A new synthesis of the geographical distribution of the genus Ananteris Th orell, 1891 (Scorpiones, Buthidae) in Brazil is proposed. Th ree new species, Ananteris chagasi sp. n., Ananteris kuryi sp. n., and Ananteris bernabei sp. n. are described from the States of Bahia, Espírito Santo and Minas Gerais. Only isolated records of Ananteris species where known up to now, for the States of Minas Gerais and Bahia. Th e record of an Ananteris species from the State of Espirito Santo is new. Th e total number of Ananteris species is now raised to 67 and from this, 16 species are found in Brazil. Th e geographical distribution of the genus is considerably enlarged in the country.
The channel availability of cognitive radio is often estimated through a two-state ON/OFF model of primary users' (PUs) behaviour. The ON/ OFF model estimates channel availability with respect to the presence of PUs. Multiple secondary users (SUs) may be aware of channel availability, and try to opportunistically access the channel when it becomes available. Hence, the ON/OFF model may overestimate channel capacity from the perspective of SUs, since the channel could be occupied not only by a resuming PU, but also by contending SUs. Proposed is a joint channel availability estimation through a Markov chain model which takes into account, within a single model, PU behaviour and the SU's carrier sensing with multiple access/collision avoidance contention access, without leading to the state explosion problem. Simulations performed show that the joint channel availability equation is able to estimate channel capacity with mean errors of around 2%.
This paper presents an experimental sectored receiver for infrared wireless networks. The receiver comprises two sectors, each with a switched gain front-end and a signal-to-noise ratio estimator. These are then interconnected with a best-sector selector unit, able to compensate the gain switching characteristics of the front-ends. The circuit has been designed in a 0.8µm CMOS technology.
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