This paper investigates the implementation scenario of Space Division Multiple Access(SDMA) which is a notable application of Multiple Input Multiple Output(MIMO) system. SDMA is one of the most promising techniques aiming at solving the capacity problem of wireless communication systems and achieving higher spectral efficiency, depending on multiplexing signals based on their spatial signature. This paper presents of combining SDMA combined with the Orthogonal Frequency Division Multiplexing (OFDM). Various SDMA techniques are investigated including linear detection schemes, minimum mean square error, ordered successive cancellation, and maximum likelihood methods. Promising results are obtained to enhance spectral efficiency on the expense of computational complexity which needs to be addressed.
This paper considers codebook-based precoding for Space Shift Keying (SSK) modulation MIMO system. Codebook-based precoding avoids the necessity for full knowledge of Channel State Information (CSI) at the transmitter and alleviates the complexity of generating a CSI-optimized precoder. The receiver selects the codeword that maximizes the Minimum Euclidean Distance (MED) of the received constellation and feeds back its index to the transmitter. In this paper, we first develop a new accurate closed-form Bit Error Rate (BER) for SSK without precoding. Then, we investigate several phase-rotation codebooks with quantized set of phases and systematic structure. Namely, we investigate the Full-Combination, Walsh-Hadamard, Quasi-Orthogonal Sequences, and Orthogonal Array Testing codebooks. In addition, since the size of the Full-Combination codebook may be large, we develop an iterative search method for fast selection of its best codeword. The proposed codebooks significantly improve the BER performance in Rayleigh and Nakagami fading channels, even at high spatial correlation among transmit antennas and CSI estimation error. Moreover, we show that only four phases {+1, + , −1, − } are sufficient and further phase granularity does yield significant gain. This avoids hardware multiplication during searching the codebook and applying the codeword.
In this research, a modified fractional order proportional integral derivate (FOPID) control method is proposed for the photovoltaic (PV) and thermoelectric generator (TEG) combined hybrid renewable energy system. The faster tracking and steady-state output are aimed at the suggested maximum power point tracking (MPPT) control technique. The derivative order number (µ) value in the improved FOPID (also known as PI λ D µ ) control structure will be dynamically updated utilizing the value of change in PV array voltage output. During the transient, the value of µ is changeable; it's one at the start and after reaching the maximum power point (MPP), allowing for strong tracking characteristics. TEG will use the freely available waste thermal energy created surrounding the PV array for additional power generation, increasing the system's energy conversion efficiency. A high-gain DC-DC converter circuit is included in the system to maintain a high amplitude DC input voltage to the inverter circuit. The proposed approach's performance was investigated using an extensive MATLAB software simulation and validated by comparing findings with the perturbation and observation (P&O) type MPPT control method. The study results demonstrate that the FOPID controller-based MPPT control outperforms the P&O method in harvesting the maximum power achievable from the PV-TEG hybrid source. There is also a better control action and a faster response.
Robust multi-user detection (MUD) methods based on space division multiple access (SDMA) techniques are essential to efficiently exploit the electromagnetic spectrum. In this paper, an adaptive Genetic Algorithm-based tool for SDMA-OFDM Systems (GASOS) is developed to improve the performance and computational complexity in cases of fully-loaded and overloaded multi-user scenarios. The data flow in GASOS is appropriate in pipelining and parallelization to reduce operational time. A new GASOS-based MUD hardware design for SDMA-OFDM systems is proposed using FPGA architecture. The design details are presented together with their planned operational modules. Resource utilization is optimized, and the total number of clock cycles required is found to be 15 initially, in addition to one clock cycle per member of algorithm population. A clock frequency of 100 MHz is used and implementation is carried out on Xilinx Ò Virtex-6 FPGA, built in the development platform ML605 edition with JTAG Hardware Co-simulation. According to the results obtained from the developed algorithm and implementation tools, a high number of users can be physically possible and provided with support. Real-time based implementation of MUD systems has the potential to play a major role in next-generation communication systems.
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