Abstract:
The instantaneous power consumption of an appliance is used to determine the status of the appliance, from which further actions may be taken. This invention is premised on the observation that most appliances have a characteristic power consumption pattern that can be used to determine the state of operation of the appliance. An electric coffee pot, for example, consumes high power substantially continuously during the brewing state, then reduces its power level, or power duration, or both, while keeping the pot warm, then terminates its power consumption when it is turned off. In like manner, the power consumption patterns of other appliances, such as toasters, washing machines, dryers, and so on may also be used to determine the state of each appliance. The communicated state may be used by a home-automation system to effect a variety of actions, including notifying the user, terminating the available power to the appliance, initiating an action by another appliance, and so on.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of consumer devices, and in particular to the field of automated home control systems. 
     2. Description of Related Art 
     Home automation is becoming increasingly popular. Standards continue to be developed which will allow devices of varying types and varying vendors to be controlled by a common controller. Such standards include IEEE 1394, X-10, HAVi, HomeAPI, Jini, and the like. IEEE 1394 and X-10 are communication protocols; HAVi is a software architecture using IEEE 1394; Home API is an open industry specification that defines a standard set of software services and application programming interfaces which enable software applications to monitor and control home device. Jini is a distributed software architecture (network) wherein clients see devices and services as objects. 
     Some home automation systems may include a monitoring and reporting system that maintains a record of selected events. For example, U.S. Pat. No. 4,644,320, “HOME ENERGY MONITORING AND CONTROL SYSTEM”, issued Feb. 17, 1987 for Carr et al, incorporated by reference herein, presents a system that periodically records the temperature inside and outside the home, and a cumulative energy usage, measured via energy measuring devices that are attached to appliances such as furnaces, air conditioners, and the like. Statistics are also provided and presented as text or graphic displays to facilitate a user&#39;s assessment of the energy usage, and potentially effect a change of habit to reduce such usage. 
     Typical home automation systems are configured to provide a central control station and a number of remote controllers. For example, the central control station may be a home computer, and the remote controllers may be sub-controllers located in particular areas of the home, such as in a master bedroom, entry foyer, and the like. Typical home automation systems may also include remote sensors that are used, for example, to automatically turn lights on or off when motion is detected, or to turn a television set on or off in response to a particular sound or voice command. Some home automation systems allow the desired operations to be preprogrammed, so that, for example, lights or appliances are turned on or off at different preset times, televisions are tuned to different channels at different times, and so on. 
     As detailed above, most home automation systems are fundamentally “unidirectional”: information flows from the user to the appliance. The user provides commands to appliances, either directly or indirectly, and the appliance is controlled to effect the command. Some appliances are available that contain a degree of “intelligence” to effect a “bidirectional” information flow by communicating information to the user regarding their status, available options, and so on. Such a bidirectional information flow capability, however, is typically available only from fairly sophisticated appliances, such as home-entertainment systems, wherein the additional cost associated with providing the “intelligence” required is insubstantial, or deemed to be worthwhile to effect a product differentiation. Also, even if a majority of future appliances contain sufficient intelligence to communicate their status to a home automation system, the cost of replacing every legacy appliance in one&#39;s home to obtain such intelligent appliances will be cost-prohibitive to most users. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of this inventing to provide a method for communicating a status of an appliance that is easy to implement regardless of the capabilities of the appliance. It is a further object of this invention to provide a method for communicating a status of an appliance without requiring a modification to the appliance. It is a further object of this invention to provide an appliance-independent device that can provide status information that can be used to determine the status of its associated appliance. It is a further object of this invention to provide a method and device to enhance the physical security of the appliances in a home-automation system. 
     These objects and others are achieved by monitoring the instantaneous power consumption of an appliance to determine the status of the appliance. This invention is premised on the observation that most appliances have a characteristic power consumption pattern that can be used to determine the state of operation of the appliance. An electric coffee pot, for example, consumes high power substantially continuously during the brewing state, then reduces its power level, or power duration, or both, while keeping the pot warm, then terminates its power consumption when it is turned off. Additionally, distinctive power consumption patterns may be associated with, for example, the repeated heating of an empty or near empty coffee pot, the absence of the coffee pot, and so on. In like manner, the power consumption patterns of other appliances, such as toasters, washing machines, dryers, and so on may also be used to determine the state of each appliance. The communicated state may be used by the home-automation system to effect a variety of actions, including notifying the user, terminating the available power to the appliance, initiating an action by another appliance, and so on. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in further detail, and by way of example, with reference to the accompanying drawings wherein: 
         FIG. 1  illustrates an example block diagram of a home-automation system in accordance with this invention. 
         FIG. 2  illustrates an example block diagram of a power monitoring device in accordance with this invention. 
         FIG. 3  illustrates an example timing diagram that is characteristic of the current drawn by an example coffee maker appliance. 
         FIG. 4  illustrates an example state diagram that is characteristic of an example coffee maker appliance. 
         FIG. 5  illustrates an example timing diagram that is characteristic of the current drawn by an example washing machine appliance. 
         FIG. 6  illustrates example characteristic patterns associated with states of an example washing machine appliance. 
         FIG. 7  illustrates an example flow diagram for a processing device in accordance with this invention. 
       Throughout the drawings, same reference numerals indicate similar or corresponding features or functions. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates an example block diagram of a home-automation system  100  in accordance with this invention. The home-automation system  100  includes a variety of appliances  110 ,  120 ,  130 ,  140 , and  160  and ancillary devices  115 ,  125 ,  135 ,  145 ,  150 , and  170  that facilitate the communication and processing of information and commands related to the appliances  110 ,  120 ,  130 ,  140 , and  160  or other systems within a home. For ease of understanding, an appliance is defined herein as a device that has a primary function, such as making coffee, washing clothes, providing entertainment, and the like, that is substantially independent of providing automation information and control. 
     In accordance with this invention, at least one appliance  110  includes a power monitor device  115  that provides a measure  116  of the power  111  consumed by the appliance  110  to a processing device  150 . Based on a sequence of these measures  116 , the processing device  150  determines a state of the appliance  110 . The processing device  150  also initiates actions based on the determined state of the appliance  10 . For example, the processing device  150  may provide a notification signal to the annunciator  170  to notify a user when the coffee maker appliance  110  reaches a “finished brewing” state. Similarly, the processing device  150  may provide a control signal to turn off the coffee maker appliance  110  when the coffee maker appliance  110  reaches a “warming an empty pot” state. Alternatively, the processing device  150  may receive the state  146  of an appliance  140  directly, via a status reporter  145 , and effect operations based on a mix of power measures  116  and status reports  146 . For example, if the clock-radio appliance  140  reports a “snooze” state  146 , the processing device  150  turns on the coffee maker appliance  110 , then communicates a command to the clock-radio appliance  140  to terminate the “snooze” state  146  and turn the radio on when the coffee maker appliance  110  reports a “finished brewing” state. 
       FIG. 2  illustrates an example block diagram of a power monitor device  200  that may be used as the power monitor devices  115 ,  125 ,  135  in  FIG. 1 , and, in an alternative embodiment, the status reporter devices  145 ,  165 . In a preferred embodiment, the power monitor device  200  includes a current monitor  210  for measuring the current being drawn by the appliance (not shown), and a communications device  220  for communicating the measure of the current to a processing device, which is typically remote from the power monitor device  200 . The power monitor device  200  is illustrated as having a plug  201  for connection to a line supply  101 , and a socket  211  for providing power to the appliance, although the socket  211  would not be required when the power monitor  200  is embodied in the appliance, as illustrated in  FIG. 1  as power monitor  135  in the oven appliance  130 . As illustrated, the power monitor  200  also includes an optional control device  290  for disconnecting the supplied power from the socket  211 . 
     The current monitor  210  utilizes conventional current detection techniques to provide a measure of the current. The current may be detected directly, via an in-line sensor or shunt device, or indirectly, via, for example, an induction coil in proximity to the wire that provides the power to the appliance. The form of the current measure will depend upon the degree of resolution desired or required for determining the state of an appliance. For example, two bits of resolution can be used to signifying one of four possible states: no current flow; minimal current flow; nominal current flow; and high current flow. By providing an indication of multiple power levels appliances may be configured to draw a small but detectable amount of current when turned off and plugged into the monitor  210 , so that an “absent” state can be distinguished from an “off” state. In this manner, the monitor  210  may also serve as a security device that alerts the user, or other party, of the removal of a monitored appliance. The particular delineation points among the current measures are fairly arbitrary; in a preferred embodiment, no current flow is less than 0.001 amps, minimal current flow is between 0.001 and 0.1 amps; nominal between 0.1 and 1 amp, and high is above 1 amp. Alternatively, an eight or sixteen bit number may be communicated representing, for example, a measure of the current in milliamps, or, at the other extreme, a single bit may be communicated indicating whether any measurable amount of current is being drawn. These and other techniques for measuring current flow, or power consumption, will be evident to one of ordinary skill in the art. 
     The communications device  220  communicates the current measure to a processing device that is typically remote from the power monitor device  200 . Any number of conventional techniques may be employed to effect this communication, such as via an RF transmission, via a wired connection such as an IEEE RS-232 or IEEE 1394 direct connection, or, in a preferred embodiment, via a communications technique that utilizes the AC supply lines  101  to effect the communications, such as an X-10 compatible device, common in the art of home-automation. 
     Optionally, the power monitor  200  may include a processing device  250  that effects a similar function as the processing device.  150 , and an annunciator  270  that effects a similar function to the annunciator  170 . That is, in accordance with this invention, the processing device that determines an appliance&#39;s state based on the power measurement may be local  250  to the appliance, or remote  150  from the appliance, and, the annunciator that notifies a user of the status, or change of status, of the appliance, may also be local  270  or remote  170 . As illustrated, the optional processing device  250  may communicate the state of the appliance or other messages to the communicator  220 , for communication with other devices, such as a remote annunciator  170 , or the remote processing device  150 . 
     For ease of reference, the invention will be discussed hereinafter with regard to remote devices  150 ,  170 ; the application of the principles presented to the local devices  250 ,  270  will be evident to one of ordinary skill in the art. 
     The processing device  150  determines the state of the appliance based on the reported power measurements. In general, the state of the appliance is determined via a sequence of reported power measurements, by comparing the sequence with a set of predetermined sequences corresponding to each state, or each state transition. Any of a variety of techniques, common in the art, may be used to determine a state of an appliance.  FIG. 3  illustrates a timing diagram and  FIG. 4  illustrates a state diagram for an example coffee maker appliance  110 .  FIG. 5  illustrates a timing diagram and  FIG. 6  illustrates a pattern characterization for an example washing machine appliance  120 . Note that the timing diagram patterns are presented for illustrative purposes; specific appliances will exhibit similar or different characteristic patterns. 
     Line  3 A of  FIG. 3  illustrates an example characteristic pattern of the current drawn by the coffee maker appliance  110  during a typical usage. During the brewing stage, the appliance  110  draws continuous current  310  until a thermostat or other device in the appliance  110  signals the end of the brewing stage and terminates the current draw, at  311 . After some period of time, a thermostat signals a decrease in temperature at the warming plate that holds the coffee pot, and current  312  is again drawn, to keep the coffee warm, then terminated  313 , then drawn  314 , and so on, in a typical thermostatically controlled cyclic warming process. If an empty, or near empty, coffee pot is on the warming plate, the duration of the thermostatic cycle will decrease, because there is less coffee to heat, and thus less energy is required to raise the temperature of the coffee pot, as illustrated by the shorter current drawing segments  320 ,  322 ,  324  of  FIG. 3 , and corresponding shorter cooling segments  321 ,  323 . 
     Line  3 B of  FIG. 3  illustrates a power measurement sampling of the current consumption pattern of Line  3 A. In this example, the power measure is a simple on/off measure. The “on” or “drawing current” condition is illustrated in Line  3 B as an up-arrow, and the “off” or “insubstantial current” condition is illustrated as the absence of the up-arrow. This representation may correspond, for example, to a system in which, to conserve energy, a power measure is communicated only when power is being drawn by the appliance. As illustrated, the power monitor provides a sequence  360 - 374  of power measures corresponding to the current drawing pattern  310 - 324  of the coffee maker appliance  110 . 
       FIG. 4  illustrates an example state diagram  400  for determining a state of the coffee maker appliance  110  based on a sequence of power measures, starting from an initial “off” state  410 . The state diagram  400  is an alternative view of the characteristic pattern associated with the operation of a coffee make appliance  110  during typical usage. The example sequence  360 - 374  is used to demonstrate the operation of the state diagram  400 . When the first “on”, or “1” power measure  360  is received, the processing device  150  determines that the appliance  110  has entered a brew state  420 . The appliance  110  remains in this state  420  until a thermostat or other device in the appliance  110  terminates the current draw, at  311  of FIG.  3 . This is signaled by a “off”, or “0” power measure  361 , that effects a transition to a first “warm” state, warm 0  state  430  in FIG.  4 . Upon receipt of the next “1” power measure  362 , the state is changed from the warm 0  state  430  to a second “warm” state; warm 1   440 ; however, if a “1” power measure is not received within a time duration T off    390 , the state is changed  435  from warm 0  state  430  to the “off” state  410 . 
     In the example presented, a properly operating coffee maker appliance  110  will draw current  312  for at least a time duration T short    392  during the warming stage. A reported “off” state  363  after the time duration T short    392  effects a transition from warm 1  state  440  back to the warm 0  state  430 . The transition from warm 0   430 , to warm 1   440 , and back to warm 0   430  continues throughout the routine thermostatically controlled warming cycle discussed above. However, if an empty coffee pot is being heated, a short current drawing period  320  results. As illustrated in  FIG. 4 , if the power measure is reported to be “off”  371  before a time duration T short    392  from the “on” measure  370  that effected the transition into the warm 1   440  state, the state is changed from the warm 1   440  state to a “problem” state  450 . That is, if an empty coffee pot is being heated, the processing device  150  determines a “problem” state  450 , based on the reported power measures  370 - 371  corresponding to the above discussed shortened current draw  320 . In like manner, similar to the time duration T shor    392 , a time duration T long    391  is defined, such that a continued current draw, indicated by a continued “on” power measure  445  in the warm  1440  state also effects a transition to the “problem” state  450 . 
     Thus, as shown, an information processor  150  of the example system of  FIG. 1  can determine when a coffee maker appliance  110  is off, brewing, warming, or exhibiting a problem, based on the sequence of binary power measures  116  ( 360 - 374 ) received from a power monitor  115  associated with the coffee maker appliance  110 . In a preferred embodiment of this invention, the information processor  150  effects an action in response to particular states, or state transitions. When the information processor  150  determines that the coffee maker appliance  110  has left the “brew” state  420 , it notifies the user that the coffee is ready for consumption. This notification can be effected in a variety of ways, including a spoken message or particular tone sequence via the annunciator  170 , or local annunciator  270 , a recorded or generated audio or video message via the television  160 , and so on. Copending U.S. patent application Ser. No. 09/165,682 filed Oct. 2, 1998 for Eugene Shteyn for CONTROL PROPERTY IS MAPPED ONTO MODALLY COMPATIBLE GUI ELEMENT, presents a method of mapping messaging onto any object oriented system, such as a home networking system, and is incorporated by reference herein. In a preferred embodiment, the messaging is not necessarily limited to notifications, and may include other effected actions by the information processor  150 . For example, when the processing device  150  determines that the coffee maker appliance  110  is in the “problem” state, it communicates a control signal to shut off the appliance  110 , using, for example, an optional control device  290  in the power monitor  115  ( 200 ), and resets  401  the state diagram  400  of  FIG. 4  to the “off” state  410 . In like manner, when the processing device  150  determines that the coffee maker appliance  110  has completed the “brew” state, it may communicates a control signal to turn on other appliances, such as the clock radio  140 . 
       FIG. 5  illustrates a example timing diagram for a washing machine appliance  120 .  FIG. 5  is similar to  FIG. 3 , except that the power measures  560 - 576  illustrated in Line  5 B are of varying amplitudes, indicating a higher resolution of measure than the binary measures  360 - 374  of FIG.  3 . For example, the current draw  516  for a spin cycle is illustrated on Line  5 A as a decreasing function, corresponding to decreasing energy being required to spin the clothing as their water content decreases. Correspondingly, the reported power measure  567  at the end of the spin cycle is illustrated as being less than the power measure  566  at the beginning of the spin cycle. Also note that the reported power measure  567  at the end of the spin cycle is illustrated as being less than the power measure  563  at the end of the wash cycle. In a preferred embodiment of this invention, the processing device  150  utilizes the additional resolution of the provided power measure to distinguish the states of the example washing machine appliance  120 . 
       FIG. 6  illustrates five example characteristic timing diagrams, or patterns  6 A- 6 E, for determining the commencement of each of five states: wash, 1 st  spin, rinse, 2 nd  spin, and finished. Although a conventional state analysis, similar to  FIG. 4 , may be used to determine the state of the washing machine appliance  120 ,  FIG. 6  is presented as an example alternative method for distinguishing the states of an appliance. Illustrated in pattern  6 A, the beginning of the wash state is characterized by an extended “off” period  660 , followed by a current draw  662 , corresponding to the power measures  560 ,  562  illustrated on Line  5 B of FIG.  5 . Pattern  6 B represents the commencement of the 1 st  spin state, and is characterized by a substantial current draw  663  followed by little or no current draw for a duration  664 , followed by a current draw  666 , corresponding to the power measures  563 ,  564 ,  566  of  FIG. 5 , respectively. As is common in the art of pattern recognition, transition periods  605  are ignored in the determination of states based on the amplitude of the reported power measures. 
     As illustrated in  FIG. 6 , pattern  6 B is very similar to patterns  6 C and  6 D . The processing device uses the reported power measure amplitudes  663 ,  667  to distinguish the characteristic pattern  6 B of the 1 st  spin state from the characteristic pattern  6 C of the rinse state. In a preferred embodiment, the rinse cycle is characterized as having a large ratio of reported power measure  670  to power measure  667 , while the ratio of reported power measure  666  to power measure  663  is relatively small, and is characteristic of the 1 st  spin cycle. 
     Measures other than the amplitude of the reported power measure are also used to distinguish states. For example, the 1 st  spin cycle pattern  6 B is distinguished from the 2 nd  spin cycle pattern  6 D by a substantially shorter period  664  of little or no current draw, compared to the period  672  of pattern  6 D, corresponding to the periods  514  and  522 , respectively, of FIG.  5 . In like manner, the finished state pattern  6 E is characterized by the absence of a subsequent current draw after an interval  676  from a prior current draw  675 . 
     As would be evident to one of ordinary skill in the art, the techniques discussed above for determining a state based on a sequence of power measures, and other techniques common in the art, can be combined as required to provide the desired level of distinction among states. Note also that the determination of state based on power measures facilitates the development of a monitoring and notification system that can be customized for each user. That is, the definition and determination of each state resides in the embodiment of the processing device  150 , rather than being predefined for each appliance. In accordance with this aspect of the invention, the integration of a variety of appliances into a home automation network  190  can be effected without requiring an agreed upon standard of definitions of states among the multitude of vendors that provide the various appliances, and without being constrained by a particular vendor&#39;s defined states for an appliance. 
     In accordance with another aspect of this invention, the rules and characteristics associated with determining a state of an appliance from a sequence of power measures may be provided by an external source, such as a vendor who provides this information as a means for product differentiation, or to increase the perceived value of the appliance. Copending U.S. patent applications Ser. No. 09/160,490 filed Aug. 25, 1998 for Adrian Turner et al., for CUSTOMIZED UPGRADING OF INTERNET-ENABLED DEVICES BASED ON USER-PROFILE, and U.S. Ser. No. 09/189,535 filed Nov. 10, 1998 for Eugene Shteyn for UPGRADING OF SYNERGETIC ASPECTS OF HOME NETWORKS, both incorporated by reference herein, present the upgrading of an appliance by downloading software representative of enhanced versions of the appliance, preferably via the Internet. Copending U.S. patent application Ser. No. 09/311,128 filed May 13, 1999 for Joost Kemink for INTERNET-BASED SERVICE FOR UPDATING A PROGRAMMABLE CONTROL DEVICE, incorporated by reference herein, presents the updating of a programmable control device to facilitate the control of the appliance, also via the Internet. Using techniques similar to those presented in these referenced applications, the processing device  150  can receive the information and programming required to effect the determination of states for selected appliances. 
       FIG. 7  illustrates an example flow diagram for a processing device  150  in accordance with this invention. At  710 , the state variable is initialized, typically to an “off” state. Each reported power measure is received, at  720 . For ease of reference,  FIG. 7  illustrates the processing of reports from a single appliance. In a preferred embodiment of this invention, the reported power measure will have an associated source address that is used to determine the appliance associated with the reported power measure. The reported power measure is processed to create a sequence of prior power measures  730 . As is common in the art, the processing of the measure may include scaling to provide a normalized measure that facilitates the subsequent comparison, at  740 , with the appliance characteristics. Other conversions may also be effected at the processing block  730 . For example, the power measure may be reported as an eight-bit number, while the appliance, such as the example coffee maker appliance  110 , may only require a one-bit binary value to determine its state. The length of the sequence is determined by the characteristics of the appliance. A simple on/off state determination, for example, only requires a sequence of one power measure, whereas the example washing machine appliance  120  discussed above requires a longer sequence, to distinguish, for example, between example characteristic patterns  6 B and  6 D in FIG.  6 . Note that, as is common in the art, any one of a variety of techniques may be used to assemble the sequence. For example, a time-since-last-change parameter may be utilized, rather than a sequence of repetitive measures, or, as is common in state table processing, a recording of the prior state and the new input measure is a sufficient representation of a sequence. 
     The processed sequence is compared to the characteristic  745  associated with the appliance, at  740 . As discussed above, the form of the characteristics  745  can be any of a variety of forms that facilitate a determination of the state of the appliance from the reported sequence. For example, the characteristics  745  of the coffee maker appliance  110  may be in the form of a state machine that effects the state transitions illustrated in FIG.  4 . Conversely, the characteristics  745  of the washing machine appliance  120  may be in the form of graphic patterns, and the comparison block  740  is configured as a pattern matching system. These and other forms of information processing techniques to facilitate comparisons will be evident to one of ordinary skill in the art in view of this disclosure. 
     If, at  750 , the comparison at  740  indicates a change of state, the state variable is updated, at  760 . At  770 , the appropriate action, if any, corresponding to this change of state is determined, and effected, typically by communicating a message to another device, such as the annunciator  170 , another appliance, such as the television appliance  160 , or to the appliance corresponding to the reported power measures, such as the coffee pot appliance  110 .  FIG. 7  illustrates a typical state-transition driven process, wherein actions are effected only when the appliance undergoes a change of state. As is evident to one of ordinary skill in the art, placing the block  770  outside the conditional path, for example, at  780 , will provide for effecting actions with every reported power measure. Alternatively, forming the block  770  as a process that is independent of the flow of  FIG. 7  will provide for a continuous determination of actions, and would be useful, for example, to detect an absence of the power monitor device. In a preferred embodiment, the actions are determined via a collection of rules  775  associated with the appliance. As with the characteristics  745 , the rules  775  may be any of a variety of forms. In a preferred embodiment, the rules are conventional IF-THEN-ELSE statements, common in the art of programming. For example, a rule for the coffee pot appliance  110  may be “IF new state=warm THEN send Message 1  to Annunciator 3 ”, where Message 1  is a recorded or generated message corresponding to the coffee being ready, and Annunciator 3  is an identification of one or more devices or appliances that are used to render the message to notify the user. After effecting whatever actions are required, the process continues, via the loop back to block  720  to receive the next power measure. 
     The foregoing merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are thus within its spirit and scope. For example, the system of  FIG. 1  is illustrated as having a single processing device  150 . Co-pending U.S. patent application Ser. No. 09/222,403 filed Dec. 29, 1998 for Doreen Cheng for HOME CONTROL SYSTEM WITH DISTRIBUTED, NETWORKED DEVICES, presents a distributed network of processing devices, and is incorporated by reference herein. 
     The particular configurations and structures are presented in the figures for illustration purposes. Alternative arrangements are feasible as well. For example, the processing device  150  is illustrated as being connected directly to the home network  190 . An alternative arrangement could include a processing device  150  that is remote from the home, such as a service provided by a security monitoring agency, that is connected via a telephone or cable network. In like manner, an annunciation device  170  may be located at a remote location, and used to provide security alert notifications when monitored appliances are reported as being absent, or when the monitor unexpectedly ceases transmission. These and other system configuration and optimization features will be evident to one of ordinary skill in the art in view of this disclosure, and are included within the scope of the following claims.