CN112543040A

CN112543040A - Efficient BPLC network networking method

Info

Publication number: CN112543040A
Application number: CN202011361881.1A
Authority: CN
Inventors: 任智; 任冬; 周佳琦; 刘顺辉; 吴本源; 曹建玲
Original assignee: Chongqing University of Post and Telecommunications
Current assignee: Chongqing University of Post and Telecommunications
Priority date: 2020-11-27
Filing date: 2020-11-27
Publication date: 2021-03-23
Anticipated expiration: 2040-11-27
Also published as: CN112543040B

Abstract

The invention requests to protect a high-efficiency BPLC network networking method, which comprises designing a CCO self-adaptive multicast sending association confirmation frame mechanism and an association request frame self-adaptive waiting retransmission mechanism; in the self-adaptive multicast associated acknowledgement frame sending mechanism, when a plurality of associated acknowledgement frames are to be sent, one associated acknowledgement multicast frame is used for sending a group of reply messages; in the association request frame self-adaptive retransmission waiting mechanism, an association reply frame which cannot be sent in a CSMA time slot is sent to a CCO node for a period of time, so that the time when an STA retransmits an association request message falls in any time slot of a beacon period, and unnecessary retransmission of the association request frame can be effectively reduced.

Description

Efficient BPLC network networking method

Technical Field

The invention belongs to the field of power communication, and particularly relates to a low-voltage broadband power line carrier communication technology.

Background

With the trend that a smart power grid gradually replaces a traditional power grid, a power network is used as a network with the widest coverage and the most transmission nodes, which means that any charged terminal can become a starting point and an end point of information transmission, undoubtedly, huge information resources can be provided for people, and the network becomes a main communication medium of a ubiquitous power internet of things in the future. The low voltage broadband power line carrier communication (BPLC) is a communication method that uses a low voltage power distribution line (380/220V subscriber line) as an information transmission medium to transmit voice or data, and compared with the unstable penetration capability of a wireless network, the power line communication network has the natural advantages of no need of rewiring, wide coverage area, low cost and the like. The broadband power line carrier communication bandwidth is wide, and the basic frequency band is 1 MHz-20 MHz. Compared with the traditional narrow-band power line carrier communication, the broadband PLC has the advantages of higher transmission rate, stronger anti-interference performance and better performance. Currently, the international standard for broadband power line carrier communication is IEEE 1901.1. The standard is based on the technical specification of interconnection and intercommunication of low-voltage power line broadband power line carrier communication of the national grid company Q/GDW 11612, and the effective application of the technology of internet of things based on the power line carrier communication in the energy internet is realized. At present, the BPLC network is widely applied to the fields of automatic meter reading, intelligent power utilization systems, street lamp control, charging pile construction and the like. At present, power line communication is used as a novel transmission medium to play a great innovative application under an internet of things platform, and as shown in fig. 1, a power line communication network plays a wide role in the internet of things industry, public application, family and personal application.

Prior art closest to the present invention

The closest prior art to the present invention comes from: red light, Zheng Jian hong, Luo Yi Jing, Tengdangyang, an automatic networking method, a device and a system [ P ] CN106357305A,2017-01-25 of a tree-structure network.

Technical scheme of prior art I

The technical scheme of the prior art I comprises the following specific contents:

the invention discloses a broadband power line carrier communication networking method, and the like, wherein the method comprises the following steps: the beacon information is periodically transmitted after the central control node is powered on. After receiving the discovery beacon, the STA station which does not access the network generates an association request frame according to the indication of the association start flag bit in the beacon, and sends the association request frame to the central control node. The central control node receives the association request information sent by the network access application node, processes the association request information, checks the validity of the association request node, and if the association request node is valid, the CCO sends association confirmation information to the request node to the primary site requesting network access.

According to the research, the main disadvantages of the first prior art are:

1) in the technology, when the network scale is large, the number of association confirmation messages in a CCO queue is large, the time for waiting for sending is long, and the time for waiting for the association confirmation messages by association request frames is long, so that the time delay of adopting unicast reply is large.

2) Each STA sending an association request frame needs the same number of association confirmation frames to reply, which is likely to cause channel congestion and lower network throughput in the case of a large network scale.

3) When the technology sends a plurality of associated acknowledgement frames, each frame needs a certain overhead, so the generated total overhead is the sum of all associated acknowledgement frame overheads, and the head of each frame has the same repeated field, which causes a large amount of control overhead. However, by sending multiple association reply frames at once using multicast, the overhead can be reduced to that required for one frame when the combined frame does not exceed the maximum frame length.

Prior art two closest to the present invention

The second closest prior art to the present invention comes from: part 4-2 of the Q GDW 11612.42-2016 low-voltage power line broadband power line carrier communication interconnection technical specification: data link layer

Technical scheme of prior art II

The second technical solution in the prior art includes the following specific contents:

after the STA sends the association request, it needs to wait for the CCO to process the association request frame, and then the association acknowledgement frame sent by the CCO or the association acknowledgement frame sent by the proxy station. And the STA judges whether the network access is successful according to the result in the frame. If the association confirmation frame is not received, the association request can be reinitiated; if the network access request is rejected, the STA can wait for a time interval according to the reassociation time and then request network access again.

According to the research, the second prior art is mainly insufficient:

1) the broadband PLC can only send the association request frame and the association reply frame in a CSMA time slot based on a beacon period, when the number of the STAs is large, part of the STAs possibly compete for a channel to send the association request frame at the end of the CSMA time slot, and the CCO fails to reply to the association reply frame for the STAs in the beacon period, so that the association request frame can only be replied in the next period. The technology does not consider that the association request frame sent by the STA can be retransmitted if the association request frame sent by the CCO is not received within a certain time, and the CCO may have sent the association reply frame to the STA according to the above-mentioned situation. May cause unnecessary transmission of retransmission of this portion of the association request frame, resulting in spam and resulting in increased system control messages.

2) This technique does not take into account that retransmitted association reply frames may be transmitted in other slots than the CSMA slot, which may cause the STA's association request frame to stop waiting until the next CSMA slot is transmitted, thus increasing retransmission time and hence delay.

Disclosure of Invention

The present invention is directed to solving the above problems of the prior art. An efficient BPLC network networking method is provided. The technical scheme of the invention is as follows:

a high-efficiency BPLC network networking method comprises designing a CCO self-adaptive multicast sending association confirmation frame mechanism and an association request frame self-adaptive waiting retransmission mechanism; in the self-adaptive multicast sending association confirmation frame mechanism, when a plurality of association reply frames are to be sent, one association confirmation multicast frame is used for sending a group of reply messages; in the association request frame self-adaptive retransmission waiting mechanism, an association reply frame which cannot be sent in a CSMA time slot is sent to a CCO node for a period of time, so that the time when an STA retransmits an association request message falls in any time slot of a beacon period, and unnecessary retransmission of the association request frame can be effectively reduced.

Further, the CCO adaptive multicast transmission association acknowledgement frame mechanism includes the following steps:

step 1: starting a neighbor network monitoring timer when a CCO is started, coordinating an internetwork identifier NID and a time slot if an internetwork coordination frame is received within a monitoring time T, networking a single network if the internetwork coordination frame is not received within the monitoring time T, and broadcasting a central beacon in a beacon time slot by the CCO;

step 2: the neighbor node receives the central beacon, checks whether a 'starting association flag bit' of the beacon is 1, prepares to send an association request frame, monitors whether data is transmitted on a bus or not before the station prepares to send the data, if the channel is found to be idle in the monitoring, the STA station directly sends the association request frame to a CCO (central control unit), if the line is found to be busy in the monitoring, the station waits for a delay and then monitors again, if the line is still busy, the waiting is continued to be delayed, if the waiting time n exceeds a threshold value 16, the STA retransmits the association request frame and marks the frame, the time of each time delay is inconsistent, and a delayed value is determined by a truncated binary exponential backoff algorithm; if the STA does not receive the association reply frame within a certain time, waiting for T time to resend the association request frame, and marking the frame;

and step 3: the CCO receives an association request frame sent by a network access application node, inquires STA site information corresponding to the association request frame, performs white list authentication, inquires the number of layers of a site, determines a next hop destination address, if the next hop destination address is a first-level site, the destination address is a local node, if the next hop destination address is a multilayer, the destination address is a PCO corresponding to the lowest level of the request site, and the CCO allocates TEI and time slots for the nodes and stores the TEI and time slots in an association reply frame; the CCO performs association reply on the primary site, and if the CCO finds that the channel is busy when the association reply is sent, the CCO puts an association reply frame into a special association reply queue;

and 4, step 4: detecting the number of associated replies in the queue, if the number is 1, waiting for channel idle unicast to send an associated confirmation message, if the number is more than 1, taking out all the associated messages in the queue, acquiring address information of each node, forming an associated confirmation multicast frame, wherein the length of the associated confirmation multicast frame is less than the length of the maximum frame, otherwise, forming a second multicast frame, the length of the second multicast frame can not be more than the length of the maximum frame, and so on, and sending the second multicast frame to a first-level node when the channel is idle;

and 5: the primary node judges whether the node is a node applying for network access, if so, the network access is successful; if not, the node is the PCO applying for the lowest level of the network access node, the node forms a correlation confirmation frame to the correlation reply frame sent by the node to the node through the CCO and sends the correlation confirmation frame to the next level node, the next level node also judges whether the node is the network access node or not, if not, the node is the second level PCO of the network access node, the node installation address information continues to send the correlation confirmation message to the next level node, and so on until the correlation request node is found, the network access is successful;

step 6: the CCO receives the association request frame sent by the STA, judges whether a retransmission mark exists or not, if so, stops sending the association confirmation frame, only receives the association request frame in the time slot, and takes out the information such as the node ID, the original address and the like to form an association confirmation multicast frame; and multicast sending the association confirmation multicast frame at the time of Tmax. The algorithm for multicast sending the association confirmation multicast frame is consistent with the mechanism for replying the association confirmation frame by self-adaptive multicast;

and 7: and the primary node judges whether the primary node is a node applying for network access, and if so, the network access is successful. If not, the node is the PCO applying for the lowest level of the network access node, and continues to send to the lower level node until the PCO is sent to the network access applying node, and the network access is successful.

Further, before sending the association reply frame, the CCO checks the number of association confirmation frames in its message queue, and if the number is equal to 1, directly sends the association confirmation frame; if the correlation confirmation frame in the cache queue is larger than 1, integrating the correlation confirmation frame in the cache queue, carrying out multicast transmission, and naming the multicast frame as a correlation confirmation multicast frame; the association reply frame sent by the CCO has two frame formats, one is an association confirmation frame, and the other is an association confirmation multicast frame; when the CCO inquires that more than 1 associated confirmation frame is waiting to be sent in the buffer queue of the CCO, the frames are combined into an associated confirmation multicast frame for multicast sending, if the associated confirmation multicast frame is larger than the maximum frame length after the addition of one associated confirmation frame is found in the integration process, the combination is not continued, and the maximum associated confirmation multicast frame is multicast sent.

Further, when the CCO queries the number of the association confirmation messages in its queue, unicasts an association confirmation frame when the number is 1, and when the number is greater than 1, uses an association confirmation multicast frame, which may carry a plurality of association confirmation messages, and proposes an association confirmation multicast frame based on the association confirmation frame, which is modified as follows: 1. the remaining value of the management type field is used to indicate the number of associated acknowledgement messages carried by the frame. 2. And deleting reserved fields in the header of the management message to reduce the length of the frame.

Further, in the association confirmation multicast frame format, deleting a reserved field in a header of a management message; the highest bit of the message type of the association confirmation multicast frame is set to be 1, the association confirmation multicast frame is used when the number of the association confirmation frames is more than 1, the range of 0x1002-0x1400 is used for representing the number of the association confirmation frames in the association confirmation multicast frame, the total number of the stations at most comprises 1022, the range of 0x1401-0x14FF is defined as the reserved part of the number of the association confirmation frames, and different association confirmation multicast frames are distinguished through the destination addresses of different association confirmation messages carried in the association confirmation multicast frame.

Further, the step of adaptively waiting for retransmission of the association request frame specifically includes:

the STA station sends a network access request message and starts a retransmission request frame clock;

after receiving the association request frame, the CCO sends an association reply frame according to a new mechanism of 'CCO self-adaptive multicast reply association confirmation frame';

if the association reply frame is successfully received by the STA in the CSMA time slot, the STA successfully accesses the network, if the association reply frame does not successfully compete to the channel in the CSMA time slot, the STA waits for the next CSMA time slot to preferentially send the association reply frame;

if the network access application station does not receive the association reply frame after the retransmission frame timer overflows and the association request frame can only be retransmitted in the next CSMA time period, waiting for a period of time in the CSMA time slot, wherein the recommended value is half of the length value of the CSMA time period, and judging whether a CCO (communication control entity) sends association reply to the STA.

Further, the retransmission of the association request frame in step 1) may occur as follows:

0-retransmission time too short, falling in the TDMA time slot or the binding CSMA time slot of the current beacon period; 1-the retransmission time falls in the beacon slot of the next beacon period; 2-retransmission time falls in CSMA slot of the next cycle; 3-the retransmission time falls in the TDMA slot and the bonding CSMA slot of the next beacon period; 4-the retransmission time falls after the next beacon slot.

Further, the step 4) waits for retransmission under the following conditions:

if the association reply frame sent by the CCO to the CCO is received, the association request frame does not need to be retransmitted;

if an association confirmation multicast frame with the length not reaching the maximum frame length is received in the waiting time and no association confirmation message sent to the STA exists in the multicast frame, the CCO is indicated to have no association confirmation information for the CCO, and then an association request frame is retransmitted to reapply for network access;

if the association confirmation multicast frame with the maximum frame length is received in the waiting time and the association confirmation message sent to the STA is not in the multicast frame, continuing to monitor until the waiting time is over;

and if the association reply frame sent by the CCO to the CCO is not received within the waiting time, retransmitting an association request frame to reapply for network access.

Further, when the retransmission time is shorter, the time when the STA retransmits the association request frame falls within the TDMA slot, the binding CSMA slot of the current beacon period or the beacon slot of the next beacon period, when the retransmission time is exactly within the CSMA slot of the next beacon period, the STA stops waiting until the next CSMA slot arrives, and cannot compete for the slot immediately at this time, and continues to listen for half of the time of waiting for the entire CSMA slot, and if no association reply frame is sensed, the STA retransmits the association request frame to apply for network entry to the CCO; if the association reply frame from the CCO is received in the interception time, the destination address of the frame is obtained, if the frame is given to the frame, the retransmission mechanism is closed, the association confirmation message of the CCO is received at the moment, the network is successfully accessed, and the association request frame does not need to be retransmitted for network access again. If the association reply frame is sensed but the destination address is not itself, sensing is continued, and if the sensing time reaches half of the CSMA slot, the association request frame is retransmitted.

Further, when the time when the STA retransmits the association request frame falls in the CSMA time slot of the next beacon period, firstly judging whether the time falls in the first half section or the second half section of the CSMA time slot, if the time falls in the first half section, then, firstly, monitoring whether a CCO transmits the association request frame to the STA, and if the time does not detect the association reply frame transmitted by the CCO to the STA at the half position of the CSMA time slot, then, again competing and transmitting the association request frame at the half time of the CSMA time; if the association reply sent to the self is intercepted from the CSMA to the CSMA half time slot, the network access is successful, and the association request frame does not need to be retransmitted;

when the time when the STA retransmits the association request frame falls in the TDMA and binding CSMA time slots of the next beacon period, the beacon period is not processed, and the processing is performed in the next beacon period;

when the time when the STA retransmits the association request frame falls in another beacon period, it needs to stop waiting until the CSMA slot is processed.

The invention has the following advantages and beneficial effects:

the innovation of the invention is mainly made by the combination of step 4 as described in claim 2, the features of claim 5 and step 4) as described in claim 6. The method of claim 2, wherein step 4 is to solve the problem that the BPLC network CCO has a large message overhead and a large delay when multiple associated acknowledgement frames are to be sent; claim 5 is proposed to avoid adding extra fields to a new multicast frame type proposed by step 4 of claim 2; step 4) recited in claim 6 is proposed to solve the problem that the association request frame is unnecessarily retransmitted, which still exists in the new networking method proposed by the present patent based on step 4 recited in claim 2. Therefore, the patent proposes a BPLC network high-efficiency networking method based on the above three innovation points.

The advantage of step 4 in claim 2 is that by combining the association confirmation messages in the message queue reasonably, and sending a group of reply messages by using an association confirmation multicast frame, the number of messages sent in the contention time slot is reduced, and the successful network access speed of the network access application node is increased. The advantage of claim 5 is that it proposes a range of 0x1002-0x1400 with a management message type field of 2 bytes size in the management message header (where 0x0000-0x0050 is already occupied by association request messages and association acknowledgement messages) to indicate the number of association acknowledgement frames in association acknowledgement multicast frames (the number of aggregated sites contains 1022 at most), so that it is not necessary to add a new field to indicate the number of association acknowledgement frames in association acknowledgement multicast frames. Finally, the overhead of the control message is further reduced by deleting the reserved field in the association confirmation multicast frame. The advantage of step 4) as recited in claim 6 is that by sending the CCO node an association reply frame which was not sent in a CSMA slot for a certain time, the time when the STA retransmits the association request message falls in any slot of the beacon period can effectively reduce unnecessary retransmission of the association request frame.

Drawings

FIG. 1 is a diagram of a multi-user broadband power line communication network in the prior art;

FIG. 2 is a diagram of a wideband power line carrier communication network protocol stack level division;

FIG. 3 is a broadband power line carrier communication network topology;

FIG. 4 is a flow diagram of an associated network frame interaction;

FIG. 5 is a schematic diagram of time slot division;

FIG. 6 is a schematic diagram of association messaging;

FIG. 7 is a large scale site schematic;

fig. 8 is a schematic diagram of delayed transmission of an association acknowledgement frame;

fig. 9 is a schematic diagram of a retransmission association request frame;

fig. 10 is a schematic diagram of an association acknowledgement multicast frame with a less than maximum frame length;

fig. 11 is a diagram illustrating that the association confirms that the multicast frame has reached the maximum frame length;

FIG. 12 is a flow diagram of an adaptive multicast access protocol;

FIG. 13 is a flowchart of the operation of the association request frame adaptive retransmission waiting mechanism;

FIG. 14 is a flowchart of the operation of a specific embodiment of the new mechanism CCO;

fig. 15 is a flowchart of the operation of the STA embodiment in the new scheme;

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail and clearly with reference to the accompanying drawings. The described embodiments are only some of the embodiments of the present invention.

The technical scheme for solving the technical problems is as follows:

abbreviations and Key terms of the invention

1.1.1 BPLC protocol stack structure

The broadband power line carrier communication network protocol stack defines 3 layers of a physical layer, a data link layer and an application layer based on a standard Open System Interconnection (OSI) seven-layer model, and the basic structure is shown in fig. 2. Wherein the data link layer is divided into a network management sublayer and a medium access control sublayer (MAC sublayer). The data link layer directly provides transmission service for the application layer, and can also be extended to interface with standard TCP/IP to realize standard IP network communication.

1.1.2 networking Process for BPLC network

The broadband power line carrier communication network topological diagram is shown in fig. 3, and the networking process of the BPLC mainly includes three parts, namely multi-network inter-network coordination, single-network networking and network maintenance.

Multi-network inter-network coordination: the specific flow of the multi-network inter-network coordination is as follows:

1) after the CCO is started, network monitoring is performed for a period of time, and whether a working broadband power line carrier communication network exists around the CCO is judged. For the broadband power line carrier communication network which is already in operation, the inter-network coordination frame should be periodically sent so that other CCOs which are powered on later can monitor the inter-network coordination frame.

2) If the inter-network coordination frame of the neighbor network is received within the CCO monitoring time, negotiation is required to be performed according to a certain priority principle according to information such as SNID and time slot carried in the inter-network coordination frame; if no inter-network coordination frame is monitored, the CCO can work independently.

3) And then, carrying out bandwidth coordination, and staggering the beacon time slots of different networks as orderly as possible according to a bandwidth negotiation principle, so that not only is the collision of the beacon time slots ensured, but also the periodicity of beacon time slot transmission is ensured.

Single-network networking: in order to ensure the reliability of the route establishment and data transmission of the broadband PLC network, the broadband PLC network can carry out network networking. The process is as follows:

1) and after the CCO is electrified, coordinating time slots and network identifiers among networks, and performing single-network networking after the coordination is successful.

2) The CCO starts sending a central beacon in the beacon slot, and stations receiving the central beacon request for entry by sending an association request frame in the CSMA slot.

3) And the STA retransmits the association request frame if not receiving the association confirmation frame within a period of time after sending the association request frame.

4) And the CCO authenticates the site requesting network access through the white list, and after the authentication is successful, a processing result is sent to the STA site requesting network access through an association confirmation frame to represent that the node successfully accesses the network.

5) After the first-level node successfully accesses the network, the CCO schedules a beacon time slot for the first-level node to send a discovery beacon, and the sending of the discovery beacon can trigger a second-level site around a new network access site to initiate a request for associating with the network access.

6) The above-mentioned steps are circulated, so that the STA station of the highest hierarchy furthest away from the CCO joins the network.

Associated ingress frame interaction is shown in fig. 4:

1.1.3 BPLC channel access mechanism

The broadband power line carrier communication network uses a channel access mechanism based on a beacon frame, the CCO periodically transmits the beacon frame, and the beacon frame comprises planning information of beacon time slots, TDMA time slots, CSMA time slots, binding CSMA time slots and the like in a beacon period allocated by the CCO. The sub-nodes in the broadband power line carrier communication network have to follow the time slot allocated by the CCO for channel access. The slot division of the beacon period is shown in fig. 5:

generally, beacon time slots, TDMA time slots and other time slots explicitly allocated to the CCO or a specific STA are collectively referred to as non-contention time slots (TDMA time slots), and the management algorithm for the time slots in the beacon must be uniform. The CCO allocates the time slots in the beacon period, fills the time slot allocation entries in the beacon according to a uniform algorithm, and notifies the PCO, the STA and other stations through beacon transmission; the CSMA slot and the binding CSMA slot, etc. are slots not designated by a user, and slots to be used by STAs having a need for contention are collectively referred to as contention slots (CSMA slots). When the CCO plans the time slot, it can allocate the binding CSMA time slot according to the service requirement, and the time slot is occupied by some service alone, and all STAs related to the service can compete to send the frame of the service in the binding CSMA time slot.

1.1.4 CSMA slots

Since the invention only relates to CSMA slots, only CSMA slots will be described here. The CSMA slot is not a slot explicitly allocated to a CCO or a specific STA, unlike a beacon slot and a TDMA slot, but a slot that can be commonly occupied by various station types. In the CSMA time slot (including the binding CSMA), stations must contend through a channel, and after collision avoidance, can occupy the channel to transmit a frame.

Frames sent in a CSMA slot must be guaranteed to be able to transmit in the corresponding CSMA slot, and cannot span the slot. Especially ensuring that it cannot span into non-contention slots such as beacon slots and TDMA slots. When channel competition is carried out in CSMA time slot, basic conflict judgment and avoidance are needed, and the channel state is further prejudged through VCS mechanism, and the corresponding frame can be sent only after the channel is judged to be idle.

In a CSMA slot, a plurality of different types of nodes are allowed to transmit messages, and a plurality of control frames such as an association request frame, an association confirmation frame, and the like are allowed for uplink and downlink, but these frames all require contention for transmission, so CSMA makes the slot a contention slot.

1.2 basic assumptions of the invention

1) The networking is performed in a single BPLC network consisting of one CCO and multiple STAs.

2) The SNID negotiation between the network CCO devices is completed, the SNID of each network is determined, and the independent and stable networking of each broadband communication network is ensured.

3) STA equipment in the broadband power line network has a network access waiting time threshold.

4) And if the non-network-accessing station in the broadband power line network does not receive the association confirmation frame within a period of time after the network access application, retransmitting the association request frame.

5) The association confirm frame, the association request frame, and the association confirm multicast frame may be transmitted only in the CSMA slot.

6) Each association reply frame cannot be larger than the maximum frame length specified by the QGDW 11612.42-2016 low-voltage power line broadband power line carrier communication interconnection technical specification.

7) When the CCO receives the STA network access request frame and prepares to send the association reply frame in the CSMA time slot, if the association reply frame is not sent because of no resource competition or no available time slot in the beacon period, the CCO must wait for the next beacon period and then send the association reply frame to the STA.

1.3 technical problem to be solved by the invention

1.3.1 there is control overhead and time redundancy in the association acknowledgement frame transmission mechanism

According to the existing broadband power line carrier communication network technology, in the networking process of a BPLC network, after a central coordinator CCO broadcasts a central beacon to send networking information, the CCO possibly receives association request frames sent by a plurality of non-networked STAs (the frames are used for non-networked nodes to apply for networking); the CCO needs to reply association acknowledgement frames one by one to the association request frames in a unicast manner; the association request frame and the association confirmation frame are both transmitted in the CSMA slot in the beacon period.

A large number of association request frames need to be sent in the same time slot in a competitive manner in the same scale, which occupies a large amount of channel resources, so that the system control overhead is large, and channels of the BPLC network are crowded in the CSMA period; in a severe case, some STAs may not receive the association acknowledgement frame replied by the CCO in the beacon period after sending the association request frame, as shown in fig. 7, a total of 10 STAs send uplink association request frames, and only 8 STAs successfully receive the association acknowledgement downlink frame sent by the CCO. The reason is that the association request frame and the association confirmation frame are both sent in a contention manner, the STA detects whether the channel is idle after sending the association request frame and the CCO receives the association request frame, at this time, because other STAs continue to send the association request frame or the association confirmation frame replied by the CCO to other STAs is still sent in the channel, the channel is busy, the CCO does not compete for the channel, or there is not enough time for the CCO to send the association confirmation frame at the end of the CSMA period, in both cases, the CCO has to temporarily store the association confirmation frame in the message queue. During the period of the association confirmation frame being temporarily stored in the message queue, if a new association confirmation frame is to be sent, the new association confirmation frame is also temporarily stored in the message queue, and at this time, a plurality of association confirmation frames to be sent exist in the message queue at the same time.

Therefore, if one association confirmation frame can be sent and multiple network access application nodes can be replied at the same time, the mechanism that the CCO replies the association confirmation frame to the network access application nodes one by one adopted by the existing scheme has the problems that the relative control overhead (mainly referred to as communication overhead) is relatively larger and the time consumed for network access of the nodes is relatively more compared with the mechanism that the nodes are replied once, and needs to be solved.

1.3.2 Association request frame retransmission mechanism there is control overhead redundancy

According to the existing broadband power line carrier communication network technology, in the networking process, after the STA receives a central beacon sent by a CCO, an association request frame is sent to the CCO to apply for network access; after receiving the request frame, the CCO immediately replies an association confirmation frame to the STA; both the association request frame and the association confirmation frame are sent in CSMA contention slots, as shown in fig. 5. If the channel contention is severe in the CSMA period, or if the STA transmits the association request frame at a later time of the current CSMA slot, the CCO may not reply to the association request frame transmitted by the STA in the current CSMA period because of failing to contend for the channel, and may only wait until the CSMA period of the next beacon period, as shown in fig. 8.

According to the second prior art, after sending the association request frame, the STA starts a timer, and if the association reply frame sent by the CCO is not received within the timeout retransmission threshold, the STA retransmits the association request frame. If the timeout retransmission time is in the CSMA time slot, the direct contention transmission is performed, and if the timeout retransmission time is not in the CSMA time slot, the direct contention transmission is performed until the next CSMA time slot comes, and the direct contention transmission is performed, as shown in FIG. 9.

According to the above association request frame retransmission mechanism, when the CCO prepares to transmit the association reply frame at the start time of the next CSMA period, the corresponding STA also prepares to transmit the association request frame again at the start time of the next CSMA period, which may cause the retransmitted association request frame to become unnecessary, resulting in redundant control overhead; because: the CCO transmits an association reply frame to the STA even if it does not retransmit the association request frame.

1.4 New mechanism proposed by the invention

In order to solve the problem in section 1.3, the invention provides a novel efficient broadband PLC network networking method. The method is characterized in that: the adaptive multicast sends an association confirmation frame and an association request frame to wait for retransmission adaptively. The unicast transmission of reply messages can bring a lot of control overhead, and when a new mechanism of the self-adaptive multicast transmission of the associated acknowledgement frame is provided with a plurality of associated reply frames to be transmitted, one frame is used for transmitting a group of reply messages, so that the control overhead of the BPLC network can be reduced; the new mechanism of "association request frame adaptive wait for retransmission" can reduce unnecessary retransmission of association request frames by sending association reply frames to the CCO node for a period of time.

1.4.1 New mechanism 1-adaptive multicast reply association acknowledgement frame

The problem that the number of the associated acknowledgement frames and the end-to-end delay are large in section 1.3.1 is solved. The new mechanism of 'CCO adaptive multicast reply association acknowledgement frame' considers that the broadband PLC is in a tree topology, and some STA sub-stations are mounted under the PCO, which means that the higher the hierarchy is, the more the stations are likely to be. Then there is a high possibility that the association confirmation messages sent by a plurality of to-be-networked stations are put into the cache queue by the CCO and are not replied in time, so a CCO adaptive multicast reply association confirmation frame mechanism is proposed, and an association confirmation multicast frame used when the number of association confirmation frames is greater than 1 is proposed. The basic idea is as follows:

when the CCO sends the association confirmation frame, if the channel is found to be busy, the CCO stores the association confirmation frame in the association reply queue and waits for the channel to be idle for sending. At this time, there may be a plurality of associated acknowledgement frames in the message queue, if the associated acknowledgement frames in the message queue can be "combined", because the associated reply frame has the maximum frame length, the combined frame after integration must also be smaller than the maximum frame length, if it is found in the combining process that adding one associated request frame makes the whole combined frame larger than the maximum frame length, at this time, it cannot be added, and it is necessary to send the combined frame, then recombine and send it. A plurality of associated confirmation frames form a frame multicast transmission, so that the interception times can be greatly reduced, and the frame transmission quantity is reduced. Meanwhile, fields such as a frame header and the like which are shared can be saved, and the network control overhead is reduced. The idea of solving the problem in section 1.3.1 is that the CCO checks the number of the associated acknowledgement frames in its message queue before sending the associated reply frame, and if the number is equal to 1, directly sends the associated acknowledgement frame. And if the correlation confirmation frame in the buffer queue is larger than 1, integrating the correlation confirmation frame in the buffer queue, carrying out multicast transmission, and naming the multicast frame as a correlation confirmation multicast frame. Therefore, the association reply frame sent by the CCO has two frame formats, one is an association confirmation frame and the other is an association confirmation multicast frame. As shown in fig. 8, when the CCO queries that there are more than 1 associated acknowledgement frames waiting to be sent in its own buffer queue, these frames are combined into an associated acknowledgement frame for multicast transmission. If the association confirmation multicast frame is larger than the maximum frame length after the association confirmation frame is added in the integration process, the combination is not continued, and the maximum association confirmation multicast frame is multicast-transmitted. Fig. 10 is a schematic diagram of association confirmation frames with a maximum combination number of 5, and fig. 11 is a schematic diagram of association confirmation frames with a maximum combination number exceeding.

The basic principle of the mechanism is as follows: the CCO inquires the number of the associated confirmation messages in the queue of the CCO, unicasts the associated confirmation frames when the number is 1, and uses the associated confirmation multicast frames when the number is more than 1 to more reasonably send the associated confirmation frames, thereby increasing the network access success rate of the nodes and simultaneously reducing the network access delay and the control overhead. The association confirmation multicast frame itself may carry a plurality of association confirmation messages, so the association confirmation multicast frame is proposed based on the association confirmation frame, which is modified as follows: 1. the remaining value of the management type field is used to indicate the number of associated acknowledgement messages carried by the frame. 2. And deleting reserved fields in the header of the management message to reduce the length of the frame.

The flow of the mechanism for replying the association confirmation frame by the CCO self-adaptive multicast is as follows:

step 1: when the CCO is started, a neighbor network monitoring timer is started, and if an internetwork coordination frame is received within the monitoring time T, the internetwork Network Identification (NID) and the time slot are coordinated. And if the inter-network coordination frame is not received within the interception time T, performing single-network networking. The CCO broadcasts a central beacon at the beacon slot.

Step 2: the neighbor node receives the central beacon, checks whether the 'association starting flag bit' of the beacon is 1, prepares to send an association request frame, and monitors whether data is transmitted on the bus (whether the line is busy) before the station prepares to send the association request frame. If the channel is found to be idle in the listening, the STA station directly sends an association request frame to the CCO. If the line is busy during the monitoring, the monitoring is carried out again after waiting for a delay, if the line is still busy, the delay waiting is continued, and if the waiting time n exceeds the threshold value 16, the STA retransmits the association request frame and marks the frame. And determining a delay value by a truncated binary exponential back-off algorithm when the time of each time delay is inconsistent. And if the STA does not receive the association reply frame within a certain time, waiting for T time to resend the association request frame, and marking the frame.

And step 3: and the CCO receives an association request frame sent by the network access application node, inquires the STA site information corresponding to the association request frame and performs white list authentication. And the CCO inquires the layer number of the station, determines the destination address of the next hop, if the station is a primary station, the destination address is the node, and if the station is a multi-layer station, the destination address is the PCO of the lowest level corresponding to the requesting station. The CCO allocates TEIs and time slots for the nodes, which are stored in the association reply frame. And the CCO performs association reply on the primary station, and if the CCO finds that the channel is busy when the association reply is sent, the CCO puts an association reply frame into a special association reply queue.

And 4, step 4: and detecting the number of the associated replies in the queue, and if the number of the associated replies in the queue is 1, waiting for the channel idle unicast to send an associated confirmation message. If the length of the associated confirmed multicast frame is less than the maximum frame length, otherwise, a second multicast frame is formed, and the second multicast frame can not be greater than the maximum frame length, and so on, and is sent to the first-level node when the channel is idle.

And 5: and the primary node judges whether the primary node is a node applying for network access, and if so, the network access is successful. If not, the node is the PCO applying for the lowest level of the network access node, the node forms a correlation confirmation frame to the correlation reply frame sent by the node to the node through the CCO and sends the correlation confirmation frame to the next level node, the next level node also judges whether the node is the network access node or not, if not, the node is the second level PCO of the network access node, the node installation address information continues to send the correlation confirmation message to the next level node, and so on until the correlation request node is found, the network access is successful.

Step 6: the CCO receives the association request frame sent by the STA, judges whether a retransmission mark exists or not, stops sending the association confirmation frame if the retransmission mark exists, only receives the association request frame in the time slot, and takes out the information such as the node ID, the original address and the like to form an association confirmation multicast frame. And multicast sending the association confirmation multicast frame at the time of Tmax. The algorithm for multicast sending the association confirmation multicast frame is consistent with the mechanism for replying the association confirmation frame by the self-adaptive multicast.

And 7: and the primary node judges whether the primary node is a node applying for network access, and if so, the network access is successful. If not, the node is the PCO applying for the lowest level of the network access node, and continues to send to the lower level node until the PCO is sent to the network access applying node, and the network access is successful. The process is consistent with the process that whether the node applies for the network access is judged by the node in the self-adaptive multicast reply association confirmation frame mechanism.

The flow of the adaptive multicast network access protocol is shown in fig. 12:

associating the acknowledgement multicast frame:

table 1 is a table of frame formats associated with the primary frame field of the acknowledgment frame. In the broadband PLC network, the association acknowledgement packet is a management message packet, and the header of the packet has a management message type field with a size of 2 bytes, for example, table 2 is the type of the management message, where the range of 0x0000-0x0050 is already used by other association message packet parts, in order to distinguish from the existing management message types and to include the number information of association acknowledgement frames on the basis of not adding new fields, the highest bit of the message type of the newly proposed association acknowledgement multicast frame is set to 1. When the number of the association confirmation frames is greater than 1, the association confirmation multicast frame is used, so that the range of 0x1002 to 0x1400 is used to represent the number of the association confirmation frames in the association confirmation multicast frame (the total station number contains 1022 stations at most), the range of 0x1401 to 0x14FF is defined as a reserved part of the number of the association confirmation frames, the type of the association confirmation multicast frame management message is shown in table 3, and the format of the association confirmation multicast frame is shown in table 4. Wherein the reserved field has no substantial effect on the newly proposed association confirmation multicast frame, and is therefore deleted from the perspective of reducing network overhead; considering the condition that the management type fields carrying the same number of associated acknowledgement multicast frames are the same, the mechanism can distinguish different associated acknowledgement multicast frames through the destination addresses of different associated acknowledgement messages carried in the associated acknowledgement multicast frames; the association confirms that the multicast frame cannot exceed the maximum frame length allowed by the prior art two.

Table 1 associated acknowledgement frame table

Table 2 management message types

Managing message names	Managing message type identifiers
		Association request	0x0000
Association confirmation	0x0001
		Association summary indication	0x0002
Proxy change request	0x0003
		Proxy change validation	0x0004
Proxy change validation	0x0005
		Offline indication	0x0006
Heartbeat detection	0x0007
		Discovery list	0x0008
Communication success rate reporting	0x0009
		Network conflict reporting	0x000A
Zero crossing NTB acquisition indication	0x000B
		Zero crossing NTB reporting	0x000C
Retention	0x000D-0x004F
		Routing requests	0x0050

Table 3 new mechanism 1 management message types

Managing message names	Managing message type identifiers
		Association confirmation multicast	0x1002-0x1400
Retention	0x1401-0x14FF

Table 4 association acknowledgement multicast frame

1.4.2 New mechanism 2-Association request frame Adaptation waiting for retransmission

The new mechanism of 'association request frame self-adapting waiting for retransmission' mainly acts on the period that when a single network is organized, an STA sends an association request frame to a CCO to request network access, and the CCO replies an association request frame to a station to be accessed to the network. The basic idea is as follows:

for the unreasonable issue of the association acknowledgement frame retransmission mechanism described in section 1.3.2, considering the requirement of prior art 2, the STA in the CSMA slot of the next cycle may retransmit the association request frame. However, the reason why the association reply frame is not received may be that the CCO does not contend for the channel in the CSMA slot of the last beacon slot and transmits in the CSMA slot of the next beacon period, and it is not because the CCO does not transmit the association reply frame to the STA, which causes the STA to retransmit the association request frame, so if it is ensured that the association reply frame that is not transmitted in the last CSMA period is transmitted before the retransmitted association request frame, and the STA receives the corresponding association reply frame, the association request frame is not retransmitted, and thus the association request frame is transmitted less than the original mechanism, and the control overhead of the network is effectively reduced.

The STA does not receive the reply message within a period of time after the STA sends the request message, the STA can resend the request message in the next beacon period, the request message can be resent in a period of time except CSMA, channel collision can be generated when the request message is resent in CSMA, and the delay can be increased due to the increase of the resending time, so that the adaptive adjustment and control mechanism of the resending time of the association request frame is provided, and the unsent association reply frame in the previous period can be preferentially sent in a CSMA competition time slot; meanwhile, the STA continuously monitors a period of time, and if the association reply frame sent to the STA by the CCO is not monitored, the association request frame is retransmitted to request network access. The "association request frame adaptive wait for retransmission mechanism" mainly operates as follows:

1) the STA station sends a network access request message and starts a retransmission request frame clock, and the following situations may occur in the retransmission association request frame:

2) After receiving the association request frame, the CCO sends an association reply frame according to a new mechanism of 'CCO self-adaptive multicast reply association confirmation frame'.

3) If the association reply frame is successfully received by the STA in the CSMA time slot, the STA successfully accesses the network. If the association reply frame does not successfully contend for the channel in the CSMA slot, wait until the next CSMA slot to transmit the association reply frame preferentially.

4) If the network access application station does not receive the association reply frame after the retransmission frame timer overflows and the association request frame can only be retransmitted in the next CSMA time period, waiting for a period of time in the CSMA time slot, wherein the recommended value is half of the length value of the CSMA time period, and judging whether a CCO (communication control entity) sends association reply to the STA. There are several situations for waiting for retransmission:

(1) if the association reply frame sent by the CCO to the CCO is received, the association request frame does not need to be retransmitted.

(2) If the association confirmation multicast frame with the length not reaching the maximum frame length is received in the waiting time and the association confirmation message sent to the STA is not in the multicast frame, the association confirmation message sent to the STA is indicated to be not sent to the CCO, and then an association request frame is retransmitted to reapply for network access.

(3) If the association confirmation multicast frame with the maximum frame length is received in the waiting time and the multicast frame has no association confirmation message sent to the STA, the monitoring is required to be continued until the waiting time is over.

(4) And if the association reply frame sent by the CCO to the CCO is not received within the waiting time, retransmitting an association request frame to reapply for network access.

The timing of each retransmission request frame is described in detail below:

(1) when the retransmission time is shorter, the time when the STA retransmits the association request frame falls in the TDMA time slot of the current beacon period, the binding CSMA time slot or the beacon time slot of the next beacon period, when the retransmission time just falls in the CSMA time slot of the next beacon period, the STA stops waiting until the next CSMA time slot arrives, cannot compete for the time slot immediately at the moment, continues to monitor the time for waiting for half of the whole CSMA time slot, and if any association reply frame is not monitored. The contention retransmission association request frame applies for network entry to the CCO. If the association reply frame from the CCO is received in the interception time, the destination address of the frame is obtained, if the frame is given to the frame, the retransmission mechanism is closed, the association confirmation message of the CCO is received at the moment, the network is successfully accessed, and the association request frame does not need to be retransmitted for network access again. If the association reply frame is sensed but the destination address is not itself, sensing is continued, and if the sensing time reaches half of the CSMA slot, the association request frame is retransmitted.

(2) Similarly, when the time when the STA retransmits the association request frame falls in the CSMA time slot of the next beacon period, firstly judging whether the time falls in the first half section or the second half section of the CSMA time slot, if the time falls in the first half section, firstly sensing whether a CCO (central control unit) transmits the association request frame to the STA, and if the time does not sense the association reply frame transmitted by the CCO to the STA at the half part of the CSMA time slot, re-competing and transmitting the association request frame at the half time of the CSMA time; if the association reply sent to the self is sensed from the half time slot from the beginning of CSMA, the network access is successful, and the association request frame does not need to be retransmitted.

(3) When the time when the STA retransmits the association request frame falls in the TDMA and binding CSMA time slots of the next beacon period, the beacon period does not process, and the processing mode is the same as the processing mode (1) in the next beacon period.

(4) When the time when the STA retransmits the association request frame falls in another beacon period, the STA needs to stop waiting for the CSMA slot to perform processing, which is similar to the processing method (1).

The work flow of the "association request frame adaptive retransmission waiting mechanism" is shown in fig. 13:

1.5 specific embodiments for the implementation of the technique of the present invention

In the broadband power line carrier networking process, a mode of sending the association confirmation frames one by one is adopted when the CCO sends the association confirmation frames, and when the network scale is large, the CCO carries out association confirmation reply one by one on the network access application nodes, so that the association confirmation frames cannot be sent in time in a CCO cache queue, and time delay and networking control overhead are increased.

In the prior art, retransmission time of an association request frame is not specified specifically, if a CCO does not receive an association confirmation message within a period of time after the association request frame is sent, the association request frame is considered to be retransmitted, and if the retransmission time of the association request frame falls in a time slot outside a CSMA, the association request frame is delayed to be retransmitted to the next CSMA time slot, so that time delay is increased; even in CSMA transmission, considering the case where the association reply frame of the CCO reply may have to be transmitted in the next CSMA slot since it does not compete for the channel in the last CSMA slot, there is no need to retransmit the association request frame, which, if transmitted, inevitably increases the control overhead of the network.

The invention provides a novel method for efficiently networking a broadband PLC network, which carries out multicast transmission on an association confirmation frame and optimizes and stipulates the retransmission time of an association request frame under a single-network environment.

The main operation of the new process is as follows:

1) the PLC equipment is initialized firstly, and the CCO equipment and the STA equipment are powered on;

2) under the single-network environment, the CCO broadcasts a central beacon frame to initiate a single-network networking process;

3) the STA equipment starts to send an association request frame after receiving the beacon frame;

4) after receiving the association request frame, the CCO adaptively sends an association reply frame to the primary site according to a CCO adaptive multicast reply association confirmation frame mechanism.

5) The STA does not receive the association confirmation frame or the association confirmation multicast frame in a period of time, and retransmits the association request frame to the CCO according to an 'association request frame adaptive retransmission waiting mechanism'.

6) And the STA receives the association confirmation frame or the association confirmation frame, and networking is successful.

Fig. 14 shows a flow of the CCO after receiving an association request frame sent or forwarded by the primary station:

the example of the procedure in which the STA does not receive the association reply frame sent by the CCO for a period of time as shown in fig. 15 describes:

1.6 the beneficial effects brought by the technical scheme of the invention

The beneficial effects brought by the technical scheme of the invention are mainly reflected in the following aspects:

1) the invention reduces the control overhead of only one frame from the control overhead of a plurality of associated confirmation frames to the control overhead of only one frame, thereby reducing the control overhead and being beneficial to reducing the networking time delay.

2) The invention can adaptively wait for retransmission of the association request frame, can effectively reduce unnecessary retransmission of the association request frame, is beneficial to reducing control overhead and improves the efficiency of the networking method.

1.7 technical Key points and points to be protected of the invention

The technical key points and points to be protected of the invention are as follows:

(1) the new mechanism 1-CCO adaptive multicast replies to the association acknowledgement frame mechanism.

(2) New mechanism 2-association request frame adaptation wait for retransmission mechanism.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above examples are to be construed as merely illustrative and not limitative of the remainder of the disclosure. After reading the description of the invention, the skilled person can make various changes or modifications to the invention, and these equivalent changes and modifications also fall into the scope of the invention defined by the claims.

Claims

1. A high-efficiency BPLC network networking method is characterized by comprising the steps of designing a CCO self-adaptive multicast sending association confirmation frame mechanism and an association request frame self-adaptive waiting retransmission mechanism; in the self-adaptive multicast sending association confirmation frame mechanism, when a plurality of association reply frames are to be sent, one association confirmation multicast frame is used for sending a group of reply messages; in the association request frame self-adaptive retransmission waiting mechanism, an association reply frame which cannot be sent in a CSMA time slot is sent to a CCO node for a period of time, so that the time when an STA retransmits an association request message falls in any time slot of a beacon period, and unnecessary retransmission of the association request frame can be effectively reduced.

2. The method of claim 1, wherein the BPLC network comprises:

the CCO adaptive multicast sending association acknowledgement frame mechanism comprises the following steps:

3. The method of claim 2, wherein;

before sending the association reply frame, the CCO checks the number of association confirmation frames in the message queue of the CCO, and if the number is equal to 1, the CCO directly sends the association confirmation frames; if the correlation confirmation frame in the cache queue is larger than 1, integrating the correlation confirmation frame in the cache queue, carrying out multicast transmission, and naming the multicast frame as a correlation confirmation multicast frame; the association reply frame sent by the CCO has two frame formats, one is an association confirmation frame, and the other is an association confirmation multicast frame; when the CCO inquires that more than 1 associated confirmation frame is waiting to be sent in the buffer queue of the CCO, the frames are combined into an associated confirmation multicast frame for multicast sending, if the associated confirmation multicast frame is larger than the maximum frame length after the addition of one associated confirmation frame is found in the integration process, the combination is not continued, and the maximum associated confirmation multicast frame is multicast sent.

4. The efficient BPLC network networking method according to claim 3, wherein when the CCO queries the number of the associated acknowledgement messages in its queue, unicasts the associated acknowledgement frame when the number is 1, and when the number is greater than 1, uses the associated acknowledgement multicast frame, the associated acknowledgement multicast frame itself can carry multiple associated acknowledgement messages, proposes the associated acknowledgement multicast frame based on the associated acknowledgement frame, and its modification is as follows: 1. using the remaining value of the management type field to represent the number of the associated confirmation messages carried by the frame; 2. and deleting reserved fields in the header of the management message to reduce the length of the frame.

5. The efficient BPLC network networking method of claim 3, wherein: deleting reserved fields in a header of a management message in the correlation confirmation multicast frame format; the highest bit of the message type of the association confirmation multicast frame is set to be 1, the association confirmation multicast frame is used when the number of the association confirmation frames is more than 1, the range of 0x1002-0x1400 is used for representing the number of the association confirmation frames in the association confirmation multicast frame, the total number of the stations at most comprises 1022, the range of 0x1401-0x14FF is defined as the reserved part of the number of the association confirmation frames, and different association confirmation multicast frames are distinguished through the destination addresses of different association confirmation messages carried in the association confirmation multicast frame.

6. The method according to any of claims 1-5, wherein said step of associating a requested frame adaptive retransmission waiting mechanism specifically comprises:

1) the STA station sends a network access request message and starts a retransmission request frame clock;

2) after receiving the association request frame, the CCO sends an association reply frame according to a new mechanism of 'CCO self-adaptive multicast reply association confirmation frame';

3) if the association reply frame is successfully received by the STA in the CSMA time slot, the STA successfully accesses the network, if the association reply frame does not successfully compete to the channel in the CSMA time slot, the STA waits for the next CSMA time slot to preferentially send the association reply frame;

4) if the network access application station does not receive the association reply frame after the retransmission frame timer overflows and the association request frame can only be retransmitted in the next CSMA time period, waiting for a period of time in the CSMA time slot, wherein the recommended value is half of the length value of the CSMA time period, and judging whether a CCO (communication control entity) sends association reply to the STA.

7. The method as claimed in claim 6, wherein the retransmission of the association request frame in step 1) is performed in the following manners:

8. The method of claim 6, wherein: the step 4) waits for retransmission under the following conditions:

(1) if the association reply frame sent by the CCO to the CCO is received, the association request frame does not need to be retransmitted;

(2) if an association confirmation multicast frame with the length not reaching the maximum frame length is received in the waiting time and no association confirmation message sent to the STA exists in the multicast frame, the CCO is indicated to have no association confirmation information for the CCO, and then an association request frame is retransmitted to reapply for network access;

(3) if the association confirmation multicast frame with the maximum frame length is received in the waiting time and the association confirmation message sent to the STA is not in the multicast frame, continuing to monitor until the waiting time is over;

9. The method of claim 8, wherein the BPLC network comprises:

when the time when the STA retransmits the association request frame falls in the CSMA time slot of the next beacon period, firstly judging whether the time falls in the first half section or the second half section of the CSMA time slot, if the time falls in the first half section, then, similarly, firstly monitoring whether a CCO transmits the association request frame to the STA, and if the time does not detect the association reply frame transmitted to the STA by the CCO, then, again contending to transmit the association request frame at the half time of the CSMA time slot; if the association reply sent to the self is intercepted from the CSMA to the CSMA half time slot, the network access is successful, and the association request frame does not need to be retransmitted;