Hu Jianhao

RNS based OFDM transmission scheme with low PAPR

One of the main limitations for OFDM-based transmission systems is the high Peak-to-Average Power Ratio (PAPR) of the transmitted signals. In this paper, the residue number system (RNS) based OFDM transmission scheme is proposed to reduce the PAPR, which uses the features of RNS to control the dynamic range of the transmitted signals and avoid the nonlinear distortion for the PAPR reduction. Experimental results show that at least 5dB of PAPR performance is improved with the proposed method, compared with the original OFDM.

Low-complexity single-channel blind source separation

Abstract For the time-frequency overlapped signals, a low-complexity single-channel blind source separation (SBSS) algorithm is proposed in this paper. The algorithm does not only introduce the Gibbs sampling theory to separate the mixed signals, but also adopts the orthogonal triangle decomposition-M (QRD-M) to reduce the computational complexity. According to analysis and simulation results, we demonstrate that the separation performance of the proposed algorithm is similar to that of the per-survivor processing (PSP) algorithm, while its computational complexity is sharply reduced.

Blind interference detection and recognition for the multi-carrier signal

Abstract For the interference hidden in the expected multi-carrier signal, this paper proposes a novel detection and recognition algorithm. The algorithm cannot only detect the single-carrier interference (SCI) by the high-order cumulant, but also finds the multi-carrier signal based on spectrum character. Besides, the algorithm can distinguish the modulation types of the SCI. The algorithm does not depend on any prior knowledge and data-aided, which is propitious to practical applications. The analysis and simulation results demonstrate that the proposed algorithm is effective.

A systemic performance estimation and moduli set selection method for residue number systems

The residue number system (RNS) has been receiving considerable attention for many decades owing to its inherent carry-free and parallel properties in addition, subtraction, and multiplication operations. In RNS-based systems, the method by which the moduli set is selected and evaluation of its performance are important issues. A systemic performance evaluation method for RNS based on the properties of the moduli set is proposed in this paper. By abstracting the inherent properties of moduli sets, such as the complexity of arithmetic units, utilization ratio of dynamic range, parallelism, and balance between residue channels, information can be provided on moduli set selection and performance estimation before circuit implementation. Furthermore, we also propose a new multi-channel moduli set that utilizes a new radix component in this paper. Performance analysis and comparison results show that the proposed multi-channel moduli set has good systemic performance.

Timing performance for MRF-based circuits with low supply voltage

Markov Random Field (MRF) based design methodology presents a new approach to establish high noise-immune structure for ultra-low power circuit designs. The MRF design technique is able to significantly improve the reliability and interference tolerance of the logic circuits. The main idea of this methodology is that the circuit has the highest likelihood for correct logic states from the viewpoint of joint probability distribution. At present, the researches of MRF-based circuit designs focus on the circuit structure and noise tolerant performance analysis for ultra-low supply voltage applications. But there is no investigation on the timing performance of MRF-based circuits. In this paper, we simulated different well-known structures of the fundamental MRF-based elements with HSPICE, and measured the corresponding propagation delay and transition time to evaluate the timing performance of circuit. From the measurements, we find that the propagation delay of MRF-based circuits is one order bigger than that of the traditional (complementary metal oxide semiconductor) CMOS circuits, but MRF-based circuits can achieve similar transition time with traditional CMOS circuits.

A new time delay estimation algorithm for mixed OFDM signal

In the paper, a new time-delay estimation algorithm, which is based on the cyclic auto-correlation function, is proposed for single-channel two mixed OFDM signals without data-aided. In the method, the linear equations on time delay parameters are constructed from different cyclic autocorrelation functions, and the closed-form solutions are obtained by solving the equations without any prior information of fading parameter and shaping filter. Besides, it also analyzes the Cramer-Rao bound of time-delay estimation of mixed OFDM signal, and verifies the effectiveness of the proposed method through computer simulation. The analysis and simulation results show that the proposed algorithms can achieve good blind estimation for the time delay of mixed OFDM signal in a single channel.

High efficient modulo 2 n −2 k −1 adder VLSI design and implementation for RNS

The design of high efficient modulo adders is important for the implementation of DSP algorithms based on Residue Number System (RNS). Moduli sets with this form 2n-2k-1 offer many advantages, such as larger dynamic range and excellent balance among the RNS channels. In this paper, a general algorithm and its VLSI implementation structure are proposed for modulo 2n-2k-1 adder. The proposed algorithm is based on the techniques of prefix operation and carries correction, which eliminates the re-computation of carries. And any existing prefix operation structure can be adopted in the proposed structure. Compared with the same modulo adders with different structures, the proposed modulo 2n-2k-1 adder offers better area*delay.

Energy performance of OOFSK and FSK for wireless sensor networks

Wireless sensor networks (WSNs) nodes are usually battery powered, which becomes the bottleneck of their widespread applications. Therefore the design of low power consumption for WSNs has drawn great attention among researchers. Since the WSN transmission scheme largely determines the energy performance of the entire networks, we introduce two efficient modulation scheme-Frequency shift key (FSK) and On-Off Frequency shift key (OOFSK) into WSNs. In order to analyze and compare the energy performance between the two different transmission schemes, we establish a basic communication model and obtain their energy performance indicators as well as the variable trend of the indicators. The numerical results reveals that the OOFSK transmission can achieve a better energy performance than the FSK transmission with low signal to noise ratio and small OOFSK modulation duty cycle. In the further analysis of simulation results, different application situations of OOFSK and FSK are discussed and concluded, which has positive effect on modulation scheme design of low power consumption WSNs.

Channel estimation design for Air-ground OFDM Data Link

To fulfill future airport capacity requirements, the proposed data link has to be a high capacity, high rate data link. Air-ground Data Link System can be used in orthogonal frequency division multiplexing (OFDM) systems to improve communication quality and capacity. A channel estimation design method for OFDM system by using correlation of pilot sequences has been proposed in this paper. The main point of this algorithm is the autocorrelation of the sequences. This paper presents a method for optimum training sequences design and the channel estimation implementation that follows. By using these training sequences, in frequency domain, we can get the channel frequency response easily; in time domain, we can get the data fading which are between the adjacent pilot training symbols by some means of interpolation. Simulation and implementation results indicates that this method can obtain good system performance and with low complexity.