CN102264101B - Data transmission method used for underwater acoustic sensor network system - Google Patents

Abstract

The invention provides a data transmission method used for an underwater acoustic sensor network system. The method comprises the following steps: (1) a sink node sends control information to a lower level node; (2) each sensor node sends or forwards the control information; (3) each sensor node uploads and forwards data acquired or received by the node itself to an upper level node, wherein when uploading the data, a receiving terminal (an upper level node) returns an acknowledgement frame for each received data frame, a sending terminal (a lower level node) sets a sending window with a length of Ntw, and when not receiving an acknowledgement frame corresponding to a data frame, the sending terminal continuously sends Ntw data frames at most begin with the data frame. According to the invention, a sparse distribution mode requirement is satisfied; each node has a reliable data uploading link; carrying out accurate synchronization and timing are not needed; the method in the invention is suitable for an irregular network shape. According to the invention, in an underwater acoustic channel of a harsh condition, both integrality of data uploading and network transmission efficiency are guaranteed, and data transmission efficiency is effectively raised.

Description

A kind of data transmission method for underwater sound sensor network system

Technical field

The present invention relates to sensor network technique field, specifically, the present invention relates to a kind of data transmission method for underwater sound sensor network system.

Background technology

Tradition land forms by being deployed in a large amount of cheap microsensor nodes in surveyed area with wireless sensor network, the self-organizing system with certain topological structure forming by communication, it have self-organization, dynamic, data-centered, with the feature such as application is closely related.Node in wireless sensor network can adopt various types of transducers (as sound, optical, electrical, heat sensor etc.), with regard to access media, tradition land with wireless sensor network mostly taking atmosphere as access media, and generally adopt electromagnetic wave as transmission data carrier.With regard to topological structure, wireless sensor network mainly contains Star Network, point to point network, self-organizing network and Cluster Networks at present.Above-mentioned existing various topological structures be all difficult to adapt to submerged applications environment.Its reason is as follows:

1, water sound sensor network node cost is higher, and each node will be responsible for large as far as possible area of detection, therefore mostly takes the sparse mode that lays.Lay in mode sparse, in water sound sensor network, each node can only be communicated by letter with the adjacent node of minority.And the topological structures such as Star Network of the prior art, point to point network, self-organizing network all require any two nodes in network all can communicate, therefore they all do not meet the sparse requirement that lays mode.

2, owing to taking the sparse mode that lays, the correlation between the each node data in water sound sensor network is very little, almost there is no redundant data, therefore needs to ensure that each node has reliable data upload link.In existing Cluster Networks, the node in certain limit can spontaneously be elected a leader cluster node, and is responsible for the correspondence with foreign country of this bunch by bunch head.But, sparse while laying mode when adopting, can not ensure that each elected leader cluster node has reliable data upload link, therefore Cluster Networks does not meet the sparse requirement that lays mode yet.

3, in the wireless sensor network of land, signal is with light velocity propagation in air, and transmit after receive time delay is very little, generally can ignore.Can only utilize under water acoustical signal to carry out the transmission of information, between its network node, propagation delay time is larger, is therefore difficult to realize accurate synchronous and timing.

4, under water in acoustic sensor network, due to factor of natural environment, the position of sensor node can be subject to larger disturbance, therefore be difficult to form stable regular network shape (as square, triangular net etc.), this just has higher requirement to self organization ability to underwater sensor network.

In sum, current wireless sensor network and data transmission method thereof cannot be applicable to submerged applications environment, need a kind of brand-new underwater sound sensor network system that can be applicable to submerged applications environment.And that underwater sound sensor network system has the propagation delay time of signal is long, data integrity requires high, transmission bandwidth is less, the limited energy of sensor node and the specific question such as be difficult to supplement, existing data transfer mode is difficult to reach requirement and cannot be suitable for even at all, therefore current in the urgent need to a kind of data transmission method matching with underwater sound sensor network system is provided.

Summary of the invention

The object of this invention is to provide a kind of data transmission method for underwater sound sensor network system.

For achieving the above object, the invention provides a kind of data transmission method for underwater sound sensor network system, described underwater sound sensor network system comprises aggregation node and sensor node, wherein, aggregation node is the 0th node layer, and distance between the aggregation node sensor node within the scope of efficient communication is the 1st node layer; For each i node layer, remove upper layer node and with outside node layer, the sensor node with the distance of this i node layer within the scope of efficient communication is i+1 node layer, and wherein i is positive integer, and i node layer is the upper layer node of i+1 node layer;

Described data transmission method comprises:

1) aggregation node sends control information to lower level node;

2) each sensor node sends or forwards control information to lower floor;

3) each sensor node uploads to upper layer node the data that this node gathers, and forwards the received data of being uploaded by lower level node of this node to upper layer node; In the time of uploading data, receiving terminal (being upper layer node) returns to an acknowledgement frame for its each received Frame, and it is N that transmitting terminal (being lower level node) arranges length _twsend window, transmitting terminal, in the time not receiving acknowledgement frame corresponding to a certain Frame, sends taking this Frame as initial N at most more continuously _twindividual Frame.

Wherein, described step 3) in, for each transmitting terminal, send window is set respectively, the length of transmitting terminal window

$N_{\mathrm{tw}}=\frac{{2D}_{\mathrm{est}}+V_s{T}_g}{V_s(t_p+t_g)}$

Wherein, D _estit is the distance between sending node and receiving node; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _gbe for fear of due to estimation inaccurate guard time interval of introducing; t _pto send the frame data time used; t _git is the interval time in the middle of transmission two frame data.

Wherein, described step 3) in, transmitting terminal retransmits timer and carries out countdown sending all to start when each Frame, retransmits corresponding data frame while meeting following two kinds of conditions are any: 1. transmitting terminal is not received the acknowledgement frame of certain sequence number X Frame and the re-transmission timer value of this frame is kept to 0; 2. transmitting terminal receives the acknowledgement frame of other frames of jump sequence number, and in this acknowledgement frame, has carried the retransmission information of the frame that sequence number is X.

Wherein, described step 3) in, the number of times upper limit of re-transmission is set as 5 times, for a certain Frame, when retransmitting while also not receiving corresponding acknowledgement frame after 5 times, judges that communication link is cut off.

Wherein, described step 3) in, the initial value of described re-transmission timer calculates with following formula:

$T_{\mathrm{left}}=\frac{{2D}_{\mathrm{est}}+V_s{T}_g}{V_s}$

Wherein, T _leftthe initial value that retransmits timer, D _estit is the distance between sending node and receiving node; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _gbe for fear of due to estimation inaccurate guard time interval of introducing.

Wherein, described step 3) in, the distance B between sending node and receiving node _estintensity by sensor node received signal calculates.

Wherein, control information is carried out to redundant transmission.

Wherein, classifying importance is carried out in described control information, and the number of times of the higher control information redundant retransmission of importance is more.

Wherein, the Transmission Time Interval of the control frame of two redundant transmission is determined according to the average distance of network intermediate node and the control frame frame length that will transmit.

Wherein, in the time that a node can be communicated by letter with multiple upper layer node simultaneously, one of them upper layer node is defined as to father node, lower level node is preferentially by its father node uploading data.

Wherein, described step 3) adopt receiving terminal control crash mode to carry out data upload, comprise following sub-step:

31) determine the lower level node that needs uploading data;

32) upper layer node is sent COMPETE frame;

33) described lower level node is intercepted channel, and in the time receiving the COMPETE frame that its father node sends, transmission RTS frame is to its father node with contention channel, and request sends data;

34) upper layer node is sent CTS frame to the highest lower level node of priority;

35) described lower level node is receiving that, after the CTS frame that its father node sends, this lower level node is to its father node uploading data.

Wherein, under receiving terminal control crash mode, described step 3) also comprise following sub-step:

36) in the time that described lower level node is received the STOP frame that its father node sends, stop uploading data, get back to step 33).

Wherein, under receiving terminal control crash mode, described step 33) in, in the time of control frame except STOP frame that lower level node receives that priority sends higher than the node of its father node, the channel of this its uploading data of lower level node is set to busy state.

Wherein, described step 3) adopt transmitting terminal control crash mode to carry out data upload, comprise following sub-step:

31) determine the lower level node that needs uploading data;

32) described lower level node is intercepted channel, and in the time that the NAV of the frame not transmitting in channel and this lower level node value is 0, this lower level node sends RTS frame and carries out channel contention to father node, and request sends data;

33) upper layer node is sent CTS frame to the highest lower level node of priority;

34) described lower level node is receiving that, after the CTS frame that its father node sends, this lower level node is to its father node uploading data;

Described NAV value real-time update,

${\mathrm{NAV}}_{\mathrm{left}}=\min ({\mathrm{NAV}}_{\mathrm{rcv}}-\frac{D_{\mathrm{rcv}}+D_{\mathrm{des}}}{V_s}+T_g)$

Wherein, NAV _leftbe the NAV value in node this locality of monitor channel just, this value is to represent that node can send RTS contention channel at 0 o'clock; NAV _rcvit is NAV " field " value in DATA or the ACK frame receiving; D _rcvbe this node of estimating of the amplitude of the signal received by receiver and send the distance between signal node; D _desto receive the distance between this node that the amplitude of signal estimates and the node that will communicate by receipts machine; V _sthe speed of acoustical signal under the Underwater Acoustic Environment of network place; T _git is the guard time interval of introducing in order to prevent from calculating mistake.

Wherein, under transmitting terminal control crash mode, described step 3) also comprise following sub-step:

35) in the time that described lower level node is received the STOP frame that its father node sends, stop uploading data, get back to step 32).

Wherein, under transmitting terminal control crash mode, described step 32) in, in the time of control frame except STOP frame that lower level node receives that priority sends higher than the node of its father node, the channel of this its uploading data of lower level node is set to busy state.

Wherein, the frequency band that described underwater sound sensor network system uses comprises first, second, third data message frequency band; If certain node level is N, meet N mod 3=0, this node is 1 category node (mod is for getting remainder operation), meet N mod 3=1, this node is 2 category nodes, meet N mod3=2 this node be 3 category nodes, communicating by letter between 1 category node and 2 category nodes, 2 category nodes and 3 category nodes, 3 category nodes and 1 category node adopts respectively first, second, third data message frequency band.

Wherein, the frequency band that described underwater sound sensor network system uses also comprises control information arrowband, and the control information between each node is used control information arrowband to transmit.

Wherein, in the time that a node can be communicated by letter with multiple upper layer node simultaneously, one of them upper layer node is defined as to father node, and determines that other upper layer node is pseudo-father node, this node is preferentially by its father node uploading data.

Wherein, in the time that a node can communicate with multiple lower level nodes simultaneously, judge the priority of the father node of each lower level node, when the father node of lower level node described in the priority ratio of oneself high, and when the father node of this lower level node is same node layer, determine that this lower level node is the child node of oneself; When the father node of lower level node described in the priority ratio of oneself is low, and the father node of this lower level node is while being same node layer, determines that this lower level node is the pseudo-child node of oneself.

Wherein, each sensor node is all preserved the local topology information of this sensor node in this locality, described local topology information comprises: father node numbering, pseudo-father node numbering and quantity, child node numbering and quantity, pseudo-child node numbering and quantity, and same node layer numbering and quantity in communication range.

Wherein, described aggregation node number is greater than 1, a region of the sensor network system of each aggregation node control; The local topology information that described sensor node is preserved in this locality comprises: pseudo-father node numbering in region, pseudo-child node numbering in region, interregional pseudo-father node numbering, and interregional pseudo-child node numbering and quantity.

Compared with prior art, the present invention has following technique effect:

1, in the present invention, each node only need to be communicated by letter with a small amount of adjacent node, meets the sparse requirement that lays mode;

2, in the present invention, each node has reliable data upload link;

3, the present invention does not need to carry out accurate synchronous and timing;

4, the present invention does not have particular/special requirement to network shape, applicable to various irregular network shapes;

5, the present invention can farthest control data collision, ensures the integrality of data upload under band-limited objective condition;

6, the efficiency of energy utilization of sensor node of the present invention is high, can save the energy, improves useful life;

7, when the transmission conditions of underwater acoustic channel are better, the present invention can adopt transmitting terminal control crash mode and control information arrowband is set, can reduce so mutual (particularly having reduced the stand-by period of COMPETE frame) of control frame, significantly improve data upload efficiency;

8,, when the transmission conditions of underwater acoustic channel are poor, the present invention can adopt receiving terminal control crash mode to ensure data upload efficiency;

9, the present invention can also ensure the integrality of data upload and take into account the efficiency of Internet Transmission in the comparatively severe underwater acoustic channel of condition, has effectively improved data transmission efficiency.

Brief description of the drawings

Fig. 1 is the hiberarchy topology sensor network schematic diagram in one embodiment of the invention;

Fig. 2 is that the multipath in one embodiment of the invention forwards schematic diagram;

Fig. 3 is one embodiment of the invention medium priority rule schematic diagram;

Fig. 4 is TOPO_INIT frame structure schematic diagram in one embodiment of the invention;

Fig. 5 is TOPO_ACK frame structure schematic diagram in one embodiment of the invention;

Fig. 6 is the state transitions schematic diagram that in one embodiment of the invention, node sends data;

Fig. 7 is READY frame structure schematic diagram in one embodiment of the invention;

Fig. 8 is COMPETE frame structure schematic diagram in one embodiment of the invention;

Fig. 9 is CTS frame structure schematic diagram in one embodiment of the invention;

Figure 10 is STOP frame structure schematic diagram in one embodiment of the invention;

Figure 11 is ACK frame structure schematic diagram in one embodiment of the invention;

Figure 12 is RTS frame structure schematic diagram in one embodiment of the invention;

Figure 13 is DATA frame structure schematic diagram in one embodiment of the invention;

Figure 14 is FINISH frame structure schematic diagram in one embodiment of the invention;

Figure 15 is the state transitions schematic diagram that in one embodiment of the invention, node receives data;

Figure 16 is the work period schematic diagram of the sensor network in one embodiment of the invention;

Figure 17 is data direction of transfer schematic diagram in one embodiment of the invention;

Figure 18 is the flow chart (adopting receiving terminal control crash mode) that in one embodiment of the invention, data transfer phase child node sends data to father node;

Figure 19 is the flow chart (adopting transmitting terminal control crash mode) that in one embodiment of the invention, data transfer phase child node sends data to father node;

Figure 20 is the flow chart that in one embodiment of the invention, data transfer phase father node receives son node number certificate (adopting receiving terminal control crash mode);

Figure 21 is the flow chart that in one embodiment of the invention, data transfer phase father node receives son node number certificate (adopting transmitting terminal control crash mode);

Figure 22 is a kind of information frame frequency band division scheme schematic diagram in one embodiment of the invention; In this scheme, whole frequency band is divided into data message frequency band and control information arrowband;

Figure 23 is the schematic diagram that contains multiple aggregation node networks in one embodiment of the invention;

Figure 24 is another kind of information frame frequency band division scheme schematic diagram in one embodiment of the invention; In this scheme, do not contain special control information arrowband;

Figure 25 is the handling process schematic diagram of topological initial phase node in one embodiment of the invention;

Figure 26 is the information frame band allocation scheme schematic diagram in one embodiment of the invention;

Figure 27 is the performance comparison schematic diagram of receiving terminal control crash mode and transmitting terminal control crash mode in one embodiment of the invention;

Figure 28 is the significance level of each information frame and the schematic diagram of number of retransmissions in one embodiment of the invention;

Figure 29 is the first situation of level problem in region in one embodiment of the invention, the schematic diagram of the processing mode of topological initialization information between same level node;

Figure 30 is the second situation of level problem in region in one embodiment of the invention, the schematic diagram of the initialization issue handling mode causing under some node damaged condition;

Figure 31 is the third situation of level problem in region in one embodiment of the invention, the schematic diagram of the processing mode of the initialization problem causing under a kind of specific condition;

Figure 32 is the schematic diagram of interregional fringe node in one embodiment of the invention;

Figure 33 is that in one embodiment of the invention, two Area Node edge nodes carry out topological initialized schematic diagram;

Figure 34 is the processing mode schematic diagram in the time producing disturbed condition in transmitting procedure in one embodiment of the invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is further described.

According to one embodiment of present invention, a kind of underwater sound sensor network system is provided, this underwater sound sensor network system is the data acquisition network under water that node hierarchical lays, and it comprises aggregation node and general sensor nodes (hereafter sensor node).

Wherein, aggregation node is to have stronger disposal ability, the node that the data that common sensor node can be sent merge and (as wired, radio frequency etc.) sends higher level recruiting unit (as water surface ship etc.) in a certain way, is generally made up of wired or wireless transmitter module, underwater acoustic communication module, information processing and memory module, energy supply module etc.

Sensor node is the node that underwater information to be detected (as temperature, the salinity degree of depth etc.) can be converted to digital signal and be passed to upper layer node or aggregation node by underwater acoustic channel, and sensor node can be made up of sensor assembly, processor module, underwater acoustic communication module and energy supply module.

As shown in Figure 1, the underwater sound sensor network system of the present embodiment is disposed each sensor node formation and is besieged it ring upon ring type network centered by aggregation node.For making drawing clear, in Fig. 1, only carry out representational level relation with concentric circles simply, in fact, the level of each node is judged by following method: aggregation node is the 0th node layer, and the sensor node with the distance of aggregation node in underwater sound communication critical distance is the 1st node layer; For each i node layer, remove upper layer node and with outside node layer, the sensor node with the distance of this i node layer in underwater sound communication critical distance is i+1 node layer, wherein i is positive integer, i.e. i=1,2,3......, upper layer node is the node that level number is less.Should be appreciated that at node and lay position comparatively accurately time, the hierarchical relationship that above-mentioned decision rule forms is identical with the concentric round hierarchical relationship shown in Fig. 1.

Because the node cost of underwateracoustic network is very high, thus can only sparsely lay, in the hope of there being maximum area coverage.Therefore, the present embodiment criteria for classifying is between layers: adjacent level can direct communication, and non-adjacent level (not comprising with layer) cannot direct communication.Can realize above-mentioned criterion by distance and node power between control node.Such as, can first set the power threshold of each node, for arbitrary node, receiving after underwater sound signal, as its power lower than as described in power threshold, abandon this underwater sound signal.Because underwater sound signal is along with the increase of distance decays, therefore all can self-assembling formation underwater sound communication critical distance between every two nodes in sensor network, in the time that two internodal distances are less than or equal to underwater sound communication critical distance, these two nodes can direct communication, the two is adjacent node, in the time that two internodal distances are greater than underwater sound communication critical distance, these two nodes can not direct communication, and the two is non-conterminous node.In the present embodiment, distant between node (general at a distance of more than km), belong to sparse network, the data dependence that different nodes gather is less, data do not have redundancy, be that each node needs to send data to aggregation node, and the data volume that each node need to transmit is larger.Meanwhile, there is the problem of energy supply deficiency in sensor node, thus should reduce the communication disruption that signal collision causes as far as possible, to save the energy.

The underwater sound sensor network system of the present embodiment adopts sudden continuously-running duty.Node most of time is in resting state.In the time starting working, first aggregation node sends instruction to the whole network, all nodes are waken up, and start sensor is collected data (as temperature, salinity, the degree of depth etc.).Each node will pass to aggregation node by data collected this node.When the data of all nodes in network all complete after transmission, all nodes enter resting state.

Divide 7 parts to introduce in detail the various aspects of the underwater sound sensor network system of the present embodiment below.These 6 parts are respectively: definite method, Whole Work Flow, topology initializing method, data transmission method and the discussion about specific question of topological structure, media access control (MAC) method, pass-through mode and forwarding priority.

One, topological structure

The present embodiment has adopted topological structure by different level.As shown in Figure 1, the Hierarchical network of the present embodiment comprises 2 kinds of nodes: aggregation node and common sensor node.Whole network can be disposed multiple aggregation nodes according to actual conditions, and each aggregation node solidifies different area information to each sensor node is incorporated in correct region in the time that topology generates.The present embodiment can also be centered by each aggregation node, forms multiple small-scale Hierarchical networks, as shown in figure 23.Within fringe node can belong to specific network range according to the priority principle of the child node in the present embodiment, father node (this part will be described below).

In the present embodiment, regulation aggregation node is the 0th layer, and adjacent lower one deck can communication node be the 1st layer with it, and lower one deck adjacent with the 2nd layer can communication node be the 2nd layer, the like.As shown in Figure 1, the standard of separating is between layers as follows:

Utilize the distance of communication as drawing with different levels standard, the tolerance of communication distance is exactly the intensity of receiver signal.Suppose that the model of each node transmitter is identical and energy supply is sufficient, thereby the underwater sound signal intensity that each node sends is substantially identical, is made as A.At receiving terminal, signal is decay to some extent after underwater acoustic channel transmission, the function that the size of decay is distance.Signal strength signal intensity at receiving terminal can be expressed as:

A _r＝A _t×A _l

Wherein, A _rbe the amplitude that receiving node is received, A is the signal amplitude that transmitting node sends, A _lrepresent the reduction ratio of the amplitude in communication process, this coefficient is the function of two euclidean distance between node pair.

In topological forming process, work as A _ramplitude while being less than certain predefined threshold value, receiving node will not do any processing to this signal, this has just ensured in topological structure that the node communication between adjacent two layers is all within the reliable scope in ensureing.

Two, media access control (MAC) method

The present embodiment adopts the media access way based on competition, allows node contention channel as required.The mechanism of contention channel adopts RTS, the CTS handshake method of similar MACA, but has carried out corresponding improvement according to the feature of underwater acoustic channel.

(1), in the present embodiment, communication between layers adopts layering frequency division mechanism.The frequency band that between each layer, communication (mainly referring to data upload) is used is divided into three sections, is respectively first, second, third data message frequency band, and physical planning as shown in figure 26.

Wherein the level of 1 category node meets (establishing node level is N, and mod is for getting remainder operation)

N mod 3＝0；

The level of 2 category nodes meets

N mod 3＝1

The level of 3 category nodes meets

N mod 3＝2

Communicating by letter between 1 category node and 2 category nodes, 2 category nodes and 3 category nodes, 3 category nodes and 1 category node adopts respectively first, second, third data message frequency band.

In the present embodiment, for the frequency of occurrences the highest 3 kinds of frame: RTS, CTS, ACK, can mark off separately arrowband by rule and transmit, this arrowband is called control information arrowband, and its dividing mode as shown in figure 22.

What deserves to be explained is, the control information arrowband in the present embodiment can be cancelled, and now RTS, CTS, ACK frame can directly use corresponding data message frequency band to transmit.Do not adopt control information narrow band transmission layering frequency division mechanism frequency division method as shown in figure 24, band plan is as shown in figure 26.

In the time that band resource is not bery nervous, control information arrowband can be set, can make so same node layer not interfere with each other in the time receiving, can work with node layer under many circumstances simultaneously.

In the time that band resource is nervous, control information arrowband can be set.Now, the data message that control information and the lower level node sending to lower floor due to same node layer sent, in same frequency range, can disturb, so cannot work with the node in mutual communication range of layer simultaneously.

The media access control scheme of the present embodiment can adopt transmitting terminal control collision scheme, also can adopt receiving terminal control collision scheme (particular content will be explained in greater detail below, the two performance comparison can referring to Figure 27).In the time adopting transmitting terminal control collision, control information arrowband must be set.

(2) the present embodiment adopts Sr-ARQ (AutomaticRepeat-reQuest) mechanism according to the feature of network, and in this mechanism, data receiver sends after data not can be at once by this data destroying, but deposits a buffer memory in.When all frames of receiving as recipient are all correct, judgement receives successfully, now just buffer memory is emptied; In the time that receiving terminal detects that certain frame occurs mistake or lost some frame, the sequence number of erroneous frame or lost frames is sent to data receiver, transmit leg is retransmitted these Frame.Accordingly, transmit leg, in the case of the confirmation or the jump of confirmation sequence number of not receiving recipient, will retransmit these information frames that are not identified.

(3) the present embodiment also needs to arrange send window.

Send window is exactly that transmitting terminal is in the data information frame number that does not obtain allowing the in the situation that receiving terminal being confirmed transmission.For making full use of channel, this agreement adopts following formula to calculate the size of transmitting terminal window.

$N_{\mathrm{tw}}=\frac{{2D}_{\mathrm{est}}+V_s{T}_g}{V_s(t_p+t_g)}$

Wherein N _twit is send window size; D _estthe distance between sending node and receiving node, can be by the strength estimation of reception signal out; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _gbe for fear of due to estimation inaccurate guard time interval of introducing, assignment as the case may be; t _pto send the frame data time used; t _gthe interval time in the middle of transmission two frame data, assignment as the case may be.

(4) the present embodiment has the overtime retransmission mechanism of transmit leg.Transmit leg all starts re-transmission timer and carries out countdown in the time sending each Frame.Agreement is defined in retransmitting data frame when following two kinds of conditions are any to be met: 1, be kept to 0 not receiving the ACK of certain sequence number (X) Frame and the re-transmission timer value of this frame; 2, jump sequence number has been received the ACK of other frames, and in ACK, has carried the retransmission information (Figure 11 is shown in by the frame structure of ACK) of the frame that sequence number is X.The number of times of overtime re-transmission is in a preferred embodiment set as 5 times.Reply ACK if also do not received after exceeding 5 times, just think that communication link is cut off, by error logging and report to upper strata control program.The initial value of the re-transmission timer of the present embodiment calculates with following formula:

$T_{\mathrm{left}}=\frac{{2D}_{\mathrm{est}}+V_s{T}_g}{V_s}$

Wherein, T _leftthe initial value that retransmits timer, D _estthe distance between sending node and receiving node, can be by the strength estimation of reception signal out; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _gbe for fear of due to estimation inaccurate guard time interval of introducing, assignment as the case may be.

(5) the present embodiment carries out redundant transmission to control information.For guaranteeing correct transmission and the processing of important control information, take into account the reasonable utilization of Internet resources simultaneously, the present embodiment carries out classifying importance to different information frames, determines to repeat on this basis the number of times of transmission, and the specific implementation method adopting in the present embodiment can be referring to Figure 28.The time interval of the control frame of two redundant transmission is determined according to the average distance of network intermediate node and the control frame frame length that will transmit.Its minimum value and maximum are calculated according to following formula:

minT _sep＝2t _p

maxT _sep＝3t _p

Wherein, t _prepresent that single transmits the control frame time used of respective type.When concrete enforcement, produce minT _sepwith maxT _sepbetween random number, as the time interval of redundant transmission control frame.

Three, definite method of pass-through mode and forwarding priority

In the present embodiment, each node can only with the node communication of adjacent layer, if so want just must be via the forwarding of upper layer node to aggregation node by communication for lower level node, in the network course of work, N node layer is striven data information transfer to N-1 node layer.

As shown in Figure 2, due to the feature of clustering topology, in most of the cases each node can communicate with 2 or multiple upper layer node, for avoiding channel confliction and saving resource, is necessary to specify by certain priority rule the node of bearing forwarding task.

Briefly introduce the series of rules that the present embodiment carries out data retransmission below:

1, in network, each node has unique node serial number.

2, in same layer node, node serial number is less, and priority is larger.

3,, in the process of contention channel, the communication request that father node priority is larger will be allowed to use channel.

4, in the process of contention channel, to judge in own same node layer, whether have highlyer than own priority in preparing the node of accepting state, if had, postpone a period of time transmission COMPETE or CTS frame, to ensure the communication of priority node.Detailed content is the explanation of preparing accepting state about father node of middle data transmission method part vide infra.

5, in adjacent two layers node, the node that sends data and reception data is called the other side's child node and father node, and the data that child node is sent are responsible for forwarding by father node.

6, in the time that node can be communicated by letter with multiple upper layer node simultaneously, less node serial number that is called to father node, assert that other upper layer node is pseudo-father node, as shown in Figure 3 simultaneously.

If when 7 certain node are simultaneously adjacent with the node of two or more same regions different levels, what only assert node level minimum is father node, the shortest with guarantee information transmission path.

8,, in interregional transmitting procedure, interregional pseudo-child node has higher priority.

9, node is not processed the topological initialization information of sending with the node of oneself setting up topological hierarchical relationship, to avoid repetition initialization phenomenon (this situation occur due to network topology is unreasonable or node damage cause " spiral " initialization phenomenon).

10, in the time that a node can communicate with multiple lower level nodes simultaneously, judge the priority of the father node of lower level node by the transmission (this process completes at topological structure initial phase) of local topology information, when oneself priority ratio another when high with node layer (numbering less), think that this lower level node is child node; Otherwise think that it is pseudo-child node.

11,, in region in transmitting procedure, in region, the transmission of pseudo-child node has higher priority.

12, in transmitting procedure, if when appearance two sends information with node layer by same frequency range, what node serial number was less has higher priority.

13, the topological information generated that the affiliated area of interregional node is received by first is determined.

14,, in the time of transmission, child node only just can be sent channel contention request in the time judging the equal free time of channel of pseudo-child node in father node and all pseudo-father nodes, region.

15, certain two node, from setting up rational communication link, until communication process finishes to have the highest communication priority, can not be interrupted by other node.

16,, according to the data-centered feature of sensor network, this agreement will not focused on the fairness of each node contention to channel.

Four, Whole Work Flow

According to the present embodiment, for " node hierarchical lays network ", according to the Rulemaking procotol described in last point, the work of this agreement and the working method of network are closely related.

In procotol, the time cycle of each node work as shown in figure 16.As can be seen from Figure 16, the course of work of the sensor network of the present embodiment is mainly divided into topological initial phase and data transfer phase.Introduce respectively below:

1, topological initial phase

In this stage, the aggregation node in network sends wake-up signal, receives information relevant under the nodes records of this signal, returns to response message; The downward node layer of wake-up signal that simultaneously produces oneself sends, and receives response message.The rest may be inferred, until all nodes of the whole network are all waken up.In this wakeup process, the each node in network is set up with different levels network topology structure as shown in Figure 1 according to the topology information of carrying in the wake-up signal receiving.

2, data transfer phase

At data transfer phase, in network, the task of each node is that the information that information itself that oneself will will be transmitted and the lower floor receiving are transmitted up all reaches upper layer node.The information direction of transfer of whole network as shown in figure 17.It should be noted that, each node only sends father node to information, and for each child node, father node is unique.

At data transfer phase, a node is father node to its lower floor, is child node to its upper strata.Owing to having adopted layering frequency division, control information narrow band transmission mechanism, concerning some nodes, receive the information of lower level node and can regard two completely independently processes as to upper layer node transmission information.In addition, the present invention can adopt receiving terminal control crash mode and two kinds of mode of operations of transmitting terminal control crash mode.Wherein, Figure 18 shows certain node under data transfer phase receiving terminal control crash mode and uploads to its father node the process of information.Figure 19 shows certain node under data transfer phase transmitting terminal control crash mode and uploads to its father node the process of information.Figure 20 shows certain node under data transfer phase receiving terminal control crash mode and receives the process of the information of its child node.Figure 21 shows certain node under data transfer phase transmitting terminal control crash mode and receives the process of the information of its child node.The particular content of data transfer phase will be explained in greater detail below.

Five, topology initializing method

The node processing flow process of topology initial phase as shown in figure 24.In certain moment, aggregation node sends topology by wireless channel and generates (TOPO_INIT) frame, and its effect is after network design completes, to form adaptive network topology.TOPO_INIT frame format is as shown in table 1:

Table 1

Field name	Effect
		fun	Function field, is fixed as 0
layer	Instruction receives the node place number of plies of this information, and its value adds 1 for the sending node number of plies
		parent_id	The numbering of father node

Receiving node comprises following step to this frame processing:

1,, in the time that node receives first TOPO_INIT frame, take out the value of layer field as the number of plies information of oneself; Preserve the father node numbering of parent_id field value as oneself; The Field Number that the value of preserving region field is oneself.

If 2 values that receive the layer field of the TOPO_INIT frame that same Area Node sends are that this node place number of plies adds 1, judgement has received the information of issuing lower level node with node layer so.Now the value in parent_id field is stored in same node layer table.

3, generate new topological delta frame, send to lower level node by correct frequency channels.Fun field is composed 0, layer field and is composed the numbering that this node place number of plies adds 1, parent_id field and compose this node oneself, and region field is composed the numbering in territory, this node place.New topological delta frame is not to issue lower level node at once, but sends after the segment protect time of wait again, and object is to wait for that the topological delta frame that receives all upper layer node all sends after treatment again.

4, generation topology generates and replys bag (TOPO_ACK), and returns to upper layer node by correct frequency channels, information updating child node and the pseudo-child node list wherein of upper layer node basis.

If 5 receive the TOPO_INIT frame that the upper layer node of the higher priority (node serial number is less) that same Area Node sends is sent, so just father node is before identified as to pseudo-father node, the upper layer node newly receiving is identified as father node.And repeat the 4th step, upgrade the 3rd step.

6, receiving under the TOPO_INIT frame prerequisite of one or more same regions, if the TOPO_INIT frame layer field value of newly receiving be greater than the number of plies of this node and with territory, this node same district, illustrate and now run into the level problem in region.Now check child node list, if this node, in child node list, directly abandons this frame; If this node not in child node list, by parent_id field store in " pseudo-father node list in region ".

7, receiving under the TOPO_INIT frame prerequisite of one or more same regions, if the TOPO_INIT frame layer field value of newly receiving be less than the number of plies of this node and with territory, this node same district, illustrate and now run into the level problem in region.Check " pseudo-child node list in region ", if having this node in table, so directly abandon this frame; If do not have in table, original information in father node list is transferred in " pseudo-father node list in region ", the number of plies information updating of this node is layer field value, corresponding parent_id field is stored in father node list, and repeat the 4th step, upgrade the 3rd step.

8, in the time receiving the TOPO_INIT frame of zones of different, illustrate that this node belongs to " interregional node ", stop immediately sending TOPO_INIT frame to lower floor.Now the parent_id field of this frame is stored in " interregional pseudo-father node list ".

It is as shown in table 2 that topology generates reply frame (TOPO_ACK) form:

Table 2

Field name	Effect
		Fun	Function field, is fixed as 1
child_id	Child node numbering
		child_layer	Child node number of plies information
parent_id	Father node numbering
		region	Area information

Upper layer node will be taken out child_id field value after receiving this frame, and identify the child node that it is oneself.Likely there are following several situations:

(1) frame of receiving is that same region and parent_id field are the node numbers of oneself, identifies so it for child node, if this node serial number is present in other any node listings, deleted, and by the information storage of this node in child node list.

(2) frame of receiving is that same region and parent_id field are not the node numbers of oneself, check child_layer field value, point three kinds of situation discussion: the first, if this value equate with the network layer information of oneself, the person of sending of frame is stored in same node layer list.The second, if subtracting 1 with the network layer information of oneself, this value equates, the person of sending of frame is stored in " pseudo-child node list ".The 3rd, if this value and oneself network layer information do not subtract 1 not etc., illustrate level problem in region has occurred.Now this value is subtracted to 1 with the network layer information of oneself and compare, if the former is less, illustrate that lower level node has found the father node that priority is higher, this lower level node numbering is stored in special " pseudo-child node list in region "; If the former is larger, illustrate that this lower level node does not also receive the topological initialization information of oneself, or also do not give a response, continue to wait for.

(3) when the frame of receiving is zones of different, illustrate that this node belongs to " interregional node ", now the child_id field of this frame is stored in " interregional pseudo-child node list ".

Carry out after topological initialization according to above-mentioned steps, each node has recorded local topology information: father node numbering, pseudo-father node numbering and quantity, child node numbering and quantity, pseudo-child node numbering and quantity, same node layer numbering and quantity in communication range, pseudo-child node, interregional pseudo-father node, interregional pseudo-child node and quantity in pseudo-father node, region in region.

Six, data transmission method

At data transfer phase, a node is father node to lower floor, is child node to upper strata.Owing to having adopted layering frequency division, control information narrow band transmission mechanism, concerning some nodes, receive the information of lower level node and can regard two completely independently processes as to upper layer node transmission information.In addition, the present invention can adopt receiving terminal control crash mode and two kinds of mode of operations of transmitting terminal control crash mode (the two is MAC layer control collision mode).Wherein, Figure 18 shows certain node under data transfer phase receiving terminal control crash mode and uploads to its father node the process of information.Figure 19 shows certain node under data transfer phase transmitting terminal control crash mode and uploads to its father node the process of information.Figure 20 shows certain node under data transfer phase receiving terminal control crash mode and receives the process of the information of its child node.Figure 21 shows certain node under data transfer phase transmitting terminal control crash mode and receives the process of the information of its child node.Introduce respectively the scheme that child node sends data and father node reception data below.

6.1, child node sends data

At data transfer phase, the child node of sending data has three kinds of states: wait for transmission state, transmission state, completion status.Jump condition between each state as shown in Figure 6.Just analyze situation and the methods of disposal of this node under two kinds of control crash mode of data transfer phase child node below according to these three kinds of states.

State one: wait for transmission state.There are remaining data to transmit in the node of this state.The kind of the frame that now node is likely received has: RTS, DATA, READY, COMPETE, CTS, STOP, re-transmission and ACK; The frame that may send is RTS.Wherein, the structure of READY frame and each field meaning are as shown in table 3:

Table 3

Field name	Effect
		fun	Function field, is fixed as 2
layer	Father node layer information
		parent_id	Father node numbering
region	Area information

The structure of COMPETE frame and each field meaning are as shown in table 4:

Table 4

Field name	Effect
		fun	Function field, is defaulted as 10
layer	Father node layer information

parent_id

Send the father node numbering of COMPETE frame

The structure of CTS frame and each field meaning are as shown in table 5:

Table 5

Field name	Function
		fun	Function field, is defaulted as 4
layer	Sending node layer information
		des_child_id	Object child node numbering
res_parent_id	Send the father node numbering of CTS frame

The structure of STOP frame and each field meaning are as shown in table 6:

Table 6

Field name	Function
		fun	Function field, is defaulted as 5
layer	Sending node layer information
		des_child_id	Object child node numbering
res_parent_id	Send the father node numbering of Stop frame

The structure of ACK frame and each field meaning are as shown in table 7:

Table 7

Field name	Function
		fun	Function field, is defaulted as 8
layer	Sending node layer information
		des_child_id	Object child node numbering
recv_seq	The frame number of confirming
		retrans_info	Need the relevant information of retransmission frame
NAV	Channel holding time indication information

The structure of RTS frame and each field meaning are as shown in table 8:

Table 8

Field name

Function

fun	Function field, is defaulted as 6
		layer	Sending node layer information
data	Data
		des_parent_id	Object father node numbering
res_child_id	Source child node numbering
		seq	Send sequence number
NAV	Channel holding time indication information

Particularly, waiting for that under transmission state, node is according to following method work.

If receive RTS frame, verify the person of sending of this frame.If the person's of sending priority ratio oneself is high, is just busy by corresponding channel tag, and postpones transmission RTS.

If receive DATA frame, verify the person of sending of this frame.If the person's of sending priority ratio oneself is high, is just busy by corresponding channel tag, and postpones transmission RTS.

The effect of READY frame is that the work of notice lower level node formally starts, and is equivalent to initial CTS.The transmitting-receiving of READY frame makes to spread all over fast the whole network from the information of starting working of aggregation node.Receive the child node of this frame and do two work:

1, the READY frame that generates oneself, sends to lower level node, notifies their communication to start.

If 2 have information to transmit, so just generate RTS frame, in the time that meeting, transmission condition sends to upper layer node, and the effect of this frame is that notice father node oneself has been ready to transmit transmission of data, request access channel.

3,, in the time that node belongs to " interregional node " or there is no child node, do not carry out above-mentioned the 1st point.

The effect of CTS frame is the success of father node notice child node channel contention, can send Frame.The node that receives CTS frame can do following work:

1, verify the person of sending of this frame, if father node is issued oneself, so just send immediately data.

2 if father node is issued other child node, represents channel contention failure, and father node state is made as busy.

3 if pseudo-father node is sent, and illustrates that pseudo-father node will transmit data, and so pseudo-father node state is made as busy.

The effect of STOP frame is that father node has been received the RTS that pseudo-child node that priority is higher is sent, and must notify the child node of oneself to stop transmitting data.The node that receives STOP frame can do following work:

1, the person of sending of checking frame, if father node is sent, illustrates that the node of higher priority has sent request of data, and father node state is made as busy.

2 if pseudo-father node is sent, and illustrates that pseudo-father node has stopped transfer of data, so pseudo-father node state is made as to the free time.

ACK frame is father node in the confirmation successfully having received after the Frame that child node sends.When node is waiting for that transmission state while having received ACK, has two kinds of situations: father node is sent, or pseudo-father node sends, and at this moment to have listened to channel be busy to node, and corresponding channel status is made as busy.If receive the COMPETE frame of father node or pseudo-father node, and detect current all channel no signal transmission, corresponding channel status is made as to the free time.Father node and pseudo-father node, all in idle condition, show that corresponding channel is current in idle condition.

Below be also two kinds of same sections of controlling crash mode, no matter network is in which kind of crash mode, node is all worked in a manner described under wait transmission state.And be two kinds of different pieces of controlling crash mode lower node working method below:

Under receiving terminal control crash mode, the effect of COMPETE frame is that father node notifies child node channel in idle condition, can send RTS frame.The node of receiving COMPETE frame can do following work:

1, check " parentid " field, if father node is sent, just father node state is made as to the free time, expression can contention.If pseudo-father node is sent, just pseudo-father node state is made as to the free time.

If 2 father nodes and pseudo-father node, all in idle condition, just send RTS frame contention channel.

If 3 nodes belong to " interregional node ", and not application " control information narrow band transmission mode ", and " interregional adjacent node " place number of plies of this node is with own identical or differ 3 integral multiple (utilizing identical frequency channels to carry out communication), when 2 condition is satisfied, also to inquire about the priority of " interregional adjacent node " so and whether in idle condition.In the time that the priority ratio of this node every other " interregional adjacent node " is all high, (numbering is minimum), sends RTS contention channel so immediately; When the priority of this node is not while being the highest, send immediately RTS contention channel during all in idle condition at " the interregional adjacent node " of high priority.

Under transmitting terminal control crash mode, difference mainly contains 4:

1, COMPETE frame is cancelled.

2, similar with the virtual carrier monitoring mechanism of MACA, NAV value of node maintenance, the effect of this value is how long the transmitting procedure in the current channel of instruction can finish in addition.

3,, under this mode of operation, the condition that node sends RTS becomes: current Channel Detection is that free time and NAV value are 0.

4, under this mode of operation, DATA, two kinds of frames of ACK carry special " NAV " field, when node is intercepted channel, after the value in " NAV " field is processed, preserve.But different from the virtual carrier monitoring in MACA agreement, " NAV " field will be through just reaching the predicted channel effect in idle moment to the correction of propagation delay.The applied correction formula of this agreement can be expressed as:

${\mathrm{NAV}}_{\mathrm{left}}=\min ({\mathrm{NAV}}_{\mathrm{rcv}}-\frac{D_{\mathrm{rcv}}+D_{\mathrm{des}}}{V_s}+T_g)$

Wherein, NAV _leftbe the NAV value in node this locality of monitor channel just, this value is to represent that node can send RTS contention channel at 0 o'clock; NAV _rcvit is NAV " field " value in DATA or the ACK frame receiving; D _rcvbe this node of estimating of the amplitude of the signal received by receiver and send the distance between signal node; D _desto receive the distance between this node that the amplitude of signal estimates and the node that will communicate by receipts machine; V _sthe speed of acoustical signal under the Underwater Acoustic Environment of network place; T _git is the guard time interval of introducing in order to prevent from calculating mistake.

State two: transmission state.Node in this state is to father node transmission data.The kind of the frame that at this moment may receive has following 3 kinds: ACK frame, STOP frame, re-transmission require frame, DATA frame, ACK frame; The frame that may send has DATA frame, FINISH frame.DATA, FINISH frame format and each field effect as Figure 13,14 and table 9,10 as shown in.Wherein, DATA frame format and each field effect are as shown in table 9:

Table 9

Field name	Function
		fun	Function field, is defaulted as 6
layer	Sending node layer information
		data	Data
des_parent_id	Object father node numbering
		res_child_id	Source child node numbering
seq	Send sequence number
		NAV	Channel holding time indication information

FINISH frame format and each field effect are as shown in table 10:

Table 10

Field name	Effect
		fun	Function field, is defaulted as 7
layer	Send child node layer information
		des_parent_id	Object father node numbering

Under transmission state, two kinds of same sections of controlling crash mode comprise:

When child node is in the time that transmission state is received ACK, may be only that father node is sent.At this moment node can be checked the retransmission list of oneself.If this frame is the frame through retransmitting, remove so the record in retransmission list; If this frame is the normal ACK of frame according to the order of sequence, represent so to send successfully, prepare to send next time.In above two kinds of situations, all send window numerical value will be added to one, expression can not have the in the situation that of a confirmation multiple Frame again.

If receive STOP frame, judge the person of sending.If pseudo-father node is sent, represent that pseudo-father node has stopped the transmission of oneself, for priority node has been abdicated channel.Now this node only need be made as busy by pseudo-father node state.If this frame from father node, shows to have the transmission of high priority to take channel, must carve the transmission state that stops.

When node is received DATA frame or RTS frame, check the person of sending, if the higher node of priority is sent, illustrate that now common channel is shared by the transmission of higher priority, send immediately FINISH frame.

If receiving to retransmit requires frame, resend according to the sequence number in retransmission frame.

Can send Frame (DATA) and complete frame (FINISH) at transmission state node.Frame length compared with other frames obviously lengthens, and reason is that it has a data field, carries the data that upper strata will be transmitted.After all Frames are all successfully transmitted, node can send FINISH frame, notifies upper layer node transmission complete, can start the contention of next round.

Two kinds of different pieces of controlling crash mode comprise:

While sending Frame (DATA), transmitting terminal control collision mode will be added " NAV " field in frame, and this field value is illustrated in the node of transmission data and it seems, completes the elapsed time that transfer of data also needs.This agreement specified the concept of transmission be father node receive that child node sends be transmitted (FINISH) frame.Therefore the formula of the calculating NAV that, the agreement of the present embodiment is taked is as follows:

${\mathrm{NAV}}_{\mathrm{data}}=\frac{{N_{\mathrm{left}}(t_p+t_g)V_s+3D}_{\mathrm{est}}}{V_s}+T_g$

Wherein, NAVd _atait is the NAV value that will be included in Frame (DATA); N _leftit is the data frame number that transmitting terminal is also left; t _pto send the frame data time used; t _gthe interval time in the middle of transmission two frame data, assignment as the case may be; D _estthe distance between sending node and receiving node, can be by the strength estimation of reception signal out; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _git is the guard time interval of introducing in order to prevent from calculating mistake.

It is worthy of note, N _leftvalue to dynamically update according to the content of the ACK receiving.In ACK frame, carry the information that needs the frame retransmitting, number and the N of the frame that receiving node retransmits needs _leftvalue is added, as new N _leftvalue.

State three: completion status.In the time that child node remains the frame number that will send out and is 0, automatically enter completion status.Entering after state, if receive that the RTS frame that lower level node is sent can return to preparation transmission state.After the data of all child nodes have all forwarded, carry out dormancy to save the node energy at reasonable time node.

Below, the main handling process of introducing certain node under a kind of preferred receiving terminal control crash mode and upload to its father node information in conjunction with Figure 18, comprises the following steps:

1801) node obtains local detection data, and receives the data of lower level node, when these data accumulations are to a certain extent time, determines that this node will serve as child node uploading data.

1802) described child node enters " wait transmission state ".

1803) described child node is intercepted channel, in the time receiving the COMPETE frame that father node sends, enters step 1804), when the frame of receiving is not that father node sends, enter step 1810).

1804) child node sends RTS frame to father node, request transmission information.

1805) continue to intercept channel, in the time receiving the CTS frame that sends to other nodes, get back to step 1802), in the time receiving father node and send to the CTS frame of oneself, enter step 1806)

1806) this child node enters (or maintaining) transmission state, and under transmission state, child node need to be upgraded according to the retrans_info field in the ACK frame of father node the number of residue frame.

1807) whether whole end of transmission of the data that judge child node, is judged as NO, and enters step 1808, is judged as YES, and enters step 1809).

1808) intercept channel, in the time receiving the ACK frame that father node is sent, get back to step 1806), in the time receiving the STOP frame that father node is sent, get back to step 1802).

1809) child node sends FINISH frame, enters the state of being transmitted (above described in completion status).

1810) whether the sender who judges the frame that this child node receives is the node with higher priority, if the judgment is No, gets back to step 1803), if the judgment is Yes, enter step 1811).

1811) channel of its uploading data of child node is set to busy state, get back to step 1802), in this step, there is a kind of exception, when pseudo-father node is sent if what this child node was received is STOP frame, pseudo-father node state is made as to idle condition.

Below, the main handling process of introducing certain node under a kind of preferred transmitting terminal control crash mode and upload to its father node information in conjunction with Figure 19, comprises the following steps:

1901) node obtains local detection data, and receives the data of lower level node, when these data accumulations are to a certain extent time, determines that this node will serve as child node uploading data.

1902) described child node enters " wait transmission state ".

1903) described child node is intercepted channel, in the time being 0 without the signal that transmitting and NAV value in channel, enters step 1904), when there being signal (being Frame or control frame) to transmit in channel, enter step 1910).In this step, child node also needs to upgrade NAV value.

${\mathrm{NAV}}_{\mathrm{left}}=\min ({\mathrm{NAV}}_{\mathrm{rcv}}-\frac{D_{\mathrm{rcv}}+D_{\mathrm{des}}}{V_s}+T_g)$

Wherein, NAV _leftbe the NAV value in node this locality of monitor channel just, this value is to represent that node can send RTS contention channel at 0 o'clock; NAV _rcvit is NAV " field " value in DATA or the ACK frame receiving; D _rcvbe this node of estimating of the amplitude of the signal received by receiver and send the distance between signal node; D _desto receive the distance between this node that the amplitude of signal estimates and the node that will communicate by receipts machine; V _sthe speed of acoustical signal under the Underwater Acoustic Environment of network place; T _git is the guard time interval of introducing in order to prevent from calculating mistake.

1904) child node sends RTS frame to father node, request transmission information.

1905) continue to intercept channel, in the time receiving the CTS frame that sends to other nodes, get back to step 1902), in the time receiving father node and send to the CTS frame of oneself, enter step 1906)

1906) this child node enters (or maintaining) transmission state, and under transmission state, child node need to be upgraded according to the retrans_info field in the ACK frame of father node the number of residue frame.

1907) whether whole end of transmission of the data that judge child node, is judged as NO, and enters step 1908, is judged as YES, and enters step 1909).

1908) intercept channel, in the time receiving the ACK frame that father node is sent, get back to step 1906), in the time receiving the STOP frame that father node is sent, get back to step 1902).

1909) child node sends FINISH frame, enters the state of being transmitted (above described in completion status).

1910) whether the sender who judges the frame that this child node receives is the node with higher priority, if the judgment is No, gets back to step 1903), if the judgment is Yes, enter step 1911).

1911) channel of its uploading data of child node is set to busy state, get back to step 1902), in this step, there is a kind of exception, when pseudo-father node is sent if what this child node was received is STOP frame, pseudo-father node state is made as to idle condition.

6.2, father node receives data

At data transfer phase, the father node that receives data has four kinds of states: prepare accepting state, accepting state, halted state, completion status.Jump condition between each state as shown in figure 15.In the agreement of the present embodiment, there are receiving terminal control collision and two kinds of patterns of transmitting terminal control collision, the concrete running of these two kinds of patterns is distinguished to some extent.Just analyze the data processing scheme of data transfer phase child node under two kinds of different modes according to above-mentioned four kinds of states below.

State one: prepare accepting state.This state, from receiving the FINISH frame of lower level node, finishes to receiving Frame.The frame that may receive has RTS, DATA frame; The frame that may send has CTS, STOP and COMPETE frame.

Prepare under accepting state, two kinds of same sections of controlling crash mode comprise:

After receiving RTS, process in two kinds of situation:

If 1 receives the RTS frame that child node is sent, father node, taking time order and function order as standard, sends CTS frame to the RTS receiving at first, allows corresponding child node to send data; From total_num field, take out and record total number of frames simultaneously; To the Ignore All of each RTS frame of receiving successively thereafter.

If 2 receive the RTS frame that in pseudo-child node or region, pseudo-child node is sent, mean that this is the channel requisition of higher priority.Father node will be kept out of the way with the transmission to high priority the child node transmission STOP frame of lower floor in this case, starts and keeps out of the way timer simultaneously, now enters halted state.

Receive DATA frame in two kinds of situation:

1 if the DATA frame that child node is sent, and this is normal situation, directly enters accepting state.

2 if the DATA frame that in pseudo-child node or region, pseudo-child node is sent, and this situation is that father node could not be received the RTS of pseudo-child node due under certain special state, therefore sends STOP frame to child node and dodges.If this occurs, father node should be reissued STOP frame to child node and dodge, and starts and keeps out of the way timer simultaneously, enters halted state.

Two kinds of different pieces of controlling collision mode comprise:

1, in receiving terminal control collision mode, node can check the same node layer table of oneself, if higher than own priority with having in node layer, or " pseudo-child node list in region " is non-NULL, want so delayed delivery COMPETE frame, the time of delay can be made as signal by 2.5 times of the average distance time used between two nodes.In the mode of transmitting terminal control collision, father node is being received delayed delivery CTS after the RTS of lower floor, can be made as signal time of delay by 1.5 times of the average distance time used between two nodes.

2, in receiving terminal control collision mode, enter and wait for that the node of accepting state can send COMPETE frame, prompting lower level node can carry out the contention of channel.And in transmitting terminal control collision mode, COMPETE frame mechanism is deleted.

State two: accepting state.Accepting state is from receiving correct DATA frame, to receiving FINISH frame end.The frame that may receive has FINISH, DATA, RTS.The frame that may send has STOP, ACK.

Two kinds of same sections of controlling collision mode comprise:

When father node receives DATA frame in two kinds of situation:

1 if the DATA frame that child node is sent, and this is normal situation, replys ACK confirm according to sending sequence number accordingly.If the DATA frame number generation saltus step receiving, has missed some Frame in the middle of representing.Now node can deposit the sequence number of the frame of loss in loss storage, and inserts retransmission information in the retrans_info of ACK frame field, and this ACK is sent to child node.The frame number that father node utilization has been received calculates the sequence number set of the Frame of also not receiving with these two values of totalframes amount that the total_num field from RTS frame is taken out, and is stored in loss register.

2 if the DATA frame that pseudo-child node is sent, this situation be to send more lately due to the RTS of pseudo-child node, there is collision in the data of sending with child node.Now father node could not be received high priority RTS and child node do not sent to STOP frame, causes data that the most serious collision has occurred.Now, owing to there is no correct ACK confirmation, child node send window exhausts, and suspend transmission, and the communication of pseudo-child node normally carries out, so be bound to receive the Frame that pseudo-child node is sent after collision a period of time.Now to send STOP frame to child node, enter halted state.

Receiving RTS is the special case causing due to improper time delay, is similar to the second situation of receiving DATA frame, sends STOP frame, enters halted state.

Two kinds of different pieces of controlling collision mode comprise:

If 1 father node receives FINISH frame, the child node of interior busy channel of expression a period of time has completed transfer of data and has surrendered the right to occupation of channel.Under receiving terminal control crash mode, father node will send COMPETE frame to lower floor, notifies their channels idle, can carry out contention.Under transmitting terminal control crash mode, COMPETE frame mechanism is deleted, and while receiving FINISH frame, NAV value is clear 0, replys an ACK frame that NAV value is 0 to lower level node simultaneously.

2, father node is in the time sending acknowledgement frame (ACK), transmitting terminal control crash mode will be added " NAV " field (not needing to carry out this processing under receiving terminal control crash mode) in frame, this field value is illustrated in the node of reception data and it seems, completes the elapsed time that transfer of data also needs.This agreement specified the concept of transmission be father node receive that child node sends be transmitted (FINISH) frame.Therefore the formula of the calculating NAV, taking in the agreement of the present embodiment is as follows:

${\mathrm{NAV}}_{\mathrm{ack}}={\mathrm{NAV}}_{\mathrm{data}}-\frac{D_{\mathrm{est}}}{V_s}+T_g$

Wherein, NAV _ackit is the NAV value that will be included in acknowledgement frame (ACK); NAV _datait is the NAV field value in data (DATA) frame sent of child node that father node receives; D _estthe distance between sending node and receiving node, can be by the strength estimation of reception signal out; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _git is the guard time interval of introducing in order to prevent from calculating mistake.

State three: halted state.Halted state is that object is to avoid the transfer of data of high priority, to avoid collision because the RTS or the DATA frame that have received high priority cause.When father node received FINISH frame or keep out of the way overtime after halted state finish.The frame that may receive is DATA and FINISH frame; The frame that may send only has COMPETE frame.

May receive the DATA frame of child node or pseudo-child node in halted state.But no matter which kind of, father node all can keep silent (not sending ACK).Father node can record the reception number of pseudo-child node frame, for halted state releasing mechanism provides parameter.

FINISH frame only may pseudo-child node transmit, because interrupted before the transfer of data of child node.After receiving FINISH frame, enter preparation accepting state, and send at once COMPETE frame.

There is a particular point to stress in halted state, keep out of the way exactly failure problem.When father node receives after the RTS of high priority, be bound to send STOP frame and keep out of the way at once.But because the feature of this agreement is that each node is only preserved local topology information, cannot learn and whether have the node of higher priority contention channel, the node that high priority occurs possibly will be kept out of the way the data transmission of higher priority.So this agreement has adopted one to keep out of the way to be avoided insignificant from releasing mechanism and keeps out of the way for a long time.Specific practice is: after father node sends STOP frame, start and keep out of the way timer at once, after the suitable time, timer initiation judges process, the number of the pseudo-child node DATA frame that inspection receives, if (not being made as 0 is because node had probably received CTS before keeping out of the way to be less than a certain threshold value, and send a small amount of DATA frame), be judged as this priority node and be also forced to carry out keep out of the way.Now keep out of the way unsuccessfully, finish halted state and send COMPETE frame to allow child node contention channel again.Do like this resource utilization that has very effectively improved network, improved throughput.

State four: completion status.In preparation accepting state, if do not have lower level node to send RTS, father node enters completion status.

Below, the main handling process of introducing certain node under a kind of preferred receiving terminal control crash mode and receive its lower level node uploading data in conjunction with Figure 20, comprises the following steps:

2001) certain node enters " preparation accepting state ".

2002) this node sends COMPETE frame to lower level node.

2003) intercept channel, in the time receiving the RTS frame that child node sends, enter portion's step 2004), in the time receiving the RTS frame that seat node sends, enter step 2007), in the time not receiving RTS frame in certain hour, illustrate that this transmitting procedure finishes, and enters step 2008).

2004) send CTS frame to the child node of lower floor, enter accepting state.

2005) intercept channel, in the time receiving the DATA frame that child node is sent, enter step 2006), in the time receiving with layer ACK frame that higher priority node sends or CTS frame, enter step 2007), in the time receiving DATA frame that pseudo-child node is sent or CTS frame, also enter step 2007), in the time receiving the FINISH frame that child node is sent, get back to step 2001).

2006) send ACK frame and give node.

2007) send STOP frame to child node, enter halted state.And child node is kept out of the way.

2008) enter completion status.

Below, the main handling process of introducing certain node under a kind of preferred transmitting terminal control crash mode and receive its lower level node uploading data in conjunction with Figure 21, comprises the following steps:

2101) certain node enters " preparation accepting state ", carries out 2103) step.

2103) intercept channel, in the time receiving the RTS frame that child node sends, enter portion's step 2104), in the time receiving the RTS frame that seat node sends, enter step 2107), in the time not receiving RTS frame in certain hour, illustrate that this transmitting procedure finishes, and enters step 2108).Note not comprising in this handling process the step of transmission COMPETE frame.

2104) send CTS frame to the child node of lower floor, enter accepting state.

2105) intercept channel, in the time receiving the DATA frame that child node is sent, enter step 2106), in the time receiving DATA frame that pseudo-child node is sent or RTS frame, enter step 2007), in the time receiving the FINISH frame that child node is sent, enter step 2109).

2106) send ACK frame to child node.

2107) send STOP frame to child node, enter halted state.And child node is kept out of the way.

2108) enter completion status.

2109) send an ACK frame that NAV value is 0 to lower level node, get back to step 2101).

Seven, about specific question

In actual applications, the irregular sensor network that the present embodiment provides also can run into some special circumstances.Availability in these the present embodiment schemes is in particular cases discussed respectively below.

1) level problem in region

The first situation, as shown in figure 29.Efficient communication scope between circle representation node, the communication band of all nodes of topological initial phase is identical.No. 10 nodes are aggregation node, and 7,8, No. 9 nodes are common sensor node.No. 7 nodes, within the communication range of No. 10 nodes, are initialized to 1 node layer.Although No. 8 nodes from No. 7 nodes very close to, outside No. 10 node communication scopes, be not initialised.No. 7 node produces after correct topological initialization information, sends towards periphery, and 8, No. 9 two nodes are both initialized to 2 node layers.8, 9 liang of nodes can produce the topological initialization information of response equally, although but two nodes are all within the other side's communication range, but according to the 7th point in embodiment Part III in specification " definite method of pass-through mode and forwarding priority ", 8, 9 liang of nodes are being received the information that can't change place level after the other side's topological initialization information, still think it oneself is 2 node layers, the other side's nodal scheme and hierarchical information are stored in to (referring to the 2nd point in embodiment Part V " topology initializing method ") in same node layer list simultaneously.

The second situation, as shown in figure 30.Suppose that node 4 damages, at this moment cause the topological initialization procedure that should be initiated by 1,2 liang of node in the network layer second layer No. 9 node to be initialized as the 3rd node layer, and think that No. 1 node is its father node (node serial number is little, and priority is higher) for No. 9.No. 3 nodes are also the 3rd floor by No. 1 node initializing simultaneously.After No. 9 node is initialised, can send topological initialization information to lower floor, even if now No. 3 nodes have received that this information can not be initialized to the 4th node layer yet, because will think that the less upper layer node of level is father node according to No. 3 nodes of the regulation of protocol forward priority (referring to the 7th point in embodiment Part III " definite method of pass-through mode and forwarding priority ").The second situation has illustrated that this topology initialization mode still can normally work in the situation that some nodes damages, and level mistake is difficult for propagating (the level mistake of No. 9 nodes does not cause the level mistake of No. 3 nodes).

The third situation, as shown in figure 31.Topology initialization path 10,7,1,3,4,5,6 is in good condition, and 10,8,2 paths are just set up for a certain reason for a long time.Complicated situation is: now No. 6 nodes send topological initialization information to No. 2 nodes, and No. 2 nodes send topological initialization information to No. 6 nodes simultaneously.Specify according to agreement, No. 2 node is processed the topological initialization information of No. 6 nodes, but can not change own place level, now can be by the information storage of No. 6 nodes (the 6th point in referring to embodiment Part V " topology initializing method ") in " pseudo-father node list in region ".On the other hand, No. 6 node is processed the topological initialization information of No. 2 nodes, because No. 2 node place level is less, priority higher (referring to the 7th point in embodiment Part III " definite method of pass-through mode and forwarding priority "), so No. 2 nodes of No. 6 node identifications are father node, and change the place level of oneself into the 3rd layer, and send it back complex information and new topological information generated (referring to the 7th point in embodiment Part V " topology initializing method ").No. 2 node receives No. 6 nodes to after the return information of oneself, No. 6 nodes are deleted from " pseudo-father node list in region ", and No. 6 nodes are stored in to (referring to the 9th point in embodiment Part V " topology initializing method ") in child node list.No. 5 nodes have received No. 6 equally to the topological return information of No. 2, according to protocol contents, No. 6 nodes are stored in to (referring to the 10th point in embodiment Part V " topology initializing method ") in " pseudo-child node list in region ".The new topological information generated of No. 6 node transmissions is ignored (referring to the 7th point in embodiment Part V " topology initializing method " by No. 2 (referring to the 6th point in embodiment Part V " topology initializing method ") and No. 5 nodes.So far, node 6 is as " the pseudo-child node in region " of No. 5 nodes, and node 5 is as " the pseudo-father node in region " of node 6, and topology information initialization is successful.

Other situations are all simple than what discussed, repeat no more.

No. 5 nodes in Figure 31 are not still explained as the reasonability of five node layers as the child node (four floor) of No. 6 nodes: although can be by communication to aggregation node through hop count still less as four node layers, but as set up sooner than 10,8,2 paths in situation 10,7,1,3,4,5,6 paths in hypothesis, illustrate that the former communication is all right, although the latter's hop count is few, but it is poor to transmit situation, so unnecessarily pursue simply less hop count.

Solution to the conflict of frequency band when level problem in region is as follows:

Topological structure as shown in figure 31, the separation of data transfer direction between No. 5 and No. 6, No. 5 to No. 4 with frequency range 2 transmission of informations, No. 6 to No. 2 with frequency range 3 transmission of informations, between No. 5 and No. 6 without the transmission of significant information.In the case, due to frequency layered reuse mechanism role, the information transmission between two group nodes is not affected.In fact, as long as two adjacent sending nodes need not same frequency range transmission information just can not influence each other.Even and two nodes of working as adjacent transmission information have shared same frequency channels, as long as take control information narrow band transmission mechanism, there is not interactional problem (if desired can explain in detail) yet.Present problem concentrates on adjacent two transmission nodes and just transmits data and there is no control information narrow band transmission mechanism by identical frequency band.We suppose that 5,6 liang of node identical frequency band of Figure 31 send data, and now No. 4 nodes probably produce and conflict to the return information such as ACK of No. 5 in the time arriving No. 5 nodes with the data message of issuing No. 2 for No. 6.Solution is to set transmission priority.According to the transmission priority regulation (referring to the 11st point in embodiment Part III " definite method of pass-through mode and forwarding priority ") of agreement, in region, pseudo-byte point has higher transmission priority.In this case, No. 5 nodes are in the time receiving No. 6 nodes and issue the DATA of No. 2 or RTS frame, stop immediately transmission, send FINISH frame to upper strata, to abdicate the taking of channel (referring to the related protocol content of the accepting state of recording in the 6.1st in embodiment Part VI " data transmission method ").

2) interregional fringe node problem

Shown in figure 32, when agreement is after node lays and added the support of poly concourse nodes in mode, there will be the node of all receiving topological initial information at the edge of two network areas, as shown in the node of Figure 32 intermediate cam mark.In topological initialization procedure, in the processing mode of interregional fringe node and region, level problem is similar, be that the processing of interregional fringe node relates to the concept in " region ", the network that different aggregation nodes forms belongs to different " regions ", can receive from the node of the topological initialization information of zones of different and be called " interregional node ", interregional node will stop continuing to send topological initialization information.Divide two kinds of situations of initialization topology information and information transmission to describe below:

When initialization topology information, as shown in figure 33, typical case is that 4,6,5,2 four nodes have sent topological initialization information to No. 3 nodes simultaneously.Suppose that No. 3 nodes receive sequence of information and get rid of total following two kinds of same case: " 4,6,5,2 ", " 5,2,4,6 ", analyze one by one below.When " 4,6,5,2 ", 6 node layers that first No. 3 nodes are region 1 by No. 4 node initializing, father node is No. 4, and sends return information.Receive after the initialization information of No. 6 when No. 3, ratio has higher priority (referring to the 6th point in embodiment Part III " definite method of pass-through mode and forwarding priority ") for No. 6 due to No. 4, so regard as pseudo-father node by No. 6 No. 3.When receiving for No. 3 after the topological initialization information of No. 5 and No. 2, according to agreement (referring to the 13rd point in embodiment Part III " definite method of pass-through mode and forwarding priority " (referring to the 8th point in embodiment Part V " topology initializing method "), No. 3 by No. 5 with regard as " interregional pseudo-father node " for No. 2.The return information of No. 3 also will all be received by 4 nodes.To think that No. 3 for child node for No. 4; To think that No. 3 for pseudo-child node for No. 6; No. 5 with all think that No. 3 for " interregional pseudo-child node " (referring to the 11st point in embodiment Part V " topology initializing method ") for No. 2.When " 5,2,4,6 ", No. 3 nodes will be initialized to the child node of No. 2 nodes in region 2, and other and a upper situation are similar.

In message transmitting procedure, similar with the transmission priority situation in region, when adopting after control information narrow band transmission mechanism, interregional node there will not be interference problem in message transmitting procedure.In the time not adopting control information narrow band transmission mechanism, as shown in figure 34.No. 3 nodes are 3 node layers in region 1, and No. 2 is 3 node layers in region 2 with No. 5.In topological initialization procedure, be for No. 3 No. 5 with " the interregional pseudo-child node " of No. 2, No. 5 with " the interregional pseudo-father node " that be No. 3 for No. 2.Transmitting procedure starts rear according to transmission priority rule (referring to the 8th point in embodiment Part III " definite method of pass-through mode and forwarding priority "), and the transmission of No. 3 nodes has higher priority.By analysis above, in the time having interregional fringe node problem to occur, the agreement of the present embodiment all can normally be moved as seen.

It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described.Although the present invention is had been described in detail with reference to embodiment, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is modified or is equal to replacement, do not depart from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.

Claims (10)

1. the data transmission method for underwater sound sensor network system, described underwater sound sensor network system comprises aggregation node and sensor node, wherein, aggregation node is the 0th node layer, and distance between the aggregation node sensor node within the scope of efficient communication is the 1st node layer; For each i node layer, remove upper layer node and with outside node layer, the sensor node with the distance of this i node layer within the scope of efficient communication is i+1 node layer, and wherein i is positive integer, and i node layer is the upper layer node of i+1 node layer;

Described data transmission method comprises:

1) aggregation node sends control information to lower level node;

2) each sensor node sends or forwards control information to lower floor;

3) each sensor node uploads to upper layer node the data that this node gathers, and forwards the received data of being uploaded by lower level node of this node to upper layer node; At sensor node, during to its upper layer node uploading data, receiving terminal is that its each received Frame returns to an acknowledgement frame, and it is N that transmitting terminal arranges length _twsend window, transmitting terminal, in the time not receiving acknowledgement frame corresponding to a certain Frame, sends taking this Frame as initial N at most more continuously _twindividual Frame;

Wherein, each sensor node adopts the media access way based on competition, contention channel as required.

2. data transmission method according to claim 1, is characterized in that, in described step 3), for each transmitting terminal, send window is set respectively, the length of transmitting terminal window

$N_{\mathrm{tw}}=\frac{{2D}_{\mathrm{est}}+V_s{T}_g}{V_s(t_p+t_g)}$

Wherein, D _estit is the distance between sending node and receiving node; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _gbe for fear of due to estimation inaccurate guard time interval of introducing; t _pto send the frame data time used; t _git is the interval time in the middle of transmission two frame data.

3. data transmission method according to claim 1, it is characterized in that, in described step 3), transmitting terminal retransmits timer and carries out countdown sending all to start when each Frame, retransmits corresponding data frame while meeting following two kinds of conditions are any: 1. transmitting terminal is not received the acknowledgement frame of certain sequence number X Frame and the re-transmission timer value of this frame is kept to 0; 2. transmitting terminal receives the acknowledgement frame of other frames of jump sequence number, and in this acknowledgement frame, has carried the retransmission information of the frame that sequence number is X.

4. data transmission method according to claim 3, is characterized in that, in described step 3), the number of times upper limit of re-transmission is set as 5 times, for a certain Frame, when retransmitting while also not receiving corresponding acknowledgement frame after 5 times, judges that communication link is cut off.

5. data transmission method according to claim 3, is characterized in that, in described step 3), the initial value of described re-transmission timer calculates with following formula:

$T_{\mathrm{left}}=\frac{{2D}_{\mathrm{est}}+V_s{T}_g}{V_s}$

Wherein, T _leftthe initial value that retransmits timer, D _estit is the distance between sending node and receiving node; V _sthe propagation velocity of sound in network institute working water acoustic environment; T _gbe for fear of due to estimation inaccurate guard time interval of introducing.

6. according to the data transmission method described in claim 2 or 5, it is characterized in that, in described step 3), the distance B between sending node and receiving node _estintensity by sensor node received signal calculates.

7. data transmission method according to claim 1, is characterized in that, control information is carried out to redundant transmission.

8. data transmission method according to claim 7, is characterized in that, classifying importance is carried out in described control information, and the number of times of the higher control information redundant retransmission of importance is more.

9. data transmission method according to claim 7, is characterized in that, the Transmission Time Interval of the control frame of two redundant transmission is determined according to the average distance of network intermediate node and the control frame frame length that will transmit.

10. data transmission method according to claim 9, is characterized in that, the time interval of the control frame of two redundant transmission is minimum value minT _sepwith maximum maxT _sepbetween random number;

minTse _p=2t _p

maxT _sep=3t _p

Wherein, t _prepresent that single transmits the described control frame time used.