US 20080014965 A1
A cellular telephone system has call management decisions made based on the exact geographic location of the mobile unit. These call management decisions include billing and taxing decisions, cell site selection, frequency selection and even cellular system selection. The decisions are continuously updated during a call whereby decisions can be made and changed regardless of where a call originated. Cell site location, and even cellular system selection, can be made in a specific manner to best serve the needs of the mobile user, the cellular system as well as the public. It is even possible for a cellular system to locate one or more of its cell sites in the geographic area served by another cellular system. In some cases, cellular systems might even share cell sites.
1. A method of providing emergency call information for a mobile unit, comprising the steps of:
obtaining a mobile unit identification number for the mobile unit via a cellular communication system comprising a plurality of networked antennas in communication with a plurality of mobile units;
acquiring positional data for the mobile unit corresponding to an exact geographic location of the mobile unit via the cellular communication system; and
providing emergency call information to an emergency service, the emergency call information comprising at least the positional data.
2. The method of
3. The method of
storing geographical location data for a plurality of emergency service locations; and
selecting one of the emergency service locations based on a comparison of the positional data to the geographical location data.
4. The method of
5. A method of providing an emergency service for a mobile unit in a cellular communication system comprising a plurality of networked antennas in communication with a plurality of mobile units, comprising the steps of:
acquiring an exact geographic location of a mobile unit in communication with at least one antenna;
designating a provider of an emergency service for the mobile unit based on the exact geographic location; and
routing the exact geographic location to the designated provider.
6. The method of
7. The method of
8. The method of
storing geographical location data for providers of the emergency service; and
comparing the exact geographic location to the geographical location data as a basis to designate the provider of the emergency service.
9. A method of making emergency call decisions in a cellular telephone system having a plurality of cell sites at various geographic locations comprising:
a) providing a mobile unit which can be located at various and changeable geographic locations;
b) receiving a call from the mobile unit requesting emergency service via a cellular telephone system;
c) determining the exact geographic location of the mobile unit from which the call is received;
d) storing geographic data in the cellular telephone system and which are required to complete the call requesting emergency service;
e) comparing the exact geographic location of the mobile unit placing the call requesting emergency service to the stored geographic data; and
f) automatically routing the mobile unit call requesting emergency service to an emergency service based on the comparison regardless of cell site location.
10. The method of
11. A telecommunications system, comprising:
a data storage system for recording a geographic location associated with a mobile unit identification number, and
an updating system responsive to an inaccuracy in the geographic location associated with the mobile unit identification number that exceeds an interval defined by said updating system, and in response thereto updating said data storage system to identify an updated geographic location for said mobile unit identification number, wherein the updated geographic location is an exact geographic location provided to an emergency service.
12. The system of
13. A cellular communications system comprising:
a cellular communication network comprising a plurality of cell sites and a plurality of mobile units, for radio frequency communication between said cell sites and mobile units, at least one of said cell sites receiving an identification of a specific mobile unit, said cellular communication network communicating with said specific mobile unit via a cell site chosen based upon signal strength, and
a positioning system obtaining a position for said specific mobile unit identifying an exact geographic location of the specific mobile unit, and forwarding said exact geographic location and specific mobile unit identification for use in a subsequent service, wherein the subsequent service comprises a plurality of service locations and said exact geographic location is forwarded to one of said service locations based on stored data indicating a geographic location of the mobile unit.
14. The system of
The present application is a divisional of U.S. application Ser. No. 09/662,613 filed Sep. 15, 2000, now allowed, which is a continuation of U.S. application Ser. No. 08/848,082, filed Mar. 21, 1996, now U.S. Pat. No. 6,324,404, which is a continuation-in-part of U.S. application Ser. No. 08/555,884, filed Oct. 23, 1995, now U.S. Pat. No. 5,546,445, which is a continuation-in-part of U.S. application Ser. No. 08/402,976, filed Mar. 13, 1995, now abandoned, which is a continuation of U.S. application Ser. No. 08/057,833, filed May 7, 1993, now abandoned, which is a continuation of U.S. application Ser. No. 07/813,494, filed Dec. 26, 1991 and issued as U.S. Pat. No. 5,235,633. The disclosures of each of these applications is fully incorporated herein by reference. Therefore, as used hereinafter, the term “prior art” refers to art that is relevant prior to the invention dates associated with this incorporated material.
The present invention relates to the general art of wireless over-the-air communication, which includes cellular mobile radiotelephone (CMR) technology, and to the particular field of managing communication processes in a wireless over-the-air communication system.
The present invention is concerned with wireless over-the-air communication using a plurality of transmit/receive cell sites or relay points. It should be understood that the transmit/receive relay points can be either land based or non-land based, such as satellite based, and that as used herein, the term “cell site” or its equivalent refers to one of the relay points of the system. CMR (Cellular Mobile Radio) is an example of one type of wireless over-the-air communication system that can be included in the present disclosure. It is understood that the term CMR is not intended to be limiting, but is merely used as an example for the purposes of discussion. It is also to be understood that the term “cellular telephone system” or its equivalents is intended to be shorthand notation for the term “wireless over-the-air communications system” and no limitation is intended by the use of the term “cellular.” Also, as used herein, the terms “CD (Communication Device)” and “MU (Mobile Unit)” are intended to include any device used to communicate in the wireless over-the-air communication system. Also, the term “cellular telephone system” is used for purposes of discussion but can include any form of wireless over-the-air communication system. It is also noted that many forms of communication are and will be conducted over the wireless over-the-air networks. Therefore, the present disclosure will refer to a “communication process” which is intended to cover calls as well as other forms of communication that can be conducted in this manner.
CMR is a rapidly growing telecommunications system. The typical CMR system includes a multiplicity of cells. A particular geographic area can be subdivided into a multiplicity of subareas, with each of the subareas being serviced by a stationary transmitter/receiver setup. The cells are set up to carry signals to and from mobile units in the range of the cell. If one cell site becomes too crowded, it can be divided into smaller cells, by a process known as cell site splitting. Any particular geographic area can become quite complicated with cells overlapping each other, and overlapping cells of other neighboring cellular systems. Further, null zones with inadequate coverage, or even no coverage, can result. It is noted that the term “cellular” is intended to be a term of convenience, and is not intended to be limiting. The present disclosure is intended to encompass any communication system in which an overall area can be divided into one or more subareas, and also to any communication system having at least some portion of the communications occurring over the air.
A typical CMR set up is indicated in
A typical cellular telephone unit having a unique mobile identification number stored in a suitable location such as an electrically erasable programmable read-only memory (not shown). Telephone units of this kind are known to those skilled in this art, and thus will not be described in detail.
The telephone unit includes a handset 4 having a keypad 5 as well as a speaker 6 and a microphone 7. A transceiver 8, ordinarily built into the telephone unit, exchanges signals via an antenna 10 with a mobile telecommunications switching office or MTSO 12 via a cell site 14. A duplexer 15 connects the antenna to the transceiver. The cell site 14 includes an antenna 16 connected to a control terminal 17 via a transceiver 18. The cell site 14 is connected to the MTSO via a transmission link 20. The Mobile Telephone Switching Office has historically been known as the center of the wireless over-the-air communications system. It is where the communication process management decisions are made, billing records are produced and where maintenance activities are initiated for wireless over-the-air communications systems. The MTSO is not a specific piece of equipment, but is comprised of many individual pieces. The MTSO will contain a telephone switch, peripheral processors, adjunct processors, and various other information gathering equipment used in the operation and management of a wireless over-the-air communications system. Each of the different pieces of equipment may directly or indirectly be involved providing the highest quality connection possible. The makeup of the MTSO therefore comprises many different pieces of equipment and many components, which can be supplied by different vendors. Therefore, communication process management decisions made at the MTSO can actually, be made outside of a switch and can be made in a cluster of nodes housed along the network or even in separate cell sites. Therefore, as used herein the term MTSO really refers to all of the systems, nodes, modules, equipment and components that combine to define a wireless over-the-air communication process management network, regardless of the physical or system location of these elements. The term MTSO therefore is not intended to be limiting to the “switching office” as it may have been viewed in the prior art. The term is intended to be much broader than that and to include any combinations of equipment, etc that may be connected within the communication processing network of the service provider. The term MTSO is one of convenience and is intended to include all the information processing hardware and software associated with the wireless over-the-air communication process management process within a wireless over-the-air system, no matter where the hardware or software is located in the system. It is also noted that the term “intra-system” refers to actions and components within a particular system; whereas, the term “inter-system” refers to actions and components located outside a particular system.
On the other hand, during communication process origination, the mobile unit rescans the control channels to determine which is the best server based on signal strength. Upon selecting the best server, the mobile unit transmits cell site information on the control channel receive frequency and then receives a voice channel to tune to if the mobile unit is authorized to place a communication process.
As the mobile unit moves, the signal strength between that mobile unit and the originating cell site changes, and perhaps diminishes. Since signal strength is an inverse function of the square of the distance between the mobile unit and the cell site, signal strength can change rapidly and drastically as the mobile unit moves with respect to the cell site and therefore must be monitored closely. The MTSO has a signal strength table, and signal strength from the mobile unit is constantly compared to acceptable signal strength levels in the table. Such a table can be located in each cell site if desired.
Should signal strength diminish below a preset range, the MTSO generates a “locate request” signal to all cell sites that neighbor the original cell site. Each of such neighboring cell sites receiving a signal from the mobile unit signals the MTSO, and the signal strengths from such neighboring cell sites are checked against the signal strength table. The MTSO makes a decision as to which cell site should control the communication process, and notifies the original cell site to order the mobile unit to retune to a voice channel of the new cell site.
As soon as the mobile unit retunes, the mobile unit completes the communication process via the new cell site channel. This transfer of control is known as a handoff.
Typically, governments grant rights to provide wireless communication services to a specified land area based on geographic boundaries. Since wireless propagation does not end at exact geographic boundaries, many conflicts have arisen between service providers as to which service provider should provide service at the location from where the Communication Process (CP) is being originated or received. Today, there are no methods or procedures to resolve these issues. A Communication Process (CP) can be defined as the exchange of information between communication devices, such as, but not limited to, Analog or Digital radiotelephones, digital data communications, analog or digital video, and the like.
When the initial wireless systems were built, they were constructed around major metropolitan areas. This created service voids between major metropolitan markets. In these early systems, boundary service problems did not arise because there were areas of “no service” buffering competing systems. Today, as rural systems fill in the patchwork of nationwide coverage, network service provision boundary disputes are becoming common. Prior to the Dennison, et al patent, U.S. Pat. No. 5,235,633 and the patents and applications depending therefrom as continuations and continuations-in-part, the disclosures of which are fully incorporated hereinto by reference, and the invention disclosed herein, it was impossible to honor the exact geographic boundaries. Attempts are currently made to control coverage boundaries by installing directional antennas and adjusting cell site receive and transmit parameters. The methods used to match the system boundaries to the geographic boundaries are not entirely successful due to the variations in terrain, environment and limitations of antenna design and wireless propagation. A common result of these problems is inadequate wireless signal strength or null coverage and border disputes around the geographic boundaries and hence poor service.
The incorporated material, including the Dennison et al patent disclose that cell sites sometimes have overlapping coverage due to the aforementioned variations in terrain and environment, and propose a solution. While the proposed solution works well, there is still room for further improvement in the areas of cost, subscriber service, billing and taxing.
Furthermore, wireless propagation, such as but not limited to the cellular operating band of 800-900 MHz, is generally line-of-site transmission. This presents substantial challenges when choosing sites in which to place wireless transmit/receive antennas. Boundaries assigned to service providers are based on maps depicting the geographic borders of service boundaries. The question arises in a disputed territory of who will get to service the Communications Process (CP). In the past, it has been the cell site that can provide the highest signal strength from the CD (Communications Device), not the provider that owns the legal territorial rights to the Communication Process (CP) that has serviced the Communication Process (CP). Until the invention disclosed herein, the service provider that could receive the best signal would handle the communication process (CP), and depending on whether the Communication Process (CP) was handed off and/or depending on the agreement made between the wireless communication systems, possibly keep all of the revenue from the communication process CP. Additionally, with real estate values being very high in established communities, cell sites are harder to construct and more expensive to build. Each cell site must be optimized for the maximum effective coverage area to overcome the real estate problems encountered when constructing a cell site. This in turn creates problems with overlapping coverage between wireless systems and thus disputes over which wireless system handles the communication process. Further, due to business considerations, it may be economically advantageous for one wireless system to own a cell site which is geographically located in the geographic area of another wireless system.
Cell sites are very expensive to install and maintain, so there is a very real savings for a service provider if fewer cell sites could be constructed while also improving coverage. Another area that would be affected by this is problems of quality service. This is because the service provider has conflicting requirements. To provide good coverage next to borders the provider would like to have high signal strength. To allow for hand-offs between cell sites and networks the signal strength needs to “fade out” at just the right level near the border to invoke a low threshold to start a hand-off process. It would be ideal to have high signal strength right up to a geographic boundary and then drop off beyond that boundary. However, at the present time, presently available systems do not permit this type of coverage.
Some areas inherently have wireless propagation problems, such as service areas next to bodies of water or in steep valleys. Wireless propagation can provide some very undesirable results for a number of reasons, some of which have been mentioned above and in the incorporated material. Therefore, there is a need to provide each network information as to which system has a right to handle a Communications Process (CP). For instance, a communications device (CD) might attempt to select a geographically incorrect service provider. Therefore, there is a need for a system that will permit a service provider to redirect the communication process to the geographically correct service provider, especially in a manner that is transparent to the Communications Device (CD) user.
Since cellular system geographic borders can be non-linear and can have irregular shapes, problems can arise. Problems associated with irregular boundaries are indicated in
Using prior art technology requires installation of directional antennas to minimize the overlap into neighboring territory in order to resolve a border issue. Since these antenna patterns cannot be made to follow curved geographic borders, sectors are installed and directed for the best geographic coverage possible. This often involves obtaining a cell site location close to the border and “shooting back” toward the wireless communication system's own territory. This can leave null zones where cells back onto each other in an effort to keep signals from overlapping into neighboring territory. These null zones will have either poor quality service or even no service at all, thereby resulting in poor service. Therefore, there is a need to overcome this problem as well.
There is also need for providing a wireless over-the-air communication system with the ability to adjust its coverage and billing as the mobile unit moves. This will permit the system to determine taxes based on where the communication process is actually being made as opposed to the criteria used with the prior art. Still further, there is a need to permit a wireless over-the-air communication system to change frequencies as the mobile unit moves whereby a single wireless service provider can provide service to its subscribers regardless of frequency.
Still further, due to various business reasons, a single cell site may advantageously be used by more than one system. It will be necessary to determine which wireless communication system bills the communication process. Prior art systems cannot fully account for this.
Still further, if there is a service problem with a mobile unit, prior art systems are not able to accurately identify the exact geographic location of the unit when the problem arose. This makes it difficult for the network to pinpoint coverage problems. Therefore, there is a need for a wireless over-the-air communication system that permits a wireless communication system to exactly and precisely identify the exact geographic location of a mobile unit when a communication problem occurs.
Still further, with the advent of emergency response networks that use telephones, such as the E-911 systems, there is a need for a wireless over-the-air communication system that can precisely locate a mobile unit and pass that information on to an emergency response system.
The location of an over-the-air system mobile unit making a communication process can also be of use to law enforcement agencies. However, signal strength from one cell site does not provide such location information with sufficient accuracy to be of the best assistance to law enforcement agencies. Therefore, there is a need for an over-the-air communications network that can provide geographic location of a mobile unit during a communication process with accuracy sufficient to satisfy law enforcement agencies. This information should be rapidly updatable so a mobile unit can be tracked.
Since the CMR industry is growing rapidly, competition is growing. Therefore, it is in the best interest of a system to be able to provide the best service possible to its subscribers. One way of achieving this objective is to customize the service to the exact needs of each subscriber. This can be achieved by, among other things, customizing and varying a billing rate plan for each subscriber. That is, the subscriber may be able to pay a lower rate when he is at work than he pays when he or she is at home. Therefore, there is need to a wireless over-the-air communication system that can vary rate plans and vary rates in a manner that will permit offering the best rate plan to each subscriber based on that particular subscriber's use and needs. Still further, some communication processes must be handled in a special manner to account for environmental conditions, or system needs, such as down time for a specific cell. Therefore, even if a communication process should be handled by a certain cell site, there may be times when that communication process must be handled by another cell site. Therefore, there is need for a wireless over-the-air communication system that can account for special circumstances associated with a communication process, and alter the system response when the mobile unit meets the criteria for those circumstances, even if the communication process is already in progress when the criteria are met.
It is a main object of the present invention to provide a wireless over-the-air communications system that will permit a wireless communication system to determine the most efficient and accurate service to a mobile unit.
It is another object of the present invention to provide a wireless over-the-air communications system that will permit a wireless communication system to accurately bill a subscriber.
It is another object of the present invention to provide a wireless over-the-air communications system that will permit a wireless communication system to accurately determine taxes for a subscriber for that subscriber's use of the system.
It is another object of the present invention to provide a wireless over-the-air communications system that will be able to handle all communication processes legally permitted it.
It is another object of the present invention to provide a wireless over-the-air communications system that will be able to handle all communication processes legally permitted it and to forward communication processes that rightfully belong to another wireless communication system while retaining billing and taxing of any portion of the communication process that belongs to it.
It is another object of the present invention to provide a wireless over-the-air communications system that will be able to handle all communication processes legally permitted it based on geographic constraints.
It is another object of the present invention to provide a wireless over-the-air communications system that can bill a subscriber based on the geographic location of communication process origination, and then can update and alter that billing as the mobile unit moves.
It is another object of the present invention to provide a wireless over-the-air communications system that can co-operate with other wireless networks in handling a communication process.
It is another object of the present invention to provide a wireless over-the-air communications system that can share cell sites with other networks while retaining its ability to bill and service its own subscribers.
It is another object of the present invention to provide a wireless over-the-air communications system that can provide the most efficient and effective service to its subscribers and users.
It is another object of the present invention to provide a wireless over-the-air communications system that can update any communication process management parameter to account for instantaneous geographic location of a mobile unit.
It is another object of the present invention to provide a wireless over-the-air communications system that can assign and re-assign a communication process according to the location of the mobile unit during the communication process.
It is another object of the present invention to provide a wireless over-the-air communications system that can share geographic boundaries with other wireless over-the-air service providers without border issues.
It is another object of the present invention to provide a wireless over-the-air communications system that can change and update its operating frequencies during a communication process.
It is another object of the present invention to provide a wireless over-the-air communications system which can have the highest possible signal strength at its borders.
It is another object of the present invention to provide a wireless over-the-air communications system which can identify the location of a mobile unit when a service problem arises.
It is another object of the present invention to provide a wireless over-the-air communications system that can efficiently work with emergency service providers.
It is another object of the present invention to provide a wireless over-the-air communications system that can efficiently implement and utilize special rate plans.
It is another object of the present invention to provide a wireless over-the-air communications system that can efficiently implement and utilize special requirements for a communication process.
It is another object of the present invention to provide a wireless over-the-air communications system that can establish parameters for updating mobile unit information based on the particular needs of the mobile unit.
It is another object of the present invention to provide a wireless over-the-air communications system that can establish time and/or distance parameters for updating mobile unit information based on the particular needs of the mobile unit.
These, and other, objects are achieved by a CMR system that allows the Exact Geographic Location (EGL) of a communications device to be tracked and compared to geographic land data and information data and to continuously update this information during the communication process whereby the proper and most efficient service is provided, including proper communication process management and billing decisions. Within the scope of this invention is the ability to solve the above-mentioned problems and achieve the above-mentioned objects. By knowing the exact geographic location of a mobile unit during a communication process, competing service providers can locate their cell sites anywhere where the wireless reception will allow them to provide the best wireless coverage of their territory. The cell sites can even have overlapping coverage, or be inside an adjacent wireless communication system's coverage area. By knowing the location of the calling device at all times during the communication process, the wireless over-the-air communication system can configure the system to work together with other systems and wireless communication systems to process a communication process correctly. Service can be provided by the proper licensed wireless communication system because the exact location of the mobile unit is known at all times during the communication process. Propagation patterns and the like are not needed.
By way of background, the operation of a cellular system 20 is shown in
The means for accurately determining the precise position of the mobile unit includes a Global Positioning System. The GPS includes satellites, such as satellite 22 in geostationary orbit about the earth. Each mobile unit further includes a GPS receiver 24 located between the duplexer and the logic circuitry 25 of the mobile unit. The GPS receiver communicates with the satellite 22 and the exact longitude and latitude of the mobile unit are determined. This information is sent to the MTSO via a cell site, and the MTSO uses a look-up table such as disclosed in
The handoff process is similar to the present hand-off processes, except it will be controlled according to position of the mobile unit instead of signal strength. This position information is used to determine communication process rating and taxing for billing purposes and communication process routing to make sure that the proper services for that location are provided.
A “locate request” signal is not used, since the exact location of the mobile unit is known to the MTSO. However, a signal strength method can also be used in making communication process management decisions if suitable. Such a process would be used if the mobile unit moves into a prior art cellular system.
The hereinafter disclosed system has many advantages over the prior art systems. Multiple layers of information can be generated and used. The system using the invention disclosed herein and in the incorporated material may use many levels of mapping such as cell site selection, taxing, billing, special rate plans, and the mapping of E-911 calls to an appropriate service provider.
The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
A representation of the logical flow that may occur in a wireless communications system incorporating the use of exact geographic location (EGL) for the communication process management decisions is shown in
When a communications device is powered up, block 101, the registration process, block 102 is initiated. The registration process is detailed in
If a Communication Process (CP) were initiated then the registration process, block 106,
With communications established (
The cell site can re-direct a communication process to another cell site under certain circumstances. For example, even though a particular cell site is chosen to handle a communication process, there may be special circumstances associated with a particular location that dictate all communication processes from that location be handled by a certain cell site. Special environmental conditions may be one such special circumstance, cell sites under repair may be another special circumstance or other business reasons may dictate such re-directing of communication processes. This redirecting can also occur for cellular systems. That is, if a selected cell site is not owned by the cellular system having rights to the communication process made by the mobile unit at that particular location, the communication process could be redirected to another cellular system. In this manner, customization of cellular service can be maximized with billing, taxing, frequency and the like all being selected according to the exact needs of the mobile unit during the communication process, and changed as the needs of the mobile unit change during the communication process. As discussed above, the preferred means for establishing the exact geographic location of the mobile unit includes a satellite communications system; however, other means can also be used.
All of this data collection and monitoring continues until the Communication Process (CP) is completed, block 117. When the Communication Process (CP) is complete, and exact geographic location (EGL) of the mobile unit is recorded for various data processing uses prior to the data record closure, block 118.
In the present system, the wireless communication system will obtain the instant location of the Communications Device (CD) at the registration process (
If needed, the billing location codes could be recorded at some given interval (perhaps, for example, every minute, or after the mobile unit has traveled a certain distance) that would allow for updates and changes to the billing code as the Communications Device (CD) moves through different territories or beyond interval distances which can be calculated directly in a GPS system or indirectly via vector calculations in other systems.
One of the additional features that can be provided by the system of the present invention is real time subscriber service (
Although billing and taxing issues are important to current land based wireless communications systems service providers, these issues will be even more important for satellite systems (see
The advantages realized by the present invention can also be understood by comparing
Therefore, as can be seen from the figures, if the provider were to increase the signal strength in an area, it may result in more overlap. This overlap is not a problem with the inventive system since the service boundaries are mapped to the exact geographic location (EGL) of the communications device (CD).
An example of another advantage realized with the present system is that all communication processes may be processed through the tax data base, but the wireless communication system may have a select group of subscribers that are identified to pay a certain billing rate in a specified geographic area which would constitute an additional loop through another look-up table. For example, as indicated in
Still another application for the technology of this invention could encompass the switching of a dual frequency phone to a second frequency based on exact geographic location (EGL) of the communication device (CD). An example of this would be switching from 800-900 MHz to 2 GHz frequencies used in the upcoming PCS system. This would be useful for the commuter who wants PCS for his Communications Device (CD) in the city and to be able to roam out of PCS territory into cellular territory. It may even come to the time when subscribers are given rate plans that correspond to different zones, such as a 2000 foot perimeter of their residence which would be billed at a residence rate, and be billed at a Home market rate beyond that. Still further, when the subscriber enters into the geographic zone of his or her employer, the MTSO will forward his business communication processes to his communication device (CD), all based on his present exact geographic location. This could be an important competitive advantage to a service provider that owned the 900 MHz in one area and the 2000 MHz rights in a second area. For example,
The preferred means for establishing exact geographic location (EGL) is a satellite communication system such as discussed in the incorporated material. However, other means, including, but not limited to, triangulation and the like, can be used without departing from the scope of the present invention.
It is understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts described and shown.
While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.