A communication system

Abstract

Communication system suitable for transmitting data at low data rates from a plurality of independent radio frequency transmitters via a low power wide area network (LPWAN). A receiver receives encryp

Description

15 01 24 Field This invention relates to a communication system. More particularly, but not exclusively, the invention relates to a communication system which is suitable for use to transmit data at low data rates, from a plurality of independent radio frequency transmitters, via a low power wide area network (LPWAN). Background There is an increasing tendency to deploy so-called smart utility meters, which are capable of recording amounts of kilowatt hours of electricity and volumes of gas used at a premises, and volumes of water used by private residential and commercial customers. Such smart utility meters or smart meters are used in resource monitoring systems to record consumption information which is displayed locally on an odometer for checking and inspection and is increasingly recorded in a digital memory. One benefit of these so-called smart meters with resource monitoring systems, is that they do not require an attendant to repeatedly read and check them to obtain the amount of energy or volume of water consumed. Instead, many existing smart meters are configured to transmit their odometer readings, from a local radio frequency (RF) transmitter, when interrogated by a radio frequency receiver. One way in which smart meters are read is by mobile radio receivers, which in some systems are housed in vehicles. These make ad-hoc meter reading more efficient and smart meters are often equipped with a short-range radio transmitter to facilitate automatic meter reading (AMR). The mobile radio receivers interrogate the smart meters, fitted with the radio frequency (RF) transmitters, as a vehicle approaches a property. The radio receiver is usually installed in a vehicle which drives past the smart meters, within a range and interrogates the meters and uploads meter readings and stores them in a memory for subsequent processing at a bill payment or payment reconciliation centre. These vehicle based systems have been found to remove the need for continual meter checking which also reduces operating costs as well as meter reading errors. 15 01 24 Another advantage with vehicle mounted systems, and networks which include these smart meters, particularly where smart meters record volumes of water used, is that the smart meters provide a continuous indication of usage and so their individual results can be aggregated to gather information in order to predict local usage within districts or towns; to identify likely locations of leaks; and to perform predictive maintenance. Currently the range of these RF transmitters is limited to a few metres or tens of metres. The technique used to remotely read so-called ‘smart meters’ relies on a combination of established techniques including received signal strength (RSS); and well known ‘ping and ring’ interrogation techniques to the RF transmitters associated with smart meters, to confirm the identity or its unique number of a smart meter; to relate this to a property (or account holder); and finally to retrieve a value corresponding to the amount of water that has been used since a previous meter reading. The recorded number is typically indicative of the number of litres or m3 of water used. Despite being more efficient than individual meter inspections, these mobile meter interrogation systems still require an operator to drive a vehicle along a pre-planned route, in a neighbourhood where meters fitted with RF transmitters have been installed. AMR is typically performed by a short-range hand-held, or vehicle-mounted RF receivers which wirelessly collect transmitted data packets which include meter reading data, typically within 10m to 50m range. AMR signals are encrypted and carry comprehensive information in each message that does not require continual retransmission and can be considered as a data overhead. AMR has required personnel to drive a vehicle which has to be fitted with specialist equipment and was inevitably subject to all the delays in traffic and obstacles or intervening vehicles which disrupted signal reception. Consequently AMR did not always obtain data from every smart meter along a particular route. This therefore entailed a revisit on a subsequent occasion which added to the cost of operating AMR systems. 15 01 24 Another problem with vehicle-based AMR systems was that vehicles tended to be polluting and so contributed to the carbon footprint of operating the AMR system There was also the need to continual revisiting a neighbourhood or location at regular intervals (monthly or quarterly) in order to continually update user accounts. Furthermore, many such vehicles were required in the AMR system each of which in turn required a driver. Inevitably such systems need significant capital investment. As a consequence, although AMR systems offer advantages by using vehicles to collect readings which were previously carried out by pedestrian inspectors or meter reading personal, there is still a need for personal albeit less personal who are required to visit an area in order to record usage volumes of water. Despite AMR systems there is still a need for a more rapid data retrieval system which obtains individual meter readings, in as close to real time as possible, thereby indicating actual water usage. Prior Art European patent application EP 3411864A1 (Apana Inc) discloses a technique for improving battery life performance of end devices in resource monitoring systems, such as in automatic utility meters, which transmit data using low-power, wide area networks (LPWANs). Recent advances in LPWAN (low-power, wide-area network) technology enable longer-range transmission of signals viable and these distances sometimes can exceed several kilometres. When applied to resource monitoring systems the technique is often referred to advanced meter infrastructure (AMI) and one of its objectives is to enable automatic reading of utility meters. Utility companies recognise AMI has many advantages over AMR, including the option of having less expensive vehicles, reducing their environmental impact and the capability of capturing up-to-date digital information to discover inefficiencies and to better inform and influence consumers. 15 01 24 AMR meters are valuable assets that may be wirelessly retrofitted to extend range and acquire the benefits of AMI. However, there is an inherent challenge that AMR data packets are too large to relay over existing AMI infrastructure because they contain encrypted data and encryption keys which require a significant amount of data. Therefore one object of the invention is to overcome the problems of AMR and to provide a system which is automated and requires less personnel. Another object of the invention is to process encrypted overhead data which is inherent in AMR data packets and render them suitable for transmission via AMI infrastructures. A further object the invention is to remove polluting vehicles from roads in order to reduce the carbon footprint of automated meter reading systems. A yet further object of the invention is to provide a system which is capable of obtaining water usage data more quickly and in real time or quasi-real time in order to use the data for purposes of infrastructure management and maintenance. Summary of the Invention According to a first aspect of the invention there is provided a low power wireless local area network (LPWAN) communication system comprises: a receiver which is operative to receive encrypted signals transmitted from separate transmitters, at least some of the signals are relayed to the receiver via a bridge; an arbitrator arbitrates with the bridge and selects a signal to be decrypted in dependence upon an operator specified criterion; a processor, in a decryption device, requests from a secure repository, a decryption key, corresponding to the selected signal to be decrypted; a disassembler disassembles the decryption key into a plurality of key parts; a transmitter transmits the key parts to the receiver; and the processor reassembles each of the key parts to obtain a key which the decryption device uses to decrypt the selected signal. 15 01 24 The invention overcomes the problems associated with existing systems because it operates to down-size pre-encrypted data, thereby making multiple messages viable whilst optimising in-field battery life by utilising existing AMI infrastructure. The invention therefore preserves large amounts of existing assets effectively by enabling AMR-to-AMI bridging. Typically length of messages in LPWAN are limited and their so-called message budget is restricted by industrial scientific medical (ISM) frequency band practice, where power and transmission range are limited by duty cycle described in the UK by EN                    300                    220-2                    v3.2.1 https: / / www.etsi.orq / deliver / etsi en / 300200 300299 / 30022002 / 03.02.01 60 / en 300 22002v030201p.pdf Incoming encrypted messages are typically 44-bytes so the invention renders LPWAN retransmission of these data packets more efficient by in less than 12-bytyes, thereby optimising existing LPWAN, especially SIGFOX (RTM) infrastructure. According to a second aspect of the invention there is provided a method of interrogating a plurality of low power wireless transmitters, each associated with a utility meter, by deploying a receiver in a low power wireless local area network (LPWAN) communication system to receive encrypted signals transmitted from each transmitter, compiling a network map of usage and overlaying the map data onto supply data in order to optimise efficiency of the system by targeting specific transmitters and associated utility meters. In some systems the receiver is operative to receive encrypted signals transmitted from separate transmitters wherein at least some of the signals have been relayed to the receiver via a bridge. Where signals are encrypted, an arbitrator arbitrates with the bridge and selects a signal to be decrypted in dependence upon an operator specified criterion such as received signal strength indicator (RSSI), prescribed permitted (whitelist) utility meters or proscribed or prohibited (blacklist) utility meters. 15 01 24 Where the utility meters are used to measure volumes of water that have been used, the method is able to obtain a value for a total amount of water supplied and average usage in a district or zone. It will be appreciated that techniques in which prior knowledge of meter identities and location; total water usage in a specified neighbourhood and knowledge of the total amount of water supplied to that same neighbourhood, enable water supply companies to estimate leakage which occurs in a water supply network and to pinpoint problematic zones. The invention enables multiple meters to connect via one device and exploit the LPWAN message budget. In some embodiments the communication system includes a received signal strength (RSS) is the strength of a received signal measured at the receiver's antenna. The RSS is determined by the transmission power, the distance between the transmitter and the receiver, and the radio environment. The invention is vertically scalable meaning it enables a large installation base using wireless tools in under a few minutes by unskilled operators thus minimising associated installation time, cost and effort. A preferred embodiment of the invention exploits ad-hoc return paths in LPWAN systems to configure decryption keys on the device. In a preferred embodiment, the invention uses an interface on a mobile device that aids installers to inspect and monitor the deployment status and any associated information streams. Preferably decryption keys may be implemented using a local wireless systems, such as wireless protocols including Bluetooth (RTM), Bluetooth Low Energy, (RTM), Zigbee (RTM), and Wi-Fi. Single or multiple keys may be configured on the device The installation process may be used in the absence of a local or mobile interface by utilising a downlink or bidirectional channels of the LPWAN and a carousel in headend software. 15 01 24 The device may be pre-paired with the key or keys in embedded in factory before installation. These keys may be remotely reconfigured by the headend software. The invention tackles various installation and configuration scenarios with a system of devices, wireless communications especially LPWAN, local interfaces and computer systems. The purpose of the invention is to match utility meters to their encryption keys and manage the seamless uploading of the key, or keys, to the device. The key is applied to the incoming AMR message and the resultant decrypted payload is reformatted for onwards retransmission over LPWAN or similar wireless communications protocol. Preferred embodiments of the invention will now be described, by way of examples only and, with reference to the Figures in which: Brief Description of the Figures Figure 1 shows an overview of a low power wireless local area network (LPWAN) communication system including a utility meter, a decryption device, a LPWAN infrastructure and a cloud based computer centre; Figure 2 is a diagrammatical representation of an operational modes of the low power wireless local area network (LPWAN) communication system and how a utility meter, a decryption device is accessed from a remote location, such as a cloud based computer centre. Figure 3 shows a diagrammatical representation of separate operational modes of the low power wireless local area network (LPWAN) communication system and how a utility meter, a decryption device, a LPWAN infrastructure and a cloud based computer centre. Figure 4 shows a diagrammatical representation of separate operational modes of the low power wireless local area network (LPWAN) communication system and how a utility meter, a decryption device, a LPWAN infrastructure and a cloud based computer centre. Detailed Description of Preferred Embodiments of the Invention 15 01 24 Referring to Figure 1 is a diagrammatical overview of a system showing a meter 10 with its encryption key; a short-range radio frequency relay 20 tackles various installation and configuration scenarios with a system of devices, wireless communications especially LPWAN, local interfaces and computer systems. The system effectively checks all received signals and determines which received signal relates to a desired or required output signal from a smart meter. Once a hierarchy of appropriate signals is established an arbitration step takes place. Arbitration occurs at the bridge which requests a key associated with an appropriate signal in order to decrypt the signal. However, as the size of the key is so large, it would take an inordinately long time (typically as long as 32 or 48 bytes with a encryption key of up to 128 or 265 bits) in order to transmit it via the LPWAN. Therefore, the bridge instructs the key to be disassembled and transmitted as several sub-keys or key parts which are labelled so that when they are received, the key parts can be reassembled into the encryption key. Reassembling of the sub-keys and verification of the authenticity and validity of the reassembled parts into the key, are preferably performed at the bridge. Referring to Figures 2 to 4 generally and as a series of steps as described in the example below. 1. Existing meters transmit encrypted payload with so-called in-the-clear metadata which includes data relating to a serial number of the smart utility meter. The low power wireless local area network (LPWAN) communication system exploits unencrypted sections of message to detect suitable single or multiple utility meters 10A to 10C and creates a list of them from their respective serial numbers. 2. Asset information, including locations, serial numbers and encryption keys are received and stored in database 80A. 3. Encryption key(s) are processed by a processor 80B operating in accordance with software at a server 80C. Resultant data is stored in database 80 in a form suitable for downlinking to the decryption device 90A. Transmitted data may or may not be in segments. 15 01 24 Encryption keys 70A to 70C, associated by their serial number, (shown in Figure 2), are allocated a destination decryption device 90A. The destination decryption device contains a unique identifier and a list of keys 70A to 70C which are stored at 40. 4. UPLINK the list is transmitted via 5 to 3. DOWNLINK The encryption key(s) are reassembled in the device and matched, by serial number, to the list established in 1. 5. UPLINK The encryption key(s) may be sent in segments using unique identifiers and sequence checking to a destination device with a unique identifier. This UPLINK step may be an enquiry signal sent from the decryption device 90A to the database 80A in order to interrogate it. Alternatively a data packet is transmitted by the LPWAN 60 DOWNLINK The device will transmit a range of messages that contain metadata, payload, configuration information, alerts and alarms. Figure 1 shows an example of an existing system in which meters 10 transmit encrypted payload together with so-called ‘in-the-clear metadata’ which typically includes a serial number of the transmitter which is linked to a property or location. Figure 2 shows a operating as a decryption device 90A requests from a secure repository. A decryption key 70 corresponds to the selected signal to be decrypted. A disassembler disassembles the encryption key into a plurality of key parts shown diagrammatically as 100. A short- or a long-range range transmitter, such as SIGFOX (RTM), LoRaWAN (RTM), NB-loT or MIoTY LPWAN, a Bluetooth (RTM) or Bluetooth Low Energy (RTM), wireless transmitter transmits single or multiple key parts to a remote receiver which may be a receiver in a building, street furniture, underground chamber or specialist enclosure. A processor, which is typically part of a bespoke records system reassembles each of the key parts to obtain a key which the decryption device uses to decrypt the selected signal. 15 01 24 At this time the invention therefore matches utility meters to their encryption keys, manufacturer ID and serial number and manages uploading of a digital key to the device. Digital keys are applied to an incoming AMR message and the resultant decrypted data or payload is reformatted for onwards retransmission over the LPWAN or similar wireless communications protocol. Figures 3, 4 and 5 show steps in this transmission and decryption procedure. A device detects suitable single or multiple meters and to creates a list from their serial numbers. A low power wireless local area network (LPWAN) communication system includes a receiver 60 which receives encrypted signals transmitted from separate transmitters 90B, at least some of the signals are relayed to the receiver via a bridge. An arbitrator 82 arbitrates with the bridge and selects a signal to be decrypted in dependence upon an operator specified criterion. A processor 20, in a decryption device, requests from a secure repository, a decryption key, corresponding to the selected signal to be decrypted. A disassembler disassembles the encryption key into a plurality of key parts and aa transmitter transmits the key parts to the receiver. The processor reassembles each of the key parts to obtain a key which the decryption device uses to decrypt the selected signal. Referring to Figure 1 asset information including locations of smart utility meters, their serial numbers and encryption keys are received and input into the database 40. The encryption key(s) 50 are processed by the processor 20 operating under control of software. When processed data is rendered in a suitable format for onward transmission or downlinking to the smart utility meter 10. In this format the data may or may not be in segments. Keys 50 are associated with their serial number 40 are allocated a destination device (not shown). The destination device 20 contains a unique identifier and a list of keys. 4. UPLINK the list fromi is transmitted via 5 to 3. 5. During a so-called UPLINK stage, encryption key(s) 70A to 70C are optionally transmitted in data packets or segments using unique identifiers and sequence 15 01 24 checking to a destination device with a unique identifier in order to facilitate reassembly and verification. Referring to Figure 3 during the so-called DOWNLINK stage, encryption key(s) 70 are reassembled in the destination device 90C and matched, by serial number, to the list that is stored at the database 80A. The transmitter 90B device transmits a range of messages that contain metadata, payload, configuration information, alerts and alarms. During a so called ‘downlink’ stage the 40 transmits a range of messages that contain metadata, payload, configuration information, alerts and alarms. This is shown in Figures Optionally software, for example which employs so-called STACKFORCE (RTM) protocols enable collection of data using remote meter reading techniques. Software is embedded in utility meters and these enable keys to be used to decrypt messages and enable meter readings (time, date, location meter identity and amount of utility used) to be transmitted. It will be appreciated that the invention has been described, by way of examples only, and variation may be made to the aforementioned embodiments, without departing from the scope of the invention as defined by the claims.

Claims

15 01 241. A low power wireless local area network (LPWAN) communication system comprises: a receiver which is operative to receive encrypted signals transmitted from separate transmitters, at least some of the signals are relayed to the receiver via a bridge;an arbitrator arbitrates with the bridge in a smart meter and selects a signal to be decrypted in dependence upon an operator specified criterion;a processor, in a decryption device, requests from a secure repository, a decryption key, corresponding to the selected signal to be decrypted;a disassembler disassembles the decryption key into a plurality of key parts;a transmitter transmits the key parts to the receiver; andthe processor receives the key parts from the receiver and reassembles each of the key parts to obtain a key which the decryption device uses to decrypt the selected signal.

2. An LPWAN communication system according to claim 1 includes a means which determines received signal strength (RSS) of a received signal and outputs a value at a receiver antenna.

3. An LPWAN communication system according to claim 1 wherein an arbitrator determines which of a plurality of signals, based on received signal strength (RSS), is to be processed.

4. An LPWAN communication system according to any preceding claim wherein the ad-hoc return paths in an LPWAN network, are employed to configure decryption keys on the device.

5. An LPWAN communication system according to any preceding claim wherein the bridge requests a key associated with an appropriate signal in order to decrypt the signal.15 01 246. An LPWAN communication system according to claim 5 wherein, in the event that the key exceeds a predefined size, (typically in excess of 32 bytes), the bridge instructs a key bank to disassemble the key into key parts7. An LPWAN communication system according to claim 5 wherein, the disassembled key parts are labelled with a label so that when key parts are received, they can be reassembled into the decryption key.

8. An LPWAN communication system according to claim 6 or 7 wherein the bridge receives the key parts and reassembles them to obtain the decryption key.

9. An LPWAN communication system according to any of claims 6 to 8 wherein the bridge verifies and authenticates the validity of the reassembled decryption key.

10. An LPWAN communication system according to any preceding claim wherein at least one decryption key is processed by a processor operating in accordance with software to be suitable for downlinking to a destination device.

11. An LPWAN communication system according to any of claims 6 to10 wherein data is supplied by the key bank in segments and at least one decryption key is processed by a processor, operating in accordance with software, and processed data is stored in a database.

12. An LPWAN communication system according to claim 11 wherein the processor is operative to instruct the bridge to optimise ad-hoc return paths in LPWAN infrastructure to configure the decryption keys.

13. The LPWAN communication system according to any preceding claim includes a mobile communication device, operating in accordance with application specific software (APP), to provide an interface to enable a user to deploy and check a status and associated asset information from a utility meter.

14. The LPWAN communication system according to claim 13 wherein the asset information, includes a location of a utility meter, a serial number of a utility meter and a decryption key associated with a utility meter.

15. The LPWAN communication system according to any preceding claim wherein keys are allocated a destination device in dependence upon their serial number.

16. A smart meter includes: a bridge which requests a key associated with an appropriate signal and wherein the bridge is operative to disassemble the key and a transmitter which is operative to transmit the dissembled key as sub-keys or key parts; and a destination device which is operative to communicate with the LPWAN communication system according to any of claims 1 to 15.

17. A method of operating a device using the communication system according to any of claims 1 to 15.

18. A method of reading a smart meter using the communication system according to any of claims 1 to 15.15 01 24

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