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The following topics were dealt with: properties of codes; feedback and cooperation in networks; channel coding, communication techniques and estimation methods; construction, analysis and decoding of LDPC codes; sequences and permutations; universal lossless compression; capacity and coding for fading channels; network theory; statistical mechanics; turbo and turbo-like code constructions; communication...
We study the capacity behavior of full-band MIMO-OFDM systems in the absence of channel state information both at the transmitter and the receiver. Based on capacity lower and upper bounds, we quantify the transmission rate penalty due to channel uncertainty as a function of the number of transmit antennas, the number of resolvable taps in the channel, the power delay profile, and the bandwidth. Our...
We consider the pulse design problem in multicarrier transmission where the pulse shapes are adapted to the second order statistics of the WSSUS channel. Even though the problem has been addressed by many authors analytical insights are rather limited. First we show that the problem is equivalent to the pure state channel fidelity in quantum information theory. Next we present a new approach where...
In this paper new codes for orthogonal frequency-division multiplexing (OFDM) with tightly controlled peak-to-mean envelope power ratio (PMEPR) are proposed. We identify a new family of sequences occurring in complementary sets and show that such sequences form subsets of a new generalization of the Reed-Muller codes. Contrarily to previous constructions we present a compact description of such codes,...
In this paper, we introduce a new partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM) scheme with low computational complexity. In the proposed scheme, 2n - point inverse fast Fourier transform (IFFT) is divided into two parts. An input symbol sequence is partially transformed using the first l stages of IFFT to generate an intermediate signal sequence and the intermediate...
One of UWB proposal in IEEE P802.15 WPAN project is to use OFDM system and punctured convolutional codes for UWB channels supporting data rate up to 480 Mb/s. We apply a TTCM encoder to examine the possible improvement for UWB/OFDM. We construct punctured parity-concatenated trellis codes in which a TCM code is used as the inner code and a simple parity-check code is used as the outer code. The bit...
It is known that in an OFDM system using Hadamard transform or phase alteration before the IDFT operation can reduce the peak-to-average power ratio (PAPR). Both these techniques can be viewed as constellation preceding for PAPR reduction. In general, using non-diagonal transforms, like Hadamard transform, increases the ML decoding complexity. In this paper we propose the use of block-IDFT matrices...
A new design method for high rate, fully diverse ('spherical') space frequency codes for MIMO-OFDM systems is proposed, which works for arbitrary numbers of antennas and subcarriers. The construction exploits a differential geometric connection between spherical codes and space time codes. The former are well studied e.g. in the context of optimal sequence design in CDMA systems, while the latter...
In this paper we derive the optimal diversity versus multiplexing tradeoff for a frequency selective i.i.d. Rayleigh MIMO channel. This tradeoff is shown to be better than the one of the frequency flat MIMO channel. Traditional approaches for frequency selective channels use OFDM techniques in order to exploit the diversity gain due to frequency selectivity. We show that although coding in OFDM over...
This paper presents a systematic construction of high-rate and full-diversity space-frequency block codes for MIMO-OFDM systems. While all prior constructions offer only a maximum rate of one complex symbol per channel use, our construction yields rate equal to the number of transmit antennas and simultaneously achieves full-diversity. The proposed construction works for arbitrary number of transmit...
It is known that multi-antenna transmissions over frequency-selective channels can provide a diversity gain that is product of the number of transmit antennas, the receive antennas and the length of the channel impulse response. Liu, Xin and Giannakis have studied multi-antenna orthogonal frequency division multiplexing (OFDM) through frequency-selective Rayleigh-fading channels and have introduced...
Constructions of space-frequency (SF) codes for MIMO-OFDM systems with nt transmit antennas and Q subcarriers are considered in this paper. Arising from the pairwise-error-probability analysis, in addition to the rank distance criterion, the minimum column distance of (nt times Q) SF codes serves as another benchmark in code design. Codes with larger minimum column distance are expected to have better...
It is known that by employing space-time-frequency codes (STFCs) to frequency selective MIMO-OFDM systems, all the three diversity viz spatial, temporal and multipath can be exploited. There exists space-time-frequency block codes (STFBCs) designed using orthogonal designs with constellation precoder to get full diversity (Z. Liu, Y. Xin and G. Giannakis IEEE Trans. Signal Processing, Oct. 2002)....
This paper considers the power allocation for a multiuser MIMO-OFDM downlink system using zero-forcing multiplexing, with the objective to maximize the system capacity. An optimal power allocation algorithm has been developed and is presented. While the optimal power allocation algorithm achieves promising capacity, its complexity increases exponentially with the number of users. We develop two power...
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