Mobile edge computing (MEC) technology guarantees the privacy and security of large-scale data in the Narrowband-IoT (NB-IoT) by deploying MEC servers near base stations to provide sufficient computing, storage, and data processing capacity to meet the delay and energy consumption requirements of NB-IoT terminal equipment. For the NB-IoT MEC system, this paper proposes a resource allocation algorithm based on deep reinforcement learning to optimize the total cost of task offloading and execution. Since the formulated problem is a mixed-integer non-linear programming (MINLP), we cast our problem as a multi-agent distributed deep reinforcement learning (DRL) problem and address it using dueling Q-learning network algorithm. Simulation results show that compared with the deep Q-learning network and the all-local cost and all-offload cost algorithms, the proposed algorithm can effectively guarantee the success rates of task offloading and execution. In addition, when the execution task volume is 200KBit, the total system cost of the proposed algorithm can be reduced by at least 1.3%, and when the execution task volume is 600KBit, the total cost of system execution tasks can be reduced by 16.7% at most.

It is now becoming important for mobile cellular networks to accommodate all kinds of Internet of Things (IoT) communications. However, the contention-based random access and radio resource allocation used in traditional cellular networks, which are optimized mainly for human communications, cannot efficiently handle large-scale IoT communications. For this reason, standardization activities have emerged to serve IoT devices such as Cellular-IoT (C-IoT). However, few studies have been directed at evaluating the performance of C-IoT communications with periodic data transmissions, despite this being a common characteristic of many IoT communications. In this paper, we give the performance analysis results of mobile cellular networks supporting periodic C-IoT communications, focusing on the performance differences between LTE and Narrowband-IoT (NB-IoT) networks. To achieve this, we first construct an analysis model for end-to-end performance of both the control plane and data plane, including random access procedures, radio resource allocation, establishing bearers in the Evolved Packet Core network, and user-data transmissions. In addition, we include the impact of the immediate release of the radio resources proposed in 3GPP. Numerical evaluations show that NB-IoT can support more IoT devices than LTE, up to 8.7 times more, but imposes a significant delay in data transmissions. We also confirm that the immediate release of radio resources increases the network capacity by up to 17.7 times.

A narrowband active noise control (NANC) system is very effective for controlling low-frequency periodic noise. A frequency mismatch (FM) with the reference signal will degrade the performance or even cause the system to diverge. To deal with an FM and obtain an accurate reference signal, NANC systems often employ a frequency estimator. Combining an autoregressive predictive filter with a variable step size (VSS) all-pass-based lattice adaptive notch filter (ANF), a new frequency estimation method is proposed that does not require prior information of the primary signal, and the convergence characteristics are much improved. Simulation results show that the designed frequency estimator has a higher accuracy than the conventional algorithm. Finally, hardware experiments are carried out to verify the noise reduction effect.

In this paper, we propose a channel-unaware algorithm to suppress the narrowband interference (NBI) for the time synchronization, where multiple antennas are equipped at the receiver. Based on the fact that the characteristics of synchronization signal are different from those of NBI in both the time and spatial domain, the proposed algorithm suppresses the NBI by utilizing the multiple receive antennas in the eigen domain of NBI, where the eigen domain is obtained from the time domain statistical information of NBI. Because time synchronization involves incoherent detection, the proposed algorithm does not use the desired channel information, which is different from the eigen domain interference rejection combining (E-IRC). Simulation results show, compared with the traditional frequency domain NBI suppression technique, the proposed algorithm has about a 2 dB gain under the same probability of detection.

In this paper, a novel approach of a human motion classification system in wireless body area network (WBAN) using received radio signal strength was developed. This method enables us to classify human motions in WBAN using only the radio signal strength during communication without additional tools such as an accelerometer. The proposed human motion classification system has a potential to be used for improving communication quality in WBAN as well as recording daily-life activities for self-awareness tool. To construct the classification system, a numerical simulation was used to generate WBAN propagation channel in various motions at frequency band of 403.5MHz and 2.45GHz. In the classification system, a feature vector representing a characteristic of human motions was computed from time-series received signal levels. The proposed human motion classification using the radio signal strength based on WBAN simulation can classify 3-5 human motions with the accuracy rate of 63.8-95.7 percent, and it can classify the human motions regardless of frequency band. In order to confirm that the human motion classification using radio signal strength can be used in practice, the applicability of the classification system was evaluated by WBAN measurement data.

Up to now, broadband THz time-domain system has been developed and widely used for THz inspection system; however for many THz devices for THz band wireless communication, narrow-band system would be preferred rather than typical broadband system. In this work we established a narrowband and time-domain THz radiation and detection system and characterized uncooled microbolometer-based THz imagers using that system. The central frequency of generated narrowband THz wave was 850 GHz. This system enables simultaneous measurement of pulse energy and waveform of THz pulse using a superconducting transition edge sensor for measuring energy and electro-optic sampling for measuring THz waveform. We used this system to evaluate the performance of uncooled THz imagers; IRV-T0831 and T0832 from NEC. Noise equivalent power (NEP) of approximately 0.22 pW/Hz1/2 was achieved in case of T0832 at less than 1 THz which is lower than NEP value of previous reports.

A narrowband interference (NBI) estimation and mitigation method based on compressive sensing (CS) for communication systems with repeated training sequences is investigated in this letter. The proposed CS-based differential measuring method is performed through the differential operation on the inter-block-interference-free regions of the received adjacent training sequences. The sparse NBI signal can be accurately recovered from a time-domain measurement vector of small size under the CS framework, without requiring channel information or dedicated resources. Theoretical analysis and simulation results show that the proposed method is robust to NBI under multi-path fading channels.

A wideband on-body antenna for a wireless body area network for an Industrial, Scientific, and Medical band is proposed. A wideband characteristic is achieved by combining two zeroth-order resonance (ZOR) modes at adjacent frequencies by controlling the value of the shunt capacitance. The size of the proposed antenna is 0.072λ0 × 0.33λ0, and the measured 10-dB return loss bandwidth is 340MHz (14.3%). In addition, the resonance frequencies operating in the ZOR mode are insensitive to the effects of the human body by virtue of the ZOR characteristic.

In this paper, we investigate the impact of different sub-band spreading bandwidth (SSBW) on a direct sequence (DS) multiband (MB) ultra wideband (UWB) system in multipath and narrowband interference over realistic UWB channel models based on actual measurements. As an approach to effectively mitigate multipath and narrowband interference, the DS-MB-UWB system employs multiple sub-bands instead of a wide single band for data transmission. By using spreading chips with different duration settings, the SSBW can be manipulated. As a result, it is observed that increasing SSBW does not always improve system performance. Optimum SSBW values exist and are found to vary in accordance to different operating parameters such as the number of sub-bands and types of propagation channel model. Additionally, we have also found that system performance in the presence of narrowband interference is heavily dependent on the number of employed sub-bands.

In this study, we propose a cooperative sensing with distributed pre-detection for gathering sensing information on shared primary system. We have proposed a system that gathers multiple sensing information by using the orthogonal narrowband signal; the system is called the orthogonal frequency-based sensing information gathering (OF-SIG) method. By using this method, sensing information from multiple secondary nodes can be gathered from the surrounding secondary nodes simultaneously by using the orthogonal narrowband signals. The advantage of this method is that the interference from each node is small because a narrowband tone signal is transmitted from each node. Therefore, if appropriate power and transmission control are applied at the surrounding nodes, the sensing information can be gathered in the same spectrum as the primary system. To avoid interference with the primary receiver, we propose a cooperative sensing with distributed pre-detection for gathering sensing information in each node by limiting sensing node power. In the proposed method, the number of sensing information transmitting nodes depends on the pre-detection ability of the individual sensing at each node. Then the secondary node can increase the transmit power by improving the sensing detection ability, and the secondary node can gather the sensing information from the surrounding secondary nodes which are located more far by redesign the transmit power of the secondary nodes. Here, we design the secondary transmit power based on OF-SIG while considering the aggregated interference from multiple sensing nodes and individual sensing ability. Finally we confirm the performance of the cooperative sensing of the proposed method through computer simulation.

In this letter, a timing synchronization scheme is proposed for cooperative WBAN which can be utilized in wireless medical telemetry systems. The approach efficiently exploits the cyclic structure of a presented preamble in order to effectively separate the superposition of cooperative signals. Then, each timing-offset and each channel parameter are estimated in the separated signal. The proposed scheme effectively recovers the original data based on the timing-offset estimates and the channel estimates. The simulation results reveal the excellent performance of the suggested method in terms of MSE and PER.

In this paper, the performance of a low duty factor (DF) hybrid direct sequence (DS) multiband (MB)-pulsed ultra wideband (UWB) system is evaluated over realistic propagation channels to highlight its capability of interference mitigation. The interference mitigation techniques incorporated in the DS-MB-UWB system is a novel design that includes the utilization of the frequency-agile multiple sub-band configuration and the coexistence-friendly low DF signaling. The system design consists of a Rake type receiver over multipath and multi-user channel in the presence of a coexisting narrowband interferer. The propagation channels are modeled based on actual measurement data. Firstly, by suppressing the power in the particular sub-band coexisting with the narrowband signal, performance degradation due to narrowband interference can be improved. It is observed that by fully suppressing the sub-band affected by the narrowband signal, a typical 1-digit performance improvement (e.g. BER improves from 10-3 to 10-4) can be achieved. Secondly, by employing lower DF signaling, self interference (SI) and multi-user interference (MUI) can be mitigated. It is found that a typical 3 dB improvement is achieved by reducing the DF from 0.5 to 0.04. Together, the sub-band power suppression and low DF signaling are shown to be effective mitigation techniques against environment with the presence of SI, MUI and narrowband interference.

This paper proposes a microstrip patch antenna for 2.45 GHz Industrial Scientific Medical (ISM) band Wireless Body Area Network (WBAN) applications. To enhance the front-to-back ratio (F/B) and specific absorption rate (SAR), an electrically coupled LC resonator is introduced. The overall dimensions of the proposed antenna are 54 mm45 mm2.4 mm and it has a gain of over 1 dBi for the entire 2.45 GHz ISM band. The proposed antenna has an enhanced F/B ratio and specific absorption rate, compared with those of a conventional patch antenna.

The localization algorithm based on the double-thresholding (LAD) method was originally proposed for detecting and localizing narrowband (NB) signals with respect to the search bandwidth. Its weakness is that the localized signal is often split into several parts, especially when the signal-to-noise ratio (SNR) is low. This may lead to the illusion of unoccupied frequencies in the middle of the signals. In this paper, an extension of the LAD method, namely the two-dimensional LAD (2-D LAD), is proposed to solve that problem. In addition to offering low computational complexity, the proposed method is able to operate at lower SNR values than the original 1-D LAD method.

Network life time and hence device life time is one of the fundamental metrics in wireless body area networks (WBAN). To prolong it, especially those of implanted sensors, each node must conserve its energy as much as possible. While a variety of wake-up/sleep mechanisms have been proposed, the wake-up radio potentially serves as a vehicle to introduce vulnerabilities and attacks to WBAN, eventually resulting in its malfunctions. In this paper, we propose a novel secure wake-up scheme, in which a wake-up authentication code (WAC) is employed to ensure that a BAN Node (BN) is woken up by the correct BAN Network Controller (BNC) rather than unintended users or malicious attackers. The scheme is thus particularly implemented by a two-radio architecture. We show that our scheme provides higher security while consuming less energy than the existing schemes.

This paper provides an overview of CSEMs FM-UWB PHY-MAC proposal to IEEE802.15.6, Task Group 6, Body Area Networks. The proposed solution provides for an ultra low power, yet robust and reliable solution for low data rate medical BAN. The paper examines the key features and performance aspects of the proposal.

An implantable WBAN path-loss model for a capsule endoscopy which is used for examining digestive organs, is developed by conducting simulations and experiments. First, we performed FDTD simulations on implant WBAN propagation by using a numerical human model. Second, we performed FDTD simulations on a vessel that represents the human body. Third, we performed experiments using a vessel of the same dimensions as that used in the simulations. On the basis of the results of these simulations and experiments, we proposed the gradient and intercept parameters of the simple path-loss in-body propagation model.

In this paper, we propose a novel method for gathering sensing information by using an orthogonal narrowband signal for cooperative sensing in cognitive radio. It is desirable to improve the spectrum sensing performance by countering the locality effect of a wireless channel; cooperative sensing by using multiple inputs of sensing information from the surrounding sensing nodes has attracted attention. Cooperative sensing requires that sensing information be gathered at the master node for determining the existence of a primary signal. If the used information gathering method leads to redundancies, the total capacity of the secondary networks is not improved. In this paper, we propose a novel method for gathering sensing information that maps the sensing information to the orthogonal narrowband signal to achieve simultaneous sensing information gathering at the master node. In this method, the sensing information is mapped to an orthogonal subcarrier signal of an orthogonal frequency division multiplexing (OFDM) structure to reduce the frequency resource required for sensing information gathering. The orthogonal signals are transmitted simultaneously from multiple sensing nodes. This paper evaluates the performance of the proposed information gathering method and confirms its effectiveness.

This paper proposes a hybrid multiband (MB) ultra wideband (UWB) system with direct sequence (DS) spreading. The theoretical error analysis for the DS-MB-UWB multiple access system with Rake receiver in the presence of multipath and narrowband interference is developed. The developed theoretical framework models the multiple access interference (MAI), multipath interference (MI) and narrowband interference for the designed UWB system. It is shown that the system error performance corresponding to the combining effects of these interference can be accurately modeled and calculated. Monte Carlo simulation results are provided to validate the accuracy of the model. Additionally, it is found that narrowband interference can be mitigated effectively in the multiband UWB system by suppressing the particular UWB sub-band co-existing with the interfering narrowband signal. A typical improvement of 5 dB can be achieved with 75% sub-band power suppression. On the other hand, suppression of UWB sub-band is also found to decrease frequency diversity, thus facilitating the increase of MAI. In this paper, the developed model is utilized to determine the parameters that optimize the UWB system performance by minimizing the effective interference.

The average age of population is predicted to be raised universally but the number of nursing staff is not increasing at the same rate. This leads us to the situation where, e.g., we have too many patients for one nurse. On the other hand, sparse population in some regions, such as Northern or Eastern Finland, causes a severe problem that doctors are far away from patient. In this paper, we summarize the possibilities and applications that utilize wireless technologies in healthcare sector and which can be useful in nursing activities. The use of new innovations is one way to solve the problems that are based on the expected lack of professional staff in the future. Despite of the very natural hospital link, the developed technical solutions have applications outside hospital. Remote care of aging people and other special groups need to be done daily and almost real-time. Keeping people home instead of hospital is one way to decrease the entire care costs. In addition to the obvious human context, we derive some other applications where we can benefit wireless nursing and remote sensing techniques.