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Articles by Guanghui Ren
Total Records ( 12 ) for Guanghui Ren
  Guanghui Ren , Zhilu Wu , Nan Zhao and Maoliu Lin
  Multiuser detection, which can efficiently mitigate the multiple access interference, is a hot topic nowadays for CDMA systems. In this research, a mutated ant colony optimization (MACO) algorithm is proposed by introducing the mutation mechanism to the ACO algorithm and is applied to multiuser detection. Compared with the ACO multiuser detector, the presented MACO multiuser detector can lead to quicker convergence and avoid local optima with almost the same computational complexity. Via computer simulations in CDMA communication system, it is shown that the performance of MACO multiuser detector in reducing the near-far effect and bit-error rate is much better than that of ACO multiuser detector and is also close to or even equal to the performance of optimal multiuser detector.
  Zhilu Wu , Nan Zhao , Shuying Li and Guanghui Ren
  In this research, a Baseband Quadrature Complex Rotation Multi-Symbol Detection (BQCR-MSD) algorithm is proposed. It can greatly reduce the computational complexity of MSD due to the partial correlation and complex rotation techniques applied, so is more suitable for implementation on large scale digital device such as Field Programmable Gate Array (FPGA). Simulation results also show that despite of the computational complexity decrease, the performance of BQCR-MSD algorithm is excellent and very close to that of MSD.
  Jinglong Wu , Guanghui Ren and Peng Li
  In this study, we investigate to improve search speed and meanwhile guarantee robustness by a new method including 3 stages. Especially, in these stages, there is a kind of coarse retrieval method whereby the elements of features are tested to exclude mismatched points of a long audio signal at very high speed. Some tests have been implemented to compare with other methods with good performance. Experimental results demonstrate that the new method offers quicker retrieval speed and guarantees the robustness in additive noise environment.
  Zhilu Wu , Qiyang Wang , Nan Zhao and Guanghui Ren
  In this study, a novel bit synchronization method for the telemetry digital Intermediate Frequency (IF) receiver of PCM/FM signals at low Signal-Noise Ratios (SNR) is proposed. Bit synchronization is also known as symbol synchronization, which is an important technique in the communication systems nowadays and it is essential in both baseband transmission and radio-frequency transmission systems. An imperfect bit synchronization algorithm will affect the performance of the communication system and even cause the communication system work abnormally. As SNR in PCM/FM telemetry system is much lower than other conventional communication systems, traditional bit synchronization algorithms can’t meet the requirements. So by means of the mean filtering technique in image processing, a novel bit synchronization algorithm at low SNR for PCM/FM based on FPGA is proposed and has already been implemented in our telemetry digital IF receiver. Via simulations, it is shown that this algorithm can achieve excellent performance at low SNR.
  Guanghui Ren , Xiaokai Hu , Gangyi Wang and Jinglong Wu
  JPEG XR is a new image coding standard that achieves high compression performance and low complexity. In this study, we propose a novel architecture of Lapped Biorthogonal Transform (LBT) for JPEG XR encoding using an optimized Quadriphase-RAM (QRAM) and a fully pipelined LBT module. In the previous architectures, the whole image data are stored in the main memory so that the waste of memory and the delay for the whole image acquisition must be inevitable. The proposed QRAM minimizes the memory size and improves the speed of image processing and the fully pipelined LBT module achieves higher throughput than that of the previous architectures. Results show the proposed architecture which achieves 121.2 M pixel/sec at 125 MHz can be used for the real-time JPEG XR encoding.
  Guanghui Ren , Peng Li and Gangyi Wang
  The gray-scale projection algorithm can detect the motion vector of continuous frames rapidly in digital image stabilization system, but the interference of local moving objects may influence the estimation accuracy. In this study, we present a novel coarse-to-fine image stabilization approach which combined gray-scale projection algorithm with block matching algorithm by analyzing two classical motion estimation algorithms. The proposed method considers both accuracy and efficiency, since it makes good use of low computational complexity of gray-scale projection algorithm and high accuracy of block matching algorithm. The experimental simulations reveal that, expect for its low computational complexity, the proposed algorithm achieves high motion estimation accuracy. Moreover, it can efficiently avoid the interference caused by local moving objects.
  Jun Deng , Guanghui Ren , Yansheng Jin and Wenjing Ning
  Finding sparse solution to undetermined linear systems is one of the fundamental challenging issues in compressive sensing problems and other signal processing applications. This study has presented a novel iterative weighted gradient projection algorithm, referred to as the IWGP, to recover sparse signal in large-scale settings. IWGP is based on a widely used weighted filter technique in signal processing which reduces undesirable influence so that gradient projection can be applied to achieve computational efficiency. Numerical experiments are carried out and the results demonstrate the proposed algorithm is significantly faster than the fastest known methods for the l1 minimization programs and further show that the computational time isn’t sensitive to the sparsity level of original signal.
  Lihui Jiang , Guanghui Ren , Gangyi Wang , Zhilu Wu and Shaobin Li
  The acquisition of Pseudo-Noise (PN) code is one of the essential technologies in Direct Sequence Spread Spectrum (DS/SS) communication. Conventional Parallel Matched Filter (CPMF) features in high acquisition speed but it will consume a large amount of hardware resource in the case of long PN code. This paper focuses on reducing the hardware consumption and proposes a novel matched filter architecture: Time Division Multiplex Matched Filter (TDMMF). With identical processing gain as CPMF, TDMMF can save the hardware consumption by 50, 75% and even more through reusing the shift registers, multipliers and accumulators. This makes the proposed TDMMF suitable for high speed acquisition of long PN code.
  Guanghui Ren , Shengyang He and Yunlong Yang
  In order to solve the limitation of data rate caused by long rise and fall time of light emitting diodes, m-ary return-to-zero optical pulse amplitude modulation is proposed in this paper for improving the bandwidth efficiency of indoor visible light communication. M-ary return-to-zero optical pulse amplitude modulation transmits information through a subtle change of illumination intensity and supports both flicker mitigation and dimming control functions. An indoor communication link establishing process is introduced as a parameter training method based on the principle of successive approximation. Theoretical analysis shows that, m-ary return-to-zero optical pulse amplitude modulation can be used to achieve higher bandwidth efficiency without sacrificing the symbol error rate and bit error rate performance of an indoor visible light communication system. When the ratio of a_slot-a_BS is 0.1, then m-ary return-to-zero optical pulse amplitude modulation can provide 1.47 times bandwidth efficiency than that of on-off keying, 3.5 times than that of digital pulse interval modulation and 5.9 times than that of pulse position modulation. M-ary return-to-zero optical pulse amplitude modulation can be used as a candidate bandwidth efficiency modulation scheme to improving data rate of an indoor visible light communication system.
  Gangyi Wang , Guanghui Ren , Lihui Jiang and Taifan Quan
  Great progress has been made in image dehazing recently, while the sky region processed by these algorithms tends to be degraded by serious noise and color distortion. Based on the in-depth analysis on the degradation, the paper proposes an improved dehazing algorithm which first segments the haze image into the sky and non-sky region, then estimates the coefficients of the two regions separately, followed by the combination of the regions with a refining step. Experiment results show that the proposed algorithm provides significant advantage in generating smoother and more natural sky region, while keeping the non-sky region almost the same as the state of the art algorithms.
  Shengyang He , Guanghui Ren , Haoran Zhu , Yunlong Yang and Longwen Wu
  A modified integrated circuit interface based on M-ary digital pulse cycle modulation is proposed in this study by describing its principle and structure to reduce the complexity of a high-speed circuit design and to improve the data transfer rate of a bandwidth-limited system. A demonstration system is built by using Field Programmable Gate Array (FPGA) to simulate the transceiver functions in a bandwidth-limited RS232 bus with a maximum data transfer rate is 320 Kbps and the interface proposed is used to achieve the maximum data transfer rate of more than 1.1 Mbps, without any other change in hardware circuit. Experimental results indicate that the interface proposed can be used to achieve a better data transfer performance.
  Guanghui Ren , Shengyang He and Yunlong Yang
  An improved recursive channel model based on Barry’s is proposed by introducing the wiring topology of light source for indoor visible light communication systems, including the path of communication access point to LED array access point and LED array access point to LED. Theoretical analysis and simulation results indicate that, the improved model presented in this paper can be used to better analyze the ISI phenomenon of an indoor visible light communication system. And mitigation strategies based on the formula of an improved channel model are proposed for ISI which provides a valuable reference for the actual application of a VLC system.
 
 
 
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