Radial Basis Functions Neural Network (RBFNN) as the outcome of recent research provides a simple model for complex networks. This is achieved by employing the Radial Basis Function (RBF) in the network as hidden neuron patterns. The optimal properties of the RBFs pave the way for stable approximation. However, it is generally rather difficult to determine the locations of the centers and the shape parameter. In this article, we will present an evolutionary approach for learning parameters. The approach is based on genetic algorithms. It consists of three well-defined feed-forwarding Phases, and uses a very efficient fitness evaluation method, the so-called Power function.

Multiple-input multiple-output (MIMO) is one of the key technologies for the next generation digital terrestrial television broadcasting (DTTB). This paper proposes a near-capacity MIMO bit-interleaved coded modulation (BICM) scheme for DTTB systems. The amplitude phase shift keying (APSK) constellation with Gray mapping is applied to the BICM scheme. From the perspective of average mutual information, APSK has the advantage of shaping gain compared to its quadrature amplitude modulation (QAM) counterpart. Moreover, a new kind of bit interleaver named bit mapping, which takes into account the unequal error protection of both APSK and low-density parity-check (LDPC) codes, is proposed to further improve the system performance. The tool of extrinsic information transfer chart is utilized to help analyze and design the optimal bit mapping. Bit error rate simulations are carried out to verify the superiority of the proposed MIMO system.

Compared with standard cyclic prefix OFDM (CP-OFDM), time domain synchronous OFDM (TDS-OFDM) can achieve a higher spectrum efficiency by using the known training sequence instead of CP as the guard interval. However, TDS-OFDM suffers from reduced energy efficiency and performance loss due to the existing mutual inferences. In this paper, based on the newly emerging theory of structured compressive sensing (SCS), we propose a reliable and energy-efficient TDS-OFDM transmission scheme with reduced guard interval power (which is impossible for CP-OFDM) by designing a channel estimation scheme with high accuracy. The wireless channel properties including channel sparsity and inter-channel correlation, which are usually not considered in conventional OFDM schemes, have been exploited. We further exploit the worst-case system design principle to extract multiple interference-free regions of small size to simultaneously reconstruct multiple channels of large size without iterative interference cancellation. In this way, the guard interval power in TDS-OFDM can be reduced to achieve a 20% higher energy efficiency than standard CP-OFDM, and the system reliability can be also improved in fast fading channels.

Digital video broadcasting-next generation handheld (DVB-NGH) is the first broadcasting standard that incorporates multiple-input multiple-output (MIMO) techniques to overcome the Shannon limit of single antenna systems. This paper contributes to analyze the performance of the DVB-NGH MIMO coded modulation system. The detailed performance degradation from information-theoretic limit to implementation by average mutual information and extrinsic information transfer analysis is presented, which provides an insight guideline for future system improvement. Finally, bit error rate simulations are carried out to verify the analysis.

A polar decomposition of mutual information between a complex-valued channel's input and output is proposed for an input whose amplitude and phase are independent of each other. The mutual information is symmetrically decomposed into three terms: 1) an amplitude term; 2) a phase term; and 3) a cross term, where the cross term is negligible. Theoretical bounds of the amplitude and phase terms are derived for additive white Gaussian noise channels with Gaussian inputs. This decomposition is applied to amplitude phase shift keying with product constellation (product-APSK) design and analysis. It facilitates the product-APSK to achieve a considerable shaping gain at some interesting rates over conventional quadrature amplitude modulation with a similar low complexity.

Doping technique was employed to remove the high error floor in conventional bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID). This paper proposes a new look of the doping technique-BICM-ID with serial concatenated convolutional code (SCCC-BICM-ID). Unlike conventional doping decoding scheme which deems the doping decoder and the demapper as a whole doped demapper, we combine the doping code and the outer convolutional code together to form an SCCC, so that iterative demapping and decoding is performed between the demapper and the SCCC decoder. Extrinsic information transfer (EXIT) chart is used to analyze these two decoding schemes and reveals that they both can achieve near-capacity performance with no penalty of error floor. According to the results of EXIT analysis and BER simulations, SCCC-BICM-ID system can achieve the same or even better performance compared to the doping BICM-ID system with lower decoding complexity.

Physical-layer security could efficiently prevent wiretapping for wireless communication from the information-theoretic perspective. However, most related works in this area are based on the assumption of Gaussian inputs, which are impractical for a practical communication system. In this paper, we study the physical-layer security with finite-alphabet inputs, wherein amplitude phase shift keying (APSK) constellation is considered to improve the achievable secrecy rate performance. It is concluded that the secrecy rate can be improved by using APSK, comparing to its quadrature amplitude modulation (QAM) counterpart, which is verified by both the minimum mean square error (MMSE) theoretic derivation and simulation results. A specific strategy of selecting constellation orders for secure communication is also presented.

Large-scale orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) is a promising candidate to achieve the spectral efficiency up to several tens of bps/Hz for future wireless communications. One key challenge to realize practical large-scale OFDM MIMO systems is high-dimensional channel estimation in mobile multipath channels. In this paper, we propose the time-frequency training OFDM (TFT-OFDM) transmission scheme for large-scale MIMO systems, where each TFT-OFDM symbol without cyclic prefix adopts the time-domain training sequence (TS) and the frequency-domain orthogonal grouped pilots as the time-frequency training information. At the receiver, the corresponding time-frequency joint channel estimation method is proposed to accurately track the channel variation, whereby the received time-domain TS is used for path delays estimation without interference cancellation, while the path gains are acquired by the frequency-domain pilots. The channel property that path delays vary much slower than path gains is further exploited to improve the estimation performance, and the sparse nature of wireless channel is utilized to acquire the path gains by very few pilots. We also derive the theoretical Cramer-Rao lower bound (CRLB) of the proposed channel estimator. Compared with conventional large-scale OFDM MIMO systems, the proposed TFT-OFDM MIMO scheme achieves higher spectral efficiency as well as the coded bit error rate performance close to the ergodic channel capacity in mobile environments.

Time domain synchronous OFDM (TDS-OFDM) has higher spectral efficiency and faster synchronization than standard cyclic prefix OFDM (CP-OFDM), but suffers from the difficulty of supporting 256QAM in low-speed vehicular channels with long delay spread and the performance loss over fast time-varying vehicular channels. This paper addresses how to efficiently use the compressive sensing (CS) theory to solve those problems. First, we break through the conventional concept of cancelling the interferences if present, and propose the idea of using the inter-block-interference (IBI)-free region of small size to reconstruct the high-dimensional sparse multipath channel, whereby no interference cancellation is required any more. In this way, without changing the current signal structure of TDS-OFDM at the transmitter, the mutually conditional time-domain channel estimation and frequency-domain data detection in conventional TDS-OFDM receivers can be decoupled. Second, we propose the parameterized channel estimation method based on priori aided compressive sampling matching pursuit (PA-CoSaMP) algorithm to achieve reliable performance over vehicular channels, whereby partial channel priori available in TDS-OFDM is used to improve the performance and reduce the complexity of the classical CoSaMP signal recovery algorithm. Simulation results demonstrate that the proposed scheme can support the 256QAM and gain improved performance over fast fading channels.

There has been an explosion in mobile data traffic, but cellular networks alone could not support the fast growing demand on data transmission. This dilemma is caused mainly by the reason that the same content is repeatedly transmitted in the network, since many people are interested in the same content. Broadcast networks, however, could alleviate this problem by delivering popular content to multiple clients simultaneously. This paper presents a content dissemination system combining broadcast network with cellular network. Based on the model of Markov Decision Process, we propose an online optimal scheme to maximize the expected number of clients receiving content. The clients' interest and queuing length at broadcast and cellular base stations are two important elements that are considered in our scheme. Simulation results demonstrate that, compared with random scheme and single network scheme, our scheme performs the best in terms of lowering packet loss rate at base stations and enhancing the average number of clients who receive their interested content.

Wireless traffic has two features: people have common interests in the hottest contents, and a large amount of traffic belongs to non-realtime services. Exploiting these two features, we propose a content dissemination system, integrating broadcast network and opportunistic network. In the proposed system, popular contents are broadcasted through broadcast network and then disseminated to users through opportunistic network. Such system can significantly reduces the same contents repeated transmission and efficiently delivers contents to their clients. Using a Markov model, we theoretically analyze content dissemination delay of the proposed system.

3GPP long term evolution (LTE) Turbo coded modulation is well-known for its excellent error-control capability. However, its decoding threshold is still a few decibels away from the constellation-constrained capacity. In this paper, an irregular mapping scheme involving labeling search is proposed to improve the performance of the LTE system. The scheme first predetermines one labeling, and then searches the other one via adaptive binary switch algorithm (ABSA), which considerably increases the design freedom and can provide near-optimal match to a given channel code. By applying the scheme to the LTE specification (Release 8), a practical bit-interleaved Turbo coded modulation with iterative demapping and decoding (Turbo-BICM-ID) system is proposed. With a slight modification on the constellation mapping, the scheme can lower the signal-to-noise ratio (SNR) threshold by 0.43~0.48dB at the block error rate (BLER) of 10-2under different channel conditions.

Orthogonal frequency division multiplexing (OFDM) is widely recognized as the key technology for the next generation broadband wireless communication (BWC) systems. Besides high spectral efficiency, reliable performance over fast fading channels is becoming more and more important for OFDM-based BWC systems, especially when high speed cars, trains and subways are playing an increasingly indispensable role in our daily life. The time domain synchronous OFDM (TDS-OFDM) has higher spectral efficiency than the standard cyclic prefix OFDM (CP-OFDM), but suffers from severe performance loss over high speed mobile channels since the required iterative interference cancellation between the training sequence (TS) and the OFDM data block. In this paper, a fundamentally distinct OFDM-based transmission scheme called time-frequency training OFDM (TFT-OFDM) is proposed, whereby every TFT-OFDM symbol has training information both in the time and frequency domains. Unlike TDS-OFDM or CP-OFDM where the channel estimation is solely dependent on either time-domain TS or frequency-domain pilots, the joint time-frequency channel estimation for TFT-OFDM utilizes the time-domain TS without interference cancellation to merely acquire the path delay information of the channel, while the path coefficients are estimated by using the frequency-domain grouped pilots. The redundant grouped pilots only occupy about 3% of the total subcarriers, thus TFT-OFDM still has much higher spectral efficiency than CP-OFDM by about 8.5% in typical applications. Simulation results also demonstrate that TFT-OFDM outperforms CP-OFDM and TDS-OFDM in high speed mobile environments.

Amplitude phase shift keying (APSK) constellation is capable of outperforming quadrature amplitude modulation (QAM) in terms of both the mutual information and the error-control performance. However, the lack of simplified demapper prevents its potential applications due to the inherent high computation complexity. In this paper, the concept of APSK using product constellation labeling is introduced, and two simplified demappers are proposed. Theoretical analysis and simulations show that the performance degradation caused by these simplified demappers is negligible, while the complexity is significantly reduced, compared to the traditional Max-Log-MAP demapper.

Bit-interleaved coded modulation with iterative demapping (BICM-ID) is investigated for multiple-input multiple-output (MIMO) channels. Based on the average mutual information (AMI) analysis, vertical Bell-lab layered space-time (V-BLAST) rather than space-time block code (STBC) is chosen to be combined with BICM-ID. Based on the extrinsic information transfer (EXIT) chart analysis, a novel algorithm in searching for a labeling to well match the outer code is proposed for MIMO channels, which facilitates a near-capacity V-BLAST-BICM-ID scheme. Computer simulation confirmed the near-capacity performance.

Time domain synchronous OFDM (TDS-OFDM) with higher spectral efficiency than cyclic prefix OFDM (CP-OFDM)was originally proposed for downlink broadcasting transmission. To support multi-user uplink scenarios, this paper proposes a novel multiple access scheme called time domain synchronous frequency division multiple access (TDS-FDMA), wherein an uniform frame structure and its corresponding receiver algorithms are presented for both single-carrier and multicarrier signal transmission. Compared with typical OFDMA systems, TDS-FDMA has higher spectral efficiency. The multi-user TDS-FDMA receiver has lower complexity than the conventional single-user TDS-OFDM receiver, and it can achieve better bit error rate (BER) performance under the slow to medium time-varying channels.

Through the investigation on frame header (FH) structures of DTMB system, i.e. the digital terrestrial television broadcasting standard of China, spectrum sensing methods based on PN cross-correlation (PNCC) are proposed for all FH options. Miss-detection probability, decision threshold and sensing time requirement of the proposed methods are analyzed in detail. Comparisons on spectrum sensing performance, robustness to time dispersive channel and carrier frequency offset are made between the proposed methods and the existing methods based on PN autocorrelation (PNAC). Both theoretical analyses and simulation results demonstrate the considerable advantage of the proposed PNCC methods over the existing PNAC methods.

To efficiently suppress the noise through a time-domain threshold value after the least square (LS) estimation, the discrete Fourier transform (DFT) based channel estimation (CE) is usually carried out in practical orthogonal frequency division multiplexing (OFDM) systems for its inherent noise immunity. In this paper, an improved DFT based CE method for OFDM systems is proposed. Taking advantage of the wavelet decomposition, the proposed method obtains an optimal threshold value according to the minimum mean-square error (MMSE) optimality criterion. Both theoretical analysis and computer simulation show that, the proposed method not only reduces the mean-square error (MSE) without MSE floor compared with the conventional methods, but also improves the symbol error rate (SER) performance by being more close to that of the ideal known-channel case over both static and dynamic multipath channels.

Cochannel interference has been the bottleneck to the capacity of cellular network. To solve this issue, a virtual multiple-input multiple-output (MIMO) system can be constructed for the uplink OFDMA cellular system. However, if multiple cochannel MIMO clusters are used, they will still interfere with each other. Capacity of this virtual MIMO system in cellular networks with cochannel interference is derived and simulated. The influence of some parameters to the system capacity are studied, including path loss component, transmit power, the radius of cell and the number of antennas in base stations. Simulation results show that if only the first 1 neighbor layer of cochannel cells are considered, the virtual MIMO capacity will be greatly larger than that of the single-input single-output (SISO) system with universal frequency reuse. However, the cochannel interference can greatly reduce the virtual MIMO capacity in the uplink cellular system compared with the interference free environment. Thus interference cancellation techniques are required to be developed in the future.

This paper summarizes some key features for future Chinese digital television terrestrial broadcasting (DTTB) systems including improved frame structure, transmit diversity, advanced channel coding and modulation, multi-service support, broadcasting return channel solution and etc.

Time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) outperforms cyclic prefixed-OFDM (CP-OFDM) in spectrum efficiency at the expense of higher complexity. Up to now, TDS-OFDM has only been used in unidirectional transmission, such as broadcasting applications. The overwhelming complexity of removing the implicitly superposed interferences between the PN sequences and IDFT information blocks, caused by multiple users, hinders the application of time-domain synchronous orthogonal frequency division multiple access (TDS-OFDMA) in multi-user communication scenarios. To solve this problem, this paper proposes a novel TDS-OFDMA scheme, including joint cyclicity reconstruction and joint channel estimation, utilizing the new "time-space two-dimensional frame structure". Theoretical analysis and computer simulation show that the proposed scheme not only can achieve the purpose of multiple access but also has an even better system performance in mobile environment than the conventional single-user TDS-OFDM system.

To improve the overall performance of time-domain synchronous (TDS) orthogonal frequency division multiplexing (OFDM) systems, novel iterative decoding and channel estimation algorithm with Nordstrom-Robinson (NR) code is proposed in this paper. Compared to the non-iterative case, the system performance can be significantly improved by the proposed iterative algorithm at the cost of a little complexity and latency increase. Simulation results show that, for example, with maximum Doppler spread of 25 Hz under two typical multipath channels at bit error rate (BER) of 10-4, the signal to noise ratio (SNR) performance of the proposed iterative algorithm is only 0.2 to 0.3 dB away from the ideal case, and about t dB or more better than the non-iterative one.

It is well known that the cyclic property of transmitted signal can be used to achieve joint frame and carrier frequency synchronization, while the uncompensated sampling frequency offset (SFO) would still be a problem. Based on the observation that the impact of SFO on the received cyclic block and its replica is equivalent to a relative time shift, a joint synchronization scheme solely based on cyclic property is proposed to achieve frame, sampling frequency and carrier frequency synchronization simultaneously. A two-dimensional sliding-window auto-correlator (2D-SWAC) is presented to implement the joint synchronization with low complexity. The proposed scheme is suitable for any transmission system with similar cyclic property. Meanwhile, it is robust to large sampling and carrier frequency offset and strong channel frequency selectivity, as demonstrated by the analysis and simulations.

Bit-interleaved coded modulation (BICM) is a sub- optimal scheme from the average mutual information (AMI) point of view due to independent demapping. However, this AMI loss can be neglected for signal constellations with Gray mapping at high coding rates. AMI of amplitude-phase shift keying (APSK) constrained additive white Gaussian noise (AWGN) channel is provided in this paper, which shows that the BICM scheme has considerable loss with APSK constellations since no Gray mapping exists. Bit-interleaved low-density parity-check (LDPC) coded modulation (BILCM) is an excellent scheme and has been employed in many broadcasting and communication systems, however, such scheme also suffers from the independent demapping loss. Therefore, BILCM with iterative demapping and decoding (BILCM-ID) is proposed in this paper to overcome such loss. Simulation results show that the BILCM-ID scheme outweighs BILCM scheme by about 0.5 and 0.3 dB over AWGN channel for 32-APSK constellation at coding rates 2/3 and 4/5, respectively.

In order to improve the system performance over wireless fading channel, transmit diversity technique has been proven as an attractive and effective solution especially for broadcasting systems. In this paper, a PN sequence design scheme based on both cyclic-shift m-sequences and space-time block coded (STBC) m-sequences for time domain synchronous orthogonal frequency-division multiplexing (TDS-OFDM) system with transmit diversity is proposed. Based on this novel design, flexible channel estimation which provides a trade-off between maximum delay spread and maximum Doppler spread over double-selective channel is investigated and a radix-2 fast Fourier transform (FFT) approach is adopted for implementation from the viewpoint of computational complexity. Simulations show that the performance of the proposed transmit diversity scheme is better than conventional one and perform well under different propagation conditions.

In order to improve the system performance over both frequency- and time-selective fading channels, orthogonal frequency division multiplexing (OFDM) system with transmit diversity technique is an effective and attractive solution. However, the received signal is the superposition of the signals from different transmit antennas. Hence, to obtain accurate channel state information (CSI) is difficult but very important to recover transmitted OFDM symbols. Conventional channel estimation methods use subcarrier pilots or training sequences as the channel sounding signal to obtain the estimation of channel frequency response (CFR). Actually, decision-directed channel estimation (DDCE) method which takes advantage of the fact that m-QAM constellation subcarriers in OFDM symbol also contain much valuable hidden-information and can be used to perform the channel estimation as well as tracking of time-varying channel. In this paper, a simple and effective partial hard decision method for m-QAM is investigated. Furthermore, a simplified DDCE method based on an accurate initial CFR and partial decision results of OFDM subcarriers for transmit diversity system is proposed. Simulation results demonstrate that the proposed algorithm works well over the slow-varying frequency-selective fading channel.

Accurate channel estimation is essential for coherent signal transmission. This paper presents a novel channel estimation algorithm for time-domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) systems with identical pseudo-noise (PN) sequence padding. Simple cyclic reconstruction and tail cancellation methods are proposed to estimate the channel impulse response (CIR). Phase equalization and partial hard decision on the received data symbols are used to improve the estimation performance. Simulation results show that the proposed channel estimation algorithm brings good BER performance (approaching the ideal case) with fast convergence (no iteration required) over frequency-selective slowly fading channels.

This study proposes an iterative channel impulse response (CIR) estimation scheme for multicarrier block transmission with known symbol padding, in the context of the time-domain synchronous OFDM (TDS-OFDM) system. It is shown that the TDS-OFDM still fulfils the circular convolution relationship even if pseudo-noise (PN) sequence is used as guard interval. While conventional methods perform the channel estimation based on the cyclic prefix reconstruction or residual intersymbol interference cancellation in the time domain, by processing the data part and the known symbol padding in one TDS-OFDM block separately, the new proposal uses the one- tap frequency-domain equalization to separate the data part and the known symbol padding and the CIR can be estimated in an iterative manner. In a typical example for 3780-point FFT based TDS-OFDM system with 16QAM constellations, the mean square error (MSE) of of the proposed channel estimator can be reduced to about 10-5/2 after two iterations when the channel signal-to-noise ratio (SNR) is larger than 8 dB, without the initial CIR estimation. The BER performance of a QPSK TDS-OFDM system shows that the signal-to-noise-ratio (SNR) degradation based on the proposed channel estimator is less than 0.3 dB compared with the lower bound for both Brazil A and B channels.

As one of the most common linearization techniques, adaptive digital predistortion minimizes the difference between the input signal of the predistorter and the feedback signal from the power amplifier. The loop delay between these two signals must be controlled precisely so that the convergence of the predistorter should be assured. In this paper a novel two-stage loop delay correction scheme is presented. In the first stage, the integer delay between the input signal and the feedback signal is estimated based on the cross-correlation of them. In the second stage, the fractional delay between these two signals are corrected by a delay lock loop (DLL) circuit, in which a novel timing error detector used as the discriminator is proposed. The proposed loop delay correction scheme is applied to an adaptive digital predistorter in an orthogonal frequency-division multiplexing (OFDM) system. Simulation results show that the proposed loop delay correction method eliminates the loop delay perfectly, so that nearly optimal power spectral density (PSD) performance is achieved and a high degree of linearization is realized.

The implementation of OFDM system suffers from the effect of phase noise generated by local oscillator (LO), which disturbs the orthogonality between subcarriers and causes intercarrier interference (ICI). In this paper, the symmetric conjugate-negative property of the ICI weighting function is found. Based on that, the ICI self-cancellation of symmetric data-conjugate method is studied to suppress phase noise. The carrier-to-interference ratio (CIR) improvement by this method is shown to be larger than 22 dB in flat fading channel. For a BER of 10-3, this method can tolerate a phase noise standard deviation of 7 deg in flat fading channel. Moreover, this method could offer frequency diversity gain in frequency selective channels. Both analytical and numerical results show that this method outperforms the conventional schemes

Multiple amplitude shaped offset quadrature phase-shift keying (MA-SOQPSK) modulation based on multiple nonlinear power amplifiers (NLPAs) provides both high power-added efficiency and spectrum efficiency. However, the phase misalignment between the different branches of MA-SOQPSK signal in the process of the modulation can significantly degrade the bit-error-rate (BER) performance. A novel scheme of correcting this phase error is proposed in this paper, which contains a phase lock loop (PLL) in the modulation terminal. Theoretical estimation and simulation on the variance of the phase error are also given to validate our method. The BER simulation result shows that our scheme improves the performance more than 3 dB at 10"3, and the improvement becomes more distinct as the SNR.

With the introduction of the Modified Matched Filter method, we first present a novel blind maximum-likelihood timing recovery approach for the all-digital receivers suffering from carrier frequency offset. Then a suboptimum version, equivalent to the Gardner timing recovery loop employing the matched filter instead and independent of the frequency offset estimation, is derived to reduce the computational complexity. Moreover, a Mismatch criterion is introduced for the suboptimum simplification to provide the carrier-frequency-offset range in which it suffers negligible steady-state performance degradation and facilitate the system design. The effectiveness of these two methods as well as the validity of the Mismatch criterion are demonstrated through simulations.

The distributed radio transmission scheme can improve signal coverage, as the Single Frequency Network (SFN) for DTV broadcasting. However, the propagation characteristics of the distributed transmission in SFN have to be studied carefully for they are different from conventional single transmission cases. In this paper, the field measurement carried out in a rural SFN with two synchronized transmitters is reported. It is found that, on the one hand, the radio signal coverage of the distributed transmission scheme has been distinctly improved with the total transmitted power by multi-transmitters as same as compared single transmitter system; and, on the other hand, the power delay profile (PDP) has shown rather different features than the single transmission cases, in which there are long delay "echoes" and could not be modeled simply by exponential decays because of the existence of distributed transmitters. The parameter called "transmission gain" has been introduced in order to extend the concept of "path gain" to the distributed transmission cases and, the tapped delay line is used to model the average PDP in the distributed transmission cases.

The learning algorithm for complex-bilinear recurrent neural network (C-BLRNN) derived in the paper referenced in the title is incorrect. The correct derivation, which follows the method in two other literatures, is presented.

To improve the transmission performance of terrestrial digital multimedia/television broadcasting (DMB-T) system, the performance of an efficient space-frequency transmitter diversity scheme is introduced in this article. This scheme maintains the original transmitter branch and the network structure is simple to upgrade. DMB-T system is an important candidate for Chinese digital television terrestrial broadcasting (DTTB) standard. The system was simulated over both slow and fast fading DTTB channels. Simulation results show that the introduced transmitter diversity scheme can efficiently improve the system performance in fading environments.

Abstract Wireless communications for mobile telephone and data transmission is currently undergoing very rapid development. Code division multiple‐access (CDMA) implemented with direct sequence spread spectrum signaling is among the most promising multiplexing technologies for cellular telecommunications services. In this paper, jointly period inserted pilot symbols assisted recursive (PIPSAR) channel estimation and interference suppression techniques are proposed for uplink CDMA mobile communication systems. The uplink CDMA mobile communication system model is described in the form of space‐time domain through antenna array and multipath expression. Interference suppression is achieved by using adaptive minimum mean squared error (MMSE) digital filters that span several successive received chip oversampling vectors of a symbol interval. PIPSAR techniques are used to estimate channel parameters. The correlation between the successive periods is considered to further improve the performance of the proposed scheme. Analysis and simulations are used to evaluate the performance of the proposed scheme. Copyright © 2004 John Wiley & Sons, Ltd.

Techniques are proposed for interference suppression for the uplink of multiuser CDMA systems. The multiuser CDMA uplink communication system model is described in space-time domain form through an antenna array and a multipath expression. A linear prediction technique is used to perform channel estimation. Based on the estimated channel state information, constrained minimum power digital filters are used to suppress interference. The prefiltered multipath signals from all antennas are combined to get the final decision statistic. The correlation between the successive periods is considered to improve further the performance of the proposed scheme. Simulations demonstrate the effectiveness of the proposed scheme.

In this paper high-coding-rate block turbo codes (BTC) are adopted in digital television terrestrial broadcasting (DTTB) to replace the conventional applications of serially concatenated codes. A new multi-resolution 64QAM constellation is designed for hierarchical modulation to offer three tiers of services with dedicated protection in one DTTB channel. In the receiver, the simulation result on fixed-point iterative turbo decoding algorithm based on MAX-LOG-MAP criterion is aided to develop the ASIC core. Simulation in terms of bit-error-rate (BER) on additive white Gaussian noise channel shows that the required E/sub b//N/sub O/ High priority stream is only 3.9 dB at the threshold of visibility, which makes it more competent for mobile and indoor reception or other error-sensitive services. At the same time, the medium and low priority streams can support fixed outdoor reception.

In many physical channels, such as urban and indoor radio channels, the ambient noise is known through experimental measurements to be decidedly non-Gaussian, which makes the system performance degradation under non-Gaussian channels for those only utilizing the conventional Gaussian interference suppression scheme. In this paper, a robust multi-stage nonlinear interference suppression scheme is developed for synchronous DS-CDMA system under either Gaussian or non-Gaussian noise channels. For the DS-CDMA systems, simulation results show that the proposed scheme not only has nearly the same performance with the classical Gaussian interference suppression scheme under Gaussian noise channels, but also offers significant performance gain over the classical Gaussian interference suppression scheme under non-Gaussian noise channels.

Orthogonal frequency-division multiplexing (OFDM) is extensively used in modern terrestrial digital television broadcasting systems to support high performance bandwidth-efficient multimedia services. Cutoff rate and outage probability are two important criterions to evaluate the performances of a practical communication system in radio engineering. In this paper, the cutoff rate and outage probability performances are compared between two important terrestrial digital television broadcasting systems, the cyclic prefix OFDM based DVB-T system and the time domain synchronous OFDM based DMB-T system, under different multipath channel conditions.