1,757 research outputs found
Ultra-Reliable Short Message Cooperative Relaying Protocols under Nakagami-m Fading
In the next few years, the development of wireless communication systems
propel the world into a fully connected society where the Machine-type
Communications (MTC) plays a substantial role as key enabler in the future
cellular systems. MTC is categorized into mMTC and uMTC, where mMTC provides
the connectivity to massive number of devices while uMTC is related to low
latency and ultra-high reliability of the wireless communications. This paper
studies uMTC with incremental relaying technique, where the source and relay
collaborate to transfer the message to a destination. In this paper, we compare
the performance of two distinct cooperative relaying protocols with the direct
transmission under the finite blocklength (FB) regime. We define the overall
outage probability in each relaying scenario, supposing Nakagami-m fading. We
show that cooperative communication outperforms direct transmission under the
FB regime. In addition, we examine the impact of fading severity and power
allocation factor on the outage probability and the minimum delay required to
meet the ultra-reliable communication requirements. Moreover, we provide the
outage probability in closed form
Cellular, Wide-Area, and Non-Terrestrial IoT: A Survey on 5G Advances and the Road Towards 6G
The next wave of wireless technologies is proliferating in connecting things
among themselves as well as to humans. In the era of the Internet of things
(IoT), billions of sensors, machines, vehicles, drones, and robots will be
connected, making the world around us smarter. The IoT will encompass devices
that must wirelessly communicate a diverse set of data gathered from the
environment for myriad new applications. The ultimate goal is to extract
insights from this data and develop solutions that improve quality of life and
generate new revenue. Providing large-scale, long-lasting, reliable, and near
real-time connectivity is the major challenge in enabling a smart connected
world. This paper provides a comprehensive survey on existing and emerging
communication solutions for serving IoT applications in the context of
cellular, wide-area, as well as non-terrestrial networks. Specifically,
wireless technology enhancements for providing IoT access in fifth-generation
(5G) and beyond cellular networks, and communication networks over the
unlicensed spectrum are presented. Aligned with the main key performance
indicators of 5G and beyond 5G networks, we investigate solutions and standards
that enable energy efficiency, reliability, low latency, and scalability
(connection density) of current and future IoT networks. The solutions include
grant-free access and channel coding for short-packet communications,
non-orthogonal multiple access, and on-device intelligence. Further, a vision
of new paradigm shifts in communication networks in the 2030s is provided, and
the integration of the associated new technologies like artificial
intelligence, non-terrestrial networks, and new spectra is elaborated. Finally,
future research directions toward beyond 5G IoT networks are pointed out.Comment: Submitted for review to IEEE CS&
IEEE 802.15.7-Compliant Ultra-low Latency Relaying VLC System for Safety-Critical ITS
The integration of Visible-Light Communications technology (VLC) in
Intelligent Transportation Systems (ITS) is a very promising platform for a
cost-effective implementation of revolutionary ITS and cooperative ITS
protocols. In this paper, we propose an infrastructure-to-vehicle-to-vehicle
(I2V2V) VLC system for ITS, implementing it through a regular LED traffic light
serving as a transmitter and a digital Active Decodeand- Relay (ADR) stage for
decoding and relaying the received information towards further incoming units.
The proposed VLC system targets the challenging and important case of ultra-low
latency ADR transmission of short packets, as this is needed for emerging
applications of automatic braking, car platooning and other critical automatic
and/or assisted driving applications. The experimental validation of the ADR
VLC chain, as well as a thorough statistical analysis of errors distribution in
the transmission, has been performed for short to medium distances, up to 50
meters. The performances of the designed system are evaluated by measuring the
packet error rate (PER) and latency in the whole ADR transmission chain. Our
analysis shows that our system attains ultra-low, sub-ms latencies at 99.9%
confidence level for PER as high as 5 x 10^-3, yet granting a latency below 10
ms even for distances of 50 m. The demonstrated system prototype is compatible
with IEEE 802.15.7 standard
Relaying in the Internet of Things (IoT): A Survey
The deployment of relays between Internet of Things (IoT) end devices and gateways can improve link quality. In cellular-based IoT, relays have the potential to reduce base station overload. The energy expended in single-hop long-range communication can be reduced if relays listen to transmissions of end devices and forward these observations to gateways. However, incorporating relays into IoT networks faces some challenges. IoT end devices are designed primarily for uplink communication of small-sized observations toward the network; hence, opportunistically using end devices as relays needs a redesign of both the medium access control (MAC) layer protocol of such end devices and possible addition of new communication interfaces. Additionally, the wake-up time of IoT end devices needs to be synchronized with that of the relays. For cellular-based IoT, the possibility of using infrastructure relays exists, and noncellular IoT networks can leverage the presence of mobile devices for relaying, for example, in remote healthcare. However, the latter presents problems of incentivizing relay participation and managing the mobility of relays. Furthermore, although relays can increase the lifetime of IoT networks, deploying relays implies the need for additional batteries to power them. This can erode the energy efficiency gain that relays offer. Therefore, designing relay-assisted IoT networks that provide acceptable trade-offs is key, and this goes beyond adding an extra transmit RF chain to a relay-enabled IoT end device. There has been increasing research interest in IoT relaying, as demonstrated in the available literature. Works that consider these issues are surveyed in this paper to provide insight into the state of the art, provide design insights for network designers and motivate future research directions
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