Brian M. Sadler

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A simple method, based on elementary fourth-order cumulants, is proposed for the classification of digital modulation schemes. These statistics are natural in this setting as they characterize the shape of the distribution of the noisy baseband I and Q samples. It is shown that cumulant-based classification is particularly effective when used in a(More)
II Spectrum Opportunity Identification 5 II-A Spectrum Opportunity and Interference Constraint: Definitions and Implications . . . . . . . . . 5 II-A.1 Spectrum Opportunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II-A.2 Interference Constraint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II-B Spectrum(More)
Most of the radio spectrum relevant to wireless communications is densely allocated by regulators, making it unlikely that the bandwidth requirements of emerging technologies can be met. Actual measurements illustrate, however, that the scarcity is not a result of heavy usage of the spectrum; in contrast, it is merely due to the inefficiency of the static(More)
In this paper we design a cognitive radio that can coexist with multiple parallel WLAN channels while abiding by an interference constraint. The interaction between both systems is characterized by measurement and coexistence is enhanced by predicting the WLAN’s behavior based on a continuous-time Markov chain model. Cognitive Medium Access (CMA) is derived(More)
Signal detection is one application for which dedicated sensor networks have been proposed. Joint signal processing and communication design of such networks has been of great interest recently. We consider new approaches where transmissions can be ordered and halted when sufficient evidence is accumulated. We demonstrate that these approaches require, on(More)
Two major training techniques for wireless channels are time-division multiplexed (TDM) training and superimposed training. For the TDM schemes with regular periodic placements (RPPs), the closed-form expression for the steady-state minimum mean square error (MMSE) of the channel estimate is obtained as a function of placement for Gauss-Markov flat fading(More)
The problem of opportunistic access of parallel channels occupied by primary users is considered. Under a continuous-time Markov chain modeling of the channel occupancy by the primary users, a slotted transmission protocol for secondary users using a periodic sensing strategy with optimal dynamic access is proposed. To maximize channel utilization while(More)
In this work we are concerned with dynamically sharing the spectrum in the time-domain by exploiting whitespace between the bursty transmissions of a primary user, represented by an 802.11b-based wireless LAN (WLAN). For deriving such schemes we need to establish a model of the WLAN's medium access as to predict its behavior accurately. Moreover, a balance(More)