Effects of Channel Aging in Massive MIMO Systems

Truong, Kien T.,Heath, Robert W. Jr. The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.4

Multiple-input multiple-output (MIMO) communication may provide high spectral efficiency through the deployment of a very large number of antenna elements at the base stations. The gains from massive MIMO communication come from the use of multi-user MIMO on the uplink and downlink, but with a large excess of antennas at the base station compared to the number of served users. Initial work on massive MIMO did not fully address several practical issues associated with its deployment. This paper considers the impact of channel aging on the performance of massive MIMO systems. The effects of channel variation are characterized as a function of different system parameters assuming a simple model for the channel time variations at the transmitter. Channel prediction is proposed to overcome channel aging effects. The analytical results on aging show how capacity is lost due to time variation in the channel. Numerical results in a multicell network show that massive MIMO works even with some channel variation and that channel prediction could partially overcome channel aging effects.

Inter-Vehicle Cooperation Channel Estimation for IEEE802.11p V2I Communications

Yan Yang,Fei Dan,Shuping Dang 한국통신학회 2017 Journal of communications and networks Vol.19 No.3

The impact of imperfect channel state information (CSI) is particularly serious in vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communications.~Considering the sparse characteristics of V2I channels, this paper proposes an inter-vehicle cooperation channel estimation (IVC-CE) method at the IEEE 802.11p physical layer, and the effects of outdated CSI can be mitigated by single or multiple vehicle measurements.~With these assisted measurements, we can develop an interpolation-assisted channel estimation technique to obtain accurate CSI.~To select optimum measurements from a group of channel estimates, we utilize the position and velocity of a vehicle as a priori information.~We investigate the validity of the IVC-CE technique with the traditional linear minimum mean-squared error algorithm and present a scalable data transmission scheme at the physical layer.~The performance of IVC-CE is analyzed by its mean squared error and bit error rate in a fast fading channel environment. Simulations and numerical results show the merits of the proposed techniques, which can significantly enhance estimation performance and support safety related data transmissions for vehicular ad hoc networks.

Effects of Channel Aging in Massive MIMO Systems

Kien T. Truong,Robert W. Heath, Jr. 한국통신학회 2013 Journal of communications and networks Vol.15 No.4

Multiple-inputmultiple-output (MIMO) communication may provide high spectral efficiency through the deployment of a very large number of antenna elements at the base stations. The gains from massive MIMO communication come from the use of multi-user MIMO on the uplink and downlink, but with a large excess of antennas at the base station compared to the number of served users. Initial work on massive MIMO did not fully address several practical issues associated with its deployment. This paper considers the impact of channel aging on the performance of massiveMIMO systems. The effects of channel variation are characterized as a function of different system parameters assuming a simple model for the channel time variations at the transmitter. Channel prediction is proposed to overcome channel aging effects. The analytical results on aging show how capacity is lost due to time variation in the channel. Numerical results in a multicell network show that massive MIMO works even with some channel variation and that channel prediction could partially overcome channel aging effects.

Outage Probability of Two-Way Full-Duplex Relaying With Imperfect Channel State Information

Dongwook Choi,Jae Hong Lee IEEE 2014 IEEE Communications Letters Vol.18 No.6

<P>In this letter, we investigate two-way full-duplex (TWFD) relaying with a residual loop interference (LI). In the TWFD relaying, two full-duplex users exchange data with each other via a full-duplex relay, and each node attempts to subtract the estimate of the residual LI from its received signal. We derive the exact integral and approximate closed-form expressions for the outage probability of the TWFD relaying in case of perfect and imperfect channel state information. Monte Carlo simulations verify the validity of analytical results.</P>

Capacity Bound for Discrete Memoryless User-Relaying Channel

( Ki-ryang Moon ),( Do-sik Yoo ),( Seong-jun Oh ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.3

In this paper, we consider the discrete memoryless user relaying channel (DMURC) in which a user-relay switches its operational mode symbol-by-symbol. In particular, we obtain upper and lower bounds on the channel capacity for the general DMURC and then show that these the upper and lower bounds coincide for degraded DMURC. It is also shown that the capacity of the degraded DMURC can be achieved using two separate codebooks corresponding to the two UR states. While the UR is assumed to switch states symbol-by-symbol, the results in this paper is the same as when the UR switches states packet-by-packet.

WiSECam: A CSI-Based Deep Learning Motion Detection for Wireless Cameras

DinhNguyen Dao(다오딩응웬),Muhammad Salman(무하마드 살만),YoungTae Noh(노영태) 한국통신학회 2021 韓國通信學會論文誌 Vol.46 No.12

A Channel State Information Feedback Method for Massive MIMO-OFDM

Riichi Kudo,Simon M. D. Armour,Joe P. McGeehan,Masato Mizoguchi 한국통신학회 2013 Journal of communications and networks Vol.15 No.4

Combining multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) with a massive number of transmit antennas (massive MIMO-OFDM) is an attractive way of increasing the spectrum efficiency or reducing the transmission energy per bit. The effectiveness of Massive MIMOOFDM is strongly affected by the channel state information (CSI)estimation method used. The overheads of training frame transmission and CSI feedback decrease multiple access channel (MAC)efficiency and increase the CSI estimation cost at a user station (STA). This paper proposes a CSI estimation scheme that reduces the training frame length by using a novel pilot design and a novel unitary matrix feedback method. The proposed pilot design and unitary matrix feedback enable the access point (AP) to estimate the CSI of the signal space of all transmit antennas using a small number of training frames. Simulations in an IEEE 802.11n channel verify the attractive transmission performance of the proposed methods.

Towards Deep Learning-aided Wireless Channel Estimation and Channel State Information Feedback for 6G

Kim, Wonjun,Ahn, Yongjun,Kim, Jinhong,Shim, Byonghyo 한국통신학회 2023 Journal of communications and networks Vol.25 No.1

Deep learning (DL), a branch of artificial intel-ligence (AI) techniques, has shown great promise in variousdisciplines such as image classification and segmentation, speechrecognition, language translation, among others. This remarkablesuccess of DL has stimulated increasing interest in applyingthis paradigm to wireless channel estimation in recent years. Since DL principles are inductive in nature and distinct fromthe conventional rule-based algorithms, when one tries to useDL technique to the channel estimation, one might easily getstuck and confused by so many knobs to control and smalldetails to be aware of. The primary purpose of this paper isto discuss key issues and possible solutions in DL-based wirelesschannel estimation and channel state information (CSI) feedbackincluding the DL model selection, training data acquisition, andneural network design for 6G. Specifically, we present several casestudies together with the numerical experiments to demonstratethe effectiveness of the DL-based wireless channel estimationframework.

A Channel State Information Feedback Method for Massive MIMO-OFDM

Kudo, Riichi,Armour, Simon M.D.,McGeehan, Joe P.,Mizoguchi, Masato The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.4

Combining multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) with a massive number of transmit antennas (massive MIMO-OFDM) is an attractive way of increasing the spectrum efficiency or reducing the transmission energy per bit. The effectiveness of Massive MIMO-OFDM is strongly affected by the channel state information (CSI) estimation method used. The overheads of training frame transmission and CSI feedback decrease multiple access channel (MAC) efficiency and increase the CSI estimation cost at a user station (STA). This paper proposes a CSI estimation scheme that reduces the training frame length by using a novel pilot design and a novel unitary matrix feedback method. The proposed pilot design and unitary matrix feedback enable the access point (AP) to estimate the CSI of the signal space of all transmit antennas using a small number of training frames. Simulations in an IEEE 802.11n channel verify the attractive transmission performance of the proposed methods.

A Simple N^th Best-Relay Selection Criterion for Opportunistic Two-Way Relay Networks under Outdated Channel State Information

( Jinglan Ou ),( Haowei Wu ),( Qi Wang ),( Yutao Zou ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.10

The frequency spectrum available for the wireless communication is extremely crowded. In order to improve the spectral efficiency, the two-way relay networks have aroused great attention. A simple N^th best-relay selection criterion for the opportunistic two-way relay networks is proposed, which can be implemented easily by extending the distributed timer technique in practice, since the proposed criterion is mainly based on the channel gains. The outage performance of the proposed relay selection scheme is analyzed under the outdated channel state information (CSI), and a tight closed-form lower bound and asymptotic value of the outage probability over Rayleigh fading channels are obtained. Simulation results demonstrate that the tight closed-form lower bound of the outage probability very closely matches with simulated ones in the whole SNR region, and the asymptotic results provide good tight approximations to the simulation ones, especially in the high SNR region.