and floated to the desired height. While balloons can be easily floated to the desired height, this method, however, is very susceptible to gusting wind. Although the blimp or balloon can be tethered by multiple ropes, the increased number of ropes alters the aerodynamics and causes the balloon/blimp to sway and dive during gusts of wind. This swaying is so prevalent that only selected antenna types can be used. Balloons and blimps, therefore, have not proven to yield reliable field strength measurements.

One final method of evaluating the signal strength of a potential base station site uses a helicopter. The helicopter lifts the antenna to the desired elevation and hovers while field strength measurements are performed. A helicopter, however, is extremely expensive and is usually only justified for remote and undeveloped mountainous locations.

All of these conventional methods are inherently inefficient. There are almost always several potential base station cell sites to be evaluated. Because cranes, cherrypickers, blimps, balloons, and even helicopters are cumbersome, only one potential location, at most, can be evaluated in a work day. One location, in fact, may require two or more work days before moving to the next location. These cumbersome conventional methods make the cell site survey very inefficient.

There is, accordingly, a need for an apparatus which can quickly be used to measure cell site field strength, which is very small and easy to maneuver between potential cdl sites, which promotes efficient field strength testing, and which is cost effective to implement.

BRIEF SUMMARY OF THE INVENTION

The aforementioned problems are minimized by a mobile transmitter locator. This mobile transmitter locator allows wireless service providers to rapidly evaluate a location for new base stations. The mobile transmitter locator is the first small, self-contained apparatus that is delivered to the potential base station site. The mobile transmitter locator transmits cellular test signals from an antenna. The antenna can be raised and lowered to any desired elevation to simulate the desired height of the base station antenna. Once the survey is completed for the site, the mobile transmitter locator is quickly and easily relocated to the next potential site. The mobile transmitter locator, therefore, provides much quicker testing than conventional methods. The mobile transmitter locator includes a transmitter. The transmitter produces test propagation signals. An antenna broadcasts the test propagation signals. The test propagation signals may include cellular telephone frequencies, such as 806-960 MHz, 1710- 1855 MHz, and 2500-2690 MHz. The antenna may optionally be telescopic, allowing the antenna to be raised or lowered to any desired height. The mobile transmitter locator is also less expensive than conventional methods.

Because the mobile transmitter locator is the first small, self-contained apparatus for evaluating potential sites, the mobile transmitter eliminates the costly and unnecessary rental expenses of conventional methods. The small size of the mobile transmitter locator also substantially eliminates the unexpected damage-related expenses of the cumbersome conventional methods.

The mobile transmitter locator also yields more efficient testing. Because the mobile transmitter locator is small and self-contained, the mobile transmitter locator is quickly and easily moved between potential cell site locations. No slow and heavy equipment needs to move through urban streets. The mobile transmitter locator allows cellular designers to conduct more tests in a work day, and the designers can quickly and easily move the mobile transmitter locator to the next potential location. The mobile transmitter locator thus promotes more efficient testing, and the total cost of a survey is reduced.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS These and other features, aspects, and advantages of the mobile transmitter locator are better understood when the following Detailed Description of the Invention is read with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic drawing showing one embodiment of the mobile transmitter locator; FIG.2 is a sectional side elevation view of the mobile transmitter locator 10 shown in

FIG. l: and FIGS. 3, 4, and 5 are schematic drawings showing alternative embodiments of the mobile transmitter locator.

DETAILED DESCRIPTION OF THE INVENTION The mobile transmitter locator of this invention allows wireless communication service providers to rapidly, inexpensively, and efficiently evaluate new base station locations. The mobile transmitter locator is the first small, self-contained apparatus that is delivered to the potential base station site. The mobile transmitter locator has an antenna that can be raised and lowered to any desired elevation up to its maximum height. The mobile transmitter locator can thus simulate the desired height of the base station antenna. Once the test survey is completed, the mobile transmitter locator is quickly and easily moved to the next potential site. The mobile transmitter locator, therefore, provides quicker testing than conventional methods.

FIG. 1 depicts a mobile transmitter locator 10 in use. The mobile transmitter locator includes a utility trailer 12. The utility trailer 12 houses equipment for transmitting communication signals (this equipment is shown and described with reference to FIG. 2). The mobile transmitter locator 10 is positioned near a desired base station site, such as a building 14. An antenna 16 is raised to simulate a transmitter atop the building 14. The equipment housed within the utility trailer 12 produces propagation test signals. The antenna 16 transmits the propagation test signals 18. The transmitted propagation test signals 18 are received by a survey vehicle 20 at a survey site. Equipment within the survey vehicle 20 receives the propagation test signals 18 and measures the propagated radio field strength within the vicinity of the survey vehicle 20.

The small size of the mobile transmitter locator 10 is greatly advantageous. The utility trailer 12 is easily maneuvered in urban environments and requires very little space when conducting propagation testing. Whereas conventional tractor-trailer rigs and cranes create congestion and disrupt traffic patterns, the smaller size of the utility trailer 12 permits propagation testing without severe traffic disruption. The mobile transmitter locator 10 is especially suitable for urban alleys where conventional tractor-trailer rigs and cranes are too large for entry and passage.

As illustrated in FIG.2, the mobile transmitter locator 10 includes the utility trailer 12. The antenna 16 is mounted to the utility trailer 12. The antenna 16 is shown including a telescopic mast 22 in a collapsed position. While a telescopic antenna is preferable for ease of mobility, a fixed-mast is usable. A transmitter 24 housed within the utility trailer 12 produces propagation test signals. The propagation test signals are transmitted along a cable 26 to the antenna 16. The antenna 16 broadcasts the propagation test signals 18. The antenna 16 may optionally include a directional or omni-directional antenna element 28 to improve radiation.

Cable 26 could be SUPERFLEX™ cable if vibration and abrasion are concerns (SUPERFLEX™ is a registered trademark of Superflex Ltd., 152 44^th Street, Brooklyn, NY 11232, 718.768.1400, www.superflex.com). Conventional coaxial cable may be used where vibration and abrasion are not a concern. RF technology could also be used to transmit signals from the transmitter 24 to the antenna 16. For instance, the industrial, scientific, and medical (ISM) band of the electromagnetic spectrum (2.4 GHZ-2.5 GHz) could be used.

The mobile transmitter locator 10 may optionally include a power source. This power source, shown as generator 30, is connected to transmitter 24 by cables 32. A battery 34 may also provide back-up power for the transmitter 24.

The mobile transmitter locator 10 includes a cargo box 36 mounted on a trailer frame 38. The cargo box 36 is preferably fabricated from aluminum; however, steel, fiberglass, and or wooden materials are suitable. The trailer frame 38 includes tongue 40. The tongue 40 conventionally accepts a ball hitch (not shown). The trailer frame 38 is supported by at least one axle 42. At least one wheel 44 is mounted to the at least one axle 42, and a tire 46 is mounted on the wheel 44. Although a single axle is shown in FIG. 2, any number of axles is contemplated to suit the weight of the mobile transmitter locator 10. An air conditioner 48 may be included to cool an interior of the cargo box 36.

The mobile transmitter locator 10 may also include a mechanism 50 for raising and lowering the antenna 16. Because the antenna 16 includes a telescopic mast 22, the mechanism 50 allows engineers to quickly and easily extend and collapse the antenna 16. The mechanism 50 is coupled to the telescopic mast. Mechanism 50 can be hydraulically- operated, electrically-operated, or manually-operated.

Those skilled in the art recognize the mobile transmitter locator 10 is applicable to all wireless communication products, methods, and frequencies. The mobile transmitter locator 10, for example, is equally applicable to wireless cellular/PCS phones, wireless computers and modems, wireless personal data assistants, global positioning devices, and any other wireless data/voice communication device. The mobile transmitter locator 10 is even applicable to satellite phones and satellite communication technology. The mobile transmitter locator 10 is applicable to code-division multiple access (CDMA) technologies, time-division multiple access (TDMA) technologies, and the global system for mobile communications (GSM) technology. The mobile transmitter locator 10 is also applicable to all frequencies in the electromagnetic spectrum and is compatible with the June, 2000 World Radiocommunication Conference agreement on third-generation cellular telephony (806-960 MHz, 1710-1885 MHz, and 2500-2690 MHz). See William Sweet, Cell phones answer Internet's call, IEEE SPECTRUM, Aug. 2000, at 43.

Alternative embodiments of the mobile transmitter locator can be included in other vehicles. FIG. 3 shows the mobile transmitter locator mounted to a utility truck 50. The utility truck shown in FIG. 3 is representative of light and medium duty trucks that are easily maneuvered in urban environments. FIG. 4 shows the mobile transmitter locator mounted to a car 52. FIG. 5 shows flie mobile transmitter locator mounted to a boat 54.

The present invention also encompasses a method of evaluating propagation field strength from a potential cellular base station site. The method includes transmitting wireless communication signals from an antenna supported by a utility trailer. The wireless communication signals comprise cellular communication signals. The method further includes positioning the antenna in substantially the same position as a proposed cell phone antenna and receiving the wireless communication signals at multiple locations within a potential cell. Once the wireless communication signals are received, the method includes evaluating propagation field strength at each location where the wireless communication signals are received. While this invention has been described with respect to various features, aspects, and embodiments, those skilled and unskilled in the art will recognize the invention is not so limited. Other variations, modifications, and alternative embodiments may be made without departing from the spirit and scope of the following claims.

Claims

CLAIMSWhat is claimed is:

1. A mobile transmitter locator, comprising:

a utility trailer; within the utility trailer a transmitter for producing test propagation signals; and an antenna for broadcasting the test propagation signals.

2. A mobile fransmitter locator according to claim 1, wherein the test propagation signals comprise cellular telephone frequencies.

3. A mobile transmitter locator according to claim 2, wherein the cellular telephone frequencies include 806-960 MHz.

4. A mobile fransmitter locator according to claim 2, wherein the cellular telephone frequencies include 1710-1855 MHz.

5. A mobile transmitter locator according to claim 2, wherein the cellular telephone frequencies include 2500-2690 MHz.

6. A mobile transmitter locator according to claim 1, wherein the antenna is supported by a telescopic mast.

7. A mobile fransmitter locator according to claim 6, further comprising a mechanism for extending and collapsing the telescopic mast.

8. A mobile fransmitter locator according to claim 1, further comprising a power source for providing electrical power to the fransmitter.

9. A mobile fransmitter locator according to claim 8, wherein the power source comprises a gasoline-powered generator.

10. A mobile fransmitter locator according to claim 8, wherein the power source comprises a solar-powered generator.

11. A mobile transmitter locator according to claim 8, wherein the power source comprises a battery.

12. A mobile fransmitter locator according to claim 1, wherein the antenna comprises a directional array.

13. A mobile fransmitter locator according to claim 1, wherein the antenna comprises an omni-directional array.

14. A method of evaluating propagation field strength from a potential cellular base station site, the method comprising:

transmitting wireless communication signals from an antenna supported by a utility trailer.

15. A method of evaluating propagation field strength according to claim 14, wherein the wireless communication signals comprise cellular communication signals.

16. A method of evaluating propagation field strength according to claim 14, the method further comprising positioning the antenna in a substantially same position as a proposed cell phone antenna.

17. A method of evaluating propagation field strength according to claim 14, the method further comprising receiving the wireless communication signals at multiple locations within a potential cell.

8. A method of evaluating propagation field sfrength according to claim 17, the method further comprising evaluating propagation field strength at each location where the wireless communication signals are received.