Short-range Communication Devices Research Articles

Dwell time estimation at intersections for improved vehicular micro cloud operations

Edge computing is becoming a major building block of next generation 5G/6G networks. However, infrastructure might not always be available because of slow deployment. At the same time, vehicular networks are becoming a reality now and cars are being equipped with a variety of short-range communication devices. The idea of vehicular micro clouds is to turn cars into (virtual) edge computing infrastructure. One of the challenging questions in this domain is to maintain data within and among such micro clouds. In this paper, we focus on this task and present a novel solution for such data exchange between vehicular micro clouds. For efficient operation, the dwell times of cars in such a micro cloud need to be known or accurately predicted. In an extensive study based on trace data, we investigate the distribution of dwell times of cars at intersections. We make use of this distribution as an input for designing an improved data exchange algorithm. As not all intersections are the same, adding additional variance further benefits the solution. We evaluated our algorithm in different vehicular densities, and we observed that we could maintain data 22–208% longer within the micro clouds using our new algorithm. Overall, our results show that our algorithm clearly outperforms previous solutions.

A Compact Quad-Element UWB-MIMO Antenna System with Parasitic Decoupling Mechanism

This research work proposes a compact four-port multiple-input multiple-output (MIMO) antenna that operates in the whole license free ultra-wideband (UWB) spectrum of 3.1–10.6 GHz. Spatial diversity has been introduced by arranging these antennas in close proximity without developing a strong mutual coupling. Antenna elements are evolved from a conventional rectangular patch antenna whereas a customized decoupling structure is introduced on the back side of the substrate to achieve the desired isolation level. The parasitic decoupling structure consists of different features which are resonant at different frequencies offering a whole UWB coverage. In addition to the decoupling structure a dumbbell shaped stub has also been introduced to the partial ground plane to suppress the mutual coupling. The overall measured isolation among elements is more than 20 dB. Different MIMO performance parameters have also been investigated from the measured results. Whole MIMO system measures 0.41 λo × 0.44 λo at 3.1 GHz. The MIMO system is intended for high data rate and short-range communication devices used in wireless personal area networks.

RETRACTED: A Semi-Hexagonal Array (1×2) Antenna Using Half Mode Substrate Integrated Waveguide for Short Range Communication Devices

This article has been retracted at the request of the Editor-in-Chief due to extended similarites with an unpublished paper, written by other authors, that was submitted (but not yet published) to several other journals and was probably leaked during the review process. The authors of the unpublished paper contacted the Editor-In-Chief with the above claim after the publication of this issue and ETASR has contacted several of the journals mentioned and the investigation resulted in the confirmation of the report. The authors of this paper failed to provide any reasoning regarding the case.

Hiding Yourself Behind Collaborative Users When Using Continuous Location-Based Services

The prosperity of location-based services (LBSs) makes more and more people pay close attention to personal privacy. In order to preserve users privacy, several schemes utilized a trusted third party (TTP) to obfuscate users, but these schemes were suspected as the TTP may become the single point of failure or service performance bottleneck. To alleviate the suspicion, schemes with collaborative users to achieve [Formula: see text]-anonymity were proposed. In these schemes, users equipped with short-range communication devices could communicate with adjacent users to establish an anonymous group. With this group, the user can obfuscate and hide herself behind at least [Formula: see text] other users. However, these schemes are usually more efficient in snapshot services than continuous ones. To cope with the inadequacy, with the help of caching in mobile devices, we propose a query information blocks random exchange and results caching scheme (short for CaQBE). In this scheme, a particular user is hidden behind collaborative users in snapshot service, and then the caches further preserve the privacy in continuous service. In case of the active adversary launching the query correlation attack and the passive adversary launching the impersonation attack, a random collaborative user selection and a random block exchange algorithm are also utilized. Then based on the feature of entropy, a metric to measure the privacy of the user against attacks from the active and passive adversaries is proposed. Finally, security analysis and experimental comparison with other similar schemes further verify the optimal of our scheme in effectiveness of preservation and efficiency of performance.

LTE FDD AND SRD EQUIPMENT COMPATIBILITY IN 2500 MHZ BAND / LTE FDD IR SRD ĮRENGINIŲ SUDERINAMUMAS 2500 MHZ RUOŽE

This paper examines the LTE mobile communication base stations possible interfering effects on short range communication devices operating in ISM frequency band. LTE network is running in 2500–2690 MHz frequency band, where frequency channel distribution is used. Downlink channels are assigned to base stations and formed in 2620–2680 MHz band, uplink channels are assigned to mobile stations and formed in 2500–2560 MHz band. Short range communication devices operate in 2400–2483.5 MHz frequency range. The main problem of this study – the interference probability and magnitude. Real equipment was simulated using two different modelling software systems for investigation of electromagnetic compatibility: ICS Telecom and Seamcat. The modelling results show that LTE BS have minimum or no impact on operation of short range communication devices in ISM frequency band. Nagrinėjamas LTE mobiliojo ryšio bazinių stočių galimas interferencinis poveikis nedidelio veikimo nuotolio įrenginiams. LTE tinklas veikia 2500–2690 MHz dažnių ruože, naudojamas dažninis kanalų dalijimas. Žemynkrypčiai kanalai, priskiriami bazinėms stotims, formuojami 2620–2680 MHz ruože, aukštynkrypčiai kanalai, priskiriami mobiliosioms stotims, formuojami 2500–2560 MHz ruože. Trumpojo veikimo nuotolio įrenginiai veikia 2400–2483,5 MHz dažnių ruože. Pagrindinė šio tyrimo problema – galima interferencija ir jos mastas. Realus įrenginių veikimas modeliuojamas dviejomis skirtingomis programomis, kurios skirtos elektromagnetiniam suderinamumui tirti: ICS Telecom ir Seamcat.

Reactive routing evaluation using modified 802.11a with realistic vehicular mobility

Realistic mobility dynamics and underlying PHY/MAC layer implementation affect real deployment of routing protocols in vehicular ad hoc network (VANET). Currently, dedicated short range communication devices are using wireless access in vehicular environment (WAVE) mode of operation, but now IEEE is standardizing 802.11p WAVE. This work presents an in-depth simulation-based analysis of two reactive routing protocols, i.e., dynamic source routing (DSR) and ad hoc on-demand distance vector (AODV) with modified IEEE 802.11a PHY/MAC layers (comparable to 802.11p) in modified VANET mobility models (freeway, stop sign, and traffic sign) in terms of load, throughput, delay, number of hops, and retransmission attempts. Results obtained using OPNET simulator show that in urban/highway mobility scenarios, AODV’s performance with forthcoming 802.11p at high bit rate would be better than DSR in terms of high throughput, less delay, and retransmission attempts. Moreover, this comprehensive evaluation will assist to address challenges associated with future deployment of routing protocols integrated upon devices with upcoming IEEE 802.11p, concerning specific macro-/micro-mobility scenarios.

Practical channel state aware and cooperative packet scheduling disciplines for coordinating colocated Bluetooth and IEEE 802.11b devices

Attempts to satisfy the demand for ubiquitous communications have resulted in a proliferation of hand-held short range communication devices based on the ISM (Industrial, Scientific, Medical) band technologies, most notably Bluetooth and IEEE 802.11b. However, coexistence between Bluetooth and IEEE 802.11b has become a critical issue that could severely hinder the performance achieved by user devices. In this study we performed a detailed implementation of a Linux based network access point (NAP), in which Bluetooth and IEEE 802.11b interfaces are colocated. Such an NAP is crucial in supporting “hot-spot” systems targeted to serve nomadic users carrying either a Bluetooth or an IEEE 802.11b device. Specifically, the goal of our study is to investigate the efficacy of a software-based interference coordination approach, through a detailed actual implementation so as to identify system issues which are difficult to obtained by simulations. We considered a wide range of common scheduling algorithms as the possible solutions in a Linux environment to estimate the interference effects as viewed from the network layer perspective. Upon our investigation, two wireless scheduling algorithms based on Channel State Independent Fair Queueing (CIFQ) were implemented in Linux to test their empirical performance under this NAP application. Finally, guided by our practical findings, we proposed and implemented two new packet scheduling algorithms in Linux to provide the best trade-offs to colocated Bluetooth and IEEE 802.11b traffics, as well as QoS support for different applications. Our results show that dynamic priorities and cooperative transmissions between Bluetooth and IEEE 802.11b traffic can effectively protect both interfaces from interference. We also compared our proposed scheme with two MAC layer approaches.