TW202450357A - Computer-executed method and network device - Google Patents

Abstract

A computer-executed method is provided for IEEE 802.15.4 devices based on a suspendable carrier-sense multiple access with collision avoidance (CSMA/CA) control program and standard CSMA/CA control program for an IEEE 802.15.4 network composing of IEEE 802.15.4 devices. The computer-executed method is provided on an IEEE 802.15.4 device, and causes a processor of the IEEE 802.15.4 device to perform steps that include determining the permission of backoff suspension and the intention of IEEE 802.15.4 device to perform backoff suspension, selecting the suspendable CSMA/CA control program if the backoff suspension is permitted and IEEE 802.15.4 device intends to perform backoff suspension. The suspendable CSMA/CA control program is configured to perform active CCA within each unit backoff period and suspend backoff if channel is detected to be busy, performing a CCA when backoff completes, transmitting frame when the detected channel status is an idle state or incrementing a number of backoff (NB) when the detected channel status is an busy state, determining if a NB exceeds the macMaxCSMABackoffs, incrementing a number of retransmissions (NR) when a NB exceeds the macMaxCSMABackoffs, and discarding frame when a NR exceeds macMaxFrameRetries.

Description

Computer execution method and network device

The present invention relates to channel access in wireless communication networks, and more particularly to channel access in IEEE 802.15.4 systems.

With the advent of 5G and other communication technologies, consumer Internet of Things (IoT) devices are becoming increasingly capable of supporting IoT applications. The size of IoT networks has rapidly grown from hundreds to thousands. As more and more devices compete for channel access, the efficiency of the channel access mechanism becomes a key issue that needs to be addressed.

IEEE 802.15.4 is a common wireless standard family developed for indoor and outdoor applications. IEEE 802.15.4 standards have been widely used in commercial products such as Bluetooth and smart meters. IEEE 802.15.4 is designed to operate in the Sub-1 GHz (S1G) band and the 2.4 GHz band. For example, IEEE 802.15.4g can operate in the Sub-1 GHz band and the 2.4 GHz band. An IEEE 802.15.4 network may consist of hundreds to thousands of devices that compete for channel access and cause data loss due to backoff failures. IEEE 802.15.4 uses carrier sense multiple access with collision avoidance (CSMA/CA) mechanism for channel access. For each channel access attempt, IEEE 802.15.4 does not perform channel idleness assessment (CCA) during the backoff period, but only performs CCA after the backoff procedure is completed. This method is suitable for networks with less traffic, but it is not effective for networks with more traffic, especially when coexisting with more interfering networks (such as IEEE 802.11 networks). Therefore, a new channel access mechanism is needed for IEEE 802.15.4 systems.

Therefore, a new channel access method is needed for IEEE 802.15.4 to achieve better performance.

Certain embodiments are based on the following premise: the IEEE 802.15.4 CSMA/CA mechanism is designed for low data rate and low power devices, so energy conservation is very important. Therefore, the IEEE 802.5.4 CSMA/CA mechanism does not support backoff pause and is therefore not well suited for emerging devices that do not have energy consumption constraints (e.g., smart meters).

To this end, some embodiments provide IEEE 802.15.4 with a suspendable CSMA/CA mechanism to support backoff suspension, thereby reducing the probability of packet loss due to backoff failure as shown in FIG. 4 .

Therefore, some embodiments of the present invention provide a suspendable CSMA/CA mechanism for the IEEE 802.15.4 standard, perform CCA in each unit backoff period, and suspend the backoff procedure once a busy channel is detected.

Some embodiments are based on the understanding that energy conservation is important for battery-powered devices. However, for devices such as smart meters that are connected to the power line, energy consumption is not limited. These devices can actively perform CCA to increase the probability of channel access and reduce the probability of fallback failure.

Some embodiments are based on the knowledge that the threshold macMaxCSMABackoffs (maximum backoff number) in the IEEE 802.15.4 CSMA/CA mechanism is used to limit the backoff number (NB). Once the NB exceeds the threshold macMaxCSMABackoffs, the packet will be discarded. As more and more devices compete for channel access, the NB can quickly reach the threshold macMaxCSMABackoffs. Therefore, the IEEE 802.15.4 packet may be discarded.

To this end, suspendable CSMA/CA allows backoff to be suspended, thereby delaying the increase of NB by suspending backoff to avoid packets being discarded when NB exceeds the threshold macMaxCSMABackoffs. By suspending CSMA/CA, CCA after backoff is performed only when the channel is idle in the last backoff cycle, rather than blindly performing CCA after backoff. Blindly performing CCA as shown in Figure 4 increases the probability of backoff failure.

Various embodiments of the present invention are described below with accompanying drawings. It should be noted that the drawings are not drawn to scale, and elements of similar structure or function are represented by similar reference numerals in the drawings. It should also be noted that the drawings are intended only to facilitate the description of specific embodiments of the present invention. They are not intended to be a detailed description of the present invention or to limit the scope of the present invention. In addition, the description in conjunction with a specific embodiment of the present invention is not necessarily limited to that embodiment and may be practiced in any other embodiment of the present invention.

The IEEE 802.15.4 family of standards is a widely used wireless technology for various indoor and outdoor applications. For example, IEEE 802.15.4g is a standard protocol in the IEEE 802.15.4 family of standards designed specifically for outdoor wireless smart utility networks (Wi-SUN). In IEEE 802.15.4g, smart meters have no energy consumption restrictions.

FIG. 1 shows a schematic diagram of an IEEE 802.15.4 network 100. The IEEE 802.15.4 network 100 includes a Personal Area Network Coordinator (PANC) 101 and associated nodes. The PANC and the nodes communicate using an IEEE 802.15.4 wireless link 103.

The topology of the IEEE 802.15.4 network can be star, mesh or tree. For example, the IEEE 802.15.4 network 100 shown in FIG. 1 is a tree topology. In some cases, the IEEE 802.15.4 network 100 can be a smart meter network based on IEEE 802.15.4 configured as a tree topology. It should be noted that the connection method of the tree topology can be changed according to the state of communication. In addition, it is not necessary for all nodes to be directly connected to the PANC 101. In other words, the IEEE 802.15.4 node can communicate with the PANC 101 through a multi-hop method. For example, the IEEE 802.15.4 node 104 can communicate with the PANC 101 through the intermediate IEEE 802.15.4 node 102.

Step 200 of FIG. 2A shows the IEEE 802.15.4 data frame transmission process. In step 201, the IEEE 802.15.4 Media Access Control (MAC) sets the number of retransmissions (NR) to 0. Then, in step 202, the CSMA/CA algorithm is enabled, wherein the standard IEEE 802.15.4-2020 CSMA/CA algorithm is shown in FIG. 3.

In step 203, if the CSMA/CA algorithm returns a success status, it means that the channel is detected to be idle. Therefore, the frame transmission starts in step 204. In step 205, if the frame does not require an acknowledgment message (ACK) (AckTX=0), the IEEE 802.15.4 MAC determines that the transmission is successful in step 207, and reflects the successful transmission status to the upper layer through the data confirmation interface (Data Confirm interface). In step 205, if ACK is required (AckTX=1) and the ACK is received within the ACK waiting time, the IEEE 802.15.4 MAC also determines that the transmission is successful in step 207, and reflects the successful transmission status to the upper layer through the data confirmation interface (Data Confirm interface). In step 206, if ACK is required (AckTX=1) and the ACK is not received within the ACK wait time, the IEEE 802.15.4 MAC increases the NR by one in step 209 and confirms whether the NR exceeds a threshold value macMaxFrameRetries in step 210. If so, the IEEE 802.15.4 MAC determines that the transmission has failed in step 211 and discards the frame. The IEEE 802.15.4 MAC then reflects the status NO_ACK to the upper layer through the data acknowledgment interface. In step 210, if the NR is less than or equal to the threshold value macMaxFrameRetries, the IEEE 802.15.4 MAC makes another transmission attempt.

In step 203, if the CSMA/CA algorithm returns a failure status, the IEEE 802.15.4 MAC checks in step 208 whether the frame is a unicast frame. If the frame is not a unicast frame, the IEEE 802.15.4 MAC determines in step 211 that the transmission has failed and discards the frame, and then reflects the status CHANNEK_ACCESS_FAILURE to the upper layer. If the frame is a unicast frame, the IEEE 802.15.4 MAC increases the NR by one in step 209, and then confirms in step 210 whether the NR exceeds a threshold value macMaxFrameRetries. If so, the IEEE 802.15.4 MAC determines in step 211 that the transmission has failed and discards the frame. The IEEE 802.15.4 MAC then reports the status CHANNEK_ACCESS_FAILURE to the upper layer via the data acknowledgment interface. If the NR is less than or equal to the threshold macMaxFrameRetries, the IEEE 802.15.4 MAC makes another transmission attempt.

FIG. 2B shows an example structure of an IEEE 802.15.4 device 230 forming the network of FIG. 1. The IEEE 802.15.4 device 230 may include a memory 236, a processor 237, a power supply 240, a transceiver 238, and an RF antenna 239. The transceiver 238 includes a transmitter, a receiver, and an energy detector. Further, the storage device includes a control program 231 and is connected to the memory 236, the processor 237, and the transceiver 238. The control program 231 includes a CSMA/CA mode control program 233, a standard CSMA/CA program 234, a suspendable CSMA/CA program 235, and a timer 232. The transceiver 238 uses the timer 232 to execute the CSMA/CA mode control program 233. Depending on the permission of backoff suspension and the intention of the IEEE 802.15.4 device 230 for backoff suspension, the CSMA/CA mode control program 233 may start the standard IEEE 802.15.4 CSMA/CA program 234 or may suspend the CSMA/CA program 235.

FIG. 3 shows the standard CSMA/CA algorithm in IEEE 802.15.4-2020. Embodiments of the present invention provide pausible CSMA/CA for non-slotted IEEE 802.15.4 networks. Therefore, only the non-slotted branch in FIG. 3 is described below. For non-slotted IEEE 802.15.4 networks, i.e., networks without beacons enabled, the standard IEEE 802.15.4 CSMA/CA algorithm initializes the number of backoffs (NB) to 0 and the backoff exponent (BE) to the value macMinBE. The CSMA/CA algorithm then uniformly draws a random number in the interval [0, 2 ^BE -1] called the backoff window or delay window, and delays the random number of unit backoff periods, where the BE starts at the value macMinBE and increases to the value macMaxBE. When the random backoff/delay is completed, the CSMA/CA algorithm performs a clear channel assessment (CCA) operation. If the channel is detected to be idle, the CSMA/CA algorithm returns success and starts transmitting frames. If the channel is detected to be busy, the CSMA/CA algorithm updates NB and BE to NB=NB+1 and BE=min{BE+1,macMaxBE} respectively. If NB exceeds the threshold macMaxCSMABackoffs, the CSMA/CA algorithm will end in failure. Otherwise, the CSMA/CA algorithm continues with random backoffs/delays.

For non-slotted networks, the standard IEEE 802.15.4 CSMA/CA algorithm will first perform a random delay regardless of how long the channel is idle. As shown in Figure 4, because CCA is performed randomly, using this CSMA/CA mechanism based on Backoff+CCA will reduce the channel access probability. IEEE 802.15.4 CSMA/CA Failed Packets Abandoned

In IEEE 802.15.4, data frame transmission failure is caused by a) CSMA/CA failure or b) transmission failure. As shown in Figure 2A, CSMA/CA failure occurs when the NB exceeds the threshold macMaxCSMABackoffs causing the CSMA/CA algorithm to terminate in a failure state. Transmission failures are caused by failed frame transmissions or failed ACK message transmissions or delayed ACK message receptions. When CSMA/CA fails or transmission fails, the number of retransmissions (NR) is incremented by 1. When NR exceeds the threshold macMaxFrameRetries due to CSMA/CA failure, the IEEE 802.15.4 frame is discarded with status CHANNEL_ACCESS_FAILURE. When NR exceeds the threshold macMaxFrameRetries due to transmission failure, the IEEE 802.15.4 frame is discarded with status NO_ACK. As shown in Figure 4, other transmissions may cause CSMA/CA backoff failures, which in turn causes the IEEE 802.15.4 device to discard the packet.

FIG. 4 shows an example of a standard IEEE 802.15.4 CSMA/CA backoff failure caused by other transmissions. However, the pausable CSMA/CA procedure 235 avoids backoff failure by pausing the backoff procedure. In FIG. 4, both the pausable IEEE 802.15.4 CSMA/CA backoff device 401 and the standard IEEE 802.15.4 backoff device 402 receive a data transmission request at time T2, and therefore start backing off at time T2. The pausable IEEE 802.15.4 CSMA/CA backoff device 401 and the standard IEEE 802.15.4 backoff device 402 select the same number of unit backoff cycles, and therefore need to back off for the same amount of time. However, at an earlier time T1, the other device 403 receives the data transmission request and starts backoff. At time T3, the other device 403 completes the backoff and starts the CCA operation. At time T4, the other device 403 completes the CCA and detects an idle channel, and thus starts data transmission. The IEEE 802.15.4 CSMA/CA backoff device 401 that can be suspended performs active CCA within each unit backoff cycle and detects the transmission of the other device 403, and thus suspends its backoff procedure. On the other hand, the standard IEEE 802.15.4 backoff device 402 does not suspend its backoff and completes the backoff at time T5, and thus performs CCA at time T5. However, at time T5, the other device 403 is still transmitting. Therefore, the standard IEEE 802.15.4 backoff device 402 detects that the channel is busy and reports a backoff failure at time T7. At the same time, the IEEE 802.15.4 CSMA/CA backoff device 401 that can be suspended detects the end of the transmission of other devices at time T6 and continues the remaining backoff. At time T8, the IEEE 802.15.4 CSMA/CA backoff device 401 that can be suspended completes the backoff and starts CCA, which ends at time T9 and reports that the channel is idle. Therefore, the IEEE 802.15.4 CSMA/CA backoff device 401 that can be suspended successfully transmits its data at time T9 without a backoff failure.

Figure 4 clearly shows that the standard IEEE 802.15.4 CSMA/CA mechanism causes more packets to be dropped than the suspendable IEEE 802.15.4 CSMA/ CA mechanism.

Some embodiments of the present invention provide IEEE 802.15.4 with a method for suspending CSMA/CA to solve the problem of CSMA/CA failure packet discarding caused by other transmissions.

In order to allow suspendable CSMA/CA, a suspendable CSMA/CA field is defined. When the suspendable CSMA/CA field = 1, it indicates that backoff suspension is allowed. In this case, the IEEE 802.15.4 device may suspend the backoff in the CSMA/CA algorithm. If the IEEE 802.15.4 device intentionally performs backoff suspension, the suspendable CSMA-CA algorithm of step 504 is called. When the suspendable CSMA/CA field = 0, it indicates that backoff suspension is not allowed. In this case, the IEEE 802.15.4 device cannot perform backoff suspension in the CSMA/CA algorithm.

Fallback suspension permission can be determined by regional regulators or network administrators or application developers or a combination of all three, for example, in the United States IEEE 802.15.4 communications are allocated more frequency bands, so fallback suspension is not required, while in Japan IEEE 802.15.4 communications are allocated less frequency bands, so fallback suspension is required.

Even if the Pausable CSMA/CA field = 1, an IEEE 802.15.4 device may choose not to perform fallback pausing, for example, when there is no traffic congestion or the device has limited energy supply.

FIG. 5A shows a flow chart of the IEEE 802.15.4 CSMA/CA supporting backoff pause of the present invention. The CSMA/CA of the present invention allows IEEE 802.15.4 devices to perform backoff pause to avoid channel access failure packet discard.

The CSMA/CA of the present invention in step 500 checks whether the IEEE 802.15.4 network is a time slotted channel hopping (TSCH) network in step 501, and checks whether the IEEE 802.15.4 network is a time slotted network in step 502. For a non-time slotted network, the CSMA/CA of the present invention checks whether a fallback pause is allowed in step 503, i.e., the pausable CSMA/CA field = 1 or 0. If the pausable CSMA/CA field = 1 and the device intends to perform a fallback pause, the CSMA/CA of the present invention continues to perform the pausable CSMA/CA algorithm in step 504.

FIG. 5B illustrates the suspendable CSMA/CA at step 504. At step 505, the suspendable CSMA/CA algorithm sets NB to 0 and BE to the value macMinBE. Then, at step 506, the suspendable CSMA/CA algorithm uniformly draws a random number of unit backoff periods in [0, 2 ^BE -1] and sets the drawn random number as the number of unit backoff periods. Then, as shown in FIG. 5B, at step 507, the suspendable CSMA/CA algorithm performs active CCA in each unit backoff period. In step 508, if the channel is busy, the CSMA/CA algorithm may be suspended in step 514 to wait until the next unit backoff period and perform active CCA in step 507 again. In this case, the number of unit backoff periods (NUBP) is not reduced. In other words, the backoff is suspended because all backoff parameters including NB are not updated. In step 508, if the channel is idle, the CSMA/CA algorithm may be suspended in step 509 to reduce NUBP by 1. In step 510, if NUBP is not 0, the backoff is not completed. Therefore, the CSMA/CA algorithm may be suspended in step 514 to wait until the next unit backoff period and perform active CCA in step 507 again. Otherwise, at step 510, NUBP is 0, and the backoff is complete. Then, the CSMA/CA algorithm can be suspended to execute the standard CCA at step 511. At step 512, if the channel is idle, the backoff is successful at step 513. Otherwise, at step 512, if the channel is busy, the CSMA/CA algorithm can be suspended to increase NB by one at step 515. At step 516, if NB exceeds the predetermined threshold macMaxCSMABackoffs, the backoff fails at step 517. Otherwise, the CSMA/CA algorithm can be suspended to execute another round of backoff.

The main differences between the standard CSMA/CA algorithm and the suspendable CSMA/CA algorithm are:

The CSMA/CA algorithm can be suspended to perform CCA in each unit backoff cycle. The standard CSMA/CA algorithm does not perform CCA during the entire backoff process.

The suspendable CSMA/CA algorithm performs CCA in step 511 only when the channel is detected to be idle during the last unit backoff period. On the other hand, the standard CSMA/CA algorithm performs CCA in step 511 regardless of whether the channel is busy or idle during the last unit backoff period.

The suspendable CSMA/CA algorithm increases the NB only when other transmissions are started during the CCA cycle of the CCA in step 511. On the other hand, the standard CSMA/CA algorithm increases the NB regardless of whether other transmissions are started before the CCA cycle or during the CCA cycle of the CCA in step 511. Therefore, the standard CSMA/CA algorithm has a greater chance of increasing the NB, resulting in a greater possibility of fallback failure.

By performing active CCA, the CSMA/CA algorithm can be suspended to avoid packet discards caused by interference from non-IEEE 802.15.4 devices (such as IEEE 802.11 devices).

In summary, pausing the CSMA/CA algorithm can reduce the probability of backoff failure.

In the IEEE 802.15.4 standard, the unit backoff period is longer than the CCA period. Figure 6 shows the structure of the unit backoff period, which includes the time aTurnaroundTime plus a CCA period. For all PHYs except the SUN physical layer (Physical Payer; PHY) operating in the 920 MHz band, the CCA period is equal to the time aCcaTime. For SUN PHY operating in the 920 MHz band, the CCA period is equal to the time phyCcaDuration. This shows that the CSMA/CA algorithm has multiple options for performing active CCA in step 507 within the unit backoff period. The CSMA/CA algorithm can perform CCA in the entire or partial unit backoff period. FIG. 7A shows an example where the CSMA/CA algorithm performs active CCA in a full unit backoff period. FIG. 7B shows an example where the CSMA/CA algorithm performs active CCA in a CCA period (i.e., a partial unit backoff period).

FIG. 8 illustrates an example of an implementation of a suspendable CSMA/CA algorithm, wherein there are an IEEE 802.15.4 device 801 and other devices 802, wherein the other devices 802 may be IEEE 802.15.4 devices or non-IEEE 802.15.4 devices (e.g., IEEE 802.11 devices). At time T1, the other device 802 receives a data request and thus starts a first backoff. At time T2, the IEEE 802.15.4 device 801 receives a data request and thus also starts a first backoff. At time T3, the other device 802 completes the first backoff and starts a CCA operation. At time T4, the other device 802 completes the CCA and detects that the channel is idle. Therefore, the other device 802 starts transmitting. At the same time of time T4, the IEEE 802.15.4 device 801 detects the transmission of the other device 802. If the other device 802 is an IEEE 802.15.4 device, the IEEE 802.15.4 device 801 suspends its first backoff and performs data reception. At time T5, the other device 802 completes the transmission and the channel becomes idle. Therefore, the IEEE 802.15.4 device 801 continues its first backoff. At time T6, the IEEE 802.15.4 device 801 completes its first backoff and starts the CCA operation. At time T7, the IEEE 802.15.4 device 801 completes the CCA and the channel becomes idle. Therefore, the IEEE 802.15.4 device 801 starts data transmission. At the same time, if the other device 802 is an IEEE 802.15.4 device, it starts receiving data. Finally, at time T8, the IEEE 802.15.4 device 801 completes data transmission.

It should be noted that if the other device 802 is a non-IEEE 802.15.4 device, the IEEE 802.15.4 device 801 and the other device 802 cannot receive data from each other. However, they may interfere with each other. By executing the pausible CSMA/CA algorithm, the IEEE 802.15.4 device 801 can avoid packet discarding due to interference.

In an IEEE 802.15.4 network, a PANC (i.e., a network manager) and multiple devices can implement the suspendable CSMA-CA algorithm of step 504 through the Frame Control field of the Association Response Command of the present invention as shown in FIG. 9A and the Capability Information field of the Association Request Command as shown in FIG. 9B and FIG. 9C. FIG. 9B describes the Capability Information field of the Association Request Command, and FIG. 9C describes the Capability Information field of the Deterministic and Synchronous Multichannel Extension (DSME) Association Request Command. More specifically, the device sets the suspendable CSMA/CA bit (bit 5) in the capability information field of the association request command or DSME association request command to 1 to indicate its intention to perform fallback suspension. In response, the PANC sets the suspendable CSMA/CA bit (bit 7) in the frame control field of the association response command to 1 to indicate that fallback suspension is allowed, or sets the suspendable CSMA/CA bit (bit 7) in the frame control field of the association response command to 0 to indicate that fallback suspension is not allowed. The PANC may determine the permission of fallback suspension based on regional regulators or application requirements or network performance or the number of devices that intend to perform fallback suspension, or a combination of the above.

The above embodiments of the present invention may be implemented in any of a variety of ways. For example, the above embodiments may be implemented in hardware, software, or a combination thereof. When implemented in software, the software code may be executed on any suitable processor or processors, whether in a single computer or distributed across multiple computers. The above processors may be implemented in integrated circuits, wherein one or more processors are located in an integrated circuit element. The processor may be implemented using circuits of any suitable format.

In addition, embodiments of the present invention may be implemented as a method, and examples of the method have been provided. Portions of the method operations may be ordered in any suitable manner. Therefore, even though sequential operations are described in the above embodiments, embodiments may perform operations in a different order than shown, and may include performing some operations simultaneously.

The use of ordinal terms such as "first," "second," and the like in a request item to modify the request item element itself does not imply any priority, precedence, or order of one request item element relative to another request item element, or the temporal order of operations within a method, but is only used to distinguish two request item elements with the same name.

Although the present invention has been described by way of examples of preferred embodiments, it is to be understood that various other variations and modifications may be made within the spirit and scope of the present invention.

Therefore, it is the object of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

100: IEEE 802.15.4 network 101: PANC 102, 104: IEEE 802.15.4 node 103: IEEE 802.15.4 wireless link 200~211: Steps 230: IEEE 802.15.4 device 231: Control program 232: Timer 233: CSMA/CA mode control program 234: Standard CSMA/CA program 235: Pausable CSMA/CA program 236: Memory 237: Memory 238: Transceiver 239: RF antenna 240: Power supply 403: Other devices 402: Standard IEEE 802.15.4 fallback device 401: Can suspend IEEE 802.15.4 CSMA/CA fallback device 500~517: Steps 802: Other devices 801: IEEE 802.15.4 fallback device NO_ACK, CHANNEL_ACCESS_FAILURE: Status T1~T9, aTurnaroundTime, aCcaTime, phyCcaDuration: Time macMinBE, macMaxBE: Value macMaxCSMABackoffs, macMaxFrameRetries: Threshold value

The embodiments of the present disclosure will be further described with the accompanying drawings. The drawings shown are not necessarily drawn to scale, and the focus is on illustrating the principles of the embodiments of the present disclosure. FIG. 1 is a schematic diagram of an IEEE 82.15.4 network of certain embodiments of the present invention; FIG. 2A describes a data transmission flow chart of an embodiment of the present invention and reports the transmission status to the upper layer; FIG. 2B is a structural schematic diagram of an IEEE 802.15.4 CSMA/CA device forming the network of FIG. 1 of an embodiment of the present invention; FIG. 3 shows the standard CSMA/CA algorithm in IEEE 802.15.4-2020 of an embodiment of the present invention FIG. 4 shows the standard IEEE 802.15.4 CSMA/CA algorithm in an embodiment of the present invention, which can be relatively suspended, and may cause more fallback failures. Figure 5A shows a flow chart of the CSMA/CA mechanism used in IEEE 802.15.4 in an embodiment of the present invention. Figure 5B shows a flow chart of the suspendable CSMA/CA method for IEEE 802.15.4 in an embodiment of the present invention; Figure 6 shows the structure of the unit backoff period defined in IEEE 802.15.4 in an embodiment of the present invention; Figure 7A shows an example of performing active CCA in the entire unit backoff period in an embodiment of the present invention; Figure 7B shows an example of performing active CCA in a partial unit backoff period in an embodiment of the present invention; Figure 8 shows an example of performing backoff suspension in a suspendable CSMA/CA mechanism in an embodiment of the present invention; Figure 9A shows the format of the frame control field used to indicate the permission of backoff suspension in the present invention. Figure 9B shows the capability information field of the associated request command invented in the embodiment of the present invention; and Figure 9B shows the capability information field of the DSME associated request command invented in the embodiment of the present invention.

without

100:IEEE 802.15.4 network

101:PANC

102, 104: IEEE 802.15.4 nodes

103:IEEE 802.15.4 wireless link

Claims (20)

A computer-implemented method for executing a carrier sense multiple access with suspendable collision avoidance (CSMA/CA) control program in an IEEE 802.15.4 network, wherein the IEEE 802.15.4 network is composed of a plurality of IEEE 802.15.4 devices, wherein the computer-implemented method causes a processor of one of the IEEE 802.15.4 devices to execute the steps including: Receiving an association response command from a network manager of the IEEE 802.15.4 network to determine permission for a fallback pause; Obtaining the intention of the IEEE 802.15.4 device to execute the fallback pause contained in a suspendable CSMA/CA field in the association request command; If the fallback pause is permitted and the IEEE If the 802.15.4 device intentionally executes the backoff suspension, a suspendable CSMA/CA control program is selected from a memory, wherein the suspendable CSMA/CA control program executes the following steps: Perform active channel idle assessment (CCA) in each unit backoff cycle; When a channel of the IEEE 802.15.4 network is detected as busy, a backoff procedure is suspended; and Once the state of the channel is detected as idle, the backoff procedure is resumed; When the state of the channel is detected as idle, a data frame is transmitted, or when the state of the channel is detected as busy, a backoff number (NB) is increased; and Confirm whether the backoff number exceeds a macMaxCSMABackoffs; When the backoff count exceeds the macMaxCSMABackoffs, a retransmission count (NR) is added, and when the retransmission count exceeds the macMaxFrameRetries, the data frame is discarded. A computer-implemented method as described in claim 1, wherein if the backoff suspension is not permitted, the IEEE 802.15.4 device applies a standard CSMA/CA channel access mechanism, and wherein if the backoff suspension is permitted, the IEEE 802.15.4 device applies a suspendable CSMA/CA channel access mechanism. The computer-implemented method of claim 1, wherein the permission for the backoff suspension is determined by the network manager PANC based on a regional regulator, an application requirement, a network performance, a number of IEEE 802.15.4 devices that intentionally implement the backoff suspension, or a combination thereof. The computer-implemented method of claim 3, wherein the network manager provides the IEEE 802.15.4 devices with the permission for fallback suspension during network establishment, or the IEEE 802.15.4 devices dynamically request the fallback permission from the network manager. The computer-implemented method of claim 4, wherein the IEEE 802.15.4 devices choose not to perform the backoff suspend even if the backoff suspend is permitted. The computer-implemented method of claim 1, wherein the IEEE 802.15.4 device executing the backoff suspension performs the active channel idleness assessment (CCA) during the per-unit backoff cycle and suspends the backoff when a busy channel is detected. A computer-implemented method as described in claim 6, wherein an IEEE 802.15.4 device that executes CSMA/CA that can be suspended first randomly extracts a unit backoff cycle number (NUBP) in [0, 2 ^BE -1], and then performs the active channel idle assessment (CCA) in each unit backoff cycle, wherein if the channel is busy, the backoff procedure is suspended (i.e., the unit backoff cycle number (NUBP) does not decrease), wherein if the channel is idle, the backoff procedure is continued, wherein once the unit backoff cycle number (NUBP) reaches zero, the backoff procedure is completed. The computer-implemented method of claim 6, wherein once the number of unit backoff cycles (NUBP) reaches zero, the IEEE 802.15.4 device performs a standard channel idle assessment (CCA) within a CCA cycle. A computer-implemented method as described in claim 8, wherein if the channel idle assessment (CCA) reports that the channel is idle, the IEEE 802.15.4 device performs data transmission, wherein if the channel idle assessment (CCA) reports that the channel is busy, the CSMA/CA algorithm reports a back-off failure and increases the back-off count by 1. A computer-implemented method as described in claim 9, wherein if the backoff number (NB) exceeds the predetermined macMaxCSMABackoffs, the CSMA/CA algorithm reports a channel access failure, wherein if the CSMA/CA algorithm reports a channel access failure, the retransmission number is increased by 1. The computer-implemented method of claim 10, wherein if the number of retransmissions exceeds macMaxFrameRetries, a medium access control technology (MAC) of IEEE 802.15.4 discards data. The computer-implemented method of claim 6, wherein the IEEE 802.15.4 device can perform the active channel idle assessment (CCA) during the entire unit backoff period or a portion of the unit backoff period. A network device for performing carrier sense multiple access with suspendable collision avoidance (CSMA/CA) in an IEEE 802.15.4 network, comprising: a processor; and a memory configured to store a CSMA/CA mode control program, the CSMA/CA mode control program causing the processor to perform the following steps: receiving an association response command from a network manager of the IEEE 802.15.4 network to determine permission for a fallback pause; obtaining the IEEE 802.15.4 device's intention to perform the fallback pause contained in a suspendable CSMA/CA field in the association request command; if the fallback pause is permitted and the IEEE If the 802.15.4 device intentionally executes the backoff suspension, a suspendable CSMA/CA control program is selected from the memory, wherein the suspendable CSMA/CA control program executes the following steps: Perform active channel idle assessment (CCA) in each unit backoff cycle; When a channel of the IEEE 802.15.4 network is detected as busy, a backoff procedure is suspended; and Once the state of the channel is detected as idle, the backoff procedure is resumed; and When the state of the channel is detected as idle, a data frame is transmitted, or when the state of the channel is detected as busy, a backoff number (NB) is increased; Confirm whether the backoff number (NB) exceeds a macMaxCSMABackoffs; When the backoff count exceeds the macMaxCSMABackoffs, a retransmission count (NR) is added, and when the retransmission count exceeds the macMaxFrameRetries, the data frame is discarded. A network device as described in claim 13, wherein if the fallback suspension is not allowed, the network device applies a standard CSMA/CA channel access mechanism, and wherein if the fallback suspension is allowed, the network device applies a suspendable CSMA/CA channel access mechanism. The network device of claim 13, wherein the permission for the fallback suspension is determined by the network manager, a regional administrator, an application developer, or a combination thereof. The network device as claimed in claim 15, wherein the network manager provides the network device with the permission for the fallback suspension during the network establishment process, or the network device in the IEEE 802.15.4 network dynamically requests the network manager for the permission for the fallback. A network device as claimed in claim 16, wherein even if fallback suspension is permitted, other of the network devices choose not to perform the fallback suspension. A network device as described in claim 13, wherein the network device performs the backoff suspension to perform the active channel idleness assessment (CCA) during the each unit backoff cycle and suspend the backoff process when a channel busy is detected. A network device as described in claim 18, wherein the network device first executes a suspendable CSMA/CA and randomly extracts a unit backoff cycle number (NUBP) in [0, 2 ^BE -1], and then executes the active channel idle assessment (CCA) in each unit backoff cycle, wherein if the channel is busy, the backoff procedure is suspended (i.e., the unit backoff cycle number (NUBP) does not decrease), wherein if the channel is idle, the backoff procedure is continued, wherein once the unit backoff cycle number (NUBP) reaches zero, the backoff procedure is completed. The network device of claim 18, wherein once the number of unit backoff periods (NUBP) reaches zero, the IEEE 802.15.4 device performs a standard channel idle assessment (CCA) within a CCA period.

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