Carlos de M. Cordeiro

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– In November/2004, we witnessed the formation of the first worldwide effort to define a novel wireless air interface 1 standard based on Cognitive Radios (CRs): the IEEE 802.22 Working Group (WG). The IEEE 802.22 WG is chartered with the development of a CR-based Wireless Regional Area Network (WRAN) Physical (PHY) and Medium Access Control (MAC) layers(More)
Research in the physical (PHY) and medium access control (MAC) layers for dynamic spectrum access (DSA) and dynamic spectrum sharing (DSS) is still at its infancy. Aspects such as spectrum sensing, coexistence, measurement and spectrum management, network reliability and QoS support in face of the need to avoid causing harmful interference into incumbents,(More)
– A number of algorithmic and protocol assumptions taken for granted in the design of existing wireless communication technologies need to be revisited in extending their scope to the new cognitive radio (CR) paradigm. The fact that channel availability can rapidly change over time and the need for coordinated quiet periods in order to quickly and robustly(More)
The integration of different technologies with different capabilities and functionalities is an extremely complex task and involves issues at all the layers of the protocol stack. The authors envision an architecture for state-of-the-art heterogeneous multi-hop networks.
– Today, the largest and most desirable portion of the radio spectrum is allocated to licensed services, which has resulted in the well-known profound scarcity of this resource for emerging applications. With the rapid growth of wireless technologies, current spectrum scarcity has become a serious problem as more and more wireless applications compete for(More)
– In this paper we address the issue of spectrum sensing in cognitive radio based wireless networks. Spectrum sensing is the key enabler for dynamic spectrum access as it can allow secondary networks to reuse spectrum without causing harmful interference to primary users. Here we propose a set of integrated medium access control (MAC) and physical layer(More)
– This paper addresses the issue of deafness in directional antennas for wireless ad hoc networks. Deafness is caused when a node X repeatedly attempts to communicate with node Y but is unsuccessful, because Y is presently tuned to some other antenna beam. In this paper, we first outline different factors which contribute to such deafness in directional(More)
— Spectrum sensing is essential to the realization of spectrum agility in cognitive radio (CR) networks. Although fundamental tradeoffs and theoretical limits associated with spectrum sensing have been studied extensively, there have been very few experimental studies focused on building a spectrum " sensor " with commercial off-the-shelf devices. We have(More)
10 Abstract 11 Bluetooth is a radio technology for Wireless Personal Area Networking (WPAN) operating in the 2.4 GHz ISM fre-12 quency band, and allows devices to be connected into short-range ad hoc networks. The Bluetooth medium access con-13 trol protocol is based on the Master/Slave paradigm wherein any communication between slave devices has to go 14(More)