1. Field of the Invention
The present invention generally relates to engineering and management systems for the design of wireless systems and, more particularly, to a method for displaying the performance of wireless systems in any environment (e.g., buildings, floors within a building, campuses, within cities, an outdoor setting, etc.) using a three-dimensional (3-D) visualization method.
2. Description of the Prior Art
As wireless communication systems proliferate, radio frequency (RF) coverage within and around buildings, and radio signal penetration into and out of buildings, has become a critical design issue for wireless engineers who must design and deploy cellular telephone systems, paging systems, or new wireless technologies such as personal communication systems (PCS), wireless local area networks (WLAN), and local multi-point distribution systems (LMDS). In addition, RP networks involving micromachinery, RF identification tags, and optical communication links are of increasing interest. Designers are frequently requested to determine if a radio transceiver location or base station cell site can provide adequate, reliable service throughout a room, a building, an entire city, a campus, a shopping mall, or any other environment. The costs of in-building and microcellular wireless communication devices are diminishing while the workload for wireless system design engineers and technicians to deploy such systems is increasing sharply. Given these factors, rapid engineering design and deployment methods accompanied by comprehensive system performance visualization and analysis methods are vital to wireless communication system designers.
Common to all wireless communication system designs is the desire to maximize the performance and reliability of the system while minimizing the deployment costs. Analyzing radio signal coverage and interference is of critical importance for a number of reasons. A design engineer must determine if an existing wireless system will provide sufficient signal power throughout the desired service area. Alternatively, wireless engineers must determine whether local area coverage will be adequately supplemented by existing large scale outdoor wireless systems, or macrocells, or whether indoor wireless transceivers, or picocells, must be added. The placement of these cells is critical from both a cost and performance standpoint. The design engineer must predict how much interference can be expected from other wireless systems and where it will manifest itself within the environment.
Depending upon the design goals, the performance of a wireless communication system may involve a combination of one or more factors. For example, the total area covered in adequate received signal strength (RSSI), the area covered in adequate data throughput levels, and the number of customers that can be serviced by the system are among the deciding factors used by design engineers in planning the placement of communication equipment comprising the wireless system. Thus, maximizing the performance of a wireless system may involve the complex analysis of multiple, potentially unrelated factors. The ability to display the results of such analysis in a manner easily interpretable by design engineers is invaluable in wireless system deployment. Three dimensional (3-D) visualization of wireless system operating parameters provides the user with rapid assimilation of large data sets and their relation to the physical environment. As wireless systems proliferate, these issues must be resolved quickly, easily, and inexpensively, in a systematic and repeatable manner.
There are many computer aided design (CAD) products on the market that can be used to design a computerized model of an environment. WiSE(trademark) from Lucent Technology, Inc., SignalPro(trademark) from EDX, PLAnet(trademark) by Mobile Systems International, Inc., and TEMS from Ericsson are examples of CAD products developed to aid in the design of wireless communication systems.
Lucent Technology, Inc., offers WiSE(trademark) as a design tool for wireless communication systems. The WiSE system predicts the performance of wireless communication systems based on a computer model of a given environment using a deterministic radio coverage predictive technique known as ray tracing.
EDX offers SignalPro(trademark) as a design tool for wireless communication systems. The SignalPro system predicts the performance of wireless communication systems based on a computer model of a given environment using a deterministic RF power predictive technique known as ray tracing.
Mobile Systems International, Inc., offers PLAnet(trademark) as a design tool for wireless communication systems. The PLAnet system predicts the performance of macrocellular wireless communication systems based upon a computer model of a given environment using statistical and empirical predictive techniques.
Ericsson Radio Quality Information Systems offers TEMS(trademark) as a design and verification tool for wireless communication indoor coverage. The TEMS system predicts the performance of indoor wireless communication systems based on a building map with input base transceiver locations and using empirical radio coverage models.
The above-mentioned design tools have aided wireless system designers by providing facilities for predicting the performance of wireless communication systems and displaying the results in the form of flat, two-dimensional grids of color or flat, two-dimensional contour regions. Such displays, although useful, are limited by their two-dimensional nature in conveying all nuances of the wireless system performance. For example, slight variations in color present in a two-dimensional grid of color, which may represent changes in wireless system performance that need to be accounted for, may be easily overlooked. Furthermore, as wireless systems proliferate, the ability to visually predict and design for coverage and interference is of increasing value.
In addition, recent research efforts by ATandT Laboratories, Brooklyn Polytechnic, and Virginia Tech are described in papers and technical reports entitled:
S. Kim, B. J. Guarino, Jr., T. M. Willis III, V. Erceg, S. J. Fortune, R. A. Valenzuela, L. W. Thomas, J. Ling, and J. D. Moore, xe2x80x9cRadio Propagation Measurements and Predictions Using Three-dimensional Ray Tracing in Urban Environments at 908 MHZ and 1.9 GHz, xe2x80x9d IEEE Transactions on Vehicular Technology, vol. 48, no. 3, May 1999 (hereinafter xe2x80x9cRadio Propagationxe2x80x9d);
L. Piazzi, H. L. Bertoni, xe2x80x9cAchievable Accuracy of Site-Specific Path-Loss Predictions in Residential Environments,xe2x80x9d IEEE Transactions on Vehicular Technology, vol. 48, no. 3, May 1999 (hereinafter xe2x80x9cSite-Specificxe2x80x9d);
G. Durgin, T. S. Rappaport, H. Xu, xe2x80x9cMeasurements and Models for Radio Path Loss and Penetration Loss In and Around Homes and Trees at 5.85 GHz,xe2x80x9d IEEE Transactions on Communications, vol. 46, no. 11, November 1998;
T. S. Rappaport, M. P. Koushik, J. C. Liberti, C. Pendyala, and T. P. Subramanian, xe2x80x9cRadio Propagation Prediction Techniques and Computer-Aided Channel Modeling for Embedded Wireless Microsystems,xe2x80x9d ARPA Annual Report, MPRG Technical Report MPRG-TR-94-12, Virginia Tech, July 1994;
T. S. Rappaport, M. P. Koushik, C. Carter, and M. Ahmed, xe2x80x9cRadio Propagation Prediction Techniques and Computer-Aided Channel Modeling for Embedded Wireless Microsystems,xe2x80x9d MPRG Technical Report MPRG-TR-95-08, Virginia Tech, July 1994;
T. S. Rappaport, M. P. Koushik, M. Ahmed, C. Carter, B. Newhall, and N. Zhang, xe2x80x9cUse of Topographic Maps with Building Information to Determine Antenna Placements and GPS Satellite Coverage for Radio Detection and Tracking in Urban Environments,xe2x80x9d MPRG Technical Report MPRG-TR-95-14, Virginia Tech, September 1995;
T. S. Rappaport, M. P. Koushik, M. Ahmed, C. Carter, B. Newhall, R. Skidmore, and N. Zhang, xe2x80x9cUse of Topographic Maps with Building Information to Determine Antenna Placement for Radio Detection and Tracking in Urban Environments,xe2x80x9d MPRG Technical Report MPRG-TR-95-19, Virginia Tech, November 1995; and
S. Sandhu, M. P. Koushik, and T. S. Rappaport, xe2x80x9cPredicted Path Loss for Rosslyn, Va., Second set of predictions for ORD Project on Site Specific Propagation Prediction,xe2x80x9d MPRG Technical Report MPRG-TR-95-03, Virginia Tech, March 1995.
The papers and technical reports are illustrative of the state-of-the-art in site-specific radio wave propagation modeling. While most of the above papers describe a comparison of measured versus predicted RF signal coverage and present tabular or two dimensional (2-D) methods for representing and displaying predicted data, they do not report a comprehensive method for visualizing and analyzing wireless system performance. The xe2x80x9cRadio Propagationxe2x80x9d and xe2x80x9cSite-Specificxe2x80x9d papers make reference to 3-D modeling, but do not offer display methods or graphical techniques to enable a user to visualize signal coverage or interference in 3-D.
It is therefore an object of the present invention to facilitate the three-dimensional, multi-colored display of predicted performance results for any type of wireless communication system.
It is another object of the present invention to provide a mechanism for viewing a three-dimensional display of predicted performance results from any angle, orientation, distance, or perspective.
It is another object of the present invention to provide a mechanism for viewing a three-dimensional display of predicted performance results and interacting with the display in real-time to alter the current viewpoint and perspective.
It is another object of the present invention to provide said display of predicted performance results overlaid on a three-dimensional database that may involve a plurality of building structures and the surrounding terrain, flora, climatic conditions, and additional static and dynamic obstacles (e.g., automobiles, people, filing cabinets, etc.).
It is another object of the present invention to provide a mechanism for coloring, shading, and otherwise rendering a solid representation of said three-dimensional display utilizing multiple colors and transparency effects.
According to the present invention, a system is provided for allowing a RF system designer to dynamically model a wireless system electronically in any environment. The method includes the selection and placement of models of various wireless system hardware components, such as antennas (point, omnidirectional, directional, leaky feeder, etc.), transceivers, amplifiers, cables, splitters, and the like, and allows the user to visualize, in three-dimensions, the effects of their placement and movement on overall system performance throughout the modeled environment. Thus, the placement of components can be refined and fine-tuned prior to actual implementation of a system to ensure that all required regions of the desired service area are blanketed with adequate RF coverage, data throughput, or system performance. The three-dimensional visualization of system performance provides RF system designers with tremendous insight into the functioning of the modeled wireless communication system, and represents a marked improvement over previous visualization techniques.
To accomplish the above, a 3-D model of the physical environment is stored as a CAD model in an electronic database. The physical, electrical, and aesthetic parameters attributed to the various parts of the environment such as walls, floors, foliage, buildings, hills, and other obstacles that affect radio waves are also stored in the database. A representation of the 3-D environment is displayed on a computer screen for the designer to view. The designer may view the entire environment in simulated 3-D, zoom in on a particular area of interest, or dynamically alter the viewing location and perspective to create a xe2x80x9cfly-throughxe2x80x9d effect. Using a mouse or other input positioning device the designer may select and view various communication hardware device models from a series of pull-down menus. A variety of amplifiers, cables, connectors, and other hardware devices may be selected, positioned, and interconnected in a similar fashion by the designer to form representations of complete wireless communication systems.
A region of any shape or size may be selected anywhere within the displayed environment, or automatically selected based upon certain criteria (e.g., selecting an entire building). The selected region is overlaid with a grid containing vertices of selectable size, shape, and spacing to form a mesh or blanket. Each vertex corresponds to a single point within the 3-D environment. Thereafter, a wireless system performance prediction model is run whereby the computer displays on the screen at each vertex of the mesh the predicted RF values, for instance, received signal strength intensity (RSSI), network throughput, bit error rate, frame error rate, signal-to-interference ratio (SIR), and signal-to-noise ratio (SNR), provided by the communication system just designed. The display is such that the computer adjusts the elevation and/or coloring including characteristics such as saturation, hue, brightness, line type and width, transparency, surface texture, etc., of each vertex relative to the surrounding vertices to correspond to the calculated RF values. The coloring and elevation may correspond to the same calculated RF value or to different calculated RF values. For example, elevation may correspond to received signal strength intensity (RSSI), and color may correspond to signal-to-noise ratio (SNR), or any other of a variety of calculated RF parameters. The user is able to specify boundaries for this display in terms of selecting the range of elevations, colors, or other aesthetic characteristics from which the vertices of the mesh are assigned. Alternatively, the system can automatically select limits and ranges for the heights, colors, and other aesthetic characteristics. The result is a region of fluctuating color and elevation representing the changing wireless system performance throughout different portions of the modeled 3-D environment. The region may be viewed overlaid with the 3-D environment.