- [Show abstract] [Hide abstract] ABSTRACT: In the current study, using methods of signal processing to manage gene prediction has attracted great attention. At first, the voss mapping which can map the DNA alphabetic sequence into the numerical sequence and the 3-base periodicity of exon are introduced. Then a fixed-length sliding window approach and its feasibility are analyzed. It can be proved that when two exons are very close, gene prediction by only setting a threshold to the spectrum could not have good effect. To overcome this shortcoming, a new method based on one-dimensional image segmentation is proposed. Finally, simulation shows the short introns are culled commendably. Two evaluation indices are also introduced to demonstrate the effectiveness of this method.
- [Show abstract] [Hide abstract] ABSTRACT: Modulation recognition, as a key technology, plays an important role in improving performance of spectrum sensing in cognitive radio. Considering needs of practical engineering, the paper firstly proposes a set of feature parameters based on instantaneous information. Then it simulates and analyzes infection to parameters extraction aroused by symbol shape. Simulation results show that new feature parameters extracted are steady and have clear distinction towards modulation signals. The paper, with new feature parameters extracted, achieves purposes of recognition of modulation signals and improves recognition rate of the algorithm.
- [Show abstract] [Hide abstract] ABSTRACT: Smart phones have been ubiquitous in the past few years due to capable of storing data, the Smart phones are now an extremely attractive target for large-scale security attacks. In order to implement the security of Android access control, aim at Android permission access security mechanism, this paper proposes an optimization mechanism for permission access security based on the Android platform. The method divides the Android permission into four categories, analyzes the permission security threat values and takes the free application more likely for malicious application than paid application into consideration, for judging application permission combination security threat level by application security threat value. Experimental results show that the permission access security mechanism can effectively detect malicious applications and enhance the security of Android access control.
Conference Paper: The Study on Synchronization Algorithm in Distributed MIMO-OFDM System[Show abstract] [Hide abstract] ABSTRACT: MIMO-OFDM is an efficient data transmission technology, which has a good anti-fading ability and achieves parallel transmission. The time delay and frequency offset of signals among different receiving and transmitting antenna are not the same in MIMO-OFDM system. And thus the estimation simultaneous of the timing and frequency offset between each transmit and receiving antennas is one of the most challenging parts in MIMO-OFDM system. In the paper, we present a kind of synchronization algorithm based on training sequence. We take advantage of multi-antenna diversity of the algorithm. The performance of MSE about synchronization algorithm gets a significant improvement. The simulation results show that the performance of the proposed synchronization scheme system is still good in the case of relatively low signal to noise ratio (SNR). So it can effectively combat the impact of Rayleigh fading.
- [Show abstract] [Hide abstract] ABSTRACT: In order to solve recognition of modulation signals, which is an important issue in cognitive radio, the paper proposes a new algorithm of recognition of modulation signals. The paper firstly analyzes a new algorithm of cooperative sensing and simulates it in low SNR. Secondly, it proposes new expressions of transient characteristic parameters and shows the procedure of how to define the thresholds. Finally, this paper shows and analyzes the simulation results. The simulation results show that the new algorithm of cooperative sensing has good detection performance. The transient characteristic parameters proposed in the paper have strong anti-noise ability and they can be as robust signatures.
Conference Paper: The Study on an Improved STBC in MIMO-OFDM System[Show abstract] [Hide abstract] ABSTRACT: Compared with space-time block coding (STBC), the improved space-time block coding (ISTBC) enhances data rate transmission, which is more suitable for a broadband high-speed wireless communication. In this paper, combining ISTBC with MIMO-OFDM system can take full advantage of the diversity resources for the system. Firstly, we give the encoding and decoding algorithm of ISTBC. Then, we analyze the system structure for ISTBC-MIMO-OFDM. Finally, simulation, analyses and comparison are performed with the case of different modulation order and different number of sub carriers. Simulation results show that the operated time of ISTBC is shorter than that of STBC in MIMO-OFDM system under the same conditions. The lower modulation order, system performance will be the better. However, the number of sub carriers hardly affects the whole system performance.
- [Show abstract] [Hide abstract] ABSTRACT: As a special class of space-time code, space-time trellis coding (STTC) can achieve the best compromise of coding complexity, performance and bandwidth efficiency. In the paper, we present a MIMO-OFDM system model basing on the STTC. Firstly, we generally describe the framework and the basic principles of the STTC-MIMO-OFDM system. Then simulation is performed under the case of different time delay, different number of paths and subcarriers. Finally, system performance is analyzed and compared in different conditions. Simulation results show that the STTC-MIMO-OFDM system in this paper not only obtains higher diversity gain and coding gain, but also has better bit error rate (BER) performance.
- [Show abstract] [Hide abstract] ABSTRACT: To overcome the weak noise immunity of signals' transient characteristic parameters in domain of modulation recognition, this paper proposes a new expression of transient characteristic parameters and gives the flowchart of recognition program,determination of the thresholds. Thus, ASK2, ASK4, ASK8, PSK2, PSK4, PSK8, FSK2, FSK4 and FSK8 signals can be classified. When SNR=10dB, the average identification probability of 96% can be achieved. The simulations show that transient characteristic parameters with new expression have strong anti-noise ability, they can be as stable and robust signatures.
- [Show abstract] [Hide abstract] ABSTRACT: This paper discuss three synchronization method of MIMO-OFDM Systems whose training sequence base on the CAZAC sequence for distributed systems. First method use the CAZAC sequence, the second and third methods use improved CAZAC sequence. The simulation results shows the accuracy of three methods and the training sequence with changed CAZAC is better than the sequence without change.
- [Show abstract] [Hide abstract] ABSTRACT: The multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) communication systems can provide high data rate. Since channel estimation is an integral part of the receiver designs in coherent MIMO-OFDM systems, it is important to understand the basis of the channel estimation technologies. The basic system models are constructed for the MIMO-OFDM communication systems in this paper. Several non-blind channel estimation technologies, such as the Least Square (LS) algorithm, the Minimum Mean Square Error (MMSE) algorithm and the Singular Value Decomposition (SVD) algorithm are comparatively studied on the MIMO-OFDM communication systems. The simulation results are also provided for the MIMO-OFDM communication systems with different non-blind channel estimation technologies.
- [Show abstract] [Hide abstract] ABSTRACT: Space Time Trellis Code is based on a combination of the delay diversity and the TCM Codes. It is helpful to use Space Time Trellis Code to improve the wireless transmission rate and the reliability. The model, the encoding method and the decoding algorithm of the Space Time Trellis Code systems are discussed in this paper. Then, the trellis of Space Time Trellis Code is analyzed and the coding process of Space Time Trellis Code is specifically explained. Finally, the bit error rate and the frame error rate performances are analyzed, the simulation results are provided for the Space Time Trellis coding systems.
- [Show abstract] [Hide abstract] ABSTRACT: Layered space-time code technique is a good scheme to improve the wireless transmission rate and reliability. The paper discusses four detection algorithms for the Vertical-Bell Laboratories Layered Space-Time (V-BLAST) system. Then, it analyzes the process of algorithms in detail and simulates them. The bit error rate (BER) for the four detection algorithms in different channel situations are compared.
- [Show abstract] [Hide abstract] ABSTRACT: Inter carrier interference (ICI) are widespread in the orthogonal frequency division multiplexing (OFDM) communication systems. This paper mainly discusses two ICI self-cancellation algorithms, the data-conversion based ICI self-cancellation algorithm and the data-conjugate based ICI self-cancellation algorithm. The properties and the application environments are also given. Simulation results show that the performance of the data-conversion based ICI self-cancellation algorithm is superior to the data-conjugate based ICI self-cancellation algorithm in mobile environment, while the data-conjugate based ICI self-cancellation algorithm self-cancellation algorithm has better bit error rate perfomence than the data-conversion based ICI self-cancellation algorithm in small phase noise circumstance. Key words-OFDM; inter carrier interference; data conjugate; data conversion
- [Show abstract] [Hide abstract] ABSTRACT: As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency division multiplexing (OFDM) is extensively used in high-rate wireless communication systems, such as, the wireless local area network (WLAN) and the digital television terrestrial broadcasting (DTTB) systems, to support high performance bandwidth-efficient multimedia services. Multiple antennas and transmit or receive diversity, multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM), can be used to improve error performance and capacity of wireless systems. In this paper, we consider the effects of carrier frequency offset and channel estimation errors on the performance of MIMO-OFDM systems in spatially correlated channels. Theoretical calculations and computer simulations are done to analyze the performance degradation of MIMO-OFDM systems in spatially correlated channels due to carrier frequency offset and channel estimation errors, and the theoretical and simulated results match well. KeywordsChannel estimation–Carrier frequency offset–Multiple-input multiple-output–Orthogonal frequency division multiplexing
- [Show abstract] [Hide abstract] ABSTRACT: Due to the efficiency of mitigation multipath delay spread, orthogonal frequency division multiplexing (OFDM) is extensively used in the wireless local area network (WLAN) domain, such as the IEEE 802.11a standard defined by the IEEE 802.11 standardization group and the HIPERLAN/2 defined by the European Telecommunication Standards Institute Project on Broadband Radio Access Networks. OFDM based WLAN system is very sensitive to the power amplifier distortion and the carrier frequency offset. The performance of the OFDM based WLAN system in the presence of the power amplifier distortion and the carrier frequency offset under practical fading channel is researched and analyzed in this paper. A closed form of bit error rate (BER) is derived for the OFDM based WLAN system in the presence of the power amplifier distortion and the carrier frequency offset under practical fading channel. The effects of the power amplifier distortion and the carrier frequency offset on the OFDM based WLAN system performance are comparatively studied by the theoretical method and by the simulation method under practical multipath fading channels. Studies show that the theoretical and simulated results match well. KeywordsPower amplifier distortion–Carrier frequency offset–Wireless local area network
- [Show abstract] [Hide abstract] ABSTRACT: Cyber Physical Systems (CPS) are the intelligent systems which physical and engineered systems are closely integrated. This paper first introduced the concept of CPS, summarized the status of CPS and analyzed the differences between CPS and popular "The Internet of Things". Followed list the CPS applications of smart grid, water distributed networks and assistive devices, described the efforts that CPS pay for to constructed the wise earth and the far-reaching impacts on society and economy. Finally, this paper dissected the great challenges on the CPS research and looked ahead the prospects of it.
- [Show abstract] [Hide abstract] ABSTRACT: OFDM is extensively used in modern digital television terrestrial broadcasting (DTTB) systems to support high performance bandwidth-efficient multimedia services, such as the Digital Video Broadcasting for Terrestrial Television (DVB-T) proposed as the European DTTB standard and the Digital Television/Terrestrial Multimedia Broadcasting (DTMB) proposed as the Chinese DTTB standard. System based on OFDM is sensitive to the phase error produced due to not only the tuner phase noise but also the phase deviation of residual sampling clock offset, frequency offset estimation error and Doppler spread in the mobile applications. In this paper, a channel equalization with phase error mitigation scheme is proposed for the time domain synchronous OFDM (TDS-OFDM) based Chinese digital television terrestrial broadcasting systems. In the proposed channel equalization scheme, the influence of the phase error on the performance of the TDS-OFDM based Chinese DTTB systems is split into a multiplicative part (which is common to all sub-carriers and is referred to as the common phase rotation (CPR)) and an additive part (which is referred to as the inter-carrier interference (ICI)). Both the CPE and the ICI are estimated and compensated in the proposed scheme. Simulation results for system with phase error and under mobile environment are presented to illustrate the effectiveness of the proposed scheme.
- [Show abstract] [Hide abstract] ABSTRACT: In cellular mobile communications, multipath fading, shadowing, near-far problem and the Doppler effect have led to a complex radio wave propagation environment. Furthermore, with the continuously increasing of users and operations, not only new bandwidth is required, new technologies and measures are also expected to improve the system capacity and channel capacity. This paper introduces the general structure of multi-antenna communication systems firstly, then analyzes the characteristics of various multi-antenna technologies and their advantages over single antenna system when applied in cellular mobile communications. Finally, combined with the trends and requirements of cellular mobile communications, the further application of multi-antenna technologies in future cellular mobile communications is prospected.
- [Show abstract] [Hide abstract] ABSTRACT: To test and validate the characteristics of amplifying circuits, a realized method based on synchronous sampling is introduced in this paper. Based on double sample/holder and synchronous sampling mode of TMS320F2812, it is implemented that several pairs of signals can be sampled and tested synchronously. The method of hardware connection, register and sampling frequency setting is introduced, and how to decrease test error is discussed. In this design scheme, synchronous sampling and test to several pairs of signals can be realized in one time, and no peripheral ADC was needed, so there are several advantages such as lower cost, higher test speed and simple design scheme.
Conference Paper: Energy-aware data gathering protocol for wireless sensor networks[Show abstract] [Hide abstract] ABSTRACT: An energy-aware data gathering protocol called EADGP that maximizes the network lifetime for wireless sensor networks is proposed in this paper. EADGP introduces a novel distributed hierarchical clustering method. In order to reduce energy consumption and realize load balance, a new cost metric and a metric-mapping function is presented during the cluster head selection phase. Unlike traditional energy-based distributed clustering algorithms, the new metric considers not only the residual energy of nodes, but also energy efficiency. The metric-mapping function maps the metric to a backoff duration, the node with a minor cost metric will produce a shorter time to compete as a cluster head. Furthermore, in EADGP, cluster heads use distributed energy balanced routing to forward data to the base station. Thus EADGP can evenly distribute energy dissipation among all nodes. Simulation results show that EADGP significantly improves the energy efficiency and the network lifetime of a wireless sensor network as compared with some existing protocols.
Ningbo UniversityNing-po, Zhejiang Sheng, China
Dalian Maritime University
Lü-ta-shih, Liaoning, China
- College of Information Science and Technology
Beijing, Beijing Shi, China
- Department of Electronic Engineering