Patent Application
20160337966
The present invention relates generally to data transmission, and in particular to a system and method for low power data transmission.
In a wired or wireless equipment network, an energy efficient synchronization mechanism is desirable to minimize node power consumption. Reduced power consumption is a critical factor in, for example, military and aerospace fields where size, weight, and increased length between maintenance cycles are considerations for fielded equipment. Also, in military and aerospace applications, it may be desirable, for example, to prevent wireless nodes from announcing the node's presence under certain circumstances, such as while in flight. Therefore, it is desirable to reduce the node's power consumption as much as possible.
A method of low power data transmission includes transmitting, by a network coordinator, a sleep/wake schedule that includes a sleep period and a wake period for a node; receiving, by the node, the first sleep/wake schedule; passively listening, by the node, for commands from the network coordinator during the wake period; and powering down, by the node, data communication capabilities of the node during the first sleep period.
A data transmission system includes a network coordinator and a node. The node is configured to receive a schedule from the controller. The schedule includes a wake period and a sleep period. The node is configured to passively listen for commands from the network coordinator during the wake period, and to not listen for the commands from the network coordinator during the sleep period.
A node includes a power source, a timer, and a controller. The controller receives a wake/sleep schedule from an external source and is configured to wake the node and listen for external commands while the node is in a wake state, and power down the node while the node is in a sleep state. The node remains in the wake state for a wake period and remains in the sleep state for a sleep period.
A system and method is disclosed herein for providing low power data transmission. The system includes a plurality of nodes such as, for example, wireless sensors, and a base station that includes, for example, a network coordinator. Each node may receive a wake/sleep schedule from the network coordinator. The wake/sleep schedule includes a wake interval period, and a time out period. The wake interval period is the time between wake cycles for the node and the time out period is the amount of time the node remains awake prior to entering a new sleep cycle. During the wake cycle, the node passively listens for, and executes commands from, the network coordinator. By only listening for and executing commands during the wake cycle, the amount of power utilized by the node is greatly reduced. This is advantageous in systems, for example, such as fielded wireless sensors that run on battery power or power derived from an energy harvester.
Network coordinator 14 may be configured to provide a wake/sleep schedule to nodes 12a-12n over, for example, the communication network. Wireless sensors, for example, receive and execute commands from network coordinator 14. These commands may be, for example, instructions to collect data, transmit data, or perform other functions of the wireless sensors. For many nodes 12a-12n, the node 12a-12n spends a majority of time in an idle mode, not receiving or executing commands from network coordinator 14. If the node 12a-12n remains fully powered during these idle times, power is unnecessarily consumed. By scheduling sleep cycles for each node 12a-12n, the amount of power utilized by each node 12a-12n is greatly reduced. This is beneficial, for example, for wireless sensors that run on battery power. This may also be useful in military scenarios, for example, in which wireless sensors must remain deployed in the field and increased time between maintenance cycles may be crucial. The wake/sleep schedules may be set, for example, automatically by an algorithm running on network controller 14, or manually by an operator through network coordinator 14. Nodes 12a-12n may store the wake/sleep schedule locally in, for example, a register, NVM, or other storage device.
With continued reference to
Node 12a enters its sleep cycle upon completion of its timeout interval (TO_1) which may be tracked, for example, using timer 20 of node 12a. However, if node 12a is presently executing commands upon timer 20 reaching the end of the timeout interval (TO_1), node 12a may finish executing commands prior to entering the sleep cycle. Node 12a would then enter the sleep cycle following completion of the commands. The sleep cycle may include, for example, node 12a operating in a low power mode in which a majority of its systems, including its communication systems, are powered down. This saves power compared to prior systems in which, for example, the data transmission components remained powered on at all times to continuously listen for commands from network coordinator 14.
The wake interval period (WI_1) is a measure of time between wake cycles for node 12a. Timer 20, which may be the same timer also used to track the timeout period (TO_1), or may be a separate timer, measures the time elapsed since the start of the previous wake cycle. Upon reaching the WI_1 threshold, node 12a is woken up from its sleep cycle, powering on the necessary components to passively listen for commands from network coordinator 14. This may be implemented for all nodes 12a-12n as illustrated in
With continued reference to
At step 106, it is determined if it is time for node 12a to wake up from its sleep cycle. This may be determined using timer 20 and the stored wake interval period for node 12a. Timer 20 may, for example, reset each time node 12a wakes up. Once timer 20 reaches the end of the wake interval period, node 12a is ready to once again wake up. If node 12a is ready to wake up, method 100 proceeds to step 108. If node 12a is not ready to wake up, method 100 proceeds to step 110. At step 110, node 12a is in the sleep state and method 100 returns to step 106 to determine if it is time for node 12a to wake up.
At step 108, node 12a is not in a sleep state. This may comprise node 12a having its data communication hardware powered on. Node 12a listens passively for commands from network coordinator 14. At step 112, if node 12a is receiving commands, method 100 returns to step 108 and node 12a executes those commands. If node 12a is not currently receiving commands from network coordinator 14, method 100 proceeds to step 114 and determines if the timeout interval period has ended. Timer 20, or a separate timer, may be utilized to determine if the timeout period has ended. For example, upon wakeup, timer 20 may be reset, or may have its present time noted. Upon reaching the end of the timeout interval period, if no commands are currently being received, method 100 proceeds to step 110 to enter the sleep state. If the timeout interval period has not ended, method 100 returns to step 108 and node 12a continues to listen for commands. Method 100 may run indefinitely until, for example, the system is shut down, or node 12a receives an updated wake/sleep schedule from network coordinator 14. While described with relation to node 12a, method 100 may be implemented for any/all nodes 12a-12n.
Discussion of Possible Embodiments
The following are non-exclusive descriptions of possible embodiments of the present invention.
A method of low power data transmission includes transmitting, by a network coordinator, a sleep/wake schedule that includes a sleep period and a wake period for a node; receiving, by the node, the first sleep/wake schedule; passively listening, by the node, for commands from the network coordinator during the wake period; and powering down, by the node, data communication capabilities of the node during the first sleep period.
The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing method, further including transmitting, by the network coordinator, a second sleep/wake schedule that includes a second sleep period and a second wake period for a second node; receiving, by the second node, the second sleep/wake schedule; passively listening, by the second node, for commands from the network coordinator during the second wake period; and powering down, by the second node, data transmission capabilities of the second node during the second sleep period.
A further embodiment of any of the foregoing methods, wherein the first and second sleep periods are equal.
A further embodiment of any of the foregoing methods, wherein the first and second sleep periods are not equal.
A further embodiment of any of the foregoing methods, wherein the first wake period is defined by a timeout interval, and wherein the first sleep period is defined by the timeout interval subtracted from a wake interval, and wherein the first sleep/wake schedule includes the timeout interval and the wake interval.
A further embodiment of any of the foregoing methods, wherein passively listening, by the first node, for commands from the network coordinator during the first wake period includes counting, by a timer, a first time period count during the first wake period; and passively listening, by the first node, for commands from the network coordinator until the first time period count is greater than or equal to a count corresponding to the timeout interval.
A further embodiment of any of the foregoing methods, wherein powering down, by the first node, the data communication capabilities of the first node during the first sleep period includes counting, by the timer, a second time period count during the first wake period and the first sleep period; powering down, by the first node the data communication capabilities of the first node while the second time period count is greater than the count corresponding to the first timeout interval and less than a count corresponding to the wake interval; and power up, by the first node, the data communication capabilities of the first node when the second time period count is equal to the count corresponding to the wake interval.
A data transmission system includes a network coordinator and a node. The node is configured to receive a schedule from the controller. The schedule includes a wake period and a sleep period. The node is configured to passively listen for commands from the network coordinator during the wake period, and to not listen for the commands from the network coordinator during the sleep period.
The data transmission system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing system, wherein the first schedule is a default schedule.
A further embodiment of any of the foregoing systems, wherein the first schedule is received by the first node from the network coordinator.
A further embodiment of any of the foregoing systems, further including a second node configured receive a second schedule from the controller, wherein the second schedule includes a second wake period and a second sleep period, and wherein second node is configured to passively listen for commands from the network coordinator during the second wake period, and wherein the second node is configured to not listen for the commands from the network coordinator during the second sleep period.
A further embodiment of any of the foregoing systems, wherein the first sleep period and the second sleep period are equal.
A further embodiment of any of the foregoing systems, wherein the first sleep period and the second sleep period are not equal.
A further embodiment of any of the foregoing systems, wherein the first and second nodes are battery or energy harvester powered wireless sensors.
A further embodiment of any of the foregoing systems, wherein the first wake period is defined by a timeout interval, and wherein the first sleep period is defined by the timeout interval subtracted from a wake interval, and wherein the sleep/wake schedule includes the timeout interval and the wake interval.
A node includes a power source, a timer, and a controller. The controller receives a wake/sleep schedule from an external source and is configured to wake the node and listen for external commands while the node is in a wake state, and power down the node while the node is in a sleep state. The node remains in the wake state for a wake period and remains in the sleep state for a sleep period.
The node of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing node, wherein the sleep period is greater than the wake period.
A further embodiment of any of the foregoing nodes, wherein the power source is a battery or energy harvester.
A further embodiment of any of the foregoing nodes, wherein the wake/sleep schedule is received from an external network controller.
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
