An analytical model of inter-channel interference in Bluetooth-based systems

One of the main advantages of the Bluetooth standard is that it provides a way to support ad-hoc connectivity between a variable number of devices at low cost. However, in situations with many Bluetooth devices that coexist in the same area the problem of channel interference may become of high importance. In this paper, we present an analysis that provides some expressions for the channel throughput and the delay that packets suffer due to possible collisions with other Bluetooth devices. The model includes the different effects of new and retransmitted packets. Both synchronized and unsynchronized systems are considered. Furthermore, although the effect of propagation losses are not explicitly considered, we show how they could be included in our model.Ministerio de Ciencia y Tecnología TIC2001-1868-C03-02Ministerio de Ciencia y Tecnología TIC2000-0087-P4-0

Performance analysis of single-slave Bluetooth piconets under cochannel interference

We present an analytical model for single-slave Bluetooth piconets when the coexistence of multiple interfering devices produces collisions. Closed-form expressions for the channel throughput and the mean packet delay are obtained, including the time spent waiting on the node's queue. The effect of propagation losses and asynchronous piconets are also discussed. The results of the analysis are validated through simulation.Ministerio de Ciencia y Tecnología TIC2001-1868-C03-02Ministerio de Ciencia y Tecnología TIC2000-0087-P4-0

Co-existence of wireless communication systems in ISM bands: An analytical study

Ph.DDOCTOR OF PHILOSOPH

A MODEL OF PACKET LOSS CAUSED BY INTERFERENCE BETWEEN THE BLUETOOTH LOW ENERGY COMPONENT OF AN IOS WEARABLE BODY AREA NETWORK AND RESIDENTIAL MICROWAVE OVENS

Cardiovascular diseases are the leading cause of death in the United States. Advances in wireless technology have made possible the remote monitoring of a patient’s heart sensors as part of a body area network. Previous studies have suggested that stray wireless transmissions in the industrial, scientific, and medical (ISM) band cause interference resulting in packet loss in Bluetooth piconets. This study investigates the impact that wireless transmissions from residential microwave ovens have on the Bluetooth Low Energy (BLE) component of the body area network. Using a systematic data collection approach, two variables were manipulated. The distance between the microwave oven and the BLE piconet was varied from 0.5 meter to 5.0 meters at one-half meter increments. At each distance, the power level of the microwave oven was varied from the lowest power setting to the highest power setting. The two variables that were collected were the microwave interference generated by channel and the packet loss by channel. The results suggest more packet loss is due to the microwave oven’s power level than by the distance, the interference caused by the microwave oven affects all BLE channels equally, and the packet loss by channel is a good predictor of microwave oven interference. The significance of this study lies in providing beneficial information to the medical and digital communication industries concerning the causes and solutions to disruptions in the Bluetooth-enabled body area network devices in a very common situation. The results of this study may lend support for improvements and widespread use of body area network medical systems, which may have the benefit of better monitoring, more data, and reduced fatalities due to misdiagnosed heart conditions

Energy efficient medium access control for wireless sensor networks

A wireless sensor network designates a system composed of numerous sensor nodes distributed over an area in order to collect information. The sensor nodes communicate wirelessly with each other in order to self-organize into a multi-hop network, collaborate in the sensing activity and forward the acquired information towards one or more users of the information. Applications of sensor networks are numerous, ranging from environmental monitoring, home and building automation to industrial control. Since sensor nodes are expected to be deployed in large numbers, they must be inexpensive. Communication between sensor nodes should be wireless in order to minimize the deployment cost. The lifetime of sensor nodes must be long for minimal maintenance cost. The most important consequence of the low cost and long lifetime requirements is the need for low power consumption. With today's technology, wireless communication hardware consumes so much power that it is not acceptable to keep the wireless communication interface constantly in operation. As a result, it is required to use a communication protocol with which sensor nodes are able to communicate keeping the communication interface turned-off most of the time. The subject of this dissertation is the design of medium access control protocols permitting to reach a very low power consumption when communicating at a low average throughput in multi-hop wireless sensor networks. In a first part, the performance of a scheduled protocol (time division multiple access, TDMA) is compared to the one of a contention protocol (non-persistent carrier sensing multiple access with preamble sampling, NP-CSMA-PS). The preamble sampling technique is a scheme that avoids constant listening to an idle medium. This thesis presents a low power contention protocol obtained through the combination of preamble sampling with non-persistent carrier sensing multiple access. The analysis of the strengths and weaknesses of TDMA and NP-CSMA-PS led us to propose a solution that exploits TDMA for the transport of frequent periodic data traffic and NP-CSMA-PS for the transport of sporadic signalling traffic required to setup the TDMA schedule. The second part of this thesis describes the WiseMAC protocol. This protocol is a further enhancement of CSMA with preamble sampling that proved to provide both a low power consumption in low traffic conditions and a high energy efficiency in high traffic conditions. It is shown that this protocol can provide either a power consumption or a latency several times lower that what is provided by previously proposed protocols. The WiseMAC protocol was initially designed for multi-hop wireless sensor networks. A comparison with power saving protocols designed specifically for the downlink of infrastructure wireless networks shows that it is also of interest in such cases. An implementation of the WiseMAC protocol has permitted to validate experimentally the proposed concepts and the presented analysis