research article the communication solution for lte system

Research ArticleThe Communication Solution for LTE System underRadar Interference Circumstance

Hang Zheng Yunjie Li and Yunpeng Zhu

School of Information and Electronics Beijing Institute of Technology Beijing 100081 China

Correspondence should be addressed to Yunjie Li liyunjiebiteducn

Received 18 November 2014 Accepted 19 January 2015

Academic Editor Nima Chamanara

Copyright copy 2015 Hang Zheng 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

The interferences of radar and communication system coexistent environment are analyzed in this paper and an attractive detectionmechanism of the radar video signal and proportional fair scheduling algorithm based on channel sensing are proposed to realizethe communication by using radar radiant intermissions And the simulation is designed based on the proposed model to test thisplanThe simulated results show that the packet scheduling algorithm is an excellent candidate for the communication solution forLTE system under radar radiant intermissions

1 Introduction

The Third Generation Partnership Project (3GPP) haslaunched Long Term Evolution (LTE) of next generationmobile communications on the frequency bands of 1710ndash1885MHz 2300ndash2400MHz and 2500ndash2690MHz based onthe number 223 resolution of the World Radiocommuni-cation Conference in 2007 as discussed elsewhere [1 2]The development of 3GPP LTE has witnessed explosivegrowth driven by the wireless communication system Inaddition version R9 of LTE has been released in March2010 which forms executive standard of LTE At present theChinese Mobile Communication Corporation (CMCC) hasdeveloped theTimeDivision LongTermEvolution (TD-LTE)system which has been tested and utilized in many citiesacross the whole country

However the shortage of spectrum resources becomesan increasingly serious problem for LTE system especiallyin high-frequency bands that is 2500ndash2690MHz The LTEsystem with working frequency band of 2500ndash2690MHzhas interference problems with high power radars in theadjacent frequency band such as the S-waveband weatherradars and air traffic-control radars When the frequencyspace between radar and LTE system is not large enoughthe radar signal power is so high that the band-pass filter

could not filter out the radar dominant frequency signal toan acceptable degree in the radar pulse signal duration Andthe residuals signal with high amplitude will still interferewith the communication signals Meanwhile the radar out-of-band spurious signal falls into filterrsquos pass-band and itwill not be attenuated by the filter thus causing interferenceWhen the radar works at the same frequency band of LTEsystem the radar dominant frequency signals could easilyburn through the receiver

The interferences mentioned above will affect the per-formance of LTE system and restrict its promotion as wellas the further utilization of these new assigned frequencybandsTherefore this paper applies the principle of cognitiveradio (CR) to study the interference between radar and LTEsystem as discussed elsewhere [3ndash5] and it comes up with aprecise detection mechanism of radar video signal to realizespectrum sensing as well as a proportional fair schedulingalgorithm based on channel sensing for spectrum allocationIn the past papers researchers usually suggested a protectiondistance between radar and communication system to ensurea ldquocleanrdquo electromagnetism reserve In this paper when LTEsystem is not so far away from radar LTE system can establishcommunication in radar radiant intermittent periods sothey can work compatibly with slightly lower data rate andapproximate block error rate

Hindawi Publishing CorporationInternational Journal of Antennas and PropagationVolume 2015 Article ID 849695 8 pageshttpdxdoiorg1011552015849695

2 International Journal of Antennas and Propagation

Cell B

Cell A

Sector 1

Sector 2

Sector 3

Cell C

Scan beam scanning into cell B

Scan beam scanning out

of cell B

Main beam and near zone minor lobe of radar azimuth

scan

1205791

1205792

Figure 1 Radar and LTE coexistent environment

Table 1Main technical parameters of weather radar in S-waveband

Parameters ValueWorking frequency 2720 plusmn 1MHzPeak power 650KwPulse width (120591) 1 120583s or 4 120583sBeam width 1∘

Antenna gain 44 dBAntenna near zone minor lobe minus29 dB (from 2∘ to 10∘)Antenna far zone minor lobe minus40 dB (over 10∘)Receiver sensitivity minus113 dBmIntermediate frequency 30MHzPulse repetition time (PRT) 300Hz 450Hz 600HzPulse intermittent period (PJ) PJ = PRT minus 120591Polarization mode Horizontal polarization

2 Materials and Methods

21 Materials

211 Basic Characteristics of Target System When radarand LTE cells are located as in Figure 1 the main beamand near zone minor lobe of radar will interfere with thereceivers of LTE system in varying degreeThere are two radarintermissions that can be utilized the first one is the pulseintermission when radar beam passes over the cell B area andthe second one is scanning intermission when radar beamscans out of cell B area

By requiring from meteorological department maintechnical parameters of weather radar can be shown inTable 1 while the parameters of LTE base stations (eNodeBs)and user equipment (UE) can be listed in Tables 2 3 bylooking up related literatures and actual measurements asdiscussed in [6]These parameters can be used to compute thestrength of signal in order to judge interference conditionor calculate intermissions for communication or be used forsimulation

Table 2 Main technical parameters of LTE base station (eNodeB)

Parameters ValueWorking frequency 2500ndash2690MHzPeak power 40KwAntenna gain 165 dBIntersite distance 1000 metersAntenna near zone upper minor lobe minus16 dB (from 0∘ to 60∘)Antenna far zone upper minor lobe minus23 dB (over 60∘)Receiver sensitivity minus117 dBm

Horizontal beam width Consists of multiple 60∘beams and covers 360∘

Table 3 Main technical parameters of user equipment (UE)

Parameters ValueWorking frequency 2500ndash2690MHzPeak power 2wBeam mode OmnidirectionalAntenna gain 0 dBReceiver sensitivity minus110 dBm

212 Interference Analysis on Radar and LTE CoexistentEnvironment According to Friis transmission formulathe receiving power can be calculated by the followingformula which reflects interference signal strength and ithelps in judging whether a certain system is interfered ornot

119875119903=

119875119905119866119905

41205871198772

119866119905119891

1198661199031205822

4120587119866119903119891

1

119871119905119871119903119871119889

1

119871119895

1

119876119905119876119895

(1)

For evaluating whether a LTE system such as eNodeBs orUE is interfered with weather radar it needs to calculatethe radar antenna power density in eNodeBs at first that is11987511990511986611990541205871198772

119866119905119891 where subscript 119905 represents radar system 119875

119905

is the antenna power 119866119905is antenna gain 119866

119905119891means antenna

minor lobe and 119877 represents distance between radar andLTE system Then the signal power received by the LTEsystem can be computed by 119875

1199051198661199051198661199031205822

(4120587119877)2

119866119905119891119866119903119891 where

subscript 119903 means LTE system 119866119903is the antenna gain 119866

119903119891

is the antenna minor lobe and 120582 means radar wavelengthIn addition it needs considering of different transmissionlosses 119871

119905119871119903119871119889119871119895 where 119871

119905and 119871

119903are antenna feeder losses

119871119889

represents maximum multipath signal of radar and119871119895means polarization mismatching loss of the coexistent

system Finally it needs computing the different spurioussuppressions 119876

119905119876119895 where 119876

119905is radar spurious suppression

at the frequency of LTE system and 119876119895is the out-of-band

and filter suppression of LTE system In this way the powerof radar interference signal received by LTE system can becalculated and the interference conditions can be defined bycomparing with receiver sensitivity

For instance when the LTE system is working at2670MHz weather radar works at 2720MHz and Tables 4 5

International Journal of Antennas and Propagation 3

Table 4 Transmitter parameters in meteorological radars (domi-nant frequency interference)

Parameters ValuePeak power (119875

119905

) 881 dBmGain (119866

119905

) 44 dBMinor lobe level (119866

119905119891

) 0 dBFrequency band factor 1205822 minus191 dBConstant (4120587)2 minus2198 dBFeeder loss (119871

119905

) minus3 dBMaximum multipath signal (119871

119889

) 0 dBDistance 1198772 (300m) minus4954 dBSpurious suppression in LTErsquos working frequency (119876

119905

) 0 dB

Table 5 Receiver parameters in LTE base station

Parameters ValueAntenna gain (119866

119903


119903119891

) 0 dBFeeder loss (119871

119903

) minus15 dBPolarization loss (119871

119895

) minus15 dBOut-of-band spurious and filter suppression (119876

119895

) minus150 dBReceiver sensitivity minus117 dBm

list other related parametersThe interference power receivedby LTE system can be obtained in decibel by

119875119903=

119875119905119866119905

(4120587)2

1198772

119866119905119891

1198661199031205822

119866119903119891

1

119871119905119871119903119871119889

1

119871119895

1

119876119905119876119895

= 881 + 44 + 165 minus 191 minus 2198 minus 4954 minus 0

minus 0 minus 3 minus 15 minus 15 minus 150

= minus9802 dBm

(2)

which is higher than the receiver sensitivity of eNodeB withvalue of minus117 dBm it can foresee that the eNodeB is interferedby the main beam of weather radar within 300 meters away

When considering other effects including near or far zoneminor lobe multipath echo signal and different distances itcan be concluded that when the weather radar is within 30 to2500 meters away from the LTE base station the LTE systemis interfered by radar while interferences from LTE system toradar can be ignored

The Communication Solution in the Coexistent Systems Afteranalyzing interference condition the radar pulse intermis-sions need to be found for communication therefore aprecise detectionmechanismof radar video signal is designedto realize the spectrum sensing and a channel-sensing-basedLTE packet scheduling algorithm is proposed to approachspectrum access

213 Sensing of Radar Radiant Environment The technicalparameters of weather radar remain stationary and simplewhich also can be detected previously and it is required fora cognitive system (LTE system) to detect the authorized

users (weather radars) precisely in real time Therefore thispaper proposes an attractive detection mechanism of theradar video signal based on the matched filter in frequencydomain which can be divided into three parts as shown inFigure 2

(i) RF Pilot Frequency Matching Channel The first part isthe RF pilot frequency matching channel This channel isimported with the high-frequency signal of the weatherradar and the signal passes through the band-pass filter RFamplifier mixer and analog to digital conversion in turn tobe transformed to digital IF signal

(ii)MatchingDetection in FrequencyDomainThesecond partis thematching detection in frequency domainThematchingdetection part is made up of computation modules such asFFT square and threshold comparison

This part uses spectral transform and computation todetect the radar signal and obtain the frequency and energyof the radar signal as well as the raw detection of pulserepetition period Because the energy of spectrum 119864

119865119863with

central frequency 119891119888and bandwidth 119908 is

119864119865119863

=119891119904

2120587119873

1198962

sum

119896=1198961

|119909 (119896)|2

(3)

where 119873 is the FFT length 119909(119896) represents digital radarsignal 119891

119904means sample rate and 119896

2and 119896

1are the upper

and lower bounds of frequency points After comparingwith (3) and detection threshold 120582 which is detected inthe engineering environment the proposed mechanism canascertain whether there is authorized signal received incognitive system receiver by formula (4) and detect thefrequency and energy of the authorized signal and makedetection on pulse repetition period

119864119865119863

le 1205821 (no authorized signal)

119864119865119863

gt 1205821 (1 120583s authorized signal)

119864119865119863


(4)

(iii) Precise Video Signal DetectionThefinal part is the precisevideo signal detection In this part the processed radarsignal passes through envelope detection amplifier thresholddetection and computation modules in turn As long as thematching detection part detects radar signal the mechanismcan immediately obtain the measurement of pulse start time119879119886119894 pulse end time 119879

119887119894 pulse width 120591 = 119879

119887119894minus 119879119886119894 and pulse

amplitude 119875119886 These parameters are used to ascertain which

LTE scheduling period is interferedAnd then the mechanism can acquire the repetition

period of pulse signal by 119879 = 119879119886(119894+1)

minus 119879119886119894and the antenna

scanning period 119876 = 119879119864max+1

minus 119879119864max

which is the intermis-sion between the two maximum values of pulse amplitudesmeasured by statistics Finally the scanning intermission isgot as 119876

119895119909= 119876 minus (119879

119886119894+ 120591 minus 119879

1198861)

This sensing mechanism starts sensing when the LTEeNodeB begins working After the sensing mechanism has


Band-passfilter

LTE base station antenna

Mixer

FFT Integrationmodule

Calculationmodule

ADconversion

Video amplifier

Detection threshold

Timer

Localoscillator

Envelope detection

Thresholdcomparator

RFamplifier

Ei le 1205821 (no radar pulse signal)

Ei gt 1205821 (1120583s radar signal exists)


T = TE119894+1 minus TE119894 (raw detection on

fc (central frequency of detection)Tai pulse start timeTbi pulse finish time

T pulse repeat cycle

repeat scan period)

Tjx pulse intermission ( (Tjx = T minus 120591

120591 pulse width (120591 = Tbi minus Tai)

| middot |2

Pa pulse amplitude

Figure 2 Compositions of precise radar detection mechanism

detected and calculated radar pulse start time 119879119886119894 the sched-

uler of eNodeB system will use the detected parameters forscheduling Although radar signal changes within a periodlength of severalmicroseconds (120583s) the radar radiant sensingscheme should operate precisely to catch changes whichmay lead to high time consumption However the weatherradar does not change its working parameters frequentlyTherefore when sensing scheme has detected and known allparameters mentioned above the eNodeB system can usethese ldquofixedrdquo parameters for a long period until the sensingscheme finds the changes in parameters In this long periodthe sensing scheme focuses more on validating interferedperiods for eNodeBrsquos scheduler comparing with the simpleprecise detection Hence the scheduler uses predetectedparameters to compute which transmission time interval(TTI) is interfered and skips those TTIs while sensingscheme detects and tells the latest pulse start time to theeNodeB system to checkwhether it skips interference in rightTTIs In this way tiny time consumption is permitted andsensing scheme can tell pulse start time to the eNodeB systemimmediately for validation which is before completing allother parameters to find out changes and do regularly precisedetection at set intervals for example half an hour

214 LTE Packet Scheduling Algorithm for Spectrum AccessOrthogonal frequency division multiple access (OFDMA)system is the downlink multiple access technology of LTEsystem and it uses packet scheduling mechanism to allocatesubchannels which can be seen as resource blocks (RBs) todifferent users There are three common packet schedulingalgorithms as discussed elsewhere [7] and proportional fair(PF) scheduling algorithm is chosen in this work because itmakes a compromise between system throughput and userfairness

(i) Proportional Fair Scheduling Algorithm PF schedulingalgorithm means every user can obtain equal schedulingopportunities as discussed elsewhere [8 9] In each schedul-ing period each user will be assigned a correspondingpriority by userrsquos instantaneous speed 119903

119894(119899) divided by average

speed 119877119894(119899) and each subchannel will choose the user with

highest priority to transmit data Hence if there are 119870 userswho require for transmitting data at scheduling period 119899 thechosen user will be

119894lowast

= argmax1le119894le119870

119903119894(119899)

119877119894(119899)

(5)

After one scheduling period the average rates of users will beupdated as

119877119894(119899 + 1) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(6)

where 119879119888is a time window parameter

(ii) Proportional Fair Scheduling Algorithm Based on ChannelSensingBecause working frequency of the LTE system is nearradarrsquos operating frequency band when the radar pulse signaloccurs in a certain scheduling period that is transmissiontime interval (TTI) all subchannels in the system will beinterfered with radar radiant pulse signal At this time allchannel qualities are not good enough for users to com-municate Hence this project adopts channel sensing factor119860 to proportional fair scheduling algorithm and makes thechannel qualities of all TTIs interferedwith pulse signals zeroAnd then the scheduler will not assign that channel to thatuser Because all channels are interfered the scheduler willstop working for the TTI and recalculate usersrsquo priority forscheduling in the next TTIThen PF algorithmwill be revisedas

119894lowast

= arg max 119875119894(119899) = arg max

119903119894(119899) lowast 119860

119877119894(119899)

(7)


Displayinterfacemodule

Configurationmodule

Simulationprocesscontrolmodule

module

Networklayout

module

Antennamodule

Usermodule

Transmissionenvironment

module

Resourcesscheduling

module

Link measurementand self-adaptivestrategy module

Radar pulse signalinterference

Figure 3 Module architecture

where

119877119894(119899) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899 minus 1) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(8)

119860 =

0 119899 = 1198990+

10038161003816100381610038161003816100381610038161003816

1198791198861minus 1198790+119886 lowast 119879

1000

10038161003816100381610038161003816100381610038161003816

+ 119887 lowast 1000 lowast 119876

1 other TTI(9)

119886 isin [0

100381610038161003816100381610038161003816100381610038161003816

(120579360∘

) lowast 106

lowast 119876

119879

100381610038161003816100381610038161003816100381610038161003816

] 119886 isin 119885 119887 isin 119885 (10)

where 1198790is the start time of the scheduling period 119899

0when

radar pulse signal occurs for the first time and 1198791198861is the start

time of the first detected pulse signal when radar antennascanning into sector 119861 then 119879

1198861minus 1198790is used to find when

radar pulse occurs in the TTI119879 is the pulse repetition period119886 represents the pulse number detected by eNodeB withinone antenna scan cycle 119876 is the antenna scan cycle while120579 is the antenna scan angle over sector 119861 and | sdot | is doingdecimals to round down numbers Therefore 119886 lowast 1198791000

represents pulse repetition time and |1198791198861minus 1198790+ 119886 lowast 1198791000|

is used to compute the TTI number when radar pulses occurBesides 119887 represents the antenna scan times and 119887lowast1000lowast119876is computing the time of different antenna scan cycles Inaddition the unit of 119879 119879

1198861is microsecond (120583s) the unit of

119876 is second and the duration of one TTI is 1ms which isalso the length of scheduling period

3 Results and Discussion

31 System Level Simulation Platform of Radar and LTECoexistent System For the system level simulation platformit mainly concentrates on problems of scheduling and inter-ference management The platform is set up by Matlab withten modules which can be seen from Figure 3 The main

body of the simulation platform includes the simulationprocess control module the configuration module the radarpulse signal interferencemodule the network layoutmoduleand the display interface module while the transmissionenvironment module the antenna module and the usermodule are the submodules of the network layout moduleIn addition the link measurement and self-adaptive strat-egy module provides channel conditions for the resourcesscheduling module which belongs to the user module Thesimulation mainly concentrates on three modules the firstone is the radar pulse signal interference module to produceinterference the second one is the user module for detectinginterference and the third one is the resources schedulingmodule to allocate RBs

Data rate and block error ratio (BLER) are used asevaluation metrics for this simulation platform Data rateis the transmitted data flow per second while BLER is theratio of the number of received error blocks and that of totalreceived blocks

And the simulation parameters configuration can be seenin Table 6 where some parameters are chosen as discussedelsewhere [10ndash13] The users are dropped randomly andimmovably in the entire LTE cell while the traffic model isFull-Buffer thus simplifying the simulation model

32 Simulation Results and Analysis

321 Channel Allocation When 10 pieces of UE are assignedto each sector randomly thenRBs allocation can be seen fromFigure 4 When the number of RBs assigned to each userdecreases to 0 there are special blue broken lines occupyingall 25 RBs which occur in every three or four TTIs It is avirtual UE piece 0 which represents the scheduler of eNodeBThe RBs assigned to UE piece 0 represent that these RBs areinterfered by radar pulse signal at that TTI and they are notassigned to any real user due to their poor channel quality butreserved by the scheduler itself

When the first pulse signal starts at 23211ms that isTTI 23 if the scan period of radar antenna is 1 s the scanangle of the radar antenna over the cell area is 5 degrees


15 20 25 30 35 400

5

10

15

20

25

TTI number

Ass

igne

d RB

sAssigned RBs eNodeB 5 sector 1 stream 1 TTIs 15ndash40

UE piece 0UE piece 1UE piece 2UE piece 3UE piece 4


(a) Radar pulse signal starts at TTI 23

80 82 84 86 88 90 92 94 96 98 1000

5

10

15

20

25

TTI number

Ass

igne

d RB

s

Assigned RBs eNodeB 5 sector 1 stream 1 TTIs 80ndash100



(b) RBs allocation in TTI 80 to TTI 100

140 145 150 155 160 165 1700

5

10

15

20

25

TTI number

Ass

igne

d RB

s

UE piece 0UE piece 1UE piece 2UE piece 3UE piece 4UE piece 5



(c) Radar pulse signal ends at TTI 159

Figure 4 Channel allocation with radar pulse signal interference

then all pulse start times and their corresponding TTIs canbe calculated by formula (9) and the results are in accordancewith the time when UE piece 0 occurs as shown in Figure 4Hence this simulation platform can certainly keep away fromthe interfered TTIs and then communicate in other TTIsby using precisely detected parameters of radar pulse signalwhen radar pulse signals occur

322 Data Rate By allocating a different number of usersin each sector such as 5 10 15 20 25 30 pieces of UE thisplatform can obtain the data rate of the entire cell with orwithout radar interference as shown in Figure 5

When 5 users are allocated in each sector the averagedata rate of interfered cell is 107865Mbps while that of cellwithout interference is 11023Mbps Hence the attenuation ofaverage data rate is 21455 The attenuation trend increases

with the increase of UE pieces number and is stable to 7which is within the acceptable range as shown in Figure 6Hence the simulation results show that the proposed com-munication scheme for the radar and LTE coexistent systemis effective

In addition the above data is mainly obtained whenradar antenna beam scans over cell B area as shown inFigure 3 which occupies only a small part of the whole radarantenna scan period After considering the periods whenradar antenna scans over the other directions the data rate ofcell B is not interfered Therefore when comparing a normalLTE system (which is not adjacent to a radar) with a LTEsystem that is affected by radar and that used the presentedsolution the data rate of the first and the second case shouldbe the same And then the data rate attenuation ratio shoulddecrease a lot in the whole radar antenna scan period


12

5 10 15 20 25 306

8

10

14

16

18Data rate comparison

Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629

w-interferencewo-interference

Figure 5 Data rate comparison

5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()

Data rate attenuation ratio

X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119

Figure 6 Data rate attenuation ration

323 BLER By allocating a different number of users in eachsector such as 5 to 30 pieces of UE the BLER variations canbe seen from Figure 7

When 5 pieces of UE are allocated in each sector BLER ofinterfered cell is 00467 while that of cell without interferenceis 00482 Hence BLER gain is 33195 The trend of averageBLER gain decreases with increase of UE pieces number andfinally it is stable within 1 range comparingwith BLER valueof cell without interference

In general the BLER of interfered cell is floating slightlyaround that of cell without interference Hence by sensing ofradar pulse signal this communication scheme can make theLTE system keep away from TTIs when radar pulse signalsoccur And then the LTE system can communicate at otherTTIs which will decrease radar influences on BLER

5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2

Figure 7 BLER comparison

Table 6 Simulation parameters configuration

Parameters Value

Cellular layout Hexagonal grid 1 cell site 3 sectorsper site

Cell radius 250mTraffic model Full-Buffer [10]Macroscopic path lossmodel TS 36942 [11]

Fast fading PedB modelRadar pulse signalrepetition period 3333ms

UE distribution Users dropped randomly in entirecell

UE speeds 0Bandwidth 5MHzSimulation length 200 TTIsTTI length 1msChannel model Typical urban (TU) [12]

4 Conclusions

This paper applies the principle of cognitive radio to inter-disciplinary knowledge of radar and LTE system And thena communication scheme is proposed which utilizes radarradiant intermittent periods to realize communication inradar and communication coexistent system The proposedscheme has been analyzed and the analysis proves thatit can keep away from interference of radar pulse signaland communicate in radar pulse intermission according toprecisely detected signal parameters Simulation results showthat the data rate attenuation is stable to 7 while BLERgain is stable within 1 which proves the effectiveness of thecommunication scheme


Conflict of Interests

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

Acknowledgments

In this research my knowledge of radar and LTE systemhas improved greatly and I have learnt many useful learningmethods and thinking perspectives to solve problems Allthanks are due to our tutors Yunjie Li and Zhenglei Huangand other friends who helped us a lot and encouraged uswhen we had problems

References

[1] S Sesia I Toufik and M Baker LTEmdashThe UMTS Long TermEvolution FromTheory to Practice Including Release 10 for LTE-Advanced JohnWiley amp Sons NewYork NY USA 2nd edition2011

[2] ldquoIEEE standard for safety levels with respect to human exposureto radio frequency electromagnetic fields 3 kHz to 300GHzrdquoIEEE Standard C951 2005

[3] J Mitola III and G Q Maguire Jr ldquoCognitive radio makingsoftware radios more personalrdquo IEEE Personal Communica-tions vol 6 no 4 pp 13ndash18 1999

[4] J Mitola Cognitive radio an integrated agent architecture forsoftware defined radios [PhD dissertation] Royal Institute ofTechnology (KTH) Stockholm Sweden 2000

[5] S Haykin ldquoCognitive radio brain-empowered wireless com-municationsrdquo IEEE Journal on Selected Areas in Communica-tions vol 23 no 2 pp 201ndash220 2005

[6] F J Harris C Dick and M Rice ldquoDigital receivers andtransmitters using polyphase filter banks for wireless com-municationsrdquo IEEE Transactions on Microwave Theory andTechniques vol 51 no 4 pp 1395ndash1412 2003

[7] 3GPP TS 36814 V900 Evolved Universal Terrestrial RadioAccess (E-UTRA) Further advancements for E-UTRAPhysicallayers aspects Dec 2009

[8] C Suh S Park andYCho ldquoEfficient algorithm for proportionalfairness scheduling inmulticast OFDM systemsrdquo in Proceedingsof the IEEE 61st Vehicular Technology Conference (VTC rsquo05) vol3 pp 1880ndash1884 Stockholm Sweden June 2005

[9] H Kim K Kim Y Han and S Yun ldquoA proportional fairscheduling for multicarrier transmission systemsrdquo in Proceed-ings of the IEEE 60thVehicular TechnologyConference (VTC-Fallrsquo04) vol 1 pp 409ndash413 September 2004

[10] R love R Kuchibhotla A Ghosh et al ldquoDownlink controlchannel design for 3GPP LTErdquo pp 813ndash818 IEEE Las VegasNev USA March-April 2008

[11] 3GPP TR 36942 V810 ldquoTechnical Specification Group RadioAccess Network EvolvedUniversal Terrestrial Radio Access (E-UTRA) Radio Frequency (RF) system scenariosrdquo September2009

[12] H Asplund K Larsson and P Okvist ldquoHow typical is thelsquotypical urbanrsquo channel modelrdquo in Proceedings of the IEEE 67thVehicular Technology Conference-Spring (VTC rsquo08) pp 340ndash343 May 2008

[13] N Arsalane M Mouhamadou C Decroze D CarsenatM A Garcia-Fernandez and T Monediere ldquo3GPP channelmodel emulation with analysis of MIMO-LTE performances in

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Cell B

Cell A

Sector 1

Sector 2

Sector 3

Cell C

Scan beam scanning into cell B

Scan beam scanning out

of cell B

Main beam and near zone minor lobe of radar azimuth

scan

1205791

1205792

Figure 1 Radar and LTE coexistent environment

Table 1Main technical parameters of weather radar in S-waveband

Parameters ValueWorking frequency 2720 plusmn 1MHzPeak power 650KwPulse width (120591) 1 120583s or 4 120583sBeam width 1∘

Antenna gain 44 dBAntenna near zone minor lobe minus29 dB (from 2∘ to 10∘)Antenna far zone minor lobe minus40 dB (over 10∘)Receiver sensitivity minus113 dBmIntermediate frequency 30MHzPulse repetition time (PRT) 300Hz 450Hz 600HzPulse intermittent period (PJ) PJ = PRT minus 120591Polarization mode Horizontal polarization

2 Materials and Methods

21 Materials

211 Basic Characteristics of Target System When radarand LTE cells are located as in Figure 1 the main beamand near zone minor lobe of radar will interfere with thereceivers of LTE system in varying degreeThere are two radarintermissions that can be utilized the first one is the pulseintermission when radar beam passes over the cell B area andthe second one is scanning intermission when radar beamscans out of cell B area

By requiring from meteorological department maintechnical parameters of weather radar can be shown inTable 1 while the parameters of LTE base stations (eNodeBs)and user equipment (UE) can be listed in Tables 2 3 bylooking up related literatures and actual measurements asdiscussed in [6]These parameters can be used to compute thestrength of signal in order to judge interference conditionor calculate intermissions for communication or be used forsimulation

Table 2 Main technical parameters of LTE base station (eNodeB)

Parameters ValueWorking frequency 2500ndash2690MHzPeak power 40KwAntenna gain 165 dBIntersite distance 1000 metersAntenna near zone upper minor lobe minus16 dB (from 0∘ to 60∘)Antenna far zone upper minor lobe minus23 dB (over 60∘)Receiver sensitivity minus117 dBm

Horizontal beam width Consists of multiple 60∘beams and covers 360∘

Table 3 Main technical parameters of user equipment (UE)

Parameters ValueWorking frequency 2500ndash2690MHzPeak power 2wBeam mode OmnidirectionalAntenna gain 0 dBReceiver sensitivity minus110 dBm

212 Interference Analysis on Radar and LTE CoexistentEnvironment According to Friis transmission formulathe receiving power can be calculated by the followingformula which reflects interference signal strength and ithelps in judging whether a certain system is interfered ornot

119875119903=

119875119905119866119905

41205871198772

119866119905119891

1198661199031205822

4120587119866119903119891

1

119871119905119871119903119871119889

1

119871119895

1

119876119905119876119895

(1)

For evaluating whether a LTE system such as eNodeBs orUE is interfered with weather radar it needs to calculatethe radar antenna power density in eNodeBs at first that is11987511990511986611990541205871198772

119866119905119891 where subscript 119905 represents radar system 119875

119905

is the antenna power 119866119905is antenna gain 119866

119905119891means antenna

minor lobe and 119877 represents distance between radar andLTE system Then the signal power received by the LTEsystem can be computed by 119875

1199051198661199051198661199031205822

(4120587119877)2

119866119905119891119866119903119891 where

subscript 119903 means LTE system 119866119903is the antenna gain 119866

119903119891

is the antenna minor lobe and 120582 means radar wavelengthIn addition it needs considering of different transmissionlosses 119871

119905119871119903119871119889119871119895 where 119871

119905and 119871

119903are antenna feeder losses

119871119889

represents maximum multipath signal of radar and119871119895means polarization mismatching loss of the coexistent

system Finally it needs computing the different spurioussuppressions 119876

119905119876119895 where 119876

119905is radar spurious suppression

at the frequency of LTE system and 119876119895is the out-of-band

and filter suppression of LTE system In this way the powerof radar interference signal received by LTE system can becalculated and the interference conditions can be defined bycomparing with receiver sensitivity

For instance when the LTE system is working at2670MHz weather radar works at 2720MHz and Tables 4 5




119905

) 881 dBmGain (119866

119905


119905119891


119905


119889


119905

) 0 dB



119903


119903119891


119903


119895


119895



119875119903=

119875119905119866119905

(4120587)2

1198772

119866119905119891

1198661199031205822

119866119903119891

1

119871119905119871119903119871119889

1

119871119895

1

119876119905119876119895



= minus9802 dBm

(2)









119865119863with


119864119865119863

=119891119904

2120587119873

1198962

sum

119896=1198961

|119909 (119896)|2

(3)



2and 119896

1are the upper


119864119865119863


119864119865119863


119864119865119863


(4)


119887119894 pulse width 120591 = 119879

119887119894minus 119879119886119894 and pulse






minus 119879119864max


119895119909= 119876 minus (119879

119886119894+ 120591 minus 119879

1198861)



Band-passfilter


Mixer


Calculationmodule

ADconversion

Video amplifier

Detection threshold

Timer

Localoscillator

Envelope detection

Thresholdcomparator

RFamplifier







repeat scan period)



| middot |2

Pa pulse amplitude









119894lowast


119903119894(119899)

119877119894(119899)

(5)


119877119894(119899 + 1) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(6)



119894lowast

= arg max 119875119894(119899) = arg max

119903119894(119899) lowast 119860

119877119894(119899)

(7)



Configurationmodule


module

Networklayout

module

Antennamodule

Usermodule


module

Resourcesscheduling

module




where

119877119894(119899) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899 minus 1) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(8)

119860 =

0 119899 = 1198990+

10038161003816100381610038161003816100381610038161003816

1198791198861minus 1198790+119886 lowast 119879

1000

10038161003816100381610038161003816100381610038161003816

+ 119887 lowast 1000 lowast 119876

1 other TTI(9)

119886 isin [0

100381610038161003816100381610038161003816100381610038161003816

(120579360∘

) lowast 106

lowast 119876

119879

100381610038161003816100381610038161003816100381610038161003816

] 119886 isin 119885 119887 isin 119885 (10)


0when


















15 20 25 30 35 400

5

10

15

20

25

TTI number

Ass

igne

d RB





80 82 84 86 88 90 92 94 96 98 1000

5

10

15

20

25

TTI number

Ass

igne

d RB

s





140 145 150 155 160 165 1700

5

10

15

20

25

TTI number

Ass

igne

d RB

s












12

5 10 15 20 25 306

8

10

14

16


Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629



5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()


X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119





5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2



Parameters Value






4 Conclusions





Acknowledgments


References

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












119905

) 881 dBmGain (119866

119905


119905119891


119905


119889


119905

) 0 dB



119903


119903119891


119903


119895


119895



119875119903=

119875119905119866119905

(4120587)2

1198772

119866119905119891

1198661199031205822

119866119903119891

1

119871119905119871119903119871119889

1

119871119895

1

119876119905119876119895



= minus9802 dBm

(2)









119865119863with


119864119865119863

=119891119904

2120587119873

1198962

sum

119896=1198961

|119909 (119896)|2

(3)



2and 119896

1are the upper


119864119865119863


119864119865119863


119864119865119863


(4)


119887119894 pulse width 120591 = 119879

119887119894minus 119879119886119894 and pulse






minus 119879119864max


119895119909= 119876 minus (119879

119886119894+ 120591 minus 119879

1198861)



Band-passfilter


Mixer


Calculationmodule

ADconversion

Video amplifier

Detection threshold

Timer

Localoscillator

Envelope detection

Thresholdcomparator

RFamplifier







repeat scan period)



| middot |2

Pa pulse amplitude









119894lowast


119903119894(119899)

119877119894(119899)

(5)


119877119894(119899 + 1) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(6)



119894lowast

= arg max 119875119894(119899) = arg max

119903119894(119899) lowast 119860

119877119894(119899)

(7)



Configurationmodule


module

Networklayout

module

Antennamodule

Usermodule


module

Resourcesscheduling

module




where

119877119894(119899) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899 minus 1) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(8)

119860 =

0 119899 = 1198990+

10038161003816100381610038161003816100381610038161003816

1198791198861minus 1198790+119886 lowast 119879

1000

10038161003816100381610038161003816100381610038161003816

+ 119887 lowast 1000 lowast 119876

1 other TTI(9)

119886 isin [0

100381610038161003816100381610038161003816100381610038161003816

(120579360∘

) lowast 106

lowast 119876

119879

100381610038161003816100381610038161003816100381610038161003816

] 119886 isin 119885 119887 isin 119885 (10)


0when


















15 20 25 30 35 400

5

10

15

20

25

TTI number

Ass

igne

d RB





80 82 84 86 88 90 92 94 96 98 1000

5

10

15

20

25

TTI number

Ass

igne

d RB

s





140 145 150 155 160 165 1700

5

10

15

20

25

TTI number

Ass

igne

d RB

s












12

5 10 15 20 25 306

8

10

14

16


Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629



5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()


X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119





5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2



Parameters Value






4 Conclusions





Acknowledgments


References

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Band-passfilter


Mixer


Calculationmodule

ADconversion

Video amplifier

Detection threshold

Timer

Localoscillator

Envelope detection

Thresholdcomparator

RFamplifier







repeat scan period)



| middot |2

Pa pulse amplitude









119894lowast


119903119894(119899)

119877119894(119899)

(5)


119877119894(119899 + 1) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(6)



119894lowast

= arg max 119875119894(119899) = arg max

119903119894(119899) lowast 119860

119877119894(119899)

(7)



Configurationmodule


module

Networklayout

module

Antennamodule

Usermodule


module

Resourcesscheduling

module




where

119877119894(119899) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899 minus 1) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(8)

119860 =

0 119899 = 1198990+

10038161003816100381610038161003816100381610038161003816

1198791198861minus 1198790+119886 lowast 119879

1000

10038161003816100381610038161003816100381610038161003816

+ 119887 lowast 1000 lowast 119876

1 other TTI(9)

119886 isin [0

100381610038161003816100381610038161003816100381610038161003816

(120579360∘

) lowast 106

lowast 119876

119879

100381610038161003816100381610038161003816100381610038161003816

] 119886 isin 119885 119887 isin 119885 (10)


0when


















15 20 25 30 35 400

5

10

15

20

25

TTI number

Ass

igne

d RB





80 82 84 86 88 90 92 94 96 98 1000

5

10

15

20

25

TTI number

Ass

igne

d RB

s





140 145 150 155 160 165 1700

5

10

15

20

25

TTI number

Ass

igne

d RB

s












12

5 10 15 20 25 306

8

10

14

16


Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629



5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()


X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119





5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2



Parameters Value






4 Conclusions





Acknowledgments


References

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Configurationmodule


module

Networklayout

module

Antennamodule

Usermodule


module

Resourcesscheduling

module




where

119877119894(119899) =

(1 minus1

119879119888

)119877119894(119899) +

1

119879119888

119903119894(119899 minus 1) 119894 = 119894

lowast

(1 minus1

119879119888

)119877119894(119899) 119894 = 119894

lowast

(8)

119860 =

0 119899 = 1198990+

10038161003816100381610038161003816100381610038161003816

1198791198861minus 1198790+119886 lowast 119879

1000

10038161003816100381610038161003816100381610038161003816

+ 119887 lowast 1000 lowast 119876

1 other TTI(9)

119886 isin [0

100381610038161003816100381610038161003816100381610038161003816

(120579360∘

) lowast 106

lowast 119876

119879

100381610038161003816100381610038161003816100381610038161003816

] 119886 isin 119885 119887 isin 119885 (10)


0when


















15 20 25 30 35 400

5

10

15

20

25

TTI number

Ass

igne

d RB





80 82 84 86 88 90 92 94 96 98 1000

5

10

15

20

25

TTI number

Ass

igne

d RB

s





140 145 150 155 160 165 1700

5

10

15

20

25

TTI number

Ass

igne

d RB

s












12

5 10 15 20 25 306

8

10

14

16


Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629



5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()


X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119





5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2



Parameters Value






4 Conclusions





Acknowledgments


References

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










15 20 25 30 35 400

5

10

15

20

25

TTI number

Ass

igne

d RB





80 82 84 86 88 90 92 94 96 98 1000

5

10

15

20

25

TTI number

Ass

igne

d RB

s





140 145 150 155 160 165 1700

5

10

15

20

25

TTI number

Ass

igne

d RB

s












12

5 10 15 20 25 306

8

10

14

16


Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629



5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()


X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119





5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2



Parameters Value






4 Conclusions





Acknowledgments


References

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










12

5 10 15 20 25 306

8

10

14

16


Y 1079

User

X 10Y 1187

X 15Y 125

X 20Y 1305

X 25Y 1449

Dat

a rat

e (M

bps)

X 30Y 1529

X 5Y 1102

X 10

X 5

Y 1307

X 15Y 1348

X 20Y 1428

X 25Y 1572

X 30Y 1629



5 10 15 20 25 301

2

3

4

5

6

7

8

9

10

X 5Y 2145

User

Dat

a rat

e atte

nuat

ion

ratio

()


X 10Y 9134

X 15Y 7213

X 20Y 8581

X 25Y 7793

X 30Y 6119





5 10 15 20 25 30

4

45

5

55

6

65

7 X 30Y 6566

User

X 25Y 6466

X 20Y 608X 15

Y 5817X 10Y 545

BLER comparison

X 5Y 482

X 30Y 6516

X 25Y 6366

X 20Y 597X 15

Y 575

X 10Y 5167

X 5Y 4667


BLER

lowasteminus2



Parameters Value






4 Conclusions





Acknowledgments


References

















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Acknowledgments


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









research article the communication solution for lte system

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