Non-contact measurement of vital signs is an important issue in modern healthcare, aimed at enhancing patient comfort and convenience. Achieving sufficient measurement distance and adaptability to patient movement is essential for effectiveness. Current research covers measurement ranges between 1 and 3.5 meters. This study introduces a novel multifeature transformer-based super-resolution model. By inputting and encoding low-resolution sequences of distance, phase, and phase variation rates, the model upsamples these sequences, generating additional sample points and transforming the lowresolution data into high-resolution sequences. This process improves the quality and range of FMCW radar measurements by increasing the sample points, enabling the model to extract vital sign information from low-resolution sequences and produce accurate results. From the generated high-resolution sequences, vital signs such as heart rate and respiration are then extracted. Experimental results show that, at a distance of 5 meters, the system achieves 87.3 accuracy for heart rate and 89.1 accuracy for respiration in a walking scenario, outperforming existing solutions by 8.6 % and 6.5 %, respectively.

Due to the increasing severity of the COVID-19 pandemic, timely screening and diagnosis of infections are essential. Since cough is a common symptom of COVID-19, an AI-assisted cough classification scheme is designed in this paper to diagnose COVID-19 infection. To reduce the labeling efforts by human experts, a semi-supervised learning with voting scheme using a triple-classifier model is proposed for the COVID-19 cough classification. This work aims to improve the accuracy of the classification. Initially, the data pre-processing scheme is executed by performing data cleaning, resampling, and data enhancement so as to improve the audio quality before training. The pre-training scheme is then performed by using a few numbers of COVID-19 cough data with labeling. Then we modify a well-known self-supervised learning model, SimCLR, to a semi-supervised learning-based SimCLR-like model, which uses three different loss functions to fine-tune three training models for cough classification. Finally, a voting scheme is performed based on the classification results of the three cough classifiers so as to enhance the accuracy of the cough classification for COVID-19. The experiment results illustrate that the proposed scheme can achieve 85% accuracy, which outperforms the existing semi-supervised learning-based classification schemes.

Mobile data offloading has become an important issue for mobile cellular network in recent years. Existing energy-aware data offloading scheme for mobile cellular network makes the offloading decision only according to the current local information of the user equipment (UE) and thus the UE cannot switch to a more efficient way to offload even other UEs have released their transmission resources later on. Hence, in this paper, a centralized offloading scheme based on cloud radio access networks (C-RAN) is proposed so as to make the offloading more efficient. The C-RAN based centralized offloading scheme considers all the situation of UEs of a baseband unit (BBU) at the same time and thus the BBU can do a better offloading decision for those UEs. At the beginning, each UE, who needs offloading, sends an offloading request to the BBU. When there is any UE released the transmission resource, the corresponding BBU will try to fulfill the pending offloading requests of the UEs. The corresponding BBU considers the pending UEs' transmission rate and energy consumption of the cellular network as well as the Wi-Fi network, and then makes offloading decisions for those UEs so as to save more energy and achieve higher throughput at the macroscopic level. Extensive simulations have been conducted to illustrate that the proposed energy-aware data offloading scheme can reduce the energy consumption and turnaround time, and enhance the transmission throughput.

In vehicular ad hoc networks, vehicles may use a routing protocol to inform emergent events, for example, car accidents or traffic jams. Hence, many of the researchers are focused on minimizing the end-to-end delay of the routing protocol. However, some applications, for example, email or ftp, are not time critical, and radio spectrum is a limited resource. Hence, delay-bounded routing protocol, whose goal is to deliver messages to the destination within user-defined delay and minimize the usage of radio, has become an important issue. The delay-bounded routing protocols deliver message to the destination by the hybrid of data muling carried by the vehicle and forwarding transmitted through radio. When the available time is enough, the message will be delivered by muling; otherwise, it will be delivered by forwarding. However, in an urban area, there are many traffic lights, which may greatly affect the performance of the delay-bounded routing protocols. Existing works do not consider the effect of traffic lights, and hence, it may adopt an improper delivery strategy and thus wastes much available time. To improve previous works, we propose a novel delay-bounded routing protocol, which has considered the effect of traffic lights. Whenever a vehicle passes an intersection, it will gather the information of the traffic light and traffic load of the next road section, and thus, it can make a more accurate prediction and adopt a more proper strategy to deliver message. Simulation results show that the proposed protocol can make a better usage of the available time and uses less radio resource to deliver the message in time. Copyright © 2013 John Wiley & Sons, Ltd.

A new non-IP networking technology, called as named data networking (NDN), is an emerging research topic for the future Internet. In this paper, we propose a pipe-assisted mobility protocol in NDN networks. The proposed mobility protocol is constructed based on a new proposed name-based routing scheme by utilizing a pipe technique. A new name-based routing protocol is developed by constructing a pipe from a consumer to a producer in NDN networks. With the assistance of the constructed pipe, a pipe-assisted producer mobility protocol is proposed. When a mobile producer enters a new domain, a pipe-based pre-route with the maximum popular levels is built to increase the successful probability of discovering a new path from the producer to the consumer. Extensive simulations illustrate that the proposed pipe-assisted mobility protocol significantly reduces the packet loss rate.

Most of the researches pay attention to minimize the end-to-end delay rather than reduce the usage of radio. However, some information is not urgent and radio is a valuable and limited resource. Recently, delay-bounded routing protocol has become a popular issue, whose goal is to deliver messages to the destination within user-defined delay and minimize the usage of radio. To decrease the burden on the environment and save energy, the hybrid-solar vehicle is one of the most prominent solutions. The existing delay-bounded routing protocols do not consider the charge and the energy expenditure factors and only choose the path with the least forwarding times. To improve previous works, we propose a mechanism based on a cost function, which includes forwarding times and power gain, to choose a minimum cost path. Besides, we propose a novel mechanism to deliver message to the destination by the hybrid of data muling (carried by the vehicle) and forwarding (transmitted through radio). In the existing protocol, when the remaining time is not enough the vehicle should forward the message by radio and when the remaining time is enough the vehicle should carry the message by itself. However, forwarding message by radio consumes more energy and hence the energy factor should be added into the consideration. The proposed protocol contains two schemes: the greedy and centralized schemes. In the centralized scheme, the information such as the solar illumination, length of each road segment, and the average velocity of the vehicles on each road segment are collected and then the dynamic programming is used to find the least cost routing path. In the greedy scheme, it only has the knowledge of the average velocity, the solar illumination and the length of all the possible next road segments to choose the next road segment with the least cost. Simulation results illustrate that the proposed routing protocol can save more energy than existing protocols.

Routing protocols for vehicular ad hoc networks (VANETs) have attracted a lot of attention recently. Most of the researches emphasize on minimizing the end-to-end delay without paying attention to reducing the usage of radio. This paper focuses on delay-bounded routing, whose goal is to deliver messages to the destination within user-defined delay and to minimize the usage of radio because radio spectrum is a limited resource. The messages can be delivered to the destination by the hybrid of data muling (carried by the vehicle) and forwarding (transmitted through radio). In the existing protocol, a vehicle may only switch the delivery strategy (muling or forwarding) at an intersection according to the available time of the next road segment, which is between the current intersection and the next intersection. To improve previous works, our protocol uses linear regression to predict the available time and the traveling distance, and thus, the vehicle can switch to a proper delivery strategy at a proper moment and can reduce the number of relays by radio. Our protocol contains two schemes: the greedy and centralized schemes. The greedy scheme uses only the current sampling data to predict the available time and decide when to switch the delivery strategy, whereas the centralized scheme uses the global statistical information to choose a minimum-cost path. Simulation results justify the efficiency of the proposed protocol. Copyright © 2011 John Wiley & Sons, Ltd.

The IPv6 over Low power Wireless Personal Area Network (6LoWPAN) has attracted lots of attention recently because it can be used for the communications of Internet of things (IoT). In this paper, the concept of group-based network roaming in Proxy Mobile IPv6 (PMIPv6) domain is considered in the 6LoWPAN-based wireless body area networks. PMIPv6 is a standard to manage the network-based mobility in all-IP wireless network. However, it does not perform well in group-based body area networks. To further reduce the handoff delay and signaling cost, an enhanced group mobility scheme is proposed in this paper to reduce the number of control messages, including Router Solicitation (RS) and Router Advertisement (RA) messages as opposed to the group-based PMIPv6 protocol. Simulation results illustrate that the proposed handoff scheme can reduce the handoff delay and signaling cost. The packet loss ratio and the overhead can also be reduced.

Routing protocols for vehicular ad hoc networks (VANETs) have attracted a lot of attention recently. Most of the researches emphasize on minimizing the end-to-end delay without paying attention to reducing the usage of radio. This paper focuses on delay-bounded routing, whose goal is to deliver messages to the destination within user-defined delay and minimize the usage of radio. The messages can be delivered to the destination by the hybrid of data muling (carried by the vehicle) and forwarding (transmitted through radio). In the existing protocol, a vehicle may only switch the delivery strategy (muling or forwarding) at an intersection according to the available time of the next block. To improve previous works, our protocol uses linear regression to predict the available time and the travel distance and thus the vehicle can switch to a proper delivery strategy at a proper moment and can reduce the number of relays by radio. Our protocol contains two schemes: the greedy and centralized schemes. The greedy scheme uses only the local vehicle's speed to predict the available time and decide when to switch the delivery strategy; while the centralized scheme uses the global statistical information to make the decision. Simulation results justify the efficiency of the proposed protocol.

The goal of the network mobility (NEMO) management is to effectively reduce the complexity of handoff procedure and keep the mobile devices connected to the Internet. Vehicle is moving so fast that it may cause the handoff and packet loss problems. Both of the problems will lower down the throughput of the network. To overcome these problems, we propose a novel NEMO protocol for vehicular ad hoc network (VANET). In freeway, since every car is moving in a fixed direction with high moving speed, the car adopting our protocol can acquire IP address from the VANET through vehicle to vehicle communications. The vehicle can rely on the assistance of the front vehicle to execute the pre-handoff procedure or it may acquire its new IP address through multi-hop relays from the car on the lanes of the same or opposite direction and thus reduces the handoff delay and maintain the connectivity to the Internet. Simulation results have shown that the proposed scheme is able to reduce both handoff delay and packet loss rate.

Localization is a fundamental and essential issue for wireless sensor networks (WSNs). Existing localization algorithms can be categorized as either range-based or range-free schemes. Range-based schemes are not suitable for WSNs because of their irregularity of radio propagation and their cost of additional devices. In contrast, range-free schemes do not need to use received signal strength to estimate distances and only need simple and cheap hardware, and are thus more suitable for WSNs. However, existing range-free schemes are too costly and not accurate enough or are not scalable. To improve previous work, we present a fully distributed range-free localization scheme for WSNs. We assume that only a few sensor nodes, called anchors, know their locations, and the remaining (normal) nodes need to estimate their own locations by gathering nearby neighboring information. We propose an improved grid-scan algorithm to find the estimated locations of the normal nodes. Furthermore, we derive a vector-based refinement scheme to improve the accuracy of the estimated locations. Analysis, simulation, and experiment results show that our scheme outperforms the other range-free schemes even when the communication radius is irregular.

Abstract The wireless sensor network (WSN) has attracted lots of attention recently. Broadcast is a fundamental operation for all kinds of networks and it has not been addressed seriously in the WSN. Therefore, we propose two types of power and time efficient broadcasting protocols, namely one‐to‐all and all‐to‐all broadcasting protocols, for five different WSN topologies. Our one‐to‐all broadcasting protocols conserve power and time by choosing as few relay nodes as possible to scatter packets to the whole network. Besides, collisions are carefully handled such that our one‐to‐all broadcasting protocols can achieve 100% reachability. By assigning each node a proper channel, our all‐to‐all broadcasting protocols are collision free and efficient. Numerical evaluation results compare the performance of the five topologies and show that our broadcasting protocols are power and time efficient. Copyright © 2005 John Wiley & Sons, Ltd.

Existing power-saving (PS) protocols for mobile ad hoc networks (MANETs) can be categorized into synchronous and asynchronous ones. The synchronous PS protocol cannot be applied to a multi-hop MANET, because it can cause three problems: clock synchronization; neighbor discovery; network partitioning. Although asynchronous solutions are attractive, the cost is high compared to synchronous protocols. Hosts in asynchronous protocols need to keep awake for a longer time, so as to discover asynchronous PS neighbors. Besides, a broadcast message has to be sent multiple times if a sending host's neighbors wake up asynchronously. To conquer the deficiency of asynchronous PS protocols, we propose several cluster-based semi-asynchronous PS protocols for multi-hop MANETs. The basic idea is to cluster neighboring hosts such that synchronous PS protocols can be adopted within individual clusters, conserving a lot of energy. Two asynchronous schemes are provided in the inter-cluster level, including SNR-probability-based and location-based schemes. Simulation results show that the proposed semi-asynchronous approaches outperform the asynchronous PS protocols when applied to a multi-hop MANET.

The wireless sensor network (WSN) has attracted lots of attention recently. Since the sensor nodes usually have no plug-in power, we have to conserve power so that each sensor node can operate for a longer period of time. Here, we propose power and time efficient broadcasting protocols for four different WSN topologies. Our broadcasting protocols conserve power and time by choosing as few relay nodes as possible to scatter messages to the whole network. Besides, collisions are carefully handled such that our one-to-all broadcast protocols can achieve 100% reachability. Numerical evaluation results compare the performances of the four topologies and show that our broadcasting protocols are power and time efficient.

We investigate the power mode management problem for an IEEE 802.11-based mobile ad hoc network (MANET) that allows mobile hosts to tune to the power-saving (PS) mode. We adopt an asynchronous approach proposed in [Y. C. Tseng et al., (2002)] and correlate this problem to the quorum system concept. We identify a rotation closure property for quorum systems. It is shown that any quorum system that satisfies this property can be translated to an asynchronous power-saving protocol for MANETs. We derive a lower bound for quorum sizes for any quorum system that satisfies the rotation closure property. We identify a group of quorum systems that are optimal or near optimal in terms of quorum sizes, which can be translated to efficient asynchronous power-saving protocols. We also propose a new e-torus quorum system, which can be translated to an adaptive protocol that allows designers to trade hosts' neighbor sensibility for power efficiency.

Abstract Leader election and initialization are two fundamental problems in mobile ad hoc networks (MANETs). The leader can serve as a coordinator in the MANETs and the initialization protocol can assign each host a sequential, unique, and short ID. As we know, no research on initialization for IEEE 802.11‐based MANETs has been done. Here, we propose two contention‐based leader election and initialization protocols for IEEE 802.11‐based single‐hop MANETs. We also provide an efficient approach to evaluate the performance of the proposed protocols, such that the performance can be evaluated in polynomial time. The evaluation results provide a guideline to set the size of the contention window and thus improve the performance of the proposed leader election and initialization protocols. The results can also be used as a guideline to set the size of the contention window for any contention‐based protocol. Simulation results justify that the evaluation results provide a good guideline to set the size of the contention window. Copyright © 2003 John Wiley & Sons, Ltd.

Leader election and initialization are two fundamental problems in mobile ad hoc networks (MANETs). The leader can serve as a coordinator in the MANETs and the initialization protocol can assign each host a unique and short id. We know that none of the research on initialization for IEEE 802.11-based MANETs has been done. Here, we propose two contention-based leader election and initialization protocols for IEEE 802.11-based single-hop MANETs. Simulation results show that our protocols are efficient.

Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of power-saving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multi-hop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and Bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols.