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Ambient backscatter is a new technology that utilizes environmental wireless signals to enable battery-free devices to communicate with each other. In this paper, we investigate the problem of signal detection for the full duplex wireless system utilizing ambient backscatter. Since one of the key technologies of full duplex wireless system is self-interference cancellation, we first estimate the channel...
In this work, we acknowledge the existence of the accumulation of the loopback self-interference when AF protocol is made used of in FDTW relaying and the channel estimation of the loopback channel is not done perfectly as will seen in the section to follow. The accumulation of the loopback self-interference comes from the functionality of FD antenna, which will bring back the transmitted signal to...
We develop a channel estimation algorithm for wideband millimeter wave (mmWave) systems using low-resolution phase shifters (PSs). Since the limited scattering feature of mmWave channels, the estimation problem is formulated as a compressive sensing (CS) problem. To avoid the mismatch between the continuous and discrete spatial frequencies, we propose an adaptive grid matching pursuit algorithm to...
We propose a novel channel estimation technique for intensity modulation/direct detection (IM/DD) based orthogonal frequency division multiplexing visible light communication (OFDM-VLC) systems, utilizing sparse Bayesian dual-variate relevance vector machine (RVM) regression. By exploiting sparse Bayesian framework, dual-variate RVM regression can provide accurate estimation of the real and imaginary...
Millimeter wave (mmWave) communication is favored for its abundant bandwidth. However, the sampling rate scales up with the large bandwidth, thus making it difficult to implement high-resolution analog-to-digital converters (ADCs). In addition, a large-scale array is employed to overcome the high path loss of the mmWave channels. Due to the large number of antennas and the directional feature of the...
In this paper, we investigate the resource allocation problem for the downlink non-orthogonal multiple access (NOMA) system with imperfect channel state information (CSI). We first derive closed-form expressions for the outage probabilities with and without the estimated instantaneous channel fading coefficient for each user. Upper bounds on both of the probability expressions above are proposed....
In this paper, we propose two compressed sensing methods, signed CASS and iterative signed CASS. The effect of signs of entries in a sparse signal could lead to lower accuracy rate of CASS in low SNR region. Thus, signed CASS is proposed to take the signed of a sparse signal into account. The performance of signed CASS is better than CASS in low SNR region and comparable in high SNR region in terms...
Abstract-In VANETs, information exchange plays an important role to make vehicles aware to each other and provide references for safety or non-safety related applications. At intersections, vehicles are forced to maintain a lower mobility thereby have more time to exchange on-road or off-road context information. However, if an effective control scheme is not applied to this specific scenario, a packet...
In this paper, we propose a novel concept of virtual resource chain for Software Defined Campus WLANs (SD-WLANs). A typical SD-WLAN is composed of three layers, i.e., infrastructure, access control and application layers. Firstly, the network control plane is decoupled from the forwarding plane, and soft-defined access points (SD-APs) merely execute the forwarding rules according to the instructions...
A blind and adaptive decision-feedback channel estimation method is proposed for optical intensity-modulated direct detection discrete multitone transmissions. Due to the channel state variation nature of the fiber, periodic channel estimation update is required. In previous works, periodic preambles are transmitted to acquire and track the channel state information at the receiver. In the proposed...
Adaptive channel estimation methods are proposed for reduced guard-interval (RGI) CO-OFDM. Channel estimation is updated adaptively after decoding a sequence of OFDM symbols using LS or MMSE decision-feedback from demodulator to channel estimator.
We propose an algorithm for CO-OFDM receivers to perform overlapped frequency-domain CD and PMD equalization before OFDM symbol demodulation. This approach enables OFDM transmission with a small cyclic prefix overhead of only 0.08%, and can enlarge the frequency averaging length for channel estimation in the presence of high PMD.
Channel estimation for a reduced-guard-interval (RGI) CO-OFDM system shows a unique dependence on the training symbol design in the presence of intra-channel nonlinearities. Because smaller FFT sizes can be used, the RGI CO-OFDM system also demonstrates better nonlinearity tolerance than conventional CO-OFDM with larger FFT sizes.
This paper proposes a low power convolver in channel estimation. It works in the time domain. Ram is used instead of register chains in typical architectures. The power is compared when using different depth of rams. The synthesis results show that the power of the ram based convolver of depth 64 can be reduced to only 57% of that of the register based convolver. And the area can be reduced to 67%.
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