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...kernel. SOS’s typed communication protocols were inspired partially by SPIN [2], which makes kernel extensions safe through the use of type safe languages. 2.2 Sensor Network Operating Systems TinyOS =-=[8]-=- is the de facto standard operating system for sensor nodes. TinyOS is written using the NesC language [7] and provides an event driven operating environment. It uses a component model for designing s...

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..., then code updates would have to be done every 162 minutes for TinyOS and SOS to have identical energy consumption. However, most of the real sensor network deployments have a duty cycle of about 1% =-=[17]-=-. If we assume that the Surge application is active for one minute every hour (dropping the duty cycle to 1.67%) to sample and transmit data to the base station, then the 536 seconds of active CPU tim...

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...only variation between the three systems is due to the differences in the protocols for code dissemination. The medium access delay depends on MAC protocol, but this is identical in the three systems =-=[18]-=-. Finally, packet transmission time depends upon the packet size being transmitted; this is different by a handful of bytes in the three systems, causing a propagation delay on the order of 62.4 µs pe...

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... operating systems, effectively prioritizes embedded system constraints over general-purpose OS functionality. TinyOS consists of a rich collection of software components written in the NesC language =-=[7]-=-; these components range from low-level parts of the network stack to applicationlevel routing logic. Components are not divided into “kernel” and “user” modes, and there is no memory protection, alth...

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...be viewed as basic hardware abstractions while modules provide both higher level system management services and applications. Two examples of this are the Mach [19] operating system and the Exokernel =-=[5]-=-. Mach modularizes low layer kernel services to allow easy customization of the system. The Exokernel uses a minimal hardware abstraction layer upon which custom user level operating environments can ...

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... previously difficult or costly to observe. Sensor nodes can be located far from any networked infrastructure and easy human accessibility, anywhere from the forest canopy [12] to the backs of zebras =-=[11]-=-. Due to the difficulty and expense of maintaining such distant nodes, wireless sensor networks are expected to be both autonomous and long-lived, sup∗ This paper is based on research funded in part f...

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...both microbenchmarks and application-level benchmarks of Surge, a well-known multihop data acquisition program. Comparisons of Surge versions running on SOS, TinyOS, and Maté Bombilla virtual machine =-=[13]-=- show comparable CPU utilization and radio usage; SOS’s functionality comes with only a minor energy cost compared to TinyOS. Evaluation of code distribution mechanisms in the same three systems shows...

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...ically linked at compile time, facilitating resource usage analysis and code optimization such as inlining. However, code updates become more expensive, since a whole system image must be distributed =-=[9]-=-. This paper shows that sensor network operating systems can achieve significantly more dynamic, generalpurpose OS semantics than TinyOS without sacrificing energy efficiency or performance. Our opera...

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...g hardware, but the level of hardware abstraction exported by SOS is lower than that in Mach and higher than that in the Exokernel. SOS’s typed communication protocols were inspired partially by SPIN =-=[2]-=-, which makes kernel extensions safe through the use of type safe languages. 2.2 Sensor Network Operating Systems TinyOS [8] is the de facto standard operating system for sensor nodes. TinyOS is writt...

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...y due to two factors: First and the major factor of the overhead is the interpretation of the high level Maté bytecode in comparison to the native instructions. Second, Maté was executing the Trickle =-=[15]-=- protocol for bytecode updates while TinyOS was executing the Deluge [9] protocol for binary updates. Some variation in the active time is caused due to the differences in the amount of processing tha...

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...e VM architecture that allows developers to build custom VMs on top of TinyOS and is distributed with Bombilla, which demonstrates a VM implementation of the Surge protocol. Sensorware [3] and Agilla =-=[6]-=- are designed to enable mobile agent abstractions in sensor networks. Unfortunately, these approaches can have significant computational overhead, and the retasking of the network is limited by the ex...

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...ammable systems target resource rich devices. Loadable modules in Linux share many properties with SOS, but benefit from running on systems that can support complex symbol linking at run time. Impala =-=[16]-=- implements dynamic insertion of code on devices similar to PDAs, but not the simpler devices targeted by SOS. XNP [4] is a mechanism that enables over the air reprogramming of the sensor nodes runnin...

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... This technique can be used at the component level in SOS and, since changes to the SOS kernel or modules will be more localized than in tightly coupled systems, result in smaller differentials. MOAP =-=[22]-=- is a protocol that has been developed to distribute new node images within a sensor network; it uses XNP to reflash nodes. Deluge [9] is a reliable distribution protocol that is used to disseminate l...

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...lements a simple VM architecture that allows developers to build custom VMs on top of TinyOS and is distributed with Bombilla, which demonstrates a VM implementation of the Surge protocol. Sensorware =-=[3]-=- and Agilla [6] are designed to enable mobile agent abstractions in sensor networks. Unfortunately, these approaches can have significant computational overhead, and the retasking of the network is li...

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...rcing a node to reboot after updates, and installing updates directly into program memory without expensive external flash access. Low overhead solutions using differential patching 2are proposed in =-=[20]-=- and [10]. In these schemes a binary differential update between the original system image and the new image is created. A simple language is used to encode this update in a compressed form that is th...

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... limited by the expressibility of the underlying VM or agent system. SOS occupies a middle ground with more flexibility and less CPU overhead than VMs, but also higher mote reprogramming cost. MANTIS =-=[1]-=- implements a lightweight subset of the POSIX threads API targeted to run on embedded sensor nodes. By adopting an event driven architecture, SOS is able to support a comparable amount of concurrency ...

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...ode to reboot after updates, and installing updates directly into program memory without expensive external flash access. Low overhead solutions using differential patching 2are proposed in [20] and =-=[10]-=-. In these schemes a binary differential update between the original system image and the new image is created. A simple language is used to encode this update in a compressed form that is then distri...

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...y sample phenomena that were previously difficult or costly to observe. Sensor nodes can be located far from any networked infrastructure and easy human accessibility, anywhere from the forest canopy =-=[12]-=- to the backs of zebras [11]. Due to the difficulty and expense of maintaining such distant nodes, wireless sensor networks are expected to be both autonomous and long-lived, sup∗ This paper is based ...

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...lly, packet transmission time depends upon the packet size being transmitted; this is different by a handful of bytes in the three systems, causing a propagation delay on the order of 62.4 µs per bit =-=[21]-=-. The latency of packet delivery at every hop is almost identical in the three systems. The small variations that can be observed are introduced mainly due to the randomness of the channel access dela...

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...ractions. Core kernel functionality can be viewed as basic hardware abstractions while modules provide both higher level system management services and applications. Two examples of this are the Mach =-=[19]-=- operating system and the Exokernel [5]. Mach modularizes low layer kernel services to allow easy customization of the system. The Exokernel uses a minimal hardware abstraction layer upon which custom...

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...m running on systems that can support complex symbol linking at run time. Impala [16] implements dynamic insertion of code on devices similar to PDAs, but not the simpler devices targeted by SOS. XNP =-=[4]-=- is a mechanism that enables over the air reprogramming of the sensor nodes running TinyOS. With XNP a new image for the node is stored into an external flash memory, then read into program memory, an...