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We study random access for machine-type commu- nications (MTC) based on the notion of compressive sensing (CS) over a distributed input distributed output (DIDO) system consisting of a number of remote radio heads (RRHs) that are closely located to devices. In a DIDO system, each active device can have a signature that depends on its connectivity to RRHs and the signatures of active devices are estimated...
Short-range wireless positioning and inertial measurement unit (IMU) have been widely used in indoor positioning systems. However, wireless signals fluctuate seriously and the accuracy of low-cost IMU system suffers from gyroscope drift, magnetic interference and accumulative error. In this paper, we propose a fusion positioning system based on Wireless signal, Map information and Inertial sensors,...
We consider wireless communication between Alice and Bob when the intermediate space between Alice and Bob is controlled by Eve. That is, our model divides the channel noise into two parts, the noise generated during the transmission and the noise generated in the detector. Eve is allowed to control the former, but is not allowed to do the latter. While the latter is assumed to be a Gaussian random...
Measuring point traffic volume and point-to-point traffic volume in a road system has important applications in transportation engineering. The connected vehicle technologies integrate wireless communications and computers into transportation systems, allowing wireless data exchanges between vehicles and road-side equipment, and enabling large-scale, sophisticated traffic measurement. This paper investigates...
Many exist localization algorithms are unbiased estimators. However, the estimation performance presents biased feature in the real location systems. On the other hand, many biased location estimators show advantages that unbiased estimators can not achieve, e.g., robust to the noise, more accurate estimation and low complexity. In this paper, we propose a biased localization estimator and a hybrid...
This paper investigates a signal area (SA) estimation method for spectrum measurements. The spectrum measurements is for estimating statistical information of spectrum usage and required latency is not very critical compared to spectrum sensing. SA denotes the area (in time/frequency domain) occupied by the primary user's signal. The traditional approach, which utilizes Fourier transform (FT) and...
“Log-normal shadowing model” is used here for predicting large-scale coverage for wireless sensor networks. Applying this model helps one to estimate the energy capacity of WSN (wireless sensor network), before such systems to be deployed.
System-level timing inconsistency and wireless communication delays are the main uncertainties of existing synchronization mechanisms for wireless sensor networks. Existing solutions mainly rely on timestamp exchanges to estimate clock offset and skew, which results in frequent synchronization, high overhead, and high energy consumption to maintain a well-synchronized network. This paper introduces...
We introduce in this paper two main approaches, Triangulateration (TL) and Angle-Difference-of-Arrival (ADoA) for indoor localization and mapping using single-anchor and millimeter wave (MMW) propagation characteristics. Then, we perform context inference through obstacle localization. To do so, we first include and estimate the positions of virtual anchor nodes (VANs), known as mirrors of the real...
In the mobile industrial human machine interaction (HMI) based on wireless sensor networks, the engineer has to manually select the target machine from a long list which may lead to wrong connection and waste of time. We observe that the engineer should face to the machine during the interaction to ensure that the machine works accurately, and this characteristic makes the proximity estimation algorithm...
Emerging cellular networks integrate the user terminal geo-localization function besides the communication function. The conventional positioning approach is to estimate the terminal location in two-steps: first the distance to all connected base stations is assessed based on signal time-of-flight measurements, then the location is deduced from the distances by multi-lateration. The two-step approach...
Judiciously setting the base station transmit power that matches its deployment environment is a key problem in ultra dense networks and heterogeneous in-building cellular deployments. A unique characteristic of this problem is the tradeoff between sufficient indoor coverage and limited outdoor leakage, which has to be met without explicit knowledge of the environment. In this paper, we address the...
In LTE-Advanced (LTE-A) demodulation reference symbols are employed for pilot aided channel estimation to perform coherent detection. Since these reference symbols are allocated on the same time-frequency positions for all users in Multi-User MIMO (MU-MIMO) operation or for all spatial layers in Single-User MIMO (SU-MIMO), they are designed to be code-domain orthogonal in order to be separable at...
This paper presents a modified MMSE channel estimation for turbo equalization in uplink massive multiple-input multiple-output (MIMO) systems with pilot contamination. Unlike other work on channel estimation in massive MIMO systems where perfect knowledge of inter-cell large scale channel coefficients is assumed, a modified method for data-aided MMSE estimation is proposed without requiring the knowledge...
Due to radio-frequency (RF) circuit mismatch, the channel reciprocity of time-division duplex massive multiple-input multiple-output system is impaired. Under this condition, there exist several different approaches for base station (BS) to obtain the downlink (DL) channel estimate based on the minimum mean-square-error (MMSE) estimation method. We show that with the RF mismatch parameters BS will...
We are developing a Pedestrian-Vehicular Collision Avoidance Support System (P-VCASS) in order to protect pedestrians from traffic accidents with vehicles. P-VCASS is a system that makes observations of pedestrian's moving situations. Drivers of neighboring vehicles are given warnings in advance if there is a possibility of collision between vehicles and pedestrians. Pedestrians moving around in an...
With the rapid deployment of the high speed railway (HSR), the wireless communication in HSR has been one of the indispensable scenarios in the fifth generation (5G) communications. In order to improve the performance of the orthogonal frequency division multiplexing (OFDM) system in the HSR scenarios, we propose an enhanced linear minimum mean square error channel estimation scheme based on multi-path...
For the practical realization of Microwave power transfer (MPT), high-efficiency rectifiers are required. In this paper, we studied on the rectifiers with intermittent input signal. Intermittent signal has high peak-to-average power ratio. Therefore, there exists the possibility of boosting the RF-DC conversion efficiency. However, the operation of a rectifier with intermittent input is not studied...
Phase offset is inevitable in asynchronous physical-layer network coding (PNC) systems, which restricts the accuracy of PNC decoding. To address this issue, this paper proposes a half-blind equalization based on pre-distortion. In the scheme, the intentional phase distortion is pre-brought into the symbols of one user, and then, it is utilized by the relay to equalize the received signals and modify...
This paper proposes a novel algorithm for estimating underdetermined mixing matrix in Wireless Statistic Division Multiplexing (WSDM) system based on the first-order statistics. Firstly, we extend Xu's algorithm to the underdetermined case to estimate the mixing matrix. However, the extended Xu's algorithm employs the conditional expectations which only consider the condition of single source. In...
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