Directional Antenna Intelligent Coverage Method Based on Traversal Optimization Algorithm

Jialuan He,Ζirui Xing,Rong Hu,Jing Qiu,Shen Su,Yuhan Chai and Yue Wu

Abstract: Wireless broadband communication is widely used in maneuver command communications systems in many fields,such as military operations,counter-terrorism and disaster relief.How to reasonably formulate the directional antenna coverage strategy according to the mobile terminal dynamic distribution and guide the directional antenna dynamic coverage becomes a practical research topic.In many applications,a temporary wireless boardband base station is required to support wireless signal communications between many terminals from nearby vehicles and staffs.It is therefore important to efficiently set directional antenna while ensuring large enough coverage over dynamically distributed terminals.The wireless broadband base station mostly uses two rotatable conical-polarized directional antennas with a coverage angle of 80 degrees.In this paper,we study this directional antenna coverage problem and propose a new solution by using three-dimensional coordinate transformation,provides wireless signal coverage schemes for point-to-point and point-to-region,determined the required horizontal rotation angle and pitch rotation angle of the directional antenna intelligent coverage,which lays the foundation for the performance of the wireless broadband communication in the maneuver command communication system.

Keywords: Wireless broadband communication,directional antenna intelligent coverage,three-dimensional coordinate transformation.

1 Introduction

With the development of wireless sensor networks [Wang,Gu and Yan (2018);Wang,Gu and Zhou (2017);Wang,Gu,Ma et al.(2017);Wang,Ju,Gao et al.(2018)],attacks can be effectively reduced by considering security [Yu,Tian,Qiu et al.(2018);Wang,Tian,Zhang et al.(2018);Tian,Cui,An et al.(2018);Tan,Gao,Shi et al.(2018)] and trustiness [Chen,Tian,Cui et al.(2018)] in wireless sensor networks.Wireless broadband communication is an important basis for the rapid and flexible construction of a communications network and the implementation of command tasks for maneuver command communications systems.It is widely used in many scenarios where no civilian mobile communication service facilities are available,for example,military operations,counter-terrorism,and disaster relief,etc.The wireless broadband communication base stations need to be temporarily erected through maneuver vehicles to vehiclery out missions to vehicles within a certain range.The communication terminals used by personnel are covered by wireless signals to ensure that personnel and vehicles that perform military,counter-terrorism,and disaster relief tasks are always under the command and control of higher-level command systems.

Most wireless broadband base stations use directional antennas to implement signal coverage.Ramanathan et al.[Ramanathan,Redi,Santivanez et al.(2005)] proposed the use of directional antennas for ad hoc networking was presented,which was an interacting suite of modular network and medium access control (MAC)-layer mechanisms for adaptive control of steered or switched antenna systems in an ad hoc network.In contrast to previous studies in which the barrier coverage problem was solved under the assumption of an omni-directional sensing model,Ssu et al.[Ssu,Wang,Wu et al.(2009)] presented a scheme for constructing k-barrier coverage using randomly deployed sensors with directional sensing model.A new MAC protocol for full exploitation of directional antennas was proposed in wireless networks,which introduced a circular directional transmission of the Request to Send (RTS) control packet,spreading around station information about the intended communication [Korakis,Jakllari and Tassiulas (2008)].A new MAC protocol that incorporates circular RTS and CTS transmissions was proposed [Jakllari,Broustis,Korakis et al.(2005)].The concept of the exclusive region (ER) was introduced to allow concurrent transmissions to explore the spatial multiplexing gain of wireless networks [Cai,Cai,Shen et al.(2010)].The use of directional antennas and beam steering techniques were investigated to improve the performance of 802.11 links in the context of communication between a moving vehicle and roadside Aps [Navda,Subramanian,Dhanasekaran et al.(2007)].Methods and systems for packet-by-packet directional mobile wireless transmission utilizing the plurality of directional antenna sectors,such that,the transmission of each packet is performed by at least one selected antenna sector.The direction of transmission is selected responsive to the direction in which the best electromagnetic signal reception was received [Ofek and Gavish (2011)].A method of operating a wireless access point having a configurable antenna system was proposed [Salo,Moore,Clark et al.(2011)].

An antenna apparatus comprises selectable antenna elements including a plurality of dipoles and/or a plurality of slot antennas (“slot”).Each dipole and/or each slot provides gain with respect to isotropic [Kish and Shtrom (2008)].The dipoles may generate vertically polarized radiation and the slots may generate horizontally polarized radiation[Kish and Shtrom (2015)].Mechanisms for wireless local area network coverage enhancement using dynamic antennas were provided [Kish (2014,2016)].A directional antenna-based leader-follower robotic relay system capable of building end-to-end communication was presented in complicated and dynamically changing environments[Min,Parasuraman,Lee et al.(2018)].The basic characteristics of communication systems based on HAP were considered [Alsamhi and Rajput (2015)],which outlined alternative network architecture scenarios for provision of wireless access to broadband communication services.With unsupervised self-organizing map (SOM) learning,an intelligent solution for both coverage planning and performance optimization was proposed [Gazda,?lapak,Bugár et al.(2018)].Genetic algorithm,differential evolution(DE),immune algorithm and particle swarm optimization were tested and compared to find the optimal coverage [Zhu and Gao (2017)].

According to the effective signals 3dB attenuation principle,the coverage angle of conical-polarized directional antennas used in maneuver command communication systems is generally 80 degrees.For better coverage,the vehicles usually elevate the directional antenna up to 8 m to 15 m by using the antenna rod.Limited by the weight of the antenna rod,generally,no more than 2 directional antennas are installed on the high antenna rod.Wireless signal coverage for mobile terminals is realized through the rotation of the antenna using two axial servo mechanisms.Therefore,how to reasonably formulate the directional antenna coverage strategy according to the mobile terminal dynamic distribution and guide the directional antenna dynamic coverage becomes a practical research topic.

In this paper,we make two major contributions:1) a directional antenna intelligent coverage method of point-to-point wireless coverage is proposed to overcome the problem of optimal coverage communication between points,and 2) To guarantee the effectiveness of optimal coverage communication between point-to-region,a directional antenna intelligent coverage method of point-to-point wireless coverage is given based on traversal optimization algorithm.The rest of the paper is organized as follows:Section 2 introduces typical application scenarios;Section 3 details directional antenna intelligent coverage method of point-to-point wireless coverage;Section 4 introduces the directional antenna intelligent coverage method of point-to-region wireless coverage based on traversal optimization algorithm;Section 5 presents simulation results;and we conclude the paper in Section 6.

2 Typical application scenarios

Maneuver command vehicle wireless broadband base station equipment with two plateshaped directional antennas,the initial state of the two directional antennas is parallel to the vehicle and the direction is perpendicular downward to vehicle,the directional antenna can be horizontal rotated ±90°(180°),pitch rotated±30°(60°),where the rotation is relative to the vehicle.The signal range of the directional antenna is horizontal±40°(80°).When one or more terminals around the command vehicle,the rotation scheme of the directional antenna needs to be designed so that the comprehensive reception effect of each point is the best.

Known conditions:longitude and latitude (B1,L1) and (B2,L2) of the vehicle and receiving points,and elevationH1andH2,azimuth angleθand pitch angleρof the vehicle in the initial state.We do not care about the roll angle of the vehicle,which is 0.Find the horizontal rotation angleαand pitch rotation angleβ.

Coordinate system:

Gauss-kruger plane rectangular coordinate system:take the equator and central meridian point as the origin of coordinateO,central meridian direction for theX-axis,south of the equator is negative,positive,north of north direction is positive.The equator is theY-axis,the central meridian is positive to the east,negative to the west,and positive to the east.You can convert the geodetic coordinate to the plane rectangular coordinate,which are(B1,L1) → (X1,Y1)and (B2,L2) → (X2,Y2).

Vehicle coordinate system:planexoyis parallel to the earth surface,that is,gaussian plane rectangular coordinate system,the initial plate position is the origin o,The forward direction of the car isX-axis forward,X-axis clockwise 90°isY-axis forward,vertical planexoyupward positive.The clockwise direction is E (East)-S (South)-W (West)-N(North)-E (East),which represents negative.The counter clockwise direction is E (East)-N (North)-W (West)-S (South)-E (East),which represents positive.

3 Point-to-point wireless coverage application scenario and design scheme

In this section,when the coordinate system is transformed,it does not need to change the difference between horizontal and vertical coordinate,but only changes some angles.And horizontal rotation and pitch rotation are independent and unaffected each other.We design the scheme in three steps:

Step1:X-axis of the vehicle coordinate system points north,and theY-axis points east,which is the azimuth angleθ=0and pitch angleρ=0of the vehicle.

Step2:azimuth angleθ∈ [0,360°)and pitch angleρ=0(azimuth within planexoy) of the vehicle.

Step3:azimuth angleθ∈ [0,360°)and pitch angleρ∈[-3 0°,3 0°]of the vehicle (Here positive up and negative down).

3.1 The first step of the scheme

The azimuth angleθ=0and pitch angleρ=0of the vehicle.As shown in Fig.1.

Figure1:Coordinate System Diagram when azimuth θ=0and pitch angle ρ=0

Coordinate (X1,Y1,H1)of vehicle in gauss plane,distance between vehicle coordinate and plateX3,the coordinate of the plate (X1 -X3,Y1,H1),receiving point(X2,Y2,H2),the coordinate of the receiving point projection (X2,Y2,H1),plate need to riseH3at work,plate coordinate (X1 -X3,Y1,H1 +H3)at work.

Because the height difference and the distance between two points do not change,so：

Facing vehicle forward,the left plate directional antenna is plate 1,the right plate directional antenna is plate 2.

Negative sign means clockwise rotation,positive sign means counterclockwise rotation.

(2) WhenY2-Y1＞0,plate 2 rotates.

(3) WhenY2-Y1=0,plate 1 or plate 2 can rotate,and then let plate 1 rotate.

WhenY2-Y1=0andX2-X1+X3＞0,plate 1 rotatesα=-90°.

WhenY2-Y1=0andX2-X1+X3＜0,plate 1 rotatesα= 90°.

Taking into account the above three aspects:

WhenY2-Y1≤0,plate 1 rotates

WhenY2-Y1＞0,plate 2 rotates

3.2 The second step of the scheme

The azimuth angleθ∈ [0,360°)and pitch angleρ=0of the vehicle.As shown in Fig.2.

Coordinate (X1,Y1,H1) of vehicle in gauss plane,distance between vehicle coordinate and plate X3,the coordinate of the plate(X1-X3cosθ,Y1+X3sinθ,H1),receiving point coordinate (X2,Y2,H2),the coordinate of the receiving point projection (X2,Y2,H1),plate need to raise H3 at work,the plate coordinate (X1-X3cosθ,Y1+X3sinθ,H1+H3) at work.Because the height difference and the distance between two points do not change,it is given the following:

Figure2:Coordinate System Diagram when of azimuth angle θ∈ [0,360°)and pitch angleρ=0

Facing vehicle forward,the left plate is plate 1,the right plate is plate 2.

WhenY2-Y1-X3sinθ=0andX2-X1+X3cosθ＞0,

WhenY2-Y1-X3sinθ=0andX2-X1+X3cosθ＜0,

(1) Whenα+kπ∈[-90°,90°],k=0 or 2,ifY2-Y1-X3sinθ≤0,plate 1 rotatesα+kπ;ifY2-Y1-X3sinθ＞0,plate 2 rotatesα+kπ.Negative sign means clockwise rotation,positive sign means counterclockwise rotation.

(2) Whenα+kπ∈[-90°,90°],k=1,ifY2-Y1-X3sinθ＜0,plate 2 rotatesα+kπ;ifY2-Y1-X3sinθ≥0,plate 1 rotatesα+kπ.

3.3 The third step of the scheme

The azimuth angleθ∈ [0,360°)and pitch angleρ∈[-3 0°,3 0°]of the vehicle.As shown in Fig.3.

Coordinate (X1,Y1,H1) of vehicle in gauss plane,distance between vehicle coordinate and plate X3,the coordinate of the plate (X1-X3cosρcosθ,Y1+X3cosρsinθ,H1-X3sinρ),receiving point coordinate (X2,Y2,H2),the coordinate of the receiving point projection (X2,Y2,H1-X3sinρ),plate need to rise H3 at work,the plate coordinate (X1-X3cosρcosθ,Y1+X3cosρsinθ,H1-X3sinρ+H3) at word.Here we can see that a simple geometric transformation cannot solve the design scheme,only the threedimensional coordinate transformation.

The vehicle attitude angles are known here:azimuth angleθ∈ [0,360°),pitch angleρ∈[-3 0°,3 0°]and roll angleγ=0.The coordinate of plate in vehicle coordinate system is set as (x1,y1,h1),and the coordinate of receiving point is (x2,y2,h2).According to the three-dimensional coordinate transformation matrix formula,we obtain:

Because the height difference and the distance between two points do not change in the vehicle coordinate system,we get the following:

Facing vehicle forward,the left plate is plate 1,the right plate is plate 2.

(1) Wheny2-y1＜0,plate 1 rotates.

Negative sign means clockwise rotation,positive sign means counterclockwise rotation.

(2) Wheny2-y1＞0,plate 2 rotates.

(3) Wheny2-y1=0,plate 1 or plate 2 can rotate,and then let plate1 rotate.

Wheny2-y1=0andx2-x1＞0,plate 1 rotatesα=-90°.

Wheny2-y1=0andx2-x1＜0,plate 1 rotatesα= 90°.

Taking into account the above three aspects:

Wheny2-y1≤0,plate 1 rotates

Wheny2-y1＞0,plate 2 rotates

It can be seen that the first and second step of design scheme are the special cases of the third step of design scheme,so the third step of design scheme is our general design scheme.

4 Point-to-region wireless coverage application scenario and design scheme

First,convert the coordinates of all receiving points and plates in the coverage region into the coordinates in the vehicle coordinate system,and figure out the angles between the connection line of all receiving points in the vehicle coordinate system from the projection point to the origin point o in the xoy plane and the forward direction of the Y-axis.Then,within [0,360°)scope of horizontal sector region,using optimization algorithm with angle bisector of 5 degrees step length,based on traversal methods,find out two horizontal sector regions with the most optimal coverage (maybe be one).According to the position of the two horizontal sectors,consider whether vehicle head is needed to move.Finally,aiming at all of the receiving points in two sectors (maybe one)found,figure out the projection angles of pitch angles of all receiving points in the vertical sector plane,and within the[-30°,30°]scope,for vertical sector angle bisectors,using optimization algorithm with 1 degree step length,based on traversal methods,find out a vertical sector region with the most optimal coverage.In particular,it is pointed out that the above statements are based on the vehicle coordinate system.We followed the following steps to design the scheme:

(1) The coordinate of the vehicle (X0,Y0,H0) in the gauss plane,the distance from the vehicle coordinate to plate isXh,then the coordinate of the plate(X0-Xhcosρcosθ,Y0+Xhcosρsinθ,H0-Xhsinρ),the plate need to riseHhat work,and the plate coordinate (X0-Xhcosρcosθ,Y0+Xhcosρsinθ,H0-Xhsinρ+Hh) at work.The coordinates of all receiving points are (X1,Y1,H1),(X2,Y2,H2),…,(XN,YN,HN) (N≥2).

Known vehicle attitude Angle:azimuth angleθ∈ [0,360°),pitch angleρ∈[-3 0°,3 0°]and roll angleγ=0.The coordinate of plate in vehicle coordinate system is set as (x0,y0,h0),and the coordinate of the nth receiving point is set as (xn,yn,hn) (1≤n≤N),so:

Figureout the counterclockwise angleαn(1 ≤n≤N,αn∈ [0,360°)) between the connection line of all receiving points in the vehicle coordinate system from the projection point to the origin point o in the xoy plane and the forward direction of the Y-axis:

(2) Within [0,360°)scope of horizontal sector region,using optimization algorithm with angle bisector of 5 degrees step length,based on traversal methods,find out two horizontal sector regions with the most optimal coverage (maybe be one).

Algorithm process:

Step1:First select the first horizontal sector,which has 72 possibilities.It is known when the ith case of the first horizontal sector,the degree of the counterclockwise anglebetween the angular bisector and the forward direction of Y-axisIn the ith case of the first horizontal sector Ωi,(k =0or1),it belongs to the region Ωi,it can be seen that the region Ωicovers the number of receiving pointsσi.

Step2:Then select the second horizontal sector.The first horizontal sector is defined as the region Ωi,which has 72-i possibilities.Ifandthen it belongs to the jth case of the second horizontal sector Θj,it can be seen that the region Θjcovers the number of receiving pointsτj.

Step3:Find out two horizontal sectors Ωiand Θjwith most optimal coverage,i.e.select max{σi+τj} (1 ≤ i ≤ 72and i + 1 ≤ j≤72).Now the degrees of counterclockwise angle between selected two horizontal sector angular bisector and the positive Y-axis are respectivelyθiandθj(1 ≤ i ≤ 7 2and i + 1 ≤ j≤72).

There are three cases of the maximum combination selected:

(1) Ifiis fixed,and j is any selected value greater than i,now only one region needs to be covered.If 90°≤θi≤270°,plate 1 rotatesα=θi-180°.If 0 ≤θi＜90°,plate 2 rotatesα=θi.If 270°＜θi＜360°,plate 2 rotatesα=θi-360°.

(2) If j is fixed,and i is any selected value less than j,now only one region needs to be covered.If 90°≤θj≤270°,plate 1 rotatesα=θj-180°.If 0 ≤θj＜90°,plate 2 rotatesα=θj.If 270°＜θj＜360°,plate 2 rotatesα=θj-360°.

(3) In addition to the above two cases,the several maximum combinations (including one)are selected.At this time,take any one of the maximum combinations,then there are two regions need to be covered.Then according to the value of the two angles to determine whether the vehicle head is moving,and here is knownθi＜θj.Negative sign means clockwise rotation,positive sign means counterclockwise rotation.

(a) If 0 ≤θi＜90°,there are three possible cases ofθj.

(b) If 90°≤θ≤270°, there are two possible cases of.

(3) For the two found horizontal sectors with most optimal coverage (maybe one),Ωiand Θjset as region A and B respectively.In region A,the coordinates of all receiving points in the vehicle coordinate system areIn region A,the coordinates of all receiving points in the vehicle coordinate system areThen the projection anglesof pitch angles of all receiving points in the vertical sector plane are calculated.

Within [-30°,30°]scope of vertical sector generated by bisector of region A and region B,using optimization algorithm with angle bisector of 1-degree step length,based on traversal methods,find out a vertical sector region with the most optimal coverage.

Algorithm process:

First step:for region A,the angleρAl= (Al- 3 1)1°(1≤Al≤61) between the bisector of the vertical sector ΔAl(1≤Al≤61) and the angle bisectorθi= (i- 1)5°(1≤i≤72) of the horizontal sector A,ifit belongs to region.We can see that region ΔAlcovers the number of receiving pointsεAl.Find out a vertical sector ΔAlwith the most optimal coverage,i.e.,select max{εAl} (1 ≤Al≤61).At this time,the pitch rotation angle of the plate in region A isβ=ρAl.

Second step:in the same way in region B,the angleρBl=± (Bl- 3 1)1°(1≤Bl≤61)between the bisector of the vertical sector ΔBl(1≤Bl≤61) and the angle bisectorθj= (j- 1)5°(i+ 1 ≤j≤72) of the horizontal sector B,ifit belongs to the region.We can see that the region ΔBlcovers the number of receiving pointsεBl.Find out a vertical sector ΔBlwith the most optimal coverage,i.e.,select max{εBl} (1 ≤Bl≤61).At this time,the pitch rotation angle of the plate in the region B isβ=ρBl.

5 Numerical example

In this section,we use two examples to demonstrate the performance of the proposed methods.

5.1 Example of point-to-point wireless coverage application scenario

The effectiveness of the proposed directional antenna intelligent coverage method of pointto-point wireless coverage is validated in this section.The initial conditions are listed in Tab.1,and other parameters of the vehicle,such as X3=2.5 m and H3=8 m.According to the information in Tab.1,the position information and status information of the vehicle are changed successively.The location information of the overwritten target point is fixed,as shown in Tab.2.The simulation results are obtained by software simulation,that is,the horizontal rotation angleαand pitch rotation angleβof the directional antenna on both sides of the vehicle to cover the target point,as shown in Tab.3.

Table1:The initial conditions of the vehicle

40 116 0 4 40 0 0 20 0 5 0 41 116 0 4 40 0 0 20 0 10 0 42 116 0 4 40 0 0 20 0 -10 0 43 116 0 4 40 0 0 20 0 -5 0 44 116 0 4 40 0 0 20 0 0 5 45 116 0 4 40 0 0 20 0 0 10 46 116 0 4 40 0 0 20 0 0 -10 47 116 0 4 40 0 0 20 0 0 -5

Table2:The location information of the target point

Table3:The horizontal rotation angleαand pitch rotation angleβof plate 1 and plate 2

26 -3 -30 — —27 -3 90 — —28 -7 90 — —29 -13 90 — —30 7 90 — —31 2 90 — —32 -7 90 — —33 -13 90 — —34 7 90 — —35 2 90 — —36 -3 -5 — —37 -3 -10 — —38 -3 10 — —39 -3 5 — —40 -7 0 — —41 -13 0 — —42 7 0 — —43 2 0 — —44 -7 0 — —45 -13 0 — —46 7 0 — —47 2 0 — —

5.2 Example of point-to-region wireless coverage application scenario

The effectiveness of the proposed directional antenna intelligent coverage method of point-to-point wireless coverage based on traversal optimization algorithm is validated in this section.The initial conditions are listed in Tab.4,and other parameters of the vehicle,such as X3=2.5 m and H3=8 m.According to the information in Tab.4,the position information and status information of the vehicle are changed successively.The location information of the overwritten target points is fixed,as shown in Tab.5.The simulation results are obtained by software simulation,that is,the rotation angle of the vehicle and the horizontal rotation angleαand pitch rotation angleβof the directional antenna on both sides of the vehicle to cover the target points,as shown in Tab.6.

Table4:The initial conditions of the vehicle

Table5:The location information of the target points

Table6:The rotation angle of the vehicle and the horizontal rotation angle αand pitch rotation angleβof plate 1 and plate 2

6 Conclusion

This paper proposed a directional antenna intelligent coverage method based on traversal optimization algorithm,by using three-dimensional coordinate transformation,based on the actual demand of maneuver command system,provided the wireless signal coverage schemes for point-to-point and point-to-region,determined the required horizontal rotation angle and pitch rotation angle of the directional antenna intelligent coverage,and laid the foundation for the performance of wireless broadband communication in the maneuver command communication system.

Acknowledgement:This research was funded in part by the National Natural Science Foundation of China (61871140,61872100,61572153,U1636215,61572492,61672020),the National Key research and Development Plan (Grant No.2018YFB0803504),and Open Fund of Beijing Key Laboratory of IOT Information Security Technology(J6V0011104).