Research Article A Lightweight Neighbor-Info-Based Routing …downloads.hindawi.com/journals/tswj/2014/601913.pdf · 2019. 7. 31. · Research Article A Lightweight Neighbor-Info-Based

Research ArticleA Lightweight Neighbor-Info-Based Routing Protocol forNo-Base-Station Taxi-Call System

Xudong Zhu Jinhang Wang and Yunchao Chen

School of Computer Science amp Information Engineering Zhejiang Gongshang University Hangzhou 310018 China

Correspondence should be addressed to Xudong Zhu zhuxdzjgsueducn

Received 26 October 2013 Accepted 28 November 2013 Published 9 March 2014

Academic Editors W Sun G Zhang and J Zhou

Copyright copy 2014 Xudong Zhu et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Since the quick topology change and short connection duration the VANET has had unstable routing and wireless signal qualityThis paper proposes a kind of lightweight routing protocol-LNIB for call system without base station which is applicable to theurban taxis LNIB maintains and predicts neighbor information dynamically thus finding the reliable path between the source andthe target This paper describes the protocol in detail and evaluates the performance of this protocol by simulating under differentnodes density and speed The result of evaluation shows that the performance of LNIB is better than AODV which is a classicprotocol in taxi-call scene

1 Introduction

The VANET has characteristics of mobile ad hoc networksuch as self-organization flexible structure multihop rout-ing dynamic changes of network topology and need ofgood scalability Special application environment such asnarrow road high density node distribution high-speednode moving and other factors will directly influence theinformation transmission ability of VANET network whichleads to the increase of packet loss and delay Meanwhile thelimitedwireless channel and huge network scale challenge thedata transmission of VANET

The key to solve the above problems is how to designa routing protocol [1ndash7] Since the nodes in VANET are ofhigh mobility it results in connection failure while applyingrouting protocol of the traditional MANET [8ndash10] such asAODV [11ndash13] andDSR [14 15] into theVANET thus leadingto delay or even failure to transmit information to the targetnode

Due to the special environment in VANET it cannot havea widely applicable routing algorithm The typical algorithmin VANET such as GSR routing protocol involves eachnode storing the neighbor lists topology table next hoptable and distance table All of them maintain the stateinformation of adjacent nodes and choose the appropriate

router according to the location and topological informationIn small network with high mobility and limited bandwidththe performance of transmission is good However it requiresthe node to maintain the network topology And with theincrease of network size the routing information that needsto be exchanged will increase exponentially Another type ofalgorithm such as the GPSR [16 17] is based on positionIt depends on the overall geographical location informationsearch system It cannot work without GPS

When applied to the urban taxi-calling scene theVANETvehicle network has the following characteristics (1) Thedensity distribution of vehicle is uneven Places such as thebusiness center theaters and bus stations are dense The tra-ditional VANET routing protocols have serious informationchannel congestion problem (2)Thecalling passenger has nospecial requirements to the not-taken taxis so all the nearbytaxis can serve While the traditional VANET routing proto-cols always have designated transmission target or specifiesthe routing service of all nodes in the target area whichwill lead to huge routing overhead further deteriorating thechannel congestion problem (3) The data transmission istime valid Passengersrsquo calls need to be responded to in ashort time while the routing connection time is fairly long insome of the traditional VANET routing protocols Thereforeit cannot effectively find not-taken taxis with such application

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 601913 9 pageshttpdxdoiorg1011552014601913

2 The Scientific World Journal

and will have bad effects on passengersrsquo experiences Wedescribe some of the work roughly in [18]

This paper aims to solve the quick topology change shortconnection duration and unstable wireless signal quality ofthe VANET network thus proposing a kind of lightweightrouting protocol applicable to the urban taxi-call withoutbase stations The protocol maintains and predicts neighborinformation dynamically in order to find the reliable pathbetween the source and the target This paper describes theprotocol in detail and evaluates the performance of thisprotocol by simulating under different nodes density andspeedThe result of evaluation shows that the performance ofLNIB is better than that of AODV which is a classic protocolin taxi-call scene

The second chapter analyzes the application and proposesthe model the third chapter describes the routing protocoland its algorithm the fourth chapter is about the experi-ment and data analyses chapter five concerns other relatedresearch the last part will draw a conclusion

2 Transmission Mode and Analyses

In the taxi-calling scene the vehicle network has two setstaxi nodes 119876 = 119902

1 1199022 119902119899 and passenger nodes 119875 =

1199011 1199012 119901119898 From the start of the call to get on the car

or the call to cancel a connection should be set up in thenetwork Because the passenger always waits at the originalplace or moves slowly suppose 119901 is a static node And 119901 onlyacts as the initiator of data transmission or receiver not asmediator in other routings The node 119902 can send receive oract as a routing node to transmit data Assume that the speedscalar of each node in 119876 is |V|

When 119901 initiates a call the message transits through thetaxi nodes so 119901 can quickly find nearby not-taken cars node119902119904that can meet the requirementsSupposing there are two nodes 119886 and 119887 in the network the

signal coverage radii for them are respectively 119877119886and 119877

119887 If

the distance between 119886 and 119887 is 119863119886119887le min(119877

119886 119877119887) it can

be called ldquomeetrdquo To be more general assuming that signalcoverage radius of each node in the network is 119877 then ldquomeetrdquoin time 119905 means 119863

119886119887(119905) le 119877 Define 119867

119886119902119904

as the minimalnumber of hops to transmit message from 119886 to 119902

119904 Among

all 119902119904that get the call request119867

119886is the lowest of119867

119886119902119904

21 Prediction Based on Neighbor Information In order topercept the current meet nodes in real time 119902 needs tosend broadcast packets to notice their own state informationperiodically In the starting time 119905 of every broadcast cycle119902 measures their own motion state including the speed thecurrent position and other information According to theabove information 119902 predicts the coordinates at the time of119905 + 119905119891and broadcasts the position The broadcast cycle is 119905

119887

If 119905119887is small then the channel will be occupied by a large

number of broadcast packets thus influencing the normaldata transmission However large 119905

119887will lose the predic-

tion value due to the frequent changes in actual situationTherefore 119905

119887should be set properly such as 10 seconds A

broadcast cycle can be divided intomultiple correction cycles

The node in a correction period measures their movementstate While finding the coordinatesrsquo different Δ119904 between thecurrent forecast coordinate at 119905 + 119905

119891and the last broadcast

coordinates surpasses it indicates that the vehiclersquos drivingcondition changes If Δ119904 is greater than a certain value thenode broadcasts the position again to correct the predictposition of itself in neighbor nodesrsquo state table thus to ensurethe prediction accuracy Suppose the correct period is 119905

119903

Meanwhile if 119902 receives the position broadcast of thenearby nodes it maintains an adjacent link (see Table 1) torecord node information that meets with 119902 It can be seenfrom the table that 119902

2measures its position and velocity at

131112101584036 and broadcasts 1199021receives the position broadcast

If11986311990211199022

(119905) le 119877 then it can be predicted that at 119905 + 119905119891 1199021and

1199022will keepmeeting If 119902

2is not in the table 119902

1adds the infor-

mation of 1199022to the table and sets 119902

2to be active If 119902

2is already

in the table update the information of 1199022 When 119902

1receives

the correction broadcast of 1199022 the position information of 119902

2

also needs updating If it can be predicted that 1199021and 1199023will

not meet at 119905 + 119905119891 set 119902

3to be inactive As to the inactive

node in the table if no broadcasts are received in more thanone broadcast cycle then delete the entry of this inactivenode Each time the passenger calls a taxi several links will beproduced If 119902

1and 1199023are neighbors and are both in one link

then they set up link ID in the entry for each other in theirown table Link ID is a large number that is randomly gener-ated It can be assumed that it is unique in a limited region

When 1199021receives the broadcast of neighbors at time 119905 it

will predict coordinates of itself and neighbor nodes at 119905 + 119905119891

respectively If the two cars can keep communication at thattime (such as 119902

2) the communication is effective Therefore

1199021stores the information of 119902

2in the table otherwise discards

it (such as the 1199023)

In order to provide the position information and routingof not-taken taxis the hop distance should be introducedwhen 119902 node is broadcasting message (including positionand correction broadcast) Periodically 119902

119904sets 119867

119902119904

to 0 andsends broadcastThe 119902

119904discards any broadcast information it

received without processing The 119902 sets119867119902value toinfin when

no neighbor nodes can reach 119902119904node When 119902

1receives the

broadcast of 1199022with the active state if 119867

1199022

+ 1 lt 1198671199021

1199021

modifies the1198671199021

value to1198671199022

+ 1Once 119867

1199021

changes 1199021will spread to notify neighbor

nodes to be updated by periodical breakfast But each cyclecan only update 1 hop on the link If 119867

11990211199022

= 119899 it needs 119899cycle to update119867

1199022

In order to improve the broadcast speed of119867 the sending

phase of each cycle is divided into two time slices The nodeof119867 changes but no broadcast will be broadcasted at the firsttime slice If the 119867 value has no change after last broadcastthe node broadcasts in the second time slice Thus the valueof119867may spread 2 hops in a cycle For the length of link willbe limited in 3-4 hops in the actual system two cycles cancomplete the information disclosure of not-taken taxis by theimproved broadcast speed

22 Links Setting and Handshake When 119901 launches the callit needs to find suitable not-taken taxis 119902

119904as soon as possible

and make an appointment In this process the following

The Scientific World Journal 3

Table 1 State of the 1199021rsquos Neighbor Nodes

Neighbor 119867119902119899119902119904

Position Direction of speed Link ID Reliability Measuringtime State

1199022

3 120213476E30321768N 119889

1199022

182378627 094 131112101584036 Active

1199023

5 120213484E30321775N 119889

1199023

452766732 083 131037101584034 Inactive

p

qa(H = 2)

qb(H = 5)

qc(H = 3)

qd(H = 1)

(a)

qs

q998400a(Dp1q119904= 200m)

q998400b(Dp3q119904= 300m)

(b)

Figure 1 (a) If there are the 119902 nodes within the single hop range of 119901 then they shake hands and choose one as 119902119886that has minimal hop

distance to 119902119904to make an appointment (b) If there are several 119902 nodes around 119902

119904and several 119901 nodes send the appointment requests then

they shake hands and choose the nearest 119901 node to response

questions need to be solved First how to find 119902119904in the

shortest time and establish the link to 119902119904 Secondly if there

are several 119902119904nodes how to choose one of the most suitable

ones to make an appointmentThe simplest method is to use the broadcast to send out

the call until a node of 119902119904receives the request and returns a

response The response will go backtracking to the 119901 nodeIf 119901 receives several responses then choose one from themafter which appointment confirmation will be sent to thechosen node through the path just set up Meanwhile itwill send negative responses to other not-taken taxis Thismethod is easy to be implemented but in the real VANETscene there are serious problems the message must pass thewhole link three times request response and appointmentOn the one hand it will lead to serious delay and difficulties inkeeping the link on the other hand the flooding of breakfastwill deteriorate the network environment and influence thenormal communication

This paper proposes a two-end handshake agreement togreat link (show as Figures 1 and 2) According to the neighbornodesrsquo information described in Section 21 each node canknow the nearest (by hop distance) 119902

119904and the shortest route

to arrive at the node If 119901 sending the request broadcast itsneighbor 119902 node which receives 119901rsquos breakfast directly canjudge whether it can reach 119902

119904or not In fact it is supposed

that the whole data transmission is a single route (the nodeon the link will transmit a message to only one neighbor

p qc qc qs

Figure 2 The two-end handshake agreement

node) Once 119902 is identified as the first hop the routing from119901 to 119902

119904will also be established The 119902 can directly send a

request response to the 119901 If 119901 receives responses from several119902 nodes it chooses a 119902 node as 119902

119886to make appointment

confirmation and send a veto appointment to other response119902 After that 119902

119886accepts the confirmation and sends it to the 119902

119904


based on the routing information that is to transmitmessageto the neighbor 119902 node in which 119867

119902= 119867119902119886

+ 1 On therouting node 1199021015840 will record the information of last hop whilereceiving the message Meanwhile transmit to the next hopwhich119867

119902= 1198671199021015840 + 1 until sent to the node which119867

119902= 0 that

is 119902119904The 119902119904end of the link also needs handshaking If several

neighbor 119902 nodes in which 119867119902= 1 are for the same 119902

119904

node they will send appointment requests to the 119902119904 and the

119902119904sends a confirmation response to one of them and negative

responses to othersThe two-end handshaking method can reduce the three

times handshaking to two times thus reducing the risk ofdelaying and disconnectionMeanwhile the broadcast can becontrolled in 1 hop and can avoid the flooding

23 Disconnection Suppose 119867119902119904

= 0 1198671199021

= 1 1198671199022

= 2 and1198671199023

= 3 If 1199022receives the position correction information

from 1199021 the adjusted position predictions indicate that 119902

1will

lose contact with 1199022 Since 119867

1199021

is the minimum 119867 stored in1199022 after 119902

2node deletes the 119902

1 it modifies its own119867 value to

infin and triggers an extra position correction broadcast Alsowhen 119902

3receives the position correction by this broadcast it

continues the same operationIn the communication process the effectiveness of link

should be guaranteed from the sending of 119901rsquos request to119902119904rsquos response return to 119901 Once a pair of nodes on the link

are disconnected it should be processed correspondentlyThe relatively ideal way is to find the third node beforedisconnection and to maintain the link Another simplemethod is to notify 119901 and 119902

119904to abandon the appointment on

both ends Thus it can avoid feedback loss which will resultin information consistency Then the 119901 initiates the requestprocess again

As the vehiclersquos speed is fast and unstable the time oflink maintains a relatively short time The frequently brokenlinks will lead to repeated reconnection To avoid this higherreliable links are required So in the 119902rsquos neighbor nodes statetable the reliability attribute is added for each neighbor nodeThe reliability refers to the prediction accuracy at 119905 + 119905

119891and

the help to effective datagram transmission on the link Itmainly depends on the following two conditions (1) during 119905to 119905 + 119905

119891period the relative position between 1199021015840 and 119902 If the

distance is far on the one hand the weak signal can lead totransmission instability on the other hand since 1199021015840 has beenclose to the edge of the 119902 communication range the slightchange of the vehicles will make 1199021015840 out of 119902rsquos communicationrange and cause broken connection If 1199021015840 and 119902 are closethe data transmission will take place in a short distance Thedatagramwill not move a lot in geographical location thus itinfluences the efficiency of data transmissionThus supposing1198801199021199021015840(1199051015840) = 2|119863

1199021199021015840(1199051015840) minus 119877|119877 refers to the transmission

reliability of 119902 and 1199021015840

1198801199021199021015840 (119905 119905 + 119905

119891) =

integration(119905 119905 + 119905

119891) (1)

Modify the condition of correcting 119867119902in Section 21

Given the reliable threshold 119903 isin [0 1] and after 1199021node

receives the broadcast of 1199022node if state (119902

2) = active119867

1199022

+

1 lt 1198671199021

and1198801199021199021015840(119905 119905 + 119905

119891) gt 119903 then modify the119867

1199021

value tobe 1199022+ 1

3 Protocol Implementation

In order to further introduce the implementation of theprotocol the pseudocode algorithms of taxi 119902 node andpassenger 119901 node are given respectively in this section Tobe simple based on the discussion in the second section thefollowing several types of datagram in the taxi-call networkwill be referred to

Broadcast (119871 119881119867 119905119888) represents position broadcast The

taxi node sends periodically and the nearby taxi nodereceives1198721minus6

represents the six kinds of datagrams in the two-endhandshaking protocol after the passengers make a request119872119890represents the cancelation of the reserved datagram

while finding the abnormal disconnectionAlgorithm 1 is divided into two parts The timer gets

the position and speed information for a short time (eg3 seconds) If the interval exceeds 119905

119891 then send broadcast

to the nodes around According to the current measureddata the position at 119905 + 119905

119891can be predicted If there exists

significant difference between the position and the position ofthe last broadcast then send broadcast without consideringwhether the time intervals exceed 119905

119891or not The timer will

also inspect the neighbor node that is not updated over timein the adjacency list and set these nodes as inactive Sincethe time in the record is the position measuring time toconsider the communication delay the overtime windowwillbe slightly amplified to 11119905

119891 If not updated for more than

two broadcast cycles then delete the nodeAs for the inactive nodes check whether they are in the

current communication connection If it is true then send119872119890

to other connected nodes to cancel the conformationThe other part of Algorithm 1 is the listener After the

listener receives a datagram heshe judges data types If it isthe position broadcast datagram then update the list Oncethe predicted node position changes are identified in thecurrent connection and in a short time will overpass thescope of communication and then notify other nodes on theconnection to cancel the appointmentWhen accepting othertypes of datagram again transmit or respond based on theprotocol

Algorithm 2 mainly includes two timers and a listenerWhen initiating the request timer

1is set At the same time

the listener will put the received response to the responsequeue When timer

1is triggered it checks the queue If the

queue is empty it means no response and it sends the requestagain Otherwise it chooses the response that has the nearesttransmission distance from passengers to not-taken taxis inorder to make appointment And it simultaneously sendsveto to other response nodes After sending the appointmentdatagram set timer

2 Once no appointment conformation

1198724in a certain time 119872

4 then the timer

2will be launched

and send request1198721again Attention here once the listener

receives an 119872119890 the datagram cancellation is caused by


Initialization 119905 = 0Initiate the prediction position 119878 = 0Initialization 119867 = infinSet timerTimer task()

Obtain the current position L speed V time 119879119888

119867new = 119867If (no-load)119867new = 0

Calculate prediction position 1198781015840 at (119905 + 119905119891)

If (119905119888minus 119905ge119905119891)

119867 = 119867newbroadcast(L V H 119905

119888)

119905 = 119905119888

119878 = 1198781015840

else if (|119878 minus 1198781015840| larger than threshold 119867 minus 119867new⟨⟩0)119867 = 119867new

broadcast(L V H 119905119888)

119905 = 119905119888

119878 = 1198781015840

For each node q in tableget qrsquos prediction time 119905

119902

if (state(q) == active ampamp 119905119888minus 119905119902ge 11119905

119891)

state(q) = inactiveif (q have the link ID)send119872

119890to other node which have the same lnik ID as q

If (119905119888minus 119905119902ge 2119905119891)

Remove q from table

Update H

Count = 0 reset 0 after passengers getting off or appointment cancellationBlock listen(Message)

Switch typeof(Message) Case119872

119887

update tableupdate Hif q node that sends119872

119887gets out of the communication range and it has link ID in the table

send119872119890to other node

which have the same link ID as qbreak

Case1198721

If (119867 lt infin)send1198722back

breakCase119872

3

If (Message == Reserve)If (119867 == 0 ampamp count == 0)

Count = 1send119872

4(Agree or Disagree) back

else if (119867 == 1)Set link IDsend119872

3to all q in table which119867

119902= 0

else

Algorithm 1 Continued


Set link IDsend119872

3to one q which119867

119902= 119867 minus 1

Case1198724

If (Message == Agree)Send119872

4forward to q which119867

119902= 119867 + 1

and have the same link IDdelete link ID

If (119867 == 1)Send Confirm back

Default

Algorithm 1 Algorithm of taxi node

Initiation queue = emptyCall taxi

Get its position LBroadcast(119872

1)

Set Timer1()

Timer1 task()If (queue = empty)

Call taxi()elseChoose the nearer hop qProduce link IDSend119872

3(Reserve link ID) to q

Send1198723(Negative) to other

Set timer2

Timer2 task() Call taxi() Block listen(Message)Switch typeof(Message)

Case1198722

Add q to queueBreak

Case1198724

Cancel Timer2Break

Case119872119890

Set Timer2 current timeBreak

Default

Algorithm 2 Algorithm of passenger node

connection errorThen immediately start the timer2and send

request again

4 Performance Analysis

In order to evaluate the performance of the proposed routingprotocol the paper uses NS2 and VanetMobiSim to simulate

TheNS2rsquosmain parameters are shown in Table 1The sim-ulation scene size is 5times 5 square kilometers InVanetMobiSimsimulation the scene size is 5times 5 square kilometers too In thetotal area there are 20 traffic signals and the entire simulationarea is divided into several regions In every region the densityof streets and the allowed maximum speed are different Theregions which have higher street density have lower allowedmaximum speed When vehicles get into the correspondingregion they choose the speed from street allowed maximumspeed and self-allowedmaximum speed with a low one In allof our simulations the empty taxis account for 40

We set the interval of route maintain message 119879119887to be

equal to 10 s and then set the maximum speed of taxi nodesto be equal to 60 kmh When we adjusted the density of taxinodes we got the probability of passenger node 119875 to findempty taxi node 119879

119863and the probability of node 119875 to receive

the message from 119879119863as shown in Table 3

As shown in Table 3 when node density is too low thetransmission range will be so small that it is hard to maintainthe information of nodes for a long time Hence when 119875appears the number of nodes that 119875 can communicate withis small and the time of link is short so that it is hard tocommunicate with 119879

119863 As the node density becomes higher

situations are getting better but some nodes have highervelocity which leads tomore failure Because the links chosenare the links that have long duration so the probability ofnode 119875 receiving acknowledgement messages from node 119879

119863

is pretty highThen if we fix the density of taxi nodes as 5 per km2 and

fix the transmission range as 500m we will get the relation ofthe maximum speed and the successful ratio

We called it successful calling when the passenger nodefinds the empty taxi node In Figure 3 we could see that whenthemaximumspeed of taxi is equal 60 kmh it has the highest


74

76

78

80

82Su

cces

sful r

ate (

)

Maximum speed (kmh)40 50 60 70 80 90 100

04

06

08

1

12

14

Link

bro

ken

ratio

()

Successful rateLink broken ratio

Figure 3 The relation of the maximum speed of taxi nodes and theratio of passenger node contacting empty taxi nodes successfully

successful ratio which enables the passenger node to find theempty taxi nodes This is because when the nodersquos movingspeed is low the node can contact with fewer other nodesAnd when the nodersquos moving speed is high the networktopology changes fast which causes fewer available routinglink and thus causes lower successful calling

Figure 4 shows the impact of nodersquos moving speed on theamount of switching packets of entire network

As shown in Figure 4 the amount of switching packetsgrows up as the vehicle movement speed increases Thisis because when the speed of node movement increases itcauses more correcting message resulting in the increaseof network data traffic In addition in one simulation therouting overhead is higher at the beginning and graduallydeclines over time This is because when the simulationstarts all taxi nodes are active at the same time and all taxinodes broadcast at the same time which causesmore channelcollision leading to an increasing number of retransmissionsAs time progresses due to the correcting message the taxirouting maintenance cycles gradually stagger and the entirenetwork routing overhead declines

Thenwe adjust the density of taxi nodes in the regionTheaverage density of taxi nodes is set at 1ndash6 per square kilometerand the vehiclemaximumspeed is set at 60 kmh and then theresults are shown in Figure 5

As shown in Figure 5 when the taxi nodes are scarcethe rate of the success calling drastically reduces Whileincreasing the number of taxi nodes the rate of success callingimproves accordingly This is because when the number oftaxi nodes is too small there is no taxi node around passengernode so that the passenger node cannot contact with anynode resulting in more calling failure When the numberof taxi nodes increase and the passenger node sends anappointment request the number of alternative routing pathsincreases so the node can choose a more stable routing pathto delivery packet thereby the rate of success calling willincrease

2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh

Figure 4 The impact of nodersquos moving speed on the amount ofswitching packets of entire network

20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()

Successful ratioLink broken ratio

The density of taxi nodes (km2)

Figure 5 The impact of nodes density on successful ratio

Table 2 The NS2 parameters

Parameters ValuesLoss model PropagationTwoRayGroundPhysical model PhyWirelessPhyExtAntenna AntennaOmniAntennaTransmission rate 2MbpsNetwork protocol IEEE 80211

At last we control node velocity between 0 and 20msinterval of 119879

11988710 s transmission range is 500m and the

density is 4 per square kilometers Compared to AODV(show as Table 4) the results are shown in Table 2 We cansee that the proposed routing protocol performs better than


Table 3 The impact of nodes density and transmission range on successful calling ratio

Transmission rangeDensity of taxi

4 6The probability to

find 119879119863

The probability toreceive from 119879

119863

The probability to find119879119863


119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946

Table 4 Compare with AODV

CBLIGR AODVDelivery rate() 611 523Control messagepacket 12068 18150

AODV More importantly our protocol communication datais scattered throughout the network while AODV is relativelyconcentrated As a result our protocol performs better in thechannel collision It is because AODV requires a great dealof broadcast to maintain the entire link routing informationand has no efficient methods to deal with the disconnectionof links

5 Conclusion

This paper proposes a routing protocol for taxi-calling appli-cation Firstly it analyzes scenes of taxi-calling applicationand studies the differences between the common vehicleapplication scene and the taxi-calling application sceneSecondly it proposes the routing information maintainingalgorithm based on position prediction which performsbetter reliability Thirdly a self-network forming method fortaxi-calling application is drawn up

Our protocol queries the destination node by nodesrsquokeeping the information of the hop count to destination anddecreases the routing cost Meanwhile the validity of routesis guaranteed by predicting the future position of themselvesand their neighbors

This protocol has also been evaluated by a traffic sim-ulator The results indicate that our protocol can efficientlyfind the target nodes in the area It has also been found thatthe number of broadcasts is affected by nodesrsquo velocity Andthe fact that our protocol generates 30 less messages thanAODV has been proven here

As to future work our protocol can probably be extendedto solve the low delivery rate problem when the density ofvehicle is low

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

This work is supported in part by the Natural ScienceFoundation of China ldquoResearch on the snapshot data securitystorage technology for authorization of releaserdquo no 61100057

References

[1] C Rezende R W Pazzi and A Boukerche ldquoAn efficientneighborhoood prediction protocol to estimate link availabilityin VANETsrdquo in Proceedings of the 7th ACM International Sym-posiumonMobilityManagement andWireless Access (MobiWACrsquo09) pp 83ndash90 Tenerife Spain October 2009

[2] T Zahn G OrsquoShea and A Rowstron ldquoFeasibility of contentdissemination between devices in moving vehiclesrdquo in Proceed-ings of the 5th International Conference on Emerging NetworkingExperiments and Technologies (CoNEXT rsquo09) pp 97ndash108 RomeItaly December 2009

[3] N Wisitpongphan F Bai P Mudalige and O K Tonguz ldquoOnthe routing problem in disconnected vehicular ad Hoc net-worksrdquo in Proceedings of the 26th IEEE International Conferenceon Computer Communications (IEEE INFOCOM rsquo07) pp 2291ndash2295 Anchorage Alaska USA May 2007

[4] A Boukerche H A B F Oliveira E F Nakamura and A AF Loureiro ldquoVehicular Ad Hoc networks a new challenge forlocalization-based systemsrdquoComputer Communications vol 31no 12 pp 2838ndash2849 2008

[5] C E Perkins and P Bhagwat ldquoHighly dynamic destination-sequenced distance-vector routing (DSDV) for mobile com-putersrdquo in Proceedings of the Conference on CommunicationsArchitectures Protocols and Applications (SIGCOMM rsquo94) pp234ndash244 1994

[6] T Spyropoulos T Turletti and K Obraczka ldquoRouting indelay-tolerant networks comprising heterogeneous node pop-ulationsrdquo IEEE Transactions on Mobile Computing vol 8 no 8pp 1032ndash1047 2009

[7] C Lochert M Mauve H Fuszligler and H Hartenstein ldquoGeo-graphic routing in city scenariosrdquo Mobile Computing andCommunication Review vol 9 no 1 pp 69ndash72 2005

[8] M Jerbi and S M Senouci ldquoTowards efficient routing invehicular Ad Hoc networksrdquo in Proceedings of the 3rd IEEEInternational Workshop on Mobile Computing and Networking2006

[9] H Menouar M Lenardi and F Filali ldquoAn intelligentmovement-based routing for VANETsrdquo in Proceedings ofthe ITS World Congress London UK October 2006

[10] K Shafiee and V C M Leung Connectivity-Aware Minimum-Delay Geographic Routing with Vehicle Tracking in VANETsElsevier BV 2010


[11] J Haerri F Filali and C Bonnet ldquoPerformance comparisonof AODV and OLSR in VANETs urban environments underrealistic mobility patternsrdquo in Proceedings of the Med-Hoc-Net2006 5th Annual Mediterranean Ad Hoc NetworkingWorkshopLipari Italy June 2006

[12] C E Perkins and E M Royer ldquoAd-hoc on-demand distancevector routingrdquo in Proceedings of the 2nd IEEE Workshop onMobile Computing Systems and Applications (WMCSA rsquo99) pp90ndash100 New Orleans La USA February 1999

[13] T W Chen and M Gerla ldquoGlobal state routing a new routingscheme for Ad-hoc wireless networksrdquo in Proceedings of theIEEE International Conference on Communications (ICC rsquo98)vol 1 pp 171ndash175 Atlanta Ga USA June 1998

[14] B Karp and H T Kung ldquoGPSR greedy perimeter statelessrouting for wireless networksrdquo in Proceedings of the 6th AnnualInternational Conference on Mobile Computing and Networking(MOBICOM rsquo00) pp 243ndash254 Boston Mass USA August2000

[15] D B Johnson D A Maltz and J Broch ldquoDSR the dynamicsource routing protocol for multi-hop wireless Ad hoc net-worksrdquo in Ad Hoc Networking C E Perkins Ed chapter 5 pp139ndash172 Addison-Wesley New York NY USA 2001

[16] D B Johnson D A Maltz and J Broch ldquoDSR the dynamicsource routing protocol for multi-Hop wireless ad hoc net-worksrdquo in Ad Hoc Networking C E Perkins Ed chapter 5 pp139ndash172 Addison-Wesley New York NY USA 2001

[17] Z Wei and S Weibin ldquoResearch of GPSR routing protocol forwireless sensor networksrdquo Electronic Measurement Technologyvol 33 no 9 2010

[18] GWei Y Chen andX Zhu ldquoA vanet-oriented routing protocolfor intelligent taxi-call systemsrdquo in Proceedings of the IEEE 14thInternational Conference on Communication Technology (ICCTrsquo12) pp 41ndash45 Chengdu China November 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



and will have bad effects on passengersrsquo experiences Wedescribe some of the work roughly in [18]

This paper aims to solve the quick topology change shortconnection duration and unstable wireless signal quality ofthe VANET network thus proposing a kind of lightweightrouting protocol applicable to the urban taxi-call withoutbase stations The protocol maintains and predicts neighborinformation dynamically in order to find the reliable pathbetween the source and the target This paper describes theprotocol in detail and evaluates the performance of thisprotocol by simulating under different nodes density andspeedThe result of evaluation shows that the performance ofLNIB is better than that of AODV which is a classic protocolin taxi-call scene

The second chapter analyzes the application and proposesthe model the third chapter describes the routing protocoland its algorithm the fourth chapter is about the experi-ment and data analyses chapter five concerns other relatedresearch the last part will draw a conclusion

2 Transmission Mode and Analyses

In the taxi-calling scene the vehicle network has two setstaxi nodes 119876 = 119902

1 1199022 119902119899 and passenger nodes 119875 =

1199011 1199012 119901119898 From the start of the call to get on the car

or the call to cancel a connection should be set up in thenetwork Because the passenger always waits at the originalplace or moves slowly suppose 119901 is a static node And 119901 onlyacts as the initiator of data transmission or receiver not asmediator in other routings The node 119902 can send receive oract as a routing node to transmit data Assume that the speedscalar of each node in 119876 is |V|

When 119901 initiates a call the message transits through thetaxi nodes so 119901 can quickly find nearby not-taken cars node119902119904that can meet the requirementsSupposing there are two nodes 119886 and 119887 in the network the

signal coverage radii for them are respectively 119877119886and 119877

119887 If

the distance between 119886 and 119887 is 119863119886119887le min(119877

119886 119877119887) it can

be called ldquomeetrdquo To be more general assuming that signalcoverage radius of each node in the network is 119877 then ldquomeetrdquoin time 119905 means 119863

119886119887(119905) le 119877 Define 119867

119886119902119904

as the minimalnumber of hops to transmit message from 119886 to 119902

119904 Among

all 119902119904that get the call request119867

119886is the lowest of119867

119886119902119904

21 Prediction Based on Neighbor Information In order topercept the current meet nodes in real time 119902 needs tosend broadcast packets to notice their own state informationperiodically In the starting time 119905 of every broadcast cycle119902 measures their own motion state including the speed thecurrent position and other information According to theabove information 119902 predicts the coordinates at the time of119905 + 119905119891and broadcasts the position The broadcast cycle is 119905

119887

If 119905119887is small then the channel will be occupied by a large

number of broadcast packets thus influencing the normaldata transmission However large 119905

119887will lose the predic-

tion value due to the frequent changes in actual situationTherefore 119905

119887should be set properly such as 10 seconds A

broadcast cycle can be divided intomultiple correction cycles

The node in a correction period measures their movementstate While finding the coordinatesrsquo different Δ119904 between thecurrent forecast coordinate at 119905 + 119905

119891and the last broadcast

coordinates surpasses it indicates that the vehiclersquos drivingcondition changes If Δ119904 is greater than a certain value thenode broadcasts the position again to correct the predictposition of itself in neighbor nodesrsquo state table thus to ensurethe prediction accuracy Suppose the correct period is 119905

119903

Meanwhile if 119902 receives the position broadcast of thenearby nodes it maintains an adjacent link (see Table 1) torecord node information that meets with 119902 It can be seenfrom the table that 119902

2measures its position and velocity at

131112101584036 and broadcasts 1199021receives the position broadcast

If11986311990211199022

(119905) le 119877 then it can be predicted that at 119905 + 119905119891 1199021and

1199022will keepmeeting If 119902

2is not in the table 119902

1adds the infor-

mation of 1199022to the table and sets 119902

2to be active If 119902

2is already

in the table update the information of 1199022 When 119902

1receives

the correction broadcast of 1199022 the position information of 119902

2

also needs updating If it can be predicted that 1199021and 1199023will

not meet at 119905 + 119905119891 set 119902

3to be inactive As to the inactive

node in the table if no broadcasts are received in more thanone broadcast cycle then delete the entry of this inactivenode Each time the passenger calls a taxi several links will beproduced If 119902

1and 1199023are neighbors and are both in one link

then they set up link ID in the entry for each other in theirown table Link ID is a large number that is randomly gener-ated It can be assumed that it is unique in a limited region

When 1199021receives the broadcast of neighbors at time 119905 it

will predict coordinates of itself and neighbor nodes at 119905 + 119905119891

respectively If the two cars can keep communication at thattime (such as 119902

2) the communication is effective Therefore

1199021stores the information of 119902

2in the table otherwise discards

it (such as the 1199023)

In order to provide the position information and routingof not-taken taxis the hop distance should be introducedwhen 119902 node is broadcasting message (including positionand correction broadcast) Periodically 119902

119904sets 119867

119902119904

to 0 andsends broadcastThe 119902

119904discards any broadcast information it

received without processing The 119902 sets119867119902value toinfin when

no neighbor nodes can reach 119902119904node When 119902

1receives the

broadcast of 1199022with the active state if 119867

1199022

+ 1 lt 1198671199021

1199021

modifies the1198671199021

value to1198671199022

+ 1Once 119867

1199021

changes 1199021will spread to notify neighbor

nodes to be updated by periodical breakfast But each cyclecan only update 1 hop on the link If 119867

11990211199022

= 119899 it needs 119899cycle to update119867

1199022

In order to improve the broadcast speed of119867 the sending

phase of each cycle is divided into two time slices The nodeof119867 changes but no broadcast will be broadcasted at the firsttime slice If the 119867 value has no change after last broadcastthe node broadcasts in the second time slice Thus the valueof119867may spread 2 hops in a cycle For the length of link willbe limited in 3-4 hops in the actual system two cycles cancomplete the information disclosure of not-taken taxis by theimproved broadcast speed

22 Links Setting and Handshake When 119901 launches the callit needs to find suitable not-taken taxis 119902

119904as soon as possible

and make an appointment In this process the following



Neighbor 119867119902119899119902119904


1199022

3 120213476E30321768N 119889

1199022

182378627 094 131112101584036 Active

1199023

5 120213484E30321775N 119889

1199023

452766732 083 131037101584034 Inactive

p

qa(H = 2)

qb(H = 5)

qc(H = 3)

qd(H = 1)

(a)

qs

q998400a(Dp1q119904= 200m)

q998400b(Dp3q119904= 300m)

(b)
















p qc qc qs








119904



119902= 119867119902119886



119902= 0 that



119904






= 0 1198671199021

= 1 1198671199022

= 2 and1198671199023



1will


1199021












119891and






1198801199021199021015840 (119905 119905 + 119905

119891) =

integration(119905 119905 + 119905

119891) (1)




2) = active119867

1199022

+

1 lt 1198671199021

and1198801199021199021015840(119905 119905 + 119905


1199021



























4 then the timer

2will be launched






119867new = 119867If (no-load)119867new = 0


If (119905119888minus 119905ge119905119891)


119888)

119905 = 119905119888

119878 = 1198781015840



119905 = 119905119888

119878 = 1198781015840


119902


119891)



If (119905119888minus 119905119902ge 2119905119891)

Remove q from table

Update H



119887





Case1198721


breakCase119872

3


Count = 1send119872




119902= 0

else





119902= 119867 minus 1

Case1198724



119902= 119867 + 1



Default




1)

Set Timer1()





Set timer2


Case1198722

Add q to queueBreak

Case1198724

Cancel Timer2Break

Case119872119890


Default



request again











119863





74

76

78

80

82Su

cces

sful r

ate (

)


04

06

08

1

12

14

Link

bro

ken

ratio

()








2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh


20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Neighbor 119867119902119899119902119904


1199022

3 120213476E30321768N 119889

1199022

182378627 094 131112101584036 Active

1199023

5 120213484E30321775N 119889

1199023

452766732 083 131037101584034 Inactive

p

qa(H = 2)

qb(H = 5)

qc(H = 3)

qd(H = 1)

(a)

qs

q998400a(Dp1q119904= 200m)

q998400b(Dp3q119904= 300m)

(b)
















p qc qc qs








119904



119902= 119867119902119886



119902= 0 that



119904






= 0 1198671199021

= 1 1198671199022

= 2 and1198671199023



1will


1199021












119891and






1198801199021199021015840 (119905 119905 + 119905

119891) =

integration(119905 119905 + 119905

119891) (1)




2) = active119867

1199022

+

1 lt 1198671199021

and1198801199021199021015840(119905 119905 + 119905


1199021



























4 then the timer

2will be launched






119867new = 119867If (no-load)119867new = 0


If (119905119888minus 119905ge119905119891)


119888)

119905 = 119905119888

119878 = 1198781015840



119905 = 119905119888

119878 = 1198781015840


119902


119891)



If (119905119888minus 119905119902ge 2119905119891)

Remove q from table

Update H



119887





Case1198721


breakCase119872

3


Count = 1send119872




119902= 0

else





119902= 119867 minus 1

Case1198724



119902= 119867 + 1



Default




1)

Set Timer1()





Set timer2


Case1198722

Add q to queueBreak

Case1198724

Cancel Timer2Break

Case119872119890


Default



request again











119863





74

76

78

80

82Su

cces

sful r

ate (

)


04

06

08

1

12

14

Link

bro

ken

ratio

()








2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh


20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











119902= 119867119902119886



119902= 0 that



119904






= 0 1198671199021

= 1 1198671199022

= 2 and1198671199023



1will


1199021












119891and






1198801199021199021015840 (119905 119905 + 119905

119891) =

integration(119905 119905 + 119905

119891) (1)




2) = active119867

1199022

+

1 lt 1198671199021

and1198801199021199021015840(119905 119905 + 119905


1199021



























4 then the timer

2will be launched






119867new = 119867If (no-load)119867new = 0


If (119905119888minus 119905ge119905119891)


119888)

119905 = 119905119888

119878 = 1198781015840



119905 = 119905119888

119878 = 1198781015840


119902


119891)



If (119905119888minus 119905119902ge 2119905119891)

Remove q from table

Update H



119887





Case1198721


breakCase119872

3


Count = 1send119872




119902= 0

else





119902= 119867 minus 1

Case1198724



119902= 119867 + 1



Default




1)

Set Timer1()





Set timer2


Case1198722

Add q to queueBreak

Case1198724

Cancel Timer2Break

Case119872119890


Default



request again











119863





74

76

78

80

82Su

cces

sful r

ate (

)


04

06

08

1

12

14

Link

bro

ken

ratio

()








2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh


20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












119867new = 119867If (no-load)119867new = 0


If (119905119888minus 119905ge119905119891)


119888)

119905 = 119905119888

119878 = 1198781015840



119905 = 119905119888

119878 = 1198781015840


119902


119891)



If (119905119888minus 119905119902ge 2119905119891)

Remove q from table

Update H



119887





Case1198721


breakCase119872

3


Count = 1send119872




119902= 0

else





119902= 119867 minus 1

Case1198724



119902= 119867 + 1



Default




1)

Set Timer1()





Set timer2


Case1198722

Add q to queueBreak

Case1198724

Cancel Timer2Break

Case119872119890


Default



request again











119863





74

76

78

80

82Su

cces

sful r

ate (

)


04

06

08

1

12

14

Link

bro

ken

ratio

()








2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh


20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












119902= 119867 minus 1

Case1198724



119902= 119867 + 1



Default




1)

Set Timer1()





Set timer2


Case1198722

Add q to queueBreak

Case1198724

Cancel Timer2Break

Case119872119890


Default



request again











119863





74

76

78

80

82Su

cces

sful r

ate (

)


04

06

08

1

12

14

Link

bro

ken

ratio

()








2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh


20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










74

76

78

80

82Su

cces

sful r

ate (

)


04

06

08

1

12

14

Link

bro

ken

ratio

()








2 4 6 8 10

1900

1950

2000

2050

Ove

rhea

d (p

acke

t)

Time (min)

40kmh60kmh80kmh


20

40

60

80

100

Succ

essfu

l rat

e (

)

1 2 3 4 5 60

2

4

6

8

Link

bro

ken

ratio

()













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













find 119879119863


119863



119863

200m 148 785 498 955300m 443 912 784 942500m 611 941 873 946




5 Conclusion







Acknowledgment


References






















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation




















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article A Lightweight Neighbor-Info-Based Routing …downloads.hindawi.com/journals/tswj/2014/601913.pdf · 2019. 7. 31. · Research Article A Lightweight Neighbor-Info-Based