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

A virtual MIMO dual-hop architecture based on hybrid spatial modulation

International audienceIn this paper, we propose a novel Virtual Multiple-Input-Multiple-Output (VMIMO) architecture based on the concept of Spatial Modulation (SM). Using a dual-hop and Decode-and-Forward protocol, we form a distributed system, called Dual-Hop Hybrid SM (DH-HSM). DH-HSM conveys information from a Source Node (SN) to a Destination Node (DN) via multiple Relay Nodes (RNs). The spatial position of the RNs is exploited for transferring information in addition to, or even without, a conventional symbol. In order to increase the performance of our architecture, while keeping the complexity of the RNs and DN low, we employ linear precoding using Channel State Information (CSI) at the SN. In this way, we form a Receive-Spatial Modulation (R-SM) pattern from the SN to the RNs, which is able to employ a centralized coordinated or a distributed uncoordinated detection algorithm at the RNs. In addition, we focus on the SN and propose two regularized linear precoding methods that employ realistic Imperfect Channel State Information at the Transmitter. The power of each precoder is analyzed theoretically. Using the Bit Error Rate (BER) metric, we evaluate our architecture against the following benchmark systems: 1) single relay; 2) best relay selection; 3) distributed Space Time Block Coding (STBC) VMIMO scheme; and 4) the direct communication link. We show that DH-HSM is able to achieve significant Signal-to-Noise Ratio (SNR) gains, which can be as high as 10.5 dB for a very large scale system setup. In order to verify our simulation results, we provide an analytical framework for the evaluation of the Average Bit Error Probability (ABEP)

Spatial Modulation for Multiple-Antenna Wireless Systems : A Survey

International audienceMultiple-antenna techniques constitute a key technology for modern wireless communications, which trade-off superior error performance and higher data rates for increased system complexity and cost. Among the many transmission principles that exploit multiple-antenna at either the transmitter, the receiver, or both, Spatial Modulation (SM) is a novel and recently proposed multiple- uniqueness and randomness properties of the wireless channel for communication. This is achieved by adopting a simple but effective coding mechanism that establishes a one-to-one mapping between blocks of information bits to be transmitted and the spatial positions of the transmit-antenna in the antenna-array. In this article, we summarize the latest research achievements and outline some relevant open research issues of this recently proposed transmission technique

On the Performance of Full-duplex Two-way Relay Channels with Spatial Modulation

In this paper, the spatial modulation (SM) technique is employed at the source and relay nodes in a full-duplex twoway relay channel (FD-TWRC) to support spectral-efficient bidirectional communications while guaranteeing a low cost implementation. Maximum likelihood (ML) detectors are employed at each node that is subject to an intrinsic self-loop interference (SI). We first propose a tight upper bound on the average bit error probability (ABEP). Then based on the ABEP upper bound, an asymptotic ABEP expression is derived in the high SNR regime. Exploiting the asymptotic ABEP, an exact SNR threshold for the selection between FD-TWRC-SM and half-duplex (HD)-TWRCSM is derived in a closed form, which sheds light on when it is beneficial to select the FD (or HD) mode. In addition, the power allocation (PA) among sources and relay is investigated, through which an optimal PA factor in terms of ABEP is obtained. All analytical results derived in this paper are verified by Monte Carlo simulations, from which some new insights are obtained on the performance of FD-TWRC-SM

Extension and practical evaluation of the spatial modulation concept

The spatial modulation (SM) concept combines, in a novel fashion, digital modulation and multiple antenna transmission for low complexity and spectrally efficient data transmission. The idea considers the transmit antenna array as a spatial constellation diagram with the transmit antennas as the constellation points. To this extent, SM maps a sequence of bits onto a signal constellation point and onto a spatial constellation point. The information is conveyed by detecting the transmitting antenna (the spatial constellation point) in addition to the signal constellation point. In this manner, inter-channel interference is avoided entirely since transmission is restricted to a single antenna at any transmission instance. However, encoding binary information in the spatial domain means that the number of transmit antennas must be a power of two. To address this constraint, fractional bit encoded spatial modulation (FBE—SM) is proposed. FBE–SMuses the theory of modulus conversion to facilitate fractional bit rates over time. In particular, it allows each transmitter to use an arbitrary number of transmit antennas. Furthermore, the application of SM in a multi-user, interference limited scenario has never been considered. To this extent, the average bit error rate (ABER) of SM is characterised in the interference limited scenario. The ABER performance is first analysed for the interference-unaware detector. An interference-aware detector is then proposed and compared with the cost and complexity equivalent detector for a single–input multiple–output (SIMO) system. The application of SM with an interference-aware detector results in coding gains for the system. Another area of interest involves using SM for relaying systems. The aptitude of SM to replace or supplement traditional relaying networks is analysed and its performance is compared with present solutions. The application of SM to a fixed relaying system, termed dual-hop spatial modulation (Dh-SM), is shown to have an advantage in terms of the source to destination ABER when compared to the classical decode and forward (DF) relaying scheme. In addition, the application of SM to a relaying system employing distributed relaying nodes is considered and its performance relative to Dh-SM is presented. While significant theoretical work has been done in analysing the performance of SM, the implementation of SM in a practical system has never been shown. In this thesis, the performance evaluation of SM in a practical testbed scenario is presented for the first time. To this extent, the empirical results validate the theoretical work presented in the literature

End-to-End Joint Antenna Selection Strategy and Distributed Compress and Forward Strategy for Relay Channels

Multi-hop relay channels use multiple relay stages, each with multiple relay nodes, to facilitate communication between a source and destination. Previously, distributed space-time codes were proposed to maximize the achievable diversity-multiplexing tradeoff, however, they fail to achieve all the points of the optimal diversity-multiplexing tradeoff. In the presence of a low-rate feedback link from the destination to each relay stage and the source, this paper proposes an end-to-end antenna selection (EEAS) strategy as an alternative to distributed space-time codes. The EEAS strategy uses a subset of antennas of each relay stage for transmission of the source signal to the destination with amplify and forwarding at each relay stage. The subsets are chosen such that they maximize the end-to-end mutual information at the destination. The EEAS strategy achieves the corner points of the optimal diversity-multiplexing tradeoff (corresponding to maximum diversity gain and maximum multiplexing gain) and achieves better diversity gain at intermediate values of multiplexing gain, versus the best known distributed space-time coding strategies. A distributed compress and forward (CF) strategy is also proposed to achieve all points of the optimal diversity-multiplexing tradeoff for a two-hop relay channel with multiple relay nodes.Comment: Accepted for publication in the special issue on cooperative communication in the Eurasip Journal on Wireless Communication and Networkin

New challenges in wireless and free space optical communications

AbstractThis manuscript presents a survey on new challenges in wireless communication systems and discusses recent approaches to address some recently raised problems by the wireless community. At first a historical background is briefly introduced. Challenges based on modern and real life applications are then described. Up to date research fields to solve limitations of existing systems and emerging new technologies are discussed. Theoretical and experimental results based on several research projects or studies are briefly provided. Essential, basic and many self references are cited. Future researcher axes are briefly introduced

Exploiting spatial modulation and analog network coding for the design of energy-efficient wireless networks

As the data rate demands of the cellular users increase, together with their number, it is expected that unprecedented capacity demands should be met in wireless networks in the forthcoming years. However, the energy consumption to meet these rates is expected to increase exponentially, according to trends. This can become a serious issue for both the environment, due to CO2 emissions, and the operators, which will have to pay more for electricity. Hence, several energy-efficient solutions have been proposed, such as multiple antenna systems, dynamic spectrum allocation, heterogeneous networks, and Network Coding, to name a few. Based on the above, the aim of this thesis to propose low-complexity and energy-efficient physical layer-based solutions compared to the already existing approaches, without sacrificing the quality of performance. More specifically, the focus is on the technologies of Spatial Modulation and Analog Network Coding. Both schemes offer the so-called multiplexing gain, which means that multiple streams can be transmitted without sacrificing resources, such as bandwidth. As far as Spatial Modulation is concerned, Spatial Modulation-based schemes are proposed that are more energy efficient than state-of-the-art technologies. Regarding Analog Network Coding, we study its implementation in relay-based scenarios and how it compares in terms of energy efficiency with conventional protocols, such as the time-division multiple access protocol. From the obtained results, the conclusion that can be drawn is that depending on the scenario both Spatial Modulation and Analog Network Coding can provide significant energy gains compared to existing technologies without sacrificing performance.A medida que las demandas de velocidad de datos de los usuarios de redes celulares aumentan, así como su número, se espera que las demandas de capacidad sin precedentes se deban cumplir en las redes inalámbricas en los próximos años. Sin embargo, se espera que aumente de forma exponencial el consumo de energía para satisfacer estas tasas, de acuerdo a las tendencias. Esto puede convertirse en un grave problema ambos para el medio ambiente, debido a las emisiones de CO2, y los operadores, que tendrán que pagar más por la electricidad. Por lo tanto, se han propuesto varias soluciones de eficiencia energética, tales como sistemas de múltiples antenas, la asignación de espectro dinámico, redes heterogéneas, y Network Coding, para nombrar unos pocos. Con base en lo anterior, el objetivo de esta tesis es proponer soluciones de baja complejidad y de eficiencia energética basadas en la capa física, en comparación con los enfoques ya existentes, sin sacrificar la calidad del funcionamiento. Más específicamente, la atención se centra en las tecnologías de Spatial Modulation y Analog Network Coding. Ambos esquemas ofrecen la llamada ganancia de multiplexación, lo que significa que múltiples flujos pueden ser transmitidos sin sacrificar recursos, tales como el ancho de banda. En lo que se refiere a Spatial Modulation, se proponen esquemas basados en Spatial Modulation que son más energéticamente que tecnologías ya existentes. En cuanto a Analog Network Coding, se estudia su aplicación en escenarios inalámbricos basados en relays y cómo se compara en términos de eficiencia energética con los protocolos convencionales, tales como el protocolo de acceso mútiple por división de tiempo. De los resultados obtenidos, la conclusión que se puede extraer es que dependiendo del escenario, ambos Spatial Modulation y Analog Network Coding pueden proporcionar beneficios significativos de energía en comparación con las tecnologías existentes sin sacrificar el funcionamiento