Patent ID: 12227290

DETAILED DESCRIPTION

Techniques disclosed herein relate generally to an electrically powered aircraft including a plurality of tilting electric propulsion systems. More specifically, techniques disclosed herein provide a power distribution system including a plurality of isolated power distribution circuits that are coupled to separate batteries via contactors. Each power distribution circuit supplies power to a plurality of balanced electric propulsion systems so a power system failure results in a stable change in speed or altitude of the aircraft, but no rotation. Various inventive embodiments are described herein, including methods, processes, systems, devices, and the like.

In order to better appreciate the features and aspects of the power distribution systems for electrically powered aircraft according to the present disclosure, further context for the disclosure is provided in the following section by discussing particular implementations of an electrically powered vertical takeoff and landing (VTOL) aircraft according to embodiments of the present disclosure. These embodiments are for example only and power distribution systems can be employed in other types of electrically powered vehicles than those depicted herein.

Several illustrative embodiments will now be described with respect to the accompanying drawings, which form a part hereof. The ensuing description provides embodiment(s) only and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the ensuing description of the embodiment(s) will provide those skilled in the art with an enabling description for implementing one or more embodiments. It is understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of this disclosure. In the following description, for the purposes of explanation, specific details are set forth in order to provide a thorough understanding of certain inventive embodiments. However, it will be apparent that various embodiments may be practiced without these specific details. The figures and description are not intended to be restrictive. The word “example” or “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” or “example” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

FIGS.1A and1Bdepict simplified isometric drawings of an electrically powered VTOL aircraft100with twelve tilting electronic propulsion systems105(1)-105(12), according to embodiments of the disclosure. More specifically,FIG.1Adepicts aircraft100in a vertical flight configuration andFIG.1Bdepicts aircraft100in a horizontal flight configuration.

As shown inFIGS.1A and1B, in some embodiments, aircraft100may be configured to carry one or more passengers and/or cargo, and may be controlled automatically and/or remotely (e.g. may not require an on-board pilot to operate the aircraft). In the example shown, aircraft100includes a fuselage110that may include a cabin section for carrying passengers and/or cargo. Propulsion systems105(1)-105(12) may be mounted on opposite ends of booms115. One or more booms115may be coupled to each wing120,125of the aircraft100to enable aircraft100to have any number of propulsion systems105. For example, each wing120,125may include three booms115, with each boom including a pair of tilting electronic propulsion systems105mounted thereon.

Aircraft100is illustrated inFIGS.1A and1Busing three mutually perpendicular coordinate axes X, Y and Z, at the intersection of which is the aircraft center of gravity (CG)130. Aircraft100has six degrees of freedom including forces in each coordinate axis direction Fx, Fy, Fz and moments about each coordinate axis Mx, My, Mz. Aircraft100includes a left wing125opposite a right wing120which are both attached to fuselage110. In this embodiment propulsion systems105are distributed along each wing120,125with an equal number on left wing125, an equal number on right wing120, an equal number in front of each wing and an equal number behind each wing. The equal distribution of propulsion systems105about CG130of aircraft100enables straight and level flight by applying equal power to each propulsion system due to all forces applied by each propulsion system being balanced about the CG. Of course, changes in applied forces and moments can be controlled by changing power supplied to one or more of propulsion systems105.

Aircraft100includes a power distribution system (not shown inFIGS.1A and1B) that delivers power from a plurality of batteries to each propulsion system105, as described in more detail below. In one embodiment, each power distribution circuit includes at least two propulsion systems105that are balanced about CG130so that if the power distribution circuit fails, the forces applied to the aircraft from the propulsion systems are balanced about the CG. For example propulsion systems105(1) and105(12) may be on one power distribution circuit and propulsion systems105(6) and105(7) may be on a different power distribution circuit.

If either power distribution circuit fails, for example in the configuration shown inFIG.1A, aircraft100will only experience a change in force along the Z axis (Fz) and there will be no change in other forces or moments (Fx, Fy, Mx, My or Mz) so the aircraft will at most change altitude but will not pitch or roll. Other examples of balanced propulsion systems are2,11;5,8;3,10;4,9;1,6,7,12;2,5,8,11and3,4,9,10in addition to others. One of ordinary skill the art will appreciate that the number and location of the electronic propulsion systems105is not limited to that illustrated inFIGS.1A-1Band that an aircraft can include less or more propulsion systems, provided at other positions on the aircraft, etc.

FIG.2illustrates a simplified power distribution system200for aircraft100illustrated inFIGS.1A and1B. As shown inFIG.2, power distribution system200includes twelve isolated power distribution circuits205(1)-205(12), each coupled through a contactor215(1)-215(12) to one of six batteries220(1)-220(6) and arranged to supply power to two or more propulsion systems105that are balanced about CG130(seeFIGS.1A,1B), as described in more detail below. More specifically, in this particular embodiment there are six primary isolated power distribution circuits205(1)-205(6) and six redundant isolated power distribution circuits205(7)-205(12). Each power distribution circuit205supplies power to a balanced pair of propulsion systems.

For example, primary power distribution circuit205(1) is coupled to battery1220(1) through contactor215(1) and supplies power to balanced propulsion systems105(1) and105(12). As shown inFIGS.1A and1B, propulsion systems105(1) and105(12) are balanced about CG130(seeFIGS.1A,1B) because propulsion system105(1) is the same distance along left wing125(e.g., +Y-axis) from CG130that propulsion system105(12) is along right wing120from the CG, providing a balanced moment Mx about the X-axis. Further, propulsion system105(1) is a same distance forward (along +X-axis) of CG130that propulsion system105(12) is aft (along −X-axis) of the CG, providing a balanced moment My about the Y-axis. The balanced propulsion systems can also be called “diametrically opposed” with respect to CG130. Thus, if battery220(1) supplies increased or decreased power to power distribution circuit205(1), aircraft100as shown inFIG.1Awill only raise or lower (e.g., change of force along Z-axis), but will not rotate about the X, Y or Z axes (in the flight configuration shown inFIG.1).

In this particular embodiment each propulsion system105includes a primary controller225(1)-225(12) coupled to a primary winding230(1)-230(12) and a redundant controller235(1)-235(12) coupled to a redundant winding240(1)-240(12). Primary winding230(1)-230(12) and redundant winding240(1)-240(12) each couple power to a respective shaft245(1)-245(12) that rotates a respective propeller250(1)-250(12). Primary controller225and primary winding230are electrically isolated from redundant controller235and redundant winding240such that if one controller or winding fails, shaft245still receives ½ power from the other controller and winding.

For example, propulsion system105(1) receives ½ power from battery220(1) through primary power distribution circuit205(1) that is coupled to primary controller225(1) and primary winding230(1) and receives ½ power from battery220(6) through redundant power distribution circuit205(12) that is coupled to redundant controller235(1) and redundant winding240(1). Thus, if battery220(1) fails, propulsion system105(1) still receives ½ power from battery6220(6). Since propulsion systems105(1) and105(12) are balanced, the power to each propulsion system is the same. In some embodiments a control or computing system255is used and can compensate and boost power supplied from battery6220(6) to propulsion systems105(1) and105(12) to compensate for the loss of ½ power due to a failure of battery1220(1).

In a like manner, battery2220(2) supplies power to propulsion systems105(2) and105(11) through primary power distribution circuit205(2); battery3220(3) supplies power to propulsion systems105(3) and105(10) through primary power distribution circuit205(3); battery4220(4) supplies power to propulsion systems105(4) and105(9) through primary power distribution circuit205(4), battery5220(5) supplies power to propulsion systems105(5) and105(8) through primary power distribution circuit205(5) and battery6220(6) supplies power to propulsion systems105(6) and105(7) through primary power distribution circuit205(6).

In this embodiment there are also six redundant power distribution circuits205(7)-205(12). Battery1220(1) supplies power to propulsion systems105(6) and105(7) through redundant power distribution circuit205(7); battery2220(2) supplies power to propulsion systems105(5) and105(8) through redundant power distribution circuit205(8); battery3220(3) supplies power to propulsion systems105(4) and105(9) through redundant power distribution circuit205(9); battery4220(4) supplies power to propulsion systems105(3) and105(10) through redundant power distribution circuit205(10); battery5220(5) supplies power to propulsion systems105(2) and105(11) through redundant power distribution circuit205(5); battery6220(6) supplies power to propulsion systems105(1) and105(12) through redundant power distribution circuit205(6). As appreciated by one of skill having the benefit of this disclosure other arrangements of primary and redundant power distribution circuits and propulsion systems are within the scope of this disclosure.

As shown inFIG.2, each primary and redundant power distribution circuit205is coupled to a respective battery220via a respective contactor215(1)-215(12). That is, each contactor215controls power supplied to a balanced pair of propulsion systems105via a respective power distribution circuit205. In some embodiments each contactor215is an electromechanical relay while in other embodiments it can be a different device, including but not limited to one or more solid-state switches. In various embodiments contactor215can be controlled with a current sensing circuit that senses a current flowing into or out of the respective battery220. When the current reaches a predetermined threshold, contactor215can open, breaking the connection between the battery220and the respective power distribution circuit205. Each power distribution circuit205shown inFIG.2by a single line is representative of a DC circuit that includes at least a power and a ground conductor. In some embodiments a common ground conductor can be used for two or more power distribution circuits205. In various embodiments contactors215can be positioned between only the positive or the ground conductor and battery220while in other embodiments they can be positioned between both the power and the ground conductors. In further embodiments fuses can be used in place of contactors215or in addition to contactors.

In some embodiments control system255can be coupled to controllers225,235, contactors215and/or batteries220to control one or more functions of power distribution system200, as described in more detail below. In one embodiment, control system255can make adjustments in one or more controllers225,235to maintain batteries220at a similar charge state. More specifically, in some embodiments one or more batteries220may be aged (e.g., older or having experienced more discharge cycles) and have a reduced charge capacity and/or one or more batteries may be swapped for a freshly charged battery such that batteries have an unequal charge state. Control system255can receive information from each battery220related to its charge state and adjust power drawn from each battery by adjusting an operation of one or more controllers225,235.

In some embodiments each controller225,235includes an inverter that receives DC power from power distribution circuit205and converts it to AC power that is supplied to motor windings230,240in terms of torque, rpm, blade pitch angle, etc. In various embodiments each propulsion system105includes an AC motor, however in other embodiments it can include multiple motors coupled to a single shaft and in further embodiments can be a DC motor. In some embodiments, such as shown inFIGS.1A and1B, aircraft100is over-actuated, that is it has more propulsion systems105(e.g., 12) than degrees of freedom (e.g., 6) and therefore control system255can adjust myriad combinations of controllers225,235to discharge a particular battery220faster or slower than others to maintain an equal charge state among all of the batteries. Thus, control system255can use forces and moments (e.g., Fx, Fy, Fz, Mx, My, Mz) and charge state of batteries220as inputs and can output commands to controllers225,235to optimize charge state, and power usage.

In some embodiments the balanced arrangement of the propulsion systems105on aircraft100enables even discharge of batteries220during cross-winds and other conditions. For example, as shown inFIG.1Aa cross-wind approaching from the left (e.g., from propulsion systems105(1),105(7) towards propulsion systems105(6),105(12) causes power draw from propulsion systems105(1) and105(7) to reduce and power draw from propulsion systems105(6) and105(12) to increase. However, as shown inFIG.2, propulsion systems105(1) and105(12) are coupled to the same batteries (e.g., batteries220(1) and220(6)) thus the increased power draw of105(12) offsets the decreased power draw of105(1), thus batteries220(1) and220(6) maintain a relatively similar rate of discharge as batteries220(2)-220(5). Similarly, propulsion systems105(6) and105(7) are balanced.

In some embodiments one or more diodes can be coupled in-series with power distribution circuits such that current can only flow out of batteries and not into batteries to protect the power distribution system in case of a shorted battery. In other embodiments power distribution system enables regenerative charging in which propulsion systems generate energy (e.g., during descent) and transfer power to batteries.

FIGS.3-6illustrate the operation of power distribution system200in the event of example failure modes. Other failure modes and responses to failure modes by power distribution system, although not shown, are within the scope of this disclosure.FIG.3illustrates the power distribution system200shown inFIG.2, however inFIG.3battery220(1) is shown as failed. As shown inFIG.3, failed battery220(1) causes contactor215(1) and contactor215(7) to open such that power is no longer supplied to propulsion system105(1) via primary controller225(1), to propulsion system105(12) via primary controller225(12) to propulsion system105(6) via redundant controller235(6) and to propulsion system105(7) via redundant controller235(7). Thus, propulsion systems105(1),105(6),105(7) and105(12) receive ½ the power that they were receiving before battery220(1) failure.

As described above, in some embodiments control system255can detect the failure, open contactors215(1),215(7) and immediately increase power to propulsion systems105(1),105(6),105(7) and105(12) from battery220(6) to restore 100% power to the aircraft. Alternatively, because of the balanced nature of the power distribution circuits205, control system255can increase power to propulsion systems105(1) and105(12) to compensate for the entire power loss from battery220(1), or could alternatively increase power to propulsion systems105(6) and105(7). Alternatively, control system255could take more complex action and increase power from battery220(2) to propulsion systems105(2) and105(11), for example, to compensate for the failure. One of skill in the art having the benefit of this disclosure will appreciate the many different options controller can use to compensate for the loss of battery220(1).

FIG.4illustrates power distribution system200shown inFIG.2, however inFIG.4battery contactor215(1) has failed and/or there is a short within power distribution circuit205(1). As shown inFIG.3, contactor215(1) can be opened once the failure is detected which cuts off power from power distribution circuit205(1) which supplies power to balanced propulsion systems105(1) and105(12). Thus power is reduced to aircraft100in a balanced matter. Because contactor215(1) breaks the connection between the failure and battery220(1), the battery can still supply power to power distribution circuit205(7) and propulsion systems105(6) and105(7) via contactor215(7).

FIG.5illustrates power distribution system200shown inFIG.2, however inFIG.5primary controller225(1) and/or primary winding230(1) has failed. As shown inFIG.5, contactor215(1) can be opened once the failure is detected which cuts off power from power distribution circuit205(1) and from battery220(1) to primary controller225(1) and primary winding230(1). Propulsion system105(1) can still receive ½ power from battery220(6) via redundant power distribution circuit205(12).

FIG.6illustrates power distribution system200shown inFIG.2, however inFIG.6shaft245(1) of first propulsion system105(1) is seized. As shown inFIG.6, contactor215(1) can be opened once the failure is detected which cuts off power from power distribution circuit205(1) and from battery220(1). Similarly, contactor215(12) can be opened which cuts off power from redundant power distribution circuit205(12) and from battery220(6). Because of the balanced arrangement, opening contactors215(1),215(12) also results in a complete loss of power delivered to propulsion system105(12). Because the loss of power to propulsion systems105(1) and105(12) is balanced, aircraft100will not rotate in response to the failure and will only lose altitude or speed. Control system255can compensate for the failure in myriad ways, as described above.

FIG.7illustrates a power distribution system700that is similar to power distribution system200shown inFIG.2, however inFIG.7the redundant power distribution circuits205(7)-205(12) have been removed. As shown inFIG.7each propulsion system705(1)-705(12) has only a primary controller225and a primary winding230. The primary power distribution circuits205(1)-205(6) still supply power to propulsion systems105in a balanced matter. However, if a primary power distribution circuit205(1)-205(6) fails there is no redundant power distribution circuit to continue to supply power to propulsion systems705. For example, if battery220(1) fails, contactor215(1) opens and balanced propulsion systems705(1) and705(12) cease operation. Control system255can compensate by increasing power from battery220(6) to balanced propulsion systems705(6) and705(7) or by taking myriad other actions.

FIG.8illustrates a power distribution system800that is similar to power distribution system200shown inFIG.2, however inFIG.8each primary power distribution circuit205(1)-205(6) and each redundant power distribution circuit205(7)-205(12) has been coupled together with a fuse805(1)-805(10). As shown inFIG.8first fuse805(1) couples first and second primary power distribution circuits,205(1),205(2), respectively, second fuse805(2) couples second and third primary power distribution circuits205(2),205(3), respectively, and similar connections are made for third fuse through fifth fuse,805(3)-805(5), respectively. Similarly, redundant power distribution circuits205(7)-205(12) are coupled together with sixth fuse805(6) that couples first and second redundant power distribution circuits205(7),205(8), respectively, seventh fuse805(7) that couples second and third redundant power distribution circuits205(8),205(9), respectively, and similar connections are made for eighth fuse through tenth fuse,805(8)-805(10), respectively.

Fuses805result in all power distribution circuits205having a common voltage level as they are all electrically coupled together. This arrangement enables the even discharge of batteries220and power sharing along the common bus. In the event of a shorted battery failure, e.g., battery220(2), first fuse805(1), second fuse805(2), sixth fuse805(6) and seventh fuse805(7) blow, isolating first battery220(1) from batteries220(3)-220(6). Essentially, a failure causes the failed power distribution circuits to “island” as a result of the fuses on either side of the failure blowing. In some embodiments contactors can be included, as shown inFIG.2to decouple each battery from primary and/or redundant power distribution circuits.

FIG.9illustrates a power distribution system900that is similar to power distribution system800shown inFIG.8and power distribution system200shown inFIG.2, however inFIG.9the redundant power distribution circuits205(7)-205(12) have been removed. As shown inFIG.9each propulsion system905has only a primary controller225and a primary winding230. Primary power distribution circuits205(1)-205(6) are each coupled together via fuses805(1)-805(5) to form a common bus and supply power to propulsion systems905in a balanced matter. Fuses805result in all power distribution circuits205having a common voltage level as they are all electrically coupled together. This arrangement enables the even discharge of batteries220and power sharing along the common bus. Similar toFIG.8, in the event of a failure, the failed power distribution circuits and/or battery is “islanded” through the blowing of one or more fuses on either side of the failure. In some embodiments contactors can be included, as shown inFIG.2to decouple each battery from primary and/or redundant power distribution circuits.

Although aircraft100(seeFIG.1) is described and illustrated as one particular configuration of aircraft, embodiments of the disclosure are suitable for use with a multiplicity of aircraft. For example, any aircraft that uses two or more electronic propulsion systems can be used with embodiments of the disclosure. In some instances, embodiments of the disclosure are particularly well suited for use with aircraft that carry one or more persons because of the need for reliability, however the power distribution system disclosed herein is not limited to “manned” aircraft and can be used on any aircraft “manned” and “unmanned” of any size.

For simplicity, various electrical components, such as capacitors, current sense circuits, controller details, processors communications busses, memory, storage devices and other components of the power distribution system are not shown in the figures.

In the foregoing specification, embodiments of the disclosure have been described with reference to numerous specific details that can vary from implementation to implementation. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the disclosure, and what is intended by the applicants to be the scope of the disclosure, is the literal and equivalent scope of the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. The specific details of particular embodiments can be combined in any suitable manner without departing from the spirit and scope of embodiments of the disclosure.

Additionally, spatially relative terms, such as “bottom or “top” and the like can be used to describe an element and/or feature's relationship to another element(s) and/or feature(s) as, for example, illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and/or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as a “bottom” surface can then be oriented “above” other elements or features. The device can be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

With reference to the appended figures, components that can include memory (e.g., control or computing system255, controllers225,235, etc.) can include non-transitory machine-readable media. The terms “machine-readable medium” and “computer-readable medium” as used herein refer to any storage medium that participates in providing data that causes a machine to operate in a specific fashion. In embodiments provided hereinabove, various machine-readable media might be involved in providing instructions/code to processors and/or other device(s) for execution. Additionally or alternatively, the machine-readable media might be used to store and/or carry such instructions/code. In many implementations, a computer-readable medium is a physical and/or tangible storage medium. Such a medium may take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Common forms of computer-readable media include, for example, magnetic and/or optical media, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read instructions and/or code.

The methods, systems, and devices discussed herein are examples. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For instance, features described with respect to certain embodiments may be combined in various other embodiments. Different aspects and elements of the embodiments may be combined in a similar manner. The various components of the figures provided herein can be embodied in hardware and/or software. Also, technology evolves and, thus, many of the elements are examples that do not limit the scope of the disclosure to those specific examples.

It has proven convenient at times, principally for reasons of common usage, to refer to such signals as bits, information, values, elements, symbols, characters, variables, terms, numbers, numerals, or the like. It should be understood, however, that all of these or similar terms are to be associated with appropriate physical quantities and are merely convenient labels. Unless specifically stated otherwise, as is apparent from the discussion above, it is appreciated that throughout this specification discussions utilizing terms such as “processing,” “computing,” “calculating,” “determining,” “ascertaining,” “identifying,” “associating,” “measuring,” “performing,” or the like refer to actions or processes of a specific apparatus, such as a special purpose computer, controller, or a similar special purpose electronic computing device. In the context of this specification, therefore, a special purpose computer or a similar special purpose electronic computing device is capable of manipulating or transforming signals, typically represented as physical electronic, electrical, or magnetic quantities within memories, registers, or other information storage devices, transmission devices, or display devices of the special purpose computer or similar special purpose electronic computing device.

Those of skill in the art will appreciate that information and signals used to communicate the messages described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Terms “and,” “or,” and “an/or,” as used herein, may include a variety of meanings that also is expected to depend at least in part upon the context in which such terms are used. Typically, “or” if used to associate a list, such as A, B, or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B, or C, here used in the exclusive sense. In addition, the term “one or more” as used herein may be used to describe any feature, structure, or characteristic in the singular or may be used to describe some combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example and claimed subject matter is not limited to this example. Furthermore, the term “at least one of” if used to associate a list, such as A, B, or C, can be interpreted to mean any combination of A, B, and/or C, such as A, B, C, AB, AC, BC, AA, AAB, ABC, AABBCCC, etc.

Reference throughout this specification to “one example,” “an example,” “certain examples,” or “exemplary implementation” means that a particular feature, structure, or characteristic described in connection with the feature and/or example may be included in at least one feature and/or example of claimed subject matter. Thus, the appearances of the phrase “in one example,” “an example,” “in certain examples,” “in certain implementations,” or other like phrases in various places throughout this specification are not necessarily all referring to the same feature, example, and/or limitation. Furthermore, the particular features, structures, or characteristics may be combined in one or more examples and/or features.

In the preceding detailed description, numerous specific details have been set forth to provide a thorough understanding of claimed subject matter. However, it will be understood by those skilled in the art that claimed subject matter may be practiced without these specific details. In other instances, methods and apparatuses that would be known by one of ordinary skill have not been described in detail so as not to obscure claimed subject matter. Therefore, it is intended that claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter may also include all aspects falling within the scope of appended claims, and equivalents thereof.

For an implementation involving firmware and/or software, the methodologies may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. Any machine-readable medium tangibly embodying instructions may be used in implementing the methodologies described herein. For example, software codes may be stored in a memory and executed by a processor unit. Memory may be implemented within the processor unit or external to the processor unit. As used herein the term “memory” refers to any type of long term, short term, volatile, nonvolatile, or other memory and is not to be limited to any particular type of memory or number of memories, or type of media upon which memory is stored.

If implemented in firmware and/or software, the functions may be stored as one or more instructions or code on a computer-readable storage medium. Examples include computer-readable media encoded with a data structure and computer-readable media encoded with a computer program. Computer-readable media includes physical computer storage media. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, compact disc read-only memory (CD-ROM) or other optical disk storage, magnetic disk storage, semiconductor storage, or other storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer; disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

In addition to storage on computer-readable storage medium, instructions and/or data may be provided as signals on transmission media included in a communication apparatus. For example, a communication apparatus may include a transceiver having signals indicative of instructions and data. The instructions and data are configured to cause one or more processors to implement the functions outlined in the claims. That is, the communication apparatus includes transmission media with signals indicative of information to perform disclosed functions. At a first time, the transmission media included in the communication apparatus may include a first portion of the information to perform the disclosed functions, while at a second time the transmission media included in the communication apparatus may include a second portion of the information to perform the disclosed functions.