Dynamic spectrum allocation (DSA) solutions such as cognitive radio networks (CRNs) have been proposed as a key technology to exploit the frequency segments that are spectrally underutilized. In this paper, the performance of cooperative CRNs has been analyzed under two different operational modes, namely, constant primary user protection (CPUP) and constant secondary user spectrum usability (C...

Interference and delay are considered as the major reasons limiting the capacity and increasing the new call blocking probability in cellular system. In this paper we introduce a novel strategy based on cognitive radio. Cognitive radio is defined as a radio or system that senses its environment and can dynamically and autonomously change its transmitter parameters based on interaction with the ...

In today communication systems the most probable problems are that of channel capacity, jamming and interference or noise. The channel capacity can be maximized by multiplexing the channel. While the jamming problem and for noise reduction the most important technique that we can apply is spread spectrum. That by spreading the spectrum of the original message signal, the impact of noise upon th...

In this paper, we analyze capacity and spectrum utilization of spectrally overlaid systems using single-code CDMA (SC-CDMA) and multi-code CDMA (MC-CDMA) techniques according to varying system parameters. The spectrum utilization defined as maximally achievable total throughput in the overlaid systems is compared with that of the un-overlaid systems. Analytical results show that the dominant pa...

In this paper, a dual-hop wireless backhaul and small cell access network has been exploited with effective spectrum sharing, to provide 1 Gb/s/km ultra high capacity density for 5G ultra-dense network deployments. We develop a Single-State Qlearning (SSQL) based radio resource management algorithm for dynamic spectrum access creating a self-organized network. It intelligently utilizes the inst...

Using a theoretical approach based on random processes, signal processing, and information theory, we study the performance of digital watermarks subjected to an attack consisting of linear shift-invariant "ltering and additive colored Gaussian noise. Watermarking is viewed as communication over a hostile channel, where the attack takes place. The attacker attempts to minimize the channel capac...

s: English and German provided Tables: None Figures: 15 Galley proofs: Please send galley proofs to J. K. Su at the MIT Lincoln Laboratory address given above. Telephone: +1-781-981-4188, fax: +1-781-981-7271, email: [email protected]. Abstract Using a theoretical approach based on random processes, signal processing, and information theory, we study the performance of digital watermarks subjected ...

Radio spectrum is an essential input for delivering mobile communication services. Traditionally blocks of licensed spectrum have been exclusively controlled by its buyer. However, in recent years there has been an increasing focus by regulators on developing policies and practices which ensure a more effi cient utilization of the spectrum resource, among which spectrum sharing is one of the mo...