Adaptive cancellation of Es layer interference using auxiliary horizontal antennas

Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.

LOW-COMPLEXITY JOINT BEAMFORMING AND POWER ALLOCA-TION FOR SINR BALANCING IN COGNITIVE RADIO NETWORKS

We consider the Signal-to-Interference plus Noise Ratio(SINR) balancing problem in-volving joint beamfoming and power allocation in the Cognitive Radio(CR) network,wherein the Single-Input Multi-Output Multiple Access Channels(SIMO-MAC) are assumed.Subject to two sets of constraints:the interference temperature constraints of Primary Users(PUs) and the peak power constraints of Cognitive Users(CUs),a low-complexity joint beamforming and power allocation algo-rithm called Semi-Decoupled Multi-Constraint Power Allocation with Constraints Preselection(SDMCPA-CP) for SINR balancing is proposed.Compared with the existing algorithm,the proposed SDMCPA-CP can reduce the number of matrix inversions and matrix eigen decompositions signifi-cantly,especially when large numbers of PUs and CUs are active,while still providing the optimal balanced SINR level for all the CUs.

Performance Analysis of Hybrid MAC Protocol for Cognitive Radio Networks

The rapid growth in demand for broadband wireless services coupled with the recent developmental work on wireless communications technology and the static allocation of the spectrum have led to the artificial scarcity of the radio spectrum. The traditional command and control model (Static allocation) of spectrum allocation policy allows for severe spectrum underutilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a hybrid access scheme based on CSMA/CA and TDMA MAC protocols for use in the TV bands. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that, the proposed schemes protect the primary user from harmful Interference from the secondary user. In terms of delay, it was found that packet arrival rates, data rates and the number of secondary users have significant effects on delay.

Interference Mitigation MAC Protocol for Cognitive Radio Networks

The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a dynamic spectrum access scheme for use in the TV bands which uses cognitive radio techniques to determine the spectrum availability. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that the proposed scheme protects the primary users from harmful interference from the secondary users. In comparison with the 802.11 MAC protocol, the scheme improves spectrum utilization by about 27% while limiting the interference imposed on the primary receiver.

New correlated MIMO radar covariance matrix design with low side lobe levels and much lower complexity

In this paper,a new correlated covariance matrix for Multi-Input Multi-Output(MIMO)radar is proposed,which has lower Side Lobe Levels(SLLs)compared to the new covariance matrix designs and the well-known multi-antenna radar designs including phased-array,MIMO radar and phased-MIMO radar schemes.It is shown that Binary Phased-Shift Keying(BPSK)waveforms that have constant envelope can be used in a closed-form to realize the proposed covariance matrix.Therefore,there is no need to deploy different types of radio amplifiers in the transmitter which will reduce the cost,considerably.The proposed design allows the same transmit power from each antenna in contrast to the phased-MIMO radar.Moreover,the proposed covariance matrix is full-rank and has the same capability as MIMO radar to identify more targets,simultaneously.Performance of the proposed transmit covariance matrix including receive beampattern and output Signal-to-Interference plus Noise Ratio(SINR)is simulated,which validates analytical results.