This paper proposes a cooperative wireless relay network consisting of a one-source-one-destination node pair and N relay nodes in three wireless communication environments, i.e., jamming, node geometry, and channel uncertainty. The main objective of this paper is to analytically derive the optimal cooperative amplify-and-forward (AF) wireless relay matrix under three conditions with the relay power constraint based on the minimum mean square error (MMSE) criterion. Using the derived amplifying relay matrix, the MMSE cost function and achievable rate will be investigated numerically and analytically.

A cooperative amplify-and-forward (AF) wireless relay scheme consisting of M sources, N relays, and L destinations all equipped with a single antenna is studied in this paper. The main objective is to design jointly and iteratively the closed-form of minimum mean square error (MMSE)-based source precode and relay amplifying matrices under a jamming environment with transmit power constraints and aggregate power constraints. With the derived optimal source precode and relay amplifying matrices, the jamming influence on system performance with both transmit and aggregate power constraints is examined numerically by using Monte-Carlo simulations.

This paper presents both cooperative and noncooperative amplify-and-forward (AF) relay networks consisting of a one-source-one-destination pair and N-relays under receiver power constraint (RPC) at the destination. The optimal AF relay amplifying matrices for the relays by minimizing the mean square error are analytically derived. This paper also shows that the performance of the optimum cooperative relay network is identical to that of the optimum noncooperative network, as long as the same receiver power constraint is applied. The purpose of the RPC is to reduce the interference level for users located in neighboring cells. Finally, using the derived optimal relay amplifying matrices, the achievable rate, the pairwise error probability, and the outage probability are investigated.

This paper considers an amplify-and-forward (AF) relay scheme for M-source-M-destination pairs and N relay nodes. Cooperative minimum mean square error (MMSE) strategies for wireless relay networks under both a jamming environment and channel uncertainty with received power constraints at the destination nodes are studied. The main contribution of this paper is the derivation of the MMSE-based amplifying relay matrices (ARMs) under both a jamming environment and channel uncertainty. With the proposed ARMs, the system performance under study is evaluated by observing bit error rate (BER) using Monte Carlo simulations. In addition, it is proven that the proposed ARM is the global optimal ARM.

The omnidirectional mobility of a mobile robot loses significance in motion control, unless the isotropy characteristics of the mechanism is maintained well. This paper investigates the local and global isotropy of an omnidirectional mobile robot with three caster wheels. All possible actuations with different number and combination of rotating and steering joints are considered. First, the kinematic model based on velocity decomposition and the algebraic conditions for the local isotropy are obtained. Second, the geometric conditions for the local isotropy are derived and all isotropic configurations are fully identified. Third, the global isotropy index is examined to determine the optimal parameters in terms of actuation set, characteristic length, and steering link length.

This paper presents a complete isotropy analysis of an omnidirectional mobile robot with three caster wheels. All possible actuation sets with different number and combination of rotating and steering joints are considered. First, the kinematic model of a caster wheeled omnidirectional mobile robot (COMR) having n (3 /spl les/ n /spl les/ 6) actuated joints is obtained without matrix inversion. Second, with the characteristic length introduced, the isotropy conditions of a COMR are derived, which are imposed on two Jacobian matrices. Under the isotropy condition on one Jacobian matrix, three caster wheels should be identical with the length of the steering link equal to the radius of the wheel. Third, depending on the selection of actuated joints, the isotropy conditions on the other Jacobian matrix are examined. The isotropic configurations of a COMR are identified, along with the isotropy loci in the configuration space.

This paper presents the quantitative and geometric analysis on the kinematics of a wheeled mobile manipulator as the serial connection of a mobile platform and a manipulator. Three different modes of operation are considered, including two standalone operations of a mobile platform or a manipulator and one simultaneous operation of two subsystems. First, the well-defined directional manipulability measure of a robot is formulated. Second, the kinematic model of a mobile manipulator is derived and the configuration dependent singularity is analyzed. Third, the directional manipulability of a mobile manipulator is quantified and the effect of serial cooperation is analyzed. Finally, some discussions and conclusion are made.