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The upcoming standard for wireless LANs-DFWMAC 1 developed by the IEEE 2 802.11 working group consists of two parts-the distributed coordination function DCF that is based on a contention scheme and the point coordination function PCF based on a contention free scheme. The DCF is CSMA/CA like access protocol with several extensions. In this paper, following(More)
The distributed coordination function (DCF) in the upcoming standard for wireless LANs IEEE 802.11 is based on a CSMA/CA like access protocol. The collision avoidance part applies a rotating backoff window mechanism, that causes unequal collision probability distribution depending on the position of the selected slot within the contention window. We present(More)
The distributed coordination function that is used as the access scheme for asyn-chronous traffic within the upcoming standard for wireless LANs IEEE 802.11 optionally applies the RTS/CTS message exchange to solve the 'hidden terminal' scenario. In this paper, following a general discussion of the mechanism and its problems, we show the effectiveness or(More)
The power consumption of a wireless NIC is a crucial issue because wireless nodes are often constrained by the battery due to strict requirements regarding weight and size. In the paper, we present power consumption measurement results of an Aironet PC4800 PCMCIA wireless interface which is based on Intersil's PRISM I 802.11 11 MBit/s chipset. Thereby, we(More)
When investigating complex communication protocols and a large number of stations using discrete event simulation, it is of great interest to keep the number of necessary simulation events low, since this number directly translates into simulation runtime. One important target for optimizations is the packet or frame exchange over an underlying transmission(More)
×ØÖÖ BLOCKINØ Mobile communication systems like hand-helds and laptops still suffer from low operation time due to limited battery capacity. We exploit the relative new approach of protocol harmonization to extend the time between battery charges in mobile devices using an IEEE 802.11 network interface. Many known energy saving mechanisms only concentrate(More)
— This study investigates the potential of using transmission power control in wireless packet networks with differing number of hops between source and destination. Here we exploit the benefits of power control in the context of multi-hop wireless ad hoc type networks with a distributed media access control. For our investigations we choose several general(More)
Continuous monitoring and analyzing of vital signs is the key for detecting at an early stage when a patient's state of health changes to the worse, thereby preventing emergency cases, which are harmful to the patient and costly for the health care system. The BASUMA project is concerned with developing an energy-efficient and robust system-on-chip platform(More)