CN109743690A - The broadcasting method based on direction and distance in vehicular ad hoc network towards urban road - Google Patents
The broadcasting method based on direction and distance in vehicular ad hoc network towards urban road Download PDFInfo
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Abstract
The invention discloses the flooding algorithms towards urban road in a kind of vehicular ad hoc network.Node in using vehicle as broadcast establishes vehicular ad hoc network, obtains the location information of node and carries out broadcast communication, each node is provided with neighbor information table；Source node starts peripherad node and sends broadcast packe, and the node for receiving broadcast packe sends broadcast packe to the node around itself again；Forward mode is divided into two kinds of forthright scene forward mode and crossing scene forward mode, and node is according to itself and upper hop node location state switching forward mode；Every kind of forward mode carries out the division of road area according to road direction, and node driving direction farthest to distance can be communicated in the road area of present node by, which selecting, is forwarded for the node far from road area direction where present node as next-hop forward node.The present invention can substantially reduce forward node number, effectively inhibition broadcast storm, reduce delay, adapt to the network topology of dynamic change in vehicular ad hoc network, while can also provide certain broadcast reliability.
Description
Technical field
The invention belongs to wireless communication technology fields, and in particular in a kind of vehicular ad hoc network towards urban road based on
The broadcasting method in direction and distance.
Background technique
Vehicular ad hoc network be a kind of multi-hop, non-stop layer, self-organizing cordless communication network, mainly by between vehicle and vehicle
Communication composition.Vehicular ad hoc network is the vehicle in certain wireless coverage, passes through the wireless communication module being respectively equipped with
Exchange and transmitting information and date etc., and the mobile network set up is connected automatically.It is mainly wide from inhibition in vehicular ad hoc network
Storm is broadcast, delay is reduced and improves the angle research broadcast technology of broadcast reliability.
By the broadcasting scheme in vehicular ad hoc network according to the difference of application scenarios, the broadcast towards urban road can be divided into
Scheme and two kinds of broadcasting scheme towards highway.In urban road, road and traffic condition are more complicated changeable, in mesh
In the preceding existing all kinds of flooding algorithms towards urban road, some does not account for road conditions different in urban road,
Some broadcast storm inhibitory effects are bad, the higher or reliability that is delayed is not high, and some algorithms are excessively complicated, implement
More difficulty or cost of implementation are higher, comprehensively consider and inhibit broadcast storm, reduce delay and provide certain broadcast reliability, mention
Method of the present invention is gone out.
Summary of the invention
The purpose of the invention is to provided in vehicular ad hoc network it is a kind of towards urban road based on direction and distance
Broadcasting method, can effectively inhibit broadcast storm, reduce delay, adapt to the network topology of dynamic change and provide certain
Reliability, be specifically exactly in vehicular ad hoc network towards urban road based on direction and distance broadcasting method (DDBB,
Direction and Distance Based Broadcasting algorithm)。
To achieve the goals above, the invention adopts the following technical scheme: the node in using vehicle as broadcast establishes vehicle
It is downloaded from networking, location information of the position location as node is obtained by the alignment sensor detection of vehicle itself, by vehicle
The wireless telecom equipment of installation carries out the broadcast communication between node, and each node is provided with neighbor information table, broadcast packe
Receive record sheet；Neighbor information table preserves neighborhood information entry, and broadcast packe reception record sheet is preserved broadcast packe and connect
Receipt purpose record.
Using any a certain node as source node, source node starts peripherad node and sends broadcast packe, receives broadcast
The node of grouping forwards broadcast packe to the node around itself again；
Each vehicle on road carries out node in the process of moving, in different road scene positions in different ways
Between broadcast packe forwarding, forwarding and broadcast communication during, source node according to itself site of road determine selection forwarding mould
Formula carries out the transmission of broadcast packe, relay node, that is, the node of non-source node, according to itself site of road and upper hop section
Point site of road determines that selection forward mode carries out the forwarding of broadcast packe；Upper hop node refers to that node received broadcast is grouped
The node in source.
Every kind of forward mode carries out the division of road area, road of the preferential selection in present node according to road direction
It is the node conduct far from road area direction where present node that and node driving direction farthest to distance can be communicated in region
Next-hop forward node, node constructs neighbor information table by the interaction forwarding communication of broadcast packe, secondly according to according to node
The location information of all neighbors is selected apart from farthest node as next-hop forward node in neighbor information table.
Described carries out the forwarding of the broadcast packe between node in different road scene positions in different ways specifically:
Different road scene positions are divided into forthright scene and crossing scene, and forward mode is divided into forthright scene forward mode and crossing scene
Forward mode, two kinds of forward modes are specifically respectively as follows:
(1) forthright scene forward mode
Any node j is as present node using in vehicular ad hoc network, then:
In the present invention, to number of track-lines and lane width, there is no limit here in order to illustrate situation, it is assumed that forthright scene is
Two-way 4 lane of standard, as shown in figure 3, using intersection point of the node j at road-center solid line as the center of circle, with from the one of the center of circle
Fixed directions of rays is angle augment direction as 0 ° of benchmark of angle counterclockwise, and the road area of forthright scene is divided range
For following four region E1、E2、F1、F2:
E1: (270 °, 360 °]；E2: (0 °, 90 °]
F1: (90 °, 180 °]；F2: (180 °, 270 °]；
First according to the position coordinates (x of q-th of neighbors in the neighbor information table of node jjq,yjq) and center location (xo,
yo) calculate the distance between q-th of neighbors and the center of circle djq, line angle value ω between q-th of neighbors and the center of circlejq,
Then according to line angle value ωjqJudge that neighbors belongs to four region E1、E2、F1、F2Which of region and as neighbour save
The road area of point, q=1,2,3 ... n, n indicates the sum of neighbors in the neighbor information table of node j, according to said method to institute
There is neighbors to carry out zone marker；
(2) crossing scene forward mode
Any node j is as present node using in vehicular ad hoc network, then:
There is no limit for number of track-lines and lane width of the present invention to crossing scene, in order to embody the generality of crossing scene,
In the crossing scene of hypothesis, any one branch can be not present, and T-shaped road junction, turning crossing etc. be formed, respectively such as Fig. 5-Fig. 7
Shown, what arrow direction indicated is the driving direction of node, by taking crossroad as an example；
Four corner vertex position m that known crossing road sorts along single clockwise/counterclockwise1、m2、m3And m4, corner
Vertex position m1、m2、m3And m4It is obtained by numerical map and the positioning system acquisition being equipped with, by line between corner vertex
m1m3The line m between corner vertex2m4Intersection point as the center of circle, i.e., with four corner vertex position m1、m2、m3And m4It constitutes
Two diagonal line intersection points of quadrangle are the center of circle using the fixed directions of rays from the center of circle as 0 ° of benchmark of angle, are counterclockwise
Angle augment direction, with the center of circle respectively to the line of solid line end between two-way lane on each road and corner vertex m1m3、
m2m4Line by crossing region division be eight regions, road direction is followed successively by A as benchmark where using 0 ° of angle1、A2、B1、
B2、C1、C2、D1And D2, by comparing the position coordinates (x of q-th of neighbors in the neighbor information table of node jjq,yjq) it is in position
It sets and eight region A1、A2、B1、B2、C1、C2、D1And D2Between relationship obtain neighbors belong to which of eight regions region
And the road area as neighbors, wherein eight regions merge while being divided into according to the same running region for being located at solid line two sides
Four road component regions.
Due in the present invention, it is assumed that crossing scene be the crossroad situation with versatility, T-shaped
The relatively conventional crossing scene in crossing, turning crossing and rotary island crossing etc. can equally be applicable in the present invention.
Node is in road scene position and is judged in the following way: being judged whether according to the position location of node
In the range that crossing central point is the center of circle, radius is 150m circle, if it is, node is in the road scene position of crossing scene
It sets, carries out crossing scene forward mode；Otherwise node is in the road scene position of forthright scene, carries out forthright scene and forwards mould
Formula.
Node driving direction is judged according to node-link region, is single after the division of road area of the present invention
Driving direction, the vehicle heading in node-link region are the driving direction of node.
Broadcast packe forwarding specifically:
(1) source node sends broadcast packe:
Any node i using in vehicular ad hoc network is as the source node for generating broadcast packe, then:
First source node i broadcast packe receive record sheet in add the received record of the broadcast packe, this be for
Source node i is uniformly processed, in the neighbor information table for then judging source node i when receiving the broadcast packe again
With the presence or absence of neighbors:
If it is not, then using 4 identical special addresses (254.255.255.255) as forward node address；
If so, further judging that source node i is in forthright scene or crossing scene:
If being in forthright scene, forthright scene forward mode is taken to select next-hop forward node；
If taking crossing scene forward mode to select next-hop forward node in the scene of crossing；
(2) any node j receives after broadcast packe processing forward in the following ways:
If after node j receives a broadcast packe from upper hop node h, successively judging whether to receive from node h for the first time
To broadcast packe, whether be to receive the broadcast packe and then to make alignment processing for the first time:
Or establish or update the corresponding entry of upper hop node h that the broadcast packe is sent in neighbor information table；
Or be forwarded by probability or according to the forward node address in broadcast packe head, before forwarding according to itself
The road scene position of road scene position and upper hop node h determines different positioned at forthright scene or crossing scene
Forward mode simultaneously selects next-hop forward node, the broadcast packe head that the address write-in of forward node is needed to send, and turns
Send out broadcast packe；
Or the broadcast packe was abandoned because having received the broadcast packe；
(3) entry of each neighbors k is provided with time-out time T in the neighbor information table of any node j1, in node j
During being in communication with each other with neighbors k any two node, neighbors in the neighbor information table of deletion of node j in the following ways
The entry of k, interior joint k are the neighbors of node j:
If neighbors k item corresponding time-out time T now in the neighbor information table of node j1Timing is arrived, then illustrates the time-out
Time T1The information of neighbors k was not refreshed in interior neighbor information table, illustrated neighbors k for a long time without broadcast packe
It sends, has not been the neighbours of node j, the entry of corresponding node k in the neighbor information table of node j is deleted.
(4) all nodes alternately and repeatedly execute step (1) to (3) in network, until all nodes do not need to forward again extensively
Broadcast grouping.
Forward mode is particularly divided into forthright and crossing scene forward mode by the present invention, is divided in each pattern by direction
Road area, using, as forward node, this algorithm can inhibit to broadcast apart from farthest node in the road area selected
Storm improves broadcast reliability, reduces time delay, the network topology of dynamic change suitable for urban road scene.
Each present node sends broadcast packe: by source node i address, broadcast packe sequence number, broadcast purpose
IP address, the address of present node j, the position coordinates of present node j, forward node address and present node j belonging positions shape
Broadcast packe head is written in state, then sends broadcast packe.When receiving broadcast packe, the broadcast packe received is being broadcasted
It receives in record sheet and establishes entry, and add the record of reception of the broadcast packe in the entry.
(2) specifically:
The processing forward in the following ways after any node j receives a broadcast packe from upper hop node h:
(2-1) first determines whether node j receives broadcast packe from node h for the first time:
If so, establishing the neighbor information entry of node h in the neighbor information table of node j, saved using node h as neighbours
Point, and by the location information (x of broadcast packe head interior joint hh,yh) it is stored in the entry, and it is super in the write-in of the corresponding position of the entry
When time T1, turn to (2-2)；
If it is not, then updating the location information (x of neighbor information table interior joint hh,yh) and resetting time-out time T1, turn again to
(2-2)；
(2-2) according in the broadcast packe that receives source node IP address and broadcast packe sequence number judge that node j's is wide
It broadcasts grouping and receives in record sheet whether have the received record of the broadcast packe:
If so, abandoning the broadcast packe, then (2-5) is turned to；
The received record of the broadcast packe is added if it is not, then receiving in record sheet in the broadcast packe of node j, is then sentenced
Whether 4 forward node addresses on the disconnected broadcast packe head received are entirely special address (254.255.255.255):
If so, node j forwards the broadcast packe with probability 0.5, turn to (2-3)；
If it is not, then judging the address of node j whether in the forward node address list on the broadcast packe head:
If so, node j needs to forward the broadcast packe, turn to (2-3)；
If it is not, then abandoning the broadcast packe (all data of the broadcast packe abandon), turn to (2-5)；
(2-3) node j is located at forthright scene or crossing according to the road scene position of itself and upper hop node h
In scene, selects different forward modes and selects next-hop forward node:
If upper hop node h is located at forthright scene, and node j itself is located at forthright scene, then forthright scene is taken to forward
Mode removes road area where upper hop node h, according to Fig. 7 in another road area of same node driving direction
Method choice next-hop forward node, turn to (2-4)；
If upper hop node h is located at forthright scene, and node j itself is located in the scene of crossing, then illustrates that node j needs
Next-hop forward node is selected on the different directions at crossing, takes crossing scene forward mode, removes road where upper hop node h
The region on road turns to (2-4) according to Fig. 8 method choice next-hop forward node on remaining three road areas；
If upper hop node h is located in the scene of crossing, does not have to the road scene position for judging node j itself, directly adopt
Cut-off road scene forward mode forwards section according to the method choice next-hop of Fig. 7 in the road area of node j driving direction
Point turns to (2-4)；
If above-mentioned upper hop node h is located in the scene of crossing, it is specifically divided into following two:
If upper hop node h is located in the scene of crossing, and if node j itself be located in the scene of crossing, illustrate that node j is
The next-hop forward node being located on the different directions of crossing being selected, node j does not need the different directions at crossing at this time
Upper selection next-hop forward node, then take forthright scene forward mode；
If upper hop node h is located in the scene of crossing, and if node j itself be located at forthright scene, illustrate that node j is following
It is forwarded on forthright, then equally takes forthright scene forward mode.
(2-4) node j by the source node address of broadcast packe, the sequence number of broadcast packe, broadcast packe destination IP
Location, the address of present node j, the position coordinates of present node j, next-hop forward node address and present node j position shape
Broadcast packe head to be forwarded is written in state, sends broadcast packe；
(2-5) terminates.
The node forwards broadcast packe with 0.5 probability specifically: node j generates one in 0-1 using random function
Equally distributed random number p directly abandons the broadcast packe if p > 0.5 in range；Otherwise node j forwards the broadcast packe.
The node calculates neighbors and the line angle in the center of circle calculates in the following ways:
The neighbors k of any node j and the line angle value in the center of circle can be determined according to the position coordinates of two nodes
ωk.The method for calculating angle is as follows: first looking at the position coordinates (x of neighbors k in the neighbor information table of node jk,yk), knot
Close the position coordinates (x in the center of circleo,yo), the line angle value ω of neighbors k and the center of circle are calculated by following formulak。
Wherein L is the slope of the line in neighbors k and the center of circle.
But due to only L being leaned on not can determine that ωkValue, therefore also need combine following formula uniquely determine ωkValue.
Y=yk-yo
If the value of L and Y is positive, ωk∈(0°,90°]；
If the value of L is negative, the value of Y is positive, then ωk∈(90°,180°]；
If the value of L is positive, the value of Y is negative, then ωk∈(180°,270°]；
If the value of L is negative, the value of Y is negative, then ωk∈(270°,360°]。
The line angle value ω in neighbors k and the center of circle can be accurately obtained by the above methodk。
The network requirement of the method for the present invention design are as follows:
Node in network all uses omnidirectional antenna mode；Node in network is on same plane, and each section
Point is equal；Node in network uses distributed structure；It is each to save when node in network is in mutual communication range
Point is all made of bidirectional communication link；Each node transmitting power and reception power in network is all the same, and transmitting message is covered
Range be radius be R circle；All nodes have been provided with numerical map, install positioning system, can obtain node in real time certainly
The geographical coordinate of each position in body and road scene knows that node itself is in forthright scene or crossing scene；All sections
Point is in urban road scene, and urban road scene includes forthright scene and crossing scene, and road can be one-way or bi-directional
Lane does not limit road width and number of track-lines, some road component road in the scene of crossing is allowed to be not present.
The broadcast packe includes source node IP address, broadcast packe sequence number, broadcast purpose IP address, present node IP
Address, the position coordinates of present node, the IP address of forward node, the location status of present node and data field.
The neighbor information table of the node include the IP address of present node, the IP address of neighbors, neighbors position
The time-out time of coordinate and neighbors.
According to the actual conditions of urban road, forward mode is divided into forthright scene forward mode and crossing scene forwards mould
Two kinds of formula, node automatically switches forward mode according to the location status of itself and upper hop node；In two kinds of forward modes all
Without considering number of track-lines, lane width and specific crossing situation, the division in region is carried out according to road direction, in each choosing
Select node as next-hop forward node in the direction region of taking-up；It is preferentially far from present node in node driving direction
The neighbors farthest apart from present node is selected in region, increases extra broadcast coverage area, so as to mitigate broadcast storm；
And real-time update neighbor information table during any two node is in communication with each other, in network all nodes using aforesaid way into
Row broadcast communication, until all nodes do not need to forward broadcast packe again.
The invention has the following beneficial effects:
(1) present invention can effectively inhibit broadcast storm.The present invention replaces according to forthright in urban road with crossing
Forward mode is divided into forthright scene forward mode and crossing scene forward mode, in each mode the road Jun Dui by existing characteristic
Road divides region by direction, and selects apart from farthest node in each direction region as next-hop forward node.By working as
Front nodal point determines next-hop forward node according to the information grasped, it is possible to reduce the number of nodes for participating in broadcast packe forwarding, from
And the number for repeating forwarding is reduced, forward node number is substantially reduced, to restrained effectively broadcast storm.
(2) average end-to-end time delay of the invention is lower.In the method for the present invention, present node can be jumped in range in one and be selected
The farthest neighbors of distance on different directions is selected as next-hop forward node, this meeting is so that present node and next-hop forwarding save
Wireless coverage overlapping region area between point is minimum, and the extra broadcast coverage area of next-hop node increases；Due to turning
Region where sending out node is different, and collision can also be reduced；And the node for participating in forwarding tails off, and broadcast packe can pass through less
Coverage whole network；These can all reduce average end-to-end time delay to a certain extent.
Detailed description of the invention
Fig. 1 is a kind of broadcast flow chart of the invention；
Fig. 2 is a kind of flow chart of forthright scene forward mode of the invention；
Fig. 3 is forthright schematic diagram of a scenario of the invention；
Fig. 4 is a kind of flow chart of crossing scene forward mode of the invention；
Fig. 5 is general crossing schematic diagram of a scenario of the invention；
Fig. 6 is T-shaped road junction schematic diagram of a scenario of the invention；
Fig. 7 is turning crossing schematic diagram of a scenario of the invention；
Fig. 8 is rotary island crossing schematic diagram of a scenario of the invention；
Fig. 9 is a kind of flow chart that source node of the invention sends broadcast packe；
Figure 10 is a kind of flow chart that arbitrary node of the invention receives and forwards broadcast packe；
Figure 11 is a kind of flow chart of deletion table interior joint entry after time-out time of the invention arrives；
Figure 12 is the neighbor information table example format schematic diagram in the present invention；
Figure 13 is that the broadcast packe in the present invention receives record sheet example format schematic diagram.
Specific embodiment
The present invention will be further described with reference to the accompanying drawings and detailed description.
As shown in Figure 1, a kind of broadcast flow chart of the invention specifically comprises the following steps:
Step 100, source node sends broadcast packe: node i is any source node for generating broadcast packe in network, first
Judge with the presence or absence of neighbors in the neighbor information table of source node i, if it is not, then with 4 identical special addresses
(254.255.255.255) is used as forward node address；If so, further judging that source node i is located at forthright scene or road
Mouth scene, takes forthright scene forward mode if being located at forthright scene, takes crossing scene to forward if being located at crossing scene
Mode；
Then by source node i address, broadcast packe sequence number, broadcast purpose IP address, present node i address, current
Broadcast packe head is written in position coordinates, forward node address and the present node j belonging positions state of node j, sends broadcast
Grouping；
Step 200, any node j is received and forwarding broadcast packe in network: when any node j is received from upper hop node h
To after a broadcast packe, successively judges whether to receive broadcast packe from node h for the first time, whether is to receive the broadcast for the first time
Grouping, then makes alignment processing；
Step 201, first determine whether node j receives broadcast packe from upper hop node h for the first time, if so, saving
The entry that node h is established in the neighbor information table of point j, by the position coordinates (x of node hh,yh) and broadcast coefficient be written to this
In entry, and the corresponding time-out time T of node h is written1, T1Initial value be 5s, turn to step 202；If it is not, then more new neighbor
Position coordinates (the x of information table interior joint hh,yh) and time-out time T1, turn to step 202；
Step 202, according in the broadcast packe received source node IP address and broadcast packe sequence number judge node j's
Whether the broadcast packe received record is had in broadcast receiving and transmitting record sheet, if so, showing is not to receive the broadcast point for the first time
Group then turns to step 400；The broadcast packe is received for the first time if it is not, being shown to be, then in the broadcast receiving and transmitting record sheet of node j
The received record of the broadcast packe is added, then judges whether 4 forward node addresses on the broadcast packe head received are complete
Portion is special address (254.255.255.255), if so, node j forwards the broadcast packe with probability 0.5；If it is not, then judging
The address of node j whether in the forward node address list on the broadcast packe head, if so, node j according to itself and it is upper
The location status of one hop node selects corresponding forward mode to forward the broadcast packe, turns to step 400；If it is not, then abandoning
The broadcast packe (all data of the broadcast packe abandon) turns to step 400；
Step 300, if upper hop node h item corresponding time-out time T now in the neighbor information table of node j1Timing is arrived,
Illustrate that the information of neighbor information table interior joint h in the time is not refreshed, neighbors h was sent out without broadcast packe for a long time
Come, be not the neighbours of node j, then deletes the entry of corresponding node h in the neighbor information table of node j；
Step 400, all nodes alternately and repeatedly execute step 100 to 300, until all nodes do not need to turn again in network
Send out broadcast packe.
As shown in Fig. 2, the method for forthright scene forward mode selection forward node of the invention, includes the following steps:
1. forthright schematic diagram of a scenario is as shown in figure 3, using intersection point of the node j at road-center solid line as the center of circle, level is straight
Road is using horizontal forthright direction as positive direction of the x-axis and as 0 ° of benchmark of angle, and vertical forthright is using vertical forthright as positive direction of the y-axis
It is counterclockwise angle augment direction and as 0 ° of benchmark of angle, it is following four that the road area of forthright scene, which is divided range,
Region E1、E2、F1、F2:
E1: (270 °, 360 °]；E2: (0 °, 90 °]
F1: (90 °, 180 °]；F2: (180 °, 270 °]；
2. according to the position coordinates (x of q-th of neighbors in node j neighbor information tablejq,yjq) and center location (xo,yo),
Calculate q-th of neighbors and center of circle distance djq, q-th of neighbors and the center of circle line angle value ωjq(q=1,2,
3……n)。
3. according to ωjq(q=1,2,3 ... n), judges which region all neighbors belong to, and to all neighbors
Carry out zone marker.
4. in E1Select the node farthest apart from the center of circle as forward node in region.If E1Region does not have neighbors, then exists
E2The node farthest apart from the center of circle is selected in region as forward node.If E2Also without neighbors in region, then it represents that E1With
E2Region does not have neighbors, can not select next-hop forward node, for the unification of broadcast packe format, with special address
(254.255.255.255) replaces forward node address.
5. in F1Select the node farthest apart from the center of circle as forward node in region.If F1Region does not have neighbors, then exists
F2The node farthest apart from the center of circle is selected in region as forward node.If F2Also without neighbors in region, then it represents that F1With
F2Region does not have neighbors, can not select next-hop forward node, for the unification of broadcast packe format, with special address
(254.255.255.255) replaces forward node address.
6. terminating.
As shown in figure 4, the method for scene forward mode selection forward node in crossing of the invention, includes the following steps:
1. crossing scene is as shown in Fig. 5, Fig. 6, Fig. 7 and Fig. 8, it is known that four corners of the crossing road along inverse time needle sort
Vertex position m1、m2、m3And m4, by line m between corner vertex1m3The line m between corner vertex2m4Intersection point as the center of circle,
It is counterclockwise angle augment direction, with the center of circle respectively to two-way lane on each road using positive direction of the x-axis as 0 ° of benchmark of angle
Between solid line end line and corner vertex line m1m3、m2m4It is eight region A by crossing region division1、A2、B1、B2、C1、
C2、D1And D2, by comparing the position coordinates (x of k-th of neighbors in the neighbor information table of node jjk,yjk) it is in position and eight
A region A1、A2、B1、B2、C1、C2、D1And D2Between relationship determine that neighbors belongs to which of eight regions region；
2. according to the position coordinates (x of q-th of neighbors in node j neighbor information tablejq,yjq) and center location (xo,yo),
Calculate q-th of neighbors and center of circle distance djq, q-th of neighbors and the center of circle line angle value ωjq(q=1,2,
3……n)。
3. according to ωjq(q=1,2,3 ... n) judge which region all neighbors belong to, and to all neighbors into
Row zone marker.
4. in A1The node farthest apart from the center of circle is selected in region as forward node.If A1Without neighbors in region, then
In A2The node farthest apart from the center of circle is selected in region as forward node.If A2Also without neighbors in region, then it represents that A1
And A2Region does not have neighbors, can not select next-hop forward node, for the unification of broadcast packe format, with special address
(254.255.255.255) replaces forward node address.
5. in B1The node farthest apart from the center of circle is selected in region as forward node.If B1Without neighbors in region, then
In B2The node farthest apart from the center of circle is selected in region as forward node.If B2Also without neighbors in region, then it represents that B1
And B2Region does not have neighbors, can not select next-hop forward node, for the unification of broadcast packe format, with special address
(254.255.255.255) replaces forward node address.
6. in C1The node farthest apart from the center of circle is selected in region as forward node.If C1Without neighbors in region, then
In C2The node farthest apart from the center of circle is selected in region as forward node.If C2Also without neighbors in region, then it represents that C1
And C2Region does not have neighbors, can not select next-hop forward node, for the unification of broadcast packe format, with special address
(254.255.255.255) replaces forward node address.
7. in D1The node farthest apart from the center of circle is selected in region as forward node.If D1Without neighbors in region, then
In D2The node farthest apart from the center of circle is selected in region as forward node.If D2Also without neighbors in region, then it represents that D1
And D2Region does not have neighbors, can not select next-hop forward node, for the unification of broadcast packe format, with special address
(254.255.255.255) replaces forward node address.
8. terminating.
As shown in figure 9, the method that source node of the invention sends broadcast packe, includes the following steps:
1. node i is any source node for generating broadcast packe in network, record is received in the broadcast packe of node i first
The received record of the broadcast packe is added in table, then judges node i with the presence or absence of neighbor information table, if it is not, then wide at this
4 identical special addresses (254.255.255.255) of write-in in the forwarding address list of grouping are broadcast, are turned to 2.；If so, into
One step judges that source node i is in forthright scene or crossing scene, if being in forthright scene, forthright scene is taken to forward mould
Formula selects next-hop forward node, turns to 2.；If taking crossing scene forward mode to select next-hop in the scene of crossing
2. forward node turns to；
2. by source node i address, broadcast packe sequence number, broadcast purpose IP address, present node i address, work as prosthomere
Broadcast packe head is written in position coordinates, forward node address and the present node j belonging positions state of point j, sends broadcast point
Group；
3. terminating.
As shown in Figure 10, arbitrary node of the invention receives the method with forwarding broadcast packe, includes the following steps:
1. node j receive upper hop neighbors h forwarding come broadcast packe after, it is first determined whether be for the first time from
Node h receives broadcast packe:
If so, establishing the neighbor information entry of node h in the neighbor information table of node j, and will be in broadcast packe head
Position coordinates (the x of node hh,yh) it is stored in the entry, and time-out time T is written in the corresponding position of the entry1, turn to 2.；
If it is not, then updating the position coordinates (x of neighbor information table interior joint hh,yh) and time-out time T1, turn to 2.；
2. judging that the broadcast packe of node j receives in record sheet whether have the received record of the broadcast packe:
If so, abandoning the broadcast packe, turn to 6.；
The received record of the broadcast packe is added if it is not, then receiving in record sheet in the broadcast packe of node j, is turned to
③；
3. judging whether 4 in broadcast packe forwarding address are special address entirely:
If being not all special address, judge node j whether in forward node address:
If not existing, illustrate that node j does not need to forward the broadcast packe, abandon the broadcast packe, turns to 6.；
If illustrating that node j needs to forward the broadcast packe, turning to 4.；
If being entirely special address, forward by probability, forwarded here with 0.5 probability, method particularly includes: node j is generated
One equally distributed random number α,
If α > 0.5, the broadcast packe is abandoned, is turned to 6.；
Otherwise, node j needs to forward the broadcast packe, turns to 4.；
4. node j according to the location status of itself and upper hop node h, that is, is located in forthright scene or crossing scene,
It determines different forward modes, and selects next-hop forward node:
If upper hop node h is located at forthright scene, itself is located at forthright scene, then takes forthright scene forward mode, remove
Upper hop node h direction region is gone to, next-hop forwarding is selected on another road area of same node driving direction
5. node turns to；
If upper hop node h is located at forthright scene, itself is located in the scene of crossing, illustrate node j need crossing not
Equidirectional upper selection next-hop forward node removes roadway area where upper hop node h so taking crossing scene forward mode
Domain selects next-hop forward node on remaining three road areas, turns to 5.；
If upper hop node h is located in the scene of crossing, if itself is located in the scene of crossing, illustrate that node j is to be selected
Be located at crossing different directions on next-hop forward node, at this time node j do not need on the different directions at crossing select under
One jumps forward node, but takes forthright scene forward mode；If itself is located at forthright scene, illustrate node j next straight
Road forwards, then equally takes forthright scene forward mode, so in conclusion if upper hop node h is located in the scene of crossing,
Do not have to the location status for judging itself then, directly takes forthright scene forward mode；Both of these case requires to travel in node j
Next-hop forward node is selected on the region of direction, is turned to 5.；
5. node j by the source node address of broadcast packe, the sequence number of broadcast packe, broadcast packe purpose IP address,
The address of present node j, the position coordinates of present node j, next-hop forward node address and present node j location status write
Enter broadcast packe head to be forwarded, sends broadcast packe；
6. terminating
As shown in figure 11, the method for deletion neighbor information table interior joint entry of the invention, includes the following steps:
If the time-out time T in the neighbor information table interior joint k entry of node j1Timing is arrived, then is believed the neighbours of node j
The corresponding entry of table interior joint h is ceased to delete；Terminate.
As shown in figure 12, it is the neighbor information table example format in the present invention, specifically includes:
1. IP address (node:j): indicating the IP address of present node j；
2. the information of the q neighbors of j, wherein n=1,2 ..., n, comprising:
IP address(node:jq): indicate the IP address of q-th of neighbors of node j；
(xjq,yjq): indicate the position coordinates of q-th of neighbors of node j, wherein xjqIndicate the horizontal seat of q-th of neighbors
Mark, yjqIndicate the ordinate of q-th of neighbors；
T1: indicate the time-out time of q-th of neighbors of node j, the time-out time of each neighbors in neighbor information table
Initial value is the same, is 5s.
If time-out time T1Timing is arrived, and the entry of neighbors k is not refreshed in the neighbor information table of node j, then it is assumed that should
Neighbors has not been the neighbors of present node j, and the entry of neighbors k is deleted from the neighbor information table of present node j
It removes.By time-out time T after recording and refresh every time1It is set as initial value.
As shown in figure 13, it is the broadcast receiving and transmitting record sheet example format in the present invention, specifically includes:
1. IP address (current node:j): the IP address of present node j；
2. the grouping situation for the broadcast packe Serial No. x that source node i issues, specifically:
IP address (source node:i): the IP address of source node i；
Packet sequence number x (from source node i): issue Serial No. x's from source node i
Broadcast packe；
T2: the time-out time of each broadcast packe receives in record sheet for time-out time to rear deletion broadcast packe
The entry of time-out, real-time update broadcast packe receive record sheet, T2Initial value is 30s.
Be received (Yes or No): it indicates whether to have received the broadcast packe, Yes expression has received, No table
Show and does not receive.
3. the grouping situation for the broadcast packe Serial No. y that source node m is issued, specifically:
IP address (source node:m): the IP address of source node m；
Packet sequence number y (from source node m): issue Serial No. y's from source node m
Broadcast packe；
T2: the time-out time of each broadcast packe receives in record sheet for time-out time to rear deletion broadcast packe
The entry of time-out, real-time update broadcast packe receive record sheet, T2Initial value is 30s.
Be received (Yes or No): it indicates whether to have received the broadcast packe, Yes expression has received, No table
Show and does not receive.
And so on.
Process according to the present embodiment can write out the program code of protocol method of the present invention, code compilation success
It can be applied in the broadcast of vehicular ad hoc network later.It improves, uses to preferably embody the performance of protocol method of the present invention
Network simulation simulation softward emulates protocol method of the present invention.
The method of the present invention is mainly analyzed from three performance indicators: (1) forward node ratio (Ratio
OfForwarding Nodes): in simulation process, the node number for participating in forwarding broadcast packe accounts for nodes sum
Ratio.(2) average end-to-end delay (Average End-to-end Delay): to this since source node issues broadcast packe
Broadcast packe receives the generated average value being delayed by whole destination nodes.(3) arrival rate (Reachability): all mesh
The node broadcast packe number that actually received broadcast packe number and whole nodes should receive ratio.
Where being best seen from the advantage of protocol method of the present invention, by method DDBB and DRIVE of the invention and
Tri- kinds of protocol methods of Flooding compare.Wherein, DRIVE protocol method is calculated according to oneself location information between neighbors
Then the angle value of neighbors and circle center line connecting out assigns neighbors different delay times further according to different angle values.
Flooding algorithm is special flooding algorithm based on probability, and the forwarding probability of each node is 1, that is to say, that each node
A jump range interior nodes can be all transmitted to after receiving broadcast packe for the first time.
It is emulated in the case of nodes number is different with source node packet sending speed.
(1) the forward node ratio of the DDBB method in the present invention is much smaller than DRIVE and Flooding agreement.
(2) the average end-to-end delay of the DDBB method in the present invention is significantly less than the flat of DRIVE and Flooding agreement
Equal end-to-end delay.
(3) the arrival rate stability of the DDBB method in the present invention is best compared to other 2 kinds.
According to analysis of simulation result, the present invention has advantage in forward node ratio and average end-to-end delay, can be compared with
Inhibit broadcast storm well, improve reliability, adapts to the urban road scene of node high-speed mobile.
It should be understood that this embodiment is only used to illustrate the invention but not to limit the scope of the invention.In addition, it should also be understood that,
After having read the content of the invention lectured, those skilled in the art can make various modifications or changes to the present invention, these etc.
Valence form is also fallen within the scope of the appended claims of the present application.
Claims (7)
1. towards the flooding algorithm of urban road in a kind of vehicular ad hoc network, it is characterised in that: the section in using vehicle as broadcast
Point establishes vehicular ad hoc network, obtains location information of the position location as node by the alignment sensor detection of vehicle itself,
The broadcast communication between node is carried out by the wireless telecom equipment installed on vehicle, each node is provided with neighbor information
Table；Source node starts peripherad node and sends broadcast packe, and the node for receiving broadcast packe turns to the node around itself again
Send out broadcast packe；Each vehicle on road in the process of moving, carries out in different ways in different road scene positions
Broadcast packe forwarding between node, during forwarding and broadcast communication, source node determines that selection turns according to itself site of road
Hair mode carries out the transmission of broadcast packe, and relay node determines selection according to itself site of road and upper hop node-link position
The forwarding of forward mode progress broadcast packe；Every kind of forward mode carries out the division of road area according to road direction, according to
In nodes neighbors information table the location information of all neighbors select node farthest apart from present node in running region as
Next-hop forward node, running region are region of the node driving direction far from the road area where present node.
2. the flooding algorithm towards urban road in a kind of vehicular ad hoc network according to claim 1, it is characterised in that: institute
That states carries out the broadcast packe forwarding between node in different road scene positions in different ways specifically: different road fields
Scape is divided into forthright scene and crossing scene, and forward mode is divided into forthright scene forward mode and crossing scene forward mode, and two kinds
Forward mode is specifically respectively as follows:
(1) forthright scene forward mode
Any node j is as present node using in vehicular ad hoc network, then: being with intersection point of the node j at road-center solid line
The center of circle is counterclockwise angle augment direction, by forthright field using the fixed directions of rays from the center of circle as 0 ° of benchmark of angle
It is following four region E that the road area of scape, which divides range,1、E2、F1、F2:
E1: (270 °, 360 °]；E2: (0 °, 90 °]
F1: (90 °, 180 °]；F2: (180 °, 270 °]；
First according to the position coordinates (x of q-th of neighbors in the neighbor information table of node jjq,yjq) and center location (xo,yo) meter
Calculate the distance between q-th of neighbors and the center of circle djq, line angle value ω between q-th of neighbors and the center of circlejq, then
According to line angle value ωjqJudge that neighbors belongs to four region E1、E2、F1、F2Which of region and as neighbors
Road area, q=1,2,3 ... n, n indicate the sum of neighbors in the neighbor information table of node j, then to all neighbors
Carry out zone marker；
(2) crossing scene forward mode
Any node j is as present node using in vehicular ad hoc network, then: known crossing road is along single clockwise/counterclockwise
Four corner vertex position m of sequence1、m2、m3And m4, by line m between corner vertex1m3The line m between corner vertex2m4
Intersection point as the center of circle, be counterclockwise angle increase side to be used as 0 ° of benchmark of angle from a fixed directions of rays in the center of circle
To with the center of circle respectively to solid line end between two-way lane on each road and corner vertex position m1m3、m2m4Line by road
Mouth region domain is divided into eight region A1、A2、B1、B2、C1、C2、D1And D2, adjacent by comparing q-th in the neighbor information table of node j
Position coordinates (the x of nodejq,yjq) it is in position and eight region A1、A2、B1、B2、C1、C2、D1And D2Between relationship obtain adjacent section
Point belongs to which of eight regions region and the road area as neighbors.
3. the flooding algorithm towards urban road in a kind of vehicular ad hoc network according to claim 2, it is characterised in that: section
Point is judged in the following way in road scene position: being judged whether according to the position location of node in crossing central point
It is, if it is, node is in the road scene position of crossing scene, to carry out crossing in the range of 150m circle for the center of circle, radius
Scene forward mode；Otherwise node is in the road scene position of forthright scene, carries out forthright scene forward mode.
4. the flooding algorithm towards urban road in a kind of vehicular ad hoc network according to claim 1, it is characterised in that: wide
Broadcast packets forwarding specifically:
(1) source node sends broadcast packe:
Any node i using in vehicular ad hoc network is as the source node for generating broadcast packe, then: first in the broadcast of source node i
Grouping receives in record sheet and adds the received record of the broadcast packe, then judge in the neighbor information table of source node i whether
There are neighbors:
If it is not, then using 4 identical special addresses (254.255.255.255) as forward node address；
If so, further judging that source node i is in forthright scene or crossing scene:
If being in forthright scene, forthright scene forward mode is taken to select next-hop forward node；
If taking crossing scene forward mode to select next-hop forward node in the scene of crossing；
(2) any node j receives after broadcast packe processing forward in the following ways:
If after node j receives a broadcast packe from upper hop node h, successively judging whether to receive extensively from node h for the first time
It broadcasts grouping, whether be to receive the broadcast packe for the first time, then make alignment processing:
Or establish or update the corresponding entry of upper hop node h that the broadcast packe is sent in neighbor information table；
Or be forwarded by probability or according to the forward node address in broadcast packe head, before forwarding according to itself road
The road scene position of scene location and upper hop node h is located at forthright scene or crossing scene determines different forwardings
Mode simultaneously selects next-hop forward node, and broadcast packe head is written in forward node address, then forwards broadcast packe；
Or the broadcast packe was abandoned because having received the broadcast packe；
(3) entry of each neighbors k is provided with time-out time T in the neighbor information table of any node j1, in node j and neighbour
During node k any two node is in communication with each other, neighbors k in the neighbor information table of deletion of node j in the following ways
Entry, interior joint k are the neighbors of node j:
If neighbors k item corresponding time-out time T now in the neighbor information table of node j1Timing is arrived, then is believed the neighbours of node j
The entry for ceasing corresponding node k in table is deleted.
5. the flooding algorithm towards urban road in a kind of vehicular ad hoc network according to claim 4, it is characterised in that: every
A present node sends broadcast packe: by source node i address, broadcast packe sequence number, broadcasting purpose IP address, current
The address of node j, the position coordinates of present node j, forward node address and the write-in broadcast point of present node j belonging positions state
Group head, then sends broadcast packe.
6. the flooding algorithm towards urban road in a kind of vehicular ad hoc network according to claim 4, it is characterised in that: institute
State (2) specifically:
The processing forward in the following ways after any node j receives a broadcast packe from upper hop node h:
(2-1) first determines whether node j receives broadcast packe from node h for the first time:
If so, establish the neighbor information entry of node h in the neighbor information table of node j, and by broadcast packe head interior joint h
Location information (xh,yh) it is stored in the entry, and time-out time T is written in the corresponding position of the entry1, turn to (2-2)；
If it is not, then updating the location information (x of neighbor information table interior joint hh,yh) and resetting time-out time T1, turn again to (2-2)；
(2-2) according in the broadcast packe that receives source node IP address and broadcast packe sequence number judge that the broadcast of node j divides
Group receives in record sheet whether have the received record of the broadcast packe:
If so, abandoning the broadcast packe, then (2-5) is turned to；
The received record of the broadcast packe is added if it is not, then receiving in record sheet in the broadcast packe of node j, then judgement is received
Whether 4 forward node addresses on the broadcast packe head arrived are entirely special address (254.255.255.255):
If so, node j forwards the broadcast packe with probability 0.5, turn to (2-3)；
If it is not, then judging the address of node j whether in the forward node address list on the broadcast packe head:
If so, node j needs to forward the broadcast packe, turn to (2-3)；
If it is not, then abandoning the broadcast packe, turn to (2-5)；
(2-3) node j is located at forthright scene or crossing scene according to the road scene position of itself and upper hop node h
It is interior, it selects different forward modes and selects next-hop forward node:
If upper hop node h is located at forthright scene, and node j itself is located at forthright scene, then takes forthright scene forward mode,
Road area where removing upper hop node h, selects next jump in another road area of same node driving direction
Node is sent out, is turned to (2-4)；
If upper hop node h is located at forthright scene, and node j itself is located in the scene of crossing, then crossing scene is taken to forward mould
Formula, road component region where removing upper hop node h, selects next-hop forward node on remaining road component region,
It turns to (2-4)；
If upper hop node h is located in the scene of crossing, do not have to the road scene position for judging node j itself, directly takes straight
Road scene forward mode selects next-hop forward node in the road area of node j driving direction, turns to (2-4)；
(2-4) node j by the source node address of broadcast packe, the sequence number of broadcast packe, broadcast packe purpose IP address, when
The location status write-in of the address of front nodal point j, the position coordinates of present node j, next-hop forward node address and present node j
Broadcast packe head to be forwarded sends broadcast packe；
(2-5) terminates.
7. the flooding algorithm towards urban road in a kind of vehicular ad hoc network according to claim 4 or 6, feature exist
In: the node forwards broadcast packe with 0.5 probability specifically: node j generates one within the scope of 0-1 using random function
Equally distributed random number p directly abandons the broadcast packe if p > 0.5；Otherwise node j forwards the broadcast packe.
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