BACKGROUND

Field

[0001] Embodiments of the present invention generally relate to radio communications and, in particular, to a method and apparatus for performing position location using cellular signals.

Description of the Related Art

[0002] Cellular telephone networks are designed as a network of interconnected cells where each cell has a centrally located tower or other structure supporting antennas for an emitter that communicate with mobile transceivers operating in a 0.1 to 10 km radius. In many instances, the antennas have stationary positions upon tall buildings, water towers, telephone poles, light poles or any structure with substantial height to form a cellular mast.

[0003] Cellular signal transceivers (handsets) send and receive signals to/from cellular base stations to facilitate data and voice communications between handsets. In some instances, the cellular transceiver may be used to estimate the position of the handset. Typically, such positioning requires a transceiver with multiple antennas and reception of signals from at least three base stations that are received in a low multipath environment, e.g., open space without buildings or other objects proximate the transceiver. The transceiver also requires knowledge of the location of the cellular base station antennas. In such a situation, the transceiver receives the cellular signals and can use code phase or carrier phase computations to compute the transceiver’s location relative to the base station antenna locations.

[0004] Unfortunately, most handset have a single antenna and most environments where handsets are used experience a substantial amount of multipath interference. In these situations, a handset cannot determine its position in an accurate way using cellular signals. [0005] Sometimes it is possible to determine an accurate position using other radio signals such as GNSS signals. However, these signals may not always be available, especially if the receiver is in a challenging positioning environment, such as indoors.

[0006] Therefore, there is a need for a method and apparatus for performing more accurate position location using cellular signals.

SUMMARY

[0007] Embodiments of the present invention generally relate to a method and apparatus for performing position location using cellular signals as shown in and/or described in connection with at least one of the figures.

[0008] According to an aspect of the invention there is provided a method for locating a receiver using cellular signals, comprising: performing motion compensated correlation upon a plurality of received signals transmitted from at least one cellular signal base station transceiver to generate at least one motion compensated correlation result; identifying a direction of arrival for each received signal in the plurality of received signals using the at least one motion compensated correlation result; and determining, using the direction of arrival of the plurality of received signals, a location of the receiver.

[0009] In this way, a location of the receiver can be determined based only on direction of arrival information for cellular signals. According to this technique it is possible to determine an accurate position even if one or more of the received signals has been reflected from potentially unknown surfaces. Equally, it is possible to determine a position even the location of the emitters is not known accurately or if signals are received from only one emitter. This can advantageously improve a receiver’s knowledge of position in an urban environment in the absence of conventional positioning signals, such as GNSS signals.

[0010] In some arrangements motion compensated correlation may be performed on cellular signals received from a plurality of cellular signal base stations. In this way, the determined location of the receiver can be based on cellular signals from multiple base stations. This technique may be most suitable when the receiver is able to communicate with base stations having a longer range. It may be possible to determine a more accurate position when signals are received from cellular signal base stations in a spread of two-dimensional directions.

[0011] In some configurations motion compensated correlation may be performed on a plurality of received signals from a single cellular base station. The plurality of received signals may include one or more reflected signals having different directions of arrival. The plurality of received signals may also include an unreflected signal that is received directly along the line-of-sight direction between the receiver and the cellular signal base station. A mixture of different signals from one or more cellular base stations may be used, including direct signals and reflected signals.

[0012] The determining step may also be based on data for the position of the at least one cellular signal base station transceiver. The receiver may include a data storage unit comprising a database of known positions for one or more cellular signal base station transceivers. In addition, the determining step may be based on the position of one or more known reflecting surfaces such as may be determined from a 3D building model. In this way, it may be possible to determine the location of the receiver based on the direction of arrival of signals from one or more known reflecting surfaces, which have known positions.

[0013] The method may be based on any kind of cellular signal such as 3G, 4G or 5G. Additionally, more than one kind of cellular signal may be processed by the receiver in parallel in accordance with the claimed method.

[0014] The location of the receiver may be performed for a plurality of time periods to determine a plurality of positions for a moving receiver.

[0015] The step of determining the location of the receiver may also be based on calculated ranges or determined path lengths for the received signals transmitted from the at least one cellular signal base station transceiver. Ranges or path lengths may be calculated using time of arrival (TOA), time difference of arrival (TDOA) or other known techniques for cellular signals.

[0016] According to another aspect of the invention there is provided an apparatus for performing positioning of a receiver, comprising at least one processor and at least one non-transient computer readable medium for storing instructions that, when executed by the at least one processor, causes the apparatus to perform operations comprising: performing motion compensated correlation upon a plurality of received signals transmitted from at least one cellular signal base station transceiver to generate at least one motion compensated correlation result; identifying a direction of arrival for each received signal in the plurality of received signals using the at least one motion compensated correlation result; and determining, using the direction of arrival of the plurality of received signals, a location of the receiver.

[0017] These and other features and advantages of the present disclosure may be appreciated from a review of the following detailed description of the present disclosure, along with the accompanying figures in which like reference numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] So that the manner in which the above recited features of the present invention can be understood in detail, a particular description of the invention, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0019] FIG. 1 depicts a block diagram of a scenario having a receiver for receiving cellular signals and performing position location in accordance with at least one embodiment of the invention;

[0020] FIG. 2 is a block diagram of the receiver in accordance with at least one embodiment of the invention; [0021] FIG. 3 depicts a scenario of operation of the receiver of FIGs. 1 and 2 in accordance with at least one embodiment of the invention;

[0022] FIG. 4 is a flow diagram of a method of operation for the signal processing software in accordance with at least one embodiment of the invention; and

[0023] FIG. 5 is a flow diagram of a method of operation of the location software in accordance with at least one embodiment of the invention.

DETAILED DESCRIPTION

[0024] Embodiments of the present invention comprise apparatus and methods for performing position location using cellular signals. Cellular telephone systems utilize digital signals to improve communication throughput and security. Most of these systems utilize some form of deterministic digital code to facilitate signal acquisition, e.g., Gold codes, training sequences, synchronization words, or channel characterization sequences. Such a digital code is deterministic by the receiver and repeatedly broadcast by the transmitter to enable communications receivers to acquire and receive the transmitted signals. Using such deterministic codes combined with an accurate motion model of the receiver, embodiments of the invention are useful for identifying a direction of arrival (DoA) for a propagation path between the receiver and transmitter. The technique for performing this DoA determination using receiver motion information is known as SUPERCORRELATION™ and is described in commonly assigned US patent 9,780,829, issued 3 October 2017; US patent 10,321 ,430, issued 11 June 2019; US patent 10,816,672, issued 27 October 2020; US patent publication 2020/0264317, published 20 August 2020; and US patent publication 2020/0319347, published 8 October 2020, which are hereby incorporated herein by reference in their entireties. From the known location of the cellular signal transmitters, the receiver may use this DoA data to compute the location of the receiver.

[0025] For example, a receiver may be transported through an area containing cellular emitters and be able to compute its position from the cellular signals even when the receiver has a single antenna and/or in a multipath environment. The receiver may be carried by pedestrians and be made functional via application software to perform position location. Alternatively, position location may be performed by moving the receiver using a vehicle on a ground path. In other embodiments, the receiver may be carried by an airborne vehicle - manned or unmanned (e.g., drones, helicopters, airplanes, etc.).

[0026] As the receiver traverses an area, it collects DoA data for the cellular emitters that are nearby (i.e. , within range of the emitter). The distance to the emitter varies depending upon the cellular standard used by the emitter. For example, a 3G based emitter may be received up to 50 km from an emitter, while a 5G based emitter may be received only 100 m from the emitter. The receiver may not know its position or may have an estimate of its position from a global navigation satellite system (GNSS) receiver and/or an inertial guidance system. The receiver has a database of cellular emitter locations. From the emitter position and a plurality of DoA vectors (representing direction from receiver to emitter) to a particular emitter, embodiments of the invention compute the location of the receiver relative to the cellular emitter. The relative location can then be translated to a geocoordinate. The receiver position determine from cellular signals may be used to augment the accuracy of a GNSS receiver position or inertial guidance system position. Such position assistance is especially useful in environments having substantial multipath, e.g., urban canyons where the environment contains buildings and other signal reflective objects.

[0027] FIG. 1 depicts a block diagram of a scenario 100 having a receiver 102 for performing position location using cellular signals transmitted from cellular emitters 106, 108 and 110 in accordance with at least one embodiment of the invention. An emitter comprises cellular transceiver 124, a mast 126, and an antenna 128 operating together as a conventional, fixed location cellular base station. The receiver 102 comprises a positioning unit 104 configured to receive and process signals transmitted by cellular emitters 106, 108, 110 (three emitters are depicted, but the receiver 102 may process the signals from any number of emitters). The signals from the emitters 106, 108 and 110 are intended to communicate with a standard cellular mobile device 120, e.g., cellular telephone, laptop computer, tablets, Internet of Things (loT) devices, etc. that communicate using cellular signals, e.g., CDMA, GSM and the like that support cellular standards such as, but not limited to, 3G, 4G, LTE, and/or 5G standards. The receiver 102 may be a portion of a cellular mobile device, such as device 120, or may be a standalone positioning receiver operating in accordance with at least one embodiment of the invention to determine its position using received cellular signals.

[0028] The receiver 102 comprises an emitter position database 122 and a positioning unit 104 operating to accurately locate the receiver 102 based upon reception of signals 112, 114 and 116 transmitted from emitters 106, 108, 110 in accordance with at least one embodiment of the invention. As described in detail below, the positioning unit 104 uses a SUPERCORRELATION™ technique as described in commonly assigned US patent 9,780,829, issued 3 October 2017; US patent 10,321 ,430, issued 11 June 2019; US patent 10,816,672, issued 27 October 2020; US patent publication 2020/0264317, published 20 August 2020; and US patent publication 2020/0319347, published 8 October 2020, which are hereby incorporated herein by reference in their entireties. The technique determines a direction of arrival (DoA) of received signals 112, 114, 116. As the receiver 102 moves (represented by arrow 118), the positioning unit 104 computes motion information representing motion of the receiver 102. The motion information is used to perform motion compensated correlation of the received signals 112, 114, 116. From the motion compensated correlation process, the emitter locator 104 estimates the DoA of the signals 112, 114, 116. The emitter database 122 provides an accurate location for the emitters 106, 108, 110. The positioning unit 104 uses the emitter positions along with the DoA data to determine a location of the receiver 102. The intersection of a plurality of DoA vectors generated as the receiver moves along path 118 identifies the location of the receiver 102 as described in detail below.

[0029] In alternative embodiments, the received signals may be processed to determine time of arrival (TOA) or time difference of arrival (TDOA) information for the received signals. As is known in the art, the TOA and TDOA information may be used for position calculations of the receiver by calculating ranges from the receiver to the emitter(s). As described below, such calculations may be used to augment the DoA vector processing to improve the speed at which a position solution is attained.

[0030] FIG. 2 is a block diagram of the receiver 102 in accordance with at least one embodiment of the invention. The receiver 102 comprises a mobile platform 200, an antenna 202, receiver front end 204, signal processor 206, and motion module 228. The receiver 102 may form a portion of a laptop computer, mobile phone, tablet computer, Internet of Things (loT) device, unmanned aerial vehicle, mobile computing system in an autonomous vehicle, human operated vehicle, etc.

[0031] In the receiver 102, the mobile platform 200 and the antenna 202 are an indivisible unit where the antenna 202 moves with the mobile platform 200. The operation of the SUPERCORRELATION™ technique operates based upon determining the motion of the signal receiving antenna. Any mention of motion herein refers to the motion of the antenna 202. In some embodiments, the antenna 202 may be separate from the mobile platform 200. In such a situation, the motion estimate used in the motion compensated correlation process is the motion of the antenna 202. In most scenarios, the motion of the mobile platform 200 is the same as the motion of the antenna 202 and, as such, the following description will assume that the motion of the platform 200 and antenna 202 are the same.

[0032] The mobile platform 200 comprises a receiver front end 204, a signal processor 206 and a motion module 228. The receiver front end 204 downconverts, filters, and samples (digitizes) the received signals in a manner that is well-known to those skilled in the art. The output of the receiver front end 204 is a digital signal containing data. The data of interest is a deterministic training or acquisition code, e.g., Gold code, used by the cellular emitter to synchronize the transmission to a cellular transceiver.

[0033] The signal processor 206 comprises at least one processor 210, support circuits 212 and memory 214. The at least one processor 210 may be any form of processor or combination of processors including, but not limited to, central processing units, microprocessors, microcontrollers, field programmable gate arrays, graphics processing units, digital signal processors, and the like. The support circuits 212 may comprise well-known circuits and devices facilitating functionality of the processor(s). The support circuits 212 may comprise one or more of, or a combination of, power supplies, clock circuits, analog-to-digital converters, communications circuits, cache, displays, and/or the like.

[0034] The memory 214 comprises one or more forms of non-transitory computer readable media including one or more of, or any combination of, read-only memory or random-access memory. The memory 214 stores software and data including, for example, signal processing software 216, positioning software 208 and data 218. The data 218 comprises the receiver location 220, direction of arrival (DOA) vectors 222 (collectively, DoA data), emitter locations 224, and various data used to perform the SUPERCORRELATION™ processing. The signal processing software 216, when executed by the one or more processors 210, performs motion compensated correlation upon the received signals to estimate the DoA vectors for the received signals. The motion compensated correlation process is described in detail below. The operation of the signal processing software 216 and positioning software 208 function as the positioning unit 104 of FIG. 1.

[0035] As described below in detail, the DoA vectors 222 and emitter locations 224 are used by the positioning software 208 to determine the location of the receiver 102. The data 218 stored in memory 214 may also include signal estimates, correlation results, motion compensation information, motion information, motion and other parameter hypotheses, position information and the like.

[0036] The motion module 228 generates a motion estimate for the receiver 102. The motion module 228 may comprise an inertial navigation system (INS) 230 as well as a global navigation satellite system (GNSS) receiver 226 such as GPS, GLONASS, GALILEO, BEIDOU, etc. The INS 230 may comprise one or more of, but not limited to, a gyroscope, a magnetometer, an accelerometer, and the like. To facilitate motion compensated correlation, the motion module 228 produces motion information (sometimes referred to as a motion model) comprising at least a velocity of the antenna 202 in the direction of an emitter of interest, i.e. , an estimated direction of a source of a received signal. In some embodiments, the motion information may also comprise estimates of platform orientation or heading including, but not limited to, pitch, roll and yaw of the platform 200/antenna 202. Generally, the receiver 102 may test every direction and iteratively narrow the search to one or more directions of interest.

[0037] FIG. 3 depicts a scenario 300 of operation of the receiver 102 of FIGs. 1 and 2 in accordance with at least one embodiment of the invention. The scenario 300 comprises the receiver 102 moving from position 1 along path 302 to position 2, and then moving along path 304 to position 3. As the receiver 102 traverses the area, the receiver 102 computes a DoA vectors 306, 305, 310 at position 1 , 312, 314, 316 at position 2 and 318, 320, 322 at position 3. The three DoA vectors 306, 305 and 310 intersect at the location of the receiver 102. Although three discrete positions are described as where the DoA vectors are computed, in other embodiments, the DoA vectors may be computed periodically, intermittently or continuously as the receiver moves. Additional vectors may be used to converge the solution onto an accurate receiver location.

[0038] In an urban environment, some DoA vectors 306, 305, 310 are line-of-sight (LOS) and some DoA vectors 324 are non-line-of-sight (NLOS), i.e., LOS vectors represent signals that are transmitted directly from the emitter 106 to the receiver 102, while NLOS vectors may be reflected from structures 316 in the vicinity of the receiver 102. As more and more DoA vectors are collected and processed, the LOS vectors converge on a particular location. In addition, if TOA or TDOA information is available, the information may be used to remove DoA vectors of NLOS paths because the arrival times will be anomalous (delayed) for the NLOS signals versus the LOS signals, i.e., the time information of NLOS signals will contain a delay compared to the LOS signals.

[0039] In other embodiments, the structures 316 may be modeled in a building model. The building model in conjunction with ray tracing techniques can be used to determine the DoA of reflected signals, based on the known position of the reflection surface 316. Consequently, the path of the reflected emitter signal is estimated and the reflected signals may be used in the receiver localization calculation. If a 3D model of an area is available, the receiver 102 may compute its position using the reflected signals as being sourced from virtual transmitters 326 located at the image point of the reflected signals (as shown schematically in Figure 3). In an alternative embodiment, a plurality of reflected signals (or even a single reflected signal) and a direct signal from a single cellular base station may be used to compute the receiver position.

[0040] In other embodiments, one or more receivers 102 may collect all emitter signals, LOS and NLOS, over a period of time while the receivers are traversing an area. These collected signals may be processed using the receiver localization techniques described herein. The signal formula will contain DoA vector intersection regions that identify receiver locations. In some embodiments, a Baysian estimator may be used to compare various hypotheses as to receiver location using information provided by available measurements.

[0041] Typically, vector intersection location is not a point, but rather it is a region or area due to the probabilistic nature of the DoA vectors, i.e. , the determined direction of each vector has an uncertainty caused by measurement error and the intersection forms a region rather than a point. The region may have a two-dimensional probabilistic spread with a maximum that defines the most likely location of the receiver 102.

[0042] Since the emitters have known locations, the geolocation coordinates of the emitters may be translated into a geolocation coordinates for the receiver 102. As such, a geolocation map of sequentially generated receiver locations may be produced.

[0043] The forgoing embodiment performs the DoA vector and receiver location determination within the receiver 102. In other embodiments, the data for producing DoA vectors, DoA vectors themselves, position information, etc. may be transmitted from the receiver to a server (not shown) for processing to produce the receiver locations. [0044] FIG. 4 is a flow diagram of a method 400 of operation for the signal processing software 216 in accordance with at least one embodiment of the invention. The method 400 may be implemented in software, hardware or a combination of both (e.g., using the signal processor 206 of FIG. 2).

[0045] The method 400 begins at 402 and proceeds to 404 where signals are received at a receiver from at least one remote source (e.g., transmitters such as the emitters 106, 108, 110 of FIG. 1 ) in a manner as described with respect to FIG. 1. Each received signal comprises a synchronization or acquisition code, e.g., a Gold code, extracted from the radio frequency (RF) signal received at the antenna. The process of downconverting the RF signal and extracting the digital code is well known in the art. At 406, the method 400 receives motion information from the motion module 228 of FIG. 2. The motion information comprises an estimate of the motion of the receiver 102 of FIG. 1 , e.g., one or more of velocity, heading, orientation, etc.

[0046] At 408, the method 400 generates a plurality of phasor sequence hypotheses related to a direction of interest of the received signal (i.e., direction toward an emitter). Each phasor sequence hypothesis comprises a time series of phase offset estimates that vary with parameters such as receiver motion, frequency, DoA of the received signals, and the like. The signal processing correlates a local code encoded in a local signal with the same code encoded within the received RF signal. In one embodiment, the phasor sequence hypotheses are used to adjust, at a sub-wavelength accuracy, the carrier phase of the local signal. In some embodiments, such adjustment or compensation may be performed by adjusting a local oscillator signal, the received signal(s), or the correlation result to produce a phase compensated correlation result. The signals and/or correlation results are complex signals comprising in-phase (I) and quadrature phase (Q) components. The method applies each phase offset in the phasor sequence to a corresponding complex sample in the signals or correlation results. If the phase adjustment includes an adjustment for a component of receiver motion in an estimated direction of the emitter, then the result is a motion compensated correlation result. For each received signal, at 410, the method 400 correlates the received signals with a set (plurality) of direction hypotheses containing estimates of the phase offset sequences necessary to accurately correlate the received signals over a long coherent integration period (e.g., 1 second). There is a set of hypotheses representing a search space for each received signal.

[0047] The motion estimates are typically hypotheses of the receiver motion in a direction of interest such as in the direction of the emitter that transmitted the received signal. At initialization, the direction of interest may be unknown or inaccurately estimated. Consequently, a brute force search technique may be used to identify one or more directions of interest by searching over all directions and correlating signals received in all directions. A comparison of correlation results over all the directions enables the method 400 to narrow the search space. There is very strong correlation between the true values of these hypotheses between code repetition, such that the initial search might be intensive, but subsequent processing only requires tracking of the parameters in the receiver as they evolve. Consequently, subsequent compensation is performed over a narrow search space.

[0048] In one embodiment, if a signal from a given emitter was received previously, the set of hypotheses for the newly received signal include a group of phasor sequence hypotheses using the expected Doppler and Doppler rate and/or last Doppler and last Doppler rate used in receiving the prior signal from that particular emitter. The values may be centered around the last values used or the last values used additionally offset by a prediction of further offset based on the expected receiver motion. At 410, the method 400 correlates each received signal with that signal’s set of hypotheses. The hypotheses are used as parameters to form the phase- compensated phasors to phase compensate the correlation process. As such, the phase compensation may be applied to the received signals, the local frequency source (e.g., an oscillator), or the correlation result values. In addition to searching over the DoA, the method 400 may also apply hypotheses related to other variables (parameters) such as oscillator frequency to correct frequency and/or phase drift (if not previously corrected), or heading to ensure the correct motion compensation is being applied. The number of hypotheses may not be the same for each variable. For example, the search space may contain ten hypotheses for searching DoA and have two hypotheses for searching a receiver motion parameter such as velocity - i.e. a total of twenty hypotheses (ten multiplied by two). The result of the correlation process is a plurality of phase-compensated correlation results - one phase-compensated correlation result value for each hypothesis for each received signal.

[0049] At 412, the method 400 processes the correlation results to find the “best” or optimal result for each received signal. The correlation output may be a single value that represents the parameter hypotheses (preferred hypotheses) that provide an optimal or best correlation output. In general, a cost function is applied to the correlation values for each received signal to find the optimal correlation output corresponding to a preferred hypothesis or hypotheses, e.g., a maximum correlation value is associated with the preferred hypothesis for the correct signal DoA.

[0050] At 414, the method 400 identifies the DoA vector of each received signal from the optimal correlation result for the signal. The received signals along the DoA vector typically have the strongest signal to noise ratio and represent line of sight (LOS) reception between the emitter and receiver. As such, using motion compensated correlation enables the receiver 102 to identify the DoA vector of the received signal(s). The method 400 ends at 416.

[0051] In other embodiments, rather than using the largest magnitude correlation value, other test criteria may be used. For example, the method 400 may monitor the progression of correlations as hypotheses are tested and apply a cost function that indicates the best hypotheses when the cost function reaches a minimum (e.g., a small hamming distance amongst peaks in the correlation plots). In other embodiments, additional hypotheses may be tested in addition to the DoA hypotheses to, for example, ensure the motion compensation (i.e., speed and heading) is correct.

[0052] FIG. 5 is a flow diagram of a method 500 of operation of the positioning software 208 in accordance with at least one embodiment of the invention. The method 500 may be performed locally within the receiver or may be performed remotely on a server. If performed remotely, the DoA vectors and/or data to generate the DoA vectors are transmitted from the receiver to a remote server for processing in accordance with method 500.

[0053] The method 500 begins at 502 and proceeds to 504 where the method 500 receives the DoA vectors for a plurality of emitters. At 506, the method 500 determines a location where the DoA vectors intersect. The receiver location is relative to the emitter positions. The process may be iterative as additional DoA vectors are generated or may be calculated when a predefined number (e.g., three, five, ten, etc.) of DoA vectors have been determined. In some embodiments, the position computation may be augmented using TOA or TDOA information. For example, the time information related to the time a signal is received at various receiver positions can be used to identify LOS signals versus NLOS signals, e.g., NLOS signals have a delayed reception time as compared to LOS signals. DoA vectors associated with NLOS signals may then be removed from the vector set used to determine receiver location. In some other embodiments TOA or TDOA information may be utilized to calculate ranges from the receiver to the emitter(s).

[0054] At 508, the method 500 computes geolocation coordinates for the receiver location by translating the known geolocation coordinates of the emitters to the receiver location determined at 506. The geolocation for the receiver location may be further constrained based on the ranges that are calculated using TOA or TDOA information. In addition, other signals of opportunity such as available GNSS signals may be used as inputs in a positioning calculation. At 510, the method queries whether another set of DoA vectors for emitter signals received by the receiver at a new location are available for processing. If the query is affirmatively answered, the method 500 returns to 504 to process additional DoA vectors. If the query is negatively answered, the method 500 ends at 512.

[0055] Here multiple examples have been given to illustrate various features and are not intended to be so limiting. Any one or more of the features may not be limited to the particular examples presented herein, regardless of any order, combination, or connections described. In fact, it should be understood that any combination of the features and/or elements described by way of example above are contemplated, including any variation or modification which is not enumerated, but capable of achieving the same. Unless otherwise stated, any one or more of the features may be combined in any order.

[0056] As above, figures are presented herein for illustrative purposes and are not meant to impose any structural limitations, unless otherwise specified. Various modifications to any of the structures shown in the figures are contemplated to be within the scope of the invention presented herein. The invention is not intended to be limited to any scope of claim language.

[0057] Where “coupling” or “connection” is used, unless otherwise specified, no limitation is implied that the coupling or connection be restricted to a physical coupling or connection and, instead, should be read to include communicative couplings, including wireless transmissions and protocols.

[0058] Any block, step, module, or otherwise described herein may represent one or more instructions which can be stored on a non-transitory computer readable media as software and/or performed by hardware. Any such block, module, step, or otherwise can be performed by various software and/or hardware combinations in a manner which may be automated, including the use of specialized hardware designed to achieve such a purpose. As above, any number of blocks, steps, or modules may be performed in any order or not at all, including substantially simultaneously, i.e., within tolerances of the systems executing the block, step, or module.

[0059] Where conditional language is used, including, but not limited to, “can,” “could,” “may” or “might,” it should be understood that the associated features or elements are not required. As such, where conditional language is used, the elements and/or features should be understood as being optionally present in at least some examples, and not necessarily conditioned upon anything, unless otherwise specified.

[0060] Where lists are enumerated in the alternative or conjunctive (e.g., one or more of A, B, and/or C), unless stated otherwise, it is understood to include one or more of each element, including any one or more combinations of any number of the enumerated elements (e.g. A, AB, AC, ABC, ABB, etc.). When “and/or” is used, it should be understood that the elements may be joined in the alternative or conjunctive.

[0061] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.