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This paper addresses wireless relay networks consisting of a one-source-one-destination pair and N noncooperative relays. An objective of this paper is to analytically derive a closed form of an optimal relay amplifying vector (or matrix) for an amplify-and-forward (AF) wireless relay network under channel uncertainty (CU), jamming, and transmission power constraints at the relays, using the minimum mean square error (MMSE) criterion. In addition, this paper presents an efficient relay-selection strategy using the maximum SNR and minimum MMSE cost function criterions under an adverse wireless communication environment with transmission power constraint at the relays.

In this paper, a two-way amplify-and-forward (AF) wireless relay network consisting of two sources with multiple M antennas and one relay with multiple N antennas is investigated with a self-interference cancelation process. The relay amplifying matrix that has the low computational complexity is optimized under the relay transmit power constraint based on zero-forcing (ZF) criterion with a singular value decomposition (SVD) method. The sum rate behavior is analytically and numerically studied by adopting the derived optimal relay amplifying matrix. Additionally, the system performance is evaluated in relation to the system bit error rate (BER) and sum rate by computer simulation. Numerical results show that the eigen beamforming is more competitive than the equal-gain beamforming for the two-way relaying systems.

In this study, we investigated a comparative work for stochastic optimal controller design for continuous-time, discrete-time and unified decentralized singularly perturbed systems. Two objectives are considered in this paper : The first is to find the reduced-order system from the full-order, decentralized singularly perturbed stochastic system by applying the singular perturbation method, and the second is to find the optimal control and cost by using state feedback and static output feedback controllers when continuous-time, discrete-time and unified stochastic systems are applied. For proving the validity of finding the reduced-order system and the optimal control-optimal cost, we show numerical data for state feedback controller and output feedback controller from the examples of continuous-time, discrete-time and unified system, respectively.

An amplify-and-forward (AF) wireless relay network consisting of a one-source-one-destination node pair and cooperative multiple N relay nodes is proposed in three adverse wireless communication environments, i.e., jamming, node geometry, and channel uncertainty. Based on the minimum mean square error (MMSE) criterion, the optimal amplifying relay matrix in three adverse wireless environments with the relay power constraint is derived. In addition, the MMSE cost function behavior in three adverse environments is analytically investigated using the proposed optimal relay amplifying matrix. Finally, using the cost function value, the relay selection scheme in adverse wireless communication environments is presented, which is the main contribution of this paper

This paper proposes amplify-and-forward (AF) relay matrices for a one-source-one-destination pair and cooperative distributed N relay nodes under three adverse wireless relay communication environments: (1) broadband noise jamming (BNJ), (2) node geometry (NG), and (3) channel uncertainty (CU). The main objective of this paper is to analytically derive the minimum mean square error (MMSE)-based optimal relay amplifying matrix. Another objective of this paper is to analyze the MMSE cost function, relay power usage, and signal component power of the received signal at the destination using the derived optimal relay amplifying matrix. Finally, the impacts on these three wireless communication environments for the wireless relay networks will be observed by presenting bit error rate (BER) performance.

This paper studies channel uncertainty and node geometry influences on a regenerative distributed decode-and-forward (DF) wireless relay network. A network consisting of one-source-one-destination pair and N-multibranch relay nodes without a direct link between the source and the destination is investigated. A new proposed detection scheme employs the maximum ratio combiner (MRC) principle. The new detection scheme is applied at both relay nodes and the destination node, to optimally detect the original transmitted message from the source node. Monte-Carlo simulations were used to evaluate the bit error rate (BER) performance for the regenerative distributed DF wireless relay network using the new proposed MRC scheme.

Decentralized singularly perturbed systems by a unified approach using delta (/spl delta/) operator (Middleton and Goodwin, 1986) is presented for investigating new stability bound under system uncertainties. New unified stability bounds are developed based on the unified Lyapunov matrix equation and singular value analysis. It is shown that the system maintains its stability when new unified bounds are applied. Numerical examples are presented to illustrate the proposed analysis.

An efficient baseband receiver, called zero-IF zero crossing demodulator (ZIFZCD), was recently developed for implementation of digital-FM receiver exploiting inexpensive low-power very large scale integrated (VLSI) or application specific oriented integrated circuits (ASIC). An advantage of the ZIFZCD is that its complexity is much lower, implementation is simpler, and power consumption is smaller than those of the conventional limiter-discriminator integrate and dump (LDI) or cross-differentiate multiply (CDM) FM receivers. However, a disadvantage is that the bit error rate (BER) performance of the ZIFZCD is worse than those of the LDI or CDM especially when small numbers of phase axes were employed. But, the merit of ZIFZCD is reduced complexity, which is inversely proportional to the number of phase axes. An objective of this paper is to improve BER performance of the recently developed ZIFZCD with insignificant additional complexities. The ZIFZCD makes a symbol decision by observing only one symbol period. However, narrowband digital FM signals have memory between symbols due to modulation characteristics and intersymbol interference (ISI) effects of filters. If these memory effects are exploited by taking multiple symbol observations for a symbol decision, then performance can be improved. In this paper, rather than increasing the number of phase axes for BER improvement of ZIFZCD, the sliding window, multiple symbol observation design will be employed for a symbol decision. Thus, the merits of ZIFZCD can be preserved by the sliding-window ZIFZCD design.