Computer Science

Abstract In many robotics applications, knowing the material properties around a robot is often critical for the robot's successful performance. For example, in mobility, knowledge about the ground surface may determine the success of a robot's gait. In manipulation, the physical properties of an object may dictate the results of a grasping strategy. Thus, a reliable surface identification system would be invaluable for these applications.

ABSTRACT—New smartphone technologies are emerging which combine head-mounted displays (HMD) with standard functions such as receiving phone calls, emails, and helping with navigation. This opens new opportunities to explore cyber robotics algorithms (robotics sensors and human motor plant). To make these devices more adaptive to the environmental conditions, user behavior, and user preferences, it is important to allow the sensor-equipped devices to efficiently adapt and respond to user activities (e.g., disable incoming phone calls in an elevator, activate video recording while car driving). This paper hence presents a situation awareness system (SAS) for head-mounted smartphones. After collecting data from inertial sensors (accelerometers, gyroscopes), and video data (camera), SAS performs activity classification in three steps. Step 1 transforms inertial sensor data into a head orientation-independent and stable normalized coordinate system. Step 2 extracts critical features (sta...

Abstract Multiple transmission rates are supported in the current 802.11 WLANs, which allows stations to exploit different rates in an adaptive manner to cope with the variability of wireless channels and achieve the higher system throughput. Many efforts have been made at rate adaptation in the literature. The design of rate adaptation algorithms needs to take four basic issues into account.

Abstract Underwater communications is a very challenging topic due to its singular channel characteristics. Most protocols used in terrestrial wireless communications can not be directly applied in the underwater world. A high bit error rate and low propagation delay make the design of reliable transport protocols especially awkward. In this paper, we first propose four schemes that combine forward error correction mechanisms at the bit and/or packet level to increase the reliability in a non-cooperative scenario.

Abstract The mobility of underwater sensor nodes makes the network topology inconveniently controlled and slowly changed. Thus, in order to enable underwater sensor networks to work more effectively, it is necessary for us to periodically detect the coverage rate and redeploy nodes to non-coverage areas. In this paper, we take the lead in introducing the redeployment issue in underwater sensor networks. In our opinion, the key point of the redeployment issue is coverage.

Abstract The ubiquity of smartphones and their on-board sensing capabilities motivates crowd-sensing, a capability that harnesses the power of crowds to collect sensor data from a large number of mobile phone users. Unlike previous work on wireless sensing, crowd-sensing poses several novel requirements: support for humans-in-the-loop to trigger sensing actions or review results, the need for incentives, as well as privacy and security.

Abstract Underwater communication is a very challenging topic. Protocols used in terrestrial sensor networks cannot be directly applied in the underwater world. High-bit error rate and large propagation delay make the design of transport protocols especially awkward. ARQ-based reliable transport schemes are not appropriate in underwater environments due to large propagation delay, low communication bandwidth, and high error probability. Thus, we focus on redundancy-based transport schemes in this paper.

Abstract Underwater sensor networks (UWSNs) have been proposed for many location-dependent applications such as oceanographic data collection, pollution monitoring, mine reconnaissance, etc. Accurate node localization plays an important role in realizing the potential gains of these applications.

Abstract—Due to the lossy nature of wireless links, it is difficult to determine if packet losses are due to wireless-induced effects or from malicious discarding. Many prior efforts on detecting malicious packet drops rely on evidence collected via passive monitoring by neighbor nodes; however, they do not analyze the cause of packet losses. In this paper, we ask:(a) Given certain macroscopic parameters of the network (like traffic intensity and node density) what is the likelihood that evidence exists with respect to a transmission?

Abstract In this paper, by establishing the probability models, we systematically and comprehensively analyze the roles of the packet retransmission, the block retransmission, and the erasure coding in the reliable transport of wireless sensor networks. And as well as the three kinds of packet level schemes, we also consider the effect of two kinds of bit level strategies, CRC and FEC.

Abstract Networked systems have benefited from unprecedented growth in hardware capabilities, but, as we move closer to the end of the Moore's law era, future networked systems are likely to be more constrained by hardware capabilities than they have been in the past. We take the position that the networking community should, in response to this development, proactively and systematically develop networking roadmaps, which attempt to predict how trends in hardware capabilities will impact networked systems.

Abstract In social swarming applications, participants equipped with 3G and WiFi-capable smart phones are tasked to provide reports (possibly voluminous ones that include full-motion video) about their immediate environment to a central coordinator. In this paper, we consider the problem of timely delivery of these reports: each report has an associated deadline and the goal of the system is to retrieve as many reports as possible (or retrieve the most valuable reports), while satisfying each report's deadline.

Abstract As the most important issue in wireless sensor networks, power saving is catching researchers' great attentions all the time. Among several power saving strategies, one of the best methods is to make unused components inactive whenever possible, ie applying sleep scheduling schemes to sensors.

Abstract To improve the two deficiencies of the Self-Correcting Time Synchronization (SCTS) mechanism, we propose a Kalman filter based Advanced SCTS (ASCTS) mechanism in this letter. We prove and explain the close relationship between the basic phase locked loop (PLL) employed by SCTS and the Kalman filter employed by ASCTS. An experimental platform with eight GAINS-3 nodes is used to evaluate the performance.

Abstract With the advent of smartphone technology, it has become possible to conceive of entirely new classes of applications. Social swarming, in which users armed with smartphones are directed by a central director to report on events in the physical world, has several real-world applications: search and rescue, coordinated fire-fighting, and the DARPA balloon hunt challenge.