Asset tracking is a critical problem in modern data centers with modular and easily movable servers. This paper studies a wireless asset tracking solution built using wireless USB (WUSB) radios that are expected to ubiquitous in future servers. This paper builds on our previous work on direct ranging using WUSB radios and studies algorithms for data center wide localization of all rack mounted servers. The results show that it is possible achieve very low error rates in localization in spite of very stringent constraints (i.e., each server being just 1.8" high) by exploiting the properties of the data center environment.

Abstract-This paper presents a detailed measurement based characterization of the Ultra Wideband (UWB) channels in a data center environment and examines the accuracy of direct ranging using Time of Arrival (ToA)measurements. Modern data centers present a unique indoor environment that to our knowledge has not yet been characterized. Our ranging experiments indicate that it is possible to achieve an accuracy of fraction of a meter via direct ranging and point to the feasibility of locating individual servers using more sophisticated cooperative ranging. Fig. 1. A row of racks in a data center

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A recent algorithm of Modiano selects packet In this paper we modify the algorithm of Modiano so that the sizes in a selective repeat ARQ protocol based on the proposed scheme adapts between one of only two preacknowledgement history of the most recently transmitted specified packet sizes. Our analysis follows closely the packets. In this paper we modify this algorithm so that analysis of [5], but in the process we also provide a simplified the choice of packet size is restricted to one of two presolution to equation (8) in [5]. The rest of the paper is

In this paper, we present a measurement based characterization of the Ultra Wideband (UWB) channel in a data center environment. We find that although a modified Saleh-Valenzuela model characterizes the UWB channel, some of the model parameters such as delay spread and log normal shadowing are unique to the data center environment.