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ABSTRACT: A robust error control scheme for data transmission in CDMA-based
cellular systems is proposed which employs outer Reed-Solomon codes
concatenated with inner convolutional codes. The performance of this
scheme is analyzed assuming nonperiodic random spreading sequences and a
Rake receiver with perfect knowledge of the channel. In particular, a
simple model for the memoryless inner coding channel that encompasses
the effects of multiple access interference, self-noise and thermal
noise is first derived. Using new tight upper bounds on bit- and
symbol-error probabilities of convolutional codes over Nakagami,
Rayleigh, and Rician fading multipath channels, the performance of the
concatenated coding scheme is then evaluated. The
Reed-Solomon/convolutional coding scheme has been adopted by the
European RACE Project Code Division Testbed (CODIT) and implemented in
an experimental testbed. The code design methodology, which has been
used to specify the 9.6-, 64-, and 128-kbit/s data traffic channels of
the CODIT testbed, is presented and the single-cell CDMA capacity is
computed
IEEE Transactions on Communications 11/1997; · 1.68 Impact Factor
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ABSTRACT: The performance of convolutionally coded DS-CDMA systems is
analyzed assuming nonperiodic random spreading sequences, ideal
interleaving and a RAKE receiver with perfect knowledge of the channel.
In particular, a simple model for the memoryless coding channel that
encompasses the effects of multiple access interference, self-noise and
thermal noise is first derived. This coding channel model illustrates
clearly how ideal channel state information is used at the receiver.
Using new tight upper bounds on the bit error probability of
convolutional codes over Nakagami, Rayleigh, and Rice fading multipath
channels, the performance of convolutionally coded coherent DS-CDMA
systems is then evaluated. Finally, the single-cell CDMA capacity is
computed and the tradeoffs between performance and maximum number of
simultaneous users in a cell are studied
Global Telecommunications Conference, 1996. GLOBECOM '96. 'Communications: The Key to Global Prosperity; 12/1996
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ABSTRACT: For an aperiodic invertible sequence of length L, the optimality
criterion is chosen to be the minimum noise enhancement factor of the
corresponding aperiodic inverse filter. The noise enhancement factor is
defined as the ratio of the noise energies at the outputs of the
aperiodic inverse and the normalized matched filters of the sequence due
to white noise at the filter inputs. Optimal binary sequences of length
L⩽32 and optimal binary skew symmetric sequences of length
33⩽L⩽59 were found by exhaustive search. The search for
near-optimal sequences is shown to have strong connections to the search
for sequences with large products of Golay (1977) merit factor times the
minimum of the energy density spectrum. Based on Legendre sequences and
on Kronecker product sequences, long near-optimal binary sequences are
found that have associated noise enhancement factors close to 1 dB
IEEE Transactions on Information Theory 10/1996; · 3.01 Impact Factor
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ABSTRACT: It is shown that the sum capacity of the symbol-synchronous
code-division multiple-access channel with equal average-input-energy
constraints is maximized precisely by those spreading sequence multisets
that meet Welch's lower bound on total squared correlation. It is
further shown that the symmetric capacity of the channel determined by
these same sequence multisets is equal to the sum capacity
IEEE Transactions on Information Theory 08/1994; · 3.01 Impact Factor
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ABSTRACT: This paper presents exhaustive search results of binary sequences
of length L⩽32 that provide small noise enhancement factors when
filtered with their aperiodic inverse filters and describes two
construction methods for longer such sequences
Information Theory, 1994. Proceedings., 1994 IEEE International Symposium on; 08/1994
