-
[show abstract]
[hide abstract]
ABSTRACT: This paper introduces a hybrid forward-error correction/automatic
repeat-request (ARQ) system that employs rate compatible punctured turbo
(RCPT) codes to achieve enhanced throughput performance over a
nonstationary Gaussian channel. The proposed RCPT-ARQ system combines
the performance of turbo codes with the frugal use of incremental
redundancy inherent in the rate compatible punctured convolutional codes
of Hagenauer (1988). Moreover, this paper introduces the notion of
puncturing the systematic code symbols of a turbo code to maximize
throughput at signal-to-noise ratios (SNRs) of interest. The resulting
system provides both an efficient family of achievable code rates at
middle to high SNR and powerful low-rate error correction capability at
low SNR
IEEE Transactions on Communications 07/2000; · 1.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: For pt.I see ibid., vol.47, p.1570-92 (1999). In Rowitch and
Milstein (1999), a convolutionally encoded multicarrier asynchronous
direct-sequence code-division multiple-access (DS-CDMA) system was
proposed and compared to a classical single-carrier DS-CDMA system
employing a RAKE receiver and the same convolutional code, in the
presence of additive white Gaussian noise and multiple-access
interference. This paper considers the additional impact of various
forms of narrow-band interference on the performance of these two
systems and the ability of the multicarrier system to effectively
suppress the interference using the innate structure of its receiver. At
roughly equivalent receiver complexity, results demonstrate superior
performance of the multicarrier system in the presence of such
interference, without requiring the addition of a front-end interference
suppression filter
IEEE Transactions on Communications 12/1999; · 1.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents a multicarrier asynchronous direct-sequence
code-division multiple-access (DS-CDMA) system wherein the output of a
convolutional encoder modulates multiple band-limited DS-CDMA waveforms,
which are transmitted in parallel at different carrier frequencies. The
receiver detects and combines signals for the desired user and feeds a
soft-decision Viterbi decoder. The performance of this system is
compared to that of a conventional single-carrier DS-CDMA system with a
RAKE receiver, assuming a slowly varying frequency-selective Rayleigh
fading channel and assuming the presence of additive white Gaussian
noise and multiple-access interference. Results will demonstrate similar
performance at roughly equal receiver complexity
IEEE Transactions on Communications 11/1999; · 1.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents a multicarrier asynchronous direct sequence
(DS) code division multiple access (CDMA) system, wherein the output of
a convolutional encoder modulates multiple bandlimited DS-CDMA waveforms
which are transmitted in parallel at different carrier frequencies. The
receiver detects and combines signals for the desired user and feeds a
soft decision Viterbi decoder. The performance of this system is
compared to that of a conventional single carrier DS-CDMA system with a
RAKE receiver, assuming a slowly varying, frequency selective, Rayleigh
fading channel and assuming the presence of AWGN, multiple access
interference, and partial-band interference. Results will demonstrate
similar performance at roughly equal receiver complexity in the absence
of partial-band interference, and superior performance of the
multicarrier system in the presence of partial-band interference
Military Communications Conference, 1996. MILCOM '96, Conference Proceedings, IEEE; 11/1996
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents a multicarrier asynchronous direct sequence
(DS) code division multiple access (CDMA) system which, through the use
of linear convolutional codes, achieves frequency diversity of an order
above and beyond that realized by path diversity in a conventional RAKE
DS-CDMA system. A frequency selective Rayleigh fading channel is
decomposed into M frequency non-selective channels, based on the channel
coherence bandwidth. Then, a rate 1/M convolutional code is used to
modulate the M DS-CDMA waveforms. Diversity gains on the order of the
code free distance may now be achieved. This system exhibits robust
performance in the presence of narrowband interference and jamming, yet
preserves the natural multiple access interference rejection properties
inherent in the standard DS-CDMA model. Significant capacity gains over
the single carrier system are demonstrated, while holding overall system
bandwidth and information rates constant
Military Communications Conference, 1995. MILCOM '95, Conference Record, IEEE; 12/1995
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents a multicarrier signaling technique for an
asynchronous direct sequence (DS) code division multiple access (CDMA)
system which employs linear convolutional codes to achieve performance
gains in excess of path diversity gains realized in conventional single
carrier RAKE DS CDMA systems
Information Theory, 1995. Proceedings., 1995 IEEE International Symposium on; 10/1995
