CN102202393A - Method for locating WSN (Wireless Sensor Network) based on fast table lookup - Google Patents
Method for locating WSN (Wireless Sensor Network) based on fast table lookup Download PDFInfo
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- CN102202393A CN102202393A CN2011101192753A CN201110119275A CN102202393A CN 102202393 A CN102202393 A CN 102202393A CN 2011101192753 A CN2011101192753 A CN 2011101192753A CN 201110119275 A CN201110119275 A CN 201110119275A CN 102202393 A CN102202393 A CN 102202393A
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Abstract
The invention discloses a method for locating a WSN (Wireless Sensor Network) based on fast table lookup, comprising two steps of establishing and retrieving a hash table. The corresponding relationship between two-dimensional coordinates and a signal strength generation Key is stored in the hash table which is established in advance. The step of retrieving the hash table comprises the following steps of: retrieving the hash table through the signal strength generation Key; and performing conflict resolution if same Keys exist. On the basis of RSSI (Received Signal Strength Indication), the two-dimensional hash (Hash) table is introduced; and fast lookup and location are realized through the two-dimensional hash table by using a method that a theoretical model is combined with an empirical model. Location speed is improved while location precision is improved so as to realize two-dimensional location. Calculated quantity and signal transmission quantity in the location process can be greatly reduced.
Description
Technical field
The present invention relates to a kind of WSN localization method, belong to the wireless sense network field of locating technology based on quick computing technique.
Background technology
Wireless sense network has broad application prospects, but its energy problem restricts its extensive development always.Wireless sensing node adopts powered battery mostly, and electric weight is very limited; The sensing node number is many in addition, cost requirement is cheap, distributed areas are wide, is unpractical so replenish the energy by frequent replacing battery.Be subjected to the restriction of energy and node volume size, its computing capability is also very limited.Therefore the localization method of node must meet energy-conservation requirement just using value.
Wireless sensor network node self positioning method can have multiple sorting technique according to different angles, as absolute fix and relative positioning, centralized calculating and Distributed Calculation, based on the location of range finding and range-independence etc.The algorithm positioning accuracy of range-independence is relatively low, mainly contains based on range finding wireless signal time of advent (TOA), utilizes signal arrival time difference range finding (TDOA) and received signal angle (AOA) and the signal strength signal intensity that receives indicates (RSSI) to position according to distance and bearing between measured node based on the algorithm of range finding.The range computation amount of deciding based on range finding is big, the energy consumption height.
Locate widespread usage at the one dimension environment based on the RSSI that tables look-up now, range of application is very limited.And based on RSSI " fingerprint " though the location can be located at two-dimensional environment, as the destination node coordinate, this method is difficult to guarantee positioning accuracy apart from the nearest reference point coordinate of destination node for it.
Summary of the invention
Technical problem to be solved by this invention is the defective at background technology, and a kind of WSN localization method based on fast zoom table is provided, and realizes the quick location under low energy consumption and the low amount of calculation.
The present invention is for solving the problems of the technologies described above by the following technical solutions:
A kind of WSN localization method based on fast zoom table comprises the steps:
1-1 sets up two-dimensional coordinate according to the zone of wireless sense network, establishes origin of coordinates a respectively, coordinate transverse ends b is the base station;
1-2 is provided with the reference node of n known coordinate in two-dimensional coordinate, each reference node receives two signal of base station from a, b respectively, obtains two signal of base station intensity levels of a, b simultaneously respectively; Wherein n is a positive integer;
1-3, two signal of base station intensity levels that each reference node is obtained earlier respectively square after again addition generate Key;
1-4 is provided with the reference node of m known coordinate by constant spacing in two-dimensional coordinate, described reference node does not overlap with the reference node of step 1-2; Adopt the signal attenuation model to derive and obtain the relation of coordinate and node signal intensity level, draw in two-dimensional coordinate about the curve of node signal intensity level with changes in coordinates, m is a positive integer;
1-5 according to the curve that generates among the step 1-4, finds signal strength values by the reference node coordinate, execution in step 1-3;
1-6, the Key that all reference nodes are generated sorts, and makes that respectively pressing the Key ascending order arranges;
1-7 is stored in Key in the text successively by one-dimentional structure body array mode, sets up Hash table;
Step 2, by the location that the retrieval Hash table is realized unknown mobile node, concrete steps are as follows:
2-1 adopts two base stations of a, b to receive the signal of unknown mobile node in the wireless sense network by gateway, according to the relative a of this unknown mobile node, two signal of base station intensity levels of b, generates target Key according to the method for step 1-3;
2-2 compares the target Key of generation and the Key in the described Hash table of step 1-7 successively, until finding the value bigger than target Key, notes the number that identical Key occurs;
2-3, in the record of identical Key, two signal of base station intensity levels of comparison a, b are realized the conflict processing, find the coordinate figure of unknown mobile node, the location of realizing unknown mobile node.
Further, the WSN localization method based on fast zoom table of the present invention, the content of the body of one-dimentional structure described in step 1-4 array mode comprises Key, signal strength values, two-dimensional coordinate value.
The present invention adopts above technical scheme compared with prior art, has following technique effect:
This method can significantly reduce amount of calculation, the working transmission in the position fixing process.And can repeatedly table look-up at short notice and obtain coordinate, to improve positioning accuracy.Only need once comparison, can find the desired value coordinate, thereby reduce amount of calculation, the localization method of comparing based on range finding has reduced energy consumption, has shortened the time.
On the RSSI basis, introduce two-dimentional Hash (Hash) table, the method that adopts theoretical model to combine with empirical model is utilized two-dimentional Hash table, fast zoom table location.Improve locating speed simultaneously in the raising positioning accuracy, realized two-dimensional localization.
Description of drawings
Fig. 1 is that Key of the present invention generates schematic diagram.
Fig. 2 is an one-dimentional structure body array mode schematic diagram of the present invention.
Fig. 3 is a location of the present invention schematic diagram.
Fig. 4 is a flow chart of the present invention.
Embodiment
Below in conjunction with accompanying drawing technical scheme of the present invention is described in further detail:
The present invention includes and set up Hash table and retrieval Hash table two parts: stored the corresponding relation that two-dimensional coordinate and signal strength signal intensity generate Key in advance in the Hash table of setting up.The retrieval Hash table comprises that retrieval table is if having identical Key then the processing that conflicts by signal strength signal intensity generation Key.
One, sets up Hash table.
As shown in Figure 1, RSSI_a and RSSI_b are respectively two base station signal strength values of a, b of receiving and receive base-station node signal strength values RSSI_a and RSSI_b in the reference point (setting in advance) of known coordinate, and part is derived by the signal attenuation model and obtained coordinate and RSSI_a and RSSI_b between the reference point; With signal strength values RSSI_a and RSSI_b respectively square again addition generate Key.Then Key is sorted, make that respectively pressing the Key ascending order arranges, and be stored in successively in the text by one-dimentional structure body array mode that wherein, X, Y are node coordinate in mode shown in Figure 2.
As shown in Figure 3, the locating area that the present invention sets is indoor warehouse, and the warehouse length and width are D, set up two-dimensional coordinate system.(Sa is the fixed anchor nodes of known coordinate Sc) to black color dots among the figure, is considered as the base station; Base station cycle emission localizer beacon, destination node receives the back and sends to gateway according to the signal strength signal intensity that detects, and locatees continuously.Round dot among the figure be on movement locus at random or equally distributed reference point, triangulation point is the user node of unknown coordinates, this is an empirical model.Corresponding to step 1-2 to 1-3.
According to the wireless signal attenuation model, can obtain the situation of change of base station signal strength as logarithm-normal distribution model with customer location, along with the increase of destination node and base station distance, the continuous minimizing of signal strength signal intensity is a monotone variation.Therefore can find the corresponding relation of the signal strength signal intensity and the distance of base station and mobile node by the attenuation model of setting up, this is a theoretical model.Corresponding to step 1-4 to 1-5.
Can set up two-dimentional Hash table in conjunction with empirical model and theoretical model.
Two, retrieval Hash table.
As shown in Figure 4, at first, receive the signal of unknown mobile node about base station a, b, then with the signal strength values RSSI_a ' of signal a ' and signal b ' and RSSI_b ' respectively square again addition generate target Key.
Secondly, with the Key in the target Key comparison Hash table, up to finding the value bigger than target Key, note the number that identical Key occurs successively, N is the number of the identical Key that finds among the figure.
With signal strength values RSSI_a ', the RSSI_b ' of unknown mobile node respectively with the record of identical Key in RSSI_a and RSSI_b compare, find the identical Key of signal strength values, realize the conflict processing, thereby find the coordinate of unknown mobile node, the location of realizing unknown mobile node.
Only need once to compare by this method, can find the desired value coordinate, thereby reduced amount of calculation.
Claims (2)
1. the WSN localization method based on fast zoom table is characterized in that, comprises the steps:
Step 1 adopts empirical model and theoretical model to set up Hash table, and concrete steps are as follows:
1-1 sets up two-dimensional coordinate according to the zone of wireless sense network, establishes origin of coordinates a respectively, coordinate transverse ends b is the base station;
1-2 is provided with the reference node of n known coordinate in two-dimensional coordinate, each reference node receives two signal of base station from a, b respectively, obtains two signal of base station intensity levels of a, b simultaneously respectively; Wherein n is a positive integer;
1-3, two signal of base station intensity levels that each reference node is obtained earlier respectively square after again addition generate Key;
1-4 is provided with the reference node of m known coordinate by constant spacing in two-dimensional coordinate, described reference node does not overlap with the reference node of step 1-2; Adopt the signal attenuation model to derive and obtain the relation of coordinate and node signal intensity level, draw in two-dimensional coordinate about the curve of node signal intensity level with changes in coordinates, m is a positive integer;
1-5 according to the curve that generates among the step 1-4, finds signal strength values by the reference node coordinate, execution in step 1-3;
1-6, the Key that all reference nodes are generated sorts, and makes that respectively pressing the Key ascending order arranges;
1-7 is stored in Key in the text successively by one-dimentional structure body array mode, sets up Hash table;
Step 2, by the location that the retrieval Hash table is realized unknown mobile node, concrete steps are as follows:
2-1 adopts two base stations of a, b to receive the signal of unknown mobile node in the wireless sense network by gateway, according to the relative a of this unknown mobile node, two signal of base station intensity levels of b, generates target Key according to the method for step 1-3;
2-2 compares the target Key of generation and the Key in the described Hash table of step 1-7 successively, until finding the value bigger than target Key, notes the number that identical Key occurs;
2-3, in the record of identical Key, two signal of base station intensity levels of comparison a, b are realized the conflict processing, find the coordinate figure of unknown mobile node, the location of realizing unknown mobile node.
2. the WSN localization method based on fast zoom table according to claim 1 is characterized in that: the content of the body of one-dimentional structure described in step 1-7 array mode comprises Key, signal strength values, two-dimensional coordinate value.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103544305A (en) * | 2013-11-01 | 2014-01-29 | 上海斐讯数据通信技术有限公司 | Two-dimensional dynamic contact inquiry list inquiring method and system based on double-hash structure |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011008206A1 (en) * | 2009-07-15 | 2011-01-20 | Lockheed Martin Corporation | Method and apparatus for geographic positioning |
| CN102006663A (en) * | 2010-12-03 | 2011-04-06 | 北京工业大学 | Safe positioning method in wireless sensor network |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011008206A1 (en) * | 2009-07-15 | 2011-01-20 | Lockheed Martin Corporation | Method and apparatus for geographic positioning |
| CN102006663A (en) * | 2010-12-03 | 2011-04-06 | 北京工业大学 | Safe positioning method in wireless sensor network |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103544305A (en) * | 2013-11-01 | 2014-01-29 | 上海斐讯数据通信技术有限公司 | Two-dimensional dynamic contact inquiry list inquiring method and system based on double-hash structure |
| CN103544305B (en) * | 2013-11-01 | 2017-12-19 | 上海斐讯数据通信技术有限公司 | List query method and system are inquired about based on double hash data structure two dimension dynamic movement people |
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