Abstract-Upon the occurrence of a phenomenon of interest in a wireless sensor network, multiple sensors may be activated, leading to data implosion and redundancy. Data aggregation and/or fusion techniques exploit spatio-temporal correlation among sensory data to reduce traffic load and mitigate congestion. However, this is often at the expense of loss in Information Quality (IQ) of data that is collected at the fusion center.In this work, we address the problem of finding the leastcost routing tree that satisfies a given IQ constraint. We note that the optimal least-cost routing solution is a variation of the classical NP-hard Steiner tree problem in graphs, which incurs high overheads as it requires knowledge of the entire network topology and individual IQ contributions of each activated sensor node. We tackle these issues by proposing: (i) a topology-aware histogram-based aggregation structure that encapsulates the cost of including the IQ contribution of each activated node in a compact and efficient way; and (ii) a greedy heuristic to approximate and prune a least-cost aggregation routing path. We show that the performance of our IQ-aware routing protocol is: (i) bounded by a distance-based aggregation tree that collects data from all the activated nodes; and (ii) comparable to another IQ-aware routing protocol that uses an exhaustive brute-force search to approximate and prune the least-cost aggregation tree.
Abstract-Aloha has been proposed as the de facto MAC protocol in the IEEE 802.15.4a UWB-PHY standard for Low Rate WPANs (LR-WPANs). Unlike conventional wireless narrowband systems, the UWB-PHY provides Time-Hopping (TH) to enable multiple users to transmit simultaneously, thereby potentially increasing the overall system throughput. The intrinsic properties of the impulse-based UWB renders most existing narrowband MAC protocols which make use of carrier sensing unsuitable for use in UWB systems. In this paper, we study the throughput performance of slotted-Aloha, an enhanced version of the Aloha MAC protocol, over the TH-UWB physical layer, using both theoretical analysis and simulations. Our results show that slotted-Aloha over TH-UWB is able to provide good throughput performance when there exists an algorithm to optimally assign TH codes to the multiple users in the network.
Abstract-In this work, we study the time-slot allocation problem in a multi-sink single-hop TH-UWB network scenario, where the traffic from a sensor node is anycasted via a single hop to any one of multiple sinks. The slot allocation problem is formulated as an optimization problem and shown to be NP-hard. We then present a heuristic to increase network throughput and fairness as compared to a random allocation. In the proposed heuristic, nodes that are of similar distances to any sinks are grouped together to utilize the same set of TH slots for transmissions. Simulations show that the proposed heuristic improves both throughput and fairness, scales with multiple sinks and can be used as a simple admission control mechanism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.