CN105872977A - Improved LANDMARAC locating algorithm for wireless sensor network - Google Patents

Abstract

The invention provides an improved LANDMARAC locating algorithm for a wireless sensor network and belongs to the technical field of wireless communication. The improved LANDMARAC locating algorithm is applicable to locating of nodes in the wireless sensor network; the improved LANDMARAC locating algorithm based on the node signal strength is disclosed to solve the problem that the nodes in the wireless sensor network cannot be precisely located with relatively low power consumption and cost. With the adoption of the method, balance can be realized between precise location of the nodes in the wireless sensor network and relatively low deployment and operation cost. The algorithm comprises steps as follows: deployment of the wireless sensor network, broadcasting of anchor nodes, receiving of the nodes and recording of the signal strength, selection of the nearest neighbor nodes from the nodes and calculation of node positions with a centroid algorithm. The algorithm is simple in calculation and high in location precision, and needs no additional equipment, thereby being applicable to the wireless sensor network with limited resources at low cost.

Description

A kind of improvement LANDMRAC location algorithm for wireless sensor network

Technical field

The invention belongs to the technical field of radio communication, it is proposed that a kind of improvement based on node signal strength LANDMRAC location algorithm, it is adaptable to the node locating of wireless sensor network.

Background technology

Wireless sensor network node location relates to calculate and the complementary problem of science numerous areas, simultaneously Also closely bound up with various engineering system.Great majority are applied, it is not known that sensing station and perception Data are nonsensical.Sensor node must clear and definite self-position could describe in detail " where or Region there occurs particular event ", it is achieved location and the tracking to external object.On the other hand, sensor joint is understood Dot position information can also improve router efficiency, provides NameSpace for network, reports covering of network to arrangement person Lid quality, it is achieved the load balancing of network and the self-configuring of network topology.

For the position of node, can be by artificial arrangement after, record detailed geographical coordinate and carry out mark sensor The position of node.But record can expend substantial amounts of manpower and materials, and the environment of actual arrangement may be unsuitable for people Enter, therefore, the mode of this record node location is not suitable for this system.For sensor node, GPS is installed Locating module can also obtain the position of node.But due to cost, the restriction of node power consumption, it is impossible to will be every Individual node is all equipped with GPS module.A part of node can be equipped with GPS module, these nodes become anchor joint Point, is again beaconing nodes.Other nodes, by the data interaction between anchor node, utilize specific algorithm, Realize the location of self.

Location measurement technology includes: wireless time differential technique, wireless harmony signal measurement technique, signal intensity Measurement technology, wireless communications technology etc..

Mainly including location based on RSSI based on the alignment system measured, location based on TDOA, TOA determines Position, location based on TDOA, location based on AOA.

Measurement technology based on RSSI (RECEIVED SIGNAL STRENGTH INDICATOR): i.e. known node Transmitting power, receiving node measure receive power, calculate propagation loss, use the signal of theory or experience Propagation loss is converted into distance by propagation model.This technology mainly uses RF signal. because sensor node itself has There is wireless communication ability, be therefore the many such as the ranging technology of a kind of low-power consumption, low cost, RADAR, SPOTON Project employs this technology.Its main source of error is building of the signal propagation model that caused of environmental effect Mould complexity, reflection, multipath transmisstion, non line of sight (NON-LINE-OF-SIGHT, NLOS), antenna gain etc. Problem all can produce dramatically different propagation loss under distance same case.

Measurement technology based on TDOA (TIME DIFFERENCE ON ARRIVAL).TDOA ranging technology is by extensively General apply in WSN targeting scheme.It is usually and ultrasonic transmitter-receiver and RF transceiver are installed on node.Survey Away from time, at transmitting terminal, two kinds of transceivers launch signal simultaneously, utilize sound wave and electromagnetic wave to propagate speed in atmosphere The greatest differences of degree, in the receiving terminal difference by two kinds of unlike signal times of advent of record, passes based on known signal Broadcast speed, directly the time is converted into distance.The range accuracy of this technology relatively RSSI is high, can reach Centimeter Level, But it is limited to the ultrasonic propagation distance finite sum NLOS problem propagation effect to ultrasonic signal.

Ranging technology based on AOA (ANGLE OF ARRIVAL).This is that a kind of estimation neighbor node sends signal The technology in direction, can be implemented in combination in by aerial array or multiple receptor, in addition to location, moreover it is possible to provider To information, in the project such as THE CRICKET COMPASS of MIT, just propose location algorithm based on AOA. AOA technology is also affected by the external environment, as noise, NLOS problem etc. all can produce Different Effects to measurement result. Meanwhile, AOA needs additional hardware, possibly cannot meet sensor node to hardware size and the requirement of power consumption.

Ranging technology based on TOA (TIME OF ARRIVAL).This technology is by measuring signal propagation time Measure distance, it is therefore desirable between node, precise time synchronizes.The alignment system using TOA technology most basic is GPS.GPS system needs costliness, the electronic equipment of high energy consumption carrys out precise synchronization satellite clock.Due to WSN node Hardware size, price and power consumption limit, the targeting scheme of actual application TOA technology is less, but ultra-wide in the recent period The development of band (ULTRA-WIDEBAND, UWB) communication technology and the application in wireless sensor network, Make to utilize TOA location to be provided with wide prospect.

For background above information, study a kind of node locating algorithm being applicable to wireless sensor network and there is weight Want meaning.

Summary of the invention

Owing to rfid system and wireless sensor network are closely similar, inspired by LANDMARC algorithm, carried Go out the LANDMARC algorithm of a kind of improvement being applicable to wireless sensor network node location.Position with RFID System is compared, and the anchor node in wireless sensor network positioning system is equivalent to the reference label in rfid system； Node to be positioned in wireless sensor network is equivalent to the band location label in rfid system.The district that both are maximum Not being, in rfid system, the data of label need read write line to read, and cannot be carried out data interaction between label. And between the node in sensor network, can directly carry out data interaction, set without a special read-write The standby transmitting-receiving carrying out data.

Present invention solves the technical problem that: cannot realize for wireless sensor network with relatively low power consumption and cost Realizing being accurately positioned of node, the present invention proposes a kind of improvement LANDMRAC based on node signal strength location Algorithm.Use the method can wireless sensor network node be accurately positioned and relatively small configuration and operating cost it Between obtain balance.

Technical scheme: the wireless sensor network node with node locating function divides into anchor node With non-anchor node；Based on the signal power of anchor node, accurate according to node arest neighbors anchor node to be positioned Positional information calculation goes out the position of node to be positioned；Step is as follows:

(1) wireless sensor network being made up of some anchor nodes and ordinary node is disposed.

(2) anchor node positions and does the whole network node broadcasts, and non-anchor node receives and the transmitting power of record anchor node.

(3) node basis signal power to be positioned selects some arest neighbors anchor nodes.

(4) node to be positioned calculates self coordinate according to centroid algorithm and arest neighbors anchor node coordinate.

Beneficial effects of the present invention: this algorithm calculates simple, positioning precision height, it is not necessary to extras, therefore fits For low cost, the wireless sensor network of resource-constrained.

Detailed description of the invention

Below in conjunction with technical scheme, further illustrate the detailed description of the invention of the present invention.

A kind of improvement LANDMRAC location algorithm for wireless sensor network, with the signal power of anchor node be Basis, calculates the position of node according to the precise position information of node arest neighbors anchor node to be positioned.The present invention The wireless sensor network node with node locating function proposed divides into anchor node and non-anchor node.Wherein, Anchor node has perception, radio communication and accurate positioning function, can directly obtain the positional information of node self； But compared with non-anchor node, this category node is relatively costly, energy consumption is bigger.Non-anchor node only has regular node Perceptive function and basic short-distance wireless communication ability.

If system has the anchor node of m known location, n sensor node to be positioned；Step is as follows:

(1) anchor node and n the sensor node to be positioned of m known location are deployed into monitoring region, It is made into wireless network by Zigbee network protocol groups.

(2) m anchor node is to one group of signal of the whole network node broadcasts, and the transmitting power recording its broadcast singal is:

(3) n node to be positioned receives the signal from anchor node, and records received signal strength and be:

Wherein, S_ijRepresent the signal intensity of anchor node i that node j receives, then node j and anchor node i it Between Euclidean distance be:

(4) for each node undetermined, (Euclidean distance closest with it is selected according to the signal power received Minimum) K anchor node (arest neighbors anchor node).

(5) obtaining the coordinate of node to be positioned according to centroid algorithm and arest neighbors anchor node coordinate is:

$(x_j,y_j)=\underset{i=1}{\overset{K}{\Σ}}{w}_{ij}(x_i,y_i)$

Wherein, w_ijRepresent i-th anchor node node to be positioned to jth weight (i=1,2,3 ..., K<m；J=1,2,3 ..., n).Can be obtained by empirical equation:

$w_{ij}=\frac{1/E_{ij}^2}{\underset{i=1}{\overset{K}{\&Sigma;}}(1/E_{ij}^2)}$

By the actual coordinate of node to be positioned and the comparison of the coordinate of node to be positioned that obtains by above method, The error amount between them can be calculatedWherein (x_o,y_o) represent is joint to be positioned The real coordinate position of point；(x is y) by the calculated node coordinate to be positioned of algorithm above.This error amount Size be also to weigh the most important index that whether prepares of location algorithm.

Claims (1)

1. the improvement LANDMRAC location algorithm for wireless sensor network, it is characterised in that set in system There is the anchor node of m known location, n sensor node to be positioned；

Step is as follows:

(1) anchor node and n the sensor node to be positioned of m known location are deployed into monitoring region, It is made into wireless network by Zigbee network protocol groups；

(2) m anchor node is to one group of signal of the whole network node broadcasts, and the transmitting power recording its broadcast singal is:

(3) n node to be positioned receives the signal from anchor node, and records received signal strength and be:

Wherein, S_ijThe signal intensity of the anchor node i that expression node j receives, then node j and anchor node i Between Euclidean distance be:

(4) for each sensor node to be positioned, select with its distance according to the signal power that receives Closely, K the anchor node that i.e. Euclidean distance is minimum, K anchor node is arest neighbors anchor node；

(5) obtaining the coordinate of node to be positioned according to centroid algorithm and arest neighbors anchor node coordinate is:

$(x_j,y_j)=\underset{i=1}{\overset{K}{\&Sigma;}}{w}_{ij}(x_i,x_i)$

Wherein, w_ijRepresent i-th anchor node node to be positioned to jth weight (i=1,2,3 ..., K<m；J=1,2,3 ..., n)；Obtained by following formula:

$w_{ij}=\frac{1/E_{ij}^2}{\underset{i=1}{\overset{K}{\&Sigma;}}(1/E_{ij}^2)};$

Compared by the actual coordinate of node to be positioned and the coordinate of calculated node to be positioned, draw two The error amount of personWherein (x_o,y_o) represent is the actual coordinate of node to be positioned Position；(x is y) by the calculated node coordinate to be positioned of algorithm above.