B-MAC

Abstract: Applications designed for event driven monitoring represent a challenging class of applications for wireless sensor networks. They are a special kind of monitoring applications, since they usually need low data rates, but also require mechanisms for low latency and asynchronous communication. In this paper we will focus on optimizations at the MAC layer that enable low energy consumption when contention-based protocols are adopted. We present B-MAC+, an enhanced version of a widely adopted MAC protocol, and we show that substantial improvements, in terms of network lifetime, can be reached over the original protocol.

Abstract: The algorithms in this paper exploit optimal input structure in interference networks and is a major advance from the state-of-the-art. Optimization under multiple linear constraints is important for interference networks with individual power constraints, per-antenna power constraints, and/or interference constraints as in cognitive radios. While for single-user MIMO channel transmitter optimization, no one uses general purpose optimization algorithms such as steepest ascent because water-filling is optimal and much simpler, this is not true for MIMO multiaccess channels (MAC), broadcast channels (BC), and the non-convex optimization of interference networks because the traditional water-filling is far from optimal for networks. We recently found the right form of water-filling, polite water-filling, for some capacity/achievable regions of the general MIMO interference networks, named B-MAC networks, which include BC, MAC, interference channels, X networks, and most practical wireless networks as special cases. In this paper, we use weighted sum-rate maximization under multiple linear constraints in interference tree networks, a natural extension of MAC and BC, as an example to show how to design highly efficiency and low complexity algorithms. Several times faster convergence speed and orders of magnitude higher accuracy than the state-of-the-art are demonstrated by numerical examples.

Abstract: WSNs usually combine periodic readings with messages generated by unexpected events When an event is detected by a group of sensors, several notification messages are sent simultaneously to the sink, resulting in sporadic increases of the network load Additionally, these messages sometimes require a lower latency and higher reliability as they can be associated to emergency situations Current MAC protocols for WSNs are not able to react rapidly to these sporadic changes on the traffic load, mainly due to the duty cycle operation, adopted to save energy in the sensor nodes, resulting in message losses or high delays that compromise the event detection at sink In this work, two main contributions are provided: first, the collective QoS definitions are applied to measure event detection capabilities and second, a novel traffic-aware Low Power Listening MAC to improve the network response to sporadic changes in the traffic load is presented Results show that the collective QoS in terms of collective throughput, latency and reliability are improved maintaining a low energy consumption at each individual sensor node

Abstract: LWT-MAC is a new Low Power Listening MAC protocol for WSNs designed to rapidly react to instantaneous increases of the network load. It takes advantage of overhearing by waking up all nodes at the end of a transmission to send or receive packets without needing to transmit the long preamble before. In this work, detailed analytical models of the LWT-MAC and B-MAC protocols, for both saturated and unsaturated conditions, are presented. Moreover, the key LWT-MAC parameters are optimized in order to minimize the energy consumption, constrained to obtain the same throughput as the IEEE 802.11 (CSMA/CA) MAC protocol. From the behavior of the optimal LWT-MAC parameters, a heuristic configuration is proposed. Finally, the LWT-MAC is compared to B-MAC, in both single and multi-hop scenarios, showing improvements in energy consumption, throughput and delay.