Begonya Otal

Novel QoS scheduling and energy-saving MAC protocol for body sensor networks optimization

Wireless body sensor networks operate under the conflicting requirements of maintaining the desired reliability and message latency of data transmissions, while simultaneously maximizing battery-life of individual body sensors. In doing so, the characteristics of the operating environment, including physical, MAC and application layers have to be considered. The aim of this paper is the study of a novel quality-of-service fuzzy-rule based cross-layer scheduling algorithm under certain selected medical scenarios for body sensor networks optimization. To fulfill the above-mentioned requirements, not only are data packet transmissions scheduled taking the channel quality state among sensors into account, but also their packet waiting time in the accessing system and the specific body sensor applicability. Hereby we utilize an adapted distributed queuing MAC protocol that has recently been proved to be far more energy-efficient than the IEEE 802.15.4 standard for wireless sensor networks.

Design and analysis of an energy-saving distributed MAC mechanism for wireless body sensor networks

The fact that the IEEE 802.15.4 MAC does not fully satisfy the strict wireless body sensor network (BSN) requirements in healthcare systems highlights the need for the design and analysis of new scalable MAC solutions, which guarantee low power consumption to all specific sorts of body sensors and traffic loads. While taking the challenging healthcare requirements into account, this paper aims for the study of energy consumption in BSN scenarios. For that purpose, the IEEE 802.15.4 MAC limitations are first examined, and other potential MAC layer alternatives are further explored. Our intent is to introduce energy-aware radio activation polices into a high-performance distributed queuing medium access control (DQ-MAC) protocol and evaluate its energy-saving achievements, as a function of the network load and the packet length. To do so, a fundamental energy-efficiency theoretical analysis for DQ-MAC protocols is hereby for the first time provided. By means of computer simulations, its performance is validated using IEEE 802.15.4 MAC system parameters.

Power saving efficiency of a novel packet aggregation scheme for high-throughput WLAN stations at different data rates

Multiple MCS and receiver aggregation (MMRA) is a method to aggregate several MAC protocol data units (MPDUs) that are intended for different receivers and can be transmitted at different modulation and coding schemes (MCS) in the next generation of WLAN, the IEEE 802.11n protocol. Traditional aggregation schemes only link MPDUs between the same source and destination device pair together. The main purpose of aggregation is to reduce the number of access attempts to the medium and thereby significantly increase the protocol efficiency and data throughput. Analytical computations show that MMRA performs better not only in time efficiency compared to other single-rate aggregation schemes, where MPDUs aggregates belonging to different receivers are limited to the lowest MCS, but above all MMRA outperforms single-rate aggregation schemes in terms of power efficiency. MMRA provides a power saving frame format structure, which will allow receiving stations to reduce power consumption and save battery life, crucial for small handled devices.

Efficient Power Management Based on a Distributed Queuing MAC for Wireless Sensor Networks

Significant power is consumed at a sensor node when it either transmits a packet or when it receives a packet. In this paper, we study energy efficiency as a function of the number of sensors in the network and the payload length. Additionally, we propose power management solutions based on a distributed queuing MAC protocol for wireless sensor networks. Analytical values for the energy consumption performance are derived as a function of the system parameters. The obtained results show that our proposed MAC scheme outperforms that of IEEE 802.15.4. These benefits are obtained from eliminating back-off periods and collisions in data packet transmissions while minimizing the control overhead and the overall energy consumption

A cross-layer energy-saving mechanism for an enhancement of 802.11 WLAN systems

Most multiple access collision avoidance-based (MAC) protocols for WLAN systems have been using fixed transmission power and have not considered energy-saving techniques targeted on channel estimation models. In order to prolong battery life and to improve the overall throughput performance of such systems, a novel PHY-MAC cross-layer energy-saving mechanism based on a distributed queuing MAC protocol and fuzzy logic theory is introduced for WLAN systems. Computer simulations have been performed and values for the throughput maximum performance and energy consumption have been obtained as a function of different scenario parameters. These values show that the throughput outperforms the one obtained with the IEEE 802.11 standard while reducing the energy consumption.

A New MAC Approach in Wireless Body Sensor Networks for Health Care

Although the challenges faced by wireless body sensor networks (BSNs) in healthcare environments are in a certain way similar to those already existing in current wireless sensor networks (WSNs), there are intrinsic differences, which require special attention (Yang, 2006). For instance, human body monitoring may be achieved by attaching sensors to the body’s surface as well as implanting them into tissues for a more accurate clinical practice. One of the major concerns is thereby that of extremely energy efficiency, which is the key to extend the lifetime of battery-powered body sensors, reduce maintenance costs and avoid invasive procedures to replace battery in the case of implantable devices. That is, BSNs in healthcare systems operate under conflicting requirements. These are the maintenance of the desired reliability and message latency of data transmissions, while simultaneously maximizing battery lifetime of individual body sensors. In doing so, the characteristics of the entire system, including physical (PHY), MAC and application (APP) layers have to be considered. In fact, the MAC layer is the one responsible for coordinating channel accesses, by avoiding collisions and scheduling data transmissions, to maximize throughput efficiency (and reliability) at an acceptable packet delay and minimal energy consumption. Now, the design of future MAC protocols for BSNs must tackle stringent quality of service (QoS) requirements, apart from the desired low power consumption. Hence, the right MAC approach is able to handle cross-layer PHY-MAC-APP features. In order to consider all the aforementioned healthcare requirements, this chapter first concentrates on the analysis and evaluation of the energy consumption in a MAC level. Thereafter, novel cross-layer fuzzy-logic techniques are proposed to enhance QoS resource management in the here portrayed MAC approach for BSNs. Simulation results are achieved to validate the overall system performance, and its scalability, by increasing the number of wireless on-body sensors in the BSN (see Fig. 1). In this context, among all IEEE 802 standards available today, the IEEE 802.15.4 (802.15.4, 2003) is regarded as the technology of choice for most BSN research studies (Yang, 2006); (Zhen et al., 2007); (Kumar et al., 2008). However, the 802.15.4 MAC is not actually intended to support any set of applications with stringent QoS, and, even though it consumes very low power, the figures do not reach the levels required in BSNs (Zhen et al., 2007); (Kumar 6

Optimizing MAC Layer Performance Based on a Distributed Queuing Protocol for Wireless Sensor Networks

This paper analyzes the performance of a MAC scheme for low-rate wireless sensor networks that makes use of distributed queues to improve radio channel utilization. Analytical values first for the throughput performance, and later for the energy consumption are derived as a function of the system parameters. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in terms of maximum stable throughput and overall performance, including energy consumption. These benefits are obtained from eliminating backoff periods and collisions in data packet transmissions while minimizing the control overhead. Our proposal takes advantage of being independent of the number of transmitting sensors in the system providing stability for all traffic scenarios and showing that a reduction of energy consumption compared to IEEE 802.15.4 MAC is still possible.