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Routing Protocols for Wireless Sensor Networks that have an Opportunistic Large Array (OLA) Physical Layer
Lakshmi V. Thanayankizil, Aravind Kailas and Mary Ann Ingram

The Opportunistic Large Array (OLA) is a simple strategy that provides a Signal-to-Noise Ratio (SNR) advantage from the spatial diversity of distributed single-antenna radios. In this paper, we present a collection of broadcasting and upstream routing protocols that have been developed for the OLA physical layer. We consider several benefits of OLA transmissions, namely, energy efficiency, survivability during network partitions, improved latency, and robustness against mobility. The strategies for broadcast are OLA with Transmission Threshold (OLA-T) and Alternating OLA-T (A-OLA-T), and the main upstream routing scheme is the OLA Concentric Routing Algorithm (OLACRA). These schemes exploit the nature of OLA broadcasts and limit the number of nodes participating in each hop to reduce the aggregate transmit energy consumed in the network. To increase the network survivability during partition, we propose a new survivable network protocol that detects a network partition and triggers the creation of a large enough OLA to overcome the partition. All of the OLA-based routing schemes share the properties of no centralized control, no individual node addressing, no inter-node coordination, no reliance on node location knowledge, and no dependence on density, given that the density is at least sufficient to support OLA transmission. These properties imply that the OLA-based protocols are scalable with node density and robust against mobility.

Keywords: Broadcasting, cooperative transmission, energy-efficiency, mobility, network life extension, disconnected networks, opportunistic large arrays, survivability, wireless sensor networks.

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