This study introduces a new low complexity Max-Log-map based channel estimation technique operating in a multi-path band limited channel. The proposed estimation technique is based on an iterative procedure derived th...
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This study introduces a new low complexity Max-Log-map based channel estimation technique operating in a multi-path band limited channel. The proposed estimation technique is based on an iterative procedure derived through the maximum a posteriori probability approach. Wireless communication channels often undergo frequency selective fading that leads to inter-symbol interference, which limits the performance of wireless indoor systems. Performance of the algorithms is assessed by combined analysis and simulation. Results are presented and compared against the performance of conventional Log-map algorithm. The obtained results show that the required bit-error-rate performance can be achieved with a lower number of iterations using the proposed low complexity algorithm compared to using the conventional Log-map algorithm.
Turbo coding is a powerful coding technique that can provide highly reliable data transmission at extremely low signal-to-noise ratios. Owing to the computational complexity of the employed decoding algorithm, the rea...
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Turbo coding is a powerful coding technique that can provide highly reliable data transmission at extremely low signal-to-noise ratios. Owing to the computational complexity of the employed decoding algorithm, the realization of turbo decoders usually takes a large amount of memory space and potentially long decoding delay. Therefore, an efficient memory management strategy becomes one of the key factors toward successfully implementing turbo decoders. This paper focuses on the development of general structures for efficient memory management of turbo decoders employing the sliding-window (Log-)map algorithm. Three different structures and the associated mathematic representations are derived to evaluate the required memory size, average decoding rate, and latency based on the speed and the number of the adopted processors. Comparative results show the dependency of the resulting performance based on a set of parameters;thus provide useful and general information on practical implementations of turbo decoders.
The effects of the channel reliability factor on the performance of turbo decoders that use a maximum a posteriori probability algorithm are investigated for wireless communication fading channels, such as Bluetooth s...
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The effects of the channel reliability factor on the performance of turbo decoders that use a maximum a posteriori probability algorithm are investigated for wireless communication fading channels, such as Bluetooth systems. The channel reliability factor is related to the channel signal-to-noise ratio. For various values of the channel reliability factor, the obtained performance curves of the maximum a posteriori probability algorithm are given for the case of DMx Bluetooth data packets. When the channel reliability factor increases, the bit-error-rate performance of the DMx Bluetooth data packets also increases over fading channels.
作者：
Lee, IYKorea Univ
Dept Radio Commun Engn Seoul 136701 South Korea
It is usually assumed that all state metric values are necessary in the maximum a posteriori (map) algorithm in order to compute the a posteriori probability (APP) values. This paper extends the mathematical derivatio...
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It is usually assumed that all state metric values are necessary in the maximum a posteriori (map) algorithm in order to compute the a posteriori probability (APP) values. This paper extends the mathematical derivation of the original map algorithm and shows that the log likelihood values can be computed using only partial state metric values. By processing N stages in a trellis concurrently, the proposed algorithm results in savings in the required memory size and leads to a power efficient implementation of the map algorithm in channel decoding. The computational complexity analysis for the proposed algorithm is presented. Especially for the N = 2 case, we show that the proposed algorithm halves the memory requirement without increasing the compuational complexity.
A novel image segmentation algorithm based on a Bayesian framework is studied in this paper. We presents a new region and statistics based approach, which combines Voronoi tessellation technique and Maximum a posterio...
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ISBN:
(纸本)9781467365932
A novel image segmentation algorithm based on a Bayesian framework is studied in this paper. We presents a new region and statistics based approach, which combines Voronoi tessellation technique and Maximum a posterior / Maximi-zation of the posterior marginal (map / MPM) algorithm. The image domain is partitioned into a group of sub-regions by Voronoi tessellation, each of which is a component of homogeneous regions. And the image is modeled on the supposition that the intensities of pixels in each homogenous region satisfy an identical and independent gamma distribution. The initial segmentation is applied to obtain number of the initial motions and the corresponding initial parameters of the image model. Then the parameters are updated by using the given parameter estimation method. A fast estimation procedure for the posterior marginals is added to the map algorithm. The experiment results show that the proposed algorithm here is effective.
This paper proposes an approximate calculation for correction function of Log-map algorithm and obtains a well turbo decoding in AWGN channel. The algorithm mainly uses the method of segmenting and fitting for correct...
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ISBN:
(纸本)9781424458479
This paper proposes an approximate calculation for correction function of Log-map algorithm and obtains a well turbo decoding in AWGN channel. The algorithm mainly uses the method of segmenting and fitting for correction function by spline function. The proposed method has solved the difficulties and obstacles resulting from inaccessible calculation of correction function with exponential and logarithm computations. It shows that error correction performance of turbo decoder with the interpolation function to calculate the correction function is the same as that with Log-map algorithm and the former algorithm complexity is much obviously lower than the latter.
It is usually assumed that for implementing the maximum a posteriori (map) decoding algorithm, saving all the state metrics is required. This memory requirement makes the map an impractical decoding algorithm especial...
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ISBN:
(纸本)9781612849935
It is usually assumed that for implementing the maximum a posteriori (map) decoding algorithm, saving all the state metrics is required. This memory requirement makes the map an impractical decoding algorithm especially for the non-binary block codes. In this paper, we present a modification of the map algorithm, in order to make it a more feasible algorithm. The computational complexity analysis and the memory requirements as well as the simulation results for the proposed algorithm are presented.
This paper proposes an approximate calculation for correction function of Log-map algorithm and obtains a well turbo decoding in AWGN channel. The algorithm mainly uses the method of segmenting and fitting for correct...
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This paper proposes an approximate calculation for correction function of Log-map algorithm and obtains a well turbo decoding in AWGN channel. The algorithm mainly uses the method of segmenting and fitting for correction function by spline function. The proposed method has solved the difficulties and obstacles resulting from inaccessible calculation of correction function with exponential and logarithm computations. It shows that error correction performance of turbo decoder with the interpolation function to calculate the correction function is the same as that with Log-map algorithm and the former algorithm complexity is much obviously lower than the latter.
In this letter, a new method for decoding turbo-like codes is proposed to simplify the hardware implementation of Log-map algorithm. In our method, the multivariable Jacobian logarithm in Log-map algorithm is actually...
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In this letter, a new method for decoding turbo-like codes is proposed to simplify the hardware implementation of Log-map algorithm. In our method, the multivariable Jacobian logarithm in Log-map algorithm is actually concatenated by recursive 1D Jacobian logarithm units. Two new approximations of Log-map algorithm based on these 1D units are then presented, which have good approximated accuracy and is simple for hardware implementation. We further suggest a novel decoding scheme that its complexity is near the Max-Log-map while the performance is close to the Log-map algorithm.
Turbo code is a powerful forth error-correct coding technology, it can obtain high reliability data transmitting under low SNR circumstance. Turbo code is one of the key technologies of the 3(rd) generation mobile com...
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Turbo code is a powerful forth error-correct coding technology, it can obtain high reliability data transmitting under low SNR circumstance. Turbo code is one of the key technologies of the 3(rd) generation mobile communication system. In the application of Turbo code, its decoding algorithm became the most valuable question for discussion. In this paper, we based on the application of Turbo code in 3(rd) generation mobile communication system, analysis Log-map algorithm, and implemented Sliding-Window technology into Turbo decoding. Improved Log-map algorithm kept decoding performance unchanged, reduced complexity of the algorithm, decreased the consumption of memory and shortened the time of decoding, more fit for application.
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