Search results for "Computer network"
showing 10 items of 1634 documents
A Lite Romanian BERT: ALR-BERT
2022
Large-scale pre-trained language representation and its promising performance in various downstream applications have become an area of interest in the field of natural language processing (NLP). There has been huge interest in further increasing the model’s size in order to outperform the best previously obtained performances. However, at some point, increasing the model’s parameters may lead to reaching its saturation point due to the limited capacity of GPU/TPU. In addition to this, such models are mostly available in English or a shared multilingual structure. Hence, in this paper, we propose a lite BERT trained on a large corpus solely in the Romanian language, which we cal…
The diffusion and use of information and communication technologies and the city from 1996 to 2009
2013
The aim of this paper is to investigate whether the diffusion and the use of information and communication technologies (ICTs) are associated with the size of the place of residence where people live. The article explores how the relationship between ICTs and place of residence changed between 1996 and 2009. The study presents data from two consecutive telephone surveys collected from Italy, France, Germany, the United Kingdom and Spain. Results show an unexpected role of the relatively rural areas as attractor of new technologies. Although the largest cities have remained the locus of telecommunications on the whole, the relationship between ICTs and the place of abode has changed consider…
Development of a Simulator for Prototyping Reinforcement Learning-Based Autonomous Cars
2022
Autonomous driving is a research field that has received attention in recent years, with increasing applications of reinforcement learning (RL) algorithms. It is impractical to train an autonomous vehicle thoroughly in the physical space, i.e., the so-called ’real world’; therefore, simulators are used in almost all training of autonomous driving algorithms. There are numerous autonomous driving simulators, very few of which are specifically targeted at RL. RL-based cars are challenging due to the variety of reward functions available. There is a lack of simulators addressing many central RL research tasks within autonomous driving, such as scene understanding, localization and mapping, pla…
Scheduling solution for the IEEE 802.16 base station
2008
The IEEE 802.16 standard defines a wireless broadband access network technology called WiMAX. It introduces several advantages, one of which is the support for QoS at the MAC level. To ensure meeting the QoS requirements, the 802.16 base station must run some algorithm to allocate slots between connections. This algorithm is not defined in the 802.16 specification but rather is open for alternative implementations. We propose a simple, yet efficient, solution that is capable of allocating slots based on the QoS requirements, bandwidth request sizes, and the 802.16 network parameters. To test the proposed solution, we have implemented the 802.16 MAC and PHY layers in the NS-2 simulator. Seve…
Handover performance in the IEEE 802.16 mobile networks
2012
The IEEE 802.16 standard provides a full mobility support for stations moving across cell borders. In addition, the WiMAX Forum Network Working Group defines a set of procedures to support handovers in the mobile access network. One of the main characteristics of mobility support is fully controlled and optimized handover (HO), in which a mobile station (MS) migrates from the air interface of one base station (BS) to another one. It is vital to keep the BS transition phase as short as possible to decrease delays and data loss, which is especially crucial for real-time applications, such as VoIP. In this paper we analyze ASN-anchored mobility performance and provide advisable handover relate…
Optimal MAC PDU Size in IEEE 802.16
2008
In the IEEE 802.16 the number of errors and the MAC PDU size have an impact on the performance of the network. We present a way to estimate the optimal PDU size and we run a number of simulation scenarios to study these parameters and how they impact on the performance of application protocols. The simulation results reveal that the channel bit error rate has a major impact on the optimal PDU size in the IEEE 802.16 networks. Also, the ARQ block rearrangement influences the performance.
Performance Evaluation of the IEEE 802.16 ARQ Mechanism
2007
The IEEE 802.16 technology defines the ARQ mechanism that enables a connection to resend data at the MAC level if an error is detected. In this paper, we analyze the key features and parameters of the ARQ mechanism. In particular, we consider a choice for the ARQ feedback type, a scheduling of the ARQ feedbacks and retransmissions, the ARQ block rearrangement, ARQ transmission window and ARQ block size. We run a number of simulation scenarios to study these parameters and how they impact a performance of application protocols. The simulation results reveal that the ARQ mechanism plays an important role in transmitting data over wireless channels in the IEEE 802.16 networks.
Performance comparison of HARQ and ARQ mechanisms in IEEE 802.16 networks
2008
The IEEE 802.16 technology defines several link level mechanisms to retransmit erroneous data. In this paper we compare the performance of the ARQ and HARQ mechanisms in the IEEE 802.16 networks. Our simulations results show that in general HARQ provides a better performance. However, ARQ can compete successfully with it due to a smaller signaling overhead. Furthermore, since ARQ does not require a dedicated uplink signaling channel for the acknowledgments messages, it results in better resources utilization in the uplink direction.
Analysis of the IEEE 802.11e EDCA Under Statistical Traffic
2006
Many models have been proposed to analyze the performance of the IEEE 802.11 distributed coordination function (DCF) and the IEEE 802.11e enhanced distributed coordination function (EDCA) under saturation condition. To analyze DCF under statistical traffic, Foh and Zukerman introduce a model that uses Markovian Framework to compute the throughput and delay performance. In this paper, we analyze the protocol service time of EDCA mechanism and introduce a model to analyze EDCA under statistical traffic using Markovian Framework. Using this model, we analyze the throughput and delay performance of EDCA mechanism under statistical traffic.
Link Adaptation Thresholds for the IEEE 802.16 Base Station
2008
The IEEE 802.16 technology defines a number of modulation and coding schemes that the base station can use to achieve the best tradeoff between the spectrum efficiency and the resulting application level throughput. However, the 802.16 specification does not define any particular link level adaptation algorithm, neither does it specify the SNR thresholds to switch between modulation and coding schemes. In this paper we consider a link adaptation model and conduct a number of simulation runs to find transition thresholds for ARQ and HARQ retransmission mechanisms. All the simulations are done with the 802.16 extension for the NS-2 simulator.