Data processing: structural design – modeling – simulation – and em – Modeling by mathematical expression
Reexamination Certificate
1999-01-22
2002-09-03
Frejd, Russell (Department: 2123)
Data processing: structural design, modeling, simulation, and em
Modeling by mathematical expression
C703S001000, C455S003010, C340S854600
Reexamination Certificate
active
06446031
ABSTRACT:
TECHNICAL FIELD
The present invention relates to efficient calculation and informative display of electromagnetic wave effects in the design of communication systems. More particularly, the present invention supports a modeling technique which facilitates the design of wireless communication systems within buildings, wherein electromagnetic wave “cones” emanating from point sources cover all space without overlap, and electromagnetic effects such as signal coverage are accumulated for display on horizontal planes.
BACKGROUND ART
Presently, indoor wireless communication systems employ radio frequency (RF) antennas located throughout a building complex so that adequate coverage is maintained. When designing such a system for a building complex, the designer must consider signal reflection from and transmission through building structures. Electromagnetic properties of building materials related to reflection and transmission can be measured under controlled conditions and tabulated for the use of designers. Moreover, buildings can be represented as collections of rectangular boxes, with electromagnetic transmission and reflection properties represented by parameter values assigned to box sides. To apply such models to the design of communication systems, computer software is required which can comprehensively display coverage resulting from a given design. Lacking such a tool, it will be appreciated that designers err on the side of including too many antennas operating at excessively high power levels, increasing both the purchase costs and operation costs of communication systems. Even so, there is no practical way to ensure that all necessary signal coverage within a building complex has been attained.
It is known to employ ray tracing, a form of physical optics, in evaluating wireless communication systems as disclosed in U.S. Pat. Nos. 5,491,644 and 5,574,466. The design systems of these disclosures employ ray tracing as part of a validation of wireless communication transfer characteristics. Unfortunately, these systems do not support interactive design of communication systems through comprehensive displays of coverage, because they are limited in the number of receiver test points for which signal coverage can be calculated. A coverage display of sufficient resolution for interactive system design requires thousands of receiver points.
The present limitation on numbers of receiver points is inherent in the method of physical optics employed by systems of the prior art. As taught in the above disclosures, the ray tracing technique employed in these systems works backwards from a receiver point to identify sources and associated signal paths. The calculations must account for rays coming into the receiver point from all possible directions. To do this task for large numbers of receiver points is impractical.
In a communication system design, there are few source points, compared to the number of receiver points desired for display purposes. It is therefore practical to consider rays in all directions emanating from source points. Each ray is considered once, along with each of its subsidiary rays generated by reflections from building walls. Rays are processed in a forward direction from source to receiver. As transmissions and reflections occur, a tree of ray segments is generated, still relatively few in number compared to the number of receiver points. As a ray and its generated ray segments are processed, its effects on each of the receiver points of the coverage display can be accumulated.
An important feature of an interactive design environment is to respond in a timely fashion to small changes in the design. In the backward solving physical optics systems of the present art, all ray processing must be repeated in response to a change of position of any transmitter. In a forward solving system, only the changed transmitter's signal coverage need be computed. To support this feature, it is only necessary to accumulate electromagnetic effects at the receivers separately for each transmitter, combining these effects for each display.
By reliance on backwards construction of ray paths, the present art cannot take into account the relative strength of each transmitter for efficient generation of ray segments in a building complex. Paths must continue until they exhaust the possibility of reaching the strongest transmitter.
The present art does not extend to the forward solving physical optics described above, for lack of solution to certain technical problems which are the subject of the present invention. Specifically, the present art does not teach how to approximate efficiently a spherical signal wave front by a discrete set of approximately equal cones, each representing the local effects of the wave in the neighborhood of a ray. Nor is it taught how to propagate the boundaries of such cones accurately so that discrete contributions of a source to a display point are not missed, nor covered more than once. It has therefore not been taught how to model antenna transmission characteristics within such a system, so as to compute the effects of orientation of transmitters. The present art does not teach how to determine efficiently and accurately which display points are significantly affected by a ray.
These elements, along with provisions for handling reflected as well as transmitted wave propagation within a building, together constitute a system of physical optics which is the subject of the present invention. This system, referred to in this description as the cone mapping method, permits the scientific and empirical knowledge of electromagnetic wave propagation evidenced in the current art to be applied in a timely manner to the computation of displays of signal coverage of a communication system in a building complex.
DISCLOSURE OF INVENTION
Therefore, an object of the present invention is to provide efficient computational techniques enabling signal coverage displays for the interactive design of communication systems within buildings, such design determining adequate placement, orientation and power level of transmitters of a wireless communication system.
Another object of the present invention, as set forth above, is to project signal coverage throughout areas of interest in a building complex, to a resolution required for displays ensuring adequate coverage.
A further object of the present invention, as set forth above, is to represent signal transmission from directionally oriented transmitters to large numbers of receiver test points in a discrete model, without introducing erroneous artifacts of the discrete model through computational inaccuracies.
Still another object of the present invention, as set forth in brief above, is to model each transmitter as a discrete set of rays corresponding to an antenna pattern registered with the modeling program.
Yet another object of the present invention, as set forth above, is to limit the generation of ray segments to those with sufficient strength to affect test receivers significantly.
A further object of the present invention, as set forth above, is to respond interactively to small changes in the design of the communication system being modeled, by computing and maintaining signal coverage values separately for transmitters of the design.
The foregoing and other aspects of the invention, which shall become apparent as the detailed description proceeds, are achieved by a modeling method for determining the signal coverage provided by a wireless communication system of at least one point source such as a transmitter and at least one receiver in a modeled building, comprising the steps of covering completely and without overlap, the space around a point source by a plurality of cones of appropriate size and shape, assigning relative signal strength to each of the plurality of cones based on the angular orientation of a transmitter at the point source and a spherical antenna pattern associated with the transmitter, processing in a forward direction from the point source to the receiver a center ray segment of
Frejd Russell
Renner Kenner Greive Bobak Taylor & Weber
The University of Akron
LandOfFree
Cone mapping physical optics for design of indoor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cone mapping physical optics for design of indoor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cone mapping physical optics for design of indoor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2910784