Power management and security for wireless modules in “machine-to-machine” communications
Inventors
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Publication Number
US-10003461-B2
Publication Date
2018-06-19
Expiration Date
Abstract
Methods and systems are provided for power management and security for wireless modules in “Machine-to-Machine” communications. A wireless module operating in a wireless network and with access to the Internet can efficiently and securely communicate with a server. The wireless network can be a public land mobile network (PLMN) that supports wireless wide area network technology including 3rd generation (3G) and 4th generation (4G) networks, and future generations as well. The wireless module can (i) utilize sleep and active states to monitor a monitored unit with a sensor and (ii) communicate with wireless network by utilizing a radio. The wireless module can include power control steps to reduce the energy consumed after sending sensor data by minimizing a tail period of a radio resource control (RRC) connected state. Messages between the wireless module and server can be transmitted according to the UDP or UDP Lite protocol with channel coding in the datagram body for efficiency while providing robustness to bit errors. The wireless module and server can utilize public key infrastructure (PKI) such as public keys to encrypt messages. The wireless module and server can use private keys to generate digital signatures for datagrams sent and decrypt messages received. The communication system between the wireless module and the server can conserve battery life in the wireless module while providing a system that is secure, scalable, and robust.
Core Innovation
The disclosed methods enable a wireless module to transmit sensor measurements to a server and promptly place its processor and radio into sleep and radio off states. Communication uses module identity, module-encrypted data, or UDP datagrams, while server responses include a security token, channel coding, digital signature, or sleep timer. The module transitions to sleep and off states before network-controlled RRC tail, DRX activity, or radio-resource connection release.
Signed module messages provide an alternative to digest authentication with lower communication overhead, enabling the server to ignore unauthenticated messages. A single message-and-response round trip reduces radio-active time by an exemplary 250 milliseconds and energy use by about 0.5 joules. The methods further feature timer-based waking and sleep, response authentication, and early radio power-down to reduce battery use.
Claims Coverage
The claims identify three independent claims: claims 1, 8, and 14. They cover wireless-module methods for sensor-measurement transmission and machine-to-machine communications, comprising three inventive features.
Sensor transmission with early radio power-down
Claim 1 covers a wireless module changing its processor and radio from sleep and radio off states to active and connected states, transmitting a sensor measurement with a server address and module identity, and receiving a response containing channel coding, a security token, and a module instruction with a sleep timer. The processor and radio return to sleep and radio off states while RRC_CONNECTED and before DRX use. Dependent claims add single-datagram UDP communication during the radio connected-to-off interval, timer-driven sensor recording without user input, response digital signature verification using a server public key, and radio-off criteria.
Encrypted sensor transmission with timer-controlled sleep
Claim 8 covers reading a first sleep timer, module identity, key, and server address from nonvolatile memory; using the first timer to wake the processor and connect the radio; transmitting encrypted sensor measurement data; and receiving a response with channel coding, a security token, and a second sleep timer instruction. The processor and radio return to sleep and radio off states before radio-resource connection release. Dependent claims add single-datagram UDP transport, differing first and second sleep timers in a battery-powered device, server-encrypted response decryption, actuator control, and digital signature verification.
Encrypted UDP sensor communication with signed-token response
Claim 14 covers reading a module identity, key, and server address from nonvolatile memory, connecting the radio, and sending a UDP packet containing encrypted sensor measurement data and a security token. The module receives a response containing the security token and its digital signature, then transitions the processor to sleep and radio to off. Dependent claims add radio-off criteria powering down at least two listed components, single-datagram limits, battery-powered sensor device configurations, response decryption before radio power-down, and sending a detach message while RRC_CONNECTED and before DRX use.
The three independent claims cover sensor transmission followed by early power-down, timer-controlled transmission of encrypted sensor data, and encrypted UDP sensor communication with a signed-token response. Associated claim features address UDP transport limits, timer-driven recording, response authentication, actuator control, and radio-state transitions.
Stated Advantages
Signed module messages provide lower communication overhead compared to digest authentication, with one message-and-response round trip capable of reducing radio-active time by an exemplary 250 milliseconds and energy use by about 0.5 joules.
The server can ignore unauthenticated messages.
Reduces battery use by promptly powering down the radio and/or processor before network-controlled RRC tail or DRX activity.
Documented Applications
Wireless-module transmission of sensor measurements and related data to a server in machine-to-machine communications.
A mobile device with a battery and sensor recording a sensor measurement without user input.
A monitored wireless module connected through a public land mobile network and the Internet to a server, within a system that includes a certificate authority.
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