CN102263610A

CN102263610A - Data transmission method for acoustic sensor network system

Info

Publication number: CN102263610A
Application number: CN2010101946351A
Authority: CN
Inventors: 隋天宇; 李宇; 黄海宁; 张春华
Original assignee: Institute of Acoustics CAS
Current assignee: Institute of Acoustics CAS
Priority date: 2010-05-28
Filing date: 2010-05-28
Publication date: 2011-11-30

Abstract

The invention provides a data transmission method for acoustic sensor network system. The method comprises the following steps: 1) a sink node sends control information to lower-layer nodes; 2) each sensor node sends or forwards the control information to the lower-layer nodes; and 3) each sensor node uploads data collected by the sensor node to upper-layer nodes and forwards the data uploaded by the lower layer nodes and received by the sensor node to the upper-layer nodes. The invention can meet the requirement of sparse placement mode; each node has a reliable data uploading link; precise synchronization and timing are not required; and the method can be applicable to irregular network shapes. According to the invention, data collision can be controlled to the maximum extent and integrity of the data uploading can be ensured under the objective condition of restricted bandwidth; the sensor has high energy utilization efficiency of the nodes, thereby saving the energy and improving the service life. The invention provides two collision control schemes applicable to different transmission conditions, thus the data transmission efficiency can be effectively improved.

Description

A kind of data transmission method that is used for the water sound sensor network system

Technical field

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

Background technology

Tradition land is formed by being deployed in the surveyed area a large amount of cheap microsensor nodes with wireless sensor network, by the self-organizing system that communication forms with certain topological structure, it have self-organization, dynamic, data-centered, with use characteristics such as closely related.Node in the wireless sensor network can adopt various types of transducers (as sound, light, electricity, heat sensor etc.), with regard to inserting medium, tradition land mostly is to insert medium with the atmosphere with wireless sensor network, and generally adopts the carrier of electromagnetic wave as the transmission data.With regard to topological structure, wireless sensor network mainly contains Star Network, point to point network, self-organizing network and sub-clustering network at present.Above-mentioned existing various topological structures all be difficult to adapt to the submerged applications environment.Its reason is as follows:

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

2, owing to take the sparse mode that lays, the correlation between each node data in the water sound sensor network is very little, does not almost have redundant data, needs therefore to guarantee that each node all has reliable data upload link.In the existing sub-clustering network, the node in the 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.Yet, sparse when laying mode when adopting, can not guarantee that each leader cluster node that elects all has reliable data upload link, so the sub-clustering network does not satisfy the sparse requirement that lays mode yet.

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

4, under water in the sonic transducer network, because factor of natural environment, the position of sensor node can be subjected to bigger 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, present wireless sensor network and data transmission method thereof can't be applicable to the submerged applications environment, need a kind of brand-new water sound sensor network system that can be applicable to the submerged applications environment.And that the water 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 specific question such as be difficult to replenish, existing data transfer mode is difficult to reach requirement even can't be suitable at all, and therefore current pressing for provides a kind of data transmission method that is complementary with the water sound sensor network system.

Summary of the invention

The purpose of this invention is to provide a kind of data transmission method that is used for the water sound sensor network system.

For achieving the above object, the invention provides a kind of data transmission method that is used for the water sound sensor network system, described water sound sensor network system comprises aggregation node and sensor node, wherein, aggregation node is the 0th node layer, and the distance between the aggregation node is the 1st node layer in the efficient communication scope with interior sensor node; For each i node layer, remove upper layer node and with outside the node layer, with the distance of this i node layer be the i+1 node layer in the efficient communication scope with interior sensor node, wherein i is a positive integer, the 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 transmits control information to lower floor;

3) each sensor node is uploaded the data that this node is gathered to upper layer node, and transmits the received data of being uploaded by lower level node of this node to upper layer node.

Wherein, when a node can be communicated by letter with a plurality of upper layer node simultaneously, one of them upper layer node is defined as father node, lower level node is preferentially uploaded data by its father node.

Wherein, described step 3) adopts receiving terminal control crash mode to carry out data upload, comprises following substep:

31) the definite lower level node that need upload data;

32) upper layer node is sent the COMPETE frame;

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

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

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

Wherein, under the receiving terminal control crash mode, described step 3) also comprises following substep:

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

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

Wherein, described step 3) adopts transmitting terminal control crash mode to carry out data upload, comprises following substep:

31) the definite lower level node that need upload data;

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

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

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

Described NAV value real-time update,

{NAV}_{left} = \min ({NAV}_{rcv} - \frac{D_{rcv} + D_{des}}{V_{s}} + T_{g})

Wherein, NAV _LeftBe just in the NAV value of node this locality of monitor channel, this value is to represent that node can send the RTS contention channel at 0 o'clock; NAV _RcvBe the DATA that receives or NAV " field " value in the ACK frame; D _RcvBe this node of estimating of the amplitude of the signal received by receiver and send distance between the signal node; D _DesBe to receive distance between this node that the amplitude of signal estimates and the node that will communicate by the receipts machine; V _sBe the speed of acoustical signal under the underwater sound environment of network place; T _gIt is the guard time interval of introducing in order to prevent to calculate mistake.

Wherein, under the transmitting terminal control crash mode, described step 3) also comprises following substep:

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

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

Wherein, the employed frequency band of described water sound sensor network system comprises first, second, third data message frequency band; If certain node level is N, satisfy N mod 3=0, then this node is 1 category node (mod is for getting remainder operation), satisfy N mod 3=1, then this node is 2 category nodes, satisfy N mod3=2 then this node be 3 category nodes, first, second, third data message frequency band is adopted in 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 respectively.

Wherein, the employed frequency band of described water sound sensor network system also comprises the control information arrowband, and the control information between each node uses the control information arrowband to transmit.

Wherein, when a node can be communicated by letter with a plurality of upper layer node simultaneously, one of them upper layer node is defined as father node, and determines that other upper layer node is pseudo-father node, this node is preferentially uploaded data by its father node.

Wherein, when a node can communicate with a plurality of lower level nodes simultaneously, judge the priority of the father node of each lower level node, when the father node height of the described lower level node of priority ratio of oneself, and the father node of this lower level node is during with node layer, determines the child node of this lower level node for oneself; When the father node of the described lower level node of priority ratio of oneself is low, and the father node of this lower level node is during with 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: the 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 the communication range.

Wherein, described aggregation node number is greater than 1, a zone 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 the zone, pseudo-child node numbering in the zone, 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, each node only need be communicated by letter with a spot of adjacent node among the present invention, satisfies the sparse requirement that lays mode;

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

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

4, the present invention does not have specific (special) requirements to the network shape, applicable to various irregular network shapes;

5, the present invention's control data collision farthest, the integrality of assurance data upload under band-limited objective condition;

6, the efficiency of energy utilization height of sensor node of the present invention can be saved the energy, improves useful life;

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

When 8, the transmission conditions of underwater acoustic channel were relatively poor, the present invention can adopt receiving terminal control crash mode to guarantee data upload efficient.

Description of drawings

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Figure 22 is a kind of information frame frequency band division scheme schematic diagram in the 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 for containing the schematic diagram of a plurality of aggregation node networks in the one embodiment of the invention;

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

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

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

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

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

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

Figure 30 is second kind of situation of the interior level problem in zone in the one embodiment of the invention, the schematic diagram of the initialization issue handling mode that causes under some node damaged condition;

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

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

Figure 33 carries out topological initialized schematic diagram for two Area Nodes in the one embodiment of the invention to fringe node;

Figure 34 is the processing mode schematic diagram when producing disturbed condition in the transmission course in the one embodiment of the invention.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is done to describe further.

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

Wherein, aggregation node is to have than strength reason 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 generally is made up of wired or wireless transmitter module, underwater acoustic communication module, information processing and memory module, energy supply module etc.

Sensor node is underwater information to be detected (as temperature, the salinity degree of depth etc.) can be converted to digital signal and give the node of upper layer node or aggregation node by the underwateracoustic channel transfer, 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 water sound sensor network system of present embodiment is that the center is disposed each sensor node and formed and besiege it ring upon ring the type network with the aggregation node.For making drawing clear, only come the representational level relation with concentric circles simply among Fig. 1, in fact, the level of each node is judged by following method: aggregation node is the 0th node layer, with the distance of aggregation node be the 1st node layer at the underwater sound communication critical distance with interior sensor node; For each i node layer, remove upper layer node and with outside the node layer, with the distance of this i node layer be the i+1 node layer at the underwater sound communication critical distance with interior sensor node, wherein i is a positive integer, i.e. i=1,2,3...... upper layer node is the less node of level number.Should be appreciated that at node to lay the position comparatively accurately the time, the hierarchical relationship that above-mentioned decision rule forms is identical with concentric round hierarchical relationship shown in Figure 1.

Because the node cost of underwateracoustic network is very high, thus can only sparsely lay, in the hope of maximum area coverage is arranged.Therefore, the criteria for classifying between present embodiment layer and the layer is: adjacent level can direct communication, and non-adjacent level (not comprising with layer) can't direct communication.Can realize above-mentioned criterion by distance and node power between the Control Node.Such as, can set the power threshold of each node earlier, for arbitrary node, after receiving underwater sound signal, power threshold as described in being lower than as its power then abandons this underwater sound signal.Owing to the increase of underwater sound signal along with distance decays, therefore all can form the underwater sound communication critical distance naturally between per two nodes in the sensor network, when two internodal distances during smaller or equal to the underwater sound communication critical distance, these two nodes can direct communication, the two is an adjacent node, when two internodal distances during greater than the underwater sound communication critical distance, these two nodes can not direct communication, and the two is non-conterminous node.In the present embodiment, distance (general at a distance of more than the km) far away belongs to sparse network between the node, the data dependence that different nodes are gathered is less, data do not have redundancy, and promptly each node all needs to send data to aggregation node, and the data volume that each node need transmit is bigger.Simultaneously, there is the under-supply problem of energy in sensor node, thus should reduce the communication disruption that signal collision causes as far as possible, to save the energy.

The water sound sensor network system of present embodiment adopts sudden continuously-running duty.Most of times of node are in resting state.When starting working, aggregation node at first 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 all will this node is collected data passes give aggregation node.After the data of all nodes in the network were all finished transmission, all nodes entered resting state.

Divide 7 parts to introduce the various aspects of the water sound sensor network system of present embodiment in detail below.These 6 parts are respectively: definite method of topological structure, medium access control (MAC) method, pass-through mode and forwarding priority, overall work flow process, topological initial method, data transmission method and about the discussion of specific question.

One, topological structure

Present embodiment has adopted topological structure by different level.As shown in Figure 1, the Hierarchical network of present embodiment comprises 2 kinds of nodes: aggregation node and common sensor node.Whole network can be disposed a plurality of aggregation nodes according to actual conditions, and the area information that each aggregation node curing has nothing in common with each other is so that incorporate each sensor node in the correct zone into when topology generates.Present embodiment can also be the center with each aggregation node, forms a plurality of small-scale Hierarchical networks, as shown in figure 23.Fringe node can belong within the particular network scope according to the priority principle (this part will be described below) of the child node in the present embodiment, father node.

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

The distance of utilizing communication is as the standard of dividing level, and 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 identical substantially, is made as A.At receiving terminal, decay to some extent after signal transmits through underwater acoustic channel, the size of decay is the function of 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 the communication process, this coefficient is the function of two euclidean distance between node pair.

In topological forming process, work as A _rAmplitude during less than certain predefined threshold value, receiving node will not done any processing to this signal, this has just guaranteed that the node communication between the adjacent two layers all is within the reliable scope that can guarantee in the topological structure.

Two, medium access control (MAC) method

Present embodiment adopts the medium 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 characteristics of underwater acoustic channel.

(1) in the present embodiment, the employing layering frequency division mechanism of communicating by letter between layer and the layer.Communication (mainly being meant data upload) employed frequency band is divided into three sections between each layer, is respectively first, second, third data message frequency band, and physical planning as shown in figure 26.

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

N?mod?3＝0；

The level of 2 category nodes satisfies

N?mod?3＝1

The level of 3 category nodes satisfies

N?mod?3＝2

First, second, third data message frequency band is adopted in 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 respectively.

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

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

When band resource is not really nervous, the control information arrowband can be set, can make like this with node layer and when receiving, not disturb mutually, can work simultaneously with node layer under many circumstances.

When band resource is nervous, the control information arrowband can be set.At this moment, because the data message that the control information that sends to lower floor with node layer and lower level node are sent can disturb, so can't work simultaneously with the node in mutual communication range of layer in same frequency range.

The medium access control scheme of 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).When adopting transmitting terminal control collision, the control information arrowband must be set.

(2) present embodiment adopts according to the characteristics of network and selects to retransmit ARQ (AutomaticRepeat-reQuest) mechanism, and in this mechanism, data receiver sends after the data not can be at once with this data destroying, but deposits a buffer memory in.When all frames of receiving as the recipient are all correct, judge to receive successfully, just buffer memory is emptied at this moment; Occur wrong or when having lost some frame when receiving terminal detects certain frame, the sequence number of erroneous frame or lost frames is sent to data receiver, transmit leg is retransmitted these Frame.Accordingly, transmit leg will retransmit these information frames that are not identified under the situation of the affirmation information of not receiving the recipient or the jump of confirmation sequence number.

(3) present embodiment also needs to be provided with send window.

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

N_{tw} = \frac{{2 D}_{est} + V_{s} T_{g}}{V_{s} (t_{p} + t_{g})}

N wherein _TwIt is the send window size; D _EstBe the distance between sending node and receiving node, can come out by the strength estimation of received signal; V _sBe the propagation velocity of sound in network institute working water acoustic environment; T _gBe for fear of the guard time interval of introducing, assignment as the case may be owing to estimation is inaccurate; t _pBe to send the used time of frame data; t _gBe the blanking time in the middle of transmission two frame data, assignment as the case may be.

(4) present embodiment has the overtime retransmission mechanism of transmit leg.Transmit leg all starts the re-transmission timer and carries out countdown when sending each Frame.Agreement is defined in retransmitting data frame when following two kinds of conditions are any to be satisfied: 1, be kept to 0 at the ACK that does not receive 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 to have carried sequence number among the ACK be the retransmission information (frame structure of ACK is seen Figure 11) of the frame of X.The number of times of overtime re-transmission in a preferred embodiment is set at 5 times.If also do not receive after surpassing 5 times and reply ACK, just think that communication link is cut off, with error logging and report to the upper strata control program.The initial value of the re-transmission timer of present embodiment calculates with following formula:

T_{left} = \frac{{2 D}_{est} + V_{s} T_{g}}{V_{s}}

Wherein, T _LeftBe the initial value that retransmits timer, D _EstBe the distance between sending node and receiving node, can come out by the strength estimation of received signal; V _sBe the propagation velocity of sound in network institute working water acoustic environment; T _gBe for fear of the guard time interval of introducing, assignment as the case may be owing to estimation is inaccurate.

(5) present embodiment carries out redundant transmission to control information.For guaranteeing the correct transmission and the processing of important control information, take into account the reasonable utilization of Internet resources simultaneously, present embodiment carries out classifying importance to different information frames, the number of times that decision on this basis repeats to transmit, and the specific implementation method that is adopted 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 _pExpression transmits the used time of certain control frame.During 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 lower level node is want to give the aggregation node just must be via the forwarding of upper layer node message transmission, promptly the N node layer is striven data information transfer to the N-1 node layer in the network work process.

As shown in Figure 2, because the characteristics of level type topological structure, in most of the cases each node can communicate with 2 or a plurality of upper layer node, for avoiding channel confliction and saving resource, is necessary to specify the node of bearing the forwarding task by certain priority rule.

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

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

2, in same node layer, node serial number is more little, and priority is big more.

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

4, in the process of contention channel, be in the node of preparing accepting state and will judge whether have highlyer in the own same node layer than own priority, if having, then postpone a period of time to send COMPETE or CTS frame, with the communication of assurance priority node.The explanation about father node preparation accepting state of the middle vide infra data transmission method part of detailed content.

5, in the adjacent two layers node, send child node and father node that data and the node that receives data are called the other side, promptly the data sent of child node are responsible for forwarding by father node.

6, when node can be communicated by letter with a plurality of upper layer node simultaneously, that node serial number is less is called father node, assert that simultaneously other upper layer node is pseudo-father node, as shown in Figure 3.

7, if when certain node is simultaneously adjacent with two or more nodes with regional different levels, only assert the father node that is of node level minimum, the shortest with the guarantee information transmission path.

8, in the interregional transmission course, interregional pseudo-child node has higher priority.

9, node is not handled the topological initialization information of sending with the node of oneself setting up topological hierarchical relationship, to avoid repetition initialization phenomenon (it is because network topology is unreasonable or node damages " spiral " initialization phenomenon that causes that this situation occurs).

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

11, in the zone in the transmission course, the transmission of the interior pseudo-child node in zone has higher priority.

12, in transmission course, if occur two with node layer during with same frequency range transmission information, node serial number is less higher priority.

13, the affiliated area of interregional node is determined by first topology that receives generation information.

14, when transmission, child node just can be sent the channel contention request when only the channel of pseudo-child node is all idle in judging father node and all pseudo-father nodes, zone.

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

16, according to the data-centered characteristics of sensor network, this agreement will not paid attention to the fairness of each node contention to channel.

Four, overall work flow process

According to present embodiment, at " node level type lays network ", according to the described Rulemaking procotol of last branch, 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 present embodiment mainly is divided into topological initial phase and data transfer phase.Introduce respectively below:

1, topological initial phase

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

2, data transfer phase

At data transfer phase, the task of each node is the information that the own lower floor that wants information transmitted and receive itself transmits up all will be reached upper layer node in the network.The information direction of transfer of whole network as shown in figure 17.Need to prove that each node only sends information to father node, and for each child node, father node is unique.

At data transfer phase, a node is a father node to its lower floor, is child node to its upper strata.Owing to adopted layering frequency division, control information narrow band transmission mechanism, concerning some nodes, received the information of lower level node and upper layer node is sent information and can regard two fully independently processes as.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 the data transfer phase receiving terminal control crash mode is uploaded process from information to its father node.Figure 19 shows certain node under the data transfer phase transmitting terminal control crash mode is uploaded process from information to its father node.Figure 20 shows the process that certain node under the data transfer phase receiving terminal control crash mode receives the information of its child node.Figure 21 shows the process that certain node under the data transfer phase transmitting terminal control crash mode receives the information of its child node.The particular content of data transfer phase will be explained in greater detail below.

Five, topological initial method

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

Table 1

Field name	Effect
		fun	Function field is fixed as 0
layer	Indication 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 is handled this frame and is comprised following step:

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

Add 1 if 2 values that receive the layer field of the TOPO_INIT frame that sends with Area Node are this node place numbers of plies, judge the information of issuing lower level node with node layer that received so.Be stored in the value in the parent_id field with in the node layer table this moment.

3, generate new topological delta frame, send to lower level node by correct frequency channels.The fun field composes 0, and the layer field is composed this node place number of plies and added 1, and the parent_id field is composed the numbering of this node oneself, and the 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 is waiting for that a segment protect sends after the time again, and purpose is to wait for that the topological delta frame that receives all upper layer node all sends after treatment again.

4, generate topological the generation and reply bag (TOPO_ACK), and return to upper layer node by correct frequency channels, upper layer node is tabulated according to wherein information updating child node and pseudo-child node.

If 5 receive the TOPO_INIT frame that the upper layer node of the higher priority of sending with Area Node (node serial number is less) is sent, so just will before father node be identified as pseudo-father node, the upper layer node that newly receives is identified as father node.And repeated for the 4th step, upgraded for the 3rd step.

6, receive one or more with regional TOPO_INIT frame prerequisite under, if the TOPO_INIT frame layer field value newly received greater than the number of plies of this node and with territory, this node same district, illustrate to have run into regional interior level problem this moment.Check the child node tabulation this moment, if this node directly abandons this frame in the child node tabulation; If this node is in child node tabulation, with the parent_id field store in " pseudo-father node is tabulated in the zone ".

7, receive one or more with regional TOPO_INIT frame prerequisite under, if the TOPO_INIT frame layer field value newly received less than the number of plies of this node and with territory, this node same district, illustrate to have run into regional interior level problem this moment.Check " pseudo-child node tabulation in the zone ",, so directly abandon this frame if in the table this node is arranged; If do not have in the table, in " pseudo-father node tabulation in the zone ", the number of plies information updating of this node is the layer field value with original information transfer in the father node tabulation, corresponding the parent_id field is stored in the father node tabulation, and repeated for the 4th step, upgraded for the 3rd step.

8, when receiving the TOPO_INIT frame of zones of different, illustrate that this node belongs to " interregional node ", stop immediately sending the TOPO_INIT frame to lower floor.This moment, the parent_id field with this frame was stored in " interregional pseudo-father node tabulation ".

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

Table 2

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

Upper layer node will be taken out the child_id field value after receiving this frame, and discern its child node for oneself.Following several situation might take place:

(1) frame of receiving is discerned it so and is child node for being oneself node number with zone and parent_id field, if this node serial number is present in other any node listings, deleted, and with the information storage of this node in child node is tabulated.

(2) frame of receiving is checked the child_layer field value for not being oneself node number with zone and parent_id field, divides three kinds of situation discussion: the first, equate with the network layer information of oneself as if this value, and the person of sending of frame is stored in tabulates with node layer.The second, if this value subtracts 1 with the network layer information of oneself and equates, the person of sending of frame is stored in " pseudo-child node tabulation ".The 3rd, if subtracting 1, this value and the network layer information of oneself do not wait, illustrate regional interior level problem has taken place.To be worth this moment and subtract 1 with own network layer information and compare, and if the former is less, illustrate that lower level node will have found the higher father node of priority, this lower level node is numbered and is stored in special " regional interior pseudo-child node is tabulated "; If the former is bigger, 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.

When the frame of (3) receiving is zones of different, illustrate that this node belongs to " interregional node ", this moment, the child_id field with this frame was stored in " interregional pseudo-child node tabulation ".

After carrying out topological initialization according to above-mentioned steps, each node has all write down local topology information: the 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 the communication range, pseudo-child node, interregional pseudo-father node, interregional pseudo-child node and quantity in the interior pseudo-father node in zone, the zone.

Six, data transmission method

At data transfer phase, a node is a father node to lower floor, is child node to the upper strata.Owing to adopted layering frequency division, control information narrow band transmission mechanism, concerning some nodes, received the information of lower level node and upper layer node is sent information and can regard two fully independently processes as.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 the data transfer phase receiving terminal control crash mode is uploaded process from information to its father node.Figure 19 shows certain node under the data transfer phase transmitting terminal control crash mode is uploaded process from information to its father node.Figure 20 shows the process that certain node under the data transfer phase receiving terminal control crash mode receives the information of its child node.Figure 21 shows the process that certain node under the data transfer phase transmitting terminal control crash mode receives the information of its child node.Introduce the scheme that child node sends data and father node reception data below respectively.

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.Below just analyze the situation of data transfer phase child node and the methods of disposal of this node under two kinds of control crash mode according to these three kinds of states.

State one: wait for transmission state.The node that is in this state has remaining data to transmit.This moment, the kind of the frame that node might be received had: 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	The 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	Purpose 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	Purpose 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	Purpose child node numbering
recv_seq	The frame number of confirming
		retrans_info	The relevant information that needs retransmission frame
NAV	Channel occupancy 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	Purpose father node numbering
		res_child_id	Source child node numbering
seq	Send sequence number
		NAV	Channel occupancy time indication information

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

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

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

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

1, generate the READY frame of oneself, send to lower level node, notify their communication beginnings.

If 2 have information to transmit, so just generate the RTS frame, when satisfying, the 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, the request access channel.

3, when node belongs to " interregional node " or do not have 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 the CTS frame can be done following work:

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

2 if father node is issued other child node, and the failure of expression channel contention is made as the father node state 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 the higher pseudo-child node of priority is sent, and must notify the child node of oneself to stop to transmit data.The node that receives the STOP frame can be done 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, is made as the father node state 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 the free time.

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

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

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

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

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

3, if node belongs to " interregional node ", and do not use " 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 message transmission), also will inquire about the priority of " interregional adjacent node " and whether be in idle condition when 2 condition satisfies so.(numbering is minimum) sends the RTS contention channel so immediately when the priority ratio of this node every other " interregional adjacent node " is all high; When the priority of this node when not being the highest, send the RTS contention channel when all being in idle condition immediately at " the interregional adjacent node " of high priority.

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

1, COMPETE frame cancellation.

2, similar with the virtual carrier monitoring mechanism of MACA, NAV value of node maintenance, the effect of this value is how long the transmission course in the current channel of indication 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, two kinds of frames of DATA, ACK carry special " NAV " field, when node is intercepted channel, the value in " NAV " field is handled the back preserve.But different with the virtual carrier monitoring in the MACA agreement is that " NAV " field will just can reach the idle effect constantly of predicted channel through the correction to propagation delay.The applied correction formula of this agreement can be expressed as:

{NAV}_{left} = \min ({NAV}_{rcv} - \frac{D_{rcv} + D_{des}}{V_{s}} {+ T}_{g})

State two: transmission state.The node that is in this state is to father node transmission data.At this moment the kind of the frame that 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 shown in.Wherein, DATA frame format and each field effect are as shown in table 9:

Table 9

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	Purpose father node numbering

Under the transmission state, the same section of two kinds of control crash mode comprises:

When child node when transmission state is received ACK, may be that father node is sent only.At this moment node can be checked the retransmission list of oneself.If this frame is through the frame that retransmits, remove the record in retransmission list so; If this frame is the normal ACK of frame according to the order of sequence, expression sends successfully so, prepares to send next time.More than all to add one to send window numerical value under two kinds of situations, expression can not have multiple again Frame under the situation about confirming.

If receive the 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.This moment, this node only needed pseudo-father node state is made as busy getting final product.If this frame, shows the transmission that high priority is arranged from father node and taken channel, must carve and stop transmit status.

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

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

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

The different piece of two kinds of control crash mode comprises:

When sending Frame (DATA), transmitting terminal control collision mode will be added " NAV " field in frame, and this field value is illustrated in the node that sends data and it seems, finishes the elapsed time that transfer of data also needs.The notion that this agreement regulation is finished transmission is that father node receives that the transmission that child node sends finishes (FINISH) frame.Therefore, the formula of the calculating NAV that takes of the agreement of present embodiment is as follows:

{NAV}_{data} = \frac{N_{left} (t_{p} + t_{g}) V_{s} + {3 D}_{est}}{V_{s}} + T_{g}

Wherein, NAV _DataIt is the NAV value that will be included in the Frame (DATA); N _LeftIt is the also remaining data frame number of transmitting terminal; t _pBe to send the used time of frame data; t _gBe the blanking time in the middle of transmission two frame data, assignment as the case may be; D _EstBe the distance between sending node and receiving node, can come out by the strength estimation of received signal; V _sBe the propagation velocity of sound in network institute working water acoustic environment; T _gIt is the guard time interval of introducing in order to prevent to calculate mistake.

It is worthy of note N _LeftValue to dynamically update according to the content of the ACK that receives.Carried the information that needs the frame that retransmits in the ACK frame, receiving node will need the number and the N of the frame that retransmits _LeftThe value addition is as new N _LeftValue.

State three: completion status.When the frame number that will send out when child node residue is O, enter completion status automatically.Enter finish attitude after, can return the preparation transmission state again if receive the RTS frame that lower level node is sent.When the data of all child nodes all transmit finish after, carry out dormancy to save the node energy at the reasonable time node.

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

1801) node obtains local detection data, and receives the data of lower level node, when these data accumulations to a certain degree the time, determine that this node will upload data as child node.

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

1803) described child node is intercepted channel, when 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 the RTS frame to father node, request transmission information.

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

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

1807) data of judging child node whole end of transmission whether is judged as not, enters step 1808, and being judged as is to enter step 1809).

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

1809) child node sends the FINISH frame, enters transmission completion status (being the completion status described in the preamble).

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

1811) its channel of uploading data of child node is set to busy state, gets back to step 1802), in this step, a kind of exception is arranged, if this child node receive be pseudo-father node send the STOP frame time, pseudo-father node state is made as idle condition.

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

1901) node obtains local detection data, and receives the data of lower level node, when these data accumulations to a certain degree the time, determine that this node will upload data as child node.

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

1903) described child node is intercepted channel, when not having the signal transmitting and NAV value in the channel and be 0, enters step 1904), in channel, there is signal (being Frame or control frame) to transmit, enter step 1910).In this step, child node also needs to upgrade the NAV value.

{NAV}_{left} =min ({NAV}_{rcv} - \frac{D_{rcv} + D_{des}}{V_{s}} + T_{g})

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

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

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

1907) data of judging child node whole end of transmission whether is judged as not, enters step 1908, and being judged as is to enter step 1909).

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

1909) child node sends the FINISH frame, enters transmission completion status (being the completion status described in the preamble).

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

1911) its channel of uploading data of child node is set to busy state, gets back to step 1902), in this step, a kind of exception is arranged, if this child node receive be pseudo-father node send the STOP frame time, pseudo-father node state is made as 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 present embodiment, have two kinds of patterns of receiving terminal control collision and transmitting terminal control collision, the concrete running of these two kinds of patterns is distinguished to some extent.Below 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.

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

Prepare under the accepting state, the same section of two kinds of control crash mode comprises:

Receive after the RTS, handle in two kinds of situation:

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

If 2 receive the RTS frame that pseudo-child node is sent in pseudo-child node or the zone, mean that then 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 simultaneously and keeps out of the way timer, enters halted state this moment.

Receive the 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 and gets final product.

2 if the DATA frame sent of pseudo-child node in pseudo-child node or the zone, and this situation is because under certain special state, father node fails to receive the RTS of pseudo-child node, therefore to send the STOP frame to child node and dodges.If this occurs, father node should be reissued the STOP frame to child node and dodge, and starts simultaneously and keeps out of the way timer, enters halted state.

The different piece of two kinds of control collision modes comprises:

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

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

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

The same section of two kinds of control collision modes comprises:

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

1 if the DATA frame that child node is sent, and this is normal situation, replys ACK according to sending sequence number accordingly and confirms.If some Frame has been missed in the DATA frame number generation saltus step that receives in the middle of the expression.This moment, node can deposit the sequence number of the frame lost in loss storage, and inserted retransmission information in the retrans_info of ACK frame field, and this ACK is sent to child node.The frame number that the 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 of taking out from the total_num field of RTS frame, and is stored in and loses in the register.

2 if the DATA frame that pseudo-child node is sent, this situation be that collision has taken place the data of sending with child node because the RTS of pseudo-child node sends laterly.Father node was failed to receive high priority RTS and child node was not sent the STOP frame this moment, caused data that the most serious collision has taken place.This moment, the child node send window exhausted owing to there is not correct ACK confirmation, suspend transmission, and the message transmission of pseudo-child node was carried out normally, so be bound to receive the Frame that pseudo-child node is sent after collision a period of time.Will send the STOP frame this moment to child node, enters halted state.

Receiving RTS is because the special case that improper time-delay causes is similar to second kind of situation receiving the DATA frame, sends the STOP frame, enters halted state.

The different piece of two kinds of control collision modes comprises:

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

2, father node is when sending acknowledgement frame (ACK), transmitting terminal control crash mode will be added " NAV " field (not needing to carry out this processing under the receiving terminal control crash mode) in frame, this field value is illustrated in the node that receives data and it seems, finishes the elapsed time that transfer of data also needs.The notion that this agreement regulation is finished transmission is that father node receives that the transmission that child node sends finishes (FINISH) frame.Therefore, the formula of the calculating NAV that takes in the agreement of present embodiment is as follows:

{NAV}_{ack} = {NAV}_{data} - \frac{D_{est} + T_{g}}{V_{s}}

Wherein, NAV _AckIt is the NAV value that will be included in the acknowledgement frame (ACK); NAV _DataIt is the NAV field value in data (DATA) frame sent of child node that father node receives; D _EstBe the distance between sending node and receiving node, can come out by the strength estimation of received signal; V _sBe the propagation velocity of sound in network institute working water acoustic environment; T _gIt is the guard time interval of introducing in order to prevent to calculate mistake.

State three: halted state.Halted state is to cause that purpose is to avoid the transfer of data of high priority, to avoid collision owing to received the RTS or the DATA frame of high priority.When father node received the 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 has only the 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 write down the reception number of pseudo-child node frame, for halted state releasing mechanism provides parameter.

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

There is a particular point to stress in halted state, keeps out of the way failure problem exactly.Receive the RTS of high priority when father node after, be bound to send the STOP frame and keep out of the way at once.But only preserve local topology information because the characteristics of this agreement are each nodes, can't learn whether the node of higher priority contention channel is arranged, the node that high priority promptly takes place possibly will be kept out of the way the data transmission of higher priority.So this agreement has adopted a kind of keeping out of the way to avoid insignificant from releasing mechanism and keep out of the way for a long time.Specific practice is: start at once after father node sends the STOP frame and keep out of the way timer, after the suitable time, timer initiation is judged process, the number of the pseudo-child node DATA frame that inspection receives, (not being made as 0 is because node had received CTS probably before keeping out of the way if less than a certain threshold value, and sent a small amount of DATA frame), then be judged as this priority node and also be forced to carry out keep out of the way.Keep out of the way failure this moment, finish halted state and send the COMPETE frame to allow child node contention channel again.Do the resource utilization that has improved network very effectively like this, improved throughput.

State four: completion status.In preparing accepting state, if there is not lower level node to send RTS, then father node enters completion status.

Below, introduce in conjunction with Figure 20 that certain node receives the main handling process that its lower level node is uploaded data under a kind of preferred receiving terminal control crash mode, comprise the following steps:

2001) certain node enters " preparation accepting state ".

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

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

2004) child node to lower floor sends the CTS frame, enters accepting state.

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

2006) send the ACK frame to child node.

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

2008) enter completion status.

Below, introduce in conjunction with Figure 21 that certain node receives the main handling process that its lower level node is uploaded data under a kind of preferred transmitting terminal control crash mode, comprise the following steps:

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

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

2104) child node to lower floor sends the CTS frame, enters accepting state.

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

2106) send the ACK frame to child node.

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

2108) enter completion status.

2109) sending a NAV value to lower level node is 0 ACK frame, gets back to step 2101).

Seven, about specific question

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

1) level problem in the zone

First kind of situation, as shown in figure 29.Efficient communication scope between the circle representation node, the communication band of topological all nodes of initial phase is identical.No. 10 nodes are aggregation node, and 7,8, No. 9 nodes are common sensor node.No. 7 nodes are initialized to 1 node layer within the communication range of No. 10 nodes.Though No. 8 node is very near from No. 7 nodes, outside No. 10 node communication scopes, be not initialised.After No. 7 node produces correct topological initialization information, send towards periphery, 8, No. 9 two node is both initialized to 2 node layers.8,9 liang of nodes can produce the topological initialization information of response equally, though yet two nodes are all within the other side's communication range, but according to the 7th point in the embodiment third part in the specification " definite method of pass-through mode and forwarding priority ", 8,9 liang of nodes can't change the information of place level after receiving the other side's topological initialization information, still think it oneself is 2 node layers, nodal scheme and the hierarchical information with the other side is stored in in the node layer tabulation (referring to the 2nd point in embodiment the 5th part " topological initial method ") simultaneously.

Second kind of situation, as shown in figure 30.Suppose that node 4 damages, at this moment cause to be in the topological initialization procedure that No. 9 nodes of the network layer second layer are initiated by 1,2 liang of node and 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 the 3rd floor by No. 1 node initializing also simultaneously.Can send topological initialization information to lower floor after No. 9 node is initialised, even this moment, No. 3 nodes received that this information can not be initialized to the 4th node layer yet, because will think that according to No. 3 nodes of regulation (referring to the 7th point in the embodiment third part " definite method of pass-through mode and forwarding priority ") of agreement forwarding priority the less upper layer node of level is a father node.Second kind of situation illustrated should the topology initialization mode still can operate as normal under the situation that some node damages, and the 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: this moment, No. 6 nodes sent topological initialization information to No. 2 nodes, and No. 2 nodes send topological initialization information to No. 6 nodes simultaneously.Stipulate according to agreement, No. 2 node is handled the topological initialization information of No. 6 nodes, but can not change own place level, this moment can be with the information storage of No. 6 nodes in " pseudo-father node be tabulated in the zone " (the 6th point in referring to embodiment the 5th part " topological initial method ").On the other hand, No. 6 node is handled the topological initialization information of No. 2 nodes, because No. 2 node place level is less, priority higher (referring to the 7th point in the embodiment third part " definite method of pass-through mode and forwarding priority "), so No. 2 nodes of No. 6 node identifications are father node, and change oneself place level into the 3rd layer, and send it back complex information and new topology generates information (referring to the 7th point in embodiment the 5th part " topological initial method ").No. 2 node receives No. 6 nodes to behind the return information of oneself, No. 6 nodes are deleted from " pseudo-father node tabulation in the zone ", and No. 6 nodes are stored in the child node tabulation (referring to the 9th point in embodiment the 5th part " topological initial method ").No. 5 nodes have received No. 6 equally and have given No. 2 topological return information, according to protocol contents No. 6 nodes are stored in " pseudo-child node tabulation in the zone " (referring to the 10th point in embodiment the 5th part " topological initial method ").The new topology of No. 6 node transmissions generates information and is ignored (referring to the 7th point in embodiment the 5th part " topological initial method " by No. 2 (referring to the 6th point in embodiment the 5th part " topological initial method ") and No. 5 nodes.So far, node 6 is as " the pseudo-child node in the zone " of No. 5 nodes, and node 5 is as " the pseudo-father node in the zone " of node 6, topology information initialization success.

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

No. 5 nodes among Figure 31 are not still explained as the reasonability of five node layers as the child node (four floor) of No. 6 nodes: though message transmission can be given aggregation node through hop count still less as four node layers, but as the path is faster has set up than 10,8,2

situation

10,7,1,3,4,5,6 paths in the hypothesis, illustrate that the former message transmission is all right, though latter's hop count is few, but it is relatively poor to transmit situation, so unnecessaryly pursue less hop count simply.

As follows to the solution that the conflict of the frequency band during level problem in the zone occurs:

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 information, No. 6 to No. 2 with frequency range 3 transmission information, the transmission of no significant information between No. 5 and No. 6.In the case, because frequency layered reuse mechanism role, the information transmission between two group nodes is not affected.In fact, so long as two adjacent sending nodes need not same frequency range send information just can not influence each other.Even and when two nodes of adjacent transmission information shared same frequency channels, as long as take control information narrow band transmission mechanism, do not have interactional problem (if needs can be explained in detail) yet.Present problem concentrates on adjacent two transmission nodes and transmits data and do not have control information narrow band transmission mechanism with identical frequency band just.We suppose that 5,6 liang of nodes of Figure 31 send data with identical frequency band, and this moment, No. 4 nodes produced for No. 5 return informations such as ACK when arriving No. 5 nodes to conflict probably 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 the embodiment third part " definite method of pass-through mode and forwarding priority ") of agreement, pseudo-byte point has higher transmission priority in the zone.In this case, No. 5 nodes are when receiving No. 6 nodes and issue No. 2 DATA or RTS frame, stop transmission immediately, send the FINTSH frame to the upper strata, to abdicate the taking of channel (referring to the related protocol content of the accepting state of record in the 6.1st in embodiment the 6th part " data transmission method ").

2) interregional fringe node problem

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

During the 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 " are analyzed below one by one.When " 4,6,5,2 ", 6 node layers that No. 3 nodes are zone 1 by No. 4 node initializing at first, father node is No. 4, and sends return information.After receiving No. 6 initialization information No. 3, because No. 4 ratios have higher priority (referring to the 6th point in the embodiment third part " definite method of pass-through mode and forwarding priority ") for No. 6, so regard as pseudo-father node with No. 6 No. 3.Behind the topological initialization information of receiving No. 5 and No. 2 for No. 3, according to agreement (referring to the 13rd point in the embodiment third part " definite method of pass-through mode and forwarding priority " (referring to the 8th point in embodiment the 5th part " topological initial method "), No. 3 with No. 5 with regard as " interregional pseudo-father node " No. 2.No. 3 return information also will all be received by 4 nodes.To think No. 3 for No. 4 for child node; To think No. 3 for No. 6 for pseudo-child node; Be " interregional pseudo-child node " (referring to the 11st point in embodiment the 5th part " topological initial method ") No. 3 with all thinking for No. 2 No. 5.

When " 5,2,4,6 ", No. 3 nodes will be initialized to the child node of No. 2 nodes in zone 2, and other and a last situation are similar.

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

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 made amendment or is equal to replacement, do not break away from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims

1. data transmission method that is used for the water sound sensor network system, described water sound sensor network system comprises aggregation node and sensor node, wherein, aggregation node is the 0th node layer, and the distance between the aggregation node is the 1st node layer in the efficient communication scope with interior sensor node; For each i node layer, remove upper layer node and with outside the node layer, with the distance of this i node layer be the i+1 node layer in the efficient communication scope with interior sensor node, wherein i is a positive integer, the 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 transmits control information to lower floor;

2. data transmission method according to claim 1 is characterized in that, when a node can be communicated by letter with a plurality of upper layer node simultaneously, one of them upper layer node is defined as father node, and lower level node is preferentially uploaded data by its father node.

3. data transmission method according to claim 2 is characterized in that, described step 3) adopts receiving terminal control crash mode to carry out data upload, comprises following substep:

31) the definite lower level node that need upload data;

32) upper layer node is sent the COMPETE frame;

4. data transmission method according to claim 3 is characterized in that, described step 3) also comprises following substep:

5. data transmission method according to claim 3, it is characterized in that, described step 33) in, when lower level node received that priority is higher than the control frame that node sent except that the STOP frame of its father node, its channel of uploading data of this lower level node was set to busy state.

6. data transmission method according to claim 2 is characterized in that, described step 3) adopts transmitting terminal control crash mode to carry out data upload, comprises following substep:

31) the definite lower level node that need upload data;

Described NAV value real-time update,

{NAV}_{left} = \min ({NAV}_{rcv} - \frac{D_{rcv} + D_{des}}{V_{s}} + T_{g})

7. data transmission method according to claim 6 is characterized in that, described step 3) also comprises following substep:

8. data transmission method according to claim 6, it is characterized in that, described step 32) in, when lower level node received that priority is higher than the control frame that node sent except that the STOP frame of its father node, its channel of uploading data of this lower level node was set to busy state.

9. according to each described data transmission method of claim 1～8, it is characterized in that the employed frequency band of described water sound sensor network system comprises first, second, third data message frequency band; If certain node level is N, satisfy N mod 3=0, then this node is 1 category node, satisfy N mod 3=1, then this node is 2 category nodes, satisfy N mod 3=2 then this node be 3 category nodes, the communication band between 1 category node and 2 category nodes, 2 category nodes and 3 category nodes, 3 category nodes and 1 category node adopts first, second, third data message frequency band respectively.

10. data transmission method according to claim 9 is characterized in that, the employed frequency band of described water sound sensor network system also comprises the control information arrowband, and the control frame between each node uses the control information arrowband to transmit.