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Channel Estimation Strategies for Coded MIMO Systems
, 2004
"... High transmission data rate, spectral efficiency, and reliability are necessary for future wireless communications systems. In a multipathrich wireless channel, deploying multiple antennas at both the transmitter and receiver achieves high data rate, without increasing the total transmission power ..."
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High transmission data rate, spectral efficiency, and reliability are necessary for future wireless communications systems. In a multipathrich wireless channel, deploying multiple antennas at both the transmitter and receiver achieves high data rate, without increasing the total transmission power or bandwidth. When perfect knowledge of the wireless channel conditions is available at the receiver, the capacity has been shown to grow linearly with the number of antennas. However, the channel conditions must be estimated since perfect channel knowledge is never known a priori. In practice, the channel estimation procedure can be aided by transmitting pilot symbols that are known at the receiver. System performance depends on the quality of channel estimate, and the number of pilot symbols. It is desirable to limit the number of transmitted pilot symbols because pilot symbols reduce spectral efficiency. This thesis analyzes the system performance of coded multipleinput multipleoutput (MIMO) systems for the quasistatic fading channel. The assumption that perfect channel knowledge is available at the receiver must be removed, in order to more accurately
Computation of the active distances for trellis coded modulation
 in Proceedings 5th International ITG Conference on Source and Channel Coding
, 2004
"... Recently, the concept of active distances, originally introduced for binary convolutional codes, was extended to the case of nonlinear trellis coded modulation. These distance measures allow an improved evaluation of the error correcting capability for trellis codes. Typically, the larger the slope ..."
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Recently, the concept of active distances, originally introduced for binary convolutional codes, was extended to the case of nonlinear trellis coded modulation. These distance measures allow an improved evaluation of the error correcting capability for trellis codes. Typically, the larger the slope of the active distances the better the performance of the trellis code for low . Moreover, these distance measures are of particular interest for the design of concatenated coding schemes, with respect to the choice of the inner trellis code as well as the interleaver. In this paper we present a matrix based method to compute the active distances for trellis codes in Euclidean space, encoded by an state finite state machine. The computation is based on a simplified version of the distance generating matrix, which is well known from the calculation of the distance spectrum of trellis codes. In general the distance generating matrix is of size
. We show that for trellis codes, encoded by an state FSM, the distance generating matrix can always be reduced to fiffflffi !"ff. Finally, simulation results are presented that confirm the importance of the active distances. 1
On the Slope of the Active Distances for Trellis Coded Modulation
"... Abstract — The slope is the asymptotic growth rate of the active distances which are of particular interest for the design of trellis coded modulation schemes and concatenated codes. The higher the slope (growth rate) of the active burst distance, the better the error correcting capability of the co ..."
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Abstract — The slope is the asymptotic growth rate of the active distances which are of particular interest for the design of trellis coded modulation schemes and concatenated codes. The higher the slope (growth rate) of the active burst distance, the better the error correcting capability of the code. In this paper we introduce the slope as a new parameter for trellis coded modulation and present a matrix based method for its computation. The example of a trellis code based on asymmetric 4ASK will be used to illustrate the computation and the optimization of the slope. Simulation results confirm the improved error correcting capability for trellis codes with high slope. I.
On Distance Measurement Methods for Turbo Codes
, 2005
"... New digital communication applications, such as multimedia, require very powerful error correcting codes that deliver low error rates while operating at low to moderate signaltonoise ratios (SNRs). Turbo codes have reasonable complexity and can achieve very low error rates if a proper interleaver ..."
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New digital communication applications, such as multimedia, require very powerful error correcting codes that deliver low error rates while operating at low to moderate signaltonoise ratios (SNRs). Turbo codes have reasonable complexity and can achieve very low error rates if a proper interleaver design is in place. The use of welldesigned interleavers result in very low error rates, especially for medium to long interleavers where turbo codes offer the greatest potential for achieving high minimum distance (dmin) values. The reliable determination of a code’s error performance at very low error rates using simulations may take months or may not be practical at all. However, the knowledge of dmin and its multiplicities can be used to estimate the error rates at high SNR. This thesis is concerned with efficient and accurate distance measurement methods for turbo codes. Since high values of dmin can be caused by high input weight values, say up to 20 or higher, if a brute force algorithm is used the accurate determination of dmin requires that all possible input sequences of input weight up to 20 be tested. Testing all possible input
Distance Spectrum Calculation of Symbol Punctured Trellis Coded Modulation
"... Abstract — A special kind of symbolwise puncturing is applied to the code symbols of a constituent trellis coded modulation (TCM) within two very bandwidthefficient concatenated coding schemes namely staggered TCM and parallel concatenated TCM. There exist methods to determine the minimum squared ..."
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Abstract — A special kind of symbolwise puncturing is applied to the code symbols of a constituent trellis coded modulation (TCM) within two very bandwidthefficient concatenated coding schemes namely staggered TCM and parallel concatenated TCM. There exist methods to determine the minimum squared Euclidean distance of TCM for this special puncturing but they are only applicable to a limited number of TCM encoders with certain restrictions in code design. In this work, we present a general approach to calculate the distance spectrum of arbitrary TCM with symbolwise puncturing. Thus, a deeper analysis of the error correcting capability of the underlying code is possible. I.
Extended Transfer Bound Error Analysis for Parametric Channel with Continuous Valued Correlated Random Nuisance Parameter
"... Abstract. In this paper we address the extended use of transfer bound analysis of bit error rate (BER) properties. In conjunction with proper parameter modeling, we offer a method to resolve the problem of transfer bound applicability on a system with random and possibly correlated continuous valued ..."
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Abstract. In this paper we address the extended use of transfer bound analysis of bit error rate (BER) properties. In conjunction with proper parameter modeling, we offer a method to resolve the problem of transfer bound applicability on a system with random and possibly correlated continuous valued nuisance parameters. We introduce a new additional parameter space into the original error space and join them in a product matrix for an extended transfer function evaluation. Example applications with simple trellis code for Rayleigh fading channel and phase synchronization error are investigated to demonstrate the functionality of the proved principle. Computer simulation results are presented for two different codes and various fading scenarios, and comparisons are made among analytical and measured system error performances.