Terrestrial Digital Multimedia Broadcasting Research Articles

A Segmented Sliding Window Reference Signal Reconstruction Method Based on Fuzzy C-Means

Reference signal reconstruction serves as a crucial technique for suppressing multipath interference and noise in the reference channel of passive radar. Aiming at the challenge of detecting Low-Slow-Small (LSS) targets using Digital Terrestrial Multimedia Broadcasting (DTMB) signals, this article proposes a novel segmented sliding window reference signal reconstruction method based on Fuzzy C-Means (FCM). By partitioning the reference signals based on the structure of DTMB signal frames, this approach compensates for frequency offset and sample rate deviation individually for each segment. Additionally, FCM clustering is utilized for symbol mapping reconstruction. Both simulation and experimental results show that the proposed method significantly suppresses constellation diagram divergence and phase rotation, increases the adaptive cancellation gain and signal-to-noise ratio (SNR), and in the meantime reduces the computation cost.

Robust Pedestrian Dead Reckoning Integrating Magnetic Field Signals and Digital Terrestrial Multimedia Broadcasting Signals

Currently, many positioning technologies complementary to Global Navigation Satellite System (GNSS) are providing ubiquitous positioning services, especially the coupling positioning of Pedestrian Dead Reckoning (PDR) and other signals. Magnetic field signals are stable and ubiquitous, while Digital Terrestrial Multimedia Broadcasting (DTMB) signals have strong penetration and stable transmission over a large range. To improve the positioning performance of PDR, this paper proposes a robust PDR integrating magnetic field signals and DTMB signals. In our study, the Spiking Neural Network (SNN) is first used to learn the magnetic field signals of the environment, and then the learning model is used to detect the magnetic field landmarks. At the same time, the DTMB signals are collected by the self-developed signal receiver, and then the carrier phase ranging of the DTMB signals is realized. Finally, robust pedestrian positioning is achieved by integrating position information from magnetic field landmarks and ranging information from DTMB signals through Extended Kalman Filter (EKF). We have conducted indoor and outdoor field tests to verify the proposed method, and the outdoor field test results showed that the positioning error cumulative distribution of the proposed method reaches 2.84 m at a 68% probability level, while that of the PDR only reaches 8.77 m. The proposed method has been validated to be effective and has good positioning performance, providing an alternative solution for seamless indoor and outdoor positioning.

Fingerprint Fusion Location Method Based on Wireless Signal Distribution Characteristic

In the context of the rapid development of the Internet and the Internet of Things technology, services based on location information have received more and more attention, and people gradually have higher expectations for the quality and experience of positioning services. At present, outdoor positioning technology is becoming mature, but different from empty outdoor areas, there is a highly complex indoor environment with many interference factors, so it is difficult to receive effective satellite signals. To realize the smooth transition of whole-field positioning, it is necessary to study an economical and efficient indoor positioning technology. The existing indoor positioning technologies have some problems, so this paper comprehensively uses the resource-rich Wi-Fi signal, Frequency Modulation (FM) signal and Digital Terrestrial Multimedia Broadcast (DTMB) signal as the positioning data sources, and proposes a fingerprint fusion positioning method based on the wireless signal distribution characteristic. Experiments show that the proposed method improves localization accuracy by 30% compared to localization with Wi-Fi alone.

An Enhanced Pedestrian Dead Reckoning Aided With DTMB Signals

Pedestrian Dead Reckoning (PDR) is a good alternative positioning method in Global Navigation Satellite Systems (GNSS)-challenged environments. It has the advantage in terms of infrastructure-independent, while the disadvantage is that, the estimated errors grow rapidly with time. The Digital Terrestrial Multimedia Broadcasting (DTMB) signals have strong transmission power, which contributes to better urban propagation and building penetration than GNSS signals. So, in this paper, an enhanced PDR algorithm aided with DTMB signals is proposed. In the study, a complete software-defined radio receiver is developed to estimate the Doppler speed and range information from DTMB signals. To reduce the accumulated errors of the PDR, the Extended Kalman Filter (EKF) algorithm is carried out to fuse the information of Doppler speed and ranging from the DTMB signals, as well as the information of walking speed and heading from the PDR. The results of the field tests showed that the 95% positioning error of the proposed algorithm is less than 3.94 m, while the PDR only is less than 9.19 m, which suggests the effectiveness of the proposed method to provide continuous positioning by fusing DTMB signals with PDR.

A Joint Low-Rank and Sparse Method for Reference Signal Purification in DTMB-Based Passive Bistatic Radar.

In a digital terrestrial multimedia broadcasting (DTMB)-based passive bistatic radar (PBR) system, the received reference signal often suffers from serious multipath effect, which decreases the detection ability of low-observable targets in urban environments. In order to improve the target detection performance, a novel reference signal purification method based on the low-rank and sparse feature is proposed in this paper. Specifically, this method firstly performs synchronization operations to the received reference signal and thus obtains the corresponding pseudo-noise (PN) sequences. Then, by innovatively exploiting the inherent low-rank structure of DTMB signals, the noise component in PN sequences is reduced. After that, a temporal correlation (TC)-based adaptive orthogonal matching pursuit (OMP) method, i.e., TC-AOMP, is performed to acquire the reliable channel estimation, whereby the previous noise-reduced PN sequences and a new halting criterion are utilized to improve channel estimation accuracy. Finally, the purification reference signal is obtained via equalization operation. The advantage of the proposed method is that it can obtain superior channel estimation performance and is more efficient compared to existing methods. Numerical and experimental results collected from the DTMB-based PBR system are presented to demonstrate the effectiveness of the proposed method.

Using DTMB-Based Passive Radar for Small Unmanned Aerial Vehicle Detection

There is inevitable polarization angle deviation between the target echo signal and the direct path signal of illuminator of opportunity (IO) in passive radar. In order to investigate the potential performance loss in target detection induced by the random deviation, small unmanned aerial vehicle (UAV) detection experiments with digital television terrestrial multimedia broadcasting- (DTMB-) based passive radar are conducted in this paper. Experimental results show that the polarization angles of the clutter signal and target echo signal are inconsistent. When the polarization diversity technology is used to suppress the clutter signal, the processing performance of the target echo signal may be reduced. On the premise that clutter is effectively suppressed by the processing algorithm, polarization synthesis can maximize the target echo signal processing gain. The effectiveness of the target localization algorithm combining time difference of arrival (TDOA) and direction of arrival (DOA) is also verified with polarization diversity reception in this paper.

Reference Signal Reconstruction Under Oversampling for DTMB-Based Passive Radar

The robust reconstruction of the reference signal is one of the key technologies in passive radars. This paper investigates the reference signal reconstruction problem for digital television terrestrial multimedia broadcasting (DTMB)-based passive radar. The conventional digital signal processing for the DTMB signal is usually based on the assumption of the equal bandwidth sampling (EBS) in which the sampling rate is equal to the nominal bandwidth 7.56 MHz defined in the DTMB standard. But we reveal that the high-frequency subcarriers of the DTMB signal are aliased under the EBS, which will degrade the reconstruction performance. Thus we suggest the oversampling approach for the DTMB-based passive radar. The least squares (LS) channel estimation under oversampling is thoroughly analyzed. Moreover to solve the problem that the LS algorithm cannot estimate the time-domain response of the channel under oversampling, we propose two modified LS channel estimation algorithms, namely the Tikhonov regularization LS and reduced rank approximation LS. The advantages of the reference signal reconstruction under oversampling over that under EBS are validated by both the simulation and field experimental data.

Cochannel Interference in DTMB-Based Passive Radar

This paper discusses the situation with cochannel interferences in the digital television terrestrial multimedia broadcasting (DTMB)-based passive radars. The cochannel interference comes from the station that works in the same frequency with the adopted illuminator of opportunity (IO), but broadcasts different contents. Based on the frame structure of the DTMB signal, the features of the cochannel interference are elaborated. Analyses show that several interfering peaks present in the range-Doppler map when the cochannel interference has the same frame header with the IO. These interfering peaks can be used to identify the existence of cochannel interferences. In addition, to eliminate the influences of the cochannel interference on the target detection, we propose a method that can effectively remove the interfering peaks. The simulation and field experimental results verify the effectiveness of the proposed method.

PN Signal as a New Illuminator of Opportunity for Passive Radar Applications

In this letter, we use the known pseudorandom noise (PN) signal in the digital television terrestrial multimedia broadcasting (DTMB) system as a new illuminator of opportunity for the passive radar. We propose a computationally efficient signal processing method for the PN-based passive radar (PNPR). The proposed method takes advantage of the distinctive structure of the PN signal and constructs a locally remapped PN signal. The circular cross-correlation between the remapped PN signal and the original PN signal is an ideal impulse function. Thus, the PNPR even does not need to do the clutter cancellation. The proposed method is validated via both the simulated and experimental data.

An Environmentally-Adaptive Positioning Method Based on Integration of GPS/DTMB/FM.

The Global Positioning System (GPS) yields good precision and availability in open outdoor environment. However, the errors of GPS may suffer degradation in some complex environments, such as forests and urban canyons. To solve this problem, a new positioning method is designed integrating GPS, Digital Terrestrial Multimedia Broadcast (DTMB) and frequency-modulated (FM) radio signal. In this method, the DTMB transmitter acts as a pseudo-satellite to assist GPS positioning. Furthermore, the FM fingerprint positioning is used to correct the positioning bias. An adaptive selection scheme is proposed to provide an optimal integration mode of the sensors. Field experiments in complex environment were carried out for evaluation. Comparing to the GPS-only and GPS + DTMB approach, positioning accuracy was improved by at least and with the proposed method, respectively.

Channel-Allocation Plan for National and Local T-DAB Services in VHF Band III

The digital audio broadcasting (DAB) system is mainly designed for large-area coverage and is suited for a single-frequency network (SFN) operating in Very High Frequency (VHF) Band III. To operate successfully, the SFN requires a different network-planning approach for multiple-frequency networks and should avoid self-interference. This paper focuses on nationwide SFN planning and DAB channel-allocation planning to replace all frequency-modulation (FM) services with terrestrial DAB services in VHF Band III. In South Korea, VHF Band III has been used for terrestrial digital multimedia broadcasting (T-DMB) services; thus, available frequencies should be investigated for T-DAB services and the nationwide SFN. An approach for broadcasting channel-interference analysis is proposed herein. For the interference analysis, the geographical features and the information for stations of legacy FM radio broadcasting and T-DMB, such as transmission parameters, are considered. The ratio of the interference area to the coverage is calculated via the channel-interference analysis. Areas affected by the self-interference in the nationwide SFN are investigated. The results of this paper provide insights regarding channel-allocation planning for T-DAB services and an approach for nationwide SFN planning.

Bidirectional Broadcasting in Next Generation Broadcasting-Wireless (NGB-W) Network

With the increasing video on demand service need in broadcasting television and the development of triple play strategy, the next generation wireless network television system has been presented. With the advantages of interactive capability, next generation broadcasting-wireless (NGB-W) experiment network can cooperate with digital terrestrial multimedia broadcasting and China mobile multimedia broadcasting downlink systems. In this paper, the key technologies of NGB-W are described in detail. Application test and network deployment of NGB-W in Shanghai are presented to validate its extensive use.

The Design and Performance Analysis of DTMB System

Various standard in digital television broadcasting system has been developed in the world, one of which is the Digital Terrestrial Multimedia Broadcasting, or abbreviated as DTMB that currently used by China and Hong Kong. DTMB has several standard configurations and parameters. In this research, DTMB system was designed and the results was validated through simulation using computer program, named Simulink. The parameters used in this research is the FEC with code rate of 0.4, 4QAM modulation, interleaver mode 1 and using a single carrier transmission mode. Stream format used in the simulation was MPEG2-TS as the input for DTMB system. Parameters selection was based on low implementation complexity, but with good results. Two important things in DTMB system is the existence of FEC and TDS-OFDM. FEC consists of cascaded BCH as the outer encoder/decoder (codec) and LDPC as the inner codec. The reason of using TDS-OFDM because it provides better picture quality when the receiver is in motion. The test results have shown that for static video, DTMB was able to receive video with identical quality compared to the original video, when the value of SNR=11dB and SNR=12dB for dynamic video. It is shown that after going through the process from LDPC to BCH, the number of bit errors decreased while the value of SNR increased.

제한수신 기능 기반 T-DMB 시스템

ABSTRACT Current terrestrial Digital Multimedia Broadcasting (T-DMB) is conducting .the emergency alert broadcast, or can view a variety of broadcasting. However, propagation shadow area is a situation where the service is limited due to limitations of facilities investment. In addition, there is the problem of T-DMB broadcasting is for viewing only a restricted area and a mobile device because the mobile is also T-DMB viewing device impossible. In this paper, it receives a T-DMB broadcasting as a way to solve the problems of the T-DMB system, which was studied the re transmission to the mobile device. Accordingly, by receiving the broadcast may be watched in the mobile device the T-DMB reception impossible. Also provides a one-way/two-way authentication mechanism using a conditional access function, and the system was configured so that the user can watch only the registered broadcasting. 키워드 : 멀티미디어 방송, 제한수신, 지상파 방송, T-DMB Key word : Multimedia Broadcasting, Reception Function, Terrestial Broadcasting, T-DMB

A consumer synchronizer for T-DMB receiver based on cooperative communications in emergency alert systems

Currently, terrestrial digital multimedia broadcasting (T-DMB) systems offer an emergency alert service called automatic emergency alert service (AEAS) in emergency alert systems. The performance of T-DMB receiver for AEAS can be enhanced using cooperative communication techniques. This paper assumes the T-DMB receiver based on a cooperative communication model. Since synchronization is crucial in the performance of cooperative communications, a novel consumer synchronizer is proposed in this paper for the T-DMB receiver based on cooperative communications. The presented synchronizer includes the identification of the selected relays, which is especially required in the best-relay selection for cooperative communications. Furthermore, a channel estimation approach is suggested in the synchronizer, which is suitable for T-DMB receivers under high frequencyselectivity. The experimental results reveal that the proposed synchronizer further enhances the performance of T-DMB receiver based on cooperative communications in emergency alert systems.

Implementation of Compact Polyphase Channel-Select Filters for Multistandard Broadcasting

An 8th-order fully electronically programmable complex filter based on current amplifiers for multistandard mobile TV applications is presented. Its center frequency, pole frequency, and gain are electronically programmable to accommodate both Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) and Terrestrial Digital Multimedia Broadcasting (T-DMB). The proposed solution avoids employing capacitor and resistor arrays leading to a compact design (0.51 $\mathrm{mm}^{2}$ ). It adopts minimum number of amplifiers for maintaining relatively low power consumption (2.55 mW). The experimental results obtained from a 0.18- $\mu $ m digital CMOS process show that the proposed design achieves spurious-free dynamic range (SFDR) of better than 65 dB and image rejection ratios of more than 38 dB.

Narrowband Interference Cancelation Based on Priori Aided Compressive Sensing for DTMB Systems

In this paper, a novel narrowband interference (NBI) cancelation scheme based on priori aided compressive sensing (CS) for digital terrestrial multimedia broadcasting systems is proposed. The repeated training sequences in the transmitted symbols are exploited by differential measuring to acquire the CS measuring vector of the NBI, and for joint acquisition of the NBI support priori. Using the proposed priori aided sparsity adaptive matching pursuit algorithm, the sparse high-dimensional NBI can be accurately reconstructed from the measuring vector of much smaller size obtained through the proposed CS-based differential measuring method. It is verified by theoretical analysis and simulations that the proposed method outperforms conventional anti-NBI methods under multipath broadcasting channels.

A signaling emergency alert system multiplexed with T-DMB channel for emergency alert service

Mobile broadcasting services are considered effective methods for emergency alert delivery. Terrestrial digital multimedia broadcasting (T-DMB) offers an emergency alert service called automatic emergency alert service (AEAS). However, the conventional AEAS is inefficient in the aspects of alert service channel, disabled T-DMB receiver, and location-based service. Therefore, this paper proposes a novel signaling method in order to overcome the drawbacks of the AEAS. The presented alert system exploits an additional alert channel, which is multiplexed with the conventional T-DMB channel. This paper also addresses the multiplexing approach, which effectively eliminates the interference between the additional alert channel and the TDMB channel. The simulation results confirm that the proposed signaling method effectively offers the emergency alert services in T-DMB1.

Design and implementation of a novel emergency wake-up alert system within a conventional T-DMB service network

Existing emergency alert techniques of terrestrial-digital multimedia broadcasting (T-DMB) and digital audio broadcasting (DAB) can be executed only when the receivers are activated. To overcome the limitation of existing technique, a novel emergency wake-up alert system within a conventional T-DMB service network is proposed. The emergency wake-up alert signal is periodically generated by emergency transmission data unit (ETDU) and then transmitted through the conventional T-DMB/DAB station. After receiving the emergency wake-up alert signal, T-DMB/DAB receiver can be wake-up, activating and result in showing emergency broadcasting contents to people. To obtain frequency efficiency, the emergency wake-up alert signal is overlaid onto the conventional T-DMB frequency band using a direct sequence spread spectrum technique. To assess the performance of the developed ETDU, simple RF transmitter, test receiver and measurement equipment are used. The performance is checked with different values of emergency wake-up alert signal to T-DMB power ratio. The laboratory test results shows that the wake-up alert signal can be transmitted without degrading the existing T-DMB signal quality and can be detected at very low power emergency wakeup alert signal, e.g., as low emergency wake-up alert signal to T-DMB power ratio as -22.2dB.

모바일 기기에서 보간된 영상에 대한 블로킹 잡음 저감

Display resolution of mobile devices such as smart phones is rapidly increasing. Displays of newly released mobile devices have more than two million pixels. However, most of multimedia contents to be displayed on mobile devices have much smaller pixels. For example, a T-DMB(Terrestrial Digital Multimedia Broadcasting) sequence consists of 320x240 pixels. Most of sequences of internet streaming video are made of less than 720x480 pixels. In order to display low resolution sequence on high resolution displays, image interpolation should be employed. However, enlargement of size would result in reduction of perceived image quality. Especially, increased visibility of blocking noises due to image enlargement is one of the major factors affecting perceived image quality. This paper proposes a blocking noise reduction method for interpolated image sequences. Proposed method can reduce blocking noises effectively while preserving edges. Also proposed method utilizes addition, subtraction, bit shift and comparison operations so that it can be easily implementation for mobile devices.