Exploiting Amplitude Control in Intelligent Reflecting Surface Aided Wireless Communication with Imperfect CSI

Intelligent reflecting surface (IRS) is a promising new paradigm to achieve high spectral and energy efficiency for future wireless networks by reconfiguring the wireless signal propagation via passive reflection. To reap the potential gains of IRS, channel state information (CSI) is essential, whereas channel estimation errors are inevitable in practice due to limited channel training resources. In this paper, in order to optimize the performance of IRS-aided multiuser systems with imperfect CSI, we propose to jointly design the active transmit precoding at the access point (AP) and passive reflection coefficients of IRS, each consisting of not only the conventional phase shift and also the newly exploited amplitude variation. First, the achievable rate of each user is derived assuming a practical IRS channel estimation method, which shows that the interference due to CSI errors is intricately related to the AP transmit precoders, the channel training power and the IRS reflection coefficients during both channel training and data transmission. Then, for the single-user case, by combining the benefits of the penalty method, Dinkelbach method and block successive upper-bound minimization (BSUM) method, a new penalized Dinkelbach-BSUM algorithm is proposed to optimize the IRS reflection coefficients for maximizing the achievable data transmission rate subjected to CSI errors; while for the multiuser case, a new penalty dual decomposition (PDD)-based algorithm is proposed to maximize the users' weighted sum-rate. Simulation results are presented to validate the effectiveness of our proposed algorithms as compared to benchmark schemes. In particular, useful insights are drawn to characterize the effect of IRS reflection amplitude control (with/without the conventional phase shift) on the system performance under imperfect CSI.Comment: 15 pages, 10 figures, accepted by IEEE Transactions on Communication

Synaesthesia in Chinese: A corpus-based study on gustatory adjectives in Mandarin

This study adopted a corpus-based approach to examine the synaesthetic metaphors of gustatory adjectives in Mandarin. Based on the distribution of synaesthetic uses in the corpus, we found that: (1) the synaesthetic metaphors of Mandarin gustatory adjectives exhibited directionality; (2) the directionality of Mandarin synaesthetic gustatory adjectives showed both commonality and specificity when compared with the attested directionality of gustatory adjectives in English, which calls for a closer re-examination of the claim of cross-lingual universality of synaesthetic tendencies; and (3) the distribution and directionality of Mandarin synaesthetic gustatory adjectives could not be predicted by a single hypothesis, such as the embodiment-driven approach or the biological association-driven approach. Thus, linguistic synaesthesia was constrained by both the embodiment principle and the biological association mechanism

A study on the agglomeration characteristics of the scallop aquaculture industry in China

Scallops are economically important shellfish widely cultured in China. In this study, the agglomeration characteristics of the scallop aquaculture industry in Chinese coastal provinces were explored based on data from the China Fishery Statistical Yearbook from 2012 to 2020 and the comparative advantage and concentration level of the scallop breeding industry. The data were analyzed using the comprehensive relative advantage index, location entropy, and industrial concentration degree method. Two main results revealed that Hebei Province had the highest comparative advantage in terms of efficiency, followed by Fujian, Guangdong, Shandong, Guangxi, Liaoning, and Zhejiang Provinces. Hebei Province had the highest comparative advantage in scale, followed by Liaoning, Shandong, Hainan, Guangdong, Guangxi, Fujian, and Zhejiang Provinces. Additionally, the scallop cultivation industry in Hebei, Shandong, and Liaoning Provinces showed a high concentration, and the proportion of scallop production in the national production (CR4) in the three provinces, as well as in Guangdong, accounted for more than 99% year-round. Overall, Hebei, Shandong, and Liaoning Provinces had a comparative advantage in scale, comprehensive comparative advantage, and industrial agglomeration

Auditory Synaesthesia and Near Synonyms: A Corpus-Based Analysis of sheng1 and yin1 in Mandarin Chinese

This paper explores the nature of linguistic synaesthesia in the auditory domain through a corpus-based lexical semantic study of near synonyms. It has been established that the near synonyms 聲 sheng “sound ” and 音 yin “sound ” in Mandarin Chinese have different semantic functions in representing auditory production and auditory perception respec-tively. Thus, our study is devoted to test-ing whether linguistic synaesthesia is sensi-tive to this semantic dichotomy of cognition in particular, and to examining the relation-ship between linguistic synaesthesia and cog-nitive modelling in general. Based on the cor-pus, we find that the near synonyms exhibit both similarities and differences on synaesthe-sia. The similarities lie in that both 聲 and音 are productive recipients of synaesthetic trans-fers, and vision acts as the source domain most frequently. Besides, the differences exist in se-lective constraints for 聲 and 音 with synaes-thetic modifiers as well as syntactic functions of the whole combinations. We propose that the similarities can be explained by the cogni-tive characteristics of the sound, while the dif-ferences are determined by the influence of the semantic dichotomy of production/perception on synaesthesia. Therefore, linguistic synaes-thesia is not a random association, but can be motivated and predicted by cognition.

Intelligent Reflecting Surface Enhanced Wireless Network: Two-timescale Beamforming Optimization

Intelligent reflecting surface (IRS) has drawn a lot of attention recently as a promising new solution to achieve high spectral and energy efficiency for future wireless networks. By utilizing massive low-cost passive reflecting elements, the wireless propagation environment becomes controllable and thus can be made favorable for improving the communication performance. Prior works on IRS mainly rely on the instantaneous channel state information (I-CSI), which, however, is practically difficult to obtain for IRS-associated links due to its passive operation and large number of elements. To overcome this difficulty, we propose in this paper a new two-timescale (TTS) transmission protocol to maximize the achievable average sum-rate for an IRS-aided multiuser system under the general correlated Rician channel model. Specifically, the passive IRS phase-shifts are first optimized based on the statistical CSI (S-CSI) of all links, which varies much slowly as compared to their I-CSI, while the transmit beamforming/precoding vectors at the access point (AP) are then designed to cater to the I-CSI of the users' effective channels with the optimized IRS phase-shifts, thus significantly reducing the channel training overhead and passive beamforming complexity over the existing schemes based on the I-CSI of all channels. For the single-user case, a novel penalty dual decomposition (PDD)-based algorithm is proposed, where the IRS phase-shifts are updated in parallel to reduce the computational time. For the multiuser case, we propose a general TTS optimization algorithm by constructing a quadratic surrogate of the objective function, which cannot be explicitly expressed in closed-form. Simulation results are presented to validate the effectiveness of our proposed algorithms and evaluate the impact of S-CSI and channel correlation on the system performance.Comment: 15 pages, 12 figures, accepted for publication in IEEE Transactions on Wireless Communication