Cooperative diversity represents an effective way of combating multipath fading through inter-terminal cooperation in wireless networks. In this letter, we propose a new participation strategy that increases the chance of cooperation and present the closed-form expression for outage probability. Numerical results demonstrate that new participation strategy improves the outage performance.

This letter presents an extended Pawula F-function for computing the error rate of generalized M-ary phase shift keying (MPSK) system in the presence of phase error, quadrature error, and I-Q gain mismatch over additive white Gaussian noise (AWGN) and fading channels. The extended Pawula F-function conditioned on an instantaneous fading carrier-to-noise ratio (CNR) is derived in the form of the Craig representation.

We propose a new fixed-rate error correction system with a feedback channel. In our system, the receiver transmits a list of positions of unreliable information bits based on the log a-posteriori probability ratios by outputs of a soft-output decoder to the transmitter. This method is just like that of the reliability-based hybrid ARQ scheme. To dynamically select an appropriate interleaving function with feedback information is a key feature of our system. By computer simulations, we show that the performance of a system with a feedback channel is improved by dynamically selecting an appropriate interleaving function.

Internet engineering task force (IETF) has proposed hierarchical mobile IPv6 (HMIPv6) in order to reduce a frequent location registration of a mobile node in mobile IPv6 (MIPv6). All traffics toward a mobile node must be transmitted through a MAP in HMIPv6. This brings unnecessary packet latency because of the increased processing cost of packet at the MAP. At this point, the processing cost of packet at the MAP is influenced by the packet arrival rate for a mobile node, cell mobility rate and the number of mobile nodes in MAP domain. In this paper, we analyze the MAP's performance considering the above elements. For this, we compare total cost of HMIPv6 with total cost of MIPv6 as MAP's capability after we define Markov chain model for performance analysis. Also, we define network's total profit as total cost of MIPv6 minus total cost of HMIPv6. Then, we can find optimal capability of MAP such that total profit has maximum value. Also, we use the blocking probability by the MAP's capability as performance estimation element. As a conclusion, we can observe both HMIPv6's performance by the MAP's capability and optimal capability of the MAP, and blocking probability form a relationship of trade off between them.

We extend the sliding block code in symbolic dynamics to transform J (≥2) sequences of Markov chains with time delays. Under the assumption that the chains are irreducible and aperiodic, we prove the central limit theorem (CLT) for the normalized sums of extended sliding block codes from J sequences of Markov chains. We apply the theorem to the system analysis of asynchronous spread spectrum multiple access (SSMA) communication systems using spreading sequences of Markov chains. We find that the standard Gaussian approximation (SGA) for estimations of bit error probabilities in such systems is the 0-th order approximation of the evaluation based on the CLT. We also provide a simple theoretical evaluation of bit error probabilities in such systems, which agrees properly with the experimental results even for the systems with small number of users and low length of spreading sequences.

This paper studies a multiband mobile communication system to support both high data rate services and wide service coverage, using high and low frequency resources with different propagation characteristics. In the multiband system, multiple frequency bands are managed by a base station and one of the frequency bands is adaptively allocated to a terminal depending on his channel quality. By limiting the low frequency resources to a terminal not covered by the higher frequencies, the presented multiband system can accommodate many terminals providing wide coverage area, as if all radio resources have low frequency. From numerical results, the multiband system can provide wide service coverage area for much larger number of terminals than conventional systems. It is also found that an appropriate balance of multiple frequency resources is essential to achieve high capacity.

Aiming to optimally transmit space-time block codes (STBCs) over distributed antennas (DAs), this paper examines downlink transmit antenna subset selection with power allocation for STBCs in non-ergodic Rayleigh fading channels with receive antenna correlations. Closed-form outage probability is first derived, which is a function of data rate, rate of STBCs, transmit power, large-scale fading (shadowing and path loss), power allocation weights to each DA and receive antenna correlation. However, achieving the optimal power allocation solution is computationally demanding and the use of sub-optimal techniques is necessitated. Assuming feedback of eigenvalues of transmit and receive antenna correlation matrix at the transmitter and accurate channel state information (CSI) at the receiver, an antenna subset selection with sub-optimal power allocation scheme is proposed, whose performance approaches optimal. The effectiveness of this sub-optimal method has been demonstrated by numerical results.

Two dimensional optical fiber measurement system is used to investigate experimentally the arc motion and reignition with four different configurations of quenching chamber in an AC contactor. It demonstrates that the splitter plate arrangement has significant effect on the arc motion in arc quenching chamber, and fixing arc runner in the first and last splitter plates benefits to arc motion, and increase the dielectric recovery strength. The results are very useful to design the quenching chamber in AC contactor with high performance.

In this letter, a more exact analysis scheme for outage probability is proposed for uplink of direct sequence code division multiple access (DS-CDMA) systems. In the previous works, the effect of call admission control (CAC) on signal to interference ratio (SIR) is considered to evaluate the performance of the outage probability for CDMA systems, however, the effect of CAC on system states is not accurately considered. In this letter, we first analyze the system states more exactly by taking the effect of CAC on CDMA system states into account. Then, the exact probability of the outage is derived according to the exact system states. The probability of the system states and the outage of the proposed approximation scheme are compared with the results of the traditional analysis schemes and the computer simulation. Compared with traditional analysis schemes, the numerical results of the proposed analysis scheme is more close to the computer simulation results.

A function approximation based on an orthonormal wave function expansion in a complex space is derived. Although a probability density function (PDF) cannot always be expanded in an orthogonal series in a real space because a PDF is a positive real function, the function approximation can approximate an arbitrary PDF with high accuracy. It is applied to an actor-critic method of reinforcement learning to derive an optimal policy expressed by an arbitrary PDF in a continuous-action continuous-state environment. A chaos control problem and a PDF approximation problem are solved using the actor-critic method with the function approximation, and it is shown that the function approximation can approximate a PDF well and that the actor-critic method with the function approximation exhibits high performance.

A wireless multi-hop virtual cellular network (VCN) was recently proposed to avoid the large peak transmit power, resulting from the high transmission rates expected for future mobile communication systems. In VCN, calls hop through several links to reach the central port, which is the gateway to the network. With the use of a routing algorithm based on the total uplink transmit power minimization criterion, the total transmit power of all the multi-hop links between the mobile terminal and the central port can be significantly reduced, in comparison with the present (single-hop) cellular network. In this paper, an "on-demand" channel assignment strategy, using the channel segregation dynamic channel allocation (CS-DCA) algorithm, is proposed for multi-hop DS-CDMA VCN. Computer simulation is conducted to evaluate the blocking probability performance and make a comparison between the VCN and the present cellular network.

Expressions are presented for the probability of target detection and the measurement accuracy of the detection, taking into account the effects of antenna beam-pointing error. Evaluation of these expressions requires numerical integration, which is computationally expensive. Approximate but analytic and efficient expressions are also presented. Numerical examples are given to present the relative accuracy of our analytic approximations.

This paper presents a view independent video-based face recognition method using posterior probability in Kernel Fisher Discriminant (KFD) space. In practical environment, the view of faces changes dynamically. Robustness to view changes is required for video-based face recognition in practical environment. Since the view changes induce large non-linear variation, kernel-based methods are appropriate. We use KFD analysis to cope with non-linear variation. To classify image sequence, the posterior probability in KFD space is used. KFD analysis assumes that the distribution of each class in high dimensional space is Gaussian. This makes the computation of posterior probability in KFD space easy. The combination of KFD space and posterior probability of image sequence is the main contribution of the proposed method. The performance is evaluated by using two face databases. Effectiveness of the proposed method is shown by the comparison with the other feature spaces and classification methods.

Live streaming is delay sensitive and can tolerate some amount of loss. The QoS Multicast for Live Streaming (QMLS) Protocol, focuses on the characteristics of live streaming. It has been shown to improve the performance of live streaming multicast by reducing the end-to-end packet loss probability. However, the placement of active routers performing the QMLS function has not been discussed. This paper proposes a dynamic method to activate and deactivate routers in order to minimize the number of active routers for each QMLS-packet flow and discusses its parameters. The results of an evaluation show that the proposed method can reduce the number of active routers for each flow and adjust the active routers according to changes in the multicast tree.

The quadrature component unbalance generated by a non-ideal component such as an imperfect 90-degree phase shifter is an inevitable physical phenomenon and leads to performance degradation in a practical coherent M-ary phase shift keying (MPSK) transceiver. In this letter, we present an exact and general expression involving the one- and two-dimensional Gaussian Q-functions for the symbol error rate (SER) of MPSK with I/Q phase unbalance over an additive white Gaussian noise (AWGN) channel. The SER expression provided here offers a convenient way to evaluate the performance of MPSK systems for various cases of practical interest.

In this paper, we define a stopping set of turbo codes with the iterative decoding in the binary erasure channel. Based on the stopping set analysis, we study the block and bit erasure probabilities of turbo codes and the performance degradation of the iterative decoding against the maximum-likelihood decoding. The error floor performance of turbo codes with the iterative decoding is dominated by the small stopping sets. The performance degradation of the iterative decoding is negligible in the error floor region, so the error floor performance is asymptotically dominated by the low weight codewords.

The downlink (base-to-mobile) bit error rate (BER) performance for a mobile user with relatively weak received signal in a multicarrier-CDMA (MC-CDMA) cellular system can be improved by utilizing the site diversity reception. With joint use of MMSE-based frequency domain equalization (FDE) and antenna diversity combining, the site diversity operation will increase the downlink capacity. In this paper, an expression for the theoretical conditional BER for the given set of channel gains is derived based on Gaussian approximation of the interference components. The local average BER is then obtained by averaging the conditional BER over the given set of channel gains using Monte-Carlo numerical method. The outage probability is measured from the numerically obtained cumulative distribution of the local average BER to determine the downlink capacity. Results from theoretical computation are compared to the results from computer simulation and discussed.

In 3G CDMA mobile communication systems, high data rate services are essential for many key applications. When an MS approaches the cell border, link performance is degraded and more power should be allocated to maintain the link performance. Since the maximum available signal power is limited, the link adaptation mechanism may diminish the data rate to maintain link performance. This implies that the valid coverage shrinks when the data rate increases. The shrinking of valid coverage under a predetermined data rate will strongly impact on the reliability of high data rate services. In this work, the encoded bit error probabilities of 3G CDMA mobile communication systems, over large-scale and large-small-scale fading channels, were analyzed based on SGA and SIGA methods. Analytic methods were also proposed to investigate the issues of coverage shrinking and service data rate variations. Furthermore, the outage probability, cell coverage percentage and the staying probabilities of available data rates were well examined. The proposed analytic methods can be applied, as a preliminary research, to the design of cellular-system-related techniques, such as QoS control, available data rate prediction, power reservation, and service adaptation.

This letter considers the signal design problems for quaternary digital communications with nonuniform sources. The designs are considered for both the average and equal energy constraints and for a two-dimensional signal space. A tight upper bound on the bit error probability (BEP) is employed as the design criterion. The optimal quarternary signal sets are presented and their BEP performance is compared with that of the standard QPSK and the binary signal set previously designed for nonuniform sources. Results shows that a considerable saving in the transmitted power can be achieved by the proposed average-energy signal set for a highly nonuniform source.

An FRPA (frequency reuse power allocation) technique by employing the frequency reuse notion as a strategy for overcoming the ICI (intercell interference) and maintaining the QoS (quality of service) at the cell boundary is described for broadband cellular networks. In the scheme, the total bandwidth is divided into sub-bands and two different power levels are then allocated to sub-bands based on the frequency reuse for forward-link cell planning. In order to prove the effectiveness of the proposed algorithm, a Monte Carlo simulation was performed based on the Chernoff upper bound. The simulation shows that this technique can achieve a high channel throughput while maintaining the required QoS at the cell boundary.