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Available spectrum for wireless communications is a limited resource which gains importance with the increasing demand for mobile communication services with high data rates. Measurements show that assigned frequency bands (FBs) are not used efficiently. One approach for increasing the efficiency in spectrum use is the concept of overlay systems, which can be seen as an enabling technology for cognitive...
With an increased focus on national security and public safety communications, the US Congress revisited its plan to reclaim television broadcaster frequencies to be reallocated and auctioned by the FCC and it specifically allocated a portion of that spectrum for use by public safety. The FCC was charged with the duty of auctioning this spectrum and licensing it to create a public safety network....
In this paper, we introduce and evaluate ScaleMesh, a scalable miniaturized dual-radio wireless mesh testbed based on IEEE 802.11b/g technology- ScaleMesh can emulate large-scale mesh networks within a miniaturized experimentation area by adaptively shrinking the transmission range of mesh nodes by means of variable signal attenuators. To this end, we derive a theoretical formula for approximating...
We consider data-streaming from an access point to multiple receivers, which is modeled as packet erasure channel. A simple network coding is shown to achieve larger rate region than without network coding, using minimal control information. The performance is characterized exactly using state transition graph. The scheme is then mapped to an information theoretic formulation for broadcast channel...
This paper proposes a fast forward medium access control protocol (FFMAC) for quality-of-service (QoS) guarantee in multihop IEEE 802.11s wireless mesh networks with multiple channels. To the best of our knowledge, the proposed protocol is the first one which considers the multihop and multichannel issues simultaneously. It provides higher priority for real-time applications, while remaining the distributed...
In this paper we discuss performance results of a novel real-time closed-loop power amplifier (PA) linearization technique that has originally been proposed by Ahmed and Li. The novel approach performs on-the-fly prediction and measurement of the PA AM/AM and AM/PM non-linearity, stores such non-linear characteristics and calculates their inverse functions in order to pre-distort the base-band amplitude...
In this paper, we propose a cross-layer optimization approach that exploits retransmission diversity in wireless CDMA communications. Conventionally, data packets that are not correctly detected are usually dropped. These dropped packets can be used to help data packet detection. By exploiting all the retransmitted packets, data packets can be correctly detected with higher probability. The proposed...
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