Emad K. Al-Hussaini

Composite Macroscopic and Microscopic Diversity of Sectorized Macrocellular and Microcellular Mobile Radio SystemsEmploying RAKE Receiver over Nakagami Fading Plus Lognormal Shadowing Channel

This paper presents a generalized model of binary phase shift keying (BPSK) direct sequence code division multiple access (DS/CDMA) macrocellular and microcellular sectorized mobile radio systems over Nakagami fading plus lognormal shadowing channels. RAKE receiver, perfect and imperfect sectorization, voice activity monitoring, microscopic and composite microscopic plus macroscopic diversity are considered. The interrelationships among the number of interfering cells, sectorization degree, sectorization imperfection, voice activity factor, fading parameter, microscopic diversity degree, microscopic plus macroscopic diversity degree and the number of users are considered. Numerical results show that voice activity monitoring and sectorization can reduce multiple access interference (MAI). Furthermore, composite microscopic plus macroscopic diversity system can counteract the fast and slow fading components simultaneously.

Multi-User MIMO Mobile CDMA Uplink System Employing Turbo Coding and Joint Detection Through a Multipath Rayleigh Fading Channel

In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitter, the information bits are Turbo coded, then interleaved and passed through a serial-to-parallel converter. The channel is assumed bad urban suffering from multipath Rayleigh fading resulting in inter-symbol and multiple access interferences (ISI and MAI). At the front-end of the receiver, a number of receiving antennas are used followed by a joint multi-user estimator based on the Minimum Mean Square Error Block Linear Equalizer (MMSE-BLE).Computer simulations demonstrate a significant performance improvement in both single user and multi-user cases.

Performance of the decorrelator receiver for DS-CDMA mobile radio system employing RAKE and diversity through Nakagami fading channel

Multiple-access interference (MAI) and multipath fading are two of the most significant factors limiting the capacity and performance of direct-sequence code-division multiple-access (DS-CDMA) systems. In this paper, synchronous multiuser receivers that combine antenna diversity, RAKE reception, and a multipath decorrelator for MAI cancellation are analyzed in a Nakagami faded environment using a maximal ratio combiner or a selection combiner. A coherent binary phase-shift keying employing DS-CDMA is considered. Arbitrary branch correlation is also considered for any diversity order in the case of identical severity fading on the branches.

Decentralized CFAR signal detection

Abstract The concepts of distributed nonparametric generalized sign and cell averaging (CA) CFAR detection with data fusion have been developed. In both cases L sweeps are assumed to be processed. The local decisions are transmitted from each detector to the fusion center. The detectors are identical. The overall decision is obtained on the basis of the k -out-of- N fusion rule. The signal distribution is the chi-square-fluctuating target model. Closed-form expressions for the probability of detection ( P D ) and the probability of false alarm ( P F ) for a Gaussian noise background are derived. The detection performance of the distributed system is determined for a finite and infinite number of detectors assuming that each detector processes a finite number of sweeps.

Diversity Reception of an Asynchronous Blind Adaptive Multiuser Detector Through Correlated Nakagami Fading Channel

In this paper, blind adaptive multiuser detection (MUD) technique is developed for uplink transmission in multiuser space diversity DS-CDMA system to overcome multipath fading effect and multiple access interference. The system consists of a space diversity, a precombining blind adaptive detector (PBAD), and a weight adaptation technique based on the minimization of the mean output energy (MOE). The bit error rate (BER) performance of this receiver for asynchronous DS-CDMA signals with independent and correlated antenna branches under Nakagami fading channel for BPSK system is evaluated. It has been seen that the use of antenna diversity can yield substantial improvement in performance even if the correlation between the antenna elements is relatively large (up to 0.795). However, the large correlation values pose a significant reduction in the diversity gain in comparison with the zero correlation situation. It has also been confirmed by simulations that the PBAD provides a significant receiver performance in comparison with the RAKE receiver employing antenna diversity.

Modified Savage and Modified Rank Squared Nonparametric Detectors

A modified form of the basic Savage statistic is considered and the performance of a modified Savage (MS) nonparametric detector using this modified statistic is derived. Also, a detector using a modified rank squared statistic (MRS) is introduced. The asymptotic relative efficiency (ARE) of the detectors is determined for chisquare, Rician, and log-normal signal fluctuations when the background noise is assumed Gaussian. The ARE performance of the generalized sign (GS) and Mann-Whitney (MW) detectors is also determined for these families of fluctuations. The ARE performance of the various detectors is then compared, and the results of a computer simulation are presented in which, for a finite number of samples, the performance of the modified detectors is compared with the performance of the GS and MW detectors. It is shown that when using a large number of reference noise samples, the ARE of the GS and MW detectors, the MRS and RS detectors, and the MS and Savage detectors are 0.75, 0.868, and 1, respectively. It is also shown that when using a finite number of reference noise samples the MS and MRS detectors can give a superior performance to that obtained with the MW detector, and that this is particularly true in the cases in which the degree of signal fluctuation is high.

Selection and MRC Diversity for a DS/CDMA Mobile Radio System through Nakagami Fading Channel

Spatial diversity is an attractive technology for coping with the fadingchannels encountered in mobile communications.In this paper, the bit error rate (BER) is analyzed theoretically fordiversity reception with a RAKE receiver in aNakagami fading environment using either selection or maximal ratio combining.A coherent binary phase-shiftkeying (CBPSK) direct sequence code division multiple access (DS/CDMA) systemis considered. An arbitrary branchcorrelation is also considered for any diversity order in the case ofidentical fading severity on the branches.

Performance of cell-averaging and order-statistic CFAR detectors processing correlated sweeps for multiple interfering targets

Abstract The performances of the cell-averaging (CA) and order-statistic (OS) CFAR detectors processing M correlated sweeps are analysed for the case where one or more interfering target returns are present in the set of reference cells used in estimating the clutter-plus-noise level. Exact expressions are derived for the detection probabilities of these schemes under Rayleigh fluctuating target model. The OS-CFAR performance for that case gives an integral equation which is evaluated numerically. Performances when sweeps are independent can be obtained easily as a special case.

A combined redundancy averaging signal enhancement algorithm for adaptive beamforming in the presence of coherent signal and interferences

Abstract This article compares the redundancy averaged adaptive beamformer with both the optimum interference plus noise rejecter INREJ and the spatially smoothed adaptive beamformer. It is found that redundancy averaged adaptive beamformer is vulnerable to strong signal cancellation particularly in the presence of two or more signal-coherent interferences. Its pattern may not converge to the desired one of mutually uncorrelated sources. A new algorithm is proposed. It executes three main operations on the sample covariance matrix: redundancy averaging, decision about vulnerability to signal cancellation and estimate enhancement. Computer simulations indicated a remarkable performance improvement due to the proposed agorithm.

Performance of offset receiver diversity for GMSK and spread spectrum GMSK with one-bit differential detection using decision feedback in fast Rayleigh channels

This paper introduces the application of three techniques to improve the performance of one-bit differential detection (DD). The Gaussian minimum shift keying (GMSK) modulation technique is employed. The proposed techniques are spread spectrum, offset receiver diversity and decision feedback (DF). A comparative study shows that when applying the direct sequence spread spectrum (DS-SS), the performance is improved by 9.3 dB at a bit error rate (BER) of 10−3 and the processing gain is equal to 10 relative to that given by Elnoubi [IEEE Trans. Veh. Tech. VT-35(1986)162–167]. When using the offset receiver diversity technique, the corresponding relative improvement is 13 dB. When employing both SS and offset diversity at the same BER, 22 and 25.7 dB improvements are attained for DS and frequency hopping (FH), respectively. A further improvement of about 1 dB is obtained when DF is used.