Lih-Feng Tsaur

An on-demand scatternet formation and multi-hop routing protocol for BLE-based wireless sensor networks

As new features are introduced into the Bluetooth core specification, the ability to use Bluetooth Low Energy (BLE) technology to construct a mobile ad-hoc network (MANET) becomes a reality. Key features included in Bluetooth Specification version 4.1 are the ability for a single node to be part of multiple piconets, and the ability for a node to act dual mode, as both a piconet master and slave. These features allow the possibility of multi-hop routing spanning multiple connected piconets. Although multi-hop routing is theoretically possible with version 4.1, no multi-hop routing algorithm has never been presented which exploits this possibility. In this paper we propose an approach to scatternet formation and multi-hop routing for networks using BLE version 4.1. We define procedures for device discovery, communication between piconets and forming multi-hop scatternet. Our approach has the following properties, 1) it can be used with existing Bluetooth hardware, 2) the protocol is fully distributed, so global connectivity information is not required for formation and routing, and 3) it supports ad-hoc network formation. We have implemented our approach using real Bluetooth SoCs including the Broadcom BCM434x chipset which is used in the iPhone 6. Our experiments demonstrate the routing delay and throughput using networks containing different numbers of nodes in order to demonstrate the impact of network size on performance. As the network size increases, our protocol does not incur a large delay and achieves better resource utilization.

An efficient approach to prevent Battery Exhaustion Attack on BLE-based mesh networks

As the need for mesh networks for Internet of Things (IoT) applications grows, research in this field attracts more and more attention. Because IoT devices are primarily battery-driven, Bluetooth Low Energy (BLE) networking is appealing to conserve battery life. The importance of battery life in a mobile ad hoc network increases the sensitivity of the network to cyber-attacks intended to impact battery life. A Battery Exhaustion Attack can overwhelmingly exhaust the batteries of network nodes by making malicious service requests. In this paper, we present an intrusion detection and prevention approach for this type of attack. This approach requires the suspicious nodes to switch connection to the neighbors of its connected nodes periodically. When a suspicious node is identified as malicious, it is blacklisted to prevent future attacks. Even when a malicious node cannot be detected, its impact is distributed across the network in order to extend the overall network lifetime.

A residual battery-aware routing algorithm based on DSR for BLE sensor networks

The newest version of the Bluetooth core specification, version 4.2, includes Bluetooth Low Energy (BLE) technology and is enabling an explosion of new mobile, wearable, home, and industrial devices which can communicate with each other. Part of the burgeoning Internet of Things (IoT), these devices require low power methods for forming mobile ad-hoc networks (MANETs). In this work we present BLE Scatternet Battery-Aware Routing (BSBR), a power aware routing mechanism based on Dynamic Source Routing (DSR) which can be applied to BLE-based MANETs. Experiments utilizing actual BLE hardware implementing the new specification show that BSBR increases network lifetime by over 15% while increasing throughput performance by up to 50% compared to a traditional BLE-based MANET routing algorithm. By taking advantage of BLE features to produce high performance, energy efficient ad-hoc networks BSBR can potentially enable new applications and devices for the Internet of Things.

Fighting against access collision and hidden node problem in broadcast scheme of wireless ad hoc networks

Broadcast service is an integral part of wireless networks, through which important control and signaling information are typically exchanged. However, its multi-receiver nature determines that broadcast suffers more from access collision and hidden node problem. In wireless ad hoc networks, the phenomenon becomes even worse due to the absence of a central coordinator. Existing media access control (MAC) protocols in wireless ad hoc networks were primarily designed for unicast service and the potential broadcast support is not satisfying. In this paper, we introduce a MAC layer protocol, namely Parallel Signaling and Persistently Synchronous MAC (PS2MAC) that can significantly alleviate both access collision and hidden node problem. A novel relay technique is deployed in PS2MAC so that a superior broadcast performance, such as throughput and packet delivery ratio, is achieved. The conclusion is supported with simulation analysis.