Details of a Researcher - Sanada, Yukitoshi

Papers - Sanada, Yukitoshi

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Frequency Resource Allocation Using Combined Evaluation Function in High Throughput Satellite Communication System

OTSURU Go, SANADA Yukitoshi, TSUJI Hiroyuki, MIURA Amane

IEICE Transactions on Communications (The Institute of Electronics, Information and Communication Engineers) E108.B ( 4 ) 531 - 539 2025.04

Joint Work, Accepted, ISSN 09168516

The resource allocation in high throughput satellites (HTSs) has been extensively investigated due to their payload ability to provide high-capacity and high-speed communication. To date, research has been conducted on variable beam arrangement using digital beamforming technology and on illumination patterns using beam hopping. In addition, there has been a great deal of research on flexible frequency resource allocation realized by digital channelizers. However, limited attention has been paid to a coordination of system throughput and fairness among user equipments (UEs) in these previous studies. In our previous paper, we proposed a frequency resource allocation model based on a beam-indexes-series finite Markov decision process. The policies of the resource allocation determined by a network operation center were only focused on maximizing either the number of allocated UEs or the system throughput. In this paper, we introduce a combined evaluation function that considers both the system throughput and the number of allocated UEs. This allows for the simultaneous optimization of communication capacity and fairness of communication opportunities. The superiority of the proposed resource allocation scheme and combined evaluation function is demonstrated through computational simulation in the comparison of the allocation scheme in the prior research. The operator is then able to coordinate the trade-off between system throughput and fairness among UEs.

Affiliation Macrocell Switching of Picocells in Uplink for Distributed Antenna System

Takada A., Sanada Y.

Proceedings of 2024 IEEE 29th Asia Pacific Conference on Communications: Sustainable Connectivity: Advancing Green Technologies for a Smarter Future, APCC 2024 549 - 554 2024.11

Joint Work, Last author, Accepted

This paper proposes the affiliation macrocell switching of picocells in a distributed antenna system (DAS). In a conventional DAS, a macrocell is composed of a fixed number of picocells. On the other hand, in the proposed scheme, picocells can switch their affiliation to adjacent macrocells so that the throughputs of cell-edge users improve. The proposed scheme aims to improve a system throughput with the moderate increase of backhaul complexity. Numerical results obtained through computer simulation show that the proposed scheme improves the system throughput by approximately 0.3 bps/Hz/cell and maintains user fairness. Moreover, the system throughput improves regardless of the distance between distributed antennas.

Access to Document (DOI)

MMSE Equalization-Based MIMO Demodulation with Random Walk along Gradient Descent Direction

Kikuchiahra R., Sanada Y.

Proceedings of 2024 IEEE 29th Asia Pacific Conference on Communications: Sustainable Connectivity: Advancing Green Technologies for a Smarter Future, APCC 2024 456 - 461 2024.11

Last author, Accepted

This paper proposes a minimum mean square error (MMSE) equalization-based multi-input multi-output (MIMO) demodulation scheme with Metropolis-Hastings random walk along a gradient descent direction. The conventional scheme using intermediate search points works effectively for higherorder modulation symbols. However, its performance is deteriorated for lower-order modulation symbols. The proposed scheme suppresses the coefficients in the offdiagonal components of a channel matrix by applying MMSE equalization and improves performance in low signal-to-noise power ratio conditions even for lowerorder modulation symbols. Numerical results obtained thorough computer simulation show that the proposed scheme improves by about 2.0 dB at a bit error rate of 10-2 when the number of iteraitons is 10 for QPSK symbols with 64 transmit and receive antennas.

Access to Document (DOI)

Throughput Performance of Uplink Beamforming Transmission through Terminal Collaboration

Nakaoka R., Ando E., Sanada Y.

IEEE Vehicular Technology Conference 2024.10

Joint Work, Last author, Accepted, ISSN 15502252

This paper evaluates the throughput performance of uplink beamforming transmission through terminal collaboration. In the proposed scheme multiple user equipments (UEs) form a group and transmit signals synchronously to enhance the power of a received signal at a base station. The signal transmitted through terminal collaboration is selected according to proportional fairness scheduling. Thus, fairness among UEs is maintained simultaneously with system throughput improvement. Numerical results obtained through computer simulation show that the system throughput grows as the number of UEs in the group increases. It is also shown that the proposed scheme increases the system throughput by about 0.5-1.5 bps/Hz.

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Performance of User Grouping Schemes in Collaborative MIMO Reception with a Focus on User Fairness

Ando E., Sanada Y.

IEEE Vehicular Technology Conference 2024.10

Joint Work, Last author, Accepted, ISSN 15502252

This paper proposes user equipment (UE) grouping schemes that take user fairness into account in collaborative multiple-input multiple-output reception. In previous research, the criterion for UE grouping to improve system throughput is proposed. However, the user fairness is deteriorated if these schemes focus on the system throughput. In this paper, the range of the received signal power is restricted to reduce the difference among user throughput. Numerical results obtained through computer simulation show that there is a trade-off relationship between the user throughput and the user fairness via the range of the received signal power.

Access to Document (DOI)

Multi-User Signal Detection with UAV Relay Station in Uplink Heterogeneous Network

Furuichi M., Sanada Y.

IEEE Vehicular Technology Conference 2024.10

Joint Work, Last author, Accepted, ISSN 15502252

In this paper multi-user signal reception with an unmanned ariel vehicle (UAV) relay station (RS) in an uplink heterogeneous network is proposed. In a conventional heterogeneous network cooperative signal reception between a UAV RS and a macro base station (BS) has rarely investigated. Therefore, in this paper, minimum mean square error (MMSE) multi-user signal detection with the UAV RS and the macro BS is applied to improve a system throughput. In the proposed scheme, the UAV RS works as an amplify-and-forward relay station. The link between the UAV RS and the macro BS is assumed to be connected through a millimeter wave link. Numerical results obtained enough computer simulation show that the throughputs of both users supported by the UAV RS and the macro BS improve and a fairness index between users increases.

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Performance of Collaborative MIMO Reception with User Grouping Schemes

E. Ando and Y. Sanada,

IEICE Trans. on Commun. (The Institute of Electronics, Information and Communication Engineers) E107-B ( 1 ) 253 - 261 2024.01

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 09168516

This paper proposes user equipment (UE) grouping schemes and evaluates the performance of a scheduling scheme for each formed group in collaborative multiple-input multiple-output (MIMO) reception. In previous research, the criterion for UE grouping and the effects of group scheduling has never been presented. In the UE grouping scheme, two criteria, the base station (BS)-oriented one and the UE-oriented one, are presented. The BS-oriented full search scheme achieves ideal performance though it requires knowledge of the relative positions of all UEs. Therefore, the UE-oriented local search scheme is also proposed. As the scheduling scheme, proportional fairness scheduling is used in resource allocation for each formed group. When the number of total UEs increases, the difference in the number of UEs among groups enlarges. Numerical results obtained through computer simulation show that the throughput per user increases and the fairness among users decreases when the number of UEs in a cell increases in the proposed schemes compared to those of the conventional scheme.

Belief Propagation Detection with MRC Reception and MMSE Pre-cancellation for Overloaded MIMO

Y. Suzuki and Y. Sanada,

IEICE Trans. on Commun. (The Institute of Electronics, Information and Communication Engineers) E107-B ( 1 ) 154 - 162 2024.01

Research paper (scientific journal), Joint Work, Last author, Accepted, ISSN 09168516

In this paper, belief propagation (BP) multi-input multi-output (MIMO) detection with maximum ratio combining (MRC) and minimum mean square error (MMSE) pre-cancellation is proposed for overload MIMO. The proposed scheme applies MRC before MMSE pre-cancellation. The BP MIMO detection with MMSE pre-cancellation leads to a reduction in diversity gain due to the decreased number of connections between variable nodes and observation nodes in a factor graph. MRC increases the diversity gain and contributes to improve bit error rate (BER) performance. Numerical results obtained through computer simulation show that the BERs of the proposed BP MIMO detection with MRC and MMSE pre-cancellation yields bit error rates (BERs) that are approximately 0.5dB better than those of conventional BP MIMO detection with MMSE pre-cancellation at a BER of 10-3.

Gradient Descent Direction Random Walk MIMO Detection using Intermediate Search Point

N. Ito and Y. Sanada

IEICE Trans. on Commun. E106-B ( 11 ) 1192 - 1199 2023.11

Last author, Accepted

Gain and Output Optimization Scheme for Block Low-Resolution DACs in Massive MIMO Downlink

T. Yamakado and Y. Sanada

IEICE Trans. on Commun. (The Institute of Electronics, Information and Communication Engineers) E106-B ( 11 ) 1200 - 1209 2023.11

Research paper (scientific journal), Last author, Accepted, ISSN 09168516

In this paper, a nonlinear quantized precoding scheme for low-resolution digital-analog converters (DACs) in a massive multiple-input multiple-output (MIMO) system is proposed. The nonlinear quantized precoding determines transmit antenna outputs with a transmit symbol and channel state information. In a full-digital massive MIMO system, low-resolution DACs are used to suppress power consumption. Conventional precoding algorithms for low-resolution DACs do not optimize transmit antenna gains individually. Thus, in this paper, a precoding scheme that optimizes individual transmit antenna gains as well as the DAC outputs is proposed. In the proposed scheme, the subarray of massive MIMO antennas is treated virtually as a single antenna element. Numerical results obtained through computer simulation show that the proposed precoding scheme achieves bit error rate performance close to that of the conventional precoding scheme with much smaller antenna gains on a CDL-A channel.

Adaptive Mixing Probability Scheme in Mixed Gibbs Sampling MIMO Signal Detection

K. Chuman and Y. Sanada

IEICE Trans. on Commun. (The Institute of Electronics, Information and Communication Engineers) E106-B ( 12 ) 1463 - 1469 2023.11

Last author, Accepted, ISSN 09168516

This paper proposes an adaptive mixing probability scheme for mixed Gibbs sampling (MGS) or MGS with maximum ratio combining (MRC) in multiple-input multiple-output (MIMO) demodulation. In the conventional MGS algorithm, the mixing probability is fixed. Thus, if a search point is captured by a local minimum, it takes a larger number of samples to escape. In the proposed scheme, the mixing probability is increased when a candidate transmit symbol vector is captured by a local minimum. Using the adaptive mixing probability, the numbers of candidate transmit symbol vectors searched by demodulation algorithms increase. The proposed scheme in MGS as well as MGS with MRC reduces an error floor level as compared with the conventional scheme. Numerical results obtained through computer simulation show that the bit error rates of the MGS as well as the MGS with MRC reduces by about 1/100 when the number of iterations is 100 in a 64×64 MIMO system.

Frequency Resource Allocation Using Q-learning for User Link in High Throughput Satellite Communication

G. Otsuru, Y. Sanada, H. Tsuji, and A. Miura

The 26th International Symposium on Wireless Personal Multimedia Communications 2023.11

Research paper (international conference proceedings), Accepted

Belief Propagation Overloaded MIMO Detection using MRC Reception and MMSE Pre-cancellation

Y. Suzuki and Y. Sanada

IEEE 98th Vehicular Technology Conference 2023.10

Research paper (international conference proceedings), Last author, Accepted, ISSN 15502252

In this paper, belief propagation (BP) multi-input multi-output (MIMO) detection with maximum ratio combining (MRC) and minimum mean square error (MMSE) pre-cancellation is proposed for overload MIMO. In the proposed scheme, MRC is applied before MMSE pre-cancellation. The BP MIMO detection with MMSE pre-cancellation leads to a reduction in diversity gain due to the decreased number of connections between variable nodes and observation nodes in a factor graph. MRC increases the diversity gain and contributes to the improvement of bit error rate (BER) performance. Numerical results obtained through computer simulation show that the BERs of the proposed BP MIMO detection with MRC and MMSE pre-cancellation are about 0.5 dB better than those of the conventional BP with MMSE pre-cancellation at a BER of 10-3.

Access to Document (DOI)

Index Modulation Scheme Using Sparse Perfect Gaussian Integer Sequences on Multicarrier System

K. Yamazaki and Y. Sanada

IEEE 98th Vehicular Technology Conference 2023.10

Research paper (international conference proceedings), Accepted, ISSN 15502252

This paper proposes a new index modulation (IM) scheme for a multi-carrier system, in which spreading codes are selected by index bits. In the proposed scheme OFDM transmission is carried out without spreading codes on some of the subcarriers. At the same time, IM with spreading codes is applied. One of the spreading codes corresponding to index bits is selected in each subcarrier, and the selected code is modulated with assigned coding bits. By increasing the number of coding bits transmitted at a time, the coding rate of the system is reduced, and the overall performance is improved. The OFDM signal and the spreading signal by IM co-exists and interfere with each other. At a receiver, soft replica symbols are generated from the soft output of a demodulator or a decoder and subtracted from the received signal to cancel the interference. Numerical results obtained through computer simulation results show the performance improvement of about 3.0 dB at a bit error rate of 10-4 compared with the conventional multicarrier transmission and 6-path Rayleigh fading channels.

Access to Document (DOI)

User Scheduling at Base Station Cluster Boundary for Massive MIMO Downlink Transmission

YATA Masahito, SANADA Yukitoshi

IEICE Transactions on Communications (The Institute of Electronics, Information and Communication Engineers) E106-B ( 7 ) 586 - 594 2023.09

Research paper (scientific journal), Last author, Accepted, ISSN 09168516

One of the key technologies for the fifth-generation (5G) mobile communication system is massive multiple-input multiple-output (MIMO) that applies beamforming in order to effectively compensate for large propagation losses in high frequency bands and enable the spatial multiplexing of a large number of signal streams over multiple users. To further improve a system throughput, a coordinated cluster system in which a large number of massive MIMO base stations are deployed in high density has been investigated. The dense deployment greatly improves the system capacity by controlling base stations from a centralized base band unit. However, when clusters are closely located in order to serve densely populated areas, inter-beam interference between adjacent clusters becomes more severe. To suppress the interference to adjacent clusters, only a simple beam switch control scheme at a cluster boundary has been investigated as a conventional scheme. In this paper, the scheduling algorithm for massive MIMO downlink transmission near cluster boundaries, which combines two scheduling algorithms, has been proposed. In the proposed scheme, each base station divides its own cell to multiple areas, switches supporting areas sequentially, and serves users in those areas. The numerical results show that the throughputs improve with a little reduction in a fairness index (FI) when the number of users per resource block is one. The FI reaches the highest when the number of users per cell is equal to the number of divided areas. The proposed scheme reduces computational complexity as compared with those of conventional two schemes.

Double CRC-Aided Erasure Demodulation on M-ary Chirp Spread Spectrum Signal

E. Ando and Y. Sanada

URSI General Assembly and Scientific Symposium 2023 2023.08

Research paper (international conference proceedings), Last author, Accepted

UE Set Selection for RR Scheduling in Distributed Antenna Transmission with Reinforcement Learning

OTSURU Go, SANADA Yukitoshi

IEICE Transactions on Communications (The Institute of Electronics, Information and Communication Engineers) E106-B ( 7 ) 586 - 594 2023.07

Research paper (scientific journal), Accepted, ISSN 09168516

In this paper, user set selection in the allocation sequences of round-robin (RR) scheduling for distributed antenna transmission with block diagonalization (BD) pre-coding is proposed. In prior research, the initial phase selection of user equipment allocation sequences in RR scheduling has been investigated. The performance of the proposed RR scheduling is inferior to that of proportional fair (PF) scheduling under severe intra-cell interference. In this paper, the multi-input multi-output technology with BD pre-coding is applied. Furthermore, the user equipment (UE) sets in the allocation sequences are eliminated with reinforcement learning. After the modification of a RR allocation sequence, no estimated throughput calculation for UE set selection is required. Numerical results obtained through computer simulation show that the maximum selection, one of the criteria for initial phase selection, outperforms the weighted PF scheduling in a restricted realm in terms of the computational complexity, fairness, and throughput.

Precoding and Gain Adjustment Scheme for Block LowResolution DACs in Massive MIMO Downlink

T. Yamakado and Y. Sanada

IEEE 97th Vehicular Technology Conference 2023-June 2023.06

Research paper (international conference proceedings), Joint Work, Last author, Accepted, ISSN 15502252

In this paper, a nonlinear quantized precoding and gain adjustment scheme for low-resolution digital-analog converters (DACs) in a massive multiple-input multiple-output (MIMO) system is proposed. The nonlinear quantized precoding determines transmit antenna outputs with a transmit symbol and channel state information. In a full-digital massive MIMO system, low-resolution DACs are used to suppress power consumption. Conventional precoding algorithms for low-resolution DACs do not optimize transmit antenna gains individually. Thus, in this paper, a gain adjustment scheme that optimizes individual transmit antenna gains and the DAC outputs of a virtual block antenna formed by multiple antennas is proposed. Numerical results obtained through computer simulation show that the proposed precoding scheme achieves bit error rate performance close to that of the conventional Gibbs sampling based algorithm with much smaller antenna gains on a i.i.d Rayleigh fading channel.

Access to Document (DOI)

Attribution Macro Cell Switching for CoMP in Distributed Antenna Transmission

T. Tsukamoto, G. Otsuru, and Y. Sanada

IEEE 97th Vehicular Technology Conference 2023-June 2023.06

Research paper (international conference proceedings), Last author, Accepted, ISSN 15502252

In this paper, coordinated multi-point transmission (CoMP) with attribution macro cell switching in distributed antenna transmission is proposed. The proposed scheme is applied to a macro cell system in which each macro cell consists of multiple micro cells. In the proposed scheme, macro cells can be expanded and overlapped with each other, and each micro cell may switch its attribution macro cell. Inter-cell interference is mitigated in conjunction with CoMP transmission. Numerical results obtained through computer simulation show that the largest improvement in a system throughput is realized with three user equipments per macro cell when an inter-antenna distance is 50 meters. The switching frequency corresponds to the amount of the improvement in the throughput. The switching happens less frequently with a longer inter-antenna distance. Thus, the proposed scheme improves the system throughput than the conventional scheme in a dense distributed antenna system.

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【続編】Raspberry PiとSCRATCHでロボットを動かそう（3） Scratch プログラミング編

Sanada Yukitoshi

IEICE Communications Society Magazine (The Institute of Electronics, Information and Communication Engineers) 17 ( 1 ) 6 - 10 2023

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