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Ambient backscatter (AB) communication enables the backscatter devices to modulate and transmit data by reflecting surrounding digital video broadcasting (DVB) signals, and has emerged as a promising solution to connect low-power and small-sized devices in Internet of Things (IoT). Unfortunately, the AB receiver may suffer from the strong direct-link interference (DLI) transmitted from the ambient DVB station, making it difficult to decode the backscattered signal (BS) directly. In this paper, to tackle this issue, we propose a DLI cancellation method for AB communications over ambient DVB signals. First, a general signal processing operation for DLI cancellation at the AB receiver is designed, where neither special design on waveform nor cooperation between the ambient DVB station and the backscatter transceiver is required. Then, by minimizing the residual reception power after DLI cancellation, a three-layer parameter searching algorithm is proposed to separate the BS from the ambient DVB signal, which is of low implementation complexity. Simulation results show that when the DLI-to-BS ratio (ISR) is greater than 30 dB, the proposed DLI cancellation method can effectively suppress the DLI at the AB receiver, and the demodulation and capacity performance of the ambient DVB transmission and the backscatter transmission are barely deteriorated, as compared with the scenarios of original DVB transmission without BS and pure backscatter transmission without DLI. In addition, there is a trade-off between the convergence time and the interference cancellation ratio (ICR) performance of the proposed DLI cancellation scheme. [ABSTRACT FROM AUTHOR]

Advanced Television Systems Committee (ATSC) 3.0, a recently developed terrestrial broadcasting standard, supports a Single Frequency Network (SFN), which extends service coverage and enhances received field strength without additional frequency resources. In SFN, multiple transmitters emit identical ATSC 3.0 broadcasting signals, which may cause constructive or destructive interference on a receiver side. The worst situation occurs when two signals from different transmitters are received with the opposite phase and similar power within a sample time, causing the cancellation of the received signal. In order to prevent such signal cancellation, ATSC 3.0 adopted transmitter diversity code filter sets (TDCFS), which is a frequency domain pre-distortion scheme to minimize cross-correlation among multiple transmitter signals in SFN. This paper sets up an ATSC 3.0 SFN consisting of two transmitter sites, transmitting high definition (HD) for mobile service and 4K ultra high definition (UHD) for fixed service. Layered division multiplexing (LDM) and time division multiplexing (TDM) are used to simulcast the two services with different robustness in the same radio frequency (RF) channel. Then, performance is evaluated using a threshold of visibility (ToV) and a successful reception rate. The time and frequency channel responses are changed at the same reception area when TDCFS is applied so the results show that reception performance is improved in the worst situation in SFN. [ABSTRACT FROM AUTHOR]

To meet the ever increasing demand for better service quality and availability, the next generation digital TV (DTV) broadcast, a.k.a., the ATSC 3.0, is developed with new capabilities to deliver 4K ultra-high-definition (4K-UHD) services to fixed receivers, robust HD-quality services to mobile receivers, as well as non-broadcast services (e.g., broadband), including Internet of Things (IoT), Connected Vehicles, etc. To realize these capabilities, it becomes necessary to evolve the existing single-transmitter high-power-high-tower (HPHT) network to multi-transmitter low-power-low-tower single-frequency-networks (SFN), which requires installing new transmitters. Each new transmitter needs a feederlink to receive the service data from the broadcast gateway (BG) for transmission. This feederlink contributes to a significant portion of installation and operational costs of the new transmitters. This paper proposes a wireless in-band distribution link (WIDL) technology, where the distribution data is delivered to the newly deployed transmitters from the existing DTV towers wirelessly sharing the same TV band with the broadcast services. The distribution signal is multiplexed with service signal in the same ATSC 3.0 waveform. Layered division multiplexing (LDM) technology is proposed to achieve more efficient transmission of the distribution signal. The WIDL offers better performance and more robust operation than the on-channel repeater (OCR) technologies. More importantly, it offers the possibility of delivering backhaul data for future applications over the DTV infrastructure, such as IoT and connected vehicles. Therefore, the proposed WIDL is one enabling technology to achieve convergence of broadcast services with broadband and other wireless services on the DTV spectrum. [ABSTRACT FROM AUTHOR]

Single-frequency network (SFN) can be applied to advanced television systems committee (ATSC) 3.0-based terrestrial broadcasting systems to improve the service availability and quality of service without additional spectral resources. The main problem of SFN planning is the co-channel interference caused by multiple transmitters that use the same radio frequency for signal transmission and reception. The effect of the co-channel interference can be minimized by adjusting the network delay and transmit power of multiple transmitters within the SFN coverage area. To adjust the delay and power, it is necessary to estimate the channel impulse response (CIR) from each transmitter to a receiver. To support this process, a transmitter identification (TxID) signal is embedded in an original ATSC 3.0 signal. At the receiver, the individual CIR may be measured by a correlation-process-based TxID detection. However, since the correlation process may require large computational efforts, it is a quite challenging work to design a TxID detection algorithm with reduced complexity. This paper proposes a low-complexity TxID detection algorithm. The design and performance of the proposed algorithm is investigated and analyzed through numerical simulations. The simulation results indicate that the proposed algorithm can offer almost the same performance as the conventional TxID detection algorithm with significantly reduced complexity. [ABSTRACT FROM AUTHOR]

Single frequency networks (SFNs) provides an increased spectral efficiency compared to the traditional multiple frequency networks. However, some coverage areas in SFN can be affected by destructive interferences. In order to reduce these situations, distributed multiple-input single-output (MISO) schemes have been adopted in the new digital terrestrial television standards, Alamouti in DVB-T2 and transmit diversity code filter sets in ATSC 3.0. On the other hand, layered division multiplexing (LDM), a non-orthogonal multiple access technology, has been adopted in ATSC 3.0 due to its spectral efficiency increase compared to time or frequency division multiplexing. The LDM signal is formed by a power superposition of two independent signals, which are designed for different reception conditions (mobile and fixed-rooftop). The combination of distributed MISO and LDM techniques has not been evaluated yet. In this paper, the joint transmission of LDM with distributed MISO is analyzed in terms of complexity and the joint performance is evaluated by means of physical layer simulations. [ABSTRACT FROM AUTHOR]

In this paper, we present laboratory and field test results of layered division multiplexing (LDM) and time division multiplexing (TDM) technologies based on Advanced Television Systems Committee 3.0. The presented field test results include analysis in several scenarios such as rooftop, indoor, and mobile receptions. In order to provide performance comparison of the LDM and TDM technologies, reception power (field strength) and successful reception rate are measured for all the considered scenarios. For in-depth analysis in real field environment, further field measurements such as threshold of visibility, marginal (minimal) reception power, and erroneous second ratio are used for rooftop, indoor, and mobile receptions, respectively. The laboratory and field test results show that the LDM technology not only shows superior performance compared to the TDM technology in all the considered scenarios (rooftop, indoor, and mobile receptions), but also enables broadcaster to efficiently provide a variety of services (e.g., mobile, pedestrian, indoor, and stationary services) with different robustness within a single radio frequency channel. [ABSTRACT FROM AUTHOR]

Two of the main drawbacks of the current broadcasting services are, on the one hand, the lack of flexibility to adapt to the new generation systems requirements, and on the other hand, the incapability of taking a piece of the current mobile services market. In this paper, layered division multiplexing (LDM), which grew out of the concept of Cloud Txn, is presented as a very promising technique for answering those challenges and enhancing the capacity of broadcasting systems. The major contribution of this paper is to present the first comprehensive study of the LDM performance behavior. In particular, in this paper, the theoretical considerations of the LDM implementation are completed with the first computer based simulations and laboratory tests, covering a wide range of stationary channels and the mobile TU-6 channel. The results will support LDM as a strong candidate for multiplexing different services in the next generation broadcasting systems, increasing both flexibility and performance. [ABSTRACT FROM PUBLISHER]

The final coverage and associated performance of a single frequency networks (SFNs) is a joint result of the properties of all transmitters in the SFN. Due to the large number of parameters involved in the process, finding the right configuration is quite complex. The purpose of this paper is to find optimal SFN network configurations for second generation digital terrestrial broadcast system (DVB-T2). Offering more options of system parameters than its predecessor DVB-T, DVB-T2 allows large SFN networks. However, self-interference in SFNs gives rise to restrictions on the maximum intertransmitter distance and the network size. In order to make optimum use of the spectrum, the same frequency can be reused over different geographical areas—beyond the reuse distance to avoid co-channel interference. In this paper, a methodology based on theoretical network models is proposed. A number of network architectures and network reference models are considered here for different reception modes in order to study the effects of key planning factors on the maximum SFN size and minimum reuse distance. The results show that maximum bitrate, network size, and reuse distance are closely related. In addition, it has been found that the guard interval is not the only limiting parameter and that its impact strongly depends on the rest of DVB-T2 mode parameters as well as on the network characteristics (equivalent radiated power, effective height, and intertransmitter distance). Assuming that the carrier to noise ratio requirements are in the vicinity of 20 dB and bitrates over 30 Mb/s, it has been found that the network can be as large as 360 \times 360 km (delivering 39.2 Mb/s) or even 720 \times 720 km (delivering 37.5 Mb/s). The reuse distance will also have a complex dependency on the DVB-T2 mode and especially the network parameters, ranging from below 100 to 300 km. [ABSTRACT FROM PUBLISHER]

In this paper, we present field test results of a layered division multiplexing (LDM) technology for the next generation digital television system, and analyze the results in several scenarios such as rooftop, indoor, and mobile receptions. In order to evaluate performance of the LDM technology, the field strength or the reception power is measured for all considered scenarios. Furthermore, the threshold of visibility, the marginal reception power, and the erroneous second ratio are measured for fixed, indoor, and mobile receptions, respectively. The field test results show that LDM technology enables broadcaster not only to efficiently provide a variety of services (e.g., mobile, indoor, and stationary services) with different robustness within a single radio frequency (RF) channel but also to increase flexible usage of the RF channel. [ABSTRACT FROM AUTHOR]

The evolved multimedia broadcast multicast service ( e MBMS) system was developed to achieve higher spectrum efficiency on video traffic delivery over the long term evolution (LTE) networks. As an integrated component of the LTE, e MBMS can be deployed with great flexibility using the existing LTE infrastructure. However, the current e MBMS was designed as a supplementary subsystem, and has limited capability to deliver high-quality broadcast-type video services in a spectrum efficient manner. This paper first studies the capability and limitations of the current LTE e MBMS system to deliver broadcast services when deployed as single-frequency-network (SFN). Next, potential physical-layer enhancements are investigated for future e MBMS systems to achieve enhanced broadcast service delivery capability, higher spectrum efficiency, improved service quality, and more efficient SFN deployment options. These include wideband transmission, non-orthogonal multiplexing, e.g., layered-division-multiplexing technology, and more flexible orthogonal frequency division multiplexing system configurations, such as longer cyclic prefix and smaller subcarrier spacing. Other technologies defined in the latest next generation digital television system are also discussed that might be applicable to the development of a more capable standalone future e MBMS system. [ABSTRACT FROM AUTHOR]

Time-varying channels destroy the orthogonality among subcarriers in orthogonal frequency division multiplexing (OFDM) systems, and introduce intercarrier interference (ICI). Lots of efforts have been devoted to mitigate ICI in OFDM systems, with different frame structures and channel models, but the computational complexity of the methods is usually very high. In multiple-input multiple-output (MIMO) systems, the complexity is even higher. In this paper, a low-complexity ICI mitigation method is proposed for MIMO-OFDM systems under the assumption of linear time-varying channels. It reduces the complexity of ICI compensation from O(K^3(N^3+MN^2+MN)+NK\log (K)) to O(K(N^3+2MN^2+2MN+2M^2+N\log (K))) , where K is the number of subcarriers, M the number of transmitters, and N the number of receivers. It requires channel estimation based on the linear time-varying channel model, and no transmission overhead is needed. The proposed algorithm applies to all OFDM systems as long as linear time-varying channel estimation is applicable. Time-domain synchronous-OFDM naturally suits for the proposed ICI mitigation algorithm because its receiver is able to easily estimate linear time-varying channels. Simulation with QPSK and 16QAM modulation demonstrates the performance of the proposed method, in comparison with no ICI mitigation case. It shows that 2 dB signal to noise gain is achieved when the uncoded bit error rate is 10^-3 and the normalized Doppler frequency is 0.1. [ABSTRACT FROM AUTHOR]

The second generation digital video broadcasting system for terrestrial broadcasting (DVB-T2) was designed using a toolbox concept. Compared with its predecessor DVB-T, the new standard introduces many new algorithms and allows for a more flexible parameter configuration. The parameters can be perfectly optimized for each reception scenario, ranging from stationary reception with roof-top aerials, up to portable or mobile reception. However, all countries that have already introduced DVB-T2 mainly focus on stationary reception. In contrast, stationary reception is no relevant option for a potential introduction of DVB-T2 in Germany. Instead, a potential roll-out would focus on the benefits of terrestrial broadcasting compared to satellite and cable, i.e., mobility. Within an extensive field trial in northern Germany, the performance of the different parameter configurations and new algorithms offered by DVB-T2 were analyzed in detail, e.g., multiple physical layer pipes, rotated constellations, and multiple-input single-output. This paper presents the trial network and the obtained measurement results, which are based on thousands of individual measurements. Moreover, the document gives recommendations for an optimal parameter configuration. [ABSTRACT FROM AUTHOR]

In this paper, we explain an additional data transmission (ADT) increasing the data capacity of the advanced television systems committee terrestrial digital television (DTV) system, present its field test results conducted in Jeju Island, Korea, and analyze the results in different scenarios. The ADT system can offer an additional data of rate from a few hundred bits per second (bps) to a few megabits per second based on a transmitter identification (TxID) or successive interference cancellation (SIC) techniques. For the field test, the field strength and the required carrier to noise ratio for a stable reception were measured at each test point. Based on the field test, we verify that the TxID- and SIC-based ADT systems can provide an additional data link supporting 160 bps data rate, which is at least 13 dB robust compared to the conventional DTV system, and 2 Mbps data rate which is about 3 dB worse than the conventional DTV system, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a backward compatible multiservice transmission scheme over the digital television terrestrial multimedia broadcasting (DTMB) system is proposed, which is based on embedded constellation and bit division multiplexing. With the proposed scheme, simultaneous transmission of original services and multiple augmented services can be supported in the DTMB system in a backward compatible manner. No additional RF spectrum is required and no additional complexity is introduced to the legacy DTMB receivers. Two schemes over the DTMB system are proposed toward two different requirements, which are maintaining the transmission rate of original services and maintaining the reception SNR-threshold of original services, respectively. Average mutual information analysis and bit error ratio simulations are performed. In both schemes, the increment in the throughput of the DTMB system can be over 7.6 Mb/s in typical mode. [ABSTRACT FROM AUTHOR]

Current digital terrestrial television networks make use of either single frequency networks (SFN) or multifrequency networks (MFN). These network topologies are not ideally suited for delivery of both global and local services in an efficient way. MFNs enable the efficient transmission of local services but need a significant amount of frequency spectrum. The basic principle of SFNs is that all transmitters radiate the same signal synchronized in time and frequency, therefore are especially suitable for global services due to mutual support of the signal by multiple transmitters. Without violating the SFN principle, local services meant to address sub-regions of an SFN must therefore be transmitted throughout the whole network, causing inefficient distribution of local services. This paper describes the complementary techniques adopted by the next generation mobile broadcasting standard digital video broadcasting—next generation handheld for providing global and local contents in SFN topologies: hierarchical modulation (H-LSI) and orthogonal local services insertion (O-LSI) techniques. H-LSI uses hierarchical modulation to transmit local services on top of the global services in areas close to the transmitters, by transmitting the local services in the low priority stream and the global services in the high priority stream. The O-LSI scheme specifies groups of OFDM subcarriers in specific OFDM symbols for the exclusive use of particular transmitters to transmit local services. For both techniques, the transmission of local content through the whole SFN network can be scheduled in a way that different local areas do not interfere with each other. In addition to the description of both H-LSI and O-LSI schemes, the applicability of these approaches in terms of network topologies, implementation issues, and performance evaluation are analyzed. [ABSTRACT FROM PUBLISHER]

Single carrier frequency-domain equalization (SC-FDE) modulations are known to be suitable for broadband wireless communications due to their robustness against severe time-dispersion effects and the relatively low envelope fluctuations of the transmitted signals. In this paper, we consider the use of SC-FDE schemes in broadcasting systems. A single frequency network transmission is assumed, and we study the impact of distinct carrier frequency offset (CFO) between the local oscillator at each transmitter and the local oscillator at the receiver. We propose an efficient method for estimating the channel frequency response and CFO associated to each transmitter and propose receiver structures able to compensate the equivalent channel variations due to different CFO for different transmitters. Our performance results show that we can have excellent performance, even when transmitters have substantially different frequency offsets. [ABSTRACT FROM AUTHOR]

When DVB-T2 uses the option of (distributed) multiple-input single-output transmission mode, a pair of Alamouti-encoded orthogonal frequency division multiplex signals is transmitted simultaneously from two spatially separated transmitters in a single frequency network. Since both transmitters have their own local oscillators, two distinct carrier frequency offsets (CFOs), one for each transmitter-receiver link, occur in the received signal due to the frequency mismatch between the local oscillators. Unfortunately, the multiple CFOs cannot be compensated simultaneously by merely adjusting the carrier frequency at the receiver side, so intercarrier interference (ICI) always exists. In this paper, we present an iterative receiver design to combat multiple CFOs for DVB-T2 application. To estimate both multiple CFOs and channels jointly without sacrificing the spectral efficiency, the joint maximum likelihood (ML) estimation based on the soft information from the channel decoder is used. The proposed receiver performs the iterative joint processing of the data detection, ICI cancelation, and joint ML estimation of the multiple CFOs and channels by exchanging the soft information. We also show that the complexity of the joint ML estimation can be reduced significantly by transforming a huge matrix pseudo-inversion into two sub-matrix pseudo-inversions. The performances are evaluated via a full DVB-T2 simulator. The numerical results show that the mean-squared error performance of the joint ML estimation is closely matched with the Cramér-Rao bound. Furthermore, the resulting bit error rate performance is enhanced in a progressive manner and is able to approach the ideal CFOs-free performance within a few iterations. [ABSTRACT FROM AUTHOR]

Several previous studies have demonstrated that additional low-rate data can be transmitted in Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) systems by modulating the polarity of the transmitter identification (TxID) signal. Previously proposed additional-data transmission schemes can offer an additional reliable transmission channel, and thus they have a very large coverage area compared to that of a DTV signal. Unfortunately, as the cost of a reliable transmission, they have a limitation in their maximum data rate. In this paper, we propose a new additional data transmission scheme based on sequence phase modulation (SPM) to increase the data rate. The proposed scheme exploits not only the polarity but also the phase of a TxID signal, and thus it significantly enhances the data rate compared to conventional schemes. [ABSTRACT FROM PUBLISHER]

In this paper, a single frequency network (SFN) application of the digital terrestrial multimedia broadcasting (DTMB) system in Shanghai is presented. A three-stage implementation practice is described in details. Computer simulations of DTMB receiver in severe dynamic multipath channels are presented to verify the method of SFN adjustments. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel augmented data transmission (ADT) system based on low density parity check (LDPC) code for an additional data stream transmission in the Advanced Television Systems Committee (ATSC) terrestrial digital television system. The LDPC code-based ADT system can provide additional data of rate up to 3 megabits per second (Mbps), which is significantly improved over the conventional data transmission schemes used in the transmitter identification system. Based on the laboratory test, we verify that the LDPC code-based ADT system is only about 1.1 dB away from Shannon limit. [ABSTRACT FROM AUTHOR]

Wireless positioning using digital television (DTV) signals is a promising complementary to global positioning system due to high transmission power and wide coverage of DTV transmitters. Without changing the current infrastructure of Chinese DTV broadcasting network, this paper proposes a positioning scheme using time-domain synchronous (TDS) orthogonal frequency division multiplexing (OFDM) signals in single-frequency networks. The transmission parameter signaling (TPS) embedded in the TDS-OFDM signals is time-division multiplexed as orthogonal frequency-domain pilots, and then the time-domain pseudorandom noise sequence and the frequency-domain TPS are jointly utilized for accurate time of arrival (TOA) estimation for each transmitter. The theoretical bound of the TOA estimation accuracy is also derived. The proposed wireless positioning scheme has no impact on the normal TV program reception. Simulation results show that the positioning accuracy of less than 1 m can be achieved in SFN scenarios. The idea of time-frequency joint positioning can also be applied to other OFDM-based wireless systems. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel Augmented Data Transmission (ADT) system which can transmit an additional data stream in the Advanced Television Systems Committee (ATSC) terrestrial DTV system. The proposed ADT system can offer an additional data of rate up to a few megabits per second (Mbps) based on hierarchical modulation, DTV signal cancellation, and advanced error correction code. The proposed ADT system significantly enhances capability compared with the data transmission schemes used in the transmitter identification (TxID) system. Since the proposed ADT system uses the in-band hierarchical modulation, it does not require any additional RF spectrum to increase the data capacity in a 6 MHz RF channel. Meanwhile, the ADT system has negligible impact to legacy receivers, if the proposed ADT system is deployed over the frequency bands occupied by ATSC A/53 or A/153 services. [ABSTRACT FROM PUBLISHER]

Partial transmit sequence (PTS) is one of the most well-known peak-to-average power ratio (PAPR) reduction techniques proposed for orthogonal frequency-division multiplexing (OFDM) systems. The main drawbacks of the conventional PTS (C-PTS) are high computational complexity and transmission of several side information bits. A new PTS with simple detector is proposed in this paper to deal with these drawbacks of C-PTS. The candidates can be generated through cyclically shifting each sub-block sequence in time domain and combining them in a recursive manner. At the receiver, by utilizing the natural diversity of phase constellation for different candidates, the detector can successfully recover the original signal without side information. Numerical simulation shows that the proposed scheme performs very well in terms of PAPR. The probability of detection failure of the side information demonstrates that the detector could work without any side information with high reliability. The proposed scheme achieves almost the same bit error rate (BER) performance as the C-PTS with perfect side information, under both additive white Gaussian noise (AWGN) channel and Rayleigh fading channel. [ABSTRACT FROM AUTHOR]

In a single frequency network (SFN) for the Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, co-channel interference induced by the multiple transmitters and/or repeaters which use the same output channel is inevitable. Since the presence of interference results in the performance degradation of the SFN, it is crucial to manipulate the interference by adjusting the transmit power and the emission time of each transmitter and repeater within the SFN. In the ATSC terrestrial DTV system, in order to facilitate the interference manipulation process, a transmitter identification (TxID) signal which is embedded in the transmit signal from each transmitter and repeater is recommended. However, such an embedded signal may degrade the DTV signal quality even though the injection level of the TxID signal is very low compared to the DTV signal. Hence, the effect of the TxID signal on the DTV signal needs to be investigated before deploying the SFN with TxID signal. In this paper, the effect of the TxID signal on the performance of legacy DTV receivers is investigated not only with extensive computer simulation but also with laboratory and field tests. According to the various test results, the average performance loss of the conventional DTV receiver due to the TxID signal is less than 0.2 dB when the TxID signal is injected at 30 dB below the DTV signal power. [ABSTRACT FROM AUTHOR]

For broadcast networks, the Single-Frequency Network (SFN) mode is an alternative to the well-known Multi-Frequency Network (MFN) mode, where instead of transmitters operating at different frequencies, all base stations use the same frequency. Besides the optimal frequency reuse, it is usually expected that the more homogeneous distribution of received signal strength reception in an SFN will improve the quality of service. Nevertheless, it should be noted that not all the locations within the service area will benefit from the SFN configuration. Some areas will show a degraded quality caused by the SFN echoes. In this paper, the SFN gain is defined as a parameter describing potential gain or interference. An unambiguous methodology to obtain the actual SFN gain is presented and the variation of the gain is investigated for a DVB-H network as a function of the signal strength difference received from different transmitters. This SFN gain can be used for coverage planning of future broadcast networks. [ABSTRACT FROM AUTHOR]