tracking 时变移动信道的文章

Eulalia

【文件名】:06614@52RD_acking of Time-varying Mobile Radio Channels I.rar
【格　式】:rar
【大　小】:241K
【简　介】:Abstract—Adaptation algorithms with constant gains are
designed for tracking smoothly time-varying parameters of linear
regression models, in particular channel models occurring in mobile
radio communications. In a companion paper, an application
to channel tracking in the IS-136 TDMA system is discussed. The
proposed algorithms are based on two key concepts. First, the
design is transformed into a Wiener filtering problem. Second,
the parameters are modeled as correlated ARIMA processes with
known dynamics. This leads to a new framework for systematic
and optimal design of simple adaptation laws based on prior information.
The algorithms can be realized asWiener filters, called
Learning Filters, or as “LMS/Newton” updates complemented
by filters that provide predictions or smoothing estimates. The
simplest algorithm, named the Wiener LMS, is presented here.
All parameters are here assumed governed by the same dynamics
and the covariance matrix of the regressors is assumed known.
The computational complexity is of the same order of magnitude
as that of LMS for regressors which are either white or have
autoregressive statistics. The tracking performance is, however,
substantially improved.
【目　录】:
I. INTRODUCTION
II. THE TRACKING PROBLEM
III. WIENER LMS DESIGN
IV. SIMPLIFIED WIENER LMS
V. CONCLUDING REMARKS

Eulalia

【文件名】:06614@52RD_acking of Time-Varying Mobile Radio Channel II(1).rar
【格　式】:rar
【大　小】:214K
【简　介】:Abstract—Low-complexity WLMS adaptation algorithms, of
use for channel estimation, have been derived in a companion
paper. They are here evaluated on the fast fading radio channels
encountered in IS-136 TDMA systems, with the aim of clarifying
several issues: How much can channel estimation performance
be improved with these tools, as compared to LMS adaptation?
When can an improved tracking MSE be expected to result
in a meaningful reduction of the bit error rate? Will optimal
prediction of future channel estimates significantly improve the
equalization? Can one single tracker with fixed gain be used for
all encountered Doppler frequencies and SNR’s, or must a more
elaborate scheme be adopted? These questions are here investigated
both analytically and by simulation. An exact analytical
expression for the tracking MSE on two-tap FIR channels is
presented and utilized. With this tool, the MSE performance and
robustness of WLMS algorithms based on different statistical
models can be investigated. A simulation study then compares
the uncoded bit error rate of detectors, where channel trackers
are used in decision directed mode in conjunction with Viterbi
algorithms. A Viterbi detector combined with WLMS, based on
second order autoregressive fading models possibly combined
with integration, provides good performance and robustness at a
reasonable complexity.
【目　录】:
I. INTRODUCTION
II. THE CHANNEL MODEL
III. THE CHANNEL ESTIMATOR
IV. DYNAMIC FADING MODELS
V. PERFORMANCE ANALYSIS
VI. MSE PERFORMANCE
VII. SIMULATION STUDY
VIII. CONCLUSIONS