642 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
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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