著者

He He Jun-Han Wang Shun Kojima Kazuki Maruta Chang-Jun Ahn

出版者

Research Institute of Signal Processing, Japan

雑誌

Journal of Signal Processing (ISSN:13426230)

巻号頁・発行日

vol.27, no.3, pp.49-57, 2023-05-01 (Released:2023-05-01)

参考文献数

16

被引用文献数

1

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In a high-speed moving mobile environment, the channel state information (CSI) in the last part of the packet is different from the actual channel in the beginning part. Therefore, the channel estimation accuracy is degraded, especially when a small number of pilot symbols are used to ensure transmission efficiency. For the above reasons, it is necessary to compensate for CSIs to achieve reliable communication. Decision feedback channel estimation (DFCE) has been widely considered to be one of the channel tracking methods. However, the presence of time and frequency selective fading environments still causes estimation errors due to the decision-making process. We focused on the time-frequency domain response of the CSIs, which can be represented as a two-dimensional image. This paper newly proposes a regression convolutional neural network (CNN) based channel tracking scheme using the time-frequency domain response of the CSIs by DFCE for training and prediction to solve these problems. Computer simulation results demonstrate that the proposed scheme can achieve higher BER performance than the conventional schemes.

著者

Nobutaka Funaki Kazuki Maruta Chang-Jun Ahn

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.10, no.6, pp.324-330, 2021-06-01 (Released:2021-06-01)

参考文献数

6

被引用文献数

1

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This letter proposes adaptive null-space expansion (NSE) for multiuser massive MIMO according to users’ mobility. NSE can improve the robustness of multi-user spatial multiplexing in a time-varying channel by expanding null-steering to multiple past channels. Its superiority was verified under the unified moving speed among users. In a realistic environment, users with different speeds coexist. Null-space dimension, which is the number of nullified channels per user terminal, should be optimized in accordance with users’ mobility so as to maximize the beamforming gain and nullification capability. In our proposal, we first show that user mobility can be classified by observing the singular value of time-varying channels. Computer simulation then clarifies that output SINR can be improved by assigning null space dimensions respective to user moving speeds.

著者

Katsuya Senoo Kazuki Maruta Takatoshi Sugiyama Chang-Jun Ahn

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.9, no.1, pp.13-18, 2020 (Released:2020-01-01)

参考文献数

6

被引用文献数

2

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In order to achieve high-speed and large-capacity communication, efficient use of frequency resources even over different wireless communication systems is an important issue. We previously proposed the spectrum superposing scheme using subcarrier transmission power assignment (STPA) and blind adaptive array (BAA). Even when multiple systems use the same frequency band, the secondary system enables the both receivers to mitigate inter-system interference by STPA-BAA. However, STPA-BAA has a problem that the operational region of the secondary system is limited due to low-level subcarriers. This paper attempts to resolve this issue by introducing subcarrier modulation adaptation. It can effectively expand the operational region of our proposed approach even in the low signal-to-noise-power-ratio (SNR) situation.