Antoine O. Berthet

Frequency-Domain Block Turbo-Equalization for Single-Carrier Transmission Over MIMO Broadband Wireless Channel

This paper presents a new class of block turbo-equalizers for single-carrier transmission over multiple-input multiple-output (MIMO) broadband wireless channels. The key underlying idea consists in equalizing (nonoverlapping) groups of symbols and detecting their individual space-time components in a disjoint and iterative fashion. This functional split naturally induces new design options that have been accurately listed and described, i.e., choice of distinct criteria for intergroup interference (IGI) equalization and intragroup components detection, yielding hybrid structures, multiple iterative loops, and related scheduling variants. Selected algorithms in the proposed class are compared in terms of performance under various transmission scenarios. For all of them, minimum mean square error IGI equalization certainly occupies a central role (at least for the first iteration) and may be identified as the computational bottleneck. Fortunately, block spread transmission together with cyclic prefix operations make the channel matrix block circulant, thus allowing low-complexity inversion in the Fourier domain

A new class of iterative equalizers for space-time BICM over MIMO block fading multipath AWGN channel

This paper addresses the issue of advanced equalization methods for space-time communications over multiple-input multiple-output block fading channel with intersymbol interference. Instead of resorting to conventional multiuser detection techniques (based on the straightforward analogy between antennas and users), we adopt a different point of view, and separate time equalization from space equalization, thus introducing a higher degree of freedom in the overall space-time equalizer design. Time-domain equalization relies on minimum mean-square error criterion and operates on multidimensional modulation symbols, whose individual components can be detected in accordance with another criterion. In particular, when the optimum maximum a posteriori criterion is chosen, substantial performance gains over conventional space-time turbo equalization have been observed for different transmission scenarios, at the price of an increased, albeit manageable, computational complexity.

Iterative data detection and channel estimation for advanced TDMA systems

This letter presents a new receiver for Q-ary transmission, where all receiver blocks are embedded in an iterative structure. Packet data transmission in Global Systems for Mobile communications (GSM) and Enhanced Data rates for Global Evolution (EDGE) are considered as examples. A low-complexity soft-in-soft-out detector for EDGE is introduced and its modification suitable for iterative detection is derived. Application of iterative detection and channel estimation techniques in GSM/EDGE shows a significant performance enhancement. Additional improvement may be obtained if the iterative processing is applied to packet retransmission schemes.

Joint channel-network turbo coding for the non-orthogonal multiple access relay channel

In this paper, we investigate the benefit of joint network-channel distributed coding for the multiple-access half-duplex relay channel. In contrast with previous work, the medium access is not orthogonal and the source-to-relay links are not error-free, which render the reality of wireless environments and notably complicate the problem. Indeed, due to the broadcast nature of wireless media, transmitted signals interfere at the relay and at the destination and form multiple-access channels. This entails the need of more sophisticated joint multiuser detection and decoding procedures. Moreover, improper (erroneous) distributed codes may result from unsuccessful decoding at the relay. This second issue is handled with selection relaying. We describe in detail the structure of the encoders, when and how JNC coding is performed, and the structure of the joint multiuser detectors and decoders. For a given spectral efficiency, we show through simulations that our approach provides substantial performance gains compared to conventional joint network-channel distributed coding for the orthogonal multiple-access half-duplex relay channel. Equivalently, for a targeted performance, our approach allows to transmit at higher rates.

A Novel Fast Semi-Analytical Performance Prediction Method for Iterative MMSE-IC Multiuser MIMO Joint Decoding

This paper presents a novel fast performance prediction method for iterative minimum-mean square error interference cancellation based joint decoding in a very general multiuser MIMO setting considering a transmission over block-fading frequency-selective channels. A Gaussian approximation is made for all propagated messages between the outer codes and the space-time multiuser detector. The method relies on a signal-to-interference-plus-noise ratio compression, by means of the mutual information effective signal-to-noise metric (MIESM), which allows a one-dimensional AWGN look-up table to capture the soft decoding result of each distinct user. Simulations show that this method while being extremely simple and fast keeps very accurate and is thus adequate for radio resource management and link adaptation purposes.

Full Diversity Distributed Coding for the Multiple Access Half-Duplex Relay Channel

In this paper, we investigate the benefit of joint network-channel (JNC) distributed coding for the semi-orthogonal multiple-access half-duplex relay channel. The sources are allowed to transmit simultaneously during the listening phase of the relay, while during the relay transmission phase, they are constrained to remain silent. In contrast with previous work, we introduce a general framework for the relaying function, based on a selective approach, which depends on the number of correctly decoded messages. We also study the conditions where the introduced relaying function ensure the full diversity at the destination. We describe in detail the structure of the encoders, JNC coding, and the joint multiuser receiver structure. For a given spectral efficiency, we show through simulations that our approach provides substantial coding and diversity gains compared to existing schemes.

Outage achievable rate analysis for the Non Orthogonal Multiple Access Multiple Relay Channel

In this paper, we derive the individual and common symmetric ε-outage achievable rate for the relay assisted cooperative communication scheme, coined Non Orthogonal Multiple Access Multiple Relay Channel (NOMAMRC), defined as follows: (1) The sources are independent and want to communicate with a single destination with the help of multiple relays; (2) Each relay is half-duplex and apply a Selective Decode and Forward (SDF) strategy, i.e., it forwards only a deterministic function of the error-free decoded messages; (3) The sources are allowed to transmit simultaneously during both the listening and transmission phases of the relays. In this paper, the links are independent. No channel state information at transmitter is available, each link follows a slow Rayleigh fading distribution.

Joint Channel-Network Coding for the Semi-Orthogonal Multiple Access Relay Channel

In this paper, a joint channel-network coding is proposed for the multiple access half duplex relay channel. To improve performance, the classical constraints of orthogonality between links are partially relaxed, i.e., in the first transmission phase the two sources are allowed to transmit simultaneously, while in the second phase, the relay transmits alone and the sources are silent. In order to resolve the subsequent collisions occurring at the relay and destination, related iterative multiuser detection structures are suggested. Simulation results demonstrate the superiority of the proposed semi-orthogonal transmission protocol compared to the orthogonal one.

A class of low complexity iterative equalizers for space-time BICM over MIMO block fading multipath AWGN channel

In this paper, we propose a class of iterative equalizers for space-time bit interleaved coded modulation over MIMO block fading multipath AWGN channel. Simulations show that the proposed receivers are able to reach the matched-filter bound and that the tested space-time coding schemes have the potential to get close to the Shannon theoretical limit.

Binary versus symbolic performance prediction methods for iterative MMSE-IC multiuser MIMO joint decoding

This paper presents a dual mode fast performance prediction method for iterative minimum-mean square error interference cancellation based joint decoding in a very general multiuser MIMO setting, considering a transmission over block-fading frequency-selective channels. The symbolic mode relies on a signal to interference-plus-noise ratio compression at symbol level, by means of the Mutual Information Effective Signal-to- noise Metric (MIESM), bridging the gap between the EXtrinsic Information Transfer (EXIT) charts and the compression methods developed for Link-to-System interface. The binary mode follows the classical EXIT chart approach relying on a new analytical formula of the Bit Interleaved Coded Modulation average mutual information in presence of non-uniform a priori on input bits. This paper demonstrates the superiority of the symbolic mode for high order modulation.