A channel access method based on dual-mode network

Abstract

The application discloses a channel access method based on a dual-mode network, which comprises the following steps: a concentrator CCO node obtains a node MAC address list based on a white list mechanism before network operation, so that the CCO node can make the dual-mode nodes in the MAC address list enter the network during network operation; the identity of each dual-mode node in the network is identified through a short address; the time slot structure of a beacon period on a carrier channel and a wireless channel is allocated with the use right according to a preset allocation and use mechanism according to the short address of the dual-mode network node, so that the transmission of signals is carried out according to the allocation of the use right; wherein the dual-mode network refers to the carrier channel and the wireless channel, the beacon period contains N+1 subframes, N is the number of the dual-mode nodes in the MAC address list, the time slot structure of each subframe is consistent, and the time slot structure of each subframe comprises a dual-function time slot and a CSMA time slot area. The application can reduce channel overhead, has strong robustness, and can maintain the smooth operation of the whole network under a complex channel environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power internet of things, and more particularly, to a channel access method based on a dual-mode network. BACKGROUND

[0002] As an important part of national infrastructure, high-speed carrier communication technology has become the most widely used communication technology in the system because of its excellent communication performance and natural connection with power line communication. With the continuous development of microelectronic technology, the power consumption and volume of communication chips are continuously decreasing, and the mass production of dual-mode chips has engineering feasibility, so that the dual-mode communication technology of high-speed carrier + high-speed wireless has become the main development direction of the next generation of power internet of things communication technology. By August 2021, State Grid Corporation of China has completed the formulation of the dual-mode physical layer standard, but the standard formulation of the link layer has not been determined.

[0003] The channel access mechanism, as one of the core contents of the link layer protocol, determines the signal transmission timing and access process of network nodes in the public channel, and is a key technology that affects the overall communication performance of the network. Therefore, a new physical layer communication mode based on dual-mode communication is needed to study a new efficient comprehensive channel access protocol to maximize the overall communication performance of the dual-mode network. SUMMARY

[0004] The present application provides a channel access method based on a dual-mode network to solve the problem of how to efficiently access the comprehensive channel access protocol and maximize the overall communication performance of the dual-mode network.

[0005] To solve the above problems, according to one aspect of the present application, a channel access method based on a dual-mode network is provided, the method comprising:

[0006] The concentrator CCO node obtains a node MAC address list based on a white list mechanism before the network runs, so that the CCO node can access the dual-mode nodes in the MAC address list during the network operation;

[0007] Each dual-mode node is identified in the network by a short address; wherein the short address of the CCO node is 0 by default, and the short address of the slave node on the MAC address list is assigned by the CCO node when it accesses the network, and the value range is [1, N];

[0008] According to the short address of the dual-mode network node, the time slot structure of the beacon period on the carrier channel and the wireless channel is allocated according to a preset allocation and use mechanism, so as to transmit signals according to the allocation of the use right;

[0009] The dual-mode network refers to a carrier channel and a wireless channel, the beacon period comprises N+1 subframes, N is the number of dual-mode nodes in the MAC address list, the time slot structure of each subframe is consistent, and the time slot structure of each subframe comprises a dual-function time slot and a CSMA time slot area.

[0010] Preferably, according to the short address of the dual-mode network node, the time slot structure of the beacon period on the carrier channel is allocated with the use right according to a preset allocation use mechanism, and the signal is transmitted according to the allocation of the use right, comprising:

[0011] For the time slot structure of the new beacon period on the carrier channel, the network node with the short address n has the priority use right for the carrier dual-function time slot of the subframe n.

[0012] For the carrier subframe 0, the carrier dual-function time slot is fixedly allocated to the CCO node for sending the central beacon signal, and the length of the carrier dual-function time slot is T, and the time slots with a length of 2T before the subsequent CSMA time slot area are only allowed to be used for the CCO to send the central beacon signal.

[0013] For the carrier subframe n, if the node with the short address n is the proxy node PCO on the carrier side, the time slot is fixedly allocated to the node n for sending the proxy beacon signal; if the node is the slave station STA, the time slot is fixedly allocated to the node n, so that the node n can autonomously select to send any type of signal according to the business needs, and is idle when there is no business; if the node has not been networked, the time slot is fixedly allocated to the CCO, so that the CCO can autonomously select to send any type of signal according to the business needs, and is idle when there is no business; 1≤n≤N.

[0014] Preferably, the method further comprises:

[0015] When the CCO node receives signals in the CSMA time slot area, the receiving phase is adjusted according to the number of the subframe, wherein when the number of the subframe is k, the remainder of k divided by 3 is 0, 1 and 2, and the corresponding receiving phases are A phase, B phase and C phase in turn, and when there is a node sending signals to the CCO node in the CSMA time slot area, the receiving phase of the CCO node is selected based on the phase of the node, and the CSMA time slot area of the subframe with the same phase as the phase of the node is selected for signal transmission.

[0016] Preferably, for the time slot structure of the new beacon period on the carrier channel, the specific length of the carrier dual-function time slot is equal to the transmission length of the beacon signal when the length of the signaling content in the frame payload signal reaches the specified upper limit.

[0017] Preferably, the method further comprises: according to the short address of the dual-mode network node, allocating the usage right of the time slot structure of the beacon period on the wireless channel according to a preset allocation usage mechanism, and transmitting the signal according to the allocation of the usage right, comprising:

[0018] The network node with the short address n has the priority usage right of the wireless dual-function time slot of the subframe n for the time slot structure of the beacon period on the wireless channel.

[0019] For the wireless subframe 0, the wireless dual-function time slot is fixedly allocated to the CCO node for transmitting the central beacon signal.

[0020] For the wireless subframe n, if the node with the short address n is the proxy node PCO on the wireless side, the time slot is fixedly allocated to the node n for transmitting the proxy beacon signal; if the node is the slave station STA, the time slot is fixedly allocated to the node n, allowing the node to autonomously select to transmit any type of signal according to the business needs, and to be idle when there is no business; if the node has not yet been networked, the time slot is fixedly allocated to the CCO, allowing the CCO to autonomously select to transmit any type of signal according to the business needs, and to be idle when there is no business; 1≤n≤N.

[0021] Preferably, for the time slot structure of the new beacon period on the wireless channel, the specific length of the wireless dual-function time slot is equal to the transmission length of the beacon signal when the length of the signaling content of the beacon signal reaches a specified upper limit.

[0022] Preferably, the method further comprises: minimizing the signaling content length in the beacon signal by using the following three proxy node message formats, comprising:

[0023] The first proxy node message format: beacon entry header + proxy node message number + proxy node quantity + proxy node full name list; the second proxy node message format: beacon entry header + proxy node message number; and the third proxy node message format: beacon entry header + proxy node message number + newly added proxy node quantity + newly added proxy node name list + newly reduced proxy node quantity + newly reduced proxy node name list.

[0024] The beacon entry header is used to identify the type of the beacon message; the proxy node message number is used to identify the timing of the message content; during the operation of the network, the CCO node uses the first proxy node message format during the period when the network business is relatively idle, and carries all the short addresses of the proxy nodes in the central beacon signal; during the period when the network business load is relatively large, the CCO node uses the second proxy node message format or the third proxy node message format, thereby minimizing the signaling content length in the beacon signal.

[0025] Preferably, the method further comprises:

[0026] If a node receives a beacon signal, and the proxy node message in the beacon signal is in the first proxy node message format and the message number is higher than the message number kept by the node itself, the proxy node information is updated; if the message is in the second proxy node message format and the message number is equal to the message number kept by the node itself, no change is needed; if the message is in the third proxy node message format and the message number is only one higher than the message number kept by the node itself, the proxy node list is updated according to the content; if a message with a message number only two or more higher than the message number kept by the node itself and in the second proxy node message format or the third proxy node message format is received, the node sends a request to its proxy node in the CSMA time slot area, requiring the proxy node to send the latest proxy node list with the latest number to the node, and the proxy node receives the request and then sends the proxy node list in the first proxy node message format in the next beacon period.

[0027] Preferably, the method further comprises:

[0028] The CSMA time slot area of the subframe with the number n is only allowed to be used by the node with the short address n and its one-hop neighbor nodes, and if the node with the number n is not in the network, the substitute is the CCO node; the one-hop neighbor nodes will listen to the synchronization signal header from the start time position of the subframe, if the synchronization is successful, the subsequent signals are received, and after the signal reception is completed, the remaining time slot resources of the subframe will be the CSMA time slot area; and if the synchronization fails, it is considered that the priority node of the whole subframe does not send signals on the dual-function time slot in the beacon period, and then the remaining time slot resources of the subframe will be the CSMA time slot area except the length of the synchronization header signal; wherein the one-hop neighbor nodes refer to the nodes that can correctly receive the signals sent on the dual-function time slot of the subframe.

[0029] The application provides a channel access method based on a dual-mode network, and provides a new time slot structure of a beacon period, including a dual-function time slot and a CSMA time slot area; a concentrator CCO node obtains a node MAC address list based on a white list mechanism before the network is operated, so that the CCO node allows the dual-mode nodes in the MAC address list to enter the network during the operation of the network; the identity of each dual-mode node in the network is identified by a short address; the use right of the time slot structure of the beacon period on the carrier channel and the wireless channel is allocated according to a preset allocation mechanism, according to the allocation of the use right, the signals are transmitted; the channel access method can reduce the channel overhead, meet the ordered channel access demand of the dual-mode nodes with higher efficiency, the protocol content is simple but robust, and the stable operation of the whole network can be maintained in a relatively complex channel environment. BRIEF DESCRIPTION OF DRAWINGS

[0030] The exemplary embodiments of this application can be more fully understood with reference to the following drawings:

[0031] Figure 1 Fig. 1 is a schematic diagram of a tree network topology of a carrier network;

[0032] Figure 2 Fig. 2 is a schematic diagram of a time axis division of a network in a national grid protocol;

[0033] Figure 3 Fig. 3 is a flow chart of a channel access method 300 based on a dual-mode network according to an embodiment of the present application;

[0034] Figure 4 Fig. 4 is a schematic diagram of a time axis division of a dual-mode network according to an embodiment of the present application;

[0035] Figure 5 Fig. 5 is a schematic diagram of a physical layer transmission format of a carrier signal according to an embodiment of the present application;

[0036] Figure 6 Fig. 6 is a schematic diagram of a time slot structure of a carrier side subframe 0 according to an embodiment of the present application;

[0037] Figure 7 Figs. 7(a), 7(b) and 7(c) are schematic diagrams of a first proxy node message format, a second proxy node message format and a third proxy node message format, respectively, according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] Reference will now be made to the exemplary embodiments of the present application with reference to the accompanying drawings, however, the present application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art. The terminology used in the description of the exemplary embodiments presented herein is not intended to be limiting in scope, and is only used to convey the general nature of the present application. In the drawings, like reference numerals are used to indicate like elements throughout the various figures.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0040] In a high-speed carrier communication protocol, tree topology structure and beacon mechanism are two core contents, wherein the tree topology structure refers to a multi-level associated tree network formed with a concentrator (CCO) as the center, a proxy node (PCO) as the relay proxy, and connecting all the slave stations (STAs), such as Figure 1The reason for using tree topology to establish and maintain network routing is that one of the source node and the destination node of all traffic messages in the network must be CCO, the traffic with the destination node as CCO is called upstream traffic message, and the traffic with the source node as CCO is called downstream traffic message. That is, any two nodes in the network other than CCO will not communicate with each other with the other as the destination node of the traffic message.

[0041] The beacon mechanism refers to that CCO as the central control node of network operation uses a superframe time slot structure based on beacon period to carry out network communication, and uses a beacon signal to maintain the synchronization and orderly operation of the entire network. In the high-speed carrier communication protocol formulated by State Grid Corporation, the time slot division of the network in a beacon period is as shown in Figure 2 In the high-speed carrier communication protocol formulated by Southern Power Grid Corporation, a similar frame structure is adopted, but the order of the four time slots is different from that of State Grid, and they are beacon time slot area, CSMA time slot area, TDMA time slot area and bound CSMA time slot area in turn.

[0042] In order to let all network nodes obtain the relevant time slot parameters in the beacon period, the central beacon signal of CCO uses time slot allocation message to carry out Figure 2 the definition of time slot allocation parameters of a beacon period in Table 1 as shown below.

[0043] Table 1 Definition of content of time slot allocation message field

[0044]

[0045]

[0046] Figure 2 The time slot distribution of the beacon period of

[0047] 1. Large traffic delay: a large number of beacon time slots are closely connected, resulting in a long length of the beacon time slot area, and the nodes cannot transmit traffic during this period, so the data traffic generated during this period will have a large waiting delay;

[0048] 2. Large overhead of beacon time slot: due to the complex time slot structure of the beacon period and the large number of parameters, the beacon signal needs to use a large amount of signaling content to describe, resulting in a long length of the beacon signal and occupying a large amount of channel resources;

[0049] Based on the above analysis, this invention provides a novel channel access scheme for the latest dual-mode communication capabilities supported by the physical layer. While inheriting the basic principles of network operation and maintenance of the beacon system and tree topology of the original high-speed carrier link layer protocol, it provides a novel time slot allocation mechanism for the beacon period and corresponding signal transmission and reception rules. This effectively simplifies the signaling content length of the beacon signal and reduces its channel overhead; simultaneously, the uniform and distributed distribution of beacon time slots reduces the waiting latency for service transmission, thus laying the foundation for improving the overall communication performance of the dual-mode network. The specific details are as follows:

[0050] Figure 1 This is a flowchart of a channel access method 100 based on a dual-mode network according to an embodiment of the present invention. Figure 1 As shown, the channel access method based on a dual-mode network provided by this invention offers a novel beacon period time slot structure, including dual-function time slots and CSMA time slot areas. This reduces channel overhead and efficiently meets the ordered channel access requirements of dual-mode nodes. The protocol is simple yet robust, maintaining stable network operation even in complex channel environments. The channel access method 100 based on a dual-mode network provided by this invention begins at step 101. Before network operation, the concentrator CCO node obtains a list of node MAC addresses based on a whitelist mechanism, enabling dual-mode nodes within the MAC address list to join the network during network operation.

[0051] In step 102, each dual-mode node is identified in the network by a short address; the short address of the CCO node is 0 by default, and when the slave nodes on the MAC address list of other nodes enter the network, the CCO node assigns a short address with a value range of [1, N].

[0052] In step 103, based on the short address of the dual-mode network node, the usage rights of the time slot structure of the beacon period on the carrier channel and the wireless channel are allocated according to the preset allocation and usage mechanism, so as to transmit signals according to the allocation of usage rights.

[0053] The dual-mode network refers to the carrier channel and the radio channel. The beacon period contains N+1 subframes, where N is the number of dual-mode nodes in the MAC address list. The time slot structure of each subframe is consistent, and the time slot structure of each subframe includes a dual-function time slot and a CSMA time slot area.

[0054] In this invention, the time axis division of the dual-mode network is specifically as follows: Figure 4As shown, a beacon period contains N+1 subframes, where N represents the number of dual-mode network nodes in the CCO whitelist. The whitelist mechanism means that the CCO manually inputs a list of node MAC addresses before the network starts operating. During network operation, the CCO node will only allow nodes from this list to join the network.

[0055] based on Figure 4 In the time slot structure of the dual-mode network, the upper limit of the dual-mode network node size is consistent with the original high-speed carrier communication standard, which is 1015 nodes. Similar to the original high-speed carrier communication protocol, the dual-mode network uses a 12-bit short address to identify the identity of a dual-mode node in the network. The short address of the CCO node is 0 by default. When other whitelisted slave nodes join the network, the CCO node assigns them a short address with a value in the range of [1, N]. The time slot structure of each subframe is consistent and consists of two types of time slots: a dual-function time slot and a CSMA time slot area.

[0056] Note: The above beacon period time slot structure is based on the premise that the physical layer carrier channel and wireless channel have the ability to work simultaneously, including the ability to transmit and receive signals simultaneously, with one channel transmitting signals and another channel receiving signals.

[0057] Preferably, the method allocates usage rights to the time slot structure of the beacon period on the carrier channel according to a preset allocation mechanism based on the short address of the dual-mode network node, so as to transmit signals according to the allocation of usage rights, including:

[0058] For the time slot structure of the new beacon period on the carrier channel, the network node with the short address n has priority to use the carrier dual-function time slot of subframe n;

[0059] For carrier subframe 0, its carrier dual-function time slot is fixedly allocated to the CCO node for transmitting the central beacon signal. Assuming the length of the carrier dual-function time slot is T, the first 2T of the subsequent CSMA time slot area only allows the CCO to transmit the central beacon signal.

[0060] For carrier subframe n, if the node with short address n is a proxy node PCO on the carrier side, then this time slot is fixedly allocated to node n for it to send proxy beacon signals; if the node is a slave station STA, then this time slot is fixedly allocated to node n, allowing it to choose to send any type of signal according to its own service needs, and it is idle when there is no service; if the node has not yet joined the network, then this time slot is fixedly allocated to CCO, allowing it to choose to send any type of signal according to its own service needs, and it is idle when there is no service; 1≤n≤N.

[0061] Preferably, the method further includes:

[0062] When the CCO node receives signals in the CSMA time slot area, the receiving phase is adjusted according to the number of subframes, wherein the number of subframes is k, the remainder of k divided by 3 is 0, 1 and 2, and the corresponding receiving phase is A phase, B phase and C phase in turn. When there is a node sending signals to the CCO node in the CSMA time slot area, the receiving phase of the CCO node is selected based on the phase of the node, and the CSMA time slot area of the subframe with the same phase as the phase of the node is selected for signal transmission.

[0063] In the application, in the channel access mechanism based on the beacon period, for the beacon period time slot structure on the carrier channel, the carrier dual-function time slot of each subframe adopts a pre-allocation use mechanism, that is, the network with a short address n has a priority use right for the carrier dual-function time slot of the subframe n. The specific rules are as follows:

[0064] (1) The specific length of the carrier dual-function time slot is equal to the transmission length of the beacon signal when the length of the signaling content in the frame payload signal reaches the specified upper limit. The format of one signal transmission of the physical layer is as shown in the following table: Figure 5 The signal format of the synchronization header and the frame control signal of all signals is fixed, and the signal format of the frame payload signal is determined by the specific data length and the corresponding modulation and coding scheme.

[0065] Note: In the existing State Grid high-speed carrier protocol, the coding length of the frame carrier signal of the beacon signal is fixed at 136 bytes or 520 bytes.

[0066] (2) The carrier network uses power lines as its signal transmission channel, and domestic power lines are three-phase four-wire systems, so there are three parallel communication channels of A / B / C phases, and the CCO needs to support signal transmission and reception on the three channels in turn. Therefore, in the application, the carrier dual-function time slot of subframe 0 is fixedly allocated to the CCO node for sending the central beacon signal. Since the central beacon signal needs to be repeatedly sent on the A / B / C three phases,

[0067] Therefore, additional provisions are made for subframe 0 as shown in the following table: Figure 6 The length of the carrier dual-function time slot is T, and the first 2T length of the subsequent CSMA time slot area is only allowed for the CCO to send the central beacon signal.

[0068] (3) On the carrier side, in addition to CCO which needs to take turns to transmit and receive signals in three phases, other nodes only need to be fixed in a phase channel to transmit and receive signals. Therefore, in the present application, it is provided that CCO adjusts the receiving phase when receiving signals in the CSMA time slot area according to the number of subframes. If the number of subframes is k, the remainder of k divided by 3 is 0, 1 and 2, and the corresponding receiving phase is A phase, B phase and C phase in turn. Therefore, if a node needs to send signals to CCO in the CSMA time slot area, it selects the CSMA time slot area of the subframe with the same receiving phase and self phase as CCO based on its own phase to send signals.

[0069] (4) For the carrier subframe n (1≤n≤N), the use rule of the carrier dual-function time slot is: if the node with short address n is a proxy node (PCO) on the carrier side, the time slot is fixedly allocated to the node n for sending a proxy beacon signal; if the node is a slave station (STA), the time slot is fixedly allocated to the node n to enable it to autonomously select any type of signal transmission according to its own business needs, and is idle when there is no business; and if the node has not yet been networked, the time slot is fixedly allocated to CCO to enable it to autonomously select any type of signal transmission according to its own business needs, and is idle when there is no business.

[0070] Preferably, the specific length of the carrier dual-function time slot is equal to the transmission length of the beacon signal when the length of the signaling content in the frame payload signal reaches the prescribed upper limit.

[0071] Preferably, the method allocates the use right of the time slot structure of the beacon period on the wireless channel according to the short address of the dual-mode network node according to a preset allocation and use mechanism to transmit signals according to the allocation of the use right, comprising:

[0072] For the time slot structure of the beacon period on the wireless channel, the network node with short address n has a priority use right for the wireless dual-function time slot of subframe n;

[0073] For the wireless subframe 0, the wireless dual-function time slot is fixedly allocated to the CCO node for sending a central beacon signal;

[0074] For the wireless subframe n, if the node with short address n is a proxy node PCO on the wireless side, the time slot is fixedly allocated to the node n for sending a proxy beacon signal; if the node is a slave station STA, the time slot is fixedly allocated to the node n to enable it to autonomously select any type of signal transmission according to its own business needs, and is idle when there is no business; if the node has not yet been networked, the time slot is fixedly allocated to CCO to enable it to autonomously select any type of signal transmission according to its own business needs, and is idle when there is no business; 1≤n≤N.

[0075] Preferably, the specific length of the wireless dual-function slot is equal to the transmission length of the beacon signal when the length of the signaling content of the beacon signal reaches a prescribed upper limit.

[0076] In the present application, in the channel access mechanism based on beacon period, for the beacon period slot structure on the wireless channel, the wireless dual-function slot of each subframe adopts a pre-allocated use mechanism similar to the carrier wave, i.e., the network with a short address n has the priority to use the wireless dual-function slot of the subframe n. The specific rules are as follows:

[0077] (1) The specific length of the wireless dual-function slot is equal to the transmission length of the beacon signal when the length of the signaling content of the beacon signal reaches a prescribed upper limit.

[0078] (2) The wireless network does not have the channel transmission problem of multiple phases of the carrier network, so for the subframe 0, its wireless dual-function slot is fixedly allocated to the CCO node for transmitting the central beacon signal.

[0079] (3) For the wireless subframe n (1≤n≤N), the use rule of its wireless dual-function slot is as follows: if the node with the short address n is a proxy node (PCO) on the wireless side, the slot is fixedly allocated to the node n for it to transmit the proxy beacon signal; if the node is a slave station (STA), the slot is fixedly allocated to the node n, allowing it to autonomously select to transmit any type of signal according to its own business needs, or to be idle when there is no business; and if the node has not yet been networked, the slot is fixedly allocated to the CCO, allowing it to autonomously select to transmit any type of signal according to its own business needs, or to be idle when there is no business.

[0080] Preferably, the method minimizes the length of the signaling content in the beacon signal by adopting the following three proxy node message formats, including:

[0081] The first proxy node message format: beacon entry header + proxy node message number + proxy node quantity + proxy node full name list; the second proxy node message format: beacon entry header + proxy node message number; and the third proxy node message format: beacon entry header + proxy node message number + newly added proxy node quantity + newly added proxy node name list + newly reduced proxy node quantity + newly reduced proxy node name list.

[0082] The beacon entry head is used to identify the type of the beacon message; the proxy node message number is used to identify the time sequence of the message content; during the operation of the network, when the network traffic is relatively idle, the CCO node uses the first proxy node message format, and the central beacon signal carries the short addresses of all the proxy nodes; when the network traffic is relatively heavy, the CCO node uses the second proxy node message format or the third proxy node message format, so as to minimize the length of the signaling content in the beacon signal.

[0083] Preferably, the method further comprises:

[0084] If a node receives a beacon signal, and the proxy node message in the beacon signal adopts the first proxy node message format and the message number is higher than the message number maintained by the node itself, the proxy node information of the node is updated; if the proxy node message adopts the second proxy node message format and the message number is equal to the message number maintained by the node itself, the node does not need to be changed; if the proxy node message adopts the third proxy node message format and the message number is only one more than the message number maintained by the node itself, the proxy node list is updated according to the content of the message; if the node receives a proxy node message whose message number is more than or equal to two more than the message number maintained by the node itself and the format of the message is the second proxy node message format or the third proxy node message format, the node sends a request to its own proxy node in the CSMA time slot area, requiring the proxy node to send the latest proxy node list with the latest number to the node, and the proxy node receives the request and then sends the proxy node list in the next beacon period using the first proxy node message format.

[0085] Due to the simplification of the time slot structure of the beacon period, the signaling description content in the beacon signal and related to the beacon signal is greatly reduced, and only the following parameters and contents are included:

[0086] 1) The value of N, with a length of 12 bits;

[0087] 2) The number of beacon periods, with a length of 32 bits;

[0088] 3) Network running time (NTB), with a length of 40 bits;

[0089] 4) Proxy node message: since the proxy node list occupies the highest proportion of the beacon signaling content, in order to minimize the length of the signaling content, the proxy node message is adopted as Figure 7The first agent node message format (format 1), the second agent node message format (format 2) and the third agent node message format (format 3) shown in (a), (b) and (c) of the application. Wherein, the beacon entry header is used to identify the type of the beacon message; the agent node message number is used to identify the time sequence of the message content, that is, if the network produces the first group of agent nodes, the message number is 0, then if the agent node list changes, that is, new agent nodes appear or the original agent nodes decrease, the message number will be +1 (note: after 255, it is recycled to 0), and if the agent node list does not change, the message number remains unchanged. In the process of network operation, when the network service is relatively idle, the CCO can use the agent node message format 1, and the central beacon signal carries the short address of all agent nodes; when the network service load is larger, the CCO can use format 2 or format 3, so as to minimize the content length of the beacon signaling. Assuming that there are 100 agent nodes in the network, the length of message 1 is 153 bytes, when the agent nodes do not change, the length of message 2 is only 2 bytes, and if 4 new agent nodes appear and 4 agent nodes decrease, the length of message 3 is only 16 bytes.

[0090] The network of the application is mainly applied to the power grid system, and the device nodes in the network generally do not move in the process of network operation, so the network topology is relatively stable, and after the network agent node set is determined, there is no change or slow change most of the time, so the CCO does not need to send the full list of agent nodes in the central beacon in each beacon period, only needs to notify the network nodes of the small number of changed agent node information, so that the same signaling content is carried and the information transmission correctness is not affected, the signaling content length is greatly saved, and the channel overhead of the network beacon signal is reduced.

[0091] The application also relates to the updating of the proxy node information of a node based on the message number of the proxy node message, so as to further ensure the transmission accuracy of the proxy node information. If a node receives a beacon signal, if the proxy node message in the beacon signal is in format 1 and the message number is higher than the message number kept by the node, the proxy node information of the node is updated; if the message number is equal to the message number kept by the node, it is considered that the proxy node list has not changed, and thus no change is needed; if the message number is only one higher than the message number kept by the node, the proxy node list is updated according to the content; and if the message number is equal to or higher than two than the message number kept by the node, and the format is 2 or 3, it is considered that the node has lost the latest proxy node list, and thus the node can send a request to its proxy node in the CSMA time slot area, and request the proxy node to send the latest proxy node list with the latest number to the node. The proxy node receives the request, and then sends the proxy node list in format 1 in the next beacon period.

[0092] Preferably, the method further comprises:

[0093] The CSMA time slot area of the subframe with the number n is only allowed to be used by the node with the short address n and its one-hop neighbor node, and if the node with the number n is not in the network, the substitute is the CCO node. The one-hop neighbor node listens to the synchronization signal header from the starting time position of the subframe, if the synchronization is successful, the subsequent signal is received, and after the signal receiving is completed, the remaining time slot resources of the subframe are all CSMA time slot areas. If the synchronization fails, it is considered that the priority node of the whole subframe does not send a signal on the dual-purpose time slot in the beacon period, and thus, except for the length of the synchronization header signal, the remaining time slot resources of the subframe are all CSMA time slot areas. The one-hop neighbor node refers to the node which can correctly receive the signal sent on the dual-purpose time slot of the subframe.

[0094] In the application, in order to further reduce the signal transmission collision probability of the carrier and the wireless CSMA time slot area, the following same provisions are added for two channels:

[0095] 1) The CSMA time slot area of the subframe with the number n is only allowed to be used by the node with the short address n and its one-hop neighbor node, and other network nodes are not allowed to use. If the node is not in the network, the substitute is the CCO node. The one-hop neighbor node refers to the node which can correctly receive the signal sent on the dual-purpose time slot of the subframe.

[0096] 2) these neighbor nodes will start to listen the synchronization signal head from the start time position of the subframe, if the synchronization is successful, the following signals are received, and after the signal receiving is completed, the remaining time slot resources of the subframe will be the CSMA time slot area; if the synchronization fails, it is considered that the priority use node of the whole subframe does not send signals on the dual-purpose time slot of the beacon period, and then the remaining time slot resources of the subframe will be the CSMA time slot area except the length of the synchronization head signal.

[0097] The present application provides a new channel access protocol for the dual-mode communication network, the core idea is to refer to the beacon system in the existing high-speed carrier communication standard, but the original superframe time slot structure is redesigned, the channel overhead is reduced, and the ordered channel access demand of the dual-mode node is met with higher efficiency. Theoretical analysis shows that the new channel access protocol inherits some relatively mature design concepts of the existing high-speed carrier communication standard, but the protocol content is simple but robust, and can maintain the smooth operation of the whole network in a relatively complex channel environment.

[0098] The new time slot structure provided by the present application is simple in structure, and an optimized transmission scheme is provided for the information transmission of the proxy node list with the highest content length in the beacon information, which can greatly reduce the signaling content length of the beacon signal and reduce the channel overhead. Meanwhile, a pre-allocation mechanism is adopted for part of the time slot resources, which better guarantees the ordered and conflict-free transmission demand of the signals that need to be periodically transmitted by each network access node, and the range of the competing access nodes of the CSMA time slot area of each subframe is limited according to the local topology structure, the channel competing access points of the whole network nodes are dispersed, the channel collision probability of the process is effectively reduced, and the comprehensive communication performance of the whole network is optimized.

[0099] The present application has been described by referring to a small number of embodiments. However, it is well known to those skilled in the art that other embodiments equivalent to the above disclosure of the present application fall within the scope of the present application, as defined by the attached patent claims.

[0100] Generally, all terms used in the claims are interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise in the specification. All references to "a / an / the [device, component, etc.] are to be construed in open-ended form, unless otherwise specifically stated. Steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0101] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer readable program code.

[0102] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0103] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0104] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0105] Finally, it should be noted that the above-mentioned embodiments are merely intended for describing and illustrating, not limiting the technical solutions of the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A channel access method based on a dual-mode network, characterized in that, The method includes: Before the network is operational, the concentrator CCO node obtains a list of node MAC addresses based on a whitelist mechanism, so that dual-mode nodes in the MAC address list can join the network during the network operation process. Each dual-mode node is identified in the network by a short address; the short address of the CCO node is 0 by default, and when the slave nodes on the MAC address list of other nodes enter the network, the CCO node assigns a short address with a value in the range of [1,N]. Based on the short address of the dual-mode network node, the usage rights of the time slot structure of the beacon period on the carrier channel and the wireless channel are allocated according to the preset allocation and usage mechanism, so as to transmit signals according to the allocation of usage rights. The dual-mode network refers to the carrier channel and the radio channel. The beacon period contains N+1 subframes, where N is the number of dual-mode nodes in the MAC address list. The time slot structure of each subframe is consistent. The time slot structure of each subframe includes a carrier subframe and a radio subframe. Both the carrier subframe and the radio subframe include a dual-function time slot and a CSMA time slot area. The method minimizes the signaling content length in the beacon signal using the following three proxy node message formats: The first proxy node message format is: beacon entry header + proxy node message number + number of proxy nodes + full list of proxy nodes; the second proxy node message format is: beacon entry header + proxy node message number; the third proxy node message format is: beacon entry header + proxy node message number + number of newly added proxy nodes + list of newly added proxy nodes + number of newly removed proxy nodes + list of newly removed proxy nodes. The beacon entry header identifies the type of beacon message; the proxy node message number identifies the timing of the beacon message content; during network operation, during periods of relatively low network traffic, the CCO node uses the first proxy node message format to carry the short addresses of all proxy nodes in the central beacon signal; during periods of high network traffic load, the CCO node uses the second or third proxy node message format to minimize the length of the signaling content in the beacon signal.

2. The method according to claim 1, characterized in that, The method allocates usage rights to the time slot structure of the beacon period on the carrier channel according to the short address of the dual-mode network node and a preset allocation mechanism, so as to transmit signals according to the allocation of usage rights, including: For the time slot structure of the new beacon period on the carrier channel, the network node with the short address n has priority to use the carrier dual-function time slot of subframe n; For carrier subframe 0, its carrier dual-function time slot is fixedly allocated to the CCO node for transmitting the central beacon signal. Assuming the length of the carrier dual-function time slot is T, the first 2T of the subsequent CSMA time slot area only allows the CCO node to transmit the central beacon signal. For carrier subframe n, if the node with short address n is a proxy node PCO on the carrier side, then the carrier dual-function time slot is fixedly allocated to node n for transmitting proxy beacon signals; if the node with short address n is a slave station STA, then the carrier dual-function time slot is fixedly allocated to node n, allowing it to choose to transmit any type of signal according to its own service needs, and it remains idle when there is no service; if the node with short address n has not yet joined the network, then the carrier dual-function time slot is fixedly allocated to the CCO node, allowing it to choose to transmit any type of signal according to its own service needs, and it remains idle when there is no service; 1≤n≤N.

3. The method according to claim 2, characterized in that, The method further includes: When a CCO node receives a signal in a CSMA time slot, it adjusts the receiving phase according to the subframe number. Let the subframe number be k. When k modulo 3 has a remainder of 0, 1, and 2, the corresponding receiving phases are phase A, phase B, and phase C, respectively. When a node sends a signal to the CCO node in a CSMA time slot, it selects the CCO node's receiving phase and the CSMA time slot of the subframe with the same phase as itself for signal transmission based on its own phase.

4. The method according to claim 2, characterized in that, For the time slot structure of the new beacon period on the carrier channel, the specific length of the carrier dual-function time slot is equal to the transmission length of the beacon signal when the length of the signaling content in the frame payload signal reaches the specified upper limit.

5. The method according to claim 1, characterized in that, The method allocates usage rights to the time slot structure of the beacon period on the wireless channel according to the short address of the dual-mode network node and a preset allocation mechanism, so as to transmit signals according to the allocation of usage rights, including: Regarding the time slot structure of the beacon period on the wireless channel, the network node with the short address n has priority to use the wireless dual-function time slot of subframe n; For radio subframe 0, its radio dual-function time slot is fixedly allocated to the CCO node for transmitting the central beacon signal; For radio subframe n, if the node with short address n is a proxy node PCO on the radio side, then the radio dual-function time slot is fixedly allocated to node n for transmitting proxy beacon signals; if the node with short address n is a slave station STA, then the radio dual-function time slot is fixedly allocated to node n, allowing it to choose to transmit any type of signal according to its own service needs, and it remains idle when there is no service; if the node has not yet joined the network, then the radio dual-function time slot is fixedly allocated to the CCO node, allowing it to choose to transmit any type of signal according to its own service needs, and it remains idle when there is no service; 1≤n≤N.

6. The method according to claim 5, characterized in that, For the time slot structure of the new beacon period on the wireless channel, the specific length of the wireless dual-function time slot is equal to the transmission length of the beacon signal when the length of the beacon signal signaling content reaches the specified upper limit.

7. The method according to claim 1, characterized in that, The method further includes: If a node receives a beacon signal and the proxy node message uses the first proxy node message format and has a message number higher than its own stored message number, then the proxy node information is updated. If it uses the second proxy node message format and the message number is equal to its own stored message number, then no change is needed. If it uses the third proxy node message format and the message number is only one greater than its own stored message number, then the proxy node list is updated according to its content. If a node receives a proxy node message with a message number only two greater than its own stored message number and in the format of the second or third proxy node message, then it sends a request to its own proxy node in the CSMA time slot, requesting that it send a proxy node list with the latest number separately. After receiving the request, its proxy node will use the first proxy node message format to send the proxy node list in the next beacon cycle.

8. The method according to claim 1, characterized in that, The method further includes: The CSMA time slot area of ​​subframe number n is only allowed to be used by the node with short address n and its 1-hop neighbor node. If the node with number n has not joined the network, the CCO node will take its place. The 1-hop neighbor node will start listening to the synchronization header from the start time position of subframe number n. If synchronization is successful, it will receive subsequent signals, and after the signal reception is completed, the remaining time slot resources of this subframe will be CSMA time slot area. If synchronization fails, it is assumed that the priority node of the entire subframe has not sent a signal on the dual-function time slot of this beacon period. In this case, except for the synchronization header length, the remaining time slot resources of this subframe will be CSMA time slot area. Here, the 1-hop neighbor node refers to the node that can correctly receive the signal sent on the dual-function time slot of subframe number n.

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