Differential spatial modulation (DSM) involves the transmission of information through a combination of phase-modulated symbols and transmit antenna index. For efficient use of the wireless system resources, the ampli...
详细信息
Differential spatial modulation (DSM) involves the transmission of information through a combination of phase-modulated symbols and transmit antenna index. For efficient use of the wireless system resources, the amplitude information is also utilised as a part of the transmitted data in amplitude-phase shift keying-DSM (APSK-DSM). Here some of the information bits get encoded as differential amplitude in each of the transmit antennas, whenever they are activated resulting in better bandwidth efficiency than conventional DSM. However, prevailing detectors for APSK-DSM have high computational complexity. In this work, the authors proposed a low complexity detector for APSK-based DSM schemes using compressive sensing and an l2-norm minimisation for detecting the differential amplitude. To decode this amplitude information, the authors have formulated a column by column decomposition of the received symbol in terms of the amplitude- and phase-modulated symbols received from each transmit antenna. The error performance of the proposed detector is nearly identical to that of existing APSK-based DSM receivers, which use maximum-likelihood detection but with much lower computational complexity than the latter.
Among various index modulation technology, adaptive orthogonal frequency division multiplexing with index modulation (A-OFDM-IM) improves reliability by solving the problem of deep fading. However, the maximal likelih...
详细信息
Among various index modulation technology, adaptive orthogonal frequency division multiplexing with index modulation (A-OFDM-IM) improves reliability by solving the problem of deep fading. However, the maximal likelihood (ML) detector of A-OFDM-IM has high complexity by simultaneously performing active subcarrier detection and quadrature amplitude modulation (QAM) symbol demodulation. A simpler type of ML detector can be applied since the A-OFDM-IM has independent active states of each subcarrier and uses a single QAM constellation. In this paper, we propose two low-complexitydetectors for the A-OFDM-IM. The proposed detectors have a two-stage receiving process, active subcarrier detection, and QAM demodulation. In active subcarrier detection, the presence or absence of the QAM symbol is more important than its information. Therefore we derive the thresholds using the absolute value of the in-phase and quadrature components of the received signal in the frequency domain. Using the absolute value, the distribution of noise added to inactive subcarrier is half normal. This is different from noise distribution of the ML detector, and the proposed detectors select the threshold considering the corresponding noise distribution. The first proposed detector uses a threshold derived by the ML estimation method. The second detector estimates the active subcarriers via a support vector machine. The proposed detectors have lower complexity than the ML detector because of the divided receiving process. Moreover, the theoretical analysis and simulation results show that the proposed detectors have better reliability than the ML detector due to different noise distribution and thresholds.
Differential spatial modulation (DSM) is a multi-antenna technique that does not require channel state information (CSI). However, DSM has a deficiency of low spectral efficiency (SE). In this paper, a differential sp...
详细信息
Differential spatial modulation (DSM) is a multi-antenna technique that does not require channel state information (CSI). However, DSM has a deficiency of low spectral efficiency (SE). In this paper, a differential space-time media-based modulation (DSTMBM) system is proposed. The DSTMBM system equips radio frequency (RF) mirrors to transmit additional bits, which leads to an improvement of SE. Simulation results show that the bit error rate (BER) performance of DSTMBM is about 4 dB better than that of DSM under the same parameters. For low-complexity implementation, a genetic algorithm aided compressed sensing (GA-CS) detector is tailored to the DSTMBM system. Compared with the state-of-the-art low-complexitydetector with the best performance in differential systems, the GA-CS detector achieves a complexity reduction of 3 orders of magnitude when the transmit matrix dimensions are 8 x 8, at the cost of only around 1 dB in terms of BER performance. Furthermore, the complexity of GA-CS detector does not grow exponentially with the matrix dimension.
Orthogonal frequency division multiplexing is a multicarrier digital modulation technique that is extensively used in modern wireless communication systems. Index Modulation combined with orthogonal frequency division...
详细信息
ISBN:
(纸本)9781728188676
Orthogonal frequency division multiplexing is a multicarrier digital modulation technique that is extensively used in modern wireless communication systems. Index Modulation combined with orthogonal frequency division multiplexing lead to improved spectral efficiency. Dual mode orthogonal frequency division multiplexing with index modulation aims at increasing spectral efficiency even further. The improved spectral efficiency comes at a cost of increased signal detection complexity at receiver side. Here we propose yet another index modulation aided dual mode orthogonal frequency division multiplexing technique where the two modes can be selected from a set of four modes or constellations. By doing this we increased the proportion of index bits compared to data bits, eventually leading to an increase in spectral efficiency. This paper describes in detail our proposed method, the accompanying transmission and receiver detection technique. We also illustrate the spectral and energy efficiency of proposed technique and compare its performance with its nearest counterparts.
In large-scale multiple-input multiple-output (LS-MIMO) systems, by exploiting hundreds of antennas at the base station, spectral efficiency, power efficiency, and link reliability can be enhanced significantly. Howev...
详细信息
ISBN:
(纸本)9781538681107
In large-scale multiple-input multiple-output (LS-MIMO) systems, by exploiting hundreds of antennas at the base station, spectral efficiency, power efficiency, and link reliability can be enhanced significantly. However, by increasing the number of antennas, the computational complexity of the detectors makes the hardware implementation intractable, and therefore, LS-MIMO systems require sub-optimal lowcomplexity detection algorithms. In this paper, two novel approaches for improving factor graph-based belief propagation with Gaussian approximation of interference (FG-BP-GAI) algorithm is proposed to reduce the computational complexity of the belief propagation (BP) based receiver without bit error rate (BER) degradation. More specifically, two novel techniques, namely odd Taylor series and odd least square, are proposed to approximate the a posteriori probability in the FG-BP-GAI policy with few polynomial terms of low degree. In the simulation results, the performance of our proposed algorithms are assessed and it is shown that our proposed improved FG-BP-GAI policies can achieve lower computational complexity compared with the other approaches in the literature like MRF-BP algorithm without BER degradation.
暂无评论