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21 pages, 1138 KiB

Open AccessArticle

QoE Optimization in a Live Cellular Network through RLC Parameter Tuning

by Jessica Mendoza, Isabel de-la-Bandera, David Palacios and Raquel Barco

Sensors 2021, 21(16), 5619; https://doi.org/10.3390/s21165619 - 20 Aug 2021

Cited by 6 | Viewed by 3853

The mobile communication networks sector has experienced a great evolution during the last few years. The emergence of new services as well as the growth in the number of subscribers have motivated the search for new ways to optimize mobile networks. In this way, the objective pursued by optimization techniques has been evolving, shifting from the traditional optimization of radio parameters to the improvement of the quality perceived by users, known as quality of experience (QoE). In mobile networks, the radio link control (RLC) layer provides a reliable link between both ends of the communication and has a great impact on the QoE. In this paper, the optimization of the QoE for users based on the adjustment of the RLC layer is proposed. For this purpose, two typical services demanded by the users of mobile networks have been selected: the real-time video streaming service and file transfer service. For a broader view of the behavior of the QoE in relation to RLC, optimization tests have been carried out in scenarios with different system bandwidths. In this way, the relationship between the QoE and the optimal configuration of RLC in different network load situations has been analyzed. A proof of concept has been carried out to show the capability of this optimization. To that end, both a cellular network simulator and a live cellular network devised for research purposes have been used. Full article

(This article belongs to the Section Sensor Networks)

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21 pages, 3007 KiB

Open AccessArticle

PHY, MAC, and RLC Layer Based Estimation of Optimal Cyclic Prefix Length

by Adriana Lipovac, Vlatko Lipovac and Borivoj Modlic

Sensors 2021, 21(14), 4796; https://doi.org/10.3390/s21144796 - 14 Jul 2021

Cited by 12 | Viewed by 4276

Abstract

This work is motivated by growing evidence that the standard Cyclic Prefix (CP) length, adopted in the Long Term Evolution (LTE) physical layer (PHY) specifications, is oversized in propagation environments ranging from indoor to typical urban. Although this ostensibly seems to be addressed by 5G New Radio (NR) numerology, its scalable CP length reduction is proportionally tracked by the OFDM symbol length, which preserves the relative CP overhead of LTE. Furthermore, some simple means to optimize fixed or introduce adaptive CP length arose from either simulations or models taking into account only the bit-oriented PHY transmission performance. On the contrary, in the novel crosslayer analytical model proposed here, the closed-form expression for the optimal CP length is derived such as to minimize the effective average codeblock length, by also considering the error recovery retransmissions through the layers above PHY—the Medium Access Control (MAC) and the Radio Link Control (RLC), in particular. It turns out that, for given protective coding, the optimal CP length is determined by the appropriate rms delay spread of the channel power delay profile part remaining outside the CP span. The optimal CP length values are found to be significantly lower than the corresponding industry-standard ones, which unveils the potential for improving the net throughput. Full article

(This article belongs to the Special Issue Mobile Communications in 5G Networks)

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13 pages, 566 KiB

Open AccessArticle

On the Capability of QoE Improvement Based on the Adjustment of RLC Parameters

by Jessica Mendoza, Isabel de-la-Bandera, David Palacios, Ana Herrera-García and Raquel Barco

Sensors 2020, 20(9), 2474; https://doi.org/10.3390/s20092474 - 27 Apr 2020

Cited by 4 | Viewed by 2863

Abstract

The constant evolution in mobile communications networks have led operators to seek new techniques to optimize their mobile networks with the objective of satisfying the expectations of the users. In this way, traditional optimization techniques based on improving radio indicators, have given way to new techniques based on improving the quality of experience (QoE) perceived by users. This paper is focused on analyzing the impact of the adjustment of radio link control (RLC) layer configuration parameters on the QoE perceived by the users of two different types of services. Firstly, an evaluation of the QoE experienced by the user of a real-time video streaming service with respect to the transmission buffer size of the RLC layer in unacknowledged mode (UM) has been carried out. Secondly, the QoE perceived by the user of a file transfer service in relation to the variation of the configuration parameters of the RLC layer in acknowledged mode (AM) has been evaluated. The study, which has been carried out in a simulated cellular environment, has been performed for different system bandwidth values, thus proving the relationship between the QoE perceived by the users, the optimal RLC configuration parameters values and the available bandwidth. Full article

(This article belongs to the Section Communications)

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17 pages, 958 KiB

Open AccessArticle

Effect of AQM-Based RLC Buffer Management on the eNB Scheduling Algorithm in LTE Network

by Anup Kumar Paul, Hidehiko Kawakami, Atsuo Tachibana and Teruyuki Hasegawa

Technologies 2017, 5(3), 59; https://doi.org/10.3390/technologies5030059 - 14 Sep 2017

Cited by 13 | Viewed by 8518

Abstract

With the advancement of the Long-Term Evolution (LTE) network and smart-phones, most of today’s internet content is delivered via cellular links. Due to the nature of wireless signal propagation, the capacity of the last hop link can vary within a short period of time. Unfortunately, Transmission Control Protocol (TCP) does not perform well in such scenarios, potentially leading to poor Quality of Service (QoS) (e.g., end-to-end throughput and delay) for the end user. In this work, we have studied the effect of Active Queue Management (AQM) based congestion control and intra LTE handover on the performance of different Medium Access Control (MAC) schedulers with TCP traffic by ns3 simulation. A proper AQM design in the Radio Link Control (RLC) buffer of eNB in the LTE network leads to the avoidance of forced drops and link under-utilization along with robustness to a variety of network traffic-loads. We first demonstrate that the original Random Early Detection (RED) linear dropping function cannot cope well with different traffic-load scenarios. Then, we establish a heuristic approach in which different non-linear functions are proposed with one parameter free to define. In our simulations, we demonstrate that the performance of different schedulers can be enhanced via proper dropping function. Full article

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