Cooperative transmission follows the idea to achieve better reception quality for wireless communication systems by exploiting spatial diversity. We discuss the case where a group of sensor nodes transmit cooperatively and simultaneously identical symbols to a far destination. Doing so, they achieve a higher total transmit power. This is useful to reach destinations when no intermediate relays are able to act as repeater. We discuss this situation under the constraints of low power and low cost hardware and derive an optimal symbol constellation for a M-ary modulation scheme to minimize the symbol error. For this, we assume neither phase nor carrier synchronization between cooperatively transmitting nodes or the receiver yielding an easy to implement system with very low requirements for the participating wireless sensor nodes. Transmitted signals superimpose non-coherently in the receiver which uses only the amplitude information to decode symbols acting as an energy detector. We therefore name this modulation energy shift keying (ESK)

This paper presents an experience report illustrating the design of the uPart tiny low-power sensor network platform: from the analysis phase over the definition of the application, design and construction of hardware, the implementation of the software and network to the application set-up. uPart sensor nodes were given away in the conference badge to 500 voluntary attendees of the Ubicomp 2005. In our demo application, uParts were able to recognize activities of attendees of the Ubicomp 2005 conference. Design was carried out under serve time and budget restrictions. The paper focuses on reporting design decisions and presents tech-nical details of uPart hardeware, firmware and applications. It also shows first qualitative experiences with the run of the system at the conference. The outcome of the paper is a general meta-guideline for designing sensor network systems under similar conditions.

This paper presents a sensor-based, networked embedded system, referred to as the particle computer system. It is comprised of tiny wireless sensor nodes, capable of communication with each other, as well as connectivity with backend, PC-based systems, thereby facilitating software development and data analysis in an integrated systems package. The core design principles of the sensor nodes enable operation in very mobile settings and truly ad-hoc, peer-to-peer interoperation without the intervention of a master or explicit middleware layer. The two main system properties highlighted in this paper are: 1) information distribution to all components within the system and 2) the usage of a common communication language in all system components. This language has been proprietarily developed for the particle system and is known as ConCom. As a result of these system properties, we have found the particle system to be very extensible and applicable in many everyday scenarios. The paper presents insights to the implementation of the particle computer system, including software development and data analysis capabilities, and the overall system integration.

If a mobile computing device knows how it is positioned and oriented in relation to other devices nearby, then it can provide enhanced support for multi-device and multi-user interactions. Existing systems that provide position information to mobile computers are reliant on externally deployed infrastructure, such as beacons or sensors in the environment. We introduce the Relate system, which provides fine-grained relative position information to co-located devices on the basis of peer-to-peer sensing, thus overcoming dependence on any external infrastructure. The system is realised as a hardware/software plug-in, using ultrasound for peer-to-peer sensing, USB to interface with standard mobile devices, and data abstraction and inferencing to map sensor data to a spatial model that maintains both quantitative and qualitative relationships. We present a set of services and applications to demonstrate the utility of the system. We report experimental results on the accuracy of the relative position and orientation estimates, and other aspects of system performance.

Synchronous distributed jam signalling (SDJS) is a new transmission scheme targeted to highly mobile and ad hoc wireless systems. It is based on the synchronous, parallel and superimposing emission of jam signal on the physical layer. SDJS is intended to be implemented as a feature on existing standards. It enables those system with the ability to fast estimate statistical parameters. This paper presents SDJS in general and then focuses on the application to estimate the parameter number of devices in a mobile setting. We studied SDJS and its application through a mathematical model and simulations and proved the idea in a real-world implementation on a mobile network, where we estimated the number of devices in real time (within 5 ms), increasing the estimation speed compared to traditional approaches by factor 1000.