Patent Description:
Although the PLCA defined in IEEE802.3cg may allow the multi-drop network to work efficiently, there is a problem that cannot be ignored in practical applications, that is, the user needs to set the node identity and the number of nodes before the PLCA mechanism is activated, otherwise the PLCA cannot work properly.

In order to solve the problem, some methods have been proposed. However, most of the methods have problems such as easily making the system unstable, and data packets cannot be sent or even discarded due to the back-off time being too long. <CIT> relates to an apparatus to assign device identifier with collision avoidance in a distributed network environment.

Please refer to <FIG>, which is a schematic diagram of a physical layer collision avoidance (PLCA) network according to an embodiment of the disclosure. In <FIG>, a PLCA network <NUM> includes PLCA devices <NUM> to 1N, wherein the PLCA devices <NUM> to 1N may have the same or similar structures. Taking a PLCA device <NUM> as an example, the PLCA device <NUM> includes a communication circuit <NUM>, a random number generator <NUM>, a comparator <NUM>, and a controller <NUM>.

In an embodiment, the communication circuit <NUM> may be used, for example, to implement communication between the PLCA device <NUM> and other PLCA devices in the PLCA network <NUM>, and the communication circuit <NUM> may be implemented as a communication module with a corresponding communication function due to a communication protocol used for packet exchange between the PLCA devices <NUM> to 1N.

In an embodiment, the PLCA devices <NUM> to 1N may, for example, use a carrier sense multiple access with collision detection (CSMA/CD) protocol for packet exchange. In this case, the communication circuit <NUM> may be implemented as a communication module with a CSMA/CD function, but not limited thereto.

In an embodiment, the random number generator <NUM> may be used, for example, to generate a random number as identification information ID0 of the PLCA device <NUM>. In addition, the comparator <NUM> may be used, for example, to compare the identification information ID0 of the PLCA device <NUM> with identification information of other PLCA devices, but not limited thereto.

The controller <NUM> is coupled to the communication circuit <NUM>, the random number generator <NUM>, and the comparator <NUM>, and may be a general purpose processor, a specific purpose processor, a traditional processor, a digital signal processor, multiple microprocessors, one or more microprocessors combined with digital signal processor cores, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other types of integrated circuits, state machines, processors based on advanced RISC machines (ARM), and the like.

In an embodiment, the random number generator <NUM> and the comparator <NUM> may be controlled by the controller <NUM> to implement the above functions. In another embodiment, the random number generator <NUM> and the comparator <NUM> may also be implemented as modules built in the controller <NUM> to implement the above functions, but not limited thereto.

In <FIG>, for the structures of the PLCA devices <NUM> to 1N, reference may be made to the relevant description of the PLCA device <NUM>, which will not be repeated here.

In the embodiment of the disclosure, the controller <NUM> may access specific modules and program codes to implement a method for automatically determining a node identity for a PLCA device proposed by the disclosure, and the details of which are detailed below.

Please refer to <FIG>, which is a flowchart of the method for automatically determining the node identity for the PLCA device according to an embodiment of the disclosure. The method of the embodiment may be executed by the PLCA device <NUM> of <FIG>, and the details of each step of <FIG> will be described below in conjunction with the elements shown in <FIG>.

Generally speaking, before the PLCA network <NUM> actually runs a PLCA mechanism, the embodiment of the disclosure may first automatically decide the node identity for the PLCA device <NUM> through the method shown in <FIG>, and the other PLCA devices <NUM> to 1N may also decide their own node identities based on the same mechanism. After deciding the individual node identities of the PLCA devices <NUM> to 1N, the PLCA network <NUM> may then actually run the PLCA mechanism among the PLCA devices <NUM> to 1N accordingly.

First, in Step S210, the communication circuit <NUM> receives a first synchronization packet, wherein the first synchronization packet includes first identification information of a first PLCA device in the PLCA network <NUM>. In different embodiments, the considered first PLCA device may be any one of the PLCA devices <NUM> to 1N.

For example, assuming that a first synchronization packet PA1 comes from the PLCA device <NUM>, the PLCA device <NUM> may be understood as the considered first PLCA device. In this case, the first synchronization packet is, for example, the first synchronization packet PA1 from the PLCA device <NUM>, and the first identification information therein is, for example, identification information ID1 of the PLCA device <NUM>. For ease of description, it is assumed in <FIG> that the considered first PLCA device is the PLCA device <NUM>, but it is only used as an example and not intended to limit possible implementations of the disclosure.

In an embodiment, the controller <NUM> maintains an identification information table and a device count, wherein the identification information table may, for example, record identification information in all synchronization packets received, and the device count is, for example, the total number of PLCA devices in the PLCA network <NUM> determined by the controller <NUM> based on all the synchronization packets received.

Based on this, in Step S220, the controller <NUM> generates the random number as the identification information ID0 of the PLCA device <NUM>, and determines a first comparison result between the identification information ID0 of the PLCA device <NUM> and the first identification information (for example, the identification information ID1) of the first PLCA device in Step S230.

In an embodiment, the controller <NUM> may request the random number generator <NUM> to generate the random number as the identification information ID0, and request the comparator <NUM> to determine the first comparison result between the identification information ID0 and the first identification information (for example, the identification information ID1). In an embodiment, the first identification information (for example, the identification information ID1) is another random number generated by the random number generator in the first PLCA device (for example, the PLCA device <NUM>).

In an embodiment, the first comparison result may, for example, specify that the identification information ID0 is the same as or different from the first identification information, but not limited thereto.

In Step S240, the controller <NUM> updates the identification information table and the device count based on the first comparison result. In Step S250, the controller <NUM> controls the communication circuit <NUM> to send a synchronization packet PA0 corresponding to the PLCA device <NUM> based on the first comparison result.

In an embodiment, in response to the first comparison result indicating that the identification information ID0 of the PLCA device <NUM> is different from the first identification information (for example, the identification information ID1) of the first PLCA device, it means that the PLCA device <NUM> and the first PLCA device do not use duplicate identification information. In this case, the controller <NUM> may determine whether the first identification information of the first PLCA device is recorded in the identification information table of the PLCA device <NUM>.

In a first embodiment, in response to determining that the first identification information (for example, the identification information ID1) of the first PLCA device is not recorded in the identification information table of the PLCA device <NUM>, it means that the first PLCA device is an unfamiliar PLCA device to the PLCA device <NUM> currently. In this case, the controller <NUM> updates the identification information table by adding the first identification information (for example, the identification information ID1) of the first PLCA device into the identification information table, and updates the device count by incrementing the device count.

Afterwards, the controller <NUM> controls the communication circuit <NUM> to send the synchronization packet PA0 corresponding to the PLCA device, wherein the synchronization packet PA0 includes the identification information ID0 of the PLCA device. In other words, when the PLCA device <NUM> receives a synchronization packet from the unfamiliar first PLCA device, the PLCA device <NUM> not only updates the identification information table and the device count accordingly, but also sends (for example, broadcasts) the synchronization packet PA0 including its own identification information ID0. In this case, if the first PLCA device receives the synchronization packet PA0, the first PLCA device may also determine whether to update the identification information table and the device count maintained by the first PLCA device according to the synchronization packet PA0 based on the mechanism taught above. Similarly, when other PLCA devices receive the first synchronization packet PA1 and/or the synchronization packet PA0, the other PLCA devices may also determine whether to update the identification information tables and the device counts maintained by themselves according to the first synchronization packet PA1 and/or the synchronization packet PA0.

In a second embodiment, in response to determining that the first identification information (for example, the identification information ID1) of the first PLCA device is recorded in the identification information table of the PLCA device <NUM>, it means that the PLCA device <NUM> has previously received other synchronization packets from the first PLCA device, and has recorded the corresponding first identification information ID1 in the identification information table. In other words, the first PLCA device is not an unfamiliar PLCA device to the PLCA device <NUM> currently. In this case, the controller <NUM> may reset a packet detection time of the PLCA device without updating the identification information table and the device count.

In an embodiment, the packet detection time is, for example, a cumulative time when the PLCA device <NUM> has not received any synchronization packet from other PLCA devices. In the embodiment of the disclosure, if the cumulative packet detection time of the PLCA device <NUM> is not less than a preset time threshold (which may be determined by a designer according to requirements), it means that the information owned by each of the PLCA devices <NUM> to 1N (for example, the identification information tables and the device counts individually maintained by the PLCA devices <NUM> to 1N) are sufficient to be used to decide the node identity of each of the PLCA devices <NUM> to 1N, but not limited thereto.

In a third embodiment, in response to determining that the first comparison result indicates that the identification information ID0 of the PLCA device <NUM> is the same as the first identification information (for example, the identification information ID1) of the first PLCA device, it means that the PLCA device <NUM> and the first PLCA device use duplicate identification information (which may be referred to as an identification information conflict). In this case, the controller <NUM> updates the identification information table by resetting (for example, clearing) the identification information table, and updates the device count by resetting (for example, clearing) the device count.

Moreover, the controller <NUM> may (control the random number generator <NUM> to) generate another random number as the new identification information ID0 of the PLCA device, and control the communication circuit <NUM> to send a resynchronization packet RS and the synchronization packet PA0 corresponding to the PLCA device <NUM>, wherein the synchronization packet PA0 includes the new identification information ID0 of the PLCA device <NUM>. Since the new identification information ID0 at this time corresponds to another random number, the new identification information ID0 should be different from the (old) identification information ID0 included in the synchronization packet PA0 in the first embodiment.

In the third embodiment, the resynchronization packet RS is at least used to trigger the first PLCA device to reset the corresponding identification information table, reset the corresponding device count, regenerate the corresponding first identification information ID1, and send the first synchronization packet PA1 including the new first identification information ID1. Similarly, when other PLCA devices receive resynchronization packets, the other PLCA devices also reset the corresponding identification information tables, reset the corresponding device counts, regenerate the corresponding identification information, and send the synchronization packets including the newly generated identification information.

In other words, when the PLCA device <NUM> finds that the identification information conflict occurs, the PLCA device <NUM> may request the other PLCA devices <NUM> to 1N to reset the corresponding identification information tables, reset the corresponding device counts, regenerate the corresponding identification information, and send the synchronization packets including the newly generated identification information through the resynchronization packet RS.

For example, when the PLCA device <NUM> receives the resynchronization packet RS, the PLCA device <NUM> resets the identification information table, resets the device count, regenerates corresponding identification information ID2 (for example, a random number), and sends (for example, broadcasts) a synchronization packet PA2 including the newly generated identification information ID2. For another example, when the PLCA device 1N receives the resynchronization packet RS, the PLCA device 1N resets the identification information table, resets the device count, regenerates corresponding identification information IDN (for example, a random number), and sends (for example, broadcasts) a synchronization packet PAN including the newly generated identification information IDN.

In this case, the PLCA device <NUM> receives the corresponding synchronization packets PA1 to PAN from each of the PLCA devices <NUM> to 1N, and the synchronization packets PA1 to PAN individually includes the newly generated identification information of the corresponding PLCA device.

In the third embodiment, since the PLCA device <NUM> has reset (for example, cleared) the identification information table and reset (for example, cleared) the device count, the PLCA devices <NUM> to 1N are all unfamiliar to the PLCA device <NUM>. Therefore, each time one of the synchronization packets PA1 to PAN is received, the PLCA device <NUM> records the identification information therein in the identification information table maintained by the PLCA device <NUM>, and increments the device count.

In an embodiment, if the identification information ID0 to IDN are different from each other (that is, there is no identification information conflict), the PLCA device <NUM> will record the corresponding identification information ID1 to IDN in the identification information table maintained by the PLCA device <NUM> due to the synchronization packets PA1 to PAN, and gradually increment the device count.

As mentioned in the first embodiment, when the PLCA device <NUM> receives a synchronization packet from an unfamiliar PLCA device, in addition to updating the identification information table and the device count accordingly, the PLCA device <NUM> also sends the synchronization packet PA0. In other words, the PLCA device <NUM> may repeatedly send the synchronization packet PA0.

Based on similar principles, other PLCA devices may also repeatedly send corresponding synchronization packets, so that the PLCA device <NUM> repeatedly receives the same synchronization packets. In this case, the PLCA device <NUM> may update the packet detection time based on the teachings in the second embodiment, but not limited thereto.

In the scenario of <FIG>, assuming that there is no identification information conflict, the identification information table maintained by the PLCA device <NUM> eventually records at least the identification information ID1 to IDN of the PLCA devices <NUM> to 1N, and the recorded device count is not less than the total number of the PLCA devices <NUM> to 1N.

In an embodiment, after resetting the identification information table and the device count, the controller <NUM> may also add the new identification information ID0 into the identification information table at any point in time, and increment the device count due to the PLCA device <NUM> itself. In this case, the identification information table maintained by the PLCA device <NUM> eventually records the identification information ID0 to IDN of the PLCA devices <NUM> to 1N, and the recorded device count is equal to the total number of the PLCA devices <NUM> to 1N, but not limited thereto.

Similarly, when there is no identification information conflict, the identification information tables individually maintained by the other PLCA devices <NUM> to 1N also eventually record the identification information ID0 to IDN of the PLCA devices <NUM> to 1N, and the recorded device counts are also equal to the total number of the PLCA devices <NUM> to 1N.

However, if any one of the PLCA devices <NUM> to 1N determines that there is an identification information conflict again, the mechanism of the third embodiment will be executed again until there is no identification information conflict, but not limited thereto.

In an embodiment, in response to determining that the synchronization packet PA0 experiences a packet collision (for example, the synchronization packet PA0 collides with other synchronization packets), the controller <NUM> may increment a cumulative number of collisions of the synchronization packet PA0, and re-send the synchronization packet PA0 after waiting for a back-off time, wherein the back-off time is associated with the cumulative number of collisions.

In an embodiment, the back-off time is characterized by D*k, where D is a specific bit time and k is <NUM>n - <NUM>, where n is the cumulative number of collisions.

In an embodiment, the specific bit time may vary due to the communication environment considered. For example, in the 10BASE-T1S communication specification, the corresponding specific bit time may be selected as 192BT (bit time), which corresponds to <NUM>. Furthermore, in different embodiments, when n is greater than a corresponding upper limit value (expressed as p), k may be set to a fixed value (for example, <NUM>^p-<NUM>).

In an embodiment, assuming that the upper limit value corresponding to n is <NUM>, and the specific bit time considered is 192BT, the corresponding back-off time may be illustrated in Table <NUM> below.

Next, in Step S260, the controller <NUM> determines the node identity for the PLCA device <NUM> in the PLCA network <NUM> based on the identification information table.

In an embodiment, the controller <NUM> may execute Step S260 after determining that the cumulative packet detection time is no longer less than the preset time threshold. Specifically, when the controller <NUM> determines that the cumulative packet detection time is no longer less than the preset time threshold, it means that no PLCA device sends its own synchronization packet due to a synchronization packet from an unfamiliar PLCA device. In other words, none of the PLCA devices <NUM> to 1N are unfamiliar with each other. In this case, the controller <NUM> may determine the node identity for the PLCA device <NUM> based on the maintained identification information table, but not limited thereto.

In an embodiment, the controller <NUM> sorts the identification information ID0 to IDN of the PLCA devices <NUM> to 1N in the maintained identification information table in a descending sequence or an ascending sequence, and decides the node identity of the PLCA device <NUM> in the PLCA network <NUM> according to the sequence of the identification information ID0 of the PLCA device <NUM> in the identification information table.

In an embodiment, the node identity of the PLCA device <NUM> is, for example, a node number, wherein the node number corresponds to the sequence of the identification information ID0 of the PLCA device <NUM> in the identification information table. For example, taking the descending sequence sorting as an example, if the sequence of the identification information ID0 of the PLCA device <NUM> in the identification information table is <NUM>, the node number of the PLCA device <NUM> is, for example, <NUM>, and the node number may be used as the node identity of the PLCA device <NUM>. For another example, if the sequence of the identification information ID0 of the PLCA device <NUM> in the identification information table is <NUM>, the node number of the PLCA device <NUM> is, for example, <NUM>, and the node number may be used as the node identity of the PLCA device <NUM>, but not limited thereto.

In addition, the other PLCA devices <NUM> to 1N may also decide their own node numbers and/or node identities based on the same principle.

From the above, it can be seen that the method provided by the embodiment of the disclosure allows the PLCA devices <NUM> to 1N in the PLCA network <NUM> to automatically determine the node identities in the PLCA network <NUM>.

After determining the node identity of the PLCA device <NUM>, the controller <NUM> may also determine the transmission opportunity (TO) of the PLCA device <NUM> in the PLCA network <NUM> accordingly.

In an embodiment, the transmission opportunity of the PLCA device <NUM> in the PLCA network <NUM> may correspond to the node number of the PLCA device <NUM>. For example, if the node number of the PLCA device <NUM> is <NUM>, the controller <NUM> may determine that the sequence of the PLCA device <NUM> for transmission is the 9th among the PLCA devices <NUM> to 1N. For another example, if the node number of the PLCA device <NUM> is <NUM>, the controller <NUM> may determine that the sequence of the PLCA device <NUM> for transmission is the 21st among the PLCA devices <NUM> to 1N, but not limited thereto.

As mentioned earlier, after deciding the individual node identities of the PLCA devices <NUM> to 1N, the PLCA network <NUM> may then actually run the PLCA mechanism among the PLCA devices <NUM> to 1N accordingly.

In the PLCA mechanism, the PLCA devices <NUM> to 1N transmit according to the corresponding transmission opportunities. For example, assuming that the PLCA devices <NUM> to 1N respectively correspond to node numbers <NUM> to N, the PLCA devices <NUM> to 1N transmit in sequence. After the transmission opportunity of the PLCA device 1N ends, it will be the turn of the transmission opportunity of the PLCA device <NUM> again.

In an embodiment, the disclosure further proposes a method for allowing a new PLCA device to join the PLCA network <NUM> after running the PLCA mechanism. Specifically, for the newly added PLCA device (hereinafter referred to as a second PLCA device), the second PLCA device may send (for example, broadcast) a second synchronization packet including the second identification information to the PLCA network <NUM> after generating a random number as its own identification information (hereinafter referred to as second identification information).

In this case, the PLCA device <NUM> may determine a second comparison result between the identification information ID0 of the PLCA device <NUM> and the second identification information of the second PLCA device by the comparator <NUM> after the communication circuit <NUM> receives the second synchronization packet. Afterwards, the controller <NUM> may update the identification information table and the device count based on the second comparison result, and control the communication circuit <NUM> to send the synchronization packet PA0 corresponding to the PLCA device <NUM> based on the second comparison result.

In an embodiment, the second comparison result may, for example, specify that the identification information ID0 is the same as or different from the second identification information, but not limited thereto.

Similarly, other PLCA devices may also execute the above operations due to the second synchronization packet.

In a fourth embodiment, in response to determining that the second comparison result indicates that the identification information ID0 is different from the second identification information, and the second identification information is not recorded in the identification information table, it means that the second PLCA device is an unfamiliar PLCA device to the PLCA device <NUM>. Based on this, the controller <NUM> may update the identification information table by resetting the identification information table, and update the device count by resetting the device count. After that, the controller <NUM> may control the communication circuit <NUM> to send the synchronization packet PA0 corresponding to the PLCA device <NUM>.

In this case, the second PLCA device adds the identification information ID0 into the identification information table maintained by the second PLCA device due to the synchronization packet PA0 and increments the device count. Afterwards, the second PLCA device may re-send the second synchronization packet.

Similarly, the other PLCA devices <NUM> to 1N also individually reset the identification information tables, reset the device counts, and send the corresponding synchronization packets PA1 to PAN due to the second synchronization packet.

Since the identification information table and the device count of the PLCA device <NUM> have been reset, all other PLCA devices are unfamiliar to the PLCA device <NUM>. Based on this, the PLCA device <NUM> continuously updates the identification information table and the device count due to the synchronization packets PA1 to PAN and the second synchronization packet. Similarly, the other PLCA devices <NUM> to 1N and the second PLCA device also continuously update the maintained identification information tables and device counts due to the synchronization packets PA1 to PAN and/or the second synchronization packet.

In this case, the identification information table maintained by the PLCA device <NUM> eventually records the identification information ID0 to IDN and the second identification information, and the recorded device count is equal to the total number of the PLCA devices <NUM> to 1N and the second PLCA device, but not limited thereto. Similarly, the identification information tables individually maintained by the other PLCA devices <NUM> to 1N and the second PLCA device also eventually record the identification information ID0 to IDN and the second identification information, and the recorded device counts are equal to the total number of the PLCA devices <NUM> to 1N and the second PLCA device.

Afterwards, the PLCA device <NUM> (and other PLCA devices in the PLCA network <NUM>) may then decide their own node identities and/or node numbers according to the teachings of the previous embodiments, and run the PLCA mechanism again according to the corresponding transmission opportunities, but not limited thereto.

In a fifth embodiment, in response to determining that the second comparison result indicates that the identification information ID0 is the same as the second identification information, it means that the PLCA device <NUM> and the second PLCA device use duplicate identification information (that is, an identification information conflict occurs). In this case, the controller <NUM> updates the identification information table by resetting (for example, clearing) the identification information table, and updates the device count by resetting (for example, clearing) the device count.

Moreover, the controller <NUM> may (control the random number generator <NUM> to) generate another random number as the new identification information ID0 of the PLCA device, and control the communication circuit <NUM> to send the resynchronization packet RS and the synchronization packet PA0 corresponding to the PLCA device <NUM>, wherein the synchronization packet PA0 includes the new identification information ID0 of the PLCA device <NUM>.

From another point of view, when the PLCA device <NUM> determines that the PLCA device <NUM> and the second PLCA device use duplicate identification information, the PLCA device <NUM> may correspondingly execute the content of the third embodiment. For relevant details, reference may be made to the description of the third embodiment, which will not be repeated here.

In a sixth embodiment, in response to determining that a packet collision is detected when the PLCA device <NUM> executes the corresponding transmission opportunity, it means that an unknown PLCA device is sending a packet. Specifically, when any one of the PLCA devices <NUM> to 1N decides its own transmission opportunity, the transmission opportunities corresponding to other PLCA devices are also known at the same time. Therefore, if a certain PLCA device sends a packet when other PLCA devices execute the corresponding transmission opportunities, it means that the PLCA device is not an original member (that is, is a new PLCA device) in the PLCA network <NUM>.

Therefore, when the PLCA device <NUM> detects a packet collision when executing the corresponding transmission opportunity, the controller <NUM> may correspondingly reset the identification information table, reset the device count, and generate another random number as the new identification information ID0 of the PLCA device <NUM>. Afterwards, the controller <NUM> may control the communication circuit <NUM> to send the resynchronization packet RS and the synchronization packet PA0 corresponding to the PLCA device <NUM>, wherein the synchronization packet PA0 includes the new identification information ID0 of the PLCA device.

From another point of view, when the PLCA device <NUM> determines that a packet collision is detected when executing the transmission opportunity, the PLCA device <NUM> may correspondingly execute the content of the third embodiment. For relevant details, reference may be made to the description of the third embodiment, which will not be repeated here.

In an embodiment, after the PLCA devices <NUM> to 1N decide their own node identities and/or node numbers, the PLCA devices <NUM> to 1N may also determine whether they are main nodes in the PLCA network <NUM> accordingly.

In the embodiment of the disclosure, a PLCA device with a specific node identity and/or a specific node number may be referred to as a main node. For ease of description, it is assumed that the PLCA device with the node number <NUM> is the main node in the PLCA network <NUM>, but not limited thereto.

In a seventh embodiment, assuming that the PLCA device <NUM> is the main node, the controller <NUM> may determine whether there is a specific PLCA device among the other PLCA devices <NUM> to 1N, wherein the specific PLCA device does not execute any transmission operation in the corresponding transmission opportunity.

In response to determining that there is the PLCA device, it means that there is an idle PLCA device or a removed PLCA device not actually transmitting in the PLCA network <NUM>. In this case, the controller <NUM> may reset the identification information table, reset the device count, and generate another random number as the new identification information ID0 of the PLCA device <NUM>. Afterwards, the controller <NUM> may control the communication circuit <NUM> to send the resynchronization packet RS and the synchronization packet PA0 corresponding to the PLCA device <NUM>, wherein the synchronization packet PA0 includes the new identification information ID0 of the PLCA device <NUM>.

From another point of view, when the PLCA device <NUM> determines that there is the idle PLCA device or the removed PLCA device, the PLCA device <NUM> may correspondingly execute the content of the third embodiment. For relevant details, reference may be made to the description of the third embodiment, which will not be repeated here.

Please refer to <FIG>, which is a schematic diagram of a packet format according to an embodiment of the disclosure. In <FIG>, a packet format <NUM> includes, for example, a preamble <NUM>, a start of frame delimiter (SFD) <NUM>, a destination address (DA) <NUM>, a source address (SA) <NUM>, a size <NUM>, a payload <NUM>, and a frame check sequence (FCS) <NUM>.

In different embodiments, the synchronization packet and the resynchronization packet may both have the format shown in <FIG>, but the difference between the synchronization packet and the resynchronization packet mainly lies in the content of the payload <NUM>.

In an embodiment, when the packet format <NUM> is used to implement the synchronization packet, the content of the payload <NUM> is, for example, "0x0000_0000_nodeID_0000", wherein nodeID is, for example, the identification information of the PLCA device sending the synchronization packet. In addition, when the packet format <NUM> is used to implement the resynchronization packet, the content of the payload <NUM> is, for example, "0x0000_0000_nodeID_00FF", wherein nodeID is, for example, the identification information of the PLCA device sending the resynchronization packet.

In addition, the destination address <NUM> records, for example, the address of the PLCA device that should receive the synchronization packet and/or the resynchronization packet. In <FIG>, when the destination address <NUM> is set to the form as shown, it may be understood as broadcasting the packet, but not limited thereto.

In addition, the source address <NUM> records, for example, the address of the PLCA device sending the synchronization packet and/or the resynchronization packet. In <FIG>, the address of the PLCA device sending the synchronization packet and/or the resynchronization packet may be expressed as "0x0000_0000_nodeID", but not limited thereto.

Claim 1:
A physical layer collision avoidance device (<NUM>-1N), comprising:
a communication circuit (<NUM>), used to receive a first synchronization packet (PA0-PAN), wherein the first synchronization packet (PAO-PAN) comprises first identification information (IDO-IDN) of a first physical layer collision avoidance device (<NUM>-1N);
a controller (<NUM>), coupled to the communication circuit (<NUM>) and maintaining an identification information table and a device count, wherein the controller (<NUM>) is configured to:
generate a random number as identification information (IDO-IDN) of the physical layer collision avoidance device (<NUM>-1N);
determine a first comparison result between the identification information (IDO-IDN) of the physical layer collision avoidance device (<NUM>-1N) and the first identification information (IDO-IDN) of the first physical layer collision avoidance device (<NUM>-1N);
update the identification information table and the device count based on the first comparison result;
control the communication circuit (<NUM>) to send a synchronization packet (PAO-PAN) corresponding to the physical layer collision avoidance device (<NUM>-1N) based on the first comparison result; and
determine a node identity for the physical layer collision avoidance device (<NUM>-1N) in a physical layer collision avoidance network (<NUM>) based on the identification information table.