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Anti-aliasing filters play an important role in analog front-end circuits, and their suitable design can improve the performance of digital audio broadcasting systems. In this paper, a Gm-C anti-aliasing filter based on carbon nanotube field effect transistors (CNTFETs) is proposed. Using CNTFETs provides low power consumption and appropriate frequency response. Simulation results show that these characteristics are widely dependent on the physical parameters of CNTFETs. The effects of chirality, the number of CNTs in each CNTFET, and distance of CNTs from each other on power consumption and frequency response are investigated. Among these parameters, the chirality and number of CNTs respectively have nonlinear and linear relationships with both power consumption and cutoff frequency. On the other hand, changing the distance between CNTs has the least effect on the output characteristics. Also, the output features of the filter for different gate oxides and channel lengths are studied. The overall result of the simulations demonstrates that the filters based on CNTFETs are promising candidates to be used in future nano-scale integrated circuits.

The single frequency network (SFN) is a popular solution in modern digital audio and television system networks for extending effective coverage, compared to its traditional single-transmitter counterpart. As benefits of this configuration appear to be obvious, this paper focuses on the exact analysis of so-called SFN gain&mdash, a quantitative effect of advantage in terms of the received signal strength. The investigations cover a statistical analysis of SFN gain values, obtained by means of computer simulations, with respect to the factors influencing the coverage, i.e., the protection level, the reception mode (fixed, portable, mobile), and the receiver location (outdoor, indoor). The analyses conclude with an observation that the most noteworthy contribution of the SFN gain is observed on the far edges of the networks, and the least one close to the transmitters. It is also observed that the highest values of the SFN gain can be expected in the fixed mode, while the protection level has the lowest impact.

China's Convergent Digital Radio (CDR) and Rus-sia's Real-time Audio Visual Information System (RAVIS) are two digital audio broadcasting systems in Frequency Modulation band. Due to the two countries' unique geographic locations and their long shared broader, the efficiency of both systems in the coexistence of the other is required to be evaluated. This paper discusses the compatibility of CDR and RAVIS by conducting a number of tests and demonstrating the working efficiency of both systems under interference of the other. In the tests, Carrier-to-Noise-Threshold (C/N) for RAVIS under different channel models were tested. Signal-to-interference ratio (S/I) of both systems under interference of the other are evaluated.

The article presents the issue of signal transmission in the Single Frequency Network SFN network that supports Digital Audio Broadcasting DAB+ digital radio. In the SFN network, the most important issue is the synchronization of transmitters, which is why it is necessary to ensure a stable connection between the multiplexer and the modulator. The paper proposes the use of the optimal, from the SFN point of view, transmission link, and also presents the results of using the Long Term Evolution LTE system as a transmission link that does not meet the requirements of the SFN network. For the proposed solution based on a radio-line, the results of measurements of delay and transmission speed were presented. Also measurements of signal delays in the real SFN network were presented, in which various methods of signal transmission between the multiplexer and transmitters were used.

OFDM stands for orthogonal frequency division multiplexing and is a form of multicarrier modulation (MCM) technique which divides the whole bandwidth into huge number of small sub-carriers. After this, each subcarrier is transmitted in parallel to attain increased data rates. Real data implementation of the proposed OFDM model has been simulated for image signal under AWGN channel. BER is calculated under different SNR values. The proposed work is done using MATLAB–Simulink tool.

The rapid development and implementation of wireless communication standards put increasing pressure on spectrum allocation, and therefore threaten the efficacy of radio astronomy. For example, digital audio broadcasting (DAB) is a wide-bandwidth broadcast technology that is now being implemented and has spectrum allocated in the L band. We demonstrate that standard narrowband subspace subtraction methods may provide insufficient suppression of such signals. We therefore propose two algorithms that take into account the non-narrowband nature of these signals. The first proposed algorithm is based on a flat-frequency-response model. The second is an approximation of the first that makes use of two frequency-shifted monochromatic sources (Zatman's model). An experimental demonstration of both proposed algorithms yielded an increase of approximately a factor six in bandwidth per channel that can be processed when compared to conventional narrowband techniques (for the same attenuation of the RFI signal). The performance of the two methods was identical for LOFAR station configurations with bandwidths between 763 Hz and 195 kHz. However, the model based on Zatman's algorithm required fewer operations (a speed-up of 1.3 was achieved). An equation is derived that gives the direction of arrival for a far-field non-narrowband signal that causes the greatest distortion of the visibilities. Another equation is derived for the appropriate frequency channel bandwidth at which to implement the proposed non-narrowband RFI mitigation algorithms.

This paper proposes an adaptive impedance matching subsystem, called self-structuring impedance matcher (SSIM), for in-vehicle digital audio broadcasting (DAB) applications. The goal of the SSIM is to make antennas originally aiming at other vehicular applications, such as a digital television (DTV, 470–894 MHz) and an interphone car radio (136–174 MHz), operate in the targeted DAB frequency band (170–240 MHz), thereby lowering the startup cost of DAB devices. The SSIM consists of a template of a matching circuit, a microprocessor, and a receiving-type sensor. The template uses a nonuniform microstrip line interconnected with relay switches. To enhance the dynamic range and reduce the insertion loss for the template simultaneously, this work employs a new design technique based on solving the mathematical programming problem of matching requirements. The resultant matching domain covers a large area of the Smith chart, although only five switches are used. Experimental results show that the SSIM successfully adapts an interphone/DTV antenna into a DAB receiving mode. The operational bandwidth meets the DAB specification, and the transducer gain is larger than −1.83 dB.

Orthogonal Frequency Division Multiplexing (OFDM) is a type of Multicarrier Modulation (MCM) technique in which entire bandwidth is divided into large number of small sub-carriers and each subcarrier is transmitted parallel to achieve higher data rates. It has various applications like Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB) and wireless LAN.OFDM technique is widely used in wireless communication system because of its very high data rate. The performance of FFT based OFDM system using Linear and cyclic channel coding and Constant Modulus Algorithm (CMA) equalizer is simulated using simulink model. The BER saving using the optimized proposed model with both linear and cyclic channel coding along with CMA equalizer is evaluated. The proposed work using cyclic channel coding with QPSK/QAM modulation and CMA as channel equalization under AWGN channel results in 52.6% and 96.3% BER reduction as compared to conventional OFDM model without channel coding, channel equalization and channel fading. So, CMA equalizer is used to enhance the performance of OFDM system.

On the basis of reconnaissance of the radiation source in the environment, the non-cooperative detection radar can realize the detection of the target by considering the direct wave of the radiation source and the scattering echo of the target signal to the radiation source. The non-cooperative detection radars have been developed the sources of illumination, including analog television signals, FM(Frequency Modulation) radio signals, digital audio broadcasting, digital video broadcasting, communication satellites and GPS(Global Positioning System) satellites. Because of the characteristics of silent reception, bistatic, and the wide range of the electromagnetic wave signal, the passive detection radar has the incomparable advantage to the conventional active radar. Considering the amount of calculation, the system usually adopts two-coordinate system, which will bring positioning error According to the flight characteristics of civil aircraft, this paper proposes an iteratively improved measurement accuracy method Tests show that the method achieves good results.

In this paper we propose usage of multiple antennas (antenna array) for improving reception of digital radio signal in mobile receiver. In contrast to currently used systems we propose to use more than 2-antennas (in MISO scheme) together with novel algorithm for elimination of direct Doppler effect causing inter-carrier (ICI) interference in mobile systems. Some of the antenna will have directional characteristics that allow estimating the direction and speed of vehicular receiver. This feature has large impact on digital reception systems moving at high speeds. Performance of our solutions was evaluated in car entertainment systems for Digital Audio Broadcasting (DAB) radio and HD radio. Obtained results showed lower BER in the same conditions in comparison to the standard dual antenna system with Maximum Rate Combining (MRC) enabled.

Orthogonal frequency division multiplex (OFDM) is used in several modern wireless systems, for example in the fourth generation mobile system LTE (long term evolution), the wireless local area network (WLAN) standard IEEE 802.11, digital audio broadcasting (DAB) and digital video broadcasting (DVB). OFDM has also recently been included in the standard for the fifth generation mobile system, 5G.In this work, we analyze the vulnerability of 5G NR to different types of continuous wave (CW) interference, both a single CW signal or several synchronized CW signals. The analysed system includes OFDM and error correction by LDPC codes, with parameters chosen to resemble those of the 5G NR release 15 standard. An important conclusion of this work is that the 5G NR system is significantly more sensitive to CW interference than to white Gaussian noise. To improve the robustness against CW interference, different types of limiters on the received signal are also evaluated. Limiters in the frequency domain are shown to mitigate the impact from a single CW signal significantly. For an interfering signal consisting of several CW signals, a limiter in the time domain can reduce the impact of the interference signal so that its impact is below that of Gaussian noise with the same power.

Digital Audio Broadcasting (DAB) is a widely used terrestrial audio broadcast transmission system. DAB employs Orthogonal Frequency-Division Multiplexing which allows the operation in a Single Frequency Network (SFN). SFNs are beneficial for the distribution of services in large areas, but do not support local services, i.e. different services from different transmitters, without distortion. However, some audio service providers rely on local services. A Local Service Insertion technique for DAB SFNs that supports existing receivers was developed, tested and presented in a field trial in Braunschweig, Germany. The results showed some co-channel interference between local services for existing receivers that use conventional differential detection (CDD). In this paper, we investigate an iterative decision-directed differential detection technique with channel equalization to combat the remaining co-channel interference. An increase in robustness against co-channel interference of about 3 dB is found in comparison to CDD.

$%&'()*+,-./0 1 10234 5, 6 78 9 :1 ; >?@* 0AB: CD>? EFG H( 5 *I DAB(Digital Audio Broadcasting)I : JHK, *:ATSC(Advanced Television Systems Committee)GLM&NI O. J (P=>>?/O >?QRST &' U*VW XCY, *&Z[ =\ U , ]^_`EFG 9Rabc? >?de*fbg Ghi*j kHlV O.AbstractIn this paper, Method for the phase distortion compensation timing offset and DC eliminator for the pilot component estimation and removal, transmitted and received signal correlation in the delay scheme DAB interference cancellation based on the same channel for using for estimating the feedback signal based on a between for removal for the timing offset compensation It proposes a repeater. This was applied to the ATSC system. The on-channel repeater of the proposed interference cancellation based on the interference removing capability is improved in interference signal is 20dB greater than the primary transmission signal environment via the return channel estimation and improve performance RFP. Accordingly, it was confirmed by simulation that good signal is sent out with the improvement of the ability of the repeater.Keywords : ATSC system, on-channel repeater, interference cancellation

Orthogonal Frequency Division Multiplexing (OFDM) has great demand in wideband digital communication. It encodes the data on multiple carrier frequencies. Its application areas are digital audio broadcasting and high definition television, wireless network, 4G mobile communications. Due to its great advantages like it provides high spectral efficiency, remove inter symbol interference, reduced nonlinear distortion it is widely used for communication purpose. Major problem of this scheme is high Peak to Average Power Ratio (PAPR). To overcome this problem i.e. PAPR, here in this paper we figure out different reduction techniques, there pros and cons and also find Selective Mapping (SLM) is better technique due to its several advantages with reduced PAPR and better Bit Error Rate (BER) which is discussed further in this paper.

Orthogonal frequency division multiplexing is a type of multicarrier modulation technique which is used in wireless communication. OFDM can be used in various wireless and wired application such Digital audio broadcasting, digital video broadcasting & wireless LAN. The Performance of OFDM system depends on various parameters such as using different transform, different modulation and by putting various channel coding. In this paper OFDM system is modeled by using different transform (DWT/FFT), different modulation (BPSK, QPSK, QAM) and different channel coding (Linear / Cyclic block codes) for AWGN channel. The performance parameter is calculated as Bit error rate (BER) for various transform/modulation/channel coding based OFDM systems. MATLAB Simulink tool is used to calculate the bit error rate (BER).

Orthogonal frequency division multiplexing (OFDM) has become an indispensable part of waveform generation in wideband digital communication since its first appearance in digital audio broadcasting (DAB) in Europe in 1980s, and it is indeed in use. As has been seen, the OFDM based waveforms work well with time division duplex operation in new radio (NR) systems in 5G systems, supporting delay-sensitive applications, high spectral efficiency, massive multiple input multiple output (MIMO) compatibility, and ever-larger bandwidth signals, which has demonstrated successful commercial implementation for 5G downlinks and uplinks up to 256-QAM modulation schemes. However, the OFDM waveforms suffer from high peak to average power ratio (PAPR), which is not desired by system designers as they want RF power amplifiers (PAs) to operate with high efficiency. Although NR offers some options for maintaining the efficiency and spectral demand, such as cyclic prefix based (CP-OFDM), and discrete Fourier transform spread based (DFT-S-OFDM) schemes, which have limiting effects on PAPR, the PAPR is still as high as 13 dB. This value increases when the bandwidth is increased. Moreover, in LTE-Advance and 5G systems, in order to increase the bandwidth, and data-rate, carrier aggregation technology is used which increases the PAPR the same way that bandwidth increment does, therefore, it is essential to employ PAPR reduction in signal processing stage before passing the signal to PA. In this paper, we investigate the performance of an innovative peak shrinking and interpolation (PSI) technique for reducing peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) based signals at waveform generation stage. The main idea behind the PSI technique is to extract high peaks, scale them down, and interpolate them back into the signal. It is shown that PSI technique is a possible candidate for reducing PAPR without compromising on computational complexity, compatible for existing and future telecommunication systems such as 4G, 5G, and beyond. In this paper, the PSI technique is tested with variety of signals in terms of inverse fast Fourier transform (IFFT) length, type of the signal modulation, and applications. Additional work has been carried out to compare the proposed technique with other promising PAPR reduction techniques. This paper further validates the PSI technique through experimental measurement with a power amplifier (PA) test bench and achieves an adjacent channel power ratio (ACPR) of less than &ndash, 55 dBc. Results showed improvement in output power of PA versus given input power, and furthermore, the error vector magnitude (EVM) of less than 1 % was achieved when comparing of the signal after and before modification by the PSI technique.

This paper introduces the research significance and the current development situation of CE-OFDM firstly, and then introduces the system structure of the CE-OFDM which is based on FM modulation, and each module are introduced in details by comparing with OFDM system. Then the simulation is conducted with MATLAB and results are analyzed. This paper also compares with CE-OFDM system which was put by Steve C. Thompson, to confirm the feasibility of the system in this paper finally.

During 2017, digital audio broadcasting (DAB) replaces frequency modulation (FM) broadcasting and becomes the only technology for national terrestrial audio broadcasting services in Norway. As Norway is the first country that replaces FM completely with DAB, it is of great importance to measure the signal strength of such a technology in massive deployments and to tune a simulation model as a reference for future studies. Therefore, field measurements of received signal strength are carried out in a typical Norwegian area in this work. Based on the data obtained from the measurements, a simulator with a recent empirical propagation model, namely, ITU-R P.1546-5, has been calibrated. The findings, in short, suggest that different clutter codes and attenuation parameters have to be tuned according to the measurement results in order to increase the precision of the simulation model. By properly tuning the parameters in the model, the precision has increased 91.7% compared with the default configuration. In addition, the tuned model is validated through another field measurement in a different area and obtains an increased precision of 72.9%.

This chapter is devoted to OFDM fundamentals and applications to wireless and optical communications. The chapter starts with the basic of OFDM including the generation of OFDM signal by inverse FFT. After that several basic manipulations on OFDM symbols, required to deal with multipath effects in wireless communications and dispersion effects in fiber-optics communications, including guard time and cyclic extension as well as the windowing operation, are described. Next, the bandwidth efficiency of OFDM is discussed. The next topic in the chapter is devoted to the OFDM system design, description of basic OFDM blocks, and OFDM-based parallel channel decomposition, including multipath fading radio and dispersion-dominated channels decomposition. Following the description of coherent optical OFDM (CO-OFDM) principles, the basic estimation and compensation steps, common to both wireless and optical communication systems, are described including DFT windowing, frequency synchronization, phase estimation, and channel estimation. Regarding the channel estimation, both pilot-aided and data-aided channel estimation techniques are described. Following the differential detection in OFDM description, the focus is on various applications of OFDM in wireless communications including digital audio broadcasting (DAB), digital video broadcasting (DVB), WiFi, LTE, WiMAX, and ultra-wideband communication (UWB). Next, optical OFDM applications are discussed starting with description of basic OFDM system types such as CO-OFDM and direct-detection optical OFDM (DDO-OFDM) systems. Regarding the high-speed spectrally efficient CO-OFDM systems, the polarization-division multiplexed OFDM systems and OFDM-based superchannel optical transmission systems are described. Before the concluding remarks, the application of OFDM in multimode fiber links is described.

We have witnessed a drastic increase in Orthogonal Frequency Division Multiplexing (OFDM) in optical community in recent years. OFDM is a type of signal modulation. OFDM divides high data rate modulating stream into many slow modulated narrowband subcarriers. Thus, it is less sensitive to frequency fading. OFDM is used for many of the latest wireless and telecommunications. OFDM technique is used in Digital Audio Broadcasting (DAB), HDTV, Wireless LAN. In OFDM the spectrum of individual subcarrier is overlapped with minimum frequency spacing, which is carefully designed so that each subcarrier is orthogonal to each other. In the 1980s, OFDM was studied for high speed modems digital mobile communication, and high recording. This paper deals with the Review of optical OFDM.

Current broadcast systems make use of either single frequency networks (SFNs) or multifrequency networks (MFNs) to distribute content. However, neither of the topologies is efficient to distribute both global and local content at the same time. While SFNs are ideal for delivering global content in a frequency- and power-efficient way, MFNs are well-suited to deliver local content to the desired reception areas. This paper describes a technique to allow local service insertion (LSI) in Digital Audio Broadcasting (DAB) SFNs. DAB has been in use for several years around the world. Proposals for LSI have been made before. However, those considerations focused on the transmission modes (TMs) II and III, which are no more supported in the current version of the DAB standard. Another approach is the use of small power transmitters resulting in a limited coverage area. Differential modulation makes it difficult to introduce local services into an SFN. The technique presented in this paper uses an artificial phase reference symbol consistent with differential modulation. Furthermore, this approach is compatible with TM I and supports existing DAB receivers. The proposed LSI technique is described in this paper and analyzed in terms of requirements for the services. Signal-to-noise ratio requirements are also evaluated.

This paper deals with a study of a special coexistence scenario that can occur between Digital Audio Broadcasting (DAB) and Digital Video Broadcasting-Satellite (DVB-S/S2) systems in a common radio frequency (RF) band. In this situation, the DAB is an interferer system, whereas the DVB-S/S2 is a victim system. An experimental workspace was realized to emulate and explore such a scenario. To evaluate a performance of the affected DVB-S/S2 signal, a bit and modulation error ratios (BER and MER) are used, respectively. Results of measurements, dependencies of these error values on a frequency shift between central carriers of both systems, and on a signal level difference of both RF signals are presented. Finally, results are analyzed and discussed in details.

Multicarrier communication (MCM) place a major role in wireless and wired communication. The multicarrier communication have more spectral efficiency and less noise effect compare with single carrier communication. One of the major MCM technique is orthogonal frequency division multiplexing (OFDM). The Main application of OFDM in wireless communication like WCDMA, LTE Digital Video broadcasting, Digital Audio Broadcasting, Wireless broadband communication and ADSL etc. The main disadvantage of OFDM technique is peak to average power ratio (PAPR). The PAPR reduction is one of the major problem in OFDM. To reduce PAPR there are various algorithms are available like SLM, Coding, and PTS etc. In PTS also different type of algorithms are available. The Adjacent portioning PTS is one of the advanced algorithm which is used for reducing PAPR. Adjacent portioning with Partial transmit sequence (AP-(PTS) aim to reduce the PAPR of OFDM signal. The PTS technique is one of the most promising technique to reduce PAPR. In this paper gives an idea to implement adjacent partition PTS with turbo coding for the better performance of the OFDM. Analysis of PAPR with PTS and without PTS is done and the reduction of PAPR is occurred by using this technique. Analysis of the PAPR reduction by using this technique with turbo coding is done by implementing AP-PTS with turbo coding in Simulink. By using AP-PTS with turbo coding almost 3.5dB PAPR reduction can be achieved.

The advance of wireless communications brings in various schemes of wireless digital communication technology. Analog communication and broadcasting services convert into digital services in many countries. The IBOC (In-Band On-Channel) system has been developed to work in the same band with the conventional analog radio and broadcasting digital signal simultaneously. HDR (HD-Radio) standard of IBOC (In-Band-On-Channel) can use coherent demodulation using pilot sub-carriers. In this paper, the performance of HD radio system is evaluated. To contribute to decision of digital radio standard and design of digital radio transmission network, the simulation results will give a help.

This paper describes a simple delay diversity technique for terrestrial digital multimedia broadcasting (T-DMB) and digital audio broadcasting in a single-frequency network (SFN). For the diversity technique, a delay diversity scheme is adopted. In the delay diversity scheme, a non-delayed signal is transmitted in the first antenna, and delayed versions of the signal are transmitted in each additional antenna. For an SFN environment with multiple transmitters, delay diversity can be executed by controlling the emission times of the transmitters. This SFN delay diversity scheme does not require any hardware changes in either the transmitter or receiver, and perfect backward compatibility can be acquired. To evaluate the performance improvement, laboratory tests are executed with various types of commercial T-DMB receivers as well as a measurement receiver. The improvement in the bit error rate performance is evaluated using a measurement receiver, and an improvement of the threshold of visibility value is evaluated for commercial receivers. Test results show that the T-DMB system can obtain diversity gain using the described technique.

This paper depicts the field trials and results for in-band digital radio technologies in Korea. For the in-band methods, HD Radio and DRM+ are considered. In HD Radio, MP3 hybrid mode and MP5 all digital modes are selected, and 4-QAM and 16-QAM are selected for DRM+. To evaluate the practical performance of each technology, system parameters and received electric field strength are evaluated in various test routes and environments. In the field trial, listening tests are also executed by test staffs, and the results of listening tests are analyzed and compared with results of system parameters. Since the trials consider various practical reception environments, the test results can be used as references for decision of digital radio standard.

The DRM+ (Digital Radio Mondiale) system is the extension up to 300 MHz of the DRM digital radio broadcasting system. During 2010 three different trials were conducted in Brazil with DRM+ system in VHF band II (popularly called FM band). These trials were defined to have a big, medium and small coverage area for big, local and community broadcasters. For this purpose, different transmission powers were used. The transmission was done with only DRM signal in low power trial. In the high and medium power trials the transmission was done in “combined mode”, that is, the FM and DRM+ signals were transmitted in adjacent channels from the same transmission site. In this paper the results of these trials are explained and compared with theoretical values.

A surface-acoustic-wave-less first folded-conversion and second down-conversion receiver for the AM/FM/digital radio mondiale (DRM)/digital audio broadcasting (DAB) radio standards is presented. This architecture is more suitable for broadcasting radio with ultra-narrow signal bandwidth since it relaxes the requirement on the local area (LO) generator by decreasing its tuning range. To reduce the blockers and out-of-band (OB) interferers, current amplifying and polyphase filters are introduced simultaneously. An inverter-based switched capacitor array technique is proposed in voltage-controlled oscillator (VCO) design to isolate the noise from the substrate. With a single VCO, the receiver can cover the frequency range from 100 kHz to 1.5 GHz. Without the RF pre-filters, the in-band ${\rm IIP}_{3}$ is 1.5 dBm, and the OB ${\rm IIP}_{3}$ is up to 17.4 dBm. The LO phase noise in the worst case is $-$ 119 dBc/Hz@1 MHz. The chip is fabricated in a 0.18- $\mu{\hbox{m}}$ CMOS technology, and mounted on a QFN package. It consumes only 86.4 mW under 1.8-V supply. To our best knowledge, this is first receiver reported thus far that supports all four AM/FM/DRM/DAB standards.

This paper depicts the digital radio test bed design and performance evaluation for digital audio broadcasting, DAB+, and terrestrial digital multimedia broadcasting audio systems that are representative digital radio broadcasting standards operating in band III (out-of-band). We consider a laboratory trial to measure the performance of each digital radio system. The existing broadcasting measurement systems have some limitations, such as the small number of available measurement items and broadcasting systems. However, the introduced test bed can cover above representative three digital radio systems and measure various performance parameters. This paper minutely describes not only the test bed designs but also various test results according to the measurement items. Therefore, this paper can help select an appropriate digital radio standard.

In this paper analysis of Digital audio broadcasting on its four different modes have been performed. All the possible four modes have been executed and simulated on SIMULINK platform under different types of modulation schemes and channels. This paper is trying to develop a novel scheme of low cost, complexity wise reduced communication model for open air performance analysis. Thus the paper implements a novel method for the purpose of quality improvement in the communication equipment improvement using DAB. The results that have been performed on different types of channels are additive white Gaussian noise, Rayleigh and Rician fading channels. Similarly different modulation schemes in the model for example BPSK, QPSK, 16 QAM on different channels has been done. Of all the different types of channels in MATLAB & SIMULINK software for which a complete detailed table analysis has been done has found that of all the possible four modes the fourth mode has outperformed with good level of BER performance ranging between 20% to 22%. This paper has shown that with QPSK and AWGN Rayleigh channel mode 4 has proved to be the best working mode.

Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier multiplexing technique used in many applications such as Wireless Local Area Network (WLAN), Digital Audio Broadcasting Terrestrial (DAB-T) and Long Term Evolution (LTE). It provides high efficiency and low data loss in multipath environment hence there is a need for suitable modulation technique. Different modulation techniques in OFDM give different Bit Error Rate (BER) performance and spectral efficiency. Moreover Even after modulation the output of Inverse Fast Fourier Transform (IFFT) gives large Peak Amplitude Power Ratio (PAPR) which poses a problem in amplifier efficiency and complexity in analog to digital converters. This paper aims at finding a suitable modulation scheme and efficient technique to reduce PAPR in OFDM, based on BER and bandwidth. Algorithms are implemented using MATLAB for different modulation schemes over AWGN, Rayleigh and Rician channel for WLAN application with 52 subcarriers. Random bits are generated such that there are 16 symbols, each symbol having 52 bits. In AWGN for 3db SNR 64-QAM gives BER of 0.23 and to achieve same BER, 64-PSK requires 25db SNR. Rician channel gives better performance compared to Rayleigh, where BER is 0.2965 for Rayleigh and 0.2714 for Rician thereby reducing it by 0.02. Using wavelet transform PAPR is reduced to 62% of that using FFT.

In this paper, the possibility and necessity of the digital broadcasting propulsion in AM and FM is presented based on DRM and DRM+ transmission modes, They are the members of series technological family in digital radio development. As the frequency utilization, the application of DRM+ is flexible in any mode such as IN-BAND or OUT-OF-BAND. When the digital audio broadcasting is planned at LOW-VHF bandwidth such as TV channel No.5 and NO.6 being adjacent to FM band and OUT-Of-BAND DRM+ technology is applied, there is no collision and jamming. Particularly, in the IN-BAND Hybrid mode, it is mentioned that there was the difficulty problem for multiple SFN transmitters uses. Not like the IN-BAND mode the OUT-OF-BAND mode lets multiple transmitters, because neighbor transmitters do not interfere each other. Digital transmitter can be combined with the existing FM transmitter. The intensity of power and size of area can be easily determined according to local broadcasters` condition. And the OUT-OF-BAND mode is advantageous for AM/FM integration in digital radio receiver manufacturing, which makes the conversion schedule much shorter.

Frequency is an important parameter for the operation and control of power systems. One novel application of frequency measurements involves using this information to authenticate a digital audio/video recording presented as forensic evidence in legal proceedings. To apply this technique, called the electrical network frequency (ENF) criterion, both a reference frequency database and an accurate frequency estimation method are required. This paper briefly introduces a wide-area frequency monitoring network (FNET) as the reference frequency database and analyzes statistical features of frequency of the four North American interconnections in terms of different time scales. Combined with digital filtering and a three-sample interpolation, the short-time Fourier transform (STFT) is adjusted to estimate the ENF embedded in digital audio recordings. A procedure of using the ENF criterion, ranging from signal preprocessing to ENF estimation and reference frequency database matching, is then proposed. Further, oscillator error of the digital recording device is considered and an iterative error correction method is given to assist with the frequency database matching. Factors which influence the accuracy of frequency estimation, such as parameter selections of the STFT and signal-to-noise ratio, are also discussed. Test results show that the procedure is capable of performing digital audio authentication.

As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency division multiplexing (OFDM) is extensively used in modern digital television terrestrial broadcasting (DTTB) systems to support high performance bandwidth-efficient multimedia services. Chinese digital television terrestrial broadcasting standard recommends three kinds of Frame Head mode with PN420/PN595/PN945 as training sequences for the time domain synchronous OFDM (TDS-OFDM) based Digital Terrestrial Multimedia Broadcasting (DTMB) systems. At the receiver side, Frame Head mode detection and symbol detection should be done before subsequent synchronization and channel estimation. In this paper, a Frame Head mode detection and symbol detection scheme robust to carrier frequency offset is proposed for the TDS-OFDM based DTMB systems. Performance studies under different channel situations are used to verify the efficiency of the proposed scheme.

This paper focuses on the channel estimation techniques that are based on the block-type pilot arrangement. Once we establish reliable and practical channel estimation schemes for this type of pilot arrangement. In wireless OFDM transmission using pilot carriers and compare the bit error rate performance by using MMSE and LSE algorithms. Thus comb type pilots provide better resistance to fast fading channels. Also comb type pilot arrangement is sensitive to frequency when comparing to block type arrangement. “Channel Estimation Using LS and MMSE Estimators” Shakuntala Chouhan Contract Lecturer Department of Bio-Medical Engineering, Samrat Ashok Technological Institute Vidisha(M.P.) Shalu.chouhan5@gmail.com subject: Engineering AbstractThis paper focuses on the channel estimation techniques that are based on the block-type pilot arrangement. Once we establish reliable and practical channel estimation schemes for this type of pilot arrangement. In wireless OFDM transmission using pilot carriers and compare the bit error rate performance by using MMSE and LSE algorithms. Thus comb type pilots provide better resistance to fast fading channels. Also comb type pilot arrangement is sensitive to frequency when comparing to block type arrangement. This paper focuses on the channel estimation techniques that are based on the block-type pilot arrangement. Once we establish reliable and practical channel estimation schemes for this type of pilot arrangement. In wireless OFDM transmission using pilot carriers and compare the bit error rate performance by using MMSE and LSE algorithms. Thus comb type pilots provide better resistance to fast fading channels. Also comb type pilot arrangement is sensitive to frequency when comparing to block type arrangement. Key WordsOFDM; channel estimation; pilot based channel estimation INTRODUCTION Multimedia wireless services require high data-rate transmission over mobile radio channels. Orthogonal Frequency Division Multiplexing (OFDM) is widely considered as a promising choice for future wireless communications systems due to its high-data-rate transmission capability with high bandwidth efficiency. In OFDM, the entire channel is divided into many narrow sub-channels, converting a frequencyselective channel into a collection of frequency-flat channels. Moreover, inter-symbol interference (ISI) is avoided by the use of cyclic prefix (CP), which is achieved by extending an OFDM symbol with some portion of its head or tail [1]. In fact, OFDM has been adopted in digital audio broadcasting (DAB), digital video broadcasting (DVB), digital subscriber line (DSL), and wireless local area network (WLAN) standards such as the IEEE 802.11a/b/g/n [2-5]. It has also been adopted for wireless broadband access standards such as the IEEE 802.16e, and as the core technique for the fourth-generation (4G) wireless mobile Communications [6]. To eliminate the need for channel estimation and tracking, differential phase-shift keying (DPSK) can be used in OFDM systems. However, this result in a 3 dB loss in signalto-noise ratio (SNR) compared with coherent demodulation such as phase-shift keying (PSK) [7].The performance of OFDM systems can be improved by allowing for coherent demodulation when an accurate channel estimation technique is used. CHANNEL ESTIMATION IN OFDM SYSTEMS Channel estimation techniques for OFDM systems can be grouped into two categories: blind and nonblind. The blind channel estimation method exploits the statistical behavior of the received signals, while the non-blind channel estimation method utilizes some or all portions of the transmitted signals, i.e., pilot tones or training sequences, which are available to the receiver to be used for the channel estimation. BLOCK TYPE In this case pilots are inserted in a dense fashion in a few chosen symbols (typically the preamble symbol in most standards) with the following symbols running pilot-free. The pilot-dense symbols are expected to yield excellent channel estimates which are then, typically fed in to a channel tracker, which yields estimates on the pilot-less symbols. This paradigm is often termed semi-blind method of channel estimation. Clearly, the temporal spacing it between two consecutive pilot-rich symbols is limited by the Doppler spread of the environment. Hence, this type of pilot arrangement is often seen in static and lowDoppler environments such as wire-line transmissions or fixed wireless communication systems [13]. COMB TYPE Contrary to the block-type case, specific sub-carriers are chosen over which pilots are inserted in every symbol. This allows for simple 1-D (frequency domain) interpolation of the channel at the non-pilot locations and is suited for vehicular and high-Doppler environments. The frequency spacing of pilots DDDDffffin this case limits the maximum delay spread of the channel ττττmmmmmmmmmmmm. Practically, we see that an OFDM frame is peppered with pilots in a pattern which achieves a

Radio broadcasting technology in this era of compact disc is expected to deliver high quality audio programmes in mobile environment. The Eureka-147 Digital Audio Broadcasting (DAB) system with coded OFDM technology accomplish this demand by making receivers highly robust against effects of multipath fading environment. In this paper, we have analyzed the performance of DAB system conforming to the parameters established by the ETSI (EN 300 401) using time and frequency interleaving, concatenated Bose-Chaudhuri-Hocquenghem coding and convolutional coding method in different transmission channels. The results show that concatenated channel coding improves the system performance compared to convolutional coding.

A novel low-loss image-reject mixer (IRM) using the source follower isolation method for digital radio mondiale/digital audio broadcasting applications is presented. It is based on double-quadrature mixers (DQMs) and passive polyphase filters (PPFs). The DQM is designed with four passive CMOS mixers. A source follower is inserted between the RF PPF and DQM to decrease the conversion loss of the IRM. Compared with the traditional isolation method, the source follower isolation method shows much higher on-resistance while looking into the RF port of the mixer; meanwhile, the chip area will be greatly decreased. This chip is fabricated in a 0.18-μm CMOS technology. The total conversion loss is 10.5 dB, and the conversion loss per stage of PPFs is 2.1 dB on average. The image-reject ratio is larger than 40 dB in the bandwidth of 1.536 MHz without trimming and calibration. The PldB gain compression point is 7.6 dBm. The chip core area is 1.1 × 1.3 mm2.

Digital Audio Broadcasting (DAB) receiver requires fast Automatic Gain Control (AGC) to compensate the strength loss due to the multipath propagation in mobile receiving condition. But fast AGC could also incorrectly amplify DAB's null symbol and the following phase reference symbol to cause the synchronization problem. In this paper, we mathematically analyze the AGC circuit under a Rayleigh fading channel and give the basic rule to generate the AGC feedback voltage. Then a fast and high accuracy AGC algorithm with least affection on the DAB null symbol is proposed. The algorithm is simplified to have only add, shift and compare operations, making it easy for hardware and software implementation. Finally the algorithm is simulated and verified on Field Program Gate Array (FPGA) device. The test results show that the proposed AGC algorithm can be settled within 0.5 ms, and keep the received signal stable at a moving speed from stationary to over 120 km/h, both in city and suburban area. The algorithm and the analysis method can also be used for AGC design in other wireless systems.

The 26 MHz band is currently allocated for international broadcasting by means of the ionospheric propagation. However, sky waves are strongly dependent on the ionosphere conditions and signal reception is not always possible. As a consequence, this HF frequency range is scarcely utilized and an optimization of its use is required. The DRM (Digital Radio Mondiale) standard provides enough robustness to enable reliable audio reception taking advantage of the ground wave propagation at these frequencies. According to this, local coverage is viable in this part of the spectrum, as proved the field trials and studies carried out in the last years. Nevertheless, it is still necessary to establish the general guidelines for the set up and consolidation of the corresponding digital networks. Thus, the planning factors and procedures for digital local broadcasting services in the 26 MHz band are defined in this paper, along with reference parameter values and recommended system configurations for this new application.

This paper investigates the network deployment of single frequency networks (SFN) based on OFDM schemes that are standardized for terrestrial broadcasting systems, for digital audio broadcasting (DAB) and for digital video broadcasting (DVB) systems. The concept of green network planning is presented. The term `green' refers to low carbon, energy efficiency and low exposure to radiation, parameters important for the sustainable growth. For the purpose of our investigation a mountainous area of Northern Greece is examined, that is described by a digital terrain elevation model (DTEM) and field computations are based on multi shape slope uniform theory of diffraction (UTD) technique. A genetic algorithm (GA) optimization method is developed for the network planning purposes. A comparison between various planning strategies is presented. It is shown that great CO2 reductions, cost savings and low exposure to radiation can be achieved when the network planning considers a `green' strategy.

In this paper, we propose an improved sampling frequency offset (SFO) estimation scheme for orthogonal frequency division multiplexing (OFDM) based digital radio mondiale (DRM) broadcasting systems. To demonstrate the performance of the proposed frequency estimator, analytical expression of the mean square error (MSE) is derived and performances are compared with conventional pilot-assisted estimators. Based on the simulation and theoretical analysis, our proposed estimator shows an improved estimation performance compared to the conventional estimators.

Orthogonal frequency division multiplexing (OFDM), the multicarrier modulation technique with high bandwidth efficiency and robustness against multipath fading, is used in several high-speed broadband communication systems including digital video broadcasting (DVB), digital audio broadcasting (DAB), asymmetric digital subscriber line (ADSL), wireless local area network (WLAN IEEE 802.11a,g), high performance radio local area network (HIPERLAN 2), and worldwide interoperability for microwave access (WiMAX IEEE 802.16). However, the transmit signal in OFDM system has a high peak-to-average power ratio (PAPR), one of the major drawbacks of multicarrier transmission, and therefore high dynamic range is required in both the digital to analog converter (DAC) and the power amplifier (PA) for proper operation. Otherwise, the nonlinearities of PA cause out-of-band distortion and increase in bit error rate (BER). Therefore, the reduction in PAPR in OFDM system is desirable in order to obtain power efficiency and increase BER performance. In this paper, a new parametric PAPR reduction technique, L"2-by-3 transform from sliding norm transform (SNT) family is proposed. Based on its parameter, a significant PAPR reduction is obtained. This paper presents the analysis of power saving and computational complexity of the proposed method L"2-by-3 and comparison to two other methods; selected mapping and partial transmit sequence.

This paper describes the bit error rate (BER) performance of the Enhanced Packet Mode (EPM) of the Eureka 147 Digital Audio Broadcast (DAB) system in a mobile environment. The BER performance of DAB-EPM is characterized by computer simulations in frequency selective (typical case) and flat faded (worst case) mobile channels. For each of these channels, simulations are performed at vehicle speeds ranging from very slow (walking speed) to very fast (high speed trains). Simulation results show that, in typical frequency selective mobile environments, the target BER of 10 8 required to deliver adequate packet data service via the EPM is achieved at Carrier to Noise Ratio (C/N) values smaller than the target value of 14 dB used in coverage and frequency planning at most of the vehicle speeds tested. Moreover, the coverage area of packet data services is equivalent to the coverage of audio services delivered with the MPEG Layer 2 audio codec and the Unequal Error Protection Level 3 of DAB.

A number of mechanisms can result in the generation of spurious tones in Orthogonal Frequency Division Multiplexing (OFDM) receivers. In this work we determine the Signal-to-Noise-Ratio (SNR) degradation at the output of the Fast-Fourier-Transform (FFT) block and evaluate the performance of a Digital Audio Broadcasting (DAB) receiver in the presence of such tonal interference. We show that the degradation varies with the central frequency of the interference and demonstrate that relatively weak spurious tones can compromise the performance of a DAB receiver. We provide specific evaluations of the severity of the above effect for all possible DAB systems parameterizations and evaluate the permissible levels of spurious tones in such systems. It is shown that for DAB EEP Mode A protection level 4, tonal interference of 14 dB lower than the signal can compromise the receiver performance.

Terrestrial or Handheld Digital Video Broadcasting (DVB-T/H) and Terrestrial Digital Multimedia Broadcasting (T-DMB) are two popular broadcasting standards that enable digital television transmissions to handheld receivers. This paper presents a comprehensive performance comparison between the physical layers of DVB-T/H and T-DMB when employed for mobile communications. By exploiting a recently proposed fast simulation model, we assess the BER of the two coded OFDM systems in several realistic scenarios, taking into account Rayleigh and Rice channels, different mobile speeds, inner and outer channel coding, channel estimation, and one or two receive antennas. Our comparison shows that the DVB-T/H physical layer performance highly depends on the delay spread of the channel, whereas T-DMB is less sensitive to the frequency selectivity of the channel. As a result, DVB-T/H yields better performance than T-DMB in typical Rayleigh channels with significant delay spread. On the contrary, at high SNR, T-DMB outperforms DVB-T/H in Rice channels with low delay spread. As a side result, we show the performance improvement of DVB-H produced by MPE-FEC at the data link layer.

After coarse synchronization in orthogonal frequency division multiplexing (OFDM) systems, there might still be a residual frequency offset (RFO) and a sampling clock frequency offset (SFO), which seriously degrade the performance of the systems. This paper proposes a simple way of jointly estimating the RFO and SFO by using a continual pilot (CP) defined in an OFDM-based digital video broadcasting (DVB) system. For deriving an unbiased joint RFO and SFO estimator in the current DVB system, a CP subset is selected to simultaneously remove the effect of RFO and SFO. We can observe by simulation that the proposed frequency estimator endowed with a properly selected CP subset is unbiased and performs robustly.

STiMi is a mobile multimedia broadcasting trade standard that was released by the Chinese State Administration of Radio Film and Television in 2006. This paper details the algorithm research and development work on the acquisition for STiMi. First, the STiMi physical layer is briefly reviewed. Secondly, individual algorithms, including time slot detection, fractional frequency offset estimation, integer frequency offset estimation and fine timing synchronization are discussed with simulation results presented. An implemented STiMi receiver prototype is also introduced with a focus on the acquisition algorithms implementation. Finally, the whole acquisition procedure is summarized. Acquisition algorithms and structures presented in this paper are adopted for prototyping and perform well.

This paper presents a blind synchronizer for orthogonal frequency-division multiplexing (OFDM) systems based on signal-to-interference-and-noise ratio (SINR) maximization. Due to the incurred losses from intersymbol interference (ISI) and intercarrier interference (ICI) introduced by synchronization errors, the SINR of the received data drastically drops. By taking advantage of this characteristic, both the symbol time and carrier frequency offsets are intuitively estimated by maximizing the SINR metric. For the SINR metric, two blind SINR estimations are investigated. The estimations do not need prior knowledge of the channel profiles and transmitted data. As such, the proposed maximum SINR (MSINR) synchronization algorithm is nondata aided so that the transmission efficiency can be improved. Moreover, to reduce the computational complexity, the early-late gate technique is proposed for the implementation of the synchronizer. Simulation results exhibit better performance for the MSINR algorithm than conventional techniques in multipath fading channels.