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A new cross-layer design taking advantage of OFDMA in ad hoc networks is presented. OFDMA technology is exploited at the physical layer to improve data rate through multiuser diversity and to enhance channel throughput by enabling multiple concurrent transmissions over orthogonal subchannels, each consisting of a group of tones or subcarriers. The proposed Subchannel Selection Algorithm (SSA) addresses...
In multi-hop packet radio networks with low mobility, forwarding strategies based on the location of the radios are considered to be quite robust and scalable since they consume less network resources for the exchange and storage of network state information than conventional routing. When such geographical forwarding strategies are used over fading channels, the presence of multiple potential forwarding...
Dynamic allocation of resources to the best link in large multiuser networks offers considerable improvement in spectral efficiency. This gain, often referred to as multiuser diversity gain, can be cast as double-logarithmic growth of the network throughput with the number of users. In this paper, we consider large cognitive networks granted concurrent spectrum access with license-holding users. The...
This paper present the results and performance of angle diversity for direction of arrival (DOA) setup. The 4times4 Butler matrix was been used at transmitter and receiver sides. The 2times2 rectangular patches have been used as a transmitter and receiver medium for wireless transmission. The operating frequency for this measurement is 2.4 GHz in WLAN application. This paper analyze about DOA and...
Polarization diversity is an interesting alternative to space diversity, but the channel characteristics need to be investigated. To evaluate the dual polarized channels, a 2times2 multiple-input-multiple-output (MIMO) wireless testbed has been developed. In addition, a dual polarized microstrip patch antenna array has been designed to be used as the transmitter and receiver in this system. Performance...
In (Zheng, 2003), Zheng and Tse formulated the problem of determining the diversity multiplexing tradeoff for MIMO systems. In their formulation they considered a family of coding schemes {C(rho)} for an M times N MIMO channel where C(rho) denotes the coding scheme corresponding to an SNR of rho. For any coding scheme family with a multiplexing rate of r, i.e., whose rate grows as r log(1 + rho),...
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