CN107071925B - A kind of broadcast channel method for reliable transmission under CSMA/CA mechanism - Google Patents
A kind of broadcast channel method for reliable transmission under CSMA/CA mechanism Download PDFInfo
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- CN107071925B CN107071925B CN201710255924.XA CN201710255924A CN107071925B CN 107071925 B CN107071925 B CN 107071925B CN 201710255924 A CN201710255924 A CN 201710255924A CN 107071925 B CN107071925 B CN 107071925B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W74/00—Wireless channel access
- H04W74/08—Non-scheduled access, e.g. ALOHA
- H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
- H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
- H04L1/1867—Arrangements specially adapted for the transmitter end
- H04L1/188—Time-out mechanisms
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The invention discloses the broadcast channel method for reliable transmission under a kind of CSMA/CA mechanism, after node receives the broadcast frame of neighbor node transmission, if the new broadcast frame of neighbor node transmission, the broadcast frame new to the neighbor node request retransmission are not received after sending the period thresholding of broadcast frame by the neighbor node yet.The present invention solves the problems, such as broadcast frame loss, it copes in the case that network capacity becomes larger, neighbor node increases within the scope of coverage, frame loss is broadcasted to network fast convergence and routing update work bring pressure, especially effect is more prominent in multichannel ad hoc network and Mesh network.
Description
Technical field
The present invention relates to cordless communication network technical fields, more particularly to the broadcast channel under a kind of CSMA/CA mechanism
Method for reliable transmission.
Background technique
Broadcast frame is considerable maintenance mechanism within a wireless communication network, and mobile node can be allowed to know depositing for network
Entering the basic parameter of network added by acquisition, the information of oneself is broadcasted to neighbor node.
Under CSMA/CA mechanism, when a node will send broadcast frame, busy monitoring first is carried out to channel, such as
Fruit listen to channel be it is not busy, then wait for a period of time, if listened to if channel is the free time in this period,
It then randomly chooses a timeslice in a prior defined time window to continue to listen to the busy of channel, if at this
Between in piece, channel is always idle, then just sending broadcast frame;If channel is busy, that is, channel is occupied, then utilizes
Back off algorithm, such as: binary exponential backoff algorithm until back off time arrives, then carries out channel monitoring, repeats the above process,
Until channel idle, start to send the information to be transmitted.
And in this process, the solution after broadcast frame collides and loses is not provided.The hair of broadcast frame
Passing through journey does not have the handshake mechanism of RTS/CTS, when transmitting broadcast frame, it may occur that following several situations: first is that hiding
The problem of terminal, a node can receive the broadcast frame sended over from other nodes simultaneously, lead to the conflict of broadcast frame;Two
It is under multi-channel model, a node gives its neighbor node to send broadcast frame, and its neighbor node on a control channel
Data frame may be sent on a data channel, since transceiver channel is not on a frequency point, will lead to the loss of broadcast frame.
These above-mentioned situations can occur under CSMA/CA mechanism, but the mechanism does not provide solution to the problem.Cause
This proposes the broadcast channel method for reliable transmission under CSMA/CA mechanism, maintenance cordless communication network that can be fast and reliable.Especially
Be in wireless Ad Hoc and Mesh network, due to network capacity becomes larger, within the scope of coverage neighbor node number increase, topology
Caused by structure change when broadcast frame loss, it can also make network fast convergence and the routing that timely updates.
Broadcast frame in the prior art, which is sent, uses CSMA/CA mechanism, in multi-channel case, 1) preset it is N number of
The channel not overlapped;2) each node keeps the monitoring to N number of channel;3) when node prepares one information frame of broadcast, inspection
Look into idle channel list;4) it monitors for empty channel, a length is waited to be at least the period of an interframe space, and
Check whether always below ST (sensed threshold of node) RSS (received signal strength) in this interframe space;5) random
Any moment point in backoff period is accessed, checks whether RSS is always below ST, that is to say, that the channel in random-backoff time
Want idle;6) by used channel labeled as " the last used channel ";7) if this last time used
Channel be the free time if, just selection sends information on this channel, if this channel busy, just random selection one is idle
Channel sends broadcast frame.As it can be seen that broadcast frame is sent with multi channel CSMA/CA mechanism, although broadcast frame loss can be reduced
Probability improves reliability, but this way only reduces the general of conflict there is no broadcast frame loss is thoroughly solved the problems, such as
Rate, and to broadcast frame loss the problem of, do not provide solution.
Summary of the invention
Goal of the invention: the object of the present invention is to provide a kind of CSMA/CA machines that can effectively solve the problem that broadcast frame loss problem
Broadcast channel method for reliable transmission under system.
Technical solution: the broadcast channel method for reliable transmission under CSMA/CA mechanism of the present invention, node receive neighbours
After the broadcast frame that node is sent, if not receiving neighbours section yet later by the period thresholding that the neighbor node sends broadcast frame
The new broadcast frame sent is put, then the broadcast frame new to the neighbor node request retransmission.
Further, after node receives the broadcast frame that neighbor node is sent, start timer, if having received the neighbor node
Then timer resets and starts timing next time to the new broadcast frame sent, if the timing of timer has reached the neighbor node
The period thresholding for sending broadcast frame does not receive new broadcast frame but yet, then the broadcast frame new to the neighbor node request retransmission.
Further, the period thresholding that the described neighbor node sends broadcast frame is calculated according to formula (1):
N=T+t+ Δ t (1)
In formula (1), N is period thresholding, and T is broadcast frame sending cycle, and t is the unidirectional air interface transmission of single-hop of the neighbor node
Time delay, Δ t are shake time delay.
Further, the shake time delay includes processing delay, channel handover delay and antenna transmitting-receiving handover delay.
Further, to the process of the new broadcast frame of the neighbor node request retransmission are as follows: node is sent to the neighbor node
Then BREQ frame waits the neighbor node to retransmit new broadcast frame, if having received new broadcast in preset latent period
Frame, then ending request retransmission processes;If the waiting time is more than that preset latent period does not receive new broadcast frame yet, determine
The neighbor node and this node change neighbor information table not in the same network, delete the neighbor node, and to other neighbours
Node broadcasts information.
Further, if node needs to send data to the neighbor node, BREQ frame is existed together with data information
The neighbor node is sent on data channel.
Further, the BREQ frame includes subframe type field, source node id field and destination node id field.
The utility model has the advantages that effectively being solved the invention discloses the broadcast channel method for reliable transmission under a kind of CSMA/CA mechanism
It the problem of broadcast frame loss, copes in the case that network capacity becomes larger, neighbor node increases within the scope of coverage,
Frame loss is broadcasted to network fast convergence and routing update work bring pressure, especially in multichannel ad hoc network and Mesh net
Effect is more prominent in network.
Detailed description of the invention
Fig. 1 is the topology diagram of the ad hoc network of the specific embodiment of the invention;
Fig. 2 is that the broadcast frame of the specific embodiment of the invention is sent, broadcast frame frame losing detection and broadcast frame retransmit and negotiate
Process schematic;
Fig. 3 is the flow chart that the broadcast frame of the specific embodiment of the invention is sent;
Fig. 4 is the method flow diagram of the specific embodiment of the invention.
Specific embodiment
With reference to the accompanying drawings and detailed description, technical solution of the present invention is further introduced.
Present embodiment discloses the broadcast channel method for reliable transmission under a kind of CSMA/CA mechanism, and node receives
After the broadcast frame that neighbor node is sent, start timer, the timing if the new broadcast frame for having received neighbor node transmission
Think highly of and set and start timing next time, if the timing of timer has reached the neighbor node and sent the period thresholding of broadcast frame but
New broadcast frame is not received yet, then the broadcast frame new to the neighbor node request retransmission.
The period thresholding that the neighbor node sends broadcast frame is calculated according to formula (1):
N=T+t+ Δ t (1)
In formula (1), N is period thresholding, and T is broadcast frame sending cycle, and t is the unidirectional air interface transmission of single-hop of the neighbor node
Time delay, Δ t are shake time delay.Shake time delay includes processing delay, channel handover delay and antenna transmitting-receiving handover delay.
The process of the broadcast frame new to the neighbor node request retransmission are as follows: node sends BREQ frame to the neighbor node, so
It waits the neighbor node to retransmit new broadcast frame afterwards, if having received new broadcast frame in preset latent period, terminates
Request retransmission processes;If the waiting time is more than that preset latent period does not receive new broadcast frame yet, determine that the neighbours save
Point not in the same network, changes neighbor information table with this node, deletes the neighbor node, and broadcast to other neighbor nodes
Information.BREQ frame includes subframe type field, source node id field and destination node id field.If that lose is multiple neighbours
The broadcast frame of node, the destination node id field in that BREQ frame are just substituted with multicast address.If node request retransmission when
Time needs to send data to the neighbor node, BREQ frame can also be sent to this together with data information on a data channel
Neighbor node.The length of latent period can be the sum of the length of multiple broadcast cycles.
The selection that BREQ frame sends channel can defer to following principle: for the BREQ frame of unicast, select in idle number
It is believed that being sent on road Fd;If there are the contacts of data service for the neighbor node of node and reception BREQ frame, can be in the two
BREQ frame and data information are sent on the Fd channel of foundation simultaneously;If being lost the broadcast frame of multiple neighbor nodes, controlling
Multicast sends BREQ frame on channel Fc processed.
Neighbor node sends broadcast frame and refers to that neighbor node sends the selection broadcast of starting point random algorithm by frame after the power-up
Frame sends start time, and sends the process of broadcast frame periodically on control channel Fc with fixed cycle T.Frame sends starting point
Random algorithm refers in a defined time window one value of random selection, then by this time value and node ID number into
The start time point of broadcast frame is initiated in row logical operation after being powered on.
Control channel Fc refers to the dedicated channel to send broadcast frame and negotiation information.The channel is established rules really, can be
Node power on after select default configuration channel, be also possible to after node powers on through by channel negotiation come out.This control letter
Road Fc can carry out dynamic negotiation according to channel quality, but the whole network shares a control channel, and broadcast frame is being controlled
It is sent on channel processed.
Node in present embodiment is the abbreviation of " apparatus for network node ", in the wireless signal coverage area of node
Other nodes that can be communicated with each other are known as the adjacent node of this node, and node can be terminal device, trunking or base station
Equipment.Cordless communication network is a non-stop layer, distributed mobile network, its in the node and the same network in network
He can communicate with each other node, support the increase of arbitrary node and exit.Multichannel CSMA/CA mechanism, refers to interactive letter
The transmission process of breath follows CSMA/CA, that is to say, that first to investigate the busy of channel at first, wait until channel idle
When, send message;If channel be it is busy, select back off time, listen to channel, until channel idle is got off, there is transmission
The qualification of message.
Technical solution of the present invention is further introduced with one embodiment below.
Cordless communication network in the present embodiment is as shown in Figure 1, there are multiple nodes in network, and there are two each node tools
Channel, a channel is for receiving signal;Another channel both can be used for sending signal, can be used for receiving signal, but
It is that transmitting-receiving cannot carry out simultaneously.
Below using node B as the sending node of broadcast frame, receiving node of the node A as broadcast frame, node C is as section
It is described in detail for the receiving node of point A transmission data.
As shown in Fig. 2, after node A receives the broadcast frame that node B is sent, parsing broadcast frame obtain B node ID number and
The information such as broadcast frame sending cycle T.Then node B is calculated according to formula (1) and sends the period thresholding N of broadcast frame, and started
Timer starts timing.When node B sends next frame broadcast frame to node A, node A sends data frame to node C,
Since node A can not receive information when sending information, so the next frame broadcast frame that node B is sent to node A just connects
It can not receive.When node A reaches period thresholding N for the timer of node B, node A sends BREQ frame to node B, waits section
Point B retransmits next frame broadcast frame, if having received next frame broadcast frame in preset latent period, ending request was retransmitted
Journey;If the waiting time is more than that preset latent period does not receive next frame broadcast frame yet, predicate node B and this node do not exist
In the same network, neighbor information table is changed, deletion of node B, and to other neighbor node broadcast messages.If Node A requests
It needs to send data to node B when re-transmission, BREQ frame can also be sent jointly to node B together with data information.
Fig. 3 is the process that node B sends broadcast frame, after node B is powered on, starting point random algorithm is sent using frame, for section
Point B selects the initiation time point of broadcast frame, as gap periods sends broadcast frame using broadcast cycle T.Wherein, frame sends starting point
Random algorithm is one value t of random selection in a defined time window W, then by this time value t and node ID number into
The start time point of broadcast frame is initiated in row logical operation after being powered on.
Below using node B, C, D, E, F, G as the sending node of broadcast frame, node A is as the receiving node of broadcast frame
Example is described in detail.
As shown in figure 4, parsing these broadcast after node A receives the broadcast frame that neighbor node B, C, D, E, F, G are sent
Frame, obtains the ID number of each neighbor node, and node A is recorded in the information table of respective neighbor node according to the ID number of neighbor node
Under at the time of receive broadcast frame, each neighbor node is then calculated according to formula (1) and sends the period thresholding N of broadcast frame, and is opened
Each timer is moved, timing is started.If each timer is not up to period thresholding N, node A has just had been received by each neighbours
The broadcast frame of node, then without starting retransmission mechanism.If the timer for node E has reached period thresholding N, and node A
The next frame broadcast frame that node E is sent is not received yet, then node A sends BREQ frame to node E, and node E is waited to retransmit next frame
Broadcast frame, if having received next frame broadcast frame in preset latent period, ending request retransmission processes;If waited
Between be more than that preset latent period does not receive next frame broadcast frame yet, then predicate node E and this node not in the same network,
Change neighbor information table, deletion of node E, and to other neighbor node broadcast messages.If being directed to the timer of node B, C and D
Respective period thresholding N is had reached, and node A does not receive the next frame broadcast frame that node B, C and D are sent yet, then node A exists
To node B, C and D multicast BREQ frame in control channel, node B, C and D is waited to retransmit next frame broadcast frame, if preset
Next frame broadcast frame is had received in latent period, then ending request retransmission processes;If the waiting time is more than preset waiting week
Phase does not receive the next frame broadcast frame of one or more nodes yet, then determines respective nodes and this node not in the same network
In, neighbor information table is changed, deletes respective nodes, and to other neighbor node broadcast messages.
Claims (5)
1. the broadcast channel method for reliable transmission under a kind of CSMA/CA mechanism, it is characterised in that: node receives neighbor node transmission
Broadcast frame after, if by the neighbor node send broadcast frame period thresholding after do not receive yet the neighbor node transmission
New broadcast frame, the then broadcast frame new to the neighbor node request retransmission;
The process of the broadcast frame new to the neighbor node request retransmission are as follows: node sends BREQ frame to the neighbor node, then etc.
New broadcast frame is retransmitted to the neighbor node, if having received new broadcast frame, ending request in preset latent period
Retransmission processes;If the waiting time be more than preset latent period do not receive new broadcast frame yet, determine the neighbor node with
This node changes neighbor information table not in the same network, deletes the neighbor node, and broadcast and believe to other neighbor nodes
Breath;
Following principle is deferred in the selection that BREQ frame sends channel: for the BREQ frame of unicast, being selected in idle data channel Fd
Upper transmission;If there are the contacts of data service for the neighbor node of node and reception BREQ frame, in the Fd channel that the two is established
Above while sending BREQ frame and data information;If being lost the broadcast frame of multiple neighbor nodes, the group on control channel Fc
It broadcasts and send BREQ frame.
2. the broadcast channel method for reliable transmission under CSMA/CA mechanism according to claim 1, it is characterised in that: node
After the broadcast frame for receiving neighbor node transmission, start timer, if the new broadcast frame for having received neighbor node transmission
Timer resets and starts timing next time, if the timing of timer has reached all Qimens that the neighbor node sends broadcast frame
Limit does not receive new broadcast frame but yet, then the broadcast frame new to the neighbor node request retransmission.
3. the broadcast channel method for reliable transmission under CSMA/CA mechanism according to claim 1, it is characterised in that: described
The period thresholding that the neighbor node sends broadcast frame is calculated according to formula (1):
N=T+t+ Δ t (1)
In formula (1), N is period thresholding, and T is broadcast frame sending cycle, when t is the single-hop unidirectional air interface transmission of the neighbor node
Prolong, Δ t is shake time delay.
4. the broadcast channel method for reliable transmission under CSMA/CA mechanism according to claim 3, it is characterised in that: described
Shake time delay includes processing delay, channel handover delay and antenna transmitting-receiving handover delay.
5. the broadcast channel method for reliable transmission under CSMA/CA mechanism according to claim 1, it is characterised in that: described
BREQ frame includes subframe type field, source node id field and destination node id field.
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