Academic literature on the topic 'Generalised Spatial Modulation'

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA<br>Spatial modulation (SM) is a transmission scheme where only one transmit antenna is active at any time instant. It thus reduces interchannel interference (ICI) and receiver complexity over traditional multi-antenna systems. However, the spectral efficiency of SM is low. To improve the spectral efficiency, generalized spatial modulation (GSM) can be used. In this paper, we propose to apply the Alamouti technique with GSM for correlated antennas, and show that the proposed approach provides significant improvement over conventional SM and GSM. Our study also shows the importance of bit-to-antenna mappings and their roles on the selection of appropriate correlated antennas.

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV<br>Spatial modulation (SM) reduces transceiver complexity and inter-channel interference over traditional multiple input multiple output (MIMO) systems. It has been shown recently in the literature that the use of a precoder in an SM or a generalized spatial modulation (GSM) system can significantly improve error performance. This paper investigates two issues related to precoders: 1) the use of a precoder in Alamouti-GSM systems, and 2) the effects of power constraints on the precoder design. The results in this paper show that Alamouti-GSM can improve system performance by several dB. On power constraint issues, the paper shows that there is a trade-off between limiting antenna power fluctuations and the potential gain due to precoders.

The present study analyses three beam shaping approaches with respect to a light-efficient generation of i) patterns and ii) multiple spots by means of a generic optical 4f-setup. 4f approaches share the property that due to the one-to-one relationship between output intensity and input phase, the need for time-consuming, iterative calculation can be avoided. The resulting low computational complexity offers a particular advantage compared to the widely used holographic principles and makes them potential candidates for real-time applications. The increasing availability of high-speed phase modulators, e.g. on the basis of MEMS, calls for an evaluation of the performances of these concepts. Our second interest is the applicability of 4f methods to high-power applications. We discuss the variants of 4f intensity shaping by phase modulation from a system-level point of view which requires the consideration of application relevant boundary conditions. The discussion includes i) the micro mirror based phase manipulation combined with amplitude masking in the Fourier plane, ii) the Generalized Phase Contrast, and iii) matched phase-only correlation filtering combined with GPC. The conceptual comparison relies on comparative figures of merit for energy efficiency, pattern homogeneity, pattern image quality, maximum output intensity and flexibility with respect to the displayable pattern. Numerical simulations illustrate our findings.

A novel energy efficient Multiple-Input-Multiple-Output (MIMO) technique is called Spatial Mod- ulation (SM). It uses only one radio frequency (RF) chain that reduces the hardware complexity and cost of the system. The concept of SM is to transmit the data information using modulation constellation and spatial constellation. It increases the spectral efficiency by keeping only one an- tenna active per every symbol period. Spatial Multiplexing (SMX) uses equal number of RF chains with transmit antennas that increases the hardware complexity and cost of the system. SM is free from Inter Channel Interference (ICI) and Inter Symbol Interference (ISI). Generalised Spatial Modulation (GSM) and Multiple Active Spatial Modulation (MASM) techniques were developed to increase the spectral efficiency of SM by increasing the number of RF chains. In GSM, the same modulation symbol transmits on different antennas hence, it avoids ISI. In MASM, multiple symbols are transmitted on different antenna con guration. A modi ed version of SM technique called Quadrature Spatial Modulation (QSM) uses both in-phase and quadrature dimensions to transmit the data symbol in one time instant. Hence, QSM enhance the spectral efficiency over SM. Recently, Generalised QSM (GQSM) scheme was developed to increase spectral efficiency by grouping the transmit antennas according to QSM principle. We propose a modi ed Generalised QSM (mGQSM) scheme without antenna grouping and we use multiple RF chains to enhance the spectral efficiency. The proposed scheme provides ex- tra one bit per channel use (bpcu) spectral efficiency over GQSM scheme with the constraint of flog2 Nt Nrf g 0:5, where f g denotes the fractional part of the decimal value, Nt denotes number of transmit antennas, and Nrf denotes number of RF chains. In mGQSM system, multiple data symbols are divided into real and imaginary parts and these parts are transmitted as in-phase and quadrature components by selecting any possible antenna activation patterns available in mGQSM, resulting in the choice of antenna activation patterns being doubled in mGQSM compared to GQSM which yields the extra one bpcu spectral efficiency over GQSM. Using the ML detection algorithm, we study the performance via numerical simulations using half code rate convolutional encoder at the transmitter and Viterbi decoding algorithm at the receiver to estimate the transmitted bits. We compute the computational complexity of ML- decoding in terms of real valued multiplications and introduce a variant of mGQSM called Reduced Codebook mGQSM (RC-mGQSM) to reduce the complexity by decreasing the spectral efficiency. In summary, a novel scheme mGQSM is proposed which improves the spectral efficiency of known scheme, GQSM by one bpcu.

Considerando os avanços tecnológicos das últimas décadas, espera-se que a próxima geração de comunicações sem fios siga a tendência de um aumento significativo da robustez do sistema, da eficiência espectral (SE) e da eficiência energética (EE). Atualmente na era do pós-5G, os esquemas de "Multiple Input, Multiple Output" (MIMO) baseados em modulações espaciais generalizadas (GSM) bem como noutras modulações de índices (IM), têm sido amplamente considerados como potenciais técnicas candidatas para as redes sem fios. Esta dissertação tem como objetivo desenhar e estudar um sistema MIMO para comunicações multiutilizador integrando símbolos GSM e símbolos de modulação de índices generalizada no espaço-frequência (GSFIM). Numa primeira parte estuda-se um sistema MIMO multiutilizador, em que uma estação base (BS) transmite símbolos GSM pré-codificados para vários recetores. Na abordagem GSM adotada, múltiplas antenas transmitem simultaneamente diferentes símbolos M-QAM de alto nível, até M =1024. O pré-codificador é desenvolvido de modo a remover interferências entre utilizadores enquanto um algoritmo iterativo baseado no "alternating direction method of multipliers" (ADMM) é aplicado no recetor para realizar a deteção GSM de um único utilizador. Os resultados mostram que a abordagem GSM MU-MIMO apresentada é capaz de explorar eficazmente um grande número de antenas de transmissão implantadas no transmissor e também proporcionar ganhos de desempenho sobre esquemas convencionais MU-MIMO com eficiências espectrais idênticas. Numa segunda parte, introduz-se uma nova dimensão (para além do espaço), a frequência. Estuda-se assim o comportamento dos recetores MMSE e OB-MMSE, num sistema MIMO baseado em GSFIM. Os resultados mostram que o sistema GSFIM MUMIMO explora de forma competente as comunicações com grande número de antenas/sub-portadoras, apresentando melhores desempenhos quando usada com um recetor OB-MMSE.<br>Considering the technological advances of the last decades, the next generation of wireless communications is expected to follow the trend of a significant increase in system robustness, spectral efficiency (SE) and energy efficiency (EE). Today in the post5G era, Multiple Input, Multiple Output (MIMO) schemes based on generalised spatial modulations (GSM) as well as other index modulations (IM) have been widely considered as potential candidate techniques for wireless networks. This dissertation aims to design and study a MIMO system for multi-user communications integrating GSM symbols and generalised space-frequency index modulation (GSFIM) symbols. In a first part, a multi-user MIMO system is studied, in which a base station (BS) transmits pre-coded GSM symbols to several receivers. In the GSM approach adopted, multiple antennas transmit different high-level M-QAM symbols simultaneously, up to M =1024. The precoder is designed to remove interference between users while an iterative algorithm based on the alternating direction method of multipliers (ADMM) is applied to the receiver to perform single user GSM detection. The results show that the GSM MU-MIMO approach presented is capable of effectively exploiting a large number of transmission antennas deployed on the transmitter and also provides desempenho gains over conventional MU-MIMO schemes with identical spectral efficiencies. In a second part, a new dimension (beyond space) is introduced, frequency. The behaviour of MMSE and OB-MMSE receivers in a GSFIM-based MIMO system is thus studied. The results show that the GSFIM MU-MIMO system competently exploits communications with large numbers of antennas/sub-carriers and performs better when used with an OB-MMSE receiver.

碩士<br>國立中山大學<br>通訊工程研究所<br>106<br>Spatial-Multiplexing aided Generalized Spatial Modulation (SMx-GSM) is essentially a combination of Vertical Bell Labs Layered Space-Time and Generalized Spatial Modulation (GSM) to achieve a high transmission rate technology. In transmitter, the transmit antennas are divided into several groups and each group use GSM technique. Therefore, we don’t need a lot of Radio Frequency chain to transmit signal and will not cause serious inter-channel interference. Compare to the conventional GSM, we can implement high transmission rate system by using the characteristics of SMx-GSM symbols at receiver. In this thesis, we explain a low-complexity detector for SMx-GSM. We use tree search algorithm and utilize a low-complexity cost function to find a set of transmit antenna combinations with maximum a posteriori probability for optimal detection. From the results of the simulation, the detection complexity can be greatly reduced, that make high-rate system feasible.

Traditionally, symbols chosen from complex modulation alphabets such as QAM and PSK are used to convey information bits, and complex fades introduced by the channel are viewed as detrimental effects that cause amplitude and phase distortion to the transmitted symbols. An alternative and interesting approach is to consider the complex channel fade coefficients themselves to constitute a modulation alphabet (referred to as `channel alphabet'). An example of this approach is a recently proposed `media-based modulation (MBM)' scheme, which uses digitally controllable parasitic elements (called as radio frequency mirrors) near the transmit antenna(s) to create the channel alphabet. Each radio frequency (RF) mirror can be either ON or OFF. A mirror allows the incident RF signal to pass through it transparently when it is ON, and reflects back the incident RF signal when it is OFF. The ON/OFF status of the mirrors is called as `mirror activation pattern (MAP)'. The channel alphabet needs to be known only at the receiver and not at the transmitter. MBM has been shown to achieve significant performance gains compared to conventional modulation schemes. In this thesis, we investigate the performance of MBM in various scenarios like transmission with feedback, differential transmission, imperfect channel state information, full-duplex communications, and cooperative relaying. The contributions in this thesis are three-fold. In the first part, we investigate the performance of some interesting physical layer techniques when applied to MBM. First, we combine MBM with generalized spatial modulation (GSM), and investigate its performance. Next, we study the performance of feedback based mirror activation pattern (MAP) selection (analogous to transmit antenna selection in multi-antenna systems), and phase compensation and constellation rotation (PC-CR) techniques in MBM. We also analyze the diversity orders achieved by the ED-based MAP selection scheme and the PC-CR scheme. In the second part, we deal with channel estimation aspects in MBM. First, we present a differential MBM (DMBM) scheme which does not require estimation of channel modulation alphabet at the receiver for detection. We also propose a low-complexity maximum-likelihood (ML) detection algorithm for DMBM. Next, we analyze the effect of imperfect channel estimation on the bit error performance of MBM. We analyze the performance for two types of detectors, namely, i) the commonly studied mismatched detector, and ii) the true ML detector that maximizes the likelihood by taking the statistics of the channel estimate into account. In the final part, we investigate the performance of full-duplex (FD) communication using MBM, and compare it with that of FD with conventional modulation schemes. First, we investigate the FD communication using MBM and DMBM in a point-to-point setting, and present detectors for signal detection. Next, we analyze the performance of a two-hop three-node FD relay network, where the source and relay nodes transmit using MBM. The relay uses decode-and-forward (DF) relaying protocol. Next, we investigate the performance of MBM in a two-way relaying network, where two FD nodes exchange information with the help of a FD relay node using DF protocol.

碩士<br>國立中山大學<br>通訊工程研究所<br>103<br>The generalized spatial modulation (GSM) is developed as a promising modulation scheme which effectively compromises the hardware complexity and the spectral efficiency in the multiple-input and multiple-output (MIMO) systems. In this paper, we further propose a precoding design for improving the performance of GSM-MIMO systems. We first formulate precoding design as an optimization of which the worst-case minimum free-distance can be maximized. As well know, the free-distance is the critical metric in evaluating the performance of the maximum likelihood (ML) detection. To facilitate the derivation, we then decompose the precoder design into the power allocation times a structured precoder for each antenna group. With the decomposition, we can easily derive a closed-form solution for the precoder design, which can greatly reduce the computational complexity and is suitable for the real-time implementation. Simulation results show the superiority of our design measured by both the BER and computational complexity compared with the existing methods.

碩士<br>國立清華大學<br>通訊工程研究所<br>103<br>The concept of Generalized Spatial modulation (GSM) has been proposed as a promising architecture for low complexity massive MIMO systems. The GSM systems activates only small number of transmit antennas at a symbol time which simply the complexity in implementation. Different selection of the activating antennas patterns change the average symbol error rate (SER) performance, however the optimal selection of the activating antenna patterns is an NP hard problem due to the complicated connection in the universe of antenna patterns set. Through [1] has proposed a suboptimal design criterion for the codeword construction problem, it does not proposed the corresponding algorithms to realize the criterion. Even the suboptimal algorithm for the GSM codeword construction problem has not been proposed yet. Motivating by the above reasons, in this thesis we propose two GSM codeword construction criterions in the sense of minimizing the average symbol error rate (SER). We also design the corresponding systematic greedy-like algorithms for the proposed criterions and for the criterion proposed by [1]. At the last of the thesis we show the numerical results for the proposed codeword construction algorithms and we verify the performance of the proposed algorithms are indeed better than the algorithm whose design criterion is proposed by [1] and also better than the random selection method.

碩士<br>國立清華大學<br>電機工程學系<br>104<br>Massive multiple-input multiple-output system, has many advantages for wireless communication system, has higher data rate and accommodate more users. Due to generalized spatial modulation can effectively reduce hardware complexity and improve the spectral efficiency of multiple-input multiple-output system, it is a modulation method whitch combines the combination of transmit antennas and digital modulation as a transmission codeword and has been widely discussed in recent years. Nowadays, there are a lot of discussions about the hard-decision detections of generalized spatial modulation. The complexity of inverse matrix operations is high computational. Under these circumstances, we propose a detection method that is similar to tree search whitch has lower computation and present the soft-decision detections whitch is applicable to Low-density parity-check(LDPC) code. In view of the results, we have a tight performance loss compared to maximum a posteriori(MAP) detection.