This paper investigates a fundamental networking problem in underwater sensor networks: robust and energy-efficient routing. We present an adaptive location-based routing protocol, called hop-by-hop vector-based forwarding (HH-VBF). It uses the notion of a "routing vector" (a vector from the source to the sink) acting as the axis of the "routing pipe", similar to the vector based forward (VBF) routing in the work of P. Xie, J.-H. Cui and L. Lao (VBF: Vector-Based Forwarding Protocol for Underwater Sensor Networks. Technical report, UCONN CSE Technical Report: UbiNet-TR05-03 (BECAT/CSE-TR-05-6), Feb. 2005). Unlike the original VBF approach, however, HH-VBF suggests the use of a routing vector for each individual forwarder in the network, instead of a single network-wide source-to-sink routing vector. By the creation of the hop-by-hop vectors, HH-VBF can overcome two major problems in VBF: (1) too small data delivery ratio for sparse networks; (2) too sensitive to "routing pipe" radius threshold. We conduct simulations to evaluate HH-VBF, and the results show that HH-VBF yields much better performance than VBF in sparse networks. In addition, HH-VBF is less sensitive to the routing pipe radius threshold. Furthermore, we also analyze the behavior of HH-VBF and show that assuming proper redundancy and feedback techniques, HH-VBF can facilitate the avoidance of any "void" areas in the network.

As an emerging technique, underwater sensor network (UWSN) will enable a wide range of aquatic applications. However, due to the adverse underwater environmental conditions as well as some system constraints, an underwater sensor network is usually viewed as an intermittently connected network (ICN) (or delay/disruption tolerant network (DTN)), which requires specialized routing protocols. Moreover, applications may have different requirements for different types of messages, as demands a smart protocol to handle packets adaptively. In this paper, we propose a novel routing protocol where routing is performed adaptively based on the types of messages and application requirements. This is obtained by exploiting message redundancy and resource reallocation in order to achieve different performance requirements. We demonstrate through simulations that our protocol can satisfy different application requirements and achieve a good trade-off among delivery ratio, end-to-end delay and energy consumption.

Serious games embody a class of applications able to produce real world benefits for individuals, or for the society, through the entertainment of players engaged in a game. The peculiarity of a fun participation and the vast variety of real benefits which can be generated have recently attracted an increasing number of researchers and practitioners toward this field. In this paper, we focus on the specific context of serious games related to healthcare and propose a mobile-based application for wrist rehabilitation. The proposed solution represents a prototype for a new generation of ubiquitous gametherapies.