To realize transmit diversity for the time domain synchronous OFDM (TDS-OFDM) system, this letter proposes the space-time-frequency orthogonal training sequence and the corresponding flexible channel estimation methods. Simulation results indicate that an significant performance improvement could be achieved for low-density parity-check code (LDPC) coded TDS-OFDM system over multi-path fading channels.

This letter presents a flexible signal structure supporting localization service for time domain synchronous OFDM (TDS-OFDM) in multi-service transmission applications. Localization is treated as one specific service and the corresponding data is allocated within the physical layer pipe (PLP) of the first subframe. The concept of variable sub-carrier spacing to combat Doppler spread is also introduced for the localization service. Simulation results indicate that the proposed scheme outperforms the conventional scheme and at the same time achieves high positioning accuracy.

This letter presents a novel multi-carrier code division multiple access (MC-CDMA) system called time domain synchronous MC-CDMA (TDS-MC-CDMA). Aided by the new training sequence (TS) with perfect autocorrelation in the time domain and flat frequency response in the frequency domain, the proposed TDS-MC-CDMA system outperform the traditional MC-CDMA system in terms of spectrum efficiency by about 10%. Simulations are carried out to demonstrate the good performance of the proposed scheme.

A BICM-ID system with 3-dimensional rotated BPSK constellation and signal space diversity (SSD) is proposed to combat the effect of Rayleigh fading. A new criterion based on mutual information is proposed to find the optimal rotation matrix, and the labeling that fits well with the outer code is presented. Simulation results show that at BER of 10-5 over a Rayleigh fading channel, with the code length of 192,000 bits and the iteration number of 100, the performance of the proposed system is only about 0.8 dB from the Gaussian-input Shannon limit and exceeds the limit constrained by the traditional QPSK input without rotation or SSD, at the spectrum efficiency of 1 bit/s/Hz.

There has been an explosion in wireless devices and mobile data traffic, and cellular network alone is unable to support such fast growing demand on data transmission. Therefore, it is reasonable to add another network to the cellular network to augment the capacity. In fact, the dilemma of cellular network is mainly caused by that the same content is repeatedly transmitted in the network, since many people are interested in the same content. A broadcast network, however, could mitigate this problem and save wireless bandwidth by delivering popular content to multiple clients simultaneously. This paper presents a content dissemination system that combines broadcast and cellular networks. Using the model of Markov Decision Process (MDP), we propose an online optimal scheme to maximize the expected number of clients receiving their interested content, which takes clients' interests and queuing length at broadcast and cellular base stations into full consideration. Simulations demonstrate that the proposed scheme effectively decreases item drop rate at base stations and enhances the average number of clients who receive their interested content.

A method to construct bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) is developed that approaches the Shannon limit very closely at high spectrum efficiency, where amplitude-phase shift keying (APSK) constellations are designed and chosen. For 1/2-rate 64APSK, the Es/N0 threshold derived through extrinsic information transfer (EXIT) charts is less than 0.55 dB away from the Shannon limit of the continuous-input additive white Gaussian noise (AWGN) channel, and exceeds the theoretical limit constrained by standard 64QAM-input.

In this letter, a novel physical layer signaling transmission scheme is proposed, where the signaling information is conveyed by a pair of training sequences located in the odd and even subcarriers of an orthogonal frequency division multiplexing (OFDM) training symbol. At the receiver side, only a single correlator is required to detect the signaling information. Computer simulations verify the proposed signaling could outperform the S1 signaling and achieve similar robustness as the S2 signaling of the DVB-T2 standard.

This paper proposes a novel scheme to reduce the complexity of existing transmit diversity solutions to time domain synchronous OFDM (TDS-OFDM). The space shifted constant amplitude zero autocorrelation (CAZAC) sequence based preamble is proposed for channel estimation. Two flexible frame structures are proposed for adaptive system design as well as cyclicity reconstruction of the received inverse discrete Fourier transform (IDFT) block. With regard to channel estimation and cyclicity reconstruction, the complexity of the proposed scheme is only around 7.20% of that of the conventional solutions. Simulation results demonstrate that better bit error rate (BER) performance can be achieved over doubly selective channels.

The next generation wireless broadcasting systems combining with MIMO technology has drawn much attention recently. Considering the coexistence of receivers equipped with different numbers of antennas in these systems, there exists the special requirement to maximize the transmission rate for receivers having more antennas, while guaranteeing the normal rate for receivers having less antennas. In this letter, superposition coding is proposed to fulfill this requirement and the concept of broadcast cluster is introduced, wherein the optimized power allocation parameters are derived. The BER simulations for multiple services are provided to verify the significant SNR performance gap between receivers with various numbers of receive antennas.

This paper presents an efficient multi-service allocation scheme for the digital television terrestrial broadcasting systems in which the fixed service is modulated by orthogonal frequency division multiplexing and quadrature amplitude modulation (OFDM/QAM) with larger FFT size and the added mobile service is modulated by OFDM and offset quadrature amplitude modulation (OQAM) with smaller FFT size. The two different types of services share one 8MHz broadcasting channel. The isotropic orthogonal transform algorithm (IOTA) is chosen as the shaping filter for OQAM because of its isotropic convergence in time and frequency domain and the proper FFT size is selected to maximum the transmission capacity under mobile environment. The corresponding transceiver architecture is also proposed and analyzed. Simulations show that the newly added mobile service generates much less out-of-band interference to the fixed service and has a better performance under fast fading wireless channels.