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China Communications
Journal Prestige (SJR): 0.314
Citation Impact (citeScore): 2
Number of Followers: 8  
 
  Full-text available via subscription Subscription journal
ISSN (Online) 1673-5447
Published by IEEE Homepage  [228 journals]
  • Guest editorial: Channel measurements and models for 6G

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      Authors: Jianhua Zhang;Bo Ai;Chengxiang Wang;Xiang Cheng;Mansoor Shafi;Wei Fan;
      Abstract: In the early stage of 6G research, carrying out research on channel measurements and models is one of the fundamental and prerequisite works, as well as full of the challenges. Driven by the demand for multiple frequency bands, versatile scenarios, and various new technologies in the future, 6G channels are expanding in multiple dimensions such as the space-time-frequency domains. Those all make 6G channel measurement and modeling research face a series of new challenges, e.g., non-stationarity in multiple dimensions, the obvious increase in modeling complexity, and changes in theoretical premises and assumptions. It is therefore clear that more efforts are needed to understand propagation characteristics, especially in the new scenes and applications, and to develop a new paradigm for 6G channel modeling.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Back cover

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      Abstract: Presents the back cover for this issue of the publication.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Environment information-based channel prediction method assisted by graph
           neural network

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      Authors: Yutong Sun;Jianhua Zhang;Yuxiang Zhang;Li Yu;Qixing Wang;Guangyi Liu;
      Pages: 1 - 15
      Abstract: Recently, whether the channel prediction can be achieved in diverse communication scenarios by directly utilizing the environment information gained lots of attention due to the environment impacting the propagation characteristics of the wireless channel. This paper presents an environment information-based channel prediction (EICP) method for connecting the environment with the channel assisted by the graph neural networks (GNN). Firstly, the effective scatterers (ESs) producing paths and the primary scatterers (PSs) generating single propagation paths are detected by building the scatterer-centered communication environment graphs (SC-CEGs), which can simultaneously preserve the structure information and highlight the pending scatterer. The GNN-based classification model is implemented to distinguish ESs and PSs from other scatterers. Secondly, large-scale parameters (LSP) and small-scale parameters (SSP) are predicted by employing the GNNs with multi-target architecture and the graphs of detected ESs and PSs. Simulation results show that the average normalized mean squared error (NMSE) of LSP and SSP predictions are 0.12 and 0.008, which outperforms the methods of linear data learning.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Multi-scenario millimeter wave wireless channel measurements and sparsity
           analysis

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      Authors: Hang Mi;Bo Ai;Ruisi He;Xin Zhou;Zhangfeng Ma;Mi Yang;Zhangdui Zhong;Ning Wang;
      Pages: 16 - 31
      Abstract: Wireless channel characteristics have significant impacts on channel modeling, estimation, and communication performance. While the channel sparsity is an important characteristic of wireless channels. Utilizing the sparse nature of wireless channels can reduce the complexity of channel modeling and estimation, and improve system design and performance analysis. Compared with the traditional sub-6 GHz channel, millimeter wave (mmWave) channel has been considered to be more sparse in existing researches. However, most research only assume that the mmWave channel is sparse, without providing quantitative analysis and evaluation. Therefore, this paper evaluates the sparsity of mmWave channels based on mmWave channel measurements. A vector network analyzer (VNA)-based mmWave channel sounder is developed to measure the channel at 28 GHz, and multi-scenario channel measurements are conducted. The Gini index, Rician K factor and root-mean-square (RMS) delay spread are used to measure channel sparsity. Then, the key factors affecting mmWave channel sparsity are explored. It is found that antenna steering direction and scattering environment will affect the sparsity of mmWave channel. In addition, the impact of channel sparsity on channel eigenvalue and capacity is evaluated and analyzed.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • AG channel measurements and characteristics analysis in hilly scenarios
           for 6G UAV communications

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      Authors: Chongyang Yu;Yu Liu;Hengtai Chang;Jingfan Zhang;Mengjiao Zhang;Peter Poechmueller;Chengxiang Wang;
      Pages: 32 - 46
      Abstract: As an important part of sixth generation (6G) integrated space-air-ground-sea networks, unmanned aerial vehicle (UAV) communications have aroused great attention and one of its typical application scenarios is the hilly environments. The related UAV air-ground (AG) channel characteristics analysis is crucial for system design and network evaluation of future UAV communications in hilly scenarios. In this paper, a recently conducted channel measurements campaign in a hilly scenario is presented, which is conducted at the center frequencies of 2.585 GHz and 3.5 GHz for different flight trajectories. Based on the measurement data, some key channel characteristics are analyzed, including path loss (PL), shadow fading (SF), Rician K-factor, root mean square (RMS) delay spread (DS), and temporal auto-correlation function (ACF). Finally, the comparison of typical channel characteristics under circular and straight trajectories is given. The related results can provide a theoretical reference for constructing future UAV communication system in hilly scenarios.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Long-range VNA-based channel sounder: Design and measurement validation at
           MmWave and sub-THz frequency bands

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      Authors: Mikkel Bengtson;Yejian Lyu;Wei Fan;
      Pages: 47 - 59
      Abstract: With the increasing demand for high bandwidth wireless communication systems, and with a congested spectrum in the sub-6 GHz frequency bands, researchers have been looking into exploration of millimeter wave (mmWave) and sub-terahertz (sub-THz) frequency bands. Channel modeling is essential for system design and performance evaluation of new wireless communication systems. Accurate channel modeling relies on reliable measured channel data, which is collected by high-fidelity channel sounders. Furthermore, it is of importance to understand to which extent channel parameters are frequency dependent in typical deployment scenario (including both indoor short-range and outdoor long-range scenarios). To achieve this purpose, this paper presents a state-of-art long-range 28 GHz and 300 GHz VNA-based channel sounder using optical cable solutions, which can support a measurement range up to 300 m and 600 m in principle, respectively. The design, development and validation of the long-range channel sounders at mmWave and sub-THz bands are reported, with a focus on their system principle, link budget, and back-to-back measurements. Furthermore, a measurement campaign in an indoor corridor is performed using the developed 300 GHz system and 28 GHz channel sounding systems. Both measured channels at the 28 GHz and 300 GHz channels are shown to be highly sparse and specular. A higher number of Multi Path Components (MPC) are observed for the 28 GHz system, while the same main MPC are observed for both systems.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • A novel millimeter-wave channel measurement platform for 6G intelligent
           railway scenarios

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      Authors: Dan Fei;Chen Chen;Peng Zheng;Dongsheng Zhang;Jingya Yang;Haoran Chen;Bo Ai;
      Pages: 60 - 73
      Abstract: This paper presented a novel millimeter-wave channel measurement platform for the 6G intelligent railway. This platform used phased array antenna with 64 elements and can support instant bandwidth up to 1 GHz. Combined with improved multi-tone sounding signals, the platform can enhance dynamic measurement capability in high-speed railway scenarios. We performed calibration works about frequency flatness, frequency offset and proved platform reliability with channel emulator based closed-loop verification. We also carried out field trials in high-speed railway carriage scenarios. Based on measurement results, we extracted channel characteristic parameters of path loss, power delay profile and delay spread to further verify the field measurement performance of the platform.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • A geometry-based stochastic scattering channel model for V2V
           communications in dense urban street environments

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      Authors: Jie Zhou;Zhikang Lyu;Sujie Wu;Hong Luo;Ting Liu;Genfu Shao;Shigenobu Sasaki;
      Pages: 74 - 87
      Abstract: In this paper, we propose a stochastic channel model in three-dimensional (3D) space for multiple input multiple output (MIMO) vehicle-to-vehicle (V2V) communications in dense urban environments. The movement of the mobile transmitter and mobile receiver results in the V2V channel model behave temporal non-stationarity. Therefore, the time-varying parameters of the propagation paths and angles are derived to characterize such property. Using this channel model, we investigate the propagation characteristics of V2V channels in terms of the road section and moving time/directions/speeds of the transmitter and receiver. Numerical results show that the theoretical results of the propagation characteristics of the V2V channel model are very close to those of the simulation ones, which show that the proposed channel model is suitable for depicting the V2V communications in dense urban scenarios.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • UWB channel modeling and simulation with continuous frequency response

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      Authors: Kai Mao;Qiuming Zhu;Xijuan Ye;Ruirui Feng;Fuqiao Duan;Yang Miao;Maozhong Song;
      Pages: 88 - 98
      Abstract: Ultra-wideband (UWB) technology is a prospective technology for high-rate transmission and accurate localization in the future communication systems. State-of-art channel modeling approaches usually divide the UWB channel into several sub-band channels and model them independently. By considering frequency-dependent channel parameters, a novel analytical UWB channel model with continuous frequency response is proposed. The composite effect of all frequency components within the UWB channel on the channel impulse response (CIR) of delay domain is derived based on the continuous channel transfer function (CTF) of frequency domain. On this basis, a closed-form simulation model for UWB channels and geometry-based parameter calculation method are developed, which can guarantee the continuity of channel characteristics on the frequency domain and greatly reduce the simulation complexity. Finally, the proposed method is applied to generate UWB channel with 2 GHz bandwidth at sub-6GHz and millimeter wave (mmWave) bands, respectively. The channel measurements are also carried out to validate the proposed method. The simulated CIR and power gain are shown to be in good agreement with the measurement data. Moreover, the comparison results of power gain and Doppler power spectral density (DPSD) show that the proposed UWB channel model achieves a good balance between the simulation accuracy and efficiency.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • A fuzzy clustering algorithm based on multipath component trajectory for
           millimeter wave radio channels

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      Authors: Fei Du;Yu Zhang;Qingliang Li;Xinyue Zhang;Bo Zhu;Zihao Fu;Suiyan Geng;Xiongwen Zhao;
      Pages: 99 - 111
      Abstract: Time-varying channel modeling plays an important role for many applications in time-variant scenarios, while most clustering algorithms focus on static channels and cannot accurately model the channel time-evolution properties. In this paper, a fuzzy clustering algorithm based on multipath component (MPC) trajectory is proposed. Firstly, both the distance and velocity similarities of the MPCs in different snapshots are taken into account to track the MPC trajectory, in which the fuzzy scheme and a kernel function are used to calculate the distance and velocity similarities, respectively. Secondly, a fuzzy MPC trajectory clustering algorithm is proposed to cluster the MPCs in multiple snapshots. The MPCs in a snapshot are clustered according to the membership, which is defined as the probability that a MPC belongs to different clusters. Finally, time-varying channels at 28 GHz are simulated to validate the performance of our proposed algorithm. The results show that our proposed algorithm is able to accurately identify the clusters in time-varying channels compared with the existing clustering algorithms.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • V2V channel modeling at 5.2 GHz for highway environment

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      Authors: Suying Jiang;Wei Wang;Ibrahim Rashdan;
      Pages: 112 - 128
      Abstract: To design and evaluate vehicle-to-vehicle (V2V) communication systems in intelligent transportation system (ITS), it is important to understand the propagation mechanisms and channel models of V2V channels. This paper aims to analyze the channel models at 5.2 GHz for the highway environment in obstructed line-of-sight (OLoS) and line-of-sight (LoS) scenarios, particularly the vehicle connectivity probability derivation based on the propagation model obtained from measurement. First, the path loss (PL), shadow fading (SF), narrowband K-factor, and small-scale amplitude fading are analyzed. Results showed that the received signal magnitude follows Rice and Weibull distribution in LoS and OLoS scenarios, respectively. Second, we develop simple and low-complexity tapped delay line (TDL) models with a 10 MHz bandwidth for LoS and OLoS scenarios; in addition, we investigate the wideband K-factor, the root mean square delay spread (RMS-DS), and delay-Doppler spectrum. Third, we derive the closed form connectivity probability between any two vehicles in the presence of Weibull fading channel, and analyze the effects of Weibull fading channel and traffic parameters on connectivity. It is found that Weibull fading parameter, transmit power and vehicle density have positive impact on connectivity probability, PL exponent has negative impact on connectivity probability.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Performance trade-off for integrated communication and data-assisted
           positioning in MIMO-OFDM system

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      Authors: Lincong Han;Rongke Liu;Zijie Wang;Qirui Liu;Qian Zhu;John S. Thompson;
      Pages: 129 - 147
      Abstract: Communication and positioning, the two pillars of mobile communication systems, are currently being integrated together. The development of communication technologies is the driving force of the positioning progress. In turn, the location information provided by positioning improves the communication performance in various ways. However, the competition of these two functions in terms of resource allocation is a critical issue hindering their integration. In this article, we investigate the trade-off for the integrated communication and data-assisted positioning in multiple-input multiple-output orthogonal frequency division multiplexing systems. A data-assisted positioning method is designed first, which uses both positioning reference signals (PRSs) and data signals for positioning. The positioning and communication performance are theoretically evaluated respectively, then combined to obtain an integrated performance metric. The trade-off is analyzed and the integrated performance is optimized considering the priority of different functions. Numerical simulations show that the data-assisted positioning can not only improve the positioning accuracy, but also reduce the PRS overhead. And the established integrated performance metric can identify the optimal performance and the corresponding resource allocation schemes.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Robust fingerprint localization based on massive MIMO systems

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      Authors: Xiaojun Wang;Yijie Ren;Weiguang Sun;Xiaoshu Chen;
      Pages: 148 - 159
      Abstract: Location-based services have become an important part of the daily life. Fingerprint localization has been put forward to overcome the shortcomings of the traditional positioning algorithms in indoor scenario and rich scattering environment. In this paper, a single-site multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system is modeled, from which an angle delay channel power matrix (ADCPM) is extracted. Considering the changing environment, auto encoders are used to generate new fingerprints based on ADCPM fingerprints to improve the robustness of the fingerprints. When the scattering environment has changed beyond a certain extent, the robustness will not be able to make up for the positioning error. Under this circumstance, an updating of the fingerprint database is imperative. A new fingerprint database updating algorithm which combines a new clustering method and an updating rule based on probability is proposed. Simulation results show the desirable performance of the proposed methods.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • A universal hybrid precoding scheme for massive MIMO communications

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      Authors: Yimeng Feng;Yi Jiang;Mahesh K. Varanasi;
      Pages: 160 - 178
      Abstract: Based on an analog radio frequency (RF) network, hybrid precoding (HPC) for massive MIMO can achieve very high spectral efficiencies with moderate hardware cost and power consumption. Despite the extensive research efforts in recent years, the practioners are still looking for HPCs that are efficient and easy-to-implement. In this paper, we present a new method termed as the universal hybrid precoding (UHP), which is nearly optimal, computationally efficient, and applicable to various types of RF network (thus, the name universal): the components of the network can be phase shifters (with finite or infinite resolutions), switches, or their combinations; the topology of the network can be fully-connected or partially-connected. Besides the standard UHP, we also propose a simplified version termed as sUHP to trade a negligible performance loss for much reduced computational complexity. The analysis shows that the computational complexity of the proposed UHP/sUHP is one to two orders of magnitude lower than the state-of-the-art methods. Simulation results verify the (near-) optimality of the proposed UHP scheme for various forms of the analog networks.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Non-orthogonal transmission for user and control plane split architecture
           in 5G systems and beyond: Performance analysis and design insights

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      Authors: Xianling Wang;Haijun Zhang;Yitong Liu;Chen Zhu;Yue Tian;
      Pages: 179 - 194
      Abstract: In next generation networks, mobility management will be a critical issue due to dense base station (BS) deployment, for which user and control plane split architecture provides a promising solution. Jointly designing such architecture with nonorthogonal transmission brings in more flexibility to further improve system efficiency. This paper proposes a non-orthogonal transmission design for user and control plane split architecture. In this design, user equipments (UEs) will select the BS providing the strongest received signal to associate its data channel, but constantly connect its control channel to the nearest macro-cell BS (MBS). Upon non-orthogonal transmission, an MBS can multiplex data traffics and control signals on the same resource. Stochastic geometry based analysis is carried out to investigate outage probability, which extends its regular definition by jointly considering data and control channels, and then mobility-aware outage rate. Numerical results show that: 1) The proposed split architecture alleviates the increase in handover rate for ultra dense networking, compared with conventional architecture. 2) Non-orthogonal transmission outperforms traditional orthogonal transmission in the split architecture, because it is capable of accommodating more control channels. 3) By carefully adjusting power levels, minimum outage probabilities can be reached for macro-cell UEs in the proposed design.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • BER performance analysis of asynchronous NOMA with arbitrary phase offset

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      Authors: Chang Liu;Sheng Wu;Chunxiao Jiang;Hongwen Yang;
      Pages: 195 - 208
      Abstract: An asynchronous transmission scenario for non-orthogonal multiple access (NOMA) user signals with arbitrary phase offset is investigated in this paper. To improve the system performance in the user power-balanced conditions, we adopt a synthetic detection method at the receiver, i.e., the jointly optimal maximal likelihood detection aided triangular successive interference cancellation (JO ML-TSIC) method. Analytical bit error rate (BER) solutions are obtained for a two-user case with the optimal, intentional one-half symbol period time delay implemented between the user signals. Furthermore, closed-form BER solutions for the case using the triangular successive interference cancellation (TSIC) detection method are also derived for comparisons. Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation (SIC) receiver in all the conditions concerned. The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Performance analysis of N-continuous OFDM systems with low-interference
           signal

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      Authors: Peng Wei;Yue Xiao;Shuxia Yan;Wei Xiang;
      Pages: 209 - 230
      Abstract: N-continuous orthogonal frequency division multiplexing (NC-OFDM) is a promising multi-carrier transmission waveform conceived for improving sidelobe suppression performance. To reduce the severe inband interference in traditional NC-OFDM, we have proposed low-interference signal modeling for NC-OFDM. However, spectral leakage and error may be undesirably increased owing to the limited continuous differentiability of the smooth signal. In this paper, the low-interference scheme is investigated in terms of power spectrum density (PSD) and error performance, under the parameters of the highest derivative order (HDO) and the length of the smooth signal, to prove and quantify its advantages over traditional NC-OFDM. In the context of PSD, sidelobe decay is evaluated upon considering two discontinuous points due to the finite continuity of the smooth signal and its higher-order derivatives. Furthermore, it was shown that the low-interference scheme incurs small signal-to-noise ratio (SNR) loss and bit error rate (BER) for a short length of the smooth signal or a small HDO compared to traditional NC-OFDM. Meanwhile, due to the cyclostationarity loss imposed by the smooth signal, an effective solution is suggested for the time synchronization in a practical system. Based on analyses and simulation results, the tradeoffs between sidelobe suppression and BER are studied.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Design and energy estimation of QCA based simple data path selector cum
           router unit for nano communication

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      Authors: Angshuman Khan;Rajeev Arya;
      Pages: 231 - 240
      Abstract: Quantum dot cellular automata (QCA) is promising nanotechnology due to the three main advantages: faster speed, nanoscale size, and ultra-small power consumption. This paper proposed a simple data path selector cum router as the ‘multiplexer-channel-demultiplexer’ unit using QCA, an unavoidable building block of nano communication. A Simple 2×2 block and the extended 4×4 block of data path selectors have been proposed in this article. The layouts of the proposed designs have been verified in QCADesigner, and the energy dissipation has been evaluated using two tools, QCAPro and QCQDesigner-E(QDE). The suggested designs reached a significant improvement in cell complexity (cell count) and covered area over the existing designs. In precise, the proposed 2×2 (4 × 4) block shows 86% (63%) lower cell complexity and 87% (37%) smaller area than the prior reported similar designs. In addition, the currently reported 2 × 2 (4 × 4) unit has 86% (60%) lower QDE based energy dissipation compared with prior reported designs.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Weighting function modification used for phase transform-based time delay
           estimation

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      Authors: Xue Yang;Changchun Bao;Zihao Cui;
      Pages: 241 - 256
      Abstract: Generalized cross-correlation is considered as the most straightforward time delay estimation algorithm. Depending on various weighting function, different methods were derived and a straightforward method, named phase transform (PHAT) has been widely used. PHAT is well-known for its robustness to reverberation and its sensitivity to noise, which is partly due to the fact that PHAT distributes same weights to the frequencies dominated by signal or noise. To alleviate this problem, two weighting functions are proposed in this paper. By taking a posteriori signal-to-noise ratio (SNR) into account to classify reliable and unreliable frequencies, different weights could be assigned. The first proposed weighting function borrows the idea of binary mask and distributes same weights to frequencies in same set, whereas, the second one assigns weights based on coherence function. Experiments showed the robustness of proposed methods to reverberation and noise for improving the performance of time delay estimation through various criteria.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • On cost minimization for cache-enabled D2D networks with recommendation

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      Authors: Yu Hua;Yaru Fu;Qi Zhu;
      Pages: 257 - 267
      Abstract: To accommodate the tremendous increase of mobile data traffic, cache-enabled device-to-device (D2D) communication has been taken as a promising technique to release the heavy burden of cellular networks since popular contents can be pre-fetched at user devices and shared among subscribers. As a result, cellular traffic can be offloaded and an enhanced system performance can be attainable. However, due to the limited cache capacity of mobile devices and the heterogeneous preferences among different users, the requested contents are most likely not be proactively cached, inducing lower cache hit ratio. Recommendation system, on the other hand, is able to reshape users' request schema, mitigating the heterogeneity to some extent, and hence it can boost the gain of edge caching. In this paper, the cost minimization problem for the social-aware cache-enabled D2D networks with recommendation consideration is investigated, taking into account the constraints on the cache capacity budget and the total number of recommended files per user, in which the contents are sharing between the users that trust each other. The minimization problem is an integer non-convex and non-linear programming, which is in general NP-hard. Therewith, we propose a time-efficient joint recommendation and caching decision scheme. Extensive simulation results show that the proposed scheme converges quickly and significantly reduces the average cost when compared with various benchmark strategies.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Over-the-air testing for dual-polarized MIMO devices: Setup design and
           validation

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      Authors: Yong Li;Junli Li;Xiang Zhang;Guiming Wei;
      Pages: 268 - 281
      Abstract: Over-the-air (OTA) testing is considered as the only feasible solution to evaluate radio performances of the fifth-generation (5G) wireless devices which feature two important technologies, i.e., massive multiple-input multiple-output (MIMO) and millimeter-wave (mmWave). The multi-probe anechoic chamber (MPAC) based OTA setup is able to emulate realistic multipath propagation conditions in a controlled manner. This paper investigates an MPAC OTA setup which is capable of evaluating the performances of 5G base stations as the devices-under-test (DUTs) which are equipped with dual-polarized antennas. Both end-to-end setup and probe configuration for the considered MPAC setup will be elaborated. Furthermore, since building a practical MPAC setup is expensive, time-consuming, and error-prone, an end-to-end software testbed is established for validation purpose to avoid technical risks before finalizing an MPAC setup. The architecture of the testbed is presented, which can emulate both the channel profiles perceived by the DUT and the physical-layer behaviors of the considered link conforming to 5G new radio (NR) specifications. Results show that the performances under the emulated channel agree well with those under the target channel, validating the accuracy and effectiveness of the MPAC method.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • An enhanced searching strategy for multi-agent mobile applications

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      Authors: Xiaoyu Zhang;Wei Liu;Fangchun Yang;
      Pages: 282 - 296
      Abstract: Multi-agent mobile applications play an essential role in mobile applications and have attracted more and more researchers' attention. Previous work has always focused on multi-agent applications with perfect information. Researchers are usually based on human-designed rules to provide decision-making searching services. However, existing methods for solving perfect-information mobile applications cannot be directly applied to imperfect-information mobile applications. Here, we take the Contact Bridge, a multi-agent application with imperfect information, for the case study. We propose an enhanced searching strategy to deal with multi-agent applications with imperfect information. We design a self-training bidding system model and apply a Recurrent Neural Network (RNN) to model the bidding process. The bridge system model consists of two parts, a bidding prediction system based on imitation learning to get a contract quickly and a visualization system for hands understanding to realize regular communication between players. Then, to dynamically analyze the impact of other players' unknown hands on our final reward, we design a Monte Carlo sampling algorithm based on the bidding system model (BSM) to deal with imperfect information. At the same time, a double-dummy analysis model is designed to efficiently evaluate the results of sampling. Experimental results indicate that our searching strategy outperforms the top rule-based mobile applications.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
  • Modeling and channel estimation for piezo-acoustic backscatter assisted
           underwater acoustic communications

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      Authors: Junliang Lin;Gongpu Wang;Zijian Zheng;Ruyi Ye;Ruisi He;Bo Ai;
      Pages: 297 - 307
      Abstract: Relying on direct and converse piezoelectric effects, piezo-acoustic backscatter (PAB) technology reflects ambient acoustic signals to enable underwater backscatter communications at near-zero power, which was first realized through a prototype. In this paper, we propose a mathematical model of the PAB assisted underwater acoustic (UWA) communication, and address the sparse channel estimation problem. First, we present a five-stage backscatter process to derive the backscatter coefficient, and propose the channel model for the shallow-water communications. Then, we formulate the shallow-water acoustic channel estimation problem as a sparse vector recovery one according to the compressed sensing theory, and leverage the orthogonal matching pursuit (OMP) algorithm to obtain the channel estimator. Finally, simulation results are provided to corroborate our proposed studies.
      PubDate: Nov. 2022
      Issue No: Vol. 19, No. 11 (2022)
       
 
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