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All analytical and simulation research on ad~hoc wireless networks must necessarily model radio propagation using simplifying assumptions. We provide a comprehensive review of six assumptions that are still part of many ad hoc network simulation studies, despite increasing awareness of the need to represent more realistic features, including hills,(More)
Robust high-density subthreshold SRAMs are indispensable for emerging ultra-low power applications such as implantable devices, medical instruments, and wireless sensor networks. Conventional 6T SRAMs in the subthreshold region fail to deliver the density and yield requirements due to the reduced static noise margin (SNM), poor writability, limited number(More)
In the scenario of a natural catastrophe or a terrorist attack, a large number of self-organizing, low-cost sensor devices can be deployed over the affected area. Each device equipped with its own power source, sensor, processing unit and low-power radio, can be imbued with the intelligence to seek out its neighbours and join in a wireless network spanning(More)
Some applications of simulation require that the model state be advanced in simulation time faster than the wall-clock time advances as the simulation executes. This faster than real-time requirement is crucial, for instance, when a simulation is used as part of a real-time control system, working through the consequences of contemplated control actions, in(More)
A voltage scalable 0.26V, 64kb 8T SRAM with 512 cells per bitline is implemented in a 130nm CMOS process. Reverse short channel effect was utilized to improve cell write margin and read performance. A marginal bitline leakage compensation scheme was used during read operation to lower Vmin down to 0.26V. Floating write bitline and read bitline, auto(More)
A number of network simulators are now capable of simulating systems with millions of devices, at the IP packet level. With this ability comes a need for realistic network descriptions of commensurate size. This paper describes our effort to build a detailed model of the U.S. Internet backbone based on measurements taken from a variety of mapping sources(More)
The IEEE 802.11 standard is a widely used protocol for wireless communications. It is a moderately complex algorithm involving collision detection, dynamic backoffs, channel reservations, and acknowledgments. Detailed simulation of 802.11 requires some care, and considerable execution time. We are interested in developing a rapidly executable model of(More)
This paper describes the Scalable Simulation Framework SSF, a discrete event modeling API designed for the construction and simulation of very large networks. SSF can execute detailed simulations of complex topology networks with a million or more concurrent TCPPIP ows. We describe the overall architecture of SSF, the architecture of the network modeling(More)
Computer simulation is the most common approach to studying wireless ad-hoc routing algorithms. The results, however, are only as good as the models the simulation uses. One should not underestimate the importance of <i>validation</i>, as inaccurate models can lead to wrong conclusions. In this paper, we use direct-execution simulation to validate radio(More)
ÐThis paper considers a technique for composing global (barrier-style) and local (channel scanning) synchronization protocols within a single parallel discrete-event simulation. Composition is attractive because it allows one to tailor the synchronization mechanism to the model being simulated. We first motivate the problem by showing the large performance(More)