ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 TIME-FREQUENCY TRAINING OFDM WITH HIGH SPECTRAL EFFICIENCY AND RELIABLE PERFORMANCE IN LONG DELAY CHANNELS 1 R.Ranjitha, 2R.Thirunavukarasu 1 PG Scholar, 2Assist.prof Department of ECE, Oxford Engineering College, Trichy,tamilnadu, India Abstract---Orthogonal Frequency Division Multiplexing (OFDM) has recently been applied widely in wireless communication systems due to its high data rate transmission capability with high bandwidth efficiency and its robustness to multipath delay. TDS-OFDM performance suffer from fading channels with long delays andhas difficulty supporting high-order modulations like 256 QAM. Time-Frequency Training (TFT) OFDM compressive sensing and auxiliary information based subspace pursuit (A-SP) algorithms proposed to estimate the channel.Theobtainedchannelinformations are reduce the complexity of classical SPalgorithm.DPN OFDM and TDS OFDM schemes in both static and mobile environment Especially when the channel length is close or even larger than the guard interval length, the two schemes are can’t work. Keywords---Channel estimation (CE), compressive sensing(CS), long delays, orthogonal frequency division multiplexing(OFDM), ultrahigh definition television (UHDTV). 1. Introduction OFDM is considered an effective technique for broadband wireless communications because of its great immunity to fast fading channels and inter-symbol interference (ISI). It has been adopted in several wireless standards such as digital audio broadcasting (DAB), digital video broadcasting (DVB-T), the wireless local area network (WLAN) standard; IEEE 802.11a, and the metropolitan area network (W-MAN) standard; IEEE 802.16a OFDM partitions the entire bandwidth into parallel subchannels by dividing the transmit data bitstreaminto parallel, low bit rate data streams to modulate thesubcarriers of those subchannels. As such OFDM hasa symbol duration longer than single carriersystems(due to the lower bit rate of subchannels) which makes it very immune to fast channel fading and impulse noise.The frequency-selective multipath channel and the low complexity of the frequency domain equalizer, and the orthogonal frequency division multiplexing (OFDM) has been widely recognized as one of the key techniques for the next generation broadband wireless communication systems . The fundamental issue of OFDM is the block transmission scheme. Basically, three types of OFDM-based block transmission schemes: cyclic prefix OFDM (CP-OFDM) , zero padding OFDM (ZP-OFDM), and time domain synchronousOFDM(TDS-OFDM). The broadly used CPOFDM scheme utilizes the CP to eliminate the inter-block interference (IBI) as well as the inter-carrier-interference (ICI) . For both the CPOFDM and ZP-OFDM schemes, some allocated frequency-domainpilots are required for the both synchronization and channel estimation. The spectral efficiency is reduced and to solve the problem, instead of the Cyclic Prefix, the known training sequence (TS) such as the pseudorandom noise (PN) sequence, is used in the TDS-OFDM scheme instead of guard interval. Since the Training Sequence is known to the receiver, it can be used for both synchronization as well as channel estimation . The main drawback of TDS-OFDM is that theTS and the OFDM block will cause mutual inter-blockinterferences (IBI) to each other. Thus, iterative interference cancellation algorithm with high complexity has to beadopted for CE and channel equalization in TDS-OFDM systems. Under the severely fading channels, it isdifficult for 69 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 the iterative algorithm to perfectly remove theIBI when the maximum channel delay spread is large, whichis common in the single frequency network (SFN) environment . This will cause the degradation of the whole systemperformance and the difficulty to support the high-order modulations like 256 QAM to accommodate the emergingultrahigh definition television (UHDTV) service requirement(DVB-T2 has claimed to support the 256QAM for UHDTVservices. Some alternative solutions have been proposed to solve thisproblem .One exciting solution is the dual-PN addedOFDM (DPN-OFDM) scheme, whereby the PN sequence isduplicated twice to make the second PN sequence immunefrom the IBI caused by the preceding performance, it is not necessary to remove such interferencein the proposed scheme since the received PN sequence isonly used for the coarse channel path delay estimation. Themain CE task is transferred to the pilots in the OFDM block,which could combat the maximum channel delay spread closeto or even larger than the GI length. With the use of CSand sparse channel nature, the number of pilots embedded inthe OFDM block could be ignificantly reduced (about 1%of the total subcarrier number), and hence high spectral efficiency can still be maintained. Moreover, the coarse channelpath delay estimation is used as the auxiliary information toreduce the complexity of the classical CS algorithm, makingit applicable for practical systems. 2.Basic Concept of the TDS and DPN OFDM System In time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) distinguishes the standard cyclic prefix OFDM (CP-OFDM) by replacing CP with the prior known pseudo noise (PN) sequence as the guard interval (GI). The PN sequence can also work as the training sequence (TS) for both synchronization and channel estimation (CE) at the receiver side, which saves a large amount of frequency-domain pilots commonly used in CP OFDM.TDS-OFDM usually has higher spectral efficiency under the same condition. Additionally, faster and reliable synchronization could be also achieved by TDS OFDM .However, the main drawback of TDSOFDM is that the TS and the OFDM block will cause mutual inter-block interferences (IBI) to each OFDM block . Thus,the second received PN sequence can be directly used for CE,which avoids the iterative interference cancellation algorithmwith high complexity, and improves the performance overseverely fading channels. In this paper, consider time-frequency training OFDM (TFT-OFDM) scheme Which is modified from TDS-OFDM.The proposed CE method uses the PN sequence to acquire the coarse channel path delay estimation, while the exact channel impulseresponse (CIR) estimation. he conventional scheme of TDS-OFDMwhere the IBI caused by the preceding OFDM block tothecurrent TS has to be cancelled completely to achieve good other. Thus, iterative interference cancellation algorithm with high complexity has to be adopted for CE and channel equalization in TDS-OFDM systems. This result is an open problem of TDSOFDM: Under the severely fading channels, it is difficult for the iterative algorithm to perfectly remove the IBI when the maximum channel delay spread is large, which is common in the single frequency network (SFN) environment. It will cause the degradation of the whole system performance and the difficulty to support the high order modulations like 256 QAM to accommodate the emerging ultra-high definition television (UHDTV) service requirement(DVB T2 has claimed to support the 256QAM for UHDTV services).Some alternative solutions have been proposed to solve this problem . Fig.1: Distinct features of the IBIs in TDS OFDM As shown in Figure. 1, the IBI from the TS to the OFDM data block and the IBI caused by the OFDM block to the TS have distinct features in TDS-OFDM. 70 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 Fig.4:Proposed signal structure and the corresponding joint time-frequency channel estimation of the OFDM scheme. Fig.2:System models for CS-based TDS-OFDM. In Fig.2: The Compressive Sensing based TDSOFDM scheme utilizes the IBI-free region of size G within the received PN sequence for CE, but the maximum estimated channel length is limited to L = M − G + 1, where M is the length of the PN sequence .When the channel length L becomes larger, the size of the required IBI-free region becomes smaller, which leads to severe performance deterioration due to the reduced number of observations in CS.Unlike the conventional TDS- OFDM or CP-OFDM where the training information only exists in either the time or frequency domain. Fig.3: System model for DPN-OFDM. Fig.2: The DPN-OFDM scheme uses the second received PN sequence immune from IBI for CE.Thus, the iterative IBI removal can be avoided, but significant loss in spectral efficiency will be introduced. 3.PROPOSSED TFT- OFDM SYSTEM MODEL Unlike TDS-OFDM or CP-OFDM where the training information only exists in the time or frequency domain, Fig. 4 shows that TFT-OFDM has training information in both time and frequency domains for every TFT-OFDM symbol, i.e., the time-domain TS and the frequency-domains are grouped pilots scattered over the signal bandwidth are used in TFT-OFDM. The signal structure of the TFT-OFDM scheme in both the time and frequency domain. In the time domain, the ith TFT-OFDM symbol si =[si,−M··· si,−1 si,0si,1 ··· si,N−1] T is composed of the known time-domain TS ci=[ci,0 ci,1 ··· ci,M−1]T and the OFDM data block xi=[xi,0 xi,1 ··· xi,N−1]T as below Where M is the length of the TS, Nis the length of the OFDM data block, P=M+N presents the length of the TFT-OFDM symbol, Xi=[Xi,0Xi,1 ··· Xi,N−1]T Denotes the frequencydomain OFDM symbol, and xi =FNH Xi Being different from the time-domain PN sequence used inTDS-OFDM, the TS in TFT-OFDM could be any kind ofsequences with desirable specific features defined in the above two domain. Normally, the sequences with idealor good autocorrelation property are preferred for channelestimation.e.gThe constant amplitude with zero autocorrelation(CAZAC) sequence with constant envelop in both time andfrequency domains , or the PN sequences are used in TDS-OFDM. The TS having constant envelopein the frequency domain, i.e., ci =FHMCi, where Ci=[Ci,0Ci,1 ··· Ci,M−1]T with the entry |Ci,k| =c, and c is an arbitrary real number. For simplicity ,Ci ,k =±1is used throughout this paper. It can be proved that such TS with any length has perfect circular autocorrelation property, since the circular correlation theorem allows 71 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 defined by In the frequency domain, different from TDS-OFDM where all subcarriers are used to carry the useful data , TFTOFDM has Nd data subcarriers and Ngroup groups of binary phase-shift keying (BPSK) modulated pilots scattered over the signal bandwidth. Each pilot group has 2d+1pilots. The index set of the central pilots in the Ngroup pilot groups can be denoted by η={η0η1 ··· ηNgroup−1}, and the index set of all pilots is consequently presented by the Ψ={η0−dη0−d+1···η0+d···z ηNgroup−1−d···ηNgroup−1+d}. The pilot number is Np=Ngroup(2d+1), and N=Nd+Np. Although the frequency-domain pilots are very common in CPOFDM systems, the grouped pilots in TFT-OFDM are different from the block-type pilots or the comb-type pilots used in most CP-OFDM systems, e.g., the second generation digital terrestrial television broadcasting system (DVB-T2) and the next generation mobile wireless system called the long term evolution (LTE), TFT-OFDM requires much less pilots than CPOFDM. The discrete multipath channel during the ith TFTOFDM symbol at the time instant n(−M≤n≤N−1) can be modeled as hi,n =[hi,n,0hi,n,1 ··· hi,n,L−1] T of the maximum length L, where hi, n ,l denotes the coefficient of the l th path with the delay nl. Behind the cyclic prefix reconstruction of the received OFDM block has been accomplished (the hybrid domain cyclic prefix reconstruction method based on the well-known overlap and add (OLA) scheme in ZP-OFDM systems can be straightlyused.since TFT-OFDM is essentially equivalent to ZP-OFDM after removing the known TS at the receiver side), the received time domain OFDM block yi=[yi,0yi,1 ··· yi,N−1]T is (3) Where wiis the additive white Gaussian noise (AWGN) vector with zero mean and covariance of σ2IN, and the time-domain system matrix Hi is Using FFT to the above signal (3), we have the frequency domain OFDM block Yi=[Yi,0 Yi,1 ··· Yi,N−1]T as (5) Where Yi =FN yi, Wi =FNwi, and Gi is the N×N channel frequency response (CFR) matrix with the (p+1,q+1) th entry Gi,p,q being If the channel is time-invariant within each TFTOFDM symbol, the ICI coefficient Gi,p,q (p not = q) equals to zero, and Gi becomes a diagonal matrix. The proposed CS-based CE method firstly utilizes the PN-based correlation in the time domain to acquire the auxiliary channel information, and then the frequency-domain pilots are used for the final exact CIR estimation based on CS. 4.Exact CIR Estimation Using A-SP: The pilots can be extracted from the OFDM block after cyclicity reconstruction for the final accurate CE. Based on the basic idea of classical SP algorithm .The propose the A-SP algorithm, whereby the auxiliary channel information obtained.The areexploited to improve the CE performance and lower the computational complexity. The proposed A-SP algorithm is 72 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 described by pseudo code.Compared to the classical SP algorithm, the proposed A-SP algorithm has quite similar procedure, but differs from SP inthe following three aspects: 1) Initial Configuration: In the proposed A-SP scheme, by exploiting the obtained partial path delays T0, the initial approximation can be directly configured as T0 ← T0. 2) Significant Entry Identification:The S0 most significant entries unchanged, and identify the next S − S0 most significant ones instead. 3) Iteration Number: The required number of iterations is reduced from S − S0 in A-SP, so the computational complexity can be reduced. 5.Cyclicity Reconstruction of the OFDM Block: The cyclicity reconstruction of the OFDM block is achievedby firstly subtracting the IBI caused by the PN sequencefrom the received OFDM block, then adding the received PNsequence and finally subtracting the first part of linear convolution outputs between the PN sequence and channel . Thisprocess is based on the idea of OLA algorithm .The IBI caused by the PN sequence is obtained by computing the linear convolution between the local PN sequence and the estimated CIR obtained in the preceding symbol. Under the slow time-varying channels, which can be assumed in many wireless broadcasting systems , the estimated CIR obtained in the preceding symbol can be used for the IBI removal in the current symbol. In fact, the received PN sequence contains not only the useful part which is the IBI caused by the OFDM block, but also the useless part that is the linear convolution between the PN sequence and channel.Hence, the useless part should be removed after the receivedPN sequence is added to achieve the cyclicity reconstruction. 6.PerformanceAnalysis OFDM: Of Cs-Based TFT- embedded in TFT-OFDM is J = 36. The conventional TDS-OFDM scheme has the highest spectral efficiency, but the iterative interference cancellation isrequired, which results in high complexity and performanceloss. In the DPNOFDM scheme, the PN sequence is duplicated to avoid the interference from the preceding OFDMblock to the second PN sequence, but the spectral efficiency issignificantly reduced. In the proposed scheme, the embeddedpilots would some how reduce the spectral efficiency, but thepenalty is very small, since the proposed A-SP signal recovery algorithm only requires a very small number of observationsO Slog2 L S . In fact, for the most common broadcasting channels with six active paths, the number J = 36 ofthe embedded pilots is enough for good channel recovery performance.In the typical system configuration of M = 256 and N =4096 ,the spectral efficiency of the proposed CS-basedTFT-OFDM scheme is 93.29%, which is only 0.83% less thanthat of the conventional TDS-OFDM system.Theconstant 36symbol transmission parameter signaling (TPS) used in the practical DTMB systemscan be regarded as the pilots once after being successfullydetected , which indicates that even the negligible spectralefficiency loss can be avoided. B)CRLB of the Channel Estimator: Compared with the channel estimator in DPN-OFDM systems, where the best mean square error (MSE) performanceis σ 2 , the channel estimator based on A-SP can achieve muchbetter MSE performance, since S is much smaller than J, andthe boosted power A is usually larger than 1. The observation matrix T does not have orthogonal columns, the CRLB cannot be achieved by the practical channel estimator. However, due to the random positions of the pilots used in TFT-OFDM and the random locations of active paths of wireless channels, the matrix T has imperfect but approximate orthogonal columns. A). Spectral Efficiency: C).Computational Complexity: The spectral efficiency of different TDSOFDM schemes with the ideal OFDM system without anyoverhead . The length of the PN sequence is M = 256and the pilot number In the CS-based CE method, the M-point circular correlation could be efficiently implemented by M-point FFT, so the corresponding complexity is O Mlog2 (M) /2 . It 73 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 requires the complexity of O Mlog2 (M) /4 + 3M for the cyclicity reconstruction operation. In fact, the main computational burden of the proposed method is the A-SP algorithm used to acquire the actual path delays . Each iteration has the complexity of O J L + S2 , and the overall complexity of SP comprising S iterations is O JS L + S2 and S − S0 iterations are required by A-SP, since some of the locations of the significant taps have been detected already, the complexity of the proposed A-SP is reduced to O J (S − S0 ) L + S2 . So the complexity of A-SP is lower than that of SP. simulations.The typical six-tap ITU-VB channel model(S = 6, L = 152) is adopted for performance evaluation.Furthermore, the State Administration of Radio, Film, andTelevision 8 (SARFT-8) channel model (S = 6, L = 241) witha very strong echo path close to the GI length and the modified ITU-VB channel (S = 7, L = 303) with an extremelylong path delay exceeding the GI length are also adoptedto evaluate the system performance. 7.Simulation results This section investigates the performance of the CS-basedCE for TFT-OFDM under typical roadcasting channels. Thesignal bandwidth is 7.56 MHz locating at a central frequency of 760 MHz. The OFDM block length N is 4096,and the GI length M is 256. The low-density paritycheck(LDPC) code with code rate of 0.6 and code length of7488 in DTMB is adopted.The wellknown iterativedecoding algorithm called belief propagation (BP) is usedwith the maximum iteration number of 30.The modulation schemes 256 QAM for the static channel and 16QAM with a receiver velocity of 60 km/h are both considered to evaluate the support for UHDTV and mobile services,respectively. Fig.6:MSE performance comparison under the modified SARFT-8 channelwith the channel length larger than the GI length Fig: 5and 6 present the MSE performance comparison of theproposed scheme with the onventional DPN-OFDM and CS-based TDSOFDM schemes under three different channelswith different channel lengths. It can be seen from Fig. 5 thatunder the ITU-VB channel, the MSE performance of the proposed scheme enjoys a significant SNR gain of 4 dB and 10 Dbcompared to those of CS-based TDS-OFDM and DPNOFDM,respectively, when the target MSE of 10−3 is considered. Ifthe channel length L is fairly close to the GI length M, seethe SARFT-8 channel considered in Fig. 6, the MSE performance of the proposed scheme is 7.5 dB better than that ofDPNOFDM, while the recent CS-based TDS-OFDM cannotwork due to the reduced size of the IBI-free region. Fig.5: MSE performance comparison under the ITU-VB channel with thechannel length smaller than the GI length. The multipath channel parameters used for 74 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 Conclusion Fig.7 BER performance comparison under the ITU-VB channel . under the ITU-VB channel, the BER performance of the proposed scheme enjoys a significant Eb /N0 gain of about 1 dB and 2.5 dB compared with CSbased TDS-OFDM and DPN-OFDM, respectively, when the target BER of 10−4 is considered. This paper proposes a CS-based CE method for OFDM transmission scheme called TFT-OFDM, whereby the training information exists in both time and frequency domains. The corresponding joint time-frequency channel estimation utilizes the time domain TS without interference cancellation to estimate the channel path delays, while the channel path coefficients are acquired by using the pilot groups scattered within the OFDM symbol. The MSE performance of this method outperforms the conventional schemes and is close to the CRLB bysimultaneously exploiting the time-domain PN sequence andfrequencydomain pilots. Simulation results show that the proposed scheme has a good BER performance in both static andmobile scenarios and can well support the 256 QAM, especially when the maximum channel delay spread is fairly closeto or even larger than the GI length. Besides, by using the auxiliary channel information, the proposed ASP algorithm haslower complexity than the conventional SP algorithm. Thus,this scheme is expected to extend TDS-OFDM in the emerging UHDTV applications under SFN with long channel delayspread. Furthermore, for CP-OFDM system with time-domainpreamble or TS, this scheme can also be applied. REFERENCES Fig.8 BER performance comparison under the SARFT-8 channel Fig. 8 that under the SARFT-8 channel, the BER performance of the proposed scheme is about 2 dB better than that of the DPN-OFDM scheme, while the CS-based TDS-OFDM scheme cannot work due to the IBI-free region is severely ontaminated by the long channel 1. J. Wang, Z. Yang, C. Pan, and J. Song, “Iterative padding subtraction of the PN sequence for the TDS-OFDM over broadcast channels,” IEEE Trans. Consum. Electron., vol. 51, no. 11, pp. 1148–1152, Nov. 2005. 2. Z. Tang, R. Cannizzaro, G. Leus, and P. Banelli, “Pilotassisted time varying channel estimation for OFDM systems,” IEEE Trans. Signal Process, vol. 55, no.5, pp.2226–2238, May 2007. 3. J. Fu, J. Wang, J. Song, C. Pan, and Z. Yang, “A simplified equalization method for dual PN-sequence padding TDS-OFDM systems,” IEEE Trans. Broadcast., vol. 54, no. 4, pp. 825–830, Dec. 2008. 4. W. Dai and O. Milenkovic, “Subspace pursuit for compressive sensing signal reconstruction,” IEEE Trans. Inf. Theory, vol. 55, no. 5, pp. 2230–2249, May 2009. 5. L. He, F. Yang, C. Zhang, and Z. Wang, “Synchronization for TDSOFDM over multipath fading channels,” IEEE 75 All Rights Reserved © 2015 IJARTET ISSN 2394-3777 (Print) ISSN 2394-3785 (Online) Available online at www.ijartet.com International Journal of Advanced Research Trends in Engineering and Technology (IJARTET) Vol. II, Special Issue XXIII, March 2015 in association with FRANCIS XAVIER ENGINEERING COLLEGE, TIRUNELVELI DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN COMMUNICATION SYSTEMS AND TECHNOLOGIES (ICRACST’15) TH 25 MARCH 2015 Trans. Consum. Electron.,vol. 56, no. 4, pp. 2141–2147, Nov.2010. 6. L. Dai, Z. Wang, and S. Chen, “A novel uplink multiple access scheme based on TDS-FDMA,” IEEE Trans. Wireless Commun., vol. 10, no. 3, pp. 757–761, Mar. 2011. 7. L. Dai, Z. Wang, and Z. Yang, “Compressive sensing based time domain synchronous OFDM transmission for vehicular communications,” IEEE J. Sel. Areas Commun., vol. 31, no. 9, pp. 460–469, Sep. 2013. 8. Linglong Dai, Jintao Wang and ZhaochengWangTsinghua National Laboratory for Information Science and Technology, Tsinghua University, China “Time Domain Synchronous OFDM Based onSimultaneous MultiChannel Reconstruction’’. 9. J. Xiong, L. Gui, H. Liu, and P. Cheng, “On channel estimation andequalization in 2x1 MISO TDS-OFDM based terrestrial DTVsystems”IEEE Trans. Broadcast., vol. 58, no. 1, pp. 130–138, Mar. 2012. 10. K. Yan, F. Yang, C. Pan, and J. Song, “Reception quality predictionin a single frequency network for the DTMB standard,” IEEE Trans.Broadcast., vol. 58, no. 4, pp. 629– 636, Dec. 2012. 11. S. Li, J. Xiong, L. Gui, and Y. Xu, “A generalized analytical solution to channel estimation with intersymbol interference cancelation and cochannelinterference cancelation for single input single output/multiple input single output digital terrestrial multimedia broadcasting systems,”IEEE Trans. Broadcast., vol. 59, no. 1, pp. 116– 128, Mar. 2013. 12. B. Ai, J. Ge, and Y. Wang, “Symbol synchronization technique in COFDM systems,” IEEE Trans. Broadcast., vol. 50, no. 1, pp. 56–62, Mar. 2004. 76 All Rights Reserved © 2015 IJARTET
© Copyright 2024