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Abstract-Every surgical item used during surgery (e.g., sponges) must be accounted for after surgery to ensure that none of these items is left inside the patient. Despite the numerous precautions in place, in approximately 1 in 1500 cases, something gets left behind inside the patient's body. This paper presents ASSIST, an automated system for surgical instrument and sponge tracking that increases the safety of surgical procedures. ASSIST utilizes RFID (Radio Frequency Identification) technology to aid in accounting for all items used during surgery. The design takes into account safety, simplicity, ease of deployment, and ease of use. An initial evaluation utilizing RFID-tagged sponges demonstrates that ASSIST can reliably track surgical sponges with minimal impact to current operating room procedures. Sources of error that can impact the reliability of the system are also discussed.

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Abstract-Low-cost wireless routers are changing the way people connect to the Internet. They are also very cheap, albeit quite limited, Linux boxes. These attributes make them ideal candidates for wireless mesh routers. This paper presents a minimally invasive mechanism for redundant multipath routing in kernel-space to achieve high reliability with high throughput in a mesh network. This service is essential for achieving fast, lossless handoff as mobile devices roam throughout the wireless mesh coverage area. However, redundant multipath is not natively supported by current operating systems, limiting the routing mechanisms that can be used in these networks to user-level implementations, which can greatly degrade performance.We show an architecture that integrates this mechanism in a wireless mesh system, resulting in a high-throughput 802.11 mesh network with fast handoff over low-cost routers.

Wireless mesh networks extend the connectivity range of mobile devices by using multiple access points, some of them connected to the Internet, to create a mesh topology and forward packets over multiple wireless hops. However, the quality of service provided by the mesh is impaired by the delays and disconnections caused by handoffs, as clients move within the area covered by multiple access points. We present the architecture and protocols of SMesh, the first transparent wireless mesh system that offers seamless, fast handoff, supporting real-time applications such as interactive VoIP. The handoff and routing logic is done solely by the access points, and therefore connectivity is attainable by any 802.11 device. In SMesh, the entire mesh network is seen by the mobile clients as a single, omnipresent access point, giving the mobile clients the illusion that they are stationary. We use multicast for access points coordination and, during handoff transitions, we use more than one access point to handle the moving client. SMesh provides a hybrid routing protocol that optimizes routes over wireless and wired links in a multi-homed environment. Experimental results on a fully deployed mesh network demonstrate the effectiveness of the SMesh architecture and its intra-domain and inter-domain handoff protocols.

Abstract-Push-to-Talk (PTT) is a useful capability for rapidly deployable wireless mesh networks used by first responders. PTT allows several users to speak with each other while using a single, half-duplex, communication channel, such that only one user speaks at a time while all other users listen.This paper presents the architecture and protocol of a robust distributed PTT service for wireless mesh networks. The architecture supports any 802.11 client with SIP-based (Session Initiation Protocol) VoIP software and enables the participation of regular phones. Collectively, the mesh nodes provide the illusion of a single third party call controller, enabling clients to participate via any reachable mesh node. Each PTT group instantiates its own logical floor control manager that is highly available and resilient to mesh connectivity changes such as node crashes and recoveries and network partitions and merges. Experimental results on a fully deployed mesh network consisting of 14 mesh nodes and tens of emulated clients demonstrate the scalability and robustness of the system.