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674 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 20, NO. 2, APRIL 2005

Performance Analysis of OFDM Systems forBroadband Power Line Communications Under

Impulsive Noise and Multipath EffectsY. H. Ma, P. L. So, Senior Member, IEEE, and E. Gunawan, Member, IEEE

AbstractThe impulsive noise and multipath effects are themain reasons to cause bit errors in power line communications.In this paper, the bit error rate (BER) performance of the orthog-onal frequency division multiplexing (OFDM) system under theimpulsive noise and multipath effects are theoretically analyzed interms of closed form formulas. Through the analysis, it is shownthat OFDM can mitigate the adverse effect of the impulsive noiseand only the heavily disturbed impulsive noise will interfere theBER performance of the OFDM system. It is also shown that theadverse effect of multipath is more serious than that of impulsivenoise. In this paper, the guard interval is used to improve the BERperformance of the OFDM system. As the longer guard interval isinefficient in using the signal power, the optimum guard intervalthat can achieve the best BER performance is studied.

Index TermsBit error rate (BER), impulsive noise, multipatheffect, OFDM, power line communications.

I. INTRODUCTION

I N RECENT years, the use of existing power lines fortransmitting data and voice has been receiving interest.The advantages of power line communications (PLC) are veryobvious because of the ubiquity of power lines and poweroutlets. The potential of power lines to deliver the broadbandservices, such as fast Internet access, telephone and fax ser-vices, and home networking is an emerging new technologyin the telecommunications industry. However, there are somechallenges for communications over power lines such as noise,attenuation and multipath propagation.

Noise in a power line is not an additive white Gaussian noise(AWGN) [1][3]. The noise is categorized into four differenttypes of noise in [1] and extended into five types in [2]. Thefive types of noise are colored background noise, narrowbandnoise, periodic impulsive noise asynchronous to the mains fre-quency, periodic impulsive noise synchronous to the mains fre-quency and asynchronous impulsive noise. The first three typesof noise usually remain stationary and are summarized as back-ground noise. The last two noise types are time-variant and areclassified as impulsive noise. The impulsive noise has a shortduration with random occurrence and a high power spectral den-sity (PSD). It may cause bit or burst errors in data transmission.

Manuscript received July 2, 2004. This work was supported by the Schoolof Electrical and Electronic Engineering, Nanyang Technological University,Singapore. Paper no. TPWRD-00315-2004.

The authors are with Network Technology Research Center, School of Elec-trical and Electronic Engineering, Nanyang Technological University, Singa-pore.

Digital Object Identifier 10.1109/TPWRD.2005.844320

In [2], the arrival rate and power spectral density of impulsivenoise are measured and a model based on a partitioned Markovchain is developed to describe the impulsive noise. Results in[3] reveal that the arrival of impulsive noise follows the Poissondistribution. The noise scenarios in Singapore power lines aremeasured and studied in [4].

Multipath effect is another serious problem for PLC becausethe distribution of power lines is complicated. Signal propaga-tion usually travels along a shortest path between transmitter andreceiver, but additional paths (echoes) should also be consid-ered. This will result in a multipath scenario with frequency se-lective effect. The multipath of power line channel is researchedand the echo model is developed in [5], [6].

The impulsive noise and multipath effects encourage re-search on communication techniques that can effectively facesuch a hostile environment. Orthogonal frequency divisionmultiplexing (OFDM) is such a good candidate for broadbandPLC. OFDM can perform better than single carrier when thechannel is interfered by impulsive noise, because it spreadsthe effect of impulsive noise over multiple symbols due todiscrete Fourier transform (DFT) algorithm. It also permits toseparate overall transmitted data in many parallel independentsubcarriers. The long symbol duration time makes OFDM toperform better than single carrier under the multipath effect.

In the early studies of the effect of impulsive noise, someresearches were involved in narrowband PLC [7], [8]. Forbroadband PLC, the effect of impulsive noise on the performanceof PLC networks is analyzed by using simulations in [9], [10].In radio communications, some researches on the effect ofmultipath on OFDM systems are studied in [11], [12]. However,because the channel characteristics of radio communicationsare different from those of PLC, it is desirable to study themultipath effect on PLC. In [13], [14], there are some studieson the bit error rate (BER) performances of OFDM systemsunder the multipath effect on PLC. However, among thesestudies, only the simulation results are provided, closed formformulas are not available. In this paper, the impulsive noiseand multipath effects on PLC are theoretically analyzed. Closedform formulas for the BER performance of the OFDM systemunder the impulsive noise and multipath effects are derived. Theoptimum guard interval to achieve the best BER performanceis also studied.

The paper is organized as follows. In Section II, the model forimpulsive noise is presented and the closed form formulas an-alyzing its effect on the OFDM system are derived. Section IIIderives the closed form formulas for the BER performance of

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MA et al.: PERFORMANCE ANALYSIS OF OFDM SYSTEMS 675

the OFDM system under the multipath effect. In Section IV,numerical results of the BER performance of the OFDM systemare presented and the validity of the derived formulas is verifiedby comparing the analytical results with the simulation results.The optimum guard interval that can provide the best BER per-formance is discussed in this section. Section V gives a con-cluding discussion.

II. EFFECT OF IMPULSIVE NOISE

The effect of impulsive noise on the OFDM system in radiocommunications is studied in [15]. However, because the im-pulsive noise in radio communications is different from that inPLC, the studies in [15] are not applicable to analyze the effectof impulsive noise on PLC. Noise in the power line is dividedinto background noise and impulsive noise [2]. To analyze theireffects on PLC, we assume the background noise as additivewhite Gaussian noise (AWGN) with mean zero and variance

, and the impulsive noise is given by

(1)

where is the Poisson process which is the arrival of the im-pulsive noise and is the white Gaussian process with meanzero and variance . This model can be physically thought ofas each transmitted data symbol being hit independently by animpulsive noise with a probability distribution and with arandom amplitude [15].

Let be the transmitted signal, then the received signal canbe expressed as

(2)

where is the noise given by

(3)

The probability density function of the noise is

(4)

where and are the real and imaginary parts of re-spectively, is the probability of the occurrence of the impul-sive noise, and is the Gaussian density defined as follows:

(5)

The occurrence of the impulsive noise has approximately aPoisson distribution, which means the arrival of the impulsivenoise follows the Poisson process with a rate of units persecond, so that the event of arrivals in seconds has the prob-ability distribution [3]

(6)

Fig. 1. AWGN, impulsive noise and symbol time.

Let the average duration time of each impulsive noise beand the duration time of the symbol be as shown in

Fig. 1. In time there could be more than one occurrences ofimpulsive noise. We define as the total average occurrenceof the impulsive noise duration in time and as the averageduration without the impulsive noise in this time , in whichduration only AWGN is present. According to (6),

(7)

A. Performance of Single Carrier BPSK UnderImpulsive Noise Effect

The BER of a single carrier BPSK is the average result underthe impulsive noise and AWGN as follows:

(8)

where and are the BER under the impulsive noise andAWGN respectively. According to the BER formula of BPSK,we have

(9)

(10)

where is the signal energy per bit, and are the powerspectral density of the impulsive noise and AWGN respectively.Hence, the BER of single carrier BPSK under the impulsivenoise is

(11)


B. Performance of OFDM Under Impulsive Noise EffectWhen the transmitted signal is OFDM symbols, the received

symbols after front end filtering and sampling, assuming perfectsynchronization, timing and an ideal channel, is given by [15]

(12)where is the BPSK modulation symbol and is thenumber of carriers of OFDM, and are the AWGN andimpulsive noise respectively.

The transmitted symbols are recovered from thereceived sequence by performing the points DFT.

(13)where is once again AWGN after DFT. is given by theDFT of the impulsive noise as follows [15]:

(14)

The impulsive noise is spread over data symbols due to theDFT operation, which is different from single carrier system, inwhich the impulsive noise will affect only one symbol.

The total noise PSD is

(15)where is the PSD of the overall noise which includesAWGN and impulsive noise. Let be the ratio of impulsivenoise power to AWGN power,

(16)

The BER of OFDM system under the AWGN and impulsivenoise interference is

(17)

Hence, when considering the effect of impulsive noise on theBER performance of the OFDM system, the signal to noise ratio

should be replaced by .

III. EFFECT OF MULTIPATH ON OFDM SYSTEMIn [6], the echo model was developed to model the power line

channel. In time domain, the channel can be described as theimpulse response function as follows:

(18)

where and are the amplitude and arrival time of the mul-tipath components respectively, and is the number of path

components of the impulse response of the channel. For PLC,we assume the channel response remains constant throughoutthe transmission of data, i.e., it can be regarded as time-invariantsystem. Hence, and are kept constant in the analysis.

The multicarrier transmitted signal is

(19)

where is the symbol of the th sub-channel at time interval , and for BPSK andQPSK modulation it is and respectively. is theresponse of the transmitter filter which is a rectangular pulsewith duration and amplitude 1.

(20)

where is the guard interval of the OFDM signal. The timedifference between the symbol duration and the guard in-terval is the effective symbol duration time .The OFDM symbol with guard interval (GI) is shown in Fig. 2.

The frequency of th subcarrier should satisfy the orthog-onal condition

(21)

When the multicarrier signal is transmitted through thechannel with the impulse response of , the received signal

is

(22)

where

(23)

and is the noise received at the receiver side. To simplifythe analysis, we assume as AWGN.

At the receiver side, the guard interval will be removed. Inthe th signal interval , the recovery of the dataassociated with the subcarrier is performed by taking the de-cision variable as

(24)

A. BER Performance of OFDM Without Guard IntervalWe first analyze the BER performance of the OFDM system

without the guard interval. When the guard interval is not used,thus . In the th signal interval ,

the input signal of the th decision becomes


Fig. 2. OFDM symbol with guard interval.

Assume the first path of the multipath received signal ismatched to the receiver, i.e., . In [6], the maximum delaycompared with is usually not longer than 1 s, which is lessthan . Thus, only the symbol immediately before the currentsymbol will cause interference to the current symbol. If we useBPSK with , then

(25)

where . and denote the cur-rent and previous symbols transmitted with subcarrier respec-tively. is 1 when and 0 otherwise. Because BPSKis used, only the real parts of and are used, i.e.,

and , with each equal to .The demodulated signal is

(26)

where

(27)is the real part of AWGN demodulated by th subcarrier and

is expressed by

(28)

When the demodulated subcarrier equals to the modulatedsubcarrier, i.e., , we have

(29)

Finally, we have

(30)In this formula, the first term represents the desired signal

component, the second term represents the inter symbol inter-ference (ISI) caused by the multipath effect, and the third termrepresents the inter carrier interference (ICI) related to the lossof orthogonality between the subcarriers. From (27) and (30),we can derive ISI and ICI as follows:

(31)

(32)Error occurs when assumed current symbol has

been transmitted, but the sampled received signal is less than0. Hence, the error probability on the condition of th subcarrieris

(33)For the ISI in (31), the value of the previous symbol is 1or with equal probability of 0.5. Thus, the error probabilityof (33) includes two parts as

(34)Because the ICI is created by a large number of paths and sub-

carriers, its resulting interference can be assumed as Gaussiandistributed. The condition decision variable is then Gaussiandistribution. With this assumption the error probability iscalculated as

(35)

When and , the expectation of in(30) is

(36)

The variance of , which contains the variance of all interfer-ence terms, is

(37)


where is given by

(38)

and is given by

(39)

Let be the normalized delay. Summarizing(35)(39), we have

(40)

where is the signal to noise ratio.Similarly, when and , the error

probability is

(41)

Substituting (40) and (41) into (34), we can obtain the BERformula. The BER formula derived above is only for the thsubcarrier. It has to be averaged over all the subcarriers. From(34), (40) and (41), it can be seen that there will be an error floorfor the BER performance of the OFDM system. The value of thiserror floor depends on the parameters of the channel impulseresponse , the symbol duration time and the number ofsubcarriers .

When the received signal is only affected by AWGN, the PSDof the noise is . However, in the PLC channel, the impul-sive noise will also interfere the received signals. The impulsivenoise will be spread over data symbols due to the DFT oper-ation. According to (15), the signal to noise ratio now becomes

. When the BER of OFDM system under the impulsivenoise and multipath effects is calculated, in (40) and (41)should be replaced by .

B. BER Performance of OFDM With Guard IntervalThe adverse effect due to the delayed signals can be removed

or reduced by using the guard interval. The guard interval caneliminate the effect of ISI and ICI effectively. The extensionof the guard interval for wider delay spread may improve thetransmission performance.

When the guard interval is considered, the channel impulseresponse can be rewritten as follows:

(42)

where are classified by the following inequalities:

When is less than , that means the delayed time of pathis less than , the delayed signal will not cause ISI or ICI

interference. However, when is larger than , the delayedsignal will cause ISI or ICI interference.

In the th signal interval , the input signal ofthe th decision can be achieved by using (24). Using the similarderivations as in Section III.A, we have

(43)and

(44)

where

(45)and

(46)


where

(47)and

(48)

The error probability can be obtained as follows: [see (49) at thebottom of the page].

Summarizing (49), we can have the BER formula of OFDMsystem with the guard interval under the multipath effect. Also,the BER formula derived above is only for the th subcarrier. Ithas to be averaged over all the subcarriers.

IV. NUMERICAL RESULTS

In order to verify the accuracy of the analytical formulas de-rived in the previous sections, we compare the BER perfor-mances of the analytical formulas with the results of computersimulations.

A. Effect of Impulsive NoiseThe parameters of the impulsive noise are obtained from

[2]. The impulsive noise is measured and categorized intothree scenarios, namely heavily disturbed scenario, mediumdisturbed scenario and weakly disturbed scenario. For theheavily disturbed impulsive noise, it is captured during theevening hours in a transformer substation in an industrialarea. The medium disturbed impulsive noise is measured ina transformer substation in a residential area with detachedand terraced houses. The weakly disturbed impulsive noiseis measured during nighttime in an apartment located in alarge building. The three impulsive noise scenarios are listedin Table I. In the table, IAT is the inter-arrival time of theimpulsive noise, which is the reciprocal of the arrival rate .

is the average noise duration time.

TABLE IPARAMETERS OF THE IMPULSIVE NOISE SCENARIOS

Fig. 3. Analytical BER performances of OFDM and single carrier BPSKsystems under three impulsive noise scenarios.

Fig. 3 shows the BER performance comparison of OFDM andsingle carrier BPSK systems under the effects of three impulsivenoise scenarios. In the analysis, by fixing the impulsive noise toAWGN power ratio and changing , we can obtain theBER performance curves. In the figure, there is an error floorfor the BER performance of the single carrier BPSK system.Continuing to increase will not improve the performanceeffectively. The reason is that in single carrier BPSK system, theimpulsive noise will affect only one or several symbols.

However, in OFDM system, the effect of the impulsive noiseis spread over data symbols due to DFT operation as de-scribed in (14). The BER performance can be improved rapidlywith the increase of , which means for OFDM system,increasing signal power can improve the BER performanceeffectively. From this point of view, OFDM performs betterthan single carrier BPSK. It is also observed that for mediumdisturbed Scenario II and weakly disturbed Scenario III, OFDMalways performs better than single carrier BPSK. Only theheavily disturbed impulsive noise will obviously interfere the

(49)


Fig. 4. Comparison of analytical and simulation results for the BERperformances of OFDM and single carrier BPSK systems under the heavilydisturbed Scenario I environment.

BER performance of the OFDM system. For heavily disturbedScenario I, when is greater than 8 dB, OFDM performsbetter than single carrier BPSK. Hence, OFDM can achievegood performance under the impulsive noise effect.

Fig. 4 shows the comparison of analytical and simulationresults of the BER performances of single carrier BPSK andOFDM systems under the heavily disturbed Scenario I environ-ment. The impulsive noise to AWGN power ratio is set as 10.In Fig. 4, it can be seen that the analytical results correspondwell with the simulation results. The error floor of single carrierBPSK is also observed in the results. At lower , the per-formances of both OFDM and single carrier BPSK are similarbecause in this region the white Gaussian noise plays the mainrole to cause bit errors.

B. Effect of MultipathIn the analysis, the channel response amplitude , arrival

time of multipath components and the number of path com-ponents are given in Table II. In the table, the multipathnumber is selected as 4. When the delay of the first path is as-sumed 0, the delay of other paths compared with the first path islisted respectively in the table. The bit rate is set at 10 Mbps.The symbol duration time is the result of the carrier number

and the bit rate , i.e., .Fig. 5 shows the BER performance of the OFDM system

under the effect of the multipath channel as described in Table II.In Fig. 5, without considering the guard interval (GI), there arethree scenarios with different carrier number , namely 32,64 and 128 respectively. Through the comparison, it is shownthat there is an error floor for each curve without the guard in-terval. These error floors are caused by the multipath effect. TheBER performance cannot be improved by increasing the signalpower. The reason is that there are ISI and ICI interferences inthe system, and increasing the signal power will also increasethe power of ISI and ICI. In order to improve the BER perfor-mance, an applicable solution is to increase the carrier numberto expand the symbol duration time and therefore the effect ofISI can be reduced as shown in Fig. 5.

Another effective method to improve the BER performanceis to use the guard interval to eliminate the effect of multipath,

TABLE IIPARAMETERS OF THE IMPULSE RESPONSE OF PLC MULTIPATH CHANNEL

Fig. 5. Comparison of analytical and simulation results for the BERperformance of OFDM system under the multipath effect.

as shown in Fig. 5. In this analysis, the guard interval is selectedas of the symbol duration time and the carrier number

. It is shown that, with the same carrier number, theBER performance of the OFDM system with the guard intervalcan be greatly improved compared with that without the guardinterval.

C. Effects of Both Impulsive Noise and MultipathFig. 6 shows the BER performance of the OFDM system

under both impulsive noise and multipath effects. The param-eters of the multipath channel are the same as those given inTable II. Because the heavily disturbed impulsive noise will ad-versely interfere the OFDM system, only the heavily disturbedScenario I in Table I is used in this analysis. As can be seenin Fig. 6, the analytical results correlate well with the simula-tion results with 32 and 64 carrier numbers. Increasing the car-rier number can improve the BER performance of the OFDMsystem under the impulsive noise and multipath effects. How-ever, for each of these curves with 32 and 64 carrier numbers,there is an error floor from 40 dB onwards, which is caused bythe multipath effect.

Through the comparison of the BER performance of theOFDM system with 128 carrier number under different valuesof impulsive noise to AWGN power ratio , it is shown thatalthough the impulsive noise will deteriorate the BER perfor-mance, this adverse effect is only observed at below45 dB. The effect of impulsive noise will be taken over by theeffect of multipath when increases from 45 dB. Thevalue of the BER error floor caused by the multipath effect willnot change with the impulsive noise to AWGN power ratio.Thus, it can be concluded that the main obstacle to achieve thegood BER performance of the OFDM system is the multipatheffect.


Fig. 6. BER performance of OFDM system under the impulsive noise andmultipath effects.

Fig. 7. Optimum guard interval for OFDM system under the multipath effectwith OFDM carrier numberM = 64.

D. Optimum Guard IntervalAs has been verified in Fig. 5, the guard interval can ef-

fectively improve the BER performance of the OFDM system.However, with the increase of the guard interval, the BER per-formance will become worse because the longer guard intervalis inefficient in using the signal power. On the other hand, withthe decrease of the guard interval, the BER performance will be-come worse as the shorter guard interval is unable to eliminatethe multipath effect.

As shown in Fig. 7, there is an optimum guard interval thatcan minimize the BER from a trade-off between the BER perfor-mance and the guard interval. In this analysis, dB,30 dB, and 32 dB, and are used. The other conditionsare the same as those given in Table II. When is deter-mined, there is an optimum guard interval at which the BER canreach the minimum value. When the guard interval reaches theoptimum value, the BER performance can be improved rapidlybecause the guard interval can eliminate the multipath effect.The signal power spent in the guard interval is worthy of suchimprovement. However, after the optimum value, the BER per-formance will deteriorate with the increase of the guard interval,because the cost paid for the guard interval in terms of wastingsignal power is larger than its contribution in eliminating themultipath effect. Hence, in order to achieve the best BER per-formance, the optimum guard interval must be used.

V. CONCLUSION

In this paper, the BER performance of the OFDM systemfor broadband PLC under the impulsive noise and multipath ef-fects has been theoretically analyzed in terms of closed formformulas. The validity of the derived formulas is confirmed bycomparing the analytical results of the BER performance withthe simulation results. From the analysis, it is concluded thatthe BER performance of the OFDM system under the effect ofimpulsive noise depends on the inter-arrival time, the averageduration time and the power spectral density of the impulsivenoise. Only the heavily disturbed impulsive noise will interferethe OFDM system. The adverse effect of multipath is more se-rious than the effect of impulsive noise. There is an error floor ofthe BER performance caused by the multipath effect. The multi-path effect can be overcome by using larger carrier number andoptimum guard interval. The optimum guard interval that canminimize the BER from a trade-off between the BER perfor-mance and the guard interval has been demonstrated.

REFERENCES

[1] O. G. Hooijen, A channel model for the residential power circuit used asa digital communications medium, IEEE Trans. Electromagn. Compat.,vol. 40, no. 4, pp. 331336, Nov. 1998.

[2] M. Zimmermann and K. Dostert, Analysis and modeling of impulsivenoise in broad-band powerline communications, IEEE Trans. Electro-magn. Compat., vol. 44, no. 1, pp. 249258, Feb. 2002.

[3] O. G. Hooijen, On the channel capacity of the residential power circuitused as a digital communications medium, IEEE Commun. Lett., vol.2, no. 10, pp. 267268, Oct. 1998.

[4] L. T. Tang, P. L. So, E. Gunawan, Y. L. Guan, S. Chen, and T. T. Lie,Characterization and modeling of in-building power lines for high-speed data transmission, IEEE Trans. Power Delivery, vol. 18, no. 1,pp. 6977, 2003.

[5] M. Zimmermann and K. Dostert, A multi-path signal propagationmodel for the powerline channel in the high frequency range, in Proc.1999 ISPLC Conf, pp. 4551.

[6] , A multipath model for the powerline channel, IEEE Trans.Commun., vol. 50, no. 4, pp. 553559, Apr. 2002.

[7] M. H. L. Chan and R. W. Donaldson, Amplitude, width, and interarrivaldistribution for noise impulses on intrabuilding power line communica-tion networks, IEEE Trans. Electromagnetic Compatibility, vol. 31, no.3, pp. 320323, Aug. 1989.

[8] M. H. L. Chan, D. Friedman, and R. W. Donaldson, Performance en-hancement using forward error correction on power line communicationchannels, IEEE Trans. Power Delivery, vol. 9, no. 2, pp. 645653, Apr.1994.

[9] G. Bianchi and G. Conigliaro, An hybrid reservation-polling MAC pro-tocol for powerline communications, in Proc. 2002 ISPLC Conf.

[10] Y. H. Ma, P. L. So, E. Gunawan, and Y. L. Guan, Modeling and analysisof the effect of impulsive noise on broadband PLC networks, in Proc.2004 ISPLC Conf., pp. 4550.

[11] M. Okada, S. Hara, and N. Morinaga, Bit error rate performances of or-thogonal multicarrier modulation radio transmission systems, in IEICETrans. Communications, vol. E76-B, Feb. 1993, pp. 113119.

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Y. H. Ma received the B.Eng. and M.Eng. degrees in electrical engineering fromShanghai JiaoTong University, Shanghai, China, in 1999 and 2002, respectively.He is now pursuing the Ph.D. degree at Nanyang Technological University,Singapore.

His research interest is power line communications.

P. L. So (M98SM03) received the B.Eng. degree with first class honors inelectrical engineering from the University of Warwick in 1993, and the Ph.D.degree in electrical power systems from Imperial College, University of London,in 1997.

He joined China Light & Power Company Limited, Hong Kong, as GeneralAssistant Engineer in 1980 and later as Second Engineer working in the field ofpower system protection. He is currently an Assistant Professor in the School ofElectrical and Electronic Engineering, Nanyang Technological University, Sin-gapore. His research interests are power system dynamics, stability and control,FACTS, power quality and power line communications.

E. Gunawan (M90) received the B.Sc. degree in electrical and electronic en-gineering from the University of Leeds, U.K., in 1983 and the M.B.A. and thePh.D. degrees, both from Bradford University in 1984 and 1988, respectively.

From 1984 to 1988, he was a Satellite Communication System Engineer atCommunication Systems Research Ltd., Ilkley, U.K. In 1988, he moved to SpaceCommunication (SAT-TEL) Ltd., Northampton, U.K. He joined the School ofElectrical and Electronic Engineering, Nanyang Technological University, Sin-gapore, in 1989, where he is currently an Associate Professor. His research in-terests are in the fields of digital communications, mobile and satellite commu-nications, error coding, spread-spectrum and power line communications. Hehas published over 100 international research papers and has been a consultantto local companies on the study of Next Generation WLAN, DECT System, andBluetooth.

tocPerformance Analysis of OFDM Systems for Broadband Power Line CoY. H. Ma, P. L. So, Senior Member, IEEE, and E. Gunawan, Member,I. I NTRODUCTIONII. E FFECT OF I MPULSIVE N OISE

Fig.1. AWGN, impulsive noise and symbol time.A. Performance of Single Carrier BPSK Under Impulsive Noise EffeB. Performance of OFDM Under Impulsive Noise EffectIII. E FFECT OF M ULTIPATH ON OFDM S YSTEMA. BER Performance of OFDM Without Guard Interval

Fig.2. OFDM symbol with guard interval.B. BER Performance of OFDM With Guard IntervalIV. N UMERICAL R ESULTSA. Effect of Impulsive Noise

TABLE I P ARAMETERS OF THE I MPULSIVE N OISE S CENARIOSFig.3. Analytical BER performances of OFDM and single carrier BFig.4. Comparison of analytical and simulation results for the B. Effect of Multipath

TABLE II P ARAMETERS OF THE I MPULSE R ESPONSE OF PLC M ULTIPATHFig.5. Comparison of analytical and simulation results for the C. Effects of Both Impulsive Noise and Multipath

Fig.6. BER performance of OFDM system under the impulsive noiseFig.7. Optimum guard interval for OFDM system under the multipaD. Optimum Guard IntervalV. C ONCLUSIONO. G. Hooijen, A channel model for the residential power circuitM. Zimmermann and K. Dostert, Analysis and modeling of impulsiveO. G. Hooijen, On the channel capacity of the residential power L. T. Tang, P. L. So, E. Gunawan, Y. L. Guan, S. Chen, and T. T.M. Zimmermann and K. Dostert, A multi-path signal propagation moM. H. L. Chan and R. W. Donaldson, Amplitude, width, and interarM. H. L. Chan, D. Friedman, and R. W. Donaldson, Performance enhG. Bianchi and G. Conigliaro, An hybrid reservation-polling MAC Y. H. Ma, P. L. So, E. Gunawan, and Y. L. Guan, Modeling and anaM. Okada, S. Hara, and N. Morinaga, Bit error rate performances L. Vandendorpe, Multitone system in an unlimited bandwidth multiK. Kuri, Y. Hase, S. Ohmori, F. Takahashi, and R. Kohno, PowerliE. Del Re, R. Fantacci, S. Morosi, and R. Seravalle, Comparison M. Ghosh, Analysis of the effect of impulsive noise on multicarr

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