Space-frequency turbo coded OFDM
25 Nov 2001-Vol. 2, pp 876-880
TL;DR: Owing to its maximum transmit diversity gain and large coding gain, space-frequency turbo coded modulation is demonstrated to perform within 2.5 dB of the 10% outage capacity for the variety of practical wideband MIMO radio channels, strongly out performing other space- frequencies coding schemes proposed in literature.
Abstract: A new bandwidth and power efficient signaling scheme is proposed that achieves high data rates over wideband radio channels exploiting the bandwidth efficient OFDM modulation, multiple transmit and receive antennas and large frequency selectivity offered in typical low mobility indoor environments. Owing to its maximum transmit diversity gain and large coding gain, space-frequency turbo coded modulation is demonstrated to perform within 2.5 dB of the 10% outage capacity for the variety of practical wideband MIMO radio channels, strongly out performing other space-frequency coding schemes proposed in literature. A simple way of combining space-frequency coding with OFDM delay diversity for cost effective further increase in bandwidth efficiency by exploiting more than two transmit antennas is also proposed.
Citations
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17 Mar 2002
TL;DR: Performance bounds and simulation results show that the bit-interleaved space-time coded OFDM system can effectively exploit both space and frequency diversity to improve performance.
Abstract: A bit-interleaved space-time coded OFDM system is considered in this paper for frequency-selective fading channels. As OFDM divides a frequency-selective fading channel into a set of parallel flat fading channels, space-time block codes for flat fading are transmitted from each subcarrier by multiple transmit antennas to guarantee space diversity, and code bits are bit-wise interleaved across the subcarriers before being grouped and mapped to space-time block code to obtain frequency diversity. Performance bounds and simulation results show that the bit-interleaved space-time coded OFDM system can effectively exploit both space and frequency diversity to improve performance.
43 citations
Cites background from "Space-frequency turbo coded OFDM"
...Space-time (or space-frequency) trellis coded OFDM in [1], [5], [14] and space-frequency turbo coded OFDM in [17] are considered to exploit both space and frequency diversity....
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TL;DR: A design method for recursive space- time trellis codes and parallel-concatenated space-time turbo coded modulation is proposed that enables a large, systematic increase in coding gain while preserving the maximum transmit diversity gain and bandwidth efficiency property of the considered space- Time Trellis code.
Abstract: A design method for recursive space-time trellis codes and parallel-concatenated space-time turbo coded modulation is proposed that can be applied to an arbitrary existing space-time trellis code. The method enables a large, systematic increase in coding gain while preserving the maximum transmit diversity gain and bandwidth efficiency property of the considered space-time trellis code. Applying the above method to Tarokh et al. space-time trellis codes, significant performance improvements can be obtained even with extremely short input information frames. The application of space-time turbo coded modulation to the space-frequency domain is also proposed in this paper. Exploiting the bandwidth efficient orthogonal frequency division modulation (OFDM), multiple transmit antennas and large frequency selectivity offered by typical low mobility indoor environments, the proposed space-frequency turbo coded modulation performs within 2.5 dB of the outage capacity for a variety of practical wideband multiple-input multiple-output (MIMO) radio channels.
33 citations
TL;DR: The bit error rate of a synchronous multicarrier code-division multiple-access system operating in a Rayleigh fading channel is calculated based on a moment generating function method, without any assumption on the distribution of multiple access interference.
Abstract: The bit error rate of a synchronous multicarrier code-division multiple-access system operating in a Rayleigh fading channel is calculated based on a moment generating function method, without any assumption on the distribution of multiple access interference. Two closed-form BER expressions are derived. Moreover, the BER can be accurately evaluated by using a Gauss-Chebyshev quadrature rule based numerical approach.
33 citations
01 Jan 2003
TL;DR: This paper considers transmission of OFDM modulated signals over MIMO frequency-selective fading channels using a set of low-complexity MMSE SISO equalizers, achieving both spatial-interference mitigation and demodulation.
Abstract: This paper considers transmission of OFDM modulated signals over MIMO frequency-selective fading channels. To benefit from diversity, coding is introduced in the space and frequency dimensions by means of bit-interleaved coded modulation. Assuming the OFDM cyclic extension works properly, MIMO space equalization has to be performed for each individual tone. A set of low-complexity MMSE SISO equalizers, achieving both spatial-interference mitigation and demodulation, is used. This set of MMSE equalizers exchanges soft information with the SISO decoder according to the turbo principle. The performance of this scheme is illustrated by computer simulations for quasistatic frequency-selective channels. It is shown that this receiver is able to exploit space and frequency diversity.
19 citations
04 Dec 2007
TL;DR: W Welch-Costas array pattern is derived under independent and cluster hopping schemes, which enable the system performance with the Turbo code modulation scheme to be evaluated.
Abstract: The performance of frequency hopped OFDM cellular system depends on the designing of frequency hopping sequences. This paper explores fast frequency hopped OFDM in the link level of a cellular communication system. Each user is assigned several sub-carriers by the base station in each cell in every time slot according to the predetermined hopping sequences. The frequency hopped OFDM technique based on orthogonal hopping sequences can improve communication performance in a cellular system since it could minimize intra-cell interference and average inter-cell interference. In this paper, Welch-Costas array pattern is derived under independent and cluster hopping schemes, which enable us to evaluate the system performance with the Turbo code modulation scheme. Examples of the frequency sequences and how they are assigned to users are also given. We also simulate and analyze the impacts of the channel environment and parameters, frequency diversity, and inter-cell interference diversity on the performance of the coded frequency hopped OFDM cellular system.
7 citations
Cites methods from "Space-frequency turbo coded OFDM"
...In the encoding module, we explore the system performance with Turbo coding [ 9 ]....
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References
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01 Nov 1999
TL;DR: In this paper, the authors investigate the use of multiple transmitting and/or receiving antennas for single user communications over the additive Gaussian channel with and without fading, and derive formulas for the capacities and error exponents of such channels, and describe computational procedures to evaluate such formulas.
Abstract: We investigate the use of multiple transmitting and/or receiving antennas for single user communications over the additive Gaussian channel with and without fading. We derive formulas for the capacities and error exponents of such channels, and describe computational procedures to evaluate such formulas. We show that the potential gains of such multi-antenna systems over single-antenna systems is rather large under independenceassumptions for the fades and noises at different receiving antennas.
12,542 citations
TL;DR: In this article, the authors examined the performance of using multi-element array (MEA) technology to improve the bit-rate of digital wireless communications and showed that with high probability extraordinary capacity is available.
Abstract: This paper is motivated by the need for fundamental understanding of ultimate limits of bandwidth efficient delivery of higher bit-rates in digital wireless communications and to also begin to look into how these limits might be approached. We examine exploitation of multi-element array (MEA) technology, that is processing the spatial dimension (not just the time dimension) to improve wireless capacities in certain applications. Specifically, we present some basic information theory results that promise great advantages of using MEAs in wireless LANs and building to building wireless communication links. We explore the important case when the channel characteristic is not available at the transmitter but the receiver knows (tracks) the characteristic which is subject to Rayleigh fading. Fixing the overall transmitted power, we express the capacity offered by MEA technology and we see how the capacity scales with increasing SNR for a large but practical number, n, of antenna elements at both transmitter and receiver.
We investigate the case of independent Rayleigh faded paths between antenna elements and find that with high probability extraordinary capacity is available. Compared to the baseline n = 1 case, which by Shannon‘s classical formula scales as one more bit/cycle for every 3 dB of signal-to-noise ratio (SNR) increase, remarkably with MEAs, the scaling is almost like n more bits/cycle for each 3 dB increase in SNR. To illustrate how great this capacity is, even for small n, take the cases n = 2, 4 and 16 at an average received SNR of 21 dB. For over 99% of the channels the capacity is about 7, 19 and 88 bits/cycle respectively, while if n = 1 there is only about 1.2 bit/cycle at the 99% level. For say a symbol rate equal to the channel bandwith, since it is the bits/symbol/dimension that is relevant for signal constellations, these higher capacities are not unreasonable. The 19 bits/cycle for n = 4 amounts to 4.75 bits/symbol/dimension while 88 bits/cycle for n = 16 amounts to 5.5 bits/symbol/dimension. Standard approaches such as selection and optimum combining are seen to be deficient when compared to what will ultimately be possible. New codecs need to be invented to realize a hefty portion of the great capacity promised.
10,526 citations
TL;DR: In this paper, the authors consider the design of channel codes for improving the data rate and/or the reliability of communications over fading channels using multiple transmit antennas and derive performance criteria for designing such codes under the assumption that the fading is slow and frequency nonselective.
Abstract: We consider the design of channel codes for improving the data rate and/or the reliability of communications over fading channels using multiple transmit antennas. Data is encoded by a channel code and the encoded data is split into n streams that are simultaneously transmitted using n transmit antennas. The received signal at each receive antenna is a linear superposition of the n transmitted signals perturbed by noise. We derive performance criteria for designing such codes under the assumption that the fading is slow and frequency nonselective. Performance is shown to be determined by matrices constructed from pairs of distinct code sequences. The minimum rank among these matrices quantifies the diversity gain, while the minimum determinant of these matrices quantifies the coding gain. The results are then extended to fast fading channels. The design criteria are used to design trellis codes for high data rate wireless communication. The encoding/decoding complexity of these codes is comparable to trellis codes employed in practice over Gaussian channels. The codes constructed here provide the best tradeoff between data rate, diversity advantage, and trellis complexity. Simulation results are provided for 4 and 8 PSK signal sets with data rates of 2 and 3 bits/symbol, demonstrating excellent performance that is within 2-3 dB of the outage capacity for these channels using only 64 state encoders.
7,105 citations
TL;DR: This paper describes the statistical models of fading channels which are frequently used in the analysis and design of communication systems, and focuses on the information theory of fading channel, by emphasizing capacity as the most important performance measure.
Abstract: In this paper we review the most peculiar and interesting information-theoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information theory of fading channels, by emphasizing capacity as the most important performance measure. Both single-user and multiuser transmission are examined. Further, we describe how the structure of fading channels impacts code design, and finally overview equalization of fading multipath channels.
2,017 citations
"Space-frequency turbo coded OFDM" refers background in this paper
...Calculating the capacity of frequencyselective channel, Shannon has demonstrated that slicing the bandwidth into infinitesimal, flat sub-bands represent a capacity approaching signaling strategy [21, 22 ]....
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TL;DR: This paper shows that the presence of multipath greatly improves achievable data rate if the appropriate communication structure is employed, and an adaptive-lattice trellis-coding technique is suggested as a method for coding across the space and frequency dimensions that exist in the DMMT channel.
Abstract: Multipath signal propagation has long been viewed as an impairment to reliable communication in wireless channels. This paper shows that the presence of multipath greatly improves achievable data rate if the appropriate communication structure is employed. A compact model is developed for the multiple-input multiple-output (MIMO) dispersive spatially selective wireless communication channel. The multivariate information capacity is analyzed. For high signal-to-noise ratio (SNR) conditions, the MIMO channel can exhibit a capacity slope in bits per decibel of power increase that is proportional to the minimum of the number multipath components, the number of input antennas, or the number of output antennas. This desirable result is contrasted with the lower capacity slope of the well-studied case with multiple antennas at only one side of the radio link. A spatio-temporal vector-coding (STVC) communication structure is suggested as a means for achieving MIMO channel capacity. The complexity of STVC motivates a more practical reduced-complexity discrete matrix multitone (DMMT) space-frequency coding approach. Both of these structures are shown to be asymptotically optimum. An adaptive-lattice trellis-coding technique is suggested as a method for coding across the space and frequency dimensions that exist in the DMMT channel. Experimental examples that support the theoretical results are presented.
1,593 citations