For binary codes, Fossorier et al. (1998), have shown that the soft-output Viterbi algorithm (SOVA) becomes equivalent to the max-log-maximum a posteriori (map) algorithm after a modification. In this letter, such mod...
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A novel video motion object automatic segmentation algorithm based on a Bayesian framework is studied in this paper. A fast estimation procedure for the posterior marginals is added to the map algorithm. The field is ...
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ISBN:
(纸本)9781424438822
A novel video motion object automatic segmentation algorithm based on a Bayesian framework is studied in this paper. A fast estimation procedure for the posterior marginals is added to the map algorithm. The field is initialized as the temporal segmentation result and the spatial segmentation is provided as an observed field of the image. Firstly,initial segmentation is applied to obtain number of the initial motions and the corresponding initial parameters of the motion model. Then the parameters are updated by using the given parameter estimation method. The experiment results show that the algorithm proposed is effective.
In this paper, we integrate inertial navigation system (INS) with wireless sensor network (WSN) to enhance the accuracy of indoor localization. Inertial measurement unit (IMU), the core of the INS, measures the accele...
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In this paper, we integrate inertial navigation system (INS) with wireless sensor network (WSN) to enhance the accuracy of indoor localization. Inertial measurement unit (IMU), the core of the INS, measures the accelerated and angular rotated speed of moving objects. Meanwhile, the ranges from the object to beacons, which are sensor nodes with known coordinates, are collected by time of arrival (ToA) approach. These messages are simultaneously collected and transmitted to the terminal. At the terminal, we set up the state transition models and observation models. According to them, several recursive Bayesian algorithms are applied to producing position estimations. As shown in the experiments, all of three algorithms do not require constant moving speed and perform better than standalone ToA system or standalone IMU system. And within them, two algorithms can be applied for the tracking on any path which is not restricted by the requirement that the trajectory between the positions at two consecutive time steps is a straight line.
A new type of recursive algorithm for decoding turbo codes is proposed, based on a symbol-by-symbol maximum a posteriori probability algorithm. It requires only a forward recursion and has lower computational complexi...
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A new type of recursive algorithm for decoding turbo codes is proposed, based on a symbol-by-symbol maximum a posteriori probability algorithm. It requires only a forward recursion and has lower computational complexity. The number of variables to be stored increases linearly with the decoding delay. For iterative decoding, the extrinsic information given by the new algorithm is also described. This algorithm can be used in continuous decoding for both recursive and non-recursive encoder.
The most difficult design issue for turbo codes, which is the most recent and successful channel coding method to approach the channel capacity limit, is the design of the iterative decoders which perform calculations...
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The most difficult design issue for turbo codes, which is the most recent and successful channel coding method to approach the channel capacity limit, is the design of the iterative decoders which perform calculations for all possible states of the encoders. BCJR (map) algorithm, which is used for turbo decoders, embodies complex mathematical operations such as division, exponential and logarithm calculations. Therefore, BCJR algorithm was avoided and the sub-optimal derivatives of this algorithm such as Log-map and Max-Log-map were preferred for turbo decoder implementations. BCJR algorithm was reformulated and wrapped into a suitable structure for FPGA implementations at previous works [1]. Reformulated BCJR algorithm is implemented in this work. Complex mathematical operations which run slowly on hardware (division, exponential and logarithm calculations) are read from look-up-tables and high performance calculation structures are established. Implemented system is verified through simulations. It is observed that the BER performance obtained is better than the Log-map algorithm as expected.
Separate coding can achieve better characteristics than Reed-Solomon code in a binary vanishing channel when combined with convolutional code. Separate coding has the advantage that decoding is easy, since partial cod...
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Separate coding can achieve better characteristics than Reed-Solomon code in a binary vanishing channel when combined with convolutional code. Separate coding has the advantage that decoding is easy, since partial codes are decoded independently. In past decoding methods, however, decoded information other than the partial encoder under consideration is not utilized. When separate coding is applied to a PPM channel, the output of the partial encoder in question is completely correlated with the outputs of the other encoders. Thus, it should be possible to improve the error rate of the whole system by effectively utilizing the decoded information from other decoders. The purpose of this paper is to utilize the correlation between the outputs of the partial encoder in separate coding, and to propose an iterative decoding method based on the decoded information of multiple partial encoders. The improvement in the error rate, the comparative decoding complexity, and the external information to be used in iterative decoding are investigated. Computer simulations show that characteristics close to those of maximum likelihood decoding up to approximately 0.5 dB are achieved by the proposed decoding method while limiting the increase in decoding complexity due to the increase in the number of encoders. (C) 2003 Wiley Periodicals, Inc.
This paper introduces the characteristics of wireless channel fading, and uses the model of Rayleigh fading channel to simulate the sea wireless channel. Using Turbo codes as the encoding and decoding scheme of sea wi...
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This paper introduces the characteristics of wireless channel fading, and uses the model of Rayleigh fading channel to simulate the sea wireless channel. Using Turbo codes as the encoding and decoding scheme of sea wireless communication system. Introducing two kinds of encoding algorithm of Turbo codes, and put forward the method of re-encoding aiming to improve the performance of map decoding of Turbo codes. The re-encoding algorithm of Turbo codes will be applied to the channel codec of sea wireless communication system. Finally, we implement the new turbo encoding and decoding algorithms on DSP. Simulation shows that re-encoding method can significantly improve the map decoding performance.
A new FFT-based trellis receiver for multicarrier signals with nonorthogonal frequency spacing (spectrally efficient frequency division multiplexing, SEFDM) is proposed. It is based on FFT and max-log-map algorithm, w...
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ISBN:
(纸本)9781509013296
A new FFT-based trellis receiver for multicarrier signals with nonorthogonal frequency spacing (spectrally efficient frequency division multiplexing, SEFDM) is proposed. It is based on FFT and max-log-map algorithm, which is adapted to work with frequency samples of received signal. The iterative version of demodulator is also developed. The performance of proposed iterative QPSK-SEFDM demodulation is comparable with the one of classic coded QPSK modulation while the spectral efficiency remains very high. The proposed algorithms can demodulate SEFDM signals with large number of subcarriers.
In this paper, a new state metric normalization technique is proposed for maximum-a-posteriori-probability (map) algorithm to enhance the throughput of map decoder. Biterror-rate (BER) performance comparison showed th...
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ISBN:
(纸本)9781467361262
In this paper, a new state metric normalization technique is proposed for maximum-a-posteriori-probability (map) algorithm to enhance the throughput of map decoder. Biterror-rate (BER) performance comparison showed that the map algorithm based on the proposed normalization technique has a coding gain of 0.25 dB at a BER of 10~(-4) in comparison with map algorithm based on the subtractive normalization technique. An architecture for map decoder based on the new normalization technique has been proposed with a reduced critical path delay as compared to the contributions in literature. Subsequently, a field-programmable-gate-array (FPGA) implementation of the new map decoder is carried out. Thereby, the proposed decoder based on non-parallel radix-2 and radix-4 architectures are able to achieve high throughputs of 514 Mbps and 1.028 Gbps respectively.
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