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This paper proposes a game-theoretic framework for analyzing the decentralized and centralized control of smart grids based on the availability of information. For the demand response, demand-side actors in smart grids need to obtain various types of information via communication, e.g., a house with a photovoltaic (PV) power system acts efficiently based on the weather forecasts. In contrast, the...
In wireless sensor networks, individual nodes must be batteryless to make them maintenance-free, which is particularly important for networks that have an enormous number of nodes. When these wireless batteryless nodes are microwave-powered devices, they would necessitate scheduling of power and data transmission. In addition, to ensure network sustainability, a constant amount of energy should be...
This paper proposes a novel heterodyne multiband multiple-input multiple-output (MIMO) receiver with baseband automatic gain control (AGC) for cognitive radios. In the receiver, the analog baseband AGC is introduced to avoid the baseband signals exceeding the voltage reference of analog-to-digital converters (ADCs). This paper proposes a novel technique to estimate the analog devices imperfection...
This paper describes a QoS control scheme for a wide area ubiquitous wireless network which is designed to accommodate many wireless terminals (WTs), such as sensors and actuators, in a large cell area. The purpose of this paper is to establish a QoS control scheme in a media access control (MAC) layer that can hold the transmission delay time of high priority (HP) class traffic within a predefined...
As a promising wireless access standard for machine-to-machine (M2M) networks, the IEEE 802.11 task group ah has been discussing a new standard which is based on the wireless local area network (WLAN) standard. This new standard will support an enormous number of stations (STAs) such as 6000 STAs. To mitigate degradation of the throughput and delay performance in WLANs that employ a carrier sense...
This paper reports a feasibility study including experimental implementation of a battery-less wireless sensor whose power is supplied by a microwave power transmitter. In particular, both microwave power transmissions (MPTs) and wireless communications using wireless local area networks (WLANs) are performed on the same frequency band, 2.4 GHz, to achieve high spectral efficiency. In this case, time...
In this paper, microwave power and sensing data transmission scheduling for machine-to-machine (M2M) wireless networks comprising enormous numbers of sensors is discussed. Due to the large numbers involved, the sensors are required to be battery-less so that they can be maintenance-free. When microwave power and sensing data are simultaneously transmitted, they interfere with each other at the receiver...
In a multi-user multiple-input multiple-output (MU-MIMO) system, zero-forcing precoding can completely eliminates inter-user interference when the perfect channel state information is available at the base station. However, in time-varying channels, the transmission performance of MU-MIMO systems is severely degraded due to inter-user interference. In this paper, channel prediction is employed for...
In wireless sensor networks, individual nodes must be batteryless to make themselves maintenance-free, which is particularly important for networks that have an enormous number of nodes. Wireless and batteryless sensors can be powered by energy harvesting or wireless power transmission, and they store energy in capacitors. Microwave power transmission is a wireless power transmission scheme that can...
The Lattice-reduction aided MIMO receiver with virtual channels has been proposed that can increase transmission speed for a user in downlinks. Although the proposed receiver achieves superior performance even when the number of receive antennas is much less than that of spatially multiplexed streams, however, the receiver has more computational complexity than conventional lattice reduction-aided...
Transmit power control to minimize transmit power for multi-user distributed antenna systems (MU-DASs) is necessary to improve spectrum efficiency. In previous work, distributed transmit power control (DTPC) algorithm for cellular MIMO systems has been developed based on uplink-downlink duality. The performance of this DTPC algorithm in MU-DASs is evaluated in this paper because MU-DASs is different...
As the demand for high-throughput communications in wireless LANs increases, the need for expanding channel bandwidth also increases. However, the use of wider band channels results in the decrease of the number of channels available. Therefore, if multiple access points (APs) are in proximity and the cells overlap, it is difficult for each AP to use an orthogonal channel, and competitions thus increase...
In this paper, the end-to-end packet error rate (PER) performance of a space-time block code (STBC) based multi-hop cooperative relaying system is discussed. This system consists of a source, a destination, and two STBC based cooperative relays in each hop. These relays decode their received packets and forward the packets only when no error is found. In this system, there are conditions where the...
In this paper, implementation of a multi-user MIMO experimental system is presented. Linear spatial precoding and a simple two- way channel estimation technique are adopted in the experimental system. In-lab and field transmission experiments are carried out and the performance is evaluated. The impact of channel estimation error under average channel gain discrepancy between two mobile stations is...
A practical and efficient vector quantization called partitioned vector quantization (P-VQ) based non-linear precoder for MIMO downlink broadcasting channels has been analyzed in this paper. P- VQ has been found to be an efficient way of reducing the memory requirements and search complexity in conventional VQ systems, especially for large MIMO. Simulation results reveal that P-VQ technique can enhance...
The spread of the Internet has given rise to strong demands for real-time services such as voice and streaming video. Since these services require guarantees that may include transmission rate, delay, and delay variance, the network, including the wireless access networks, must offer quality of service (QoS) guarantees. However, no radio access system fully supports QoS controls. In this paper, we...
In this paper, a method for a multi-operator mobile relay node (RN) for cellular networks on a bus or train is proposed. The introduction of RNs enables an improvement in the spectral efficiency because an antenna with higher gain than that of user equipment (UE) can be installed in an RN. However, installing different RNs for different operators is not efficient because of the large amount of space...
This paper proposes a novel radio frequency (RF) devices imperfection estimation scheme for the heterodyne multiband multiple-input multiple-output (MIMO) receiver with the baseband automatic gain control (AGC) for cognitive radios. It is quantitatively shown that the proposed estimation scheme allows analog-to-digital converters (ADCs) with lower resolution to be applied to the receiver than the...
Cognitive radios are of interest because they are capable of high frequency utilization efficiency. Multiband multiple-input multiple-output (MIMO) receivers based on heterodyne reception have been proposed for use in cognitive radios. This paper proposes a reduced-complexity multiband MIMO receiver that can achieve high performance by correcting the imperfection of the Hilbert transformer in the...
In this paper, we propose a receiver using the concept of a "virtual channel" and Turbo codes for multiuser multiple-input multiple-output (MU-MIMO) systems with cooperating transmitters. In order to reduce feedback information from receivers, a precoding method with reduced channel state information (CSI) is needed. Although signals interfere with each other in such a system, the proposed...
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