While 5G is being rolled out in different parts of the globe, few research groups around the world − such as the Finnish 6G Flagship program − have already started posing the question: What will 6G be? The 6G vision is a data-driven society, enabled by near instant unlimited wireless connectivity. Driven by impetus to provide vertical-specific wireless network solutions, machine type communication encompassing both its mission critical and massive connectivity aspects is foreseen to be an important cornerstone of 6G development. This article presents an over-arching vision for machine type communication in 6G. In this regard, some relevant performance indicators are first anticipated, followed by a presentation of six key enabling technologies.
In this paper, we suggest a power allocation strategy for the Chase Combining Hybrid Automatic Repeat Request (CC-HARQ) protocol with ultra-reliability constraints. The proposed optimal power allocation scheme would allow us to reach any outage probability target in the finite block-length regime. We cast an optimization problem as minimization of the average transmitted power under a given outage probability and maximum transmit power constraint. To solve the problem and attain the closed form solution, we utilize the Karush-Kuhn-Tucker (KKT) conditions. We show that in the finite block-length regime the transmitted power is highly dependent on the number of channel uses. However, as the block size increases, the transmitted power becomes constant. Furthermore, we show that by using the proposed power allocation scheme, we can achieve very large average and sum power gains when compared to the one shot transmission.
Effective capacity (EC) determines the maximum communication rate subject to a particular delay constraint. In this work, we analyze the EC of ultra reliable Machine Type Communication (MTC) networks operating in the finite blocklength (FB) regime. First, we present a closed form approximation for EC in quasi-static Rayleigh fading channels. Our analysis determines the upper bounds for EC and delay constraint when varying transmission power. Finally, we characterize the powerdelay trade-off for fixed EC and propose an optimum power allocation scheme which exploits the asymptotic behavior of EC in the high SNR regime. The results illustrate that the proposed scheme provides significant power saving with a negligible loss in EC.Index Terms-Effective capacity, finite blocklength, ultra reliable communication, optimal power allocation. I. INTRODUCTIONCommunication systems have become everyday use equipments everywhere around us. In these systems, information is commonly conveyed in the form of data bits which are then transformed to coded packets. Packets are then transmitted in noisy mediums which are affected by fading. For a certain communication channel, Shannon capacity determines the attainable rate by which information can be transmitted with almost no error. Conventionally, communication systems are designed based on Shannon theory, which resorts to the transmission of relatively long data packages when there is a large number of channel uses per packet. Machine type communication (MTC) systems ranging from sensor to vehicular networks often have strict delay constraints, where packets are relatively short and required to be transmitted at minimum latency and a high level of reliability (i.e, >99.99%). This is not merely achieved via conventional coding with long blocklength. Meanwhile, ultra reliable communication (URC) has evolved to propose solutions for reliable and low latency communication. The next generations of mobile communication are expected to support such demands via MTC [1]-[3].To achieve minimum latency and ultra reliability as envisioned for real time applications and emerging technologies such as e-health and road safety, these networks communicate on short messages. Transmission of short packets does not M. Shehab, H. Alves, and M. Latva-aho are with Centre for Wireless Communications (CWC), University of Oulu, Finland Email: firstname.lastname@oulu.fi
The current random access (RA) allocation techniques suffer from congestion and high signaling overhead while serving massive machine-type communication (mMTC) applications. To this end, third-generation partnership project introduced the need to use fast uplink grant (FUG) allocation in order to reduce latency and increase reliability for smart Internet of Things (IoT) applications with strict Quality-of-Service constraints. We propose a novel FUG allocation based on support vector machine (SVM). First, machine-type communication (MTC) devices are prioritized using an SVM classifier. Second, a long short-term memory architecture is used for traffic prediction and correction techniques to overcome prediction errors. Both results are used to achieve an efficient resource scheduler in terms of the average latency and total throughput. A coupled Markov modulated Poisson process (CMMPP) traffic model with mixed alarm and regular traffic is applied to compare the proposed FUG allocation to other existing allocation techniques. In addition, an extended traffic model-based CMMPP is used to evaluate the proposed algorithm in a more dense network. We test the proposed scheme using real-time measurement data collected from the Numenta anomaly benchmark (NAB) database. Our simulation results show the proposed model outperforms the existing RA allocation schemes by achieving the highest throughput and the lowest access delay of the order of 1 ms by achieving prediction accuracy of 98 % when serving the target massive and critical MTC applications with a limited number of resources.
This paper analyzes the effective capacity (EC) of delay constrained machine type communication (MTC) networks operating in the finite blocklength (FB) regime. First, we derive a closed-form mathematical approximation for the EC in Rayleigh block fading channels. We characterize the optimum error probability to maximize the concave EC function and study the effect of SINR variations for different delay constraints. Our analysis reveals that SINR variations have less impact on EC for strict delay constrained networks. We present an exemplary scenario for massive MTC access to analyze the interference effect proposing three methods to restore the EC for a certain node which are power control, graceful degradation of delay constraint and joint compensation. Joint compensation combines both power control and graceful degradation of delay constraint, where we perform maximization of an objective function whose parameters are determined according to delay and SINR priorities. Our results show that networks with stringent delay constraints favor power controlled compensation and compensation is generally performed at higher costs for shorter packets.
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