Time-division physical layer access for network communications

Abstract

A system is provided in which different communication modes are switched by a network node according to a time division schedule to transmit and receive data packets. For example, a transmitting node is configured to determine a scheduled communication mode for a next time division according to the time division schedule and transmit a data packet in that time division when the scheduled communication mode matches a selected communication mode supported by both the transmitting node and the receiving node. A receiving node operates in the scheduled communication mode specified for a current time division by the time division schedule and determines whether a header of a data packet is detected in the current time division. If not, the receiving node switches to a second scheduled communication mode specified for a subsequent time division by the time division schedule to detect a header of a data packet in the subsequent time division.

Description

[Technical Field]

[0001] The present disclosure relates generally to communication between nodes in a network, and more particularly to switching between different communication modes according to a time-sharing schedule by transmitting and receiving nodes supporting multiple physical (PHY) layer configurations in the network to transmit and receive data packets over the network. [Background technology]

[0002] In a network, infrastructure nodes (or simply "nodes") such as endpoint devices, gateways, or routers constantly communicate with one another, for example, to exchange messages or transmit data. However, different nodes may have different hardware and software configurations and support different communication modes. Furthermore, each node may support multiple communication modes. A communication mode may indicate a specific data rate for data transmission, a specific coding scheme, a specific modulation scheme, or a combination thereof. For example, some nodes may be configured to support a specific communication mode of orthogonal frequency division multiplexing ("OFDM"), while other nodes may be configured to support a different OFDM communication mode. Also, some nodes may be configured to support various communication modes based on frequency shift keying ("FSK") instead of or in addition to OFDM. When transmitting data, a transmitting node can select a communication mode from among multiple supported communication modes to reliably and efficiently transmit data to a receiving node. Summary of the Invention [Problem to be solved by the invention]

[0003] In order for a receiving node to correctly receive and decode the received data, it must identify the communication mode used to transmit the data and switch to the correct communication mode. One current mode switching mechanism relies on a mode switch header that is prepended to a data packet to indicate the mode used by the transmitting node. Because the mode switch header is usually communicated in the base mode, which has a low data rate, transmitting the mode switch header can significantly reduce transmission efficiency, especially in communication modes with high data rates. [Means for solving the problem]

[0004] Aspects and embodiments are disclosed relating to an apparatus and process for a network node to transmit and receive data packets by switching between different communication modes according to a time division schedule. In one embodiment, a system includes a transmitting node and a receiving node. The transmitting node is configured to determine a scheduled communication mode for a next time division according to the time division schedule. The time division schedule includes a plurality of cycles, each cycle including at least two time divisions and specifying a scheduled communication mode for each of the at least two time divisions. The transmitting node is further configured to determine that the scheduled communication mode for the next time division corresponds to a selected communication mode from a plurality of communication modes supported by both the transmitting node and the receiving node. The selected communication mode is determined based on communication conditions of the transmitting node and the receiving node. The transmitting node is also configured to generate and transmit a data packet to the receiving node using the scheduled communication mode in response to determining that the next time division has arrived and become the current time division. The receiving node is configured to operate in a scheduled communication mode designated for a current time division according to the time division schedule, determine while operating in the scheduled communication mode that a preamble of the data packet has been detected in the current time division, and receive and process a remaining portion of the data packet in the scheduled communication mode in response to determining that the preamble of the data packet has been detected.

[0005] In another embodiment, a node of a network includes a processor configured to execute computer-readable instructions and a memory configured to store computer-readable instructions that, when executed by the processor, cause the processor to perform operations, including operating in a first scheduled communication mode designated for a current time division by a time division schedule. The time division schedule includes a plurality of cycles, each cycle including at least two time divisions, and designating a respective scheduled communication mode for the at least two time divisions. The first scheduled communication mode is one of a plurality of supported communication modes of the node. The operations further include, while operating in the first scheduled communication mode, determining whether a signal for a data packet transmitted by the transmitting node is detected in the current time division, receiving a remainder of the data packet in the first scheduled communication mode in response to determining that the signal for the data packet has been detected, and switching to a second scheduled communication mode designated for a subsequent time division by the time division schedule to receive the data packet in response to determining that the data packet has not been received during the current time division. The second scheduled communication mode is different from the first scheduled communication mode.

[0006] In yet another embodiment, a method includes, by a node of a network, determining a scheduled communication mode for a next time division according to a time division schedule, the time division schedule including a plurality of cycles, each cycle including at least two time divisions and specifying respective scheduled communication modes for the at least two time divisions. The method further includes determining, by the node, that the scheduled communication mode for the next time division corresponds to a communication mode selected from a plurality of communication modes supported by both the node and a receiving node. The selected communication mode is determined based on communication conditions of the node and the receiving node. The method further includes, in response to determining that the next time division has arrived and become the current time division, generating and transmitting, by the node, a data packet over the network to the receiving node using the scheduled communication mode.

[0007] These exemplary aspects and features are mentioned not to limit or define the presently described subject matter, but to provide examples to aid in understanding the concepts described herein. Other aspects, advantages, and features of the presently described subject matter will become apparent after reviewing the entire application. [Brief explanation of the drawings]

[0008] These and other features, aspects, and advantages of the present disclosure will become better understood from the following detailed description when taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a block diagram illustrating an example operating environment for switching between different communication modes according to a time-sharing schedule for transmitting and receiving data packets, according to an aspect of the present disclosure. [Figure 2] FIG. 2 illustrates aspects of a transmitting node and a receiving node configured to switch between different communication modes according to a time-sharing schedule to transmit and receive data packets, respectively, according to an aspect of the present disclosure. [Figure 3]FIG. 3 is an example of a time-sharing schedule followed by nodes in a network to send and receive data packets, according to some embodiments of the present disclosure. [Figure 4A] FIG. 4A is a diagram illustrating an example of a data packet received at a receiving node, the communication mode of the receiving node, and the actions performed by the receiving node according to a prior art mode switching mechanism. [Figure 4B] FIG. 4B illustrates an example of a data packet received at a receiving node, a communication mode of the receiving node, and an operation performed by the receiving node based on a time-sharing schedule according to an aspect of the present disclosure. [Figure 4C] FIG. 4C illustrates an example of a data packet received at a receiving node, a communication mode of the receiving node, and an operation performed by the receiving node when the communication mode specified by the time-sharing schedule does not match the selected communication mode, according to an aspect of the present disclosure. [Figure 5] FIG. 5 is an example of a process for receiving and processing data packets transmitted by a transmitting node according to an aspect of the present disclosure. [Figure 6] FIG. 6 is an example of a process for transmitting data packets according to a time-sharing schedule in accordance with certain aspects of the present disclosure. [Figure 7] FIG. 7 is a block diagram illustrating an example of a suitable computing system for implementing aspects of the techniques and technologies presented herein. DETAILED DESCRIPTION OF THE INVENTION

[0009] A system and method are provided for network nodes to switch between different communication modes according to a time division schedule to transmit and receive data packets. Both the transmitting node and the receiving node switch between different communication modes according to the time division schedule. The time division schedule includes multiple cycles, each cycle including at least two time divisions indicating the communication mode of the corresponding time division. By following the time division schedule, the transmitting node and the receiving node operate in the same communication mode at a given time. In this way, the communication modes of the transmitting node and the receiving node match, eliminating the need to add a mode switch header indicating the communication mode when transmitting a data packet.

[0010] For example, a transmitting node selects a communication mode from a set of supported communication modes and generates a data packet using the selected communication mode. Instead of inserting a mode switch header into the data packet to indicate the selected communication mode, the transmitting node transmits the data packet directly using the selected communication mode if the selected communication mode matches the communication mode indicated by the current time division. If the selected communication mode does not match the communication mode indicated by the current time division, the transmitting node waits until a time division in which the communication mode matches the selected communication mode and transmits the data packet to the receiving node.

[0011] A receiving node operating in a communication mode according to a time division schedule listens for traffic on the network. If the receiving node does not detect a data packet preamble and header in the current time division, it switches to the next communication mode specified by the time division schedule for the next time division and listens for traffic in this new communication mode. If the receiving node detects a data packet preamble and header in the current time division, the receiving node continues receiving and processing the data packet. In some examples, at least one of the time divisions has its communication mode set to a base communication mode, which is the mode with the longest communication range among a set of supported communication modes. One or more other time divisions can have communication modes with higher data rates. In this way, the receiving node can detect traffic with the longest communication range for a period of each cycle and receive data at a higher data rate for the remainder of the cycle.

[0012] The techniques described in this disclosure increase the efficiency of communication between nodes in a network. As mentioned above, the mode switch header used in existing approaches may take longer to transmit than the payload due to the low data rate of the base mode used to communicate the mode switch header. In contrast, the time-division mode switch mechanism described in this disclosure allows data packets to be transmitted without using a mode switch header. As a result, transmission efficiency (e.g., the ratio of effective data rate to payload data rate) can be significantly improved.

[0013] Furthermore, the time division mode switching mechanism described in this disclosure allows the receiving node to operate in the base mode, which has the longest communication range, for at least a portion of each cycle. This allows the receiving node to communicate with transmitting nodes that are farther away, maximizing the communication range of the node. For the remainder of each cycle, the node can be configured to operate at a much higher bit rate than in the base mode, further improving communication efficiency.

[0014] 1 illustrates an example network 100 in which nodes switch between different communication modes according to a time-sharing schedule to transmit and receive data packets according to certain aspects of the present disclosure. The network 100 illustrated in FIG. 1 includes multiple nodes 112A-112H (sometimes referred to herein individually and collectively as nodes 112). The network 100 may be a radio frequency (RF) mesh network (such as an IEEE 802.15.4 network), a Wi-Fi network, a cellular network, Ethernet, a power line carrier network, or any other wired or wireless network. Correspondingly, the nodes 112 may be RF radios, computers, mobile devices, power line network devices, or other types of devices capable of directly communicating with other devices on the network 100.

[0015] In examples where network 100 is a mesh network, nodes 112 may include measurement nodes for collecting data from their respective deployed locations, processing nodes for processing data available to the nodes, router nodes for forwarding data received from one node to another node in network 100, or nodes configured to perform a combination of these functions. Nodes 112 are further configured to communicate with each other such that messages or data can be exchanged between nodes 112.

[0016] In one example, network 100 is associated with a resource distribution network, such as a utility network, and is capable of distributing measurement data obtained in the resource distribution network. In this example, nodes 112, which may include meters such as electricity meters, gas meters, water meters, steam meters, etc., are implemented to measure various operating characteristics of the resource distribution network and transmit the collected data over network 100, for example, to root nodes 114A and 114B (which may be individually referred to herein as root nodes 114 and collectively referred to herein as root nodes 114).

[0017] The root node 114 of the network 100 may be configured to communicate with the nodes 112 to perform operations such as managing the nodes 112, collecting data from the nodes 112, and forwarding the data to the head-end system 104. The root node 114 may also be configured to function as a data measuring and processing node itself. The root node 114 may be a personal area network (PAN) coordinator, gateway, or any other device capable of communicating with the head-end system 104. The root node 114 ultimately transmits the generated and collected data to the head-end system 104 via one or more additional networks (not shown in FIG. 1 ). The head-end system 104 may function as a central processing system that receives streams of data or messages from the root node 114. The head-end system 104 may process the collected data or have the collected data processed for various applications.

[0018] In order for the nodes of network 100 to communicate with each other, each node is configured to support one or more communication modes. For example, node 112 may be configured to support FSK at various data rates. Another node may be configured to support both FSK and OFDM at different modulation and coding scheme (MCS) levels. Because different nodes of network 100, including node 112 and root node 114, may be configured differently, their ability to support communication modes may vary. Thus, each node in the network is configured with a common basic communication mode.

[0019] In some examples, the base mode is determined by the capabilities of the deployment. For example, a node deployment may include older, less capable nodes alongside newer, more capable nodes. In this case, the network's base mode may be a mode that the older nodes can support, such as FSK modulation. New OFDM-capable nodes may use the FSK-based mode for multicast messages and initiate mode-switching operations. Furthermore, in this deployment, a node may assume it has the minimum capabilities required to join the network and support the base node until it receives positive confirmation from that node that it has the enhanced capabilities. In one example, this information may be shared using information elements defined in the IEEE 802.15.4 standard. In a further example, the base mode of node 112 may be selected as the mode among its supported communication modes that has a longer communication range than the majority of the supported communication modes, e.g., the mode with the longest communication range.

[0020] For a pair of nodes to communicate with each other, the node transmitting data, also referred to herein as the "transmitting node," determines a communication mode so that data packet 122A, 122B, ..., or 122H is successfully transmitted to the other node, also referred to herein as the "receiving node." Data packets 122A-122H may be individually or collectively referred to herein as data packets 122. According to some aspects of the present disclosure, the selected communication mode may also be used by the receiving node to successfully transmit an acknowledgment packet back to the transmitting node to confirm that the receiving node has received the data packet 122. In some examples, the receiving nodes are diversity receivers, each supporting multiple physical layer configurations. To successfully receive and process data packet 122, the transmitting node and receiving node switch between the multiple supported communication modes according to the same time-division schedule. As a result, the transmitting node and receiving node can communicate directly using the communication mode specified for the corresponding time division when the transmission occurs. Additional details regarding transmitting and receiving data packets using a time-shared scheduled communication mode are provided below with respect to FIGS.

[0021] It should be understood that communication of data packets based on the time-sharing schedule described herein may be utilized by any node of network 100, including node 112, root node 114, or any other node of network 100 that is capable of communicating with other nodes in the network. Additionally, while Figure 1 depicts a particular network topology (e.g., a DODAG tree), other network topologies are possible (e.g., a ring topology, a mesh topology, a star topology, etc.).

[0022] 2, which illustrates aspects of a transmitting node and a receiving node configured to transmit and receive data packets based on a time-sharing schedule in accordance with a carrier sense multiple access (CSMA) protocol, according to an aspect of the present disclosure. In the example shown in FIG. 1, the transmitting node 202 may be node 112, root node 114, or any other node in network 100 that can communicate with another node in the network. The receiving node 212 is a neighbor of the transmitting node 202, i.e., any node in network 100 with which the transmitting node 202 can communicate directly.

[0023] The transmitting node 202 may include a mode selection module 204 configured to select a communication mode such that the transmitting node 202 can successfully complete communication with the receiving node 212 using the selected communication mode. In some examples, the transmitting node 202 determines the communication mode based on communication conditions of the transmitting node 202 and the receiving node 212. The communication conditions may be described using various factors, including, but not limited to, the transmit power used to transmit the data packet 122, the path loss between the transmitting node 202 and the receiving node 212 (i.e., the power attenuation as the transmitted signal propagates through the communication path), the SNR requirement at the receiving node 212, the noise floor observed at the receiving node 212, etc.

[0024] The transmitting node 202 further includes a data packet generation module 206 configured to generate a data packet 122 using the selected communication mode for communication with the receiving node 212. The data packet 122 generated by the data packet generation module 206 may include a preamble and synchronization data 222, a header 224, and payload data 226. The preamble and synchronization data 222 includes a preamble signal followed by synchronization data that may be utilized by the receiving node 212 for purposes such as synchronization. The header 224 may include data such as a data packet delimiter, a physical layer header describing the length of the data unit, etc. The payload data 226 includes the actual intended message.

[0025] To transmit data packets 122, the transmitting node 202 and the receiving node 212 follow a time division schedule 214 for the communication modes of the nodes 112 in the network 100. FIG. 3 shows an example of the time division schedule 214. The time division schedule 214 includes multiple time divisions, each of which specifies a communication mode, also referred to herein as a "scheduled communication mode," for the node 112. For example, during the first time division 302A (i.e., time 0 to 3 ms), the node 112 in the network 100 uses communication mode 2-FSK 10 kbps. During the next time division 302B (i.e., time 3 to 5.5 ms), the node 112 in the network 100 uses communication mode OFDM Option 1, which supports data rates from 100 kbps to 2.4 Mbps. During the third time division 302C (i.e., time 5.5 to 8.5 ms), the communication mode switches to 2-FSK 10 kbps. The same pattern repeats for the next time division. It should be understood that 2-FSK and OFDM Option 1 are used as examples of communication modes that may be included in the time division schedule 214 and should not be construed as limiting. Other communication modes, such as IEEE 802.15.4 SUN O-QPSK, may also be employed.

[0026] As can be seen from the example shown in FIG. 3, the time division schedule 214 has multiple cycles, each cycle including two or more time divisions. In each cycle, the node 112 operates in a different communication mode in a different time division. The duration of the time divisions within a cycle may be the same or different. In some examples, the duration of a time division is determined based on the communication mode specified for that time division. For example, the duration of a time division may be determined to be at least the sum of the time it takes for the receiving node 212 to finish receiving the preamble, synchronization data, and header, the time it takes for the receiving node 212 to set the communication mode, and the maximum time synchronization error.

[0027] According to this method, the duration of time division 1 shown in FIG. 3 can be determined as follows: If the time to receive the preamble using 2-FSK 10 kbps is 1.6 ms, the time to set up the 2-FSK 10 kbps mode by the receiving node 212 is 0.36 ms, and the maximum time synchronization error is 1 ms, then the duration of time division 1 is at least 1.6 + 0.36 + 1 ≈ 3 ms. Similarly, for time division 2, the time to receive the preamble, synchronization data, and header using OFDM option 1 is 1.08 ms, the time to set up the OFDM mode by the receiving node 212 is 0.29 ms, and the maximum time synchronization error is again 1 ms, then the duration of time division 2 is at least 1.08 + 0.29 + 1 ≈ 2.5 ms. Although time division schedule 214 indicates that the time division durations are their respective minimum time durations, each time division can have a duration longer than its respective minimum time duration.

[0028] 2, the transmitting node 202 transmits the generated data packet 122 to the receiving node 212 using the communication mode of the current time division. If the communication mode of the current time division does not match the selected communication mode determined by the mode selection module 204, the transmitting node 202 may, for example, wait until a future time division in which the communication mode matches the selected communication mode. For example, if the communication mode selected by the mode selection module is OFDM Option 1 and the communication mode of the current time division is 2-FSK 10 kbps, the transmitting node 202 may wait until the next time division in which the communication mode is OFDM Option 1 and begin transmitting the data packet 122 in that communication mode.

[0029] As previously described, the receiving node 212 also switches communication modes according to the time division schedule 214. At a given point in time, the receiving node 212 operates in the communication mode of the current time division and listens for traffic in the network 100. If the receiving node 212 does not detect the preamble and synchronization data 222 and header 224 of the data packet 122 in the current time division, the receiving node 212 switches to the communication mode of the next time division and continues listening for traffic on the network 100. If the receiving node 212 detects the preamble and synchronization data 222 and header 224 of the data packet 122 in the current time division, the receiving node 212 continues to receive the remainder of the data packet 122, including the payload data 226, using the current communication mode. After the receiving node 212 finishes receiving the data packet 122, it determines the current time division based on the time division schedule 214 and switches to the communication mode specified in the current time division to listen for network traffic.

[0030] 4A and 4B, a comparison is made between the standard IEEE 802.15.4 mode switch mechanism and the time-sharing mode switch mechanism described herein. FIG. 4A illustrates an example of data received at a receiving node, the mode of the receiving node, and operations performed by the receiving node at different time periods in accordance with the standard IEEE 802.15.4 mode switch communication mechanism. FIG. 4B illustrates the data received at the receiving node, the mode of the receiving node, and operations performed by the receiving node based on the time-sharing schedule in accordance with certain aspects of the present disclosure.

[0031] The standard IEEE 802.15.4 mode switch mechanism shown in Figure 4A communicates the communication mode selected by the transmitting node using a mode switch header added to each data packet. Therefore, during the overhead period T0 during which the communication mode is detected, a receiving node using the standard IEEE 802.15.4 mode switch mechanism operates in base mode to receive the mode switch header and then processes the mode switch header to determine the communication mode used by the transmitting node. Once the communication mode is determined, the receiving node switches to the determined communication mode and receives and processes the preamble and synchronization data, header, and remaining data in the data packet. After this communication, the receiving node returns to base mode.

[0032] In comparison, in the time-division mode switching mechanism presented herein, the receiving node 212 operates on the same time-division schedule 214 as the transmitting node 202, so the communication modes of the receiving node 212 and the transmitting node 202 are synchronized (ignoring synchronization errors between the receiving node 212 and the transmitting node 202). Therefore, when the transmitting node 202 transmits a data packet 122, the communication modes of the transmitting node 202 and the receiving node 212 are the same. This allows the receiving node 212 to directly receive the data packet 122 without having to predetermine the communication mode of the data packet 122. This eliminates the overhead period T0 in the standard IEEE 802.15.4 mode switch mechanism. As a result, the technique proposed herein can significantly improve communication efficiency.

[0033] However, there may be cases where the communication mode selected by the transmitting node 202 does not match any of the communication modes specified in the time division schedule 214. For example, the selected communication mode may be 2-FSK 100 kbps, which differs from all of the communication modes specified in the time division schedule 214 of FIG. 3 . In that case, the transmitting node 202 may use the mode switch header mechanism to notify the receiving node 212 of the selected communication mode. Specifically, the transmitting node 202 may generate and transmit a mode switch header indicating the selected communication mode while operating in the communication mode specified in the time division schedule 214 of the current time division, such as the 2-FSK 10 kbps mode. The transmitting node 202 may then switch to the selected communication mode and transmit the remainder of the data packet 122 in the selected communication mode.

[0034] While operating in its current time-sharing scheduled communication mode, the receiving node 212 can receive the mode switch header and determine the selected communication mode of the data packet 122. Once the selected communication mode is determined, the receiving node 212 can switch to the selected communication mode and receive and process the data packet 122. This scenario is illustrated in FIG. 4C. The communication efficiency of the scenario in FIG. 4C is similar to that of the standard IEEE 802.15.4 mode switch mechanism illustrated in FIG. 4A, but this scenario occurs only when the communication mode selected by the transmitting node 202 does not match the communication mode specified in the time-sharing schedule 214. Therefore, the overall communication efficiency of the proposed technique is still much higher than that of the standard IEEE 802.15.4 mode switch mechanism.

[0035] 5 is an example process 500 by which a receiving node receives and processes data packets according to certain aspects of the disclosure. One or more nodes of network 100 (e.g., node 112 or root node 114) implement the operations shown in FIG. 5 by executing appropriate program code when acting as a receiving node. For purposes of explanation, process 500 is described with reference to the specific example shown in the figure. However, other implementations are possible.

[0036] At block 502, the process 500 includes the receiving node 212 listening for incoming traffic in a scheduled communication mode of a current time division (for division index i) according to the time division schedule 214. At block 504, the process 500 includes the receiving node 212 determining whether a packet signal is detected. Depending on the communication mode, the receiving node 212 can determine that a signal is detected based on detecting a preamble, synchronization data, and / or a header. For example, if the current scheduled communication mode is an FSK mode, the receiving node 212 can determine that a signal is detected when a preamble of a data packet is detected. If the current scheduled communication mode is an OFDM mode, the receiving node 212 can determine that a signal is detected when a preamble, synchronization data, and a header of a data packet are detected. In another example, if the current scheduled communication mode is an OFDM mode, the receiving node 212 can determine that a signal is detected if a preamble or synchronization data of a data packet is detected. If the receiving node 212 determines that a packet signal is not detected, the process 500 proceeds to block 506 and determines whether the current time division i has expired. If not, the transmitting node 202 continues to listen for incoming traffic in a scheduled communication mode. If, at block 506, the receiving node 212 determines that the current time division has expired, the process 500 includes switching to the scheduled communication mode for the next time division and incrementing the time division index i by 1. The receiving node 212 then continues to listen for incoming traffic using the new scheduled communication mode.

[0037] If, at block 504, the receiving node 212 determines that a packet signal has been detected, the process 500 proceeds to block 510. At block 510, the receiving node 212 continues to receive the remainder of the data packet 122 in the current scheduled communication mode. This reception process may span multiple time divisions. At block 512, the process 500 includes the receiving node 212 determining whether data reception is complete. If not, the receiving node 212 continues to receive the data packet 122 at block 510. If reception is complete, the process 500 includes the receiving node 212 determining the current time division according to the time division schedule 214 at block 514 and setting the time division index i accordingly. In the process 500, the receiving node 212 switches to the scheduled communication mode of the current time division at block 516 and listens for incoming traffic using that mode at block 502.

[0038] Turning now to Figure 6, an example process 600 for transmitting data packets according to a time-sharing schedule is shown. One or more nodes of network 100 (e.g., node 112 or root node 114) implement the operations shown in Figure 6 by executing appropriate program code when operating as a transmitting node. For illustrative purposes, process 600 is described with reference to the specific example shown in the figure. However, other implementations are possible.

[0039] At block 601, process 600 includes the sending node 202 receiving a data transmission request. At block 602, process 600 includes the sending node 202 determining an upcoming time division based on the time division schedule 214. At block 604, process 600 includes the sending node 202 determining whether the scheduled communication mode of the next time division matches the selected communication mode of the data packet 122. As described in detail with respect to FIG. 2, the sending node 202 can determine the transmission mode of the data packet 122 using the mode selection module 204 based on the communication status of the sending node 202 and the receiving node 212. If the scheduled communication mode does not match the selected communication mode, the sending node 202 waits for the next time division at block 612 and repeats the operation of block 602 to determine the scheduled communication mode for the next time division.

[0040] If, at block 604, the transmitting node 202 determines that the scheduled next communication mode matches the selected communication mode, then, at block 606, the process 600 includes the transmitting node 202 performing pre-transmission operations. These operations may include, for example, performing a clear channel assessment (CCA) to determine whether the channel is available for transmission. The pre-transmission operations may also include other operations that the transmitting node 202 must perform before beginning transmission of data packets. At block 608, the process 600 includes transmitting data using the scheduled communication mode when the next time division arrives (i.e., when the time to enter the next time division arrives). The transmission may include setting up transmission using the scheduled communication mode and waiting a maximum time synchronization error period. The nodes 112 in the network 100 synchronize their clocks from time to time. However, synchronization errors may occur, causing the clocks of the nodes 112 to have a certain offset from each other. The maximum time synchronization error period represents the maximum time of synchronization error between the nodes 112. Waiting the maximum time synchronization error period ensures that the receiving node 212 is in the correct communication mode when transmitting the data packet 122, even if there is a synchronization error between the transmitting node 202 and the receiving node 212. The transmitting node 202 then transmits the data packet 122 in the current time-division scheduled communication mode.

[0041] 6, if the scheduled communication mode does not match the selected communication mode, the transmitting node 202 waits for the next time division, but in other examples, the transmitting node 202 may transmit using the scheduled communication mode even if it does not match the selected communication mode. For example, if both the transmitting node and the receiving node support the scheduled communication mode, the transmitting node may choose to transmit in the next time division (if it is fast to execute) rather than waiting for the next matching time division, thereby avoiding waiting times.

[0042] 6 may be employed if the selected communication mode matches at least one scheduled communication mode in time sharing schedule 214. If the selected communication mode does not match any of the scheduled communication modes in time sharing schedule 214, transmitting node 202 may indicate the selected communication mode using a switch header as described above.

[0043] It should be understood that the time division schedule 214 illustrated in FIG. 3 is for illustrative purposes only and should not be construed as limiting. Various other methods for constructing the time division schedule 214 are available. For example, the time division schedule 214 can have multiple time divisions within a cycle. At least one communication mode in the time division schedule 214 can be set to a base mode or another long-range, low-data-rate mode. At least one communication mode in the time division schedule 214 can be set to the communication mode with the highest data rate. In some implementations, the communication modes included in the time division schedule 214 can be determined based on the communication modes used by the nodes 112 in the network 100. For example, the time division schedule 214 can be configured to include a communication mode that the node 112 has frequently used based on past communications. Furthermore, the time division mode switching mechanism illustrated herein can be implemented using other MAC protocols, such as the CSMA media access control (MAC) protocol or the time-synchronized channel hopping (TSCH) protocol.

[0044] In some scenarios, not all nodes 112 on network 100 implement the time division mode switch mechanism described herein. In these scenarios, nodes 112 that do not implement the time division mode switching mechanism (also referred to as non-compliant nodes) may not be aware of the time division schedule 214 and instead rely on the mode switch header to communicate the selected communication mode to receiving nodes in network 100. This includes scenarios where nodes that implement the time division mode switching mechanism (also referred to as compliant nodes) first join the network and have not yet obtained the time division schedule 214. To allow compliant nodes 112 to communicate with non-compliant nodes, the preamble of data packet 122 may be increased in length to include a full preamble detection period, regardless of where the receiving compliant node is operating within the cycle of time division schedule 214 when the preamble is being transmitted. For example, the duration of the preamble may be determined to be at least a cycle of time division schedule 214 plus a period for detecting the preamble of a base mode data packet. In this manner, when a compliant node receives a data packet 122 from a non-compliant node, it can detect the preamble, i.e., mode switch header, and determine the selected communication mode of the data packet 122. In another example, the length of the preamble can be set to be close to but short of one cycle of the time sharing schedule 214, such as 90%. This setting can be used in conjunction with a retry mechanism in the communication protocol to allow the receiving node to receive the preamble and determine the correct communication mode.

[0045] Example Node

[0046] 7 illustrates an example node 700 that can be used to implement the mode switch mechanisms described herein, such as node 112 or root node 114. Node 700 may include a processor 702, a memory 704, and a transceiver device 720, each communicatively coupled via a bus 710. The components of node 700 may be powered from an A / C power source or a low-energy source such as a battery (not shown). Transceiver device 720 may include (or be communicatively coupled to) an antenna 708 for communicating with other nodes. In some examples, the transceiver device is a radio frequency (“RF”) transceiver for transmitting and receiving signals wirelessly.

[0047] The processor may include a microprocessor, an application-specific integrated circuit ("ASIC"), a state machine, a field-programmable gate array ("FPGA"), or other suitable computing device. The processor may include any number of computing devices and may be communicatively coupled to a computer-readable medium, such as memory 704. The processor 702 may execute computer-executable program instructions or access information stored in memory to perform operations, such as the time-sharing schedule 214, described herein. The instructions may include processor-specific instructions generated by a compiler and / or interpreter from code written in any suitable computer programming language. When executed, the instructions may configure the node 700 to perform any of the operations described herein. While the processor, memory, bus, and transceiver unit are depicted in FIG. 7 as separate components communicating with each other, other implementations are possible. The systems and components described herein are not limited to any particular hardware architecture or configuration.

[0048] General considerations

[0049] Numerous specific details are described herein to provide a thorough understanding of the subject matter of the present invention. However, those skilled in the art will understand that the subject matter of the present invention may be practiced without these specific details. In other instances, methods, devices, or systems that would be known to one of ordinary skill in the art have not been described in detail so as not to obscure the subject matter of the present invention.

[0050] The functionality described herein is not limited to a particular hardware architecture or configuration. A computing device can include any suitable arrangement of components that provide a result conditioned on one or more inputs. Suitable computing devices range from general-purpose computing devices to specialized computing devices that implement one or more aspects of the present subject matter, and include general-purpose microprocessor-based computer systems that access stored software (i.e., computer-readable instructions stored in the computer system's memory) that programs or configures the computing system. Any suitable programming, scripting, or other type of language or combination of languages ​​can be used to implement the teachings contained herein in software used to program or configure a computing device.

[0051] Aspects of the methods disclosed herein may be performed in operation of such a computing device. The order of the blocks shown in the above examples may be varied in various ways. For example, blocks may be rearranged, combined, or divided into sub-blocks. Certain blocks or processes may be performed in parallel.

[0052] The use of "adapted to" or "configured" herein is meant to be open and inclusive language that does not preclude devices adapted or configured to perform additional tasks or steps. Additionally, the use of "based on" is meant to be open and inclusive, such that when a process, step, calculation, or other action is "based on" one or more recited conditions or values, it may in fact be based on additional conditions or values ​​beyond the recited conditions or values. Headings, lists, and numbering provided herein are for ease of description and are not limiting.

[0053] While the gist of the present invention has been described in detail with respect to specific embodiments thereof, it is recognized that those skilled in the art, upon gaining an understanding of the foregoing, can readily make modifications, variations, and equivalents to such embodiments. Accordingly, it should be understood that the present disclosure has been presented for purposes of illustration and not limitation, and is not intended to preclude the inclusion of modifications, variations, and / or additions to the gist of the present invention as would be readily apparent to one skilled in the art.

Claims

1. A system including a sending node and a receiving node, The sending node determining a scheduled communication mode for a next time division according to a time division schedule, the time division schedule including a plurality of cycles, each cycle including at least two time divisions, and specifying a scheduled communication mode for each of the at least two time divisions; determining that a selected communication mode from among a plurality of communication modes supported by both the transmitting node and the receiving node, determined based on communication statuses of the transmitting node and the receiving node, matches a scheduled communication mode for the next time division; In response to determining that the next time division has arrived and become the current time division, generating and transmitting a data packet to the receiving node using the scheduled communication mode; and The receiving node operating in a scheduled communication mode designated for the current time division according to the time division schedule; determining, while operating in a scheduled communication mode, that a preamble of a data packet has been detected in a current time division; receiving and processing a remainder of the data packet in a scheduled communication mode based at least in part on determining that the preamble of the data packet has been detected; configured to: system.

2. The receiving node further determining that no data packets have been received during a predetermined time division; switching to a second scheduled communication mode specified for a subsequent time division by the time division schedule and detecting a data packet in the subsequent time division, the second scheduled communication mode being different from the first scheduled communication mode; and configured to: The system of claim 1 .

3. Sending a data packet to a receiving node waiting a time determined according to a maximum time synchronization error period and transmitting the data packet to the receiving node; The system of claim 1 , comprising:

4. Before sending a data packet to the receiving node, The sending node: To perform Clear Channel Assessment (CCA) It is further composed of The system of claim 1 .

5. One of the scheduled communication modes is the base mode of the receiving node; 2. The system of claim 1, wherein the base mode includes one of a plurality of supported communication modes that has a longer communication range than a majority of a plurality of supported communication modes.

6. The sending node: determining that the selected communication mode is different from a scheduled communication mode of a time-sharing schedule; generating and transmitting a mode switch header in the current time division scheduled communication mode to indicate the selected communication mode; transmitting a data packet in the selected communication mode; To do The system of claim 1 further comprising:

7. The receiving node: detecting a mode switch header while operating in the scheduled communication mode to determine the selected communication mode; switching to the selected communication mode; receiving and processing data packets in the selected communication mode; To do The system of claim 6 further comprising:

8. 10. The system of claim 1, wherein the multiple supported communication modes include one or more frequency shift keying (FSK) communication modes or one or more orthogonal frequency division multiplexing (OFDM) communication modes.

9. A node of the network, a processor configured to execute computer-readable instructions; a memory configured to store computer-readable instructions; Including, The computer readable instructions stored in the memory include: operating in a first scheduled communication mode designated for a current time division by a time division schedule, the time division schedule including a plurality of cycles, each cycle including at least two time divisions, and designating a respective scheduled communication mode for the at least two time divisions, the first scheduled communication mode being one of a plurality of supported communication modes of the node; determining whether a signal of a data packet transmitted by a transmitting node is detected in a current time division while operating in the first scheduled communication mode; receiving a remaining portion of the data packet in the first scheduled communication mode in response to determining that a signal of the data packet has been detected; In response to determining that no data packets have been received during the current time division, switching to a second scheduled communication mode designated for a subsequent time division by the time division schedule to receive the data packets, the second scheduled communication mode being different from the first scheduled communication mode; detecting a mode switch header in a data packet while operating in the first scheduled communication mode to determine a selected communication mode; switching to the selected communication mode; receiving and processing a data packet in a selected communication mode, wherein the data packet is to be transmitted by a transmitting node in response to determining that the selected communication mode is different from any scheduled communication mode in a time sharing schedule; causing the processor to perform operations including: A node in a network.

10. The data packet 10. The node of claim 9, wherein the data packet is transmitted by the transmitting node based on a communication mode selected for the data packet that matches the first scheduled communication mode specified for the current time division by a time division schedule.

11. one of the scheduled communication modes is a base mode of the node; 10. The node of claim 9, wherein the base mode comprises one of a plurality of supported communication modes that has a longer communication range than a majority of a plurality of supported communication modes.

12. Determining that a signal of a data packet has been detected includes determining that a preamble of the data packet has been detected, or determining that both a preamble and a header of the data packet have been detected. The node of claim 9.

13. 10. The node of claim 9, wherein the multiple supported communication modes include one or more frequency shift keying (FSK) communication modes or one or more orthogonal frequency division multiplexing (OFDM) communication modes.

14. determining, by a node of the network, a scheduled communication mode for a next time division according to a time division schedule, the time division schedule including a plurality of cycles, each cycle including at least two time divisions, and specifying respective scheduled communication modes for the at least two time divisions; determining, by the node, that the scheduled communication mode for the next time division corresponds to a communication mode selected from a plurality of communication modes supported by both the node and a receiving node, the selected communication mode being determined based on communication conditions between the node and the receiving node; generating and transmitting, by the node, a data packet to a receiving node over the network using the scheduled communication mode in response to determining that the next time division has arrived and become the current time division; A method comprising:

15. transmitting a data packet to the receiving node, 15. The method of claim 14, comprising waiting a time determined according to a maximum time synchronization error period and transmitting the data packet to the receiving node.

16. 15. The method of claim 14, further comprising performing a clear channel assessment (CCA) before transmitting the data packet to the receiving node.

17. one of the scheduled communication modes is a base mode of the receiving node; 15. The method of claim 14, wherein the base mode includes one of a plurality of supported communication modes that has a longer communication range than a majority of a plurality of supported communication modes.

18. determining that a selected communication mode is different from the scheduled communication mode of a time-sharing schedule; generating and transmitting a mode switch header in said scheduled communication mode of the current time division to indicate a selected communication mode; transmitting a data packet in a selected communication mode; The method of claim 14 further comprising:

19. 15. The method of claim 14, wherein the multiple supported communication modes include one or more frequency shift keying (FSK) communication modes or one or more orthogonal frequency division multiplexing (OFDM) communication modes.

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