New mapping schemes for multi-dimensional constellation in MIMO-BICH-ID systems

Recently, Multiple Input and Multiple Output (MIMO) systems have shown a tremendous potential to increase the spectral efficiency and the reliability of wireless communication. These aspects are quantified in terms of the spatial multiplexing gain and the diversity gain respectively. It was shown that there is a trade-off between diversity and multiplexing gains. Bit Interleaved Coded Modulation with Iterative Decoding (BICM-ID) for Multiple Input and Multiple Output channels has recently been addressed as an effective mean to achieve high data rates while maintaining high diversity. It has been shown that, when signal constellation, interleaver and error control code are fixed, signal mapping has a crucial influence on the error performance of a BICM-ID system. The role of signal mapping applies to the error performance of MIMO-BICM-ID system. In this thesis, the design of constellation mapping for MIMO-BICM-ID system is studied. Based on minimizing pair-wise error probability, a design criterion is proposed to find the optimal constellation mapping for MIMO-BICM-ID. To reduce computational complexity of exhaustive search, Binary Switching Algorithm is improved to find the optimal solution. Using the design criterion and employing the Binary Switching Algorithm, some optimal constellation mappings are found for 2-dimensional and 3-dimensional cases. A measurement based on mutual information is developed to evaluate the proposed constellation mappings. It is shown that proposed mappings sacrifice bit-wise mutual information without a priori information but improve significantly when perfect a priori knowledge is available. At the receiver, to avoid the computational complexity of the optimal Maximum-Likelihood (NIL) detector, List Sphere Decoder (LSD) is used as the inner detector. Simulation results demonstrate that proposed schemes outperform conventional ones significantly at high signal to noise ratio (SNR) over fading channels. System simulations are carried out specifically for 2-dimensional QPSK, 2-dimensional 8QAM and 3-dimensional QPSK constellations/mappings. Results show an improvement of 1.3 dB, 1.6 dB and 1.8 dB compared to conventional constellation mappings over slow fading channels, respectively. This improvement increase to 3.5 dB, 2.7 dB and 2.4 dB for fast fading channel

Iterative decoding for MIMO channels via modified sphere decoding

In recent years, soft iterative decoding techniques have been shown to greatly improve the bit error rate performance of various communication systems. For multiantenna systems employing space-time codes, however, it is not clear what is the best way to obtain the soft information required of the iterative scheme with low complexity. In this paper, we propose a modification of the Fincke-Pohst (sphere decoding) algorithm to estimate the maximum a posteriori probability of the received symbol sequence. The new algorithm solves a nonlinear integer least squares problem and, over a wide range of rates and signal-to-noise ratios, has polynomial-time complexity. Performance of the algorithm, combined with convolutional, turbo, and low-density parity check codes, is demonstrated on several multiantenna channels. The results for systems that employ space-time modulation schemes seem to indicate that the best performing schemes are those that support the highest mutual information between the transmitted and received signals, rather than the best diversity gain

Design guidelines for spatial modulation

A new class of low-complexity, yet energyefficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO) has emerged. These systems are capable of exploiting the spatial dimensions (i.e. the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication whilst relying on a single-Radio Frequency (RF) chain. Moreover, SM may also be viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/ cooperative protocol design issues, and on their meritorious variants

Spatial Multiplexing of QPSK Signals with a Single Radio: Antenna Design and Over-the-Air Experiments

The paper describes the implementation and performance analysis of the first fully-operational beam-space MIMO antenna for the spatial multiplexing of two QPSK streams. The antenna is composed of a planar three-port radiator with two varactor diodes terminating the passive ports. Pattern reconfiguration is used to encode the MIMO information onto orthogonal virtual basis patterns in the far-field. A measurement campaign was conducted to compare the performance of the beam-space MIMO system with a conventional 2-by-?2 MIMO system under realistic propagation conditions. Propagation measurements were conducted for both systems and the mutual information and symbol error rates were estimated from Monte-Carlo simulations over the measured channel matrices. The results show the beam-space MIMO system and the conventional MIMO system exhibit similar finite-constellation capacity and error performance in NLOS scenarios when there is sufficient scattering in the channel. In comparison, in LOS channels, the capacity performance is observed to depend on the relative polarization of the receiving antennas.Comment: 31 pages, 23 figure

Cyclic division algebras: a tool for space-time coding

Multiple antennas at both the transmitter and receiver ends of a wireless digital transmission channel may increase both data rate and reliability. Reliable high rate transmission over such channels can only be achieved through Space–Time coding. Rank and determinant code design criteria have been proposed to enhance diversity and coding gain. The special case of full-diversity criterion requires that the difference of any two distinct codewords has full rank. Extensive work has been done on Space–Time coding, aiming at finding fully diverse codes with high rate. Division algebras have been proposed as a new tool for constructing Space–Time codes, since they are non-commutative algebras that naturally yield linear fully diverse codes. Their algebraic properties can thus be further exploited to improve the design of good codes. The aim of this work is to provide a tutorial introduction to the algebraic tools involved in the design of codes based on cyclic division algebras. The different design criteria involved will be illustrated, including the constellation shaping, the information lossless property, the non-vanishing determinant property, and the diversity multiplexing trade-off. The final target is to give the complete mathematical background underlying the construction of the Golden code and the other Perfect Space–Time block codes

Minimum BER Precoding in 1-Bit Massive MIMO Systems

1-bit digital-to-analog (DACs) and analog-to-digital converters (ADCs) are gaining more interest in massive MIMO systems for economical and computational efficiency. We present a new precoding technique to mitigate the inter-user-interference (IUI) and the channel distortions in a 1-bit downlink MUMISO system with QPSK symbols. The transmit signal vector is optimized taking into account the 1-bit quantization. We develop a sort of mapping based on a look-up table (LUT) between the input signal and the transmit signal. The LUT is updated for each channel realization. Simulation results show a significant gain in terms of the uncoded bit-error-ratio (BER) compared to the existing linear precoding techniques.Comment: Presented in IEEE SAM 2016, 10th-13th July 2016, Rio De Janeiro, Brazi