Digital Terrestrial Television Broadcasting Research Articles

Performances of Orthogonal Wavelet Division Multiplex (OWDM) System Under AWGN, Rayleigh and Ricean Channel Conditions

Orthogonal Wavelet Division Multiplexing (OWDM) has been considered as an alternative of Orthogonal Frequency Division Multiplexing (OFDM) in the recent years. OWDM has lower computational complexity and higher flexibility compared to its OFDM counterpart. The core component of OWDM is wavelet. Wavelet has been a much investigated and applied topic in digital image processing for a long time. Recently, it has drawn considerable attention of the researchers working in communication field. In this work we investigate the performances of OWDM under different channel conditions. We consider three channel conditions namely Additive White Gaussian Noise (AWGN), Rayleigh, Ricean, and frequency selective. We consider a number of wavelets namely Haar, Daubechies, Biorthogonal, Reverse Biorthogonal, Coiflets, and Symlets in OWDM design. For system model we choose Digital Video Broadcasting-Terrestrial (DVB-T). Originally DVB-T system was designed based on OFDM. In this work we use OWDM instead. The simulation results show OWDM outperforms OFDM in terms of bit error rate (BER), noise resiliency, and peak-to-average ration. The results also show that the Haar wavelet based OWDM outperforms other wavelets based OWDM system under all three considered three channel conditions.

A 280 W LDMOS broadband Doherty PA with 52% of fractional bandwidth based on a multi-line impedance inverter for DVB-T applications

We introduce a new technique for the design of an output combiner for Doherty power amplifier (DPA) and its effective exploitation for the development of a wideband laterally diffused metal oxide semiconductor (LDMOS) DPA. The design is enabled by a two-line impedance inverter for the DPA back-off operation, which is capable of 52% of fractional bandwidth. The technique is validated by the development of a DPA prototype for Ultra high frequency terrestrial digital video broadcast (DVB-T) applications, with optimized peak power and efficiency over 470–806 MHz. The prototype delivers between 40 and 53% of average efficiency across the band, at 49 dBm output power in average across the bandwidth, and supporting DVB-T signals with 8 MHz bandwidth and a peak-to-average power ratio of 10.5 dB. It achieves the target adjacent channel power ratio of −52 dBc at 750 MHz if digital pre-distortion is applied, and provides 47.8 dBm of output power with a drain efficiency of 44.3%.

Adaptive fuzzy assisted detector under impulsive noise for DVB-T systems

The main novel contribution of this paper is the improvement achieved on the Digital Video Broadcasting-Terrestrial (DVB-T) system by the addition of a fuzzy median filter to reduce the effect of impulsive components. The proposed detector includes the fuzzy median filter and can be adaptively adjusted according to the noise level and type of the noise. The system is studied under Gaussian and impulsive noise. Simulation results show that fuzzy assisted detector reduces the effect of impulsive noise and improves the performance of the system significantly while also working efficiently in Gaussian noise.

EMC performance measurements for professional wireless microphone systems

With shrinking spectral bandwidths and more intense use of the remaining frequency areas, the importance of good electromagnetic compatibility (EMC) performance of professional wireless microphone systems, as used by broadcasters, is increasing. A wireless microphone system consists of one or more pocket or handheld transmitters and usually the same amount of receivers. Both have to be immune against disturbances, and on the other hand they should not produce interferences. This paper deals with electromagnetic compatibility (EMC) performance tests of three analogue professional wireless microphone systems. The authors describe the complete measurement procedure using two different setups. These setups employ the pocket transmitter or the receiver as device under test (DUT). Different disturbance signals are used utilizing amplitude modulation (AM), frequency modulation (FM) or digital video broadcast-terrestrial (DVB-T). The audio quality of the transmission system is rated with the total harmonic distortion plus noise (THD+N). Additionally, the authors investigate intermodulations (third harmonic) caused by the transmitter. The results of all performance tests are extensively discussed.

Coexistence Between DVB-T/T2 and LTE Standards in Common Frequency Bands

In the last decade, fulfilling the growing users' expectations on the quality of provided multimedia services is one of the biggest challenges for different wireless communication systems. However, many times, different kinds of wireless systems can operate in the same (shared) frequency band. Such coexistence generally negatively affects the performance of the systems colliding. This is especially true for the widely used Digital Video Broadcasting-Terrestrial (DVB-T) or upcoming DVB-2nd Generation Terrestrial (DVB-T2) and Long-Term Evolution (LTE) standards, operating in Europe. Hence, the aim of this paper is to explore the impact of interfering mobile telecommunication services on the mobile TV services provided by LTE and DVB-T/T2 systems in the same frequency band. For the simulation of the coexistence between the LTE and DVB-T/T2 services on the physical layer level, an appropriate method is proposed and complex simulation tools are coupled. The results, presented as a dependence of modulation error ratio at the receiver input and bit error ratio at the channel decoder input on the spectral level ratio, show comparable performances for DVB-T and DVB-T2 systems. Results from simulations are verified by laboratory measurements and should help to better understand the influence of co-channel interferences from LTE mobile networks on DVB-T/T2 networks for mobile transmission scenarios.

Comparative Analysis of DVB System for Different Encoding Techniques with Compressed Images

Objectives: In this paper encoding techniques used in the Digital Video Broadcasting-Terrestrial (DVB-T) system have been discussed. The paper focuses upon the comparison between the different types of encodings as a part of the DVB-T standard. Methods/Analysis: Different types of encoding methods which could be the part of the DVB-T standard have been considered .The system used is able to measure and analyze the performance by using different encoding techniques along with the Orthogonal Frequency-Division Multiplexing (OFDM). Findings: DVB-T was developed by the Digital Video Broadcasting (DVB) Project that was basically for broadcasting. The compressed images, digital audio, compressed videos and other forms of data in Moving Picture Expert Group (MPEG) transport stream, through OFDM modulation is transmitted by this DVB-T system. Novelty /Improvement: In the DVB-T Reed Solomon encoding is used to encrypt the data. Hybrid coding has been proposed as the way to improve the performance.

Analysis on Interference Impact of Wi-Fi on Digital Terrestrial Television Broadcasting

Transition from Analogue Terrestrial Television Broadcasting to Digital Terrestrial Television Broadcasting (DTTB) in the 470-862 MHz band made available amount of spectrum so-called digital dividend for other services i.e. 790-862 MHz band (800 MHz) to mobile service. Recently the 694-790 MHz band (700 MHz) was also allocated to mobile service in ITU Region 1. Spectrum allocated to a broadcasting service but not used locally is called as TV white spaces (TVWS). It is possible to introduce TVWS services in 470-790 MHz band under the condition that other services in this band already operating, or planned in the country and in neighboring countries, are adequately protected and this use does not violate the current ITU Radio Regulations. TVWS under some conditions locally could be used for mobile communication systems e.g. unlicensed Wireless Fidelity (Wi-Fi) using cognitive radio. As TVWS are located in the UHF band, the use of TVWS can provide significantly better coverage and wall penetration inside buildings than 2.4 GHz and 5 GHz range Wi-Fi frequencies. The exact amount of available spectrum for TVWS at any location will be dependent upon each country national situation e.g. DTTB planning configuration, other services use in the band. In case of deploying Wi-Fi in the TVWS the interference impact of Wi-Fi on DTTB has to be taken into account. The aim of this paper is to analyze the interference impact of Wi-Fi on DTTB. In this paper the interference occurring probability in DTTB receiver was evaluated by using Spectrum Engineering Advanced Monte-Carlo Analysis Tool (SEAMCAT).

Experimental Research of Dual-Polarization Passive Radar Based on DTTB Signal

The passive radar is a hot research topic. A multi-channel wideband passive radar experimental system is designed and the digital television terrestrial broadcasting (DTTB) signal is chosen to carry out the target detection experiment of civil aviation aircraft. The polarization and spatial filtering methods are used to solve the strong direct path interference suppression problems brought by the receiving system location; combined with the characteristics of DTTB signal, the block length selection interval in the block batch processing method for range-Doppler images calculation is given; the clutter suppression performance is compared through the experimental data receiving from different bistatic polarization channels, the conclusion is different from the monostatic radar and it can guide the passive radar experiment.

Feasibility Study on Aircraft Positioning by Using ISDB-T Signal Delay

This letter is concerned with experimental results of aircraft positioning by using terrestrial digital broadcasting signal delay. Passive bistatic radar (PBR) is expected to be a conventional primary surveillance radar alternative, and it can also achieve expanding coverage area of the conventional radar. The PBR sensors allow the detection and tracking of noncooperative targets illuminated by transmitters of opportunity such as communication systems [digital terrestrial television broadcasting (DTTB), AM/FM, 3G/LTE base stations, etc.] or conventional radar system. Especially, the DTTB signals are the most expected radio waves. In this letter, we show experimental results of aircraft positioning by using the signal delay profile of DTTB whose type is Integrated Services Digital Broadcasting–Terrestrial (ISDB-T) used in Japan. It will be shown that the ISDB-T signal delays are useful surveillance systems.

地上波によるHD+SDマルチチャネル放送

地上波によるHD+SDマルチチャネル放送

A Survey of the DVB-T Spectrum: Opportunities for Cognitive Mobile Users

Cognitive radio (CR) systems are designed to utilize the available radio spectrum in an efficient and intelligent manner. Terrestrial Digital Video Broadcasting (DVB-T) frequency bands are one of the future candidates for cognitive radio applications especially because after digital television transition the TV white spaces (TVWS) became available for radio communication. This paper deals with the survey of the DVB-T spectrum; wideband measurements were performed on mobile platform in order to study the variation of the radio signal power in city area aboard a moving vehicle. The measurement environment was a densely built-in region where the proper DVB-T receiving was guaranteed by three TV transmitters, utilizing three central channel frequencies using 610, 746, and 770 MHz. In our paper the methods, the applied antenna, and measurement devices will be presented together with simulated and measured fading statistics. The final result is an estimation of the cognitive DVB-T spectrum utilization opportunity; furthermore a scenario is also proposed for secondary channel usage.

Influence of the LTE System using Cognitive Radio Technology on the DVB-T2 System using Diversity Technique

In recent years, the development of advanced wireless communication systems has been rapidly progressing. In Europe, the 2nd Generation Terrestrial Digital Video Broadcasting (DVB-T2) and Long-Term Evolution (LTE) are the most promising techniques to provide multimedia services efficiently (in flexible quality and with high spectrum efficiency). The purpose of this work is to explore possible influences of the LTE uplink services, using cognitive radio (CR) technology, on the area which is covered by DVB-T2 services. In the case of DVB-T2, both single-input single-output (SISO) and multiple-input single-output (MISO) transmission techniques are considered. The defined coexistence scenarios are measured with an appropriate measurement testbed. The performance of the received TV signal is evaluated on its physical layer (PHY) level. The obtained results allow better understand the influence of LTE system on DVB-T2 which is using diversity technique in the same RF channel (co-channel coexistence). One of the main results is that there are the same requirements on the Forward Error Correction (FEC) decoding process in the DVB-T2 receiver, when power imbalances between TV transmitters (an both SISO and MISO modes) are considered at the interfering LTE signal. This finding was also proved by analysis of variance (ANOVA).

Micro‐Doppler signatures of helicopters in multistatic passive radars

This study presents an analysis of micro-Doppler signatures of helicopters obtained using a network of passive radar receivers utilising multistatic geometry. In the multistatic scenario, for each passive radar receiver the target is visible from different bistatic angles, which results in different micro-Doppler signatures. This feature allows additional information on the observed helicopter target to be obtained. The presented concept has been successfully verified by the authors using the real micro-Doppler signatures of a helicopter collected during the measurement campaign. As an illuminator of opportunity for the passive radar network a commercial digital video broadcasting-terrestrial (DVB-T) transmitter was used. The results of the applied micro-Doppler analysis for the real multistatic passive radar measurement carried out are presented in this study. In addition, some examples of inverse synthetic aperture radar (ISAR) images of helicopter rotor blades based on micro-Doppler analysis in the multistatic configuration are shown in this study.

Reduced complexity generalised likelihood ratio detector for digital video broadcasting terrestrial‐based passive radar

The high resolution of the digital video broadcasting terrestrial (DVB-T) signals leads to a dramatically large number of observation samples in an integration time of a DVB-T-based passive radar. Hence, because of the high computational complexity (CC), applying extensive cancellation algorithm and generalised likelihood ratio (GLR) detector seems to be impractical in the DVB-T-based passive radars. In this study, the authors derive a reduced complexity GLR detector for the DVB-T-based passive radar in the presence of the clutter, the interfering targets and the noise. The proposed detector employs the split received signal to reduce the CC substantially compared with the methods that process the whole signal at once. Moreover, the CC reduction in the proposed method does not lead to a degradation in Doppler resolution and the detection performance. Simulation results are also corroborated with the theoretical analysis.

A Grating Monopole Antenna on Metamaterial Using MSRR for DVB-T Application

This work presents a novel broadband monopole antenna for digital video broadcasting-terrestrial (DVB-T) application. The proposed antenna consists of a grating patch and a concave rectangular ground plane with defected ground plane, and the Multiple Split-Ring Resonator (MSRR). The added part in the ground plane and the meta-material are used to enable the antenna height reduction for fixed ranges of operating frequency. The antenna can operate from 468 MHz to 894 MHz frequency range corresponding to 62.5% of impedance bandwidth for |S11|<-7.5 dB. Details of the proposed antenna designs and experimental results of the constructed prototypes are presented and discussed.

A review of Lesotho’s digital migration challenges: Policy lessons from global and regional experiences

Abstract This article presents an analysis of Lesotho’s apparent challenges in its quest to migrate from analogue to digital terrestrial television broadcasting (DTTB) from 2006 to 2015. The move towards DTTB had given the state-owned Lesotho National Broadcasting Services a glimmer of hope to strengthen its position in the local market and thwart competition from South African broadcasters. However, the country lacked a policy direction or a clear road map to gain resources for DTTB development and subsequently failed to meet the international analogue switchoff deadline of 17 June 2015. Given the high level of foreign television service penetration in Lesotho, I argue that the government’s weak and sluggish intervention spells tragedy for the national broadcaster in the digital era, unless corrective policy measures based on comparative lessons from early adopters, with a rapid and coordinated implementation strategy as proposed in this article, are vigorously pursued.

A Near-Capacity MIMO Coded Modulation Scheme for Digital Terrestrial Television Broadcasting

Multiple-input multiple-output (MIMO), which can provide ultrahigh data transmission rate, is one of the key technologies for the next generation digital terrestrial television broadcasting (DTTB) standards. This paper proposes a near-capacity MIMO bit-interleaved coded modulation scheme with either independent or iterative demapping (BICM/BICM-ID) for the DTTB system. First, the amplitude phase shift keying (APSK) constellation with Gray mapping is proposed to replace the conventional Gray quadrature amplitude modulation (QAM) counterpart. From the perspective of average mutual information analysis, Gray-APSK has certain shaping gain compared to Gray-QAM for both independent and iterative demapping schemes. Besides the APSK constellation, a novel bit interleaver named bit mapping, which takes into account the unequal error protection of both APSK constellations and low-density parity-check codes, is proposed to further improve the system performance. The tool of extrinsic information transfer chart is utilized to analyze and design the optimal bit mapping for the BICM/BICM-ID scheme. Bit error rate simulations are finally carried out to verify the superiority of the proposed MIMO coded modulation scheme.

The effects of non-linearity in spectrum sensing receivers

This paper analyses the effects of receiver non-linearity on the performance of the most commonly utilized signal detectors in cognitive radio systems. The analysis covers both self-modulation products of a single orthogonal frequency-division multiplexing (OFDM) signal and intermodulation(IM)products of two OFDM signals, and also their contribution to the probability of false detections. As a result, this work presents the linearity requirements for the spectrum sensor receiver front-end as a function of the sensitivity of the signal detector. Furthermore, we show that the cyclostationary feature detectors are more robust than the energy detectors against IM products of multiple interferers. Theoretical results are verified in measurements with a cyclostationary feature detector using digital video broadcasting – terrestrial (DVB-T) signals as an example.

Compressive sensing–based algorithm for passive bistatic ISAR with DVB-T signals

Inverse synthetic aperture radar (ISAR) images can be obtained using digital video broadcasting–terrestrial (DVB-T)–based passive radars. However, television broadcast–transmitted signals offer poor range resolution for imaging purposes, because they have a narrower bandwidth with respect to those transmitted by a dedicated ISAR system. To reach finer range resolutions, signals composed of multiple DVB-T channels are required. Problems arise, however, because DVB-T channels are typically widely separated in the frequency domain. The gaps between channels produce high grating lobes in the image domain when Fourier-based algorithms are used to form the ISAR image. In this paper, compressive sensing theory is investigated to address this problem because of its ability to reconstruct sparse signals by using incomplete measures. By solving an optimization problem under the constraint of signal sparsity, passive ISAR images can be obtained with strongly reduced grating lobes. Both simulation and experimental results are shown to demonstrate the validity of the proposed approach.

Experimental evaluation of theperformance of 2×2 MIMO-OFDM for vehicle-to-infrastructure communications

In this paper, a novel 2×2 multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) testbed based on an Analog Devices AD9361 highly integrated radio frequency (RF) agile transceiver was specifically implemented for the purpose of estimating and analyzing MIMO-OFDM channel capacity in vehicle-to-infrastructure (V2I) environments using the 920 MHz industrial, scientific, and medical (ISM) band. We implemented two-dimensional discrete cosine transform-based filtering to reduce the channel estimation errors and show its effectiveness on our measurement results. We have also analyzed the effects of channel estimation error on the MIMO channel capacity by simulation. Three different scenarios of subcarrier spacing were investigated which correspond to IEEE 802.11p, Long-Term Evolution (LTE), and Digital Video Broadcasting Terrestrial (DVB-T)(2k) standards. An extensive MIMO-OFDM V2I channel measurement campaign was performed in a suburban environment. Analysis of the measured MIMO channel capacity results as a function of the transmitter-to-receiver (TX-RX) separation distance up to 250 m shows that the variance of the MIMO channel capacity is larger for the near-range line-of-sight (LOS) scenarios than for the long-range non-LOS cases, using a fixed receiver signal-to-noise ratio (SNR) criterion. We observed that the largest capacity values were achieved at LOS propagation despite the common assumption of a degenerated MIMO channel in LOS. We consider that this is due to the large angular spacing between MIMO subchannels which occurs when the receiver vehicle rooftop antennas pass by the fixed transmitter antennas at close range, causing MIMO subchannels to be orthogonal. In addition, analysis on the effects of different subcarrier spacings on MIMO-OFDM channel capacity showed negligible differences in mean channel capacity for the subcarrier spacing range investigated. Measured channels described in this paper are available on request.