Keuchul Cho

Analysis of Latency Performance of Bluetooth Low Energy (BLE) Networks

Bluetooth Low Energy (BLE) is a short-range wireless communication technology aiming at low-cost and low-power communication. The performance evaluation of classical Bluetooth device discovery have been intensively studied using analytical modeling and simulative methods, but these techniques are not applicable to BLE, since BLE has a fundamental change in the design of the discovery mechanism, including the usage of three advertising channels. Recently, there several works have analyzed the topic of BLE device discovery, but these studies are still far from thorough. It is thus necessary to develop a new, accurate model for the BLE discovery process. In particular, the wide range settings of the parameters introduce lots of potential for BLE devices to customize their discovery performance. This motivates our study of modeling the BLE discovery process and performing intensive simulation. This paper is focused on building an analytical model to investigate the discovery probability, as well as the expected discovery latency, which are then validated via extensive experiments. Our analysis considers both continuous and discontinuous scanning modes. We analyze the sensitivity of these performance metrics to parameter settings to quantitatively examine to what extent parameters influence the performance metric of the discovery processes.

Performance analysis of device discovery of Bluetooth Low Energy (BLE) networks

Abstract Bluetooth Low Energy (BLE) technology has opened a whole new dimension of single-hop wireless communication technology due to its inexpensive and low-power properties. This technology makes it possible for a large number of devices to be connected to the Internet of Things. The BLE mechanism is clearly defined by the standard, however, there is room for improvements in some aspects of the technology such as the discovery process. Although the discovery process of traditional Bluetooth architecture has been intensively investigated through analytical and simulation models over the years, it cannot be applied to the BLE technology because of many changes introduced in the design of the BLE. Recently, there have been several works for performance evaluation of BLE discovery process, but they are not still thorough enough in providing a holistic analysis of the BLE. This has motivated our study for more accurate modeling of the BLE discovery process. Our work focuses on developing an analytical model and carrying out intensive simulations to investigate discovery probability and quantitative examination of the influence of parameter settings on the discovery latency and the energy performance metric of the discovery process.

AdaptiveScan: The Fast Layer-2 Handoff for WLAN

Recently, handoff is a critical issue for stations in IEEE 802.11-based wireless networks. In order to provide VoIP (Voice over IP) and real-time streaming applications for stations, handoff mechanism must be provided for reducing latency and seamless communication. However, the IEEE802.11 standards handoff is not appropriate to supply their QoS, because it is based on a full-scanning approach. Full-scanning spends too much time searching Access Point (AP). Therefore, the various pre-scan handoff protocols such as Sync Scan and Deuce Scan have been proposed. They perform scanning to find nearby APs before station is out of contact with AP, but they have much overhead for pre-scanning. Our handoff mechanism reduces the delay and overhead associated with link layer handoff by periodically scanning the channel groups. We prove that our per-scanning mechanism supports a faster handoff and has a lower overhead compared to the conventional schemes.

A discovery scheme based on carrier sensing in self-organizing Bluetooth Low Energy networks

Bluetooth Low Energy (BLE) gets lots of attention from researchers as one of the most prominent solutions for short range communications. But, the BLE still has many challenging issues which must be resolved before deploying it for the technologies. In this paper, an enhanced discovery mechanism is proposed for BLE devices to avoid collisions during advertisement process, so as to achieve lower latency as well as energy consumption. The proposed scheme is modeled and validated via analytical and simulation methods. The proposed mechanism has shown its effectiveness in avoiding unexpected long latency and much energy consumption by carrier sensing during discovery process in crowded BLE networks.

Path management scheme to support mobile station in wireless mesh networks for U-healthcare applications

In expanded service area of wireless mesh network to support mobility of the mobile station research is recognized as an important issue. Due to the mobile station move frequently to changing the path, data loss and network performance degradation are often occur, such as the service broken. In the existing research of support mobility, the Layer 3 or mobility is required, but it may cause the backup server overhead. This paper is based the 802.11s, the proposed scheme supports station mobility without any additional elements by using Layer 2.

A Self-Adjustable Rate Control in Wireless Body Area Networks

The convergent feature of traffic in wireless body area networks (WBANs) makes congestion in certain areas which are the place of events and/or the location of sensor nodes near a sink. Congestion brings packet loss, retransmission, and delay at the node and it also causes the consumption of additional energy. Therefore there is no doubt that congestion needs to be controlled efficiently. In this paper, we suggest a self-adjustable rate control in WBANs. Our scheme performs rate control dynamically each node based on a predication model which uses rate function including congestion risk degree and valuation function, without requiring congestion detection and congestion notification steps. We carry out the operation of our scheme and have demonstrated our rate control to be efficient. We also show that the negative effects from network congestion can be greatly mitigated as compared with a no rate control mechanism.

Modeling and analysis of performance based on Bluetooth Low Energy

Bluetooth Low Energy (BLE) is one of the optimal candidate technology used in short range wireless communications. The features of BLE such as low-cost and low-power dominates it over other technologies such ZigBee, etc. The BLE 4.0 standard provides the in-depth analysis of the BLE architecture. But still many aspects regarding the discovery process of the BLE needs refinement. The performance evaluation of the classical Bluetooth analysis is widely studied, but it cannot apply to the BLE 4.0 standard. Several schemes have been proposed in this regard, but none of them provides the complete discovery process analysis. Therefore, in this paper we provide a complete, new, and an accurate discovery process of BLE standard. The intensive analytical and simulation study provide a basis for the modeling of the BLE discovery process. Moreover, the proposed analysis investigates discovery probability as well as expected discovery latency in a wireless sensor network based on BLE, which are then validated via extensive experiments. We also investigate different parameters which directly affect the performance of the BLE discovery process. The parameters settings are examined, and an optimal setting is also proposed for low-power consumption during the discovery process.

An Adaptive Parameter Setting Algorithm to Enhance Performance in Self-Organizing Bluetooth Low Energy Networks

Bluetooth Low Energy (BLE) evolved from classical Bluetooth technologies for enabling short-range communication in different services and systems. BLE has many advantages over classical Bluetooth technologies, including low-cost deployment and low-power consumption. Recently, a very few number of research studies have been conducted to improve device discovery process of BLE. But, these studies have still some limitations. Prior studies have assumed that advertising PDUs are immediately processed as long as they are received successfully by a scanner. Practically, however, BLE devices may experience lots of collisions due to contention among neighbors, particularly in a crowded environment. With increasing number of BLE devices, delays of both device discovery and connection setup keep exponential growth, which could influence user experience in terms of either time or energy consumption. In this paper, an enhanced mechanism is proposed to enable BLE advertisers and scanners to learn the network contention and adjust their parameters accordingly, so as to achieve fast discovery latency. Through extensive simulations, the proposed mechanism has shown its effectiveness to reduce unexpected long latency in crowded BLE networks.

Traffic Classification Approach Based on Support Vector Machine and Statistic Signature

As network traffic is dramatically increasing, classification of application traffic becomes important for the effective use of network resources. Classification of network traffic using port-based or payload-based analysis is becoming increasingly difficult because of many peer-to-peer (P2P) applications using dynamic port numbers, masquerading techniques, and encryption. An alternative approach is to classify traffic by exploiting the distinctive characteristics of applications. In this paper, we propose a classification method of application traffic using statistic signatures based on SVM (Support Vector Machine). The statistic signatures, defined as a directional sequence of packet size in a flow, are collected for each application, and applications are classified by SVM mechanism.

An application dependent and sequential scanning scheme for vertical handover management in heterogeneous wireless networks

A mobile device with multiple interfaces consumes more energy for scanning of available networks during handover compared with one having a single interface. As the number of available networks increases, the discovery and selection of an optimal network consumes much energy for scanning, therefore, reduces battery life time. To cope with such problems, we propose an energy efficient scanning scheme for vertical handover management in heterogeneous networks. The proposed scheme employs a sequential scheduling strategy to avoid unnecessary scan, and controls scanning period depending on the type of application running on a Mobile Node (MN) to speed up discovery process. Performance evaluation shows that the proposed scheme uses less energy compared with the periodic and adaptive scanning procedures.