Implicit Sleep Mode Determination in Power Management of Event-driven Deeply Embedded Systems
(2008)
MLMAC-UL and ECTS-MAC - Two MAC Protocols for Wireless Sensor Networks with Unidirectional Links
(2009)
Today's applications and services become more dependent on fast wireless communication, for the upcoming years data-rate demands of 100Gbit/s can be easily expected. However, fulfilling that demand is a task which cannot simply be solved by upscaling existing technologies. While most of the research tackles the challenges regarding the transmission technology from the physical layer up to base-band processing, we focus on the challenges concerning the handling of that vast amount of data. The overall goal is to bring together the transmission technology with the operating system to create a suitable end-to-end communication solution.
In this paper we argue that communication can be understood as a soft-realtime problem and how that helps introducing parallelism into protocol-processing.
Currently, new storage technologies which unite the latency and byte-addressability of DRAM with the persistence of disks are being developed. This non-volatile memory (NVRAM) may start a software revolution. Traditionally, software was developed for two levels of storage and NVRAM reduces the hierarchy to a single-level store. Current research projects are already exploring the potential of NVRAM, but they face a challenge when they want to evaluate the performance: The new hardware is not yet available.
In this paper, we discuss why benchmark results which are gained on existing DRAM are insufficient for a prediction of the performance on NVRAM. Either existing instructions have to be changed or new ones have to be introduced. We further show that the bochs emulator can be used to build systems which resemble NVRAM, to predict the NVRAM's consequences, and it even allows a comparison of algorithms for NVRAM.
Experiments have shown that the number of asymmetric and unidirectional links often exceeds the number of bidirectional ones, especially in the transitional area of the communication range of wireless sensor nodes. Still, most of today’s routing protocols ignore their existence or try to remove their implications. Also, links are not stable over time, and routes become unusable often, resulting in a need for new routing protocols that can handle highly dynamic links and use unidirectional links to their advantage. At Sensorcomm 2014, we presented BuckshotDV, a routing protocol which is resilient against link fluctuations and uses the longer reach of unidirectional links to increase its performance. Furthermore, its distance vector nature makes it scalable for large sensor networks. This paper is an extended version which adds some implementation details and the evaluation of BuckshotDV in two more application scenarios.
Experiments with wireless sensor networks have shown that links are often asymmetric or unidirectional. This represents a serious problem for many routing protocols, which often depend on bidirectional links. Routing protocols that can use unidirectional links often induce a high overhead. To overcome this problem we introduced Unidirectional Link Triangle Routing, a routing protocol, which uses neighborhood information, gathered actively or passively, to route around unidirectional links. In this paper, we describe Unidirectional Link Triangle Routing in further detail and present additional evaluation results from different application scenarios.
Experiments with wireless sensor networks have shown that asymmetric and unidirectional links do not only exist, but are indeed quite common. Still, many people argue that the gain in connectivity is not worth the effort of making them usable for routing protocols. In this paper, we follow the opposite approach and introduce Unidirectional Link Triangle Routing, which reduces the overhead and, therefore, makes unidirectional links usable on the routing layer.