Description of The Preferred Embodiment
Fig. 1 illustrates, in block diagram form, an overview of a remote telemetry system 100 in accordance with one embodiment. It should be noted that although the present invention will be described with reference to electrical service, the principles of the present invention are equally applicable to other utility companies, such as water and gas service providers, and other industries that require remote monitoring, control and/or service of remote stations as previously discussed.
A plurality of remote metering units 102a-102n are each located at a base point throughout the utility network. For example, remote metering units 102a-102n may be located in residential and commercial buildings where end use of utility services occurs. The mobile units may also be located at key distribution points such as substations where larger scale monitoring is desired. The remote metering units 102a-102n may be comprised of, for example, a base transceiver coupled to an existing conventional electric machine utility meter through an interface device suitable for the type of metering (i.e., dial or odometer type). The advantage of this configuration is that small, low cost and easily manufactured devices can be easily adapted to be installed on existing meters without the need for expensive system upgrades. This remote metering unit is described below with reference to fig. 2.
In one embodiment, the remote metering units 102a-102n each perform basic measurement functions, including reporting utility service consumption, meter tampering detection and reporting, usage disruption reporting, and service level "surge" and "brownout" detection and reporting. The remote metering units 102a-102n may send their reported messages to the central controller 116 through at least one base station 108 and a Mobile Telephone Switching Office (MTSO)110, the MTSO 110 interfacing with a Public Switched Telephone Network (PSTN) 112. The central controller 116 may comprise, for example, a computer system and associated memory database and interface circuitry that allows application specific software for performing the control functions described herein. In various embodiments to be described below, various intermediate communication units or "hops" may be interposed in a "mesh network" fashion between the remote metering units 102a-102n and the central controller 116. The intermediate communication units include a subscriber mobile unit 140, a mobile base unit 130, a subscriber home computer 132, and a home base unit 122. Each of these various embodiments may coexist in the same large-scale system.
In one embodiment, base station 108 and MTSO 110 belong to a Code Division Multiple Access (CDMA) spread spectrum communication system. An example of such a SYSTEM is described in U.S. Pat. No. 4,901,307, published 2/13 1990, entitled "SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE TERRESTRIAL REPEATERS", assigned to the assignee of the present invention and incorporated herein by reference. Further, the wireless communication system may be designed in accordance with Telecommunication Industry Alliance (TIA)/Electronic Industry Alliance (EIA) temporary Standard 95 entitled "Mobile Station-Base Station compatibility Standard for Dual-Mode Wireless broadband Spectrum cellular System" or cdma2000 Standard for cdma2000 broadband Spectrum Systems ". Alternatively, wireless communication systems may be designed in accordance with ANSI J-STD-008 entitled "Personal Station-Base Station Compatibility Requirements for 1.8to 2.0GHz Code Division Multiple Access (CDMA) Personal communications systems". It should be noted, however, that the principles of the present invention are applicable to other wireless communication systems, whether cellular or non-cellular, and regardless of the modulation scheme employed. For example, the present invention IS equally applicable to Time Division Multiple Access (TDMA) based systems, such as the United states TDMA Standard IS-54, or the Global System for Mobile communications (GSM) throughout Europe. Furthermore, the principles of the present invention may be applied to modulated communication systems at analog frequencies, such as the Advanced Mobile Phone System (AMPS).
In one embodiment, the remote metering units 102a-102n send their respective reporting messages to the intermediate communication unit over the ad hoc network. Advantages of using ad hoc networks include flexibility in infrastructure architecture, lack of wired connections, and flexible network topology. Ad hoc networks enable intermediate communication units to be mobile and low power, which units can be carried by people or installed in cars. The intermediate communication unit interrupts the metering units 102a-102n for any data transfer without network planning. The ad-hoc network may, for example, be based on bluetooth, IEEE 802.11 or ultra wideband communication protocols.
The bluetooth communication protocol provides a simple and short range (e.g., 10 meters to 100 meters), wireless-based solution for robust data and voice transmission without the need for cables or in-line. It provides many advantages such as low complexity, low power consumption, low cost, frequency hopping and time division duplex implementations. Bluetooth devices coming within range of each other may dynamically set up ad-hoc point-to-point and/or point-to-multipoint wireless connections. The standard is applicable to battery powered devices. The bluetooth communication protocol is well known in the art.
The IEEE 802.11 communication protocol provides for connectivity between devices on an ad hoc basis in a Wireless Local Area Network (WLAN) environment. This wireless communication standard has a higher data rate, a longer range, e.g., up to 90, and higher power requirements. The standard is applicable to non-battery powered devices. The IEEE 802.11 communication protocol is well known in the art.
Ultra-wideband communication protocols also provide connectivity between devices on a particular basis. It provides a flexible, low-cost implementation for short-range direct communication without requiring any base stations. This particular communication protocol is also well known in the art.
In one embodiment, the mobile unit 140 may receive information from the metering unit 102n and transmit the received information to the base station 108 according to a scheduled data transfer scheme. When a mobile unit comes within range of the metering unit 102n, the mobile unit may receive information from the metering unit 102n over an ad hoc network. The mobile unit can also be carried by a person or a vehicle. The person carrying the mobile unit may be walking, jogging, cycling, or carrying an object in the vicinity of the metering unit 102 n. Vehicles carrying mobile units may include delivery trucks, passenger trains, buses, and/or taxis. When such a mobile unit, which is enabled by an ad-hoc network, comes within range of an ad-hoc network-enabled metering device, the mobile unit may read and save information from the metering device. However, the mobile unit transmits this information to another wireless device or a central controller either automatically or according to a planned data transfer scheme, which is managed by the wireless infrastructure or a general controller.
In one embodiment, the mobile unit 140 may transmit the received information directly to the base station 108 via a cellular communication network, such as a CDMA cellular network. The mobile unit may transmit this information at time periods of low traffic, periodically, or upon request by the mobile station 108 or the central controller 116.
In another embodiment, the mobile unit 140 may transmit the received information to the central controller 116 over an ad hoc network, or over a multi-hop ad hoc network, as the mobile unit approaches the central unit. Using a multi-hop ad hoc network to transmit information from the mobile units 140 to the central controller 116 reduces transmission power compared to a single ad hoc network.
In another embodiment, the mobile unit 140 may transmit the received information to the central controller 116 via Binary Runtime Environment for Wireless (BREW) protocol. BREW is an application platform that can be loaded on top of the mobile units 140 and the central controller 116 for transmitting information over the internet. The BREW protocol is well known in the art.
In another embodiment, mobile unit 140 transmits the received information to base station 108 via an intermediate hop, such as HBU 122. Transmissions from mobile unit 140 to HBU 122 may be over a low power cellular or ad hoc network. Advantageously, mobile unit 140 need not consume high transmission power to communicate with HBU 122.
In another embodiment, the mobile unit 140 may transmit the received information to the central controller 116 via the user terminal 132. The transmission from the mobile unit 140 to the user terminal 132 as described above may also be made over an ad-hoc network when the mobile unit comes within range of the home computer 132. As described above, the user terminal 132 may transmit the received information to the central controller through, for example, the internet. Preferably, mobile unit 140 does not have to consume high transmission power to communicate with user terminal 132.
In one embodiment, information available at the metering unit 102n may be relayed through multiple mobile units to the base station 108 or the central controller 116. If one mobile unit cannot receive all of the information available at the metering unit 102n due to its mobility, other mobile units that come within range of the metering unit 102n can extract the remaining information, e.g., data packets, from the metering unit 102 n. In this embodiment, data packets received at the base station 108 or the central controller 116 are grouped together according to some set of identifications, such as packet IDs.
In one embodiment, a Mobile Base Unit (MBU)130 may be located within the vehicle 128 and brought into communication range of the remote metering unit 102 a. This embodiment is an alternative to mobile unit 140, which may be used to increase coverage in suburban areas where wireless communication services are not already installed. In this embodiment, MBU 130 may read measurement information from remote metering unit 102a over an ad hoc network, as described above with respect to other embodiments. The MBU 130 also includes a separate computer (not shown) for data storage and post-processing rather than for immediate transmission from the base stations 108 to the central controller 116. In this embodiment, MBU 130 reads remote metering unit 102a as it travels over it. MBU 130 then transmits the received information to base station 108 either directly or through mobile unit 140, HBU 122, and/or user terminal 132.
In one embodiment, HBU 122 collects and sends the report message generated by remote metering unit 102c to base station 108. HBU 122 may receive control messages, commands, and responses to report messages from base station 108 and relay them to remote metering unit 102c for desired actions. It should be noted, however, that in other embodiments HBU 122 may utilize a pre-installed landline communication link 126 directly to the PSTN in order to communicate with central controller 116. This alternative embodiment has the advantage of reduced communication costs if a pre-existing landline communication link 126 already exists within the remote station. In addition, HBU 122 may have an application interface that enables remote scheduling of automatic meter readings, automatic billing information transmissions, and the like, based on control messages sent from central controller 116.
In one embodiment, HBU 122 may include an integrated RS-232 serial port, a consumer electronics bus (CEBus) transceiver, or the like, that enables the interface to connect to user terminal 132 via link 134. The user terminal may comprise a personal computer or a facsimile machine. Link 134 may also be the special connection described above. In this manner, HBU 122 may act as an interface for a consumer to receive and display information sent to HBU 122 from central controller 116. For example, real-time billing information, account status inquiries, and various other value-added services, such as advertising services, may be displayed at the user terminal 132. During peak utility usage periods, real-time pricing information may be transmitted from the central controller 116 to the consumer at the user terminal 122, prompting the consumer to conserve power consumption by shutting down non-critical electronic equipment.
HBU 122 also acts as a "gateway" for other services related to home integration and utility load management. Consider, for example, a CEBus-compliant device 136 connected to HBU 122 via an ad-hoc network connection or Power Line Carrier (PLC) interface 138. The device 136 may be a lighting device, a heating/air conditioning device, a security system, or a home entertainment system. During peak hours, the central controller 116 may send control messages to the device 136 or a group of devices on a common bus to shut down, thereby reducing real-time power loading. Likewise, the consumer can remotely activate and deactivate device 136 by sending control messages from mobile unit 140 to device 136 via base station 108 and HBU 122, or via ad hoc network link 142.
In one embodiment, there is an ad hoc network interface between the remote metering unit 102b and the user terminal 132. In this embodiment, the information measured at the metering device 102b may be transmitted to the user terminal 132 on a regular basis, on demand, on a schedule, or as the portable user terminal 132 comes within range of the metering unit 102 b. The user terminal may process, store, and/or transmit the received information to the central controller over a global communication network, such as the internet.
In each of the above embodiments, multiple remote metering units 102a-102n may simultaneously attempt to send messages over intermediate "hops" (i.e., mobile unit 140, computer terminal 132, HBU 122, or MBU 130) while other mobile subscriber units are also attempting to communicate with the base station. Thus, a technique for avoiding "collisions" between competing remote metering units 102a-102n is provided in U.S. patent No. 5,748,104, which is incorporated herein by reference.
Referring now to FIG. 2, a remote metering unit 200 is illustrated. In one embodiment, which may be used for electric utility meter readings, the measurement device 202 may be a turntable-type or odometer-type motor power consumption monitor and display, as is well known in the art. The reading interface 204 may then be an optical or electromechanical interface adapted to the type of measuring device 202 employed. For example, if the measuring device 202 is a turntable of a motor, the number of disc revolutions represents the power consumption. In such a case, the reading interface 204 may include a light source or photocell that reads a single light pulse for each rotation of the disk. The read interface 204 converts the optical pulses into analog electrical pulses and sends them to an Analog Multiplexer (AMUX)208, which in turn sends them to an analog-to-digital converter (A/D) 210. The a/D converts the analog electrical pulses to a digital signal representative of the number of revolutions counted by the read interface 204 and passes the resulting digital signal to the microprocessor 214. In response to the digital signal, the microprocessor 214 calculates and saves the total power consumption in kilowatt-hours. In a preferred embodiment, the storage interval may be selected from approximately half an hour to one month.
The microprocessor 214 generates a utility consumption message for transmission to the central controller 116 according to a reporting schedule that may be either programmed locally or downloaded from the central controller 116 (see fig. 1) via the paging channel 104. The consumption message is formed by microprocessor 214, then upconverted, modulated, amplified, and transmitted to an ad hoc network interface unit 240, or transmitted by transmitter 216 through antenna 222. Note that in the latter embodiment, the microprocessor 214 configures the translator 220 to transmit only at times other than the allocated paging slot on the paging channel, thereby enabling the remote metering unit 102 to operate in half-duplex without losing incoming messages from the central controller 116. Alternatively, if half-duplex operation is not desired, the switch 220 may be replaced by a conventional duplexer, as is known in the art.
The central controller 116, as previously described, sends control and feedback messages directed to the remote metering units 102a-102 n. These messages may be transmitted through the ad hoc network interface unit 240. Alternatively, these messages may be captured by antenna 222, down-converted and demodulated by receiver 218, and passed to microprocessor 214 for appropriate operation. Note that the microprocessor 214 configures the converter 220 for reception unless an outward transmission is required. The control messages sent by the central controller 116 may include scheduling messages and acknowledgements of receipt of various reporting messages sent by the remote metering units 102.
Further, in the exemplary embodiment of fig. 2, step-down transformers 206a and 206B are coupled to the phase a and phase B power lines of the customer premises, respectively. In a typical power installation version of a U.S. residence, the voltage levels of phase a and phase B are both 120 volts. Step-down transformers 206a and 206B each output an analog voltage level signal that is proportional to the voltage detected on phase a and phase B, respectively. The analog voltage level signals are passed by AMUX 208 to A/D210 where they are subsequently converted to digital voltage level signals. The digital voltage level signals are then passed to the microprocessor 214 through the serial interface 212, where they are then compared to maximum and minimum voltage level thresholds, respectively. In one embodiment, the maximum and minimum voltage level thresholds are programmable, and may be enabled or disabled by control messages from the central controller 116, as desired.
If the digital voltage level signal representing the voltage read on phase A and the digital voltage level signal representing the voltage read on phase B are both between the maximum and minimum voltage level thresholds, then the voltage level adjustments for phase A and phase B are satisfactory and no action is taken. However, if the digital voltage level signal representing the voltage read on phase a or the digital voltage level signal representing the voltage read on phase B is not between the maximum and minimum voltage level thresholds, then the voltage level adjustments for phases a and B are not satisfactory, and the microprocessor 214 generates a fault condition message for transmission to the central controller 116 (see fig. 1). Such a fault condition may occur if there is an excessive "surge" or "under-power" in the voltage level read on phase a or phase B, including a localized outage or brownout. The fault condition message will contain an encoded representation of the actual voltage read on phase a and phase B. The microprocessor 214 may generate a fault condition message for transmission to the central controller 116. Furthermore, the central controller 116 may interrogate the remote metering unit 102 and instruct it to report not only the present consumption reading, but also the current voltage levels detected on phases a and B.
Further, in the embodiment shown in fig. 2, a tamper sensor 238 generates an analog tamper signal upon any attempted modification or disconnection of the remote metering unit 102. Tamper sensor 238 may be, for example, a mercury switch, or a proximity switch as is known in the art. This is desirable in utility metering applications, as it is very common to tamper with metering meters in order to "steal" utility services. Tamper sensor 238 is a security feature that can remotely detect theft because nobody will frequently access remote metering unit 102 for visual inspection. The analog tamper signal is passed through AMUX 208 to A/D210 and subsequently converted to a digital tamper signal. The digital tamper signal is passed to the microprocessor 214 through the serial interface 212. Microprocessor 214 may generate a fault status message for transmission to central controller 116 or it may provide memory storage for the digital tamper signal for delayed reporting. In the event that the remote metering unit 102 is disconnected, the digital tamper signal is saved in memory for later retrieval.
In the embodiment shown in fig. 2, CEBus interface 224, power line transceiver 226, and twisted pair transceiver 234 are shown as integrated parts of remote metering unit 102. It should be noted, however, that these "gateway" devices may be located in HBU 122 (see fig. 1). Further, it should be noted that whether twisted pair transceiver 234 or power line transceiver 226 are located integrally with remote metering unit 102, or whether they are present at all, may depend on the nature and configuration of the installation site. It should also be noted that although CEBus interface 224, power line transceiver 226, and twisted pair transceiver 234 are shown in fig. 2 as physically separate blocks, they may be integrated into a single Very Large Scale (VLSI) Application Specific Integrated Circuit (ASIC), or even combined into microprocessor 214. VLSI ASIC technology is well known in the art.
In one embodiment, the CEBus interface 224 includes a flash EPROM programmed with proprietary code required to run the various advanced services described above. In addition, the CEBus interface 224 includes non-volatile memory for storing CEBus system configuration parameters. Finally, CEBus interface 224 includes the circuitry necessary for interfacing with microprocessor 214 as well as power line transceiver 226 and twisted pair transceiver 234. For example, the CEBus interface 224 may also include an embedded UART (not shown) for transmitting at higher data rates over the twisted pair transceiver 234. CEBus controllers and interfaces are well known in the art. Power line transceiver 226 and twisted pair transceiver 234 each include the circuitry necessary to perform carrier modulation. This may include amplifiers, receivers, converters, and various passive components. Power lines and twisted pair transceivers are also well known in the art.
In operation, control or information messages originating from the central controller 116 or from the mobile unit 140 may be received either through the ad hoc network interface unit 240 or through the receiver 218 and passed to the microprocessor 214 and then routed to the CEBus interface 224. In response to the control or information message, CEBus interface 224 generates a PLC encoded message for transmission by twisted pair transceiver 234 or power line transceiver 226, or both. PLC encoded messages are transmitted over power lines 228 and 230, respectively, or over twisted pair 232. The CEBus compliant device 136 receives the PLC encoded messages, decodes them, and takes appropriate action.
Fig. 3 illustrates one embodiment of a mobile unit 140, such as a cellular telephone or Personal Digital Assistant (PDA), operating in the system 100 of fig. 1. The mobile unit 140 includes an antenna 300 for transmitting and receiving cellular voice and data. The antenna 300 is coupled to a transmit-receive converter 302 for distinguishing the receiver path from the transmitter path. The transmit-receive converter is coupled to a receiver circuit 308 forming a receiver path and to an amplifier 304 and a transmit circuit 306 forming a transmitter path. The amplifier 304 is further coupled to a power conditioning unit 310, which power conditioning unit 310 provides control for the amplifier 304. Amplifier 304 receives the transmission signal from transmit circuit 306.
The cellular signal received via the antenna 300 is provided to a power control unit 314, which implements a closed loop power control scheme. The power control unit 314 is coupled to a communication bus 318. The communication bus 318 provides a common connection between the modules within the mobile unit 140. The communication bus 318 is also coupled to a memory 322 and a recovery adjustment unit 316. Memory 322 stores computer readable instructions for various operations and functions that may be used for mobile unit 140. Processor 320 executes instructions stored in memory 322. For normal operation, the power control unit generates a power control signal to the power conditioning unit 310 via the multiplexer 312. Power adjustment unit 310 then transmits the power control signal as an amplification level to amplifier 304.
When the mobile unit 140 comes within range of another device equipped with an ad hoc network interface, the mobile unit 140 may receive and/or transmit information through the ad hoc network interface 324. Information received via the ad hoc network interface 324 may be stored in a memory unit 322 and/or processed by the processor 320, which may be a Digital Signal Processor (DSP).
According to one embodiment, the transmission of information from the mobile units may be periodic, either on demand from the base stations or central controller, or according to a planned schedule, which is managed by the wireless infrastructure or central controller. The wireless infrastructure may track the location and/or movement of the mobile unit to manage the transfer of data from the mobile unit to the central controller. In one embodiment, when the current location information of the mobile unit indicates that the mobile unit is in the vicinity of the central controller or intermediary wireless device, the mobile unit may be instructed to transmit information to the central controller or intermediary wireless device. This process better manages network resources and conserves battery life in the mobile unit as compared to the mobile unit transmitting information from a distance away from the central controller. In another embodiment, the mobile unit may be scheduled to transmit information to the central controller or intermediate wireless device at a scheduled time when the mobile unit's condition indicates a time of day or week that the mobile unit is typically near the central controller or intermediate wireless device. This intelligent plan for information transfer helps manage network resources and conserves battery life in the mobile unit, as compared to when the mobile unit is transferring information from a distance away from the central controller or when network traffic is busy.
As such, the disclosed embodiments use low power, low cost, and ad hoc network enabled wireless communication devices to provide flexible reading and control of remote telemetry devices while providing advanced consumer services to consumers. The wireless communication device receives measurement information from the metering device and communicates such information to the central controller in accordance with a planned data transfer scheme, thereby avoiding expensive and high power transmitters and elaborate network planning.
The previous description of the embodiments is provided to enable any person skilled in the art to make or use the present invention. Modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.