On the Accurate Performance Evaluation of the LTE-A Random Access Procedure and the Access Class Barring Scheme
TL;DR: This paper presents an analytical model for the performance evaluation of the LTE-A RA procedure that incorporates the access class barring (ACB) scheme, which can be easily adapted to incorporate modifications of network parameters and/or extensions to the LTE -A system.
Abstract: The performance evaluation of the random access (RA) in LTE-A has recently become a major research topic as these networks are expected to play a major role in future 5G networks. Up to now, the key performance indicators (KPIs) of the RA in LTE-A have been obtained either by performing a large number of simulations or by means of analytic models that, oftentimes, sacrifice precision in exchange for simplicity. In this paper, we present an analytical model for the performance evaluation of the LTE-A RA procedure that incorporates the access class barring (ACB) scheme. By means of this model, each and every one of the KPIs suggested by the 3GPP can be obtained with minimal error when compared with results obtained by simulation. To the best of our knowledge, this paper presents the most accurate analytical model, which can be easily adapted to incorporate modifications of network parameters and/or extensions to the LTE-A system. In addition, our model of the ACB scheme can be easily incorporated to other analytic models of similar nature without further modifications.
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TL;DR: In this article, the authors present a possibility to use the federated reinforcement learning (FRL) technique, which is one of the ML techniques, for 5G NR URLLC requirements and summarizes the corresponding achievements.
Abstract: The tactile internet (TI) is believed to be the prospective advancement of the internet of things (IoT), comprising human-to-machine and machine-to-machine communication. TI focuses on enabling real-time interactive techniques with a portfolio of engineering, social, and commercial use cases. For this purpose, the prospective $5^{th}$ generation (5G) technology focuses on achieving ultra-reliable low latency communication (URLLC) services. TI applications require an extraordinary degree of reliability and latency. The $3^{rd}$ generation partnership project (3GPP) defines that URLLC is expected to provide 99.99% reliability of a single transmission of 32 bytes packet with a latency of less than one millisecond. 3GPP proposes to include an adjustable orthogonal frequency division multiplexing (OFDM) technique, called 5G new radio (5G NR), as a new radio access technology (RAT). Whereas, with the emergence of a novel physical layer RAT, the need for the design for prospective next-generation technologies arises, especially with the focus of network intelligence. In such situations, machine learning (ML) techniques are expected to be essential to assist in designing intelligent network resource allocation protocols for 5G NR URLLC requirements. Therefore, in this survey, we present a possibility to use the federated reinforcement learning (FRL) technique, which is one of the ML techniques, for 5G NR URLLC requirements and summarizes the corresponding achievements for URLLC. We provide a comprehensive discussion of MAC layer channel access mechanisms that enable URLLC in 5G NR for TI. Besides, we identify seven very critical future use cases of FRL as potential enablers for URLLC in 5G NR.
62 citations
TL;DR: A closed-form expression and an efficient recursion to obtain this joint PDF are derived and the results validate the effectiveness of the recursive formulation and show that its computational cost is considerably lower than that of other related approaches.
Abstract: The deployment of machine-type communications (MTC) together with cellular networks has a great potential to create the ubiquitous Internet-of-Things environment. Nevertheless, the simultaneous activation of a large number of MTC devices (named UEs herein) is a situation difficult to manage at the evolved Node B (eNB). The knowledge of the joint probability distribution function (PDF) of the number of successful and collided access requests within a random access opportunity (RAO) is a crucial piece of information for contriving congestion control schemes. A closed-form expression and an efficient recursion to obtain this joint PDF are derived in this paper. Furthermore, we exploit this PDF to design estimators of the number of contending UEs in an RAO. Our numerical results validate the effectiveness of our recursive formulation and show that its computational cost is considerably lower than that of other related approaches. In addition, our estimators can be used by the eNBs to implement highly efficient congestion control methods.
31 citations
Cites background from "On the Accurate Performance Evaluat..."
...As it will be described in Section IV-B, the maximum number of contending UEs in highly congested scenarios and with no congestion control in place has been observed to be in the order of a few hundreds [8], [9]....
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TL;DR: A novel classification for the current Random Access (RA) techniques that have been proposed for M2M communications in LTE networks is introduced, and an analytical comparison has been provided among the different techniques according to the parameters for each approach.
Abstract: Machine-to-machine (M2M) communications refer to the autonomous interaction between connected devices without the human intervention. Recently, the Third-Generation Partnership Project (3GPP) introduced the Long-Term Evolution (LTE) and Long-Term Evolution-Advanced (LTE-A) as the improved version of the fourth-generation (4G) cellular networks. LTE/LTE-A networks have been considered an appropriate infrastructure for implementing M2M communications. However, the LTE/LTE-A networks were originally introduced for human-to-human (H2H) communications which have different characteristics from M2M communications. Thus, the LTE/LTE-A networks must be adapted to support the special characteristics of M2M communications. This work provides a comprehensive review of M2M communications over LTE networks, including M2M architectures, LTE structure, deployment challenges, and access control requirements. Moreover, this work introduces a novel classification for the current Random Access (RA) techniques that have been proposed for M2M communications in LTE networks. According to the main targeted objective, the current RA techniques are classified into three categories: massive access control techniques, energy efficiency techniques, and performance improvement techniques. Each category is further divided into two subcategories, and the relevant RA techniques are presented for each category. Furthermore, an analytical comparison has been provided among the different techniques according to the parameters for each approach. This work can be considered a good starting point for those who are interested in RA techniques for M2M communications over LTE/LTE-A networks.
27 citations
Cites methods from "On the Accurate Performance Evaluat..."
...For example, an accurate analytical model has been introduced to evaluate the ACB approach in LTE-A networks [51]....
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TL;DR: This paper promotes the use of a mechanism called Distributed Queueing (DQ), aided by a MAC-layer load estimation technique, to effectively resolve contentions between the MTDs to improve delay performance with minimal impacts to LTE access procedure and air interface.
Abstract: Thanks to their ubiquitous coverage, Long-Term Evolution (LTE) networks are considered the most potential enabler for massive Machine-Type Communications (mMTC) service in fifth-generation (5G) context. LTE standard, however, was not designed for mMTC and scenarios where the massive Machine-Type Devices (MTDs) population try to access a network over a short period may overload the Random Access CHannel (RACH). Furthermore, there is no mechanism to prioritize urgent MTDs in such overload situation. The baseline Access Class Barring (B-ACB) scheme is thus adopted by the 3GPP to address both issues at a substantial cost of access delay. This paper follows a different approach and proposes a complete solution to the two main issues of cellular mMTC. We promote the use of a mechanism called Distributed Queueing (DQ), aided by a MAC-layer load estimation technique, to effectively resolve contentions between the MTDs to improve delay performance with minimal impacts to LTE access procedure and air interface. Then, by exploiting information related to congestion level from the DQ process, a dynamic access prioritization scheme can be realized without additional signaling overhead. Computer simulation under an mMTC-oriented traffic model shows that our framework outperforms the B-ACB in terms of both access delay and energy consumption when all devices are of equal importance. On the other hand, when devices of different priorities coexist, our framework with proper tuning also offers lower delay for all classes and lower overall energy consumption compared to both the baseline and a dynamic ACB solutions in massive bursty access scenarios.
25 citations
Cites methods from "On the Accurate Performance Evaluat..."
...ACB has been shown via both computer simulation [7] and theoretical means [8] to greatly improve access success probability of the MTDs under massive access....
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...tion [6], LTE technology as is may not be suitable for mMTC as suggested by studies from both literature [7], [8] and standardization organizations [9]....
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TL;DR: This paper proposes to combine binary countdown contention resolution (BCCR) with the state-of-the-art access class barring (ACB) and applies a framework for treating RA as a bi-objective optimization, minimizing the resource consumption and maximizing the throughput of the procedure in every contention round.
Abstract: Massive connectivity for Internet of Things applications is expected to challenge the way access reservation protocols are designed in 5G networks. Since the number of devices and their density are envisioned to be orders of magnitude larger, state-of-the-art access reservation, random access (RA) procedure, might be a bottleneck for end-to-end delay. This would be especially challenging for burst arrival scenarios: semi-synchronous triggering of a large number of devices due to a common event (blackout, emergency alarm, etc.). In this paper, to improve RA procedure scalability, we propose to combine binary countdown contention resolution (BCCR) with the state-of-the-art access class barring (ACB). We present a joint analysis of ACB and BCCR and apply a framework for treating RA as a bi-objective optimization, minimizing the resource consumption and maximizing the throughput of the procedure in every contention round. We use this framework to devise dynamic load-adaptive algorithm and simulatively illustrate that the proposed algorithm reduces the burst resolution delay while consuming less resources compared to the state-of-the-art techniques.
22 citations
Cites background from "On the Accurate Performance Evaluat..."
...It has been shown that, in the current networks, the collision feedback as well as broadcast periodicity might exceed PRACH slot duration [17], [21]....
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...Detailed performance model of the standardized ACB has been proposed in [21]....
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References
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TL;DR: A survey of the alternatives that have been proposed over the last years to improve the operation of the random access channel of LTE and LTE-A is provided, identifying strengths and weaknesses of each one of them, while drawing future trends to steer the efforts over the same shooting line.
Abstract: The 3GPP has raised the need to revisit the design of next generations of cellular networks in order to make them capable and efficient to provide M2M services. One of the key challenges that has been identified is the need to enhance the operation of the random access channel of LTE and LTE-A. The current mechanism to request access to the system is known to suffer from congestion and overloading in the presence of a huge number of devices. For this reason, different research groups around the globe are working towards the design of more efficient ways of managing the access to these networks in such circumstances. This paper aims to provide a survey of the alternatives that have been proposed over the last years to improve the operation of the random access channel of LTE and LTE-A. A comprehensive discussion of the different alternatives is provided, identifying strengths and weaknesses of each one of them, while drawing future trends to steer the efforts over the same shooting line. In addition, while existing literature has been focused on the performance in terms of delay, the energy efficiency of the access mechanism of LTE will play a key role in the deployment of M2M networks. For this reason, a comprehensive performance evaluation of the energy efficiency of the random access mechanism of LTE is provided in this paper. The aim of this computer-based simulation study is to set a baseline performance upon which new and more energy-efficient mechanisms can be designed in the near future.
571 citations
"On the Accurate Performance Evaluat..." refers background in this paper
...Specifically, the SystemInformationBlockType2 (SIB2) includes, among other parameters, the periodicity of the time/frequency resources in which preamble transmissions are allowed (random access opportunities, RAOs) [4], [10], [26], [30]....
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...While the data packets sent by these UEs are small in size, the large number of access requests may exceed the signaling capabilities of the eNBs, which leads to severe network congestion and to the loss of potentially critical information [9], [10]....
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TL;DR: The article focuses on two important aspects of MTC devices, currently discussed in 3GPP as part of its Release 10.0, which are subscription control and network congestion/overload control.
Abstract: With a wide range of potential applications, Machine Type Communication (MTC) or Machine to Machine (M2M) communication is gaining a tremendous interest among mobile network operators, equipment vendors, MTC specialist companies, and research bodies. To facilitate convergence among these different stakeholders, different standardization groups started working on MTC. This article introduces briefly some of the relevant activities, with a focus on those related to the 3rd Generation Partnership Project (3GPP). The article focuses on two important aspects of MTC devices, currently discussed in 3GPP as part of its Release 10. They are subscription control and network congestion/overload control. For the latter, a new solution based on bulk signaling handling is proposed.
392 citations
TL;DR: This paper presents architectural enhancements for providing M2M services in 3GPP LTE/LTE-A networks and reviews the features and requirements of M1M applications, and identifies the issues on diverse random access overload control to avoid congestion caused by random channel access of M 2M devices.
Abstract: Machine-to-machine (M2M) communication is an emerging technology to provide ubiquitous connectivity among devices without human intervention. The cellular networks are considered a ready-to-use infrastructure to implement M2M communications. However, M2M communications over cellular pose significant challenges to cellular networks due to different data transactions, diverse applications, and a large number of connections. To support such a large number of devices, M2M system architecture should be extremely power and spectrum efficient. In this paper, we provide a comprehensive survey on M2M communications in the context of the Third-Generation Partnership Project (3GPP) Long-Term Evolution (LTE) and Long-Term Evolution-Advanced (LTE-A). More specifically, this paper presents architectural enhancements for providing M2M services in 3GPP LTE/LTE-A networks and reviews the features and requirements of M2M applications. In addition, the signal overheads and various quality-of-service (QoS) requirements in M2M communications also deserve our attention. We address M2M challenges over 3GPP LTE/LTE-A and also identify the issues on diverse random access overload control to avoid congestion caused by random channel access of M2M devices. Different application scenarios are considered to illustrate futuristic M2M applications. Finally, we present possible enabling technologies and point out the directions for M2M communications research.
344 citations
"On the Accurate Performance Evaluat..." refers background in this paper
...In the near future, M2M will enable a myriad of new applications, but presents several design challenges that must be overcome in order to provide an adequate QoS [4]–[7]....
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TL;DR: The main challenges raised by the M2M vision are described, focusing in particular on the problems related to the support of massive MTD access in current cellular communication systems and the most common approaches proposed in the literature are analyzed.
268 citations
"On the Accurate Performance Evaluat..." refers background in this paper
...In the near future, M2M will enable a myriad of new applications, but presents several design challenges that must be overcome in order to provide an adequate QoS [4]–[7]....
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...Specifically, the SystemInformationBlockType2 (SIB2) includes, among other parameters, the periodicity of the time/frequency resources in which preamble transmissions are allowed (random access opportunities, RAOs) [4], [10], [26], [30]....
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...Therefore, it is not efficient at handling the highly-synchronized traffic that is generated by a large number of UEs in M2M applications; hence, severe congestion is likely to occur under these conditions [4]–[8]....
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TL;DR: The problem of RACH overload is studied, several types of RAN-level contention resolution methods are surveyed, and the current development of CN (core network) overload mechanisms in 3GPP LTE are introduced.
Abstract: As Machine-Type-Communications (MTC) continues to burgeon rapidly, a comprehensive study on overload control approach to manage the data and signaling traffic from massive MTC devices is required. In this work, we study the problem of RACH overload, survey several types of RAN-level contention resolution methods, and introduce the current development of CN (core network) overload mechanisms in 3GPP LTE. Additionally, we simulate and compare different methods and offer further observations on the solution design.
169 citations
"On the Accurate Performance Evaluat..." refers background in this paper
...As such, LTE-A networks present the best solution for the interconnection of devices (known as user equipments, UEs) and will serve as a foundation for the future development of the IoT and 5G systems [3]–[5]....
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