In this paper, we derive the closed-form expressions of the probability distribution function (PDF) and cumulative distribution function (CDF) of the ratio of an unordered eigenvalue to the trace of a complex central Wishart matrix. Using the random matrix result, we study the eigenvalue-based spectrum sensing algorithm for cognitive ratio. We apply the goodness of fit test to the ratio of an unordered eigenvalue to the trace of the sample covariance matrix. Finally, we compare the performances between the proposed algorithm and the well-known eigenvalue-based spectrum sensing algorithms in cooperative systems.

A multi-beam method is used in satellite communication systems, etc. A conventional method generates beams for fixed directions or separately directions. Some detection systems require changing directions of multi-beams during an operation for an emitter moving. And, these beams fill arbitrary area existing emitter. In the area, beams have gain required an emitter detection processing.

We propose a calculation technique of beam directions for emitter detection. Multi-beams calculated directions realize the area with the gain.

The conventional shunt-type asymmetric artificial network (AAN) has a critical drawback in that the measuring receiver reading is not proportional to the common-mode disturbance current flowing in the network cable of the equipment under test. To cope with this defect, the present paper theoretically proposes an improvement to the shunt-type AAN. First, circuit analysis is performed to express the AAN common-mode impedance and LCL in terms of the circuit parameters. Then, on the basis of this analysis, an improved shunt-type AAN that satisfies the fundamental requirements is designed and proposed. SPICE simulation demonstrates that the characteristics of the proposed AAN show extremely good agreement with the CISPR specifications.

High dynamic range (HDR) images have been developed to have almost the same dynamic range as human eye, but the huge amount of data brings a problem in storage and transmission. To compress HDR images, an efficient coding method using logarithmic transformation had been proposed in [4]. In this letter, we improve the logarithmic transformation and then derive the optimal parameter to minimize the coding error in HDR region. It is experimentally confirmed that the improved coding method has less coding error in HDR region than other existing methods.

This letter presents an improvement technique for a false alarm probability in simple weighted diversity combining for cyclostationarity detection based spectrum sensing. Although traditional simple weighting techniques can improve a performance of the spectrum sensing, the technique causes an error of false alarm probability between an obtained and designed value. The reason is that the technique requires two types of statistics and both probability density function (PDF) are different. The presented weighting technique makes these PDF matches and the degradation of the signal detection performance for the presented can be ignored. Simple theoretical analysis and numerical examples are shown to validate the effectiveness of the presented.

Packet losses significantly degrade TCP performance in high latency networks. This is because TCP keeps transmission rates low while the lost packets are recovered. To prevent this problem, retransmissions must be kept as low as possible. Therefore, we propose a scheme to apply FEC technology to the entire TCP operation in order to prevent degradation of transmission rates as well as improve throughput. Since a simple application of FEC technology might not work effectively, we consider the ways to control the return of ACKs and redundancy level. We show the effectiveness of this approach through simulation evaluations.

This paper compares performance of index modulation (IM) based OFDM to a more flexible version of OFDM, known as OFDM with multiple constellations (OFDM-MConst). To deliver the same spectral efficiency as in the IM-based OFDM, the OFDM-MConst employs different constellations in different subcarriers. The performance comparison between IM-based OFDM and OFDM-MConst is done for both cases of “no precoding” and “with precoding” of data symbols. Thanks to the multipath diversity gain achieved with precoding and enjoyed by all the information bits, the precoded-OFDM-MConst is shown to significantly outperform precoded-IM-based-OFDM systems over frequency-selective Rayleigh fading channels.

A 2 × 2 circularly polarized array antenna for X-band applications is proposed in this letter. A new technique is employed to attain circular polarization by means of linear polarization patches. Two orthogonal modes with quadrature phase shift is achieved by making two patches quarter wavelength ahead and orthogonal with respect to other two patches. The feed network of the array is designed using both-sided MIC technology to overcome the impedance matching problem of conventional feed networks. A 3-dB axial ratio bandwidth of 1.41% is obtained and antenna gain is around 6.36 dBic.

We propose a bandwidth allocation technique for accommodating a time division duplex mobile base station (TDD-BS) and a secondary system in a TDM-PON. Operating availability is confirmed with essential three types of TDD configuration taken from the seven types described by the Third Generation Partnership Project (3GPP) standardization group. We evaluate the latency of the TDD-BS and the throughput of the secondary system. We report that the TDD-BS signal is forwarded in less than about 50 µs and is unaffected by the secondary system. The throughput of the secondary system is improved compared with that of the conventional technique.

This paper proposes a minimum mean square error-frequency domain equalization (MMSE-FDE) method for training sequence inserted orthogonal frequency division multiplexing (TS-OFDM) signal under higher mobile environments. The salient features of proposed method are to enable the acquisition of frequency diversity gain by using an enhanced channel impulse response (CIR) matrix and to enable the reduction of complexity by using a fast algorithm for inverse matrix calculation. From the simulation results, this paper confirms that the proposed MMSE-FDE method can achieve better bit error rate (BER) performance than the conventional MMSE-FDE methods with keeping lower complexity under higher mobile environments.

This letter proposes continuous beamforming space division multiple access (CB-SDMA) on massive antenna systems for wireless entrance (MAS-WE). Entrance base station hosts an individual baseband signal processing unit for each relay station and continuously applies beamforming weights to transmission/reception signals. It yields virtual point-to-point type backhaul links so radio resource control messages and complicated multiuser scheduling are not required; medium access control is very simple. A computer simulation examines the acceptable CB number and expected throughput performance with given offered load.