Filter Bank Based Notch Filter for Interference Cancellation in UWB Systems

Transcription

1 Internatonal Journal of Advane Researh and Innovaton Flter Bank Based Noth Flter for Interferene Canellaton n UWB Systems Saurabh Srvastava *, a, b, O.P. Sahu b a Department of Eletrons & Communaton Engneerng, Teerthanker Mahaveer Unversty, Moradabad, Inda b Department of Eletrons & Communaton Engneerng, NIT Kurukshetra, Kurukshetra, Inda Artle Info Artle hstory: Reeved 5 Marh 2014 Reeved n revsed form 20 Aprl 2014 Aepted 28 May 2014 Avalable onlne 15 June 2014 Keywords Multarrer, Flter Bank, Orthogonal Frequeny Dvson Multplexng (OFDM), Wreless-Loal Area Network (WLAN), Sub-Band Deomposton, Narrowband Interferene, Modelng, Canellaton, Adaptaton 1. Introduton The prmary onern of any ommunaton engneer s the bandwdth of the transmtted or reeved sgnal and the nose enountered n the hannel durng the transmsson reepton proess. The fous area of modern ommunaton systems s towards utlzng multarrer (MC) tehnques for transmsson and reepton, and towards mnmzng the nose and nterferene enountered durng the ommunaton proess. In wdeband mult arrer ommunatons, the hannel bandwdth s splt nto varous bns of smaller bandwdth referred to as sub-arrers or sub-hannels. The sgnal to be transmtted s then modulated wth the subarrer frequeny usng dgtal modulaton methods suh as Quadrature Phase Shft Keyng (QPSK), Quadrature Ampltude Modulaton (QAM) et. as n Orthogonal Frequeny Dvson Multplexng (OFDM). To avod nterferene between the neghborng subarrers, the subarrers are made orthogonal by ntrodung guard nterval [1]. The ultra-wdeband (UWB) s referred by the frequeny band of 3.1 Hz to 10.6 GHz by the Federal Communatons Commsson (FCC). It oexsts wth the other lensed and unlensed ommunaton systems operatng n the same spetrum but wth a very low power spetral densty (PSD)[2]. It s known that the proess of removal of narrowband nterferene (NBI) s qute omplex for wdeband and ultra-wdeband systems owng to ther low PSD. Also, the nterferene oupes a muh narrower frequeny band but has a hgherpower spetral densty than the large bandwdth nformaton. On the other hand, the UWB systems are arrer less systems. So, Gaussan pulses and ts dervatves are Correspondng Author, E-mal address: saurabh_ntk@yahoo.om All rghts reserved: Abstrat The prmary onern of any ommunaton engneer s the bandwdth of the transmtted or reeved sgnal and the nose enountered durng the transmsson reepton proess. We analyze the effets of narrowband nterferene n Multarrer UWB systems suh as short dstane IEEE a system. It s known that the proess of narrowband nterferene anellaton s qute omplex espeally for ultra-wdeband systems due to ther power spetral densty as low as -41dBm/MHz reommendatons by the FCC. We revew the model for narrow band nterferene and use the statstal property of orrelaton to determne the nterferene power spetral densty. We revew the sub band proessng of UWB sgnals and apply noth flterng after measurng the threshold to elmnate the nterferene. We propose a novel mehansm for generaton of the requred noth flter usng the sub band sgnals generated after the sub band deomposton of the UWB sgnal usng flter banks. The proposed mehansm may be appled n onjunton wth the other flter bank based multarrer systems that have the advantage of better sde-band attenuaton of sgnals than ommonly used OFDM system. employed to generate the baseband UWB sgnal [3]. Wdeband sgnal usually has autoorrelaton propertes qute smlar to those of AWGN (Adaptve Wde Gaussan Nose), so flterng n the frequeny doman s possble [4]. In ths paper, we show that orrelaton between the reeved samples n an UWB-OFDM based Wreless-Loal Area Network (WLAN) a or Hgh Performane Rado LAN (HperLAN) type 2 systems may be used for determnaton of NBI PSD. The HperLAN type 2 system also has smlar PHY layer parameters as a and the error performane of both the ultra-wdeband mehansms s the same [5]. Hene, n ths paper we would fous on IEEE a systems. We onsder the narrowband nterferene as ether a sngle tone nterferene sgnal or a narrow bandwdth nterferene sgnal. The ssue of NBI suppresson n multarrer wdeband systems s of prmary mportane n suh systems and has been studed extensvely n the last few years. Two man types of approah are generally adopted. The frst nvolves varous frequeny exson methods, where the orrupted frequeny bns of the multarrer symbols are exsed or ther usage avoded. The seond approah or the anellaton tehnques am at elmnatng or mtgatng the effet of the NBI on the reeved multarrer sgnal [6-10]. We hoose the method for deteton of the NBI usng the orrelaton of the reeved sgnals, and then apply flter banks to derve the noth flter that s further used for the mtgaton of the NBI. The paper s organzed as follows: frst we revew the multarrer ommunaton, Flter Bank sub band deomposton, OFDM and the UWB IEEE a standard. Next we desrbe the NBI deteton and mtgaton tehnques. We also use the sngle tone and 495

2 Internatonal Journal of Advane Researh and Innovaton narrowband nose models n dervng at the orrelaton propertes of the reeved ultra-wdeband OFDM sgnal. The smulaton model for NBI suppresson n UWB systems s desrbed n next seton. In next seton we present the smulaton results for NBI suppresson n UWB hannels and multarrer systems. Fnally, Seton onludes the paper gvng future dreton and suggestng possble applaton senaros of the researh work. 2. Revew of Multarrer Systems In multarrer (MC) ommunaton systems, the data s transmtted over many frequenes nstead of a sngle arrer frequeny. Ths s done by dvdng the wdeband hannel nto several sub-bands wth mld fadng. Ths has the advantage of better hannel estmaton and equalzaton. Also, MC symbol s longer n duraton than sngle arrer (SC) symbol whh helps redue synhronzaton omplexty of MC system. A general representaton of MC modulaton sheme s shown n fg 1. 0 Seral to Parallel 1 M 1 Modulator vt () Here, the seral nput s splt nto M parallel streams n the Seral to Parallel Convertor. 0, 1, 2,..., N 1 Then, the nput btrate R s redued to R/ M n eah of the M parallel sequenes. The dsrete symbols are modulated by shftng to desred frequeny. The enter th frequeny of the n sub-hannel s gven by 2 n 0 n, n 0,1,2,..., M 1, (1) T Where 0 the enter frequeny of s the lowest subhannel and M s the total number of sub-hannels. The transmtted sgnal s gven by M 1 (2) v( t) ( l) g ( t lt)exp( j t), n 0,1,2,..., M 1 n n n n0 l In OFDM, the bandwdth s splt nto M sub-bands. Eah sub-band s used by one snusodal sub-arrer. The baseband sgnal n OFDM s represented as x( t) A ( k) h( t kt )exp( j t) T k M1 1 2 M k 0, (3) Where ht () s a retangular pulse of duratont, and A ( k ) are QAM or QPSK symbols. The OFDM symbol duraton s T. Eah of the M sub-arrers s entered at frequeny f, 0,1,2,..., M 1. T Fg: 1. Multarrer Modulaton Sheme The spetrum of the sub-arrers s obtaned by the onvoluton of the Fourer transform of exponental sgnal wth the Fourer transform of the retangular pulse. Hene the spetrum of eah sub-arrer s a sn funton entered at f, 0,1,2,..., M 1. T OFDM based a system has a hannel spang of 20 MHz, FFT sze of 64, wth subarrer modulaton sheme of Bnary Phase Shft Keyng (BPSK), QPSK, 16-QAM or 64-QAM, the useful symbol length of 3.2 µs, and subarrer spang of KHz. Usng the 5 GHz band gves a a sgnfant advantage, sne the 2.4 GHz band s heavly used to the pont of beng rowded. Degradaton aused by suh onflts an ause frequent dropped onnetons and degradaton of serve. OFDM has fundamental propagaton advantages when n a hgh multpath envronment, suh as an ndoor offe, and the hgher frequenes enable the buldng of smaller antennas wth hgher RF system gan whh ounterat the dsadvantage of a hgher band of operaton. OFDM s the regarded as natural hoe for hgh speed relable Multarrer ommunatons for short range systems. The dvson of hannel nto sub-bands s as shown n the fgure 2. As shown n fg.2, the entre hannel bandwdth s dvded nto M unform sub-bands (sub-hannels n OFDM). Ths may be done by usng a smple lowpass flterng of the hannel wth a prototype flter (as shown for sub-hannel 0), and repeatng tll sub-hannel M 1. Clearly, all sub-hannels exept sub-hannel 0 are the modulated (shfted) opes obtaned wth the bandpass versons of the prototype flter. 496

3 Internatonal Journal of Advane Researh and Innovaton H( ) M 1 f Fg: 2. Sub-Band Splttng of Channel 2.1 Sub Band Splttng Usng Flter Banks A flter bank s basally a group of flters performng a spealzed task. In many ommunaton applatons, t s often requred to splt a wdeband sgnal nto smaller bandwdth omponents or sub-bands for effetve transmsson of data. The natural way to perform ths s usng flters. For multarrer ommunaton systems, ths s performed easly usng analyss- synthess flter bank strutures that dvde the reeved sgnal nto several sub hannels (analyss part), and reonstrut the orgnal sgnal xn ( ) Fg: 3. Unform Dematng M-Channel (Analyss) Flter Bank yˆ 0( m) yˆ 1( m) yˆ 2( m) yˆ ( m) M 1 H () z 0 H () z 1 H () z 2 HM () 1 z M M M M M M M M G () z 0 G () z 1 G () z 2 GM () 1 z xn ˆ( ) Fg: 4. Interpolatng M-hannel (Synthess) Flter Bank y ( m) 0 y ( m) 1 y ( m) 2 ym ( ) 1 m from the sub hannels (synthess part), after some optonal proessng. In sgnal proessng, unform dematon Flter Bank has the above property of sub-arrer dvson and s shown n fgure 3. Suh a flter bank makes the system effent by lowerng the nput samplng frequeny by M. Ths s followed by the optonal sub-band proessng of the output sgnals. The reverse operaton,.e. sub-band sgnal ombnng s arrer out usng nterpolaton flter bank or synthess bank, as shown n fgure 4. Here, yˆ ( m), 0,1,2,.. M 1 are the estmated values of sub-band that are passed to a bank of upsamplers. The upsamplers nrease the samplng frequeny exatly n the nverse rato of dematon. The upsampled sgnals are then gven to a set of flters that synthesze the ntal wdeband sgnal from ts sub-bands, and provde an estmated value of t, represented by xn ˆ( ). 2.2 WLAN a The IEEE group of standards popularly alled as W-F, has ts subset as the a standard. Ths standard works n the 5 GHz unlensed ISM band, that les wthn the UWB spetrum. The a has 12 overlappng hannels, 8 dedated to ndoor and 4 for pont to pont ommunaton. It fnds applaton n short dstane wreless ommunaton wthn a range of about 30m. It uses OFDM and has a hannel wdth of 20MHz. The a RF sgnal onssts of 52 OFDM subarrers. Of these 48 are used for the data transmsson and four are used as plot subarrers. The separaton between the ndvdual subarrers s MHz. Ths results from the fat that the 20 MHz bandwdth s dvded by 64. Although only 52 subarrers are used, oupyng a total of 16.6 MHz, the remanng spae s used as a guard band between the dfferent hannels. As wth many data transmsson systems, the generaton of the sgnal s performed usng dgtal sgnal proessng tehnques and a baseband sgnal s generated. Ths s then uponverted to the fnal frequeny. Smlarly for sgnal reepton, the nomng a sgnal s onverted down to baseband and onverted to ts dgtal format after whh t s proessed dgtally. 497

4 Internatonal Journal of Advane Researh and Innovaton PSD GPS PCS Bluetooth, WLAN IEEE b, Cordless Phone, Mrowave ovens WLAN IEEE a -41dBm/MHz Nose Floor UWB spetrum FCC part 15 lmt Frequeny (n GHz) Fg: 5. Spetrum rossover of narrowband nterferes n UWB systems [15] 2.3 OFDM System OFDM s the most wdely used MC modulaton tehnque presently. The bas OFDM transmtter system based upon fg.1, s shown as n fg. 6 sgnal. Fnally, The P/S onvertor ats as a frequeny/tme mapper. To ensure orthogonalty between the sub-arrers, the sub-arrer spang s made the nverse of OFDM symbol duraton. For N pont IFFT (or FFT), the total bandwdth beomes N tmes of subarrer- spang. Also after the CP nserton, the symbol duraton nreases. Fg: 6. OFDM Transmtter [12] As shown n fg. 6, the S/P onvertor ats as a Tme/Frequeny mapper. The nput data s[ n, k] s fed nto the IFFT blok that generates the requred tme doman waveform N k 1 j2 d[ n, ] s[ n, k] e N, 0,1,..., N N k0 To the output from IFFT blok, Cyl Prefx (CP) s added. The Cyl Prefx ats lke guard nterval and makes equalzaton easy. The data s agan onverted nto seral form and transmtted. The reverse operatons our n OFDM reever seton as shown n fg. 7. In the reever seton, CP s dsarded after the onverson from seral data to parallel data. Ths s followed by FFT blok that generates the requred frequeny doman Fg: 7. OFDM Reever [12] The usage of large CP ensures no delay spread n reeved OFDM waveform. In OFDM the equalzaton employed at the reever sde, and s Tme Doman Equalzaton (TDE) before removal of CP and Frequeny Doman Equalzaton (FDE) after the FFT operaton. The applaton of FDE provdes almost flat fadng at the subarrer level, whh reeps n as ICI terms n frequeny doman. The ICI s redued pratally by redung OFDM symbol duraton (.e. nreasng sub-arrer wdth) or by transmt pulse shapng. For a, the OFDM transmtted waveform s shown n fg

5 Internatonal Journal of Advane Researh and Innovaton Fg: 8. The Transmtted OFDM Waveform 2.4 FBMC Systems A flter bank multarrer system an be mplemented usng the analyss and synthess flter bank s as shown n fg. 9. The transmtted sgnal xn [ ] s found to be M 1 k, l k s (4) l k0 x[ n] s g [ n ll ] Where M s the no. of subarrers, s kl, s the l th symbol n k th subarrer, L s s the no. of symbols per transmt symbol spang, and g k[ n ] s the synthess flter for the k th subarrer. At the reever part, the estmated l th symbol n k th subarrer, ˆk, l s 0,l s s gven as g [ n ] 0 sˆ k, l ( y[ n] hk [ n]) n lls (5) Where yn [ ] s the reeved sgnal and h [ n ] s the mpulse response of the analyss flters for the k th subarrer. Defnng L, where L M, as no. of samples per symbol duraton. For OFDM, s kl, are QAM symbols and L s L. The synthess and analyss flters are defned as kn g [ n] h [ n] p[ n] W (6) k k L Where the prototype flter and 0 elsewhere s of length WL pn [ ] L p, and 1 L k for n=0, 1,..,L-1 j2 / L e (7) We have hosen FBMC aganst OFDM system, as FBMC system provdes more out of band power rejeton than OFDM. Moreover, FBMC s more bandwdth effent than OFDM. The nreased omplexty by usng FBMC aganst OFDM an be justfed by the spetral haratersts of the FBMC sub-arrers n provdng sgnfantly hgh suppresson to out of band radaton and to exellently partton the wdeband spetrum. Moreover, as the adaptve systems need tme to adapt to the nput data, so t s benefal to splt the nput sgnal and apply the adaptve nterferene anellaton log n parallel over eah sub-arrer. It s expeted that a far mprovement n the system performane shall be observed wth parallel operaton of adaptve seton on the sub-arrers. h [ n ] 0 s ˆ0, l s kl, g [ ] k n xn [ ] Channel yn [ ] h [ ] k n s ˆk, l sm 1, l gm [ ] 1 n hm [ ] 1 n sˆm 1, l Fg: 9. General FBMC System [13] 3. NBI Deteton and Mtgaton Tehnques The ssue of NBI suppresson n wdeband OFDM systems s of prmary mportane n suh systems and has been studed extensvely n the last few years. Two man types of approah are generally adopted. The frst nvolves varous frequeny exson methods, whereby the affeted frequeny bns of the OFDM symbol are exsed or ther usage avoded. The seond approah s related to anellaton tehnques whh are amed at elmnatng or mtgatng the effet of the NBI on the reeved sgnal. In ths paper, a method for NBI anellaton based on adaptve 499

6 Internatonal Journal of Advane Researh and Innovaton omplex dgtal flterng, usng the Least Mean Squares (LMS) algorthm to adapt to the entral frequeny of the NBI s presented and the method s ompared to other mtgaton tehnques. The proposed method offers onsderable benefts, nludng low omputatonal omplexty. The NBI arses due to narrowband systems operatng n the UWB frequeny band tself, and have predetermned enter frequenes and bandwdths. The most probable nterferes nlude Fxed satellte systems and WLAN a. The effet of NBI s shown n fg. 10. Fg: 10. Narrowband Interferene Corruptng OFDM Sgnal of WLAN a [16] The most promnent soure of NBI s the IEEE A WLAN system wth frequeny alloatons as shown n fg. 5, and table I. Band (GHz) UNII lower band ( ) UNII mddle band ( ) UNII upper band ( ) Table: 1. Frequeny alloatons for WLAN a [14] Channel No Centre Frequeny (MHz) Max. power output (wth upto 6dB antenna gan) 40 mw (2.5 mw/mhz) 200 mw (12.5 mw/mhz) 800 mw (50 mw/mhz) The man fators haraterzng the nterferene are ts model, the enter frequeny and ts bandwdth. There may be varous senaros dependng upon values of these fators. Nevertheless, the man objetve here s to mtgate the nterferene from the nterferer. We assume that the NBI s a sngle tone sgnal gven by ( t) A 2P os(2 f t ) (8) Where A s the hannel gan, P s the average power, f s the frequeny and s the phase of the nterferng snusod. For the ase where the nterferene has a narrow bandwdth, we assume t as a zero mean Gaussan random proess and ts PSD an then by defned as P, / 2 / 2 nt f B f f B S ( f) (9) 0, otherwse Here B s the bandwdth of the nterferer, frequeny of the nterferer and spetral densty nluded n bandwdth B. f s the enter P nt s the nterferene power The reeved sgnal an be shown as r( t) w( t) ( t) n( t) (10) Where wt () s the transmtted ultra-wdeband sgnal, t () s the NBI and nt () s the AWGN wth PSD of N 0. The orrelaton haratersts of transmtted ultra-wdeband sgnal are very muh smlar to that of AWGN. Hene, wt () an be assumed to be a part of nt (). Also, assumng that the nterferene s not orrelated to the AWGN and AWGN has mpulsve autoorrelaton. Ths gves the orrelaton between the reeved samples for sngle tone NBI as 2 R ( ) P A os(2 f ) N ( ) (11) Where s the duraton between reeved samples. For the band lmted nterferer ase, the autoorrelaton between reeved sgnal samples s gven as R ( ) 2P Bos(2 f )sn( B ) N ( ) (12) nt

7 Internatonal Journal of Advane Researh and Innovaton Frst we onsder the senaro where the nterferene s a sngle tone sgnal wth known frequeny f, n order to determne the average power of the nterferer, the orrelaton between the reeved sgnals s omputed. Choosng a value of approxmately but not equal to zero serves our purpose. For ths we take mnute nrements n between 0+ and 500ns. Usng (4) and from the obtaned orrelaton values, a deson an be made about NBI and nt P an be determned. Another senaro onssts of nterferene beng band lmted sgnal and f s known. Consderng the fat that the bandwdth of WLAN a system s 20 MHz and has a maxmum value of 500 ns, B 1. Hene, sn( B ) 1, Now, usng the orrelaton values of reeved sgnals the exstene of NBI an be verfed and P determned. nt Another senaro s when the enter frequeny s not known but the spetral nature of nterferene s known. The orrelaton values ndate the presene of NBI, but t would be dffult to determne nterferene PSD. In ths ase, f the enter frequeny of band lmted nterferer s onfned to a ertan regon (wthn 20 MHz), and s made very small, then R () an be omputed agan, and P nt an be determned. If unertanty of f nreases,.e. f f les nbetween UNII lower band and mddle band ( MHz), then f has unertanty of 140 MHz. In ths ase, has to be smaller than 1 ns. Ths hgh samplng rate of reeved sgnal s mpratal due to urrent hardware lmtatons. Observng that the reeved sgnal autoorrelaton has a snusodal nature, hene ths suggests repeatng values of to exst for same orrelaton value. Consderng the two sded maxmum shft n enter frequeny as f, and the perodty of the osne term n equaton (12), we an wrte f f k os(2 ( f ) ) os(2 ( f )( )) 2 2 f f 2 (13) Where k s any nteger. Hene, by nreasng a pratal value an be determned for samplng of orrelaton 1 values, provded s an nteger. In our WLAN f f 2 f a ase, as f s always less than 625 MHz, and takes spef nteger values n between 5180 and 5805 MHz, f f 2 s always an nteger, thereby justfyng (12). For the OFDM based a system, the NBI nterferene anellaton an be done by desgnng sutable noth flter at the loaton of the nterferene. Fg: 11. A Bas Gaussan Pulse Fgure 11 shows the bas Gaussan mono pulse used n the smulaton for generaton of UWB pulse wth a pulse wdth of 0.5 ns. The seond dervatve of the monopulse was used to generate the UWB pulse for smulaton purpose as shown n fgure 12. Fg: 12. Seond Dervatve of Gaussan Pulse Used for UWB Sgnal Generaton Next, the PSD of the transmtted UWB sgnal, the nose sgnal and the omposte sgnal s shown n fg

8 Internatonal Journal of Advane Researh and Innovaton 4. Noth Flterng Sheme Usng Sub Band Deomposton Knowng the expeted f of the sngle tone nterferene, the dea s to desgn a noth flter entered at f. The steps for suh a desgn may be gven as : Step 1: Identfy the nterferene frequeny f. Step 2: Partton the UWB nterferene band nto two bands lower band and upper band. Step 3: In eah band generate two sub-pulses s () t 1 and s () 2 t, by adjustng the ut-off frequenes of the two bands, and the pulse ampltudes and keepng n mnd the haratersts of omplyng wth the FCC mask, and S 1 ( f) S 2 ( f), (13) Step 4: Superpose the two sub-pulses to generate the desred UWB pulse, whh learly has a noth at f. Step 5: Transform the generated UWB pulse nto frequeny doman. Ths gves the requred noth flter. The smulaton model for the proposed nose anellaton system an be desrbed usng followng fg. 14 Ultra Wdeband Sgnal Generator Narrow band Interferene Sub band sgna l Sepa rator Interfere ne deteton log Interfere ne deteton log Interfer ene Canell aton and sub band sgnal ombn er Interferene anelled UWB sgnal Fg: 14. The Proposed System for Narrowband Interferene Deteton and Canellaton Log As shown n the above fgure, the transmtter onssts of an ultra-wdeband sgnal generator, whh passes the generated UWB sgnal to flter bank based sub-band sgnal separator that splts the wdeband sgnal nto two sub-bands. At the nput of the sub-band sgnal separator stage, onssts of a orrelaton reever that reeves the nput samples and determnes the orrelaton between reeved samples. Based upon these orrelaton values, the nterferer frequeny and power an be determned (approxmately n ase of the band lmted nterferene. For the reonstruton of the ultrawdeband data, two sub-pulses are generated for both the sub-bands, by adjustng ut-off frequeny of the bands under the FCC onstrants as gven n equaton (13). As the generated sub-pulses have transforms S ( f ) S ( f ), learly at the nterferene as 1 2 frequeny f, S( f ) S1( f) S2( f) 0. Hene a perfet noth would be obtaned at f, wth the frequeny response of the desgned noth flter as S( f ). The above algorthm was smulated wth MATLAB and the results verfed a very low absolute error of the order of 0.1%, n the nterferene anelled UWB sgnal as observed from fgure

9 Internatonal Journal of Advane Researh and Innovaton Fg: 15. Absolute Error n the Reonstruton of UWB Sgnal Fnally, the reonstruted UWB sgnal s shown n fg. 16 wth orrespondng perodogram. It an be verfed that ths mathes wth the perodogram of the UWB transmtted sgnal. The parameters used n the smulaton are as follows: UWB pulse wdth = 0.5 ns, a seond dervatve of Gaussan pulse was used as an UWB sgnal. To ensure that the spetrum oupany of the sgnal mathes wth the FCC reommendatons (-41dBm/MHz), a bandpass equrpple flter was desgned usng MATLAB, and the UWB pulse was shaped properly usng the flter. A omposte sgnal was formed by the addton of UWB pulse and Narrowband Interferene sgnal n aordane wth equaton (9). Usng the autoorrelaton values of the reeved sgnal samples, the nterferer frequeny was determned. The sub-band deomposton of the reeved sgnal was done wth flter banks generatng sub-pulses of desred haratersts for eah sub-band. Superposton of the sub-pulses was Fg: 16. Reovered UWB Sgnal and Its Perodogram performed resultng n the requred noth flter. One the requred noth flter s generated, the reeved UWB sgnal s noth fltered wth the generated flter to produe the nterferene anelled UWB sgnal. 5. Results Based on the smulaton setup and results obtaned we an say that the noth flterng proposed for narrowband nterferene anellaton n UWB systems usng the sub band deomposton of the sgnal has the defnte advantage of beng of an automat nature. Further, the noth s exatly at the nterferer frequeny whh s a lear advantage over adaptve flterng soluton of the same. Thrdly, the proposed method desrbes a deent applaton of sub-band flters n nterferene anellaton n UWB spetrum. 503

10 Internatonal Journal of Advane Researh and Innovaton Moreover, advantages of usng flter bank are numerous. Some of them nlude, more spetrally effent waveform generaton, sutablty for MC ommunatons. 6. Future Dreton Referenes [1] Jng Da and Yanme Wang, Study on OFDM Symbol Tmng Synhronzaton Algorthm, Internatonal Journal of Future Generaton Communaton and Networkng, 7(1), 2014, [2] S. Majh, P. Rhardson, Power Spetral Analyss of Orthogonal Pulse-Based TH-UWB Sgnals, Int'l J. of Communatons, Network and System Senes, 3(11), 2010, [3] I. Dotl, R. Kohno, Desgn of the Famly of Orthogonal and Spetrally Effent Uwb Waveforms, IEEE Journal of Seleted Top n Sgnal Proessng, 1(1), 2007, [4] Georg Ilev, Zlatka Nkolova, Vladmr Poulkov, Mglen Ovtharov, Narrowband Interferene Suppresson for MIMO MB-OFDM UWB Communaton Systems, Internatonal Journal on Advanes n Teleommunatons, 3(1 & 2), 2010, 1-8. [5] Deva K. Borah, Rttwk Jana and Anastasos Stamouls, Performane Evaluaton of IEEE a Wreless LANs n the Presene of Ultra-Wdeband Interferene, WCNC 2003, 1, 2003, [6] A. Batra, J. Balakrshnan, G. Aello, J. Foerster, A. Dabak, Desgn of a multband OFDM system for realst UWB hannel envronments, IEEE Transatons on mrowave theory and tehnques, 52(9), 2004, [7] R. Fsher, R. Kohno, H. Ogawa, H. Zhang, K. Takzawa, IEEE P workng group for wreless personal area networks (WPANs), DS-UWB proposal update, [8] H. Sheng, A. Hamovh, A. Molsh,, J. Zhang, Optmum ombnng for tme hoppng mpulse rado Further researh nludes the applaton of the proposed struture n onjunton wth other flter bank based strutures and probable modfatons at the physal layer of suh a system. A typal example ould nlude FBMC-SMT systems to norporate the proposed noth flter seton and analyze the performane of the system. UWB Rake reevers, Pro. IEEE Ultrawdeband Syst. Tehnol. (UWBST), Reston, VA, [9] A. Taha, K. Chugg, A theoretal study on the effets of nterferene on UWB multple aess mpulse rado, n Pro. IEEE Aslomar Conf. on Sgnals, Syst., Computers, 1, Paf Grove, CA, 2002, [10] I. Bergel, E. Fshler, H. Messer, Narrowband nterferene suppresson n mpulse rado systems, IEEE Conf. on UWBSyst. Tehnol., Baltmore, MD, 2002, [11] N. Boubaker, K. Letaef, A low omplexty MMSE-RAKE reever n a realst UWB hannel and n the presene of NBI, Pro. IEEE Wreless Commun. Networkng Conf, 2003,1, [12] Haleh Hossen, Roheza bt. A. Rashd, Sharfah Kamlah Syed Yusof and Norshela bt. Fasal, Study on UWB Systems n the presene of Narrowband Interferene, SCOReD proeedngs, 2008, Malaysa, 87-1,87-4. [13] Juan Fang, Zhao You, I-Tau Lu, Jalng L, Ru Yang, Comparsons of Flter Bank Multarrer Systems, LIAST 2013, IEEE long sland, 2013, 1-6 [14] 5 GHz Unlensed Spetrum (UNII), FCC ommsson doument, 2013, avalable onlne at [15] Followng the IDF: Ultra Wde Band Wreless Data Transfer Tehnology, avalable onlne at [16] Onur Ozemr, Zafer Sahnoglu, Jn Zhang, Narrowband Interferene Reslent Reever Desgn for Unknown UWB Sgnal Deteton, IEEE Internatonal Conferene on Communatons, 2008,