This letter extends the existent MPL (Max-Plus Linear) state-space representation and proposes a new form that can account for both capacity and order constraints. It is often essential to consider these factors when applying the MPL approach to scheduling problems for production or transportation systems. The derived form is a type of augmented state-representation and can contribute to obtaining the earliest start and completion times for processes in installed facilities.

A multi-input erasure channel is defined as the J(J+1) discrete memoryless channel, for which we study a capacity formula, through the method by Muroga. We first give a simpler capacity formula for the multi-input erasure channel with no cross probability. Next we give an upper bound to the capacity for the general case. Finally we remark that the upper bound is actually the capacity when the cross probability is small.

Multilink MIMO technique is a promising technology for cellular networks with a guaranteed quality-of-service. It will provide high capacity and wide coverage. We evaluated the downlink performance of the multilink MIMO system from the perspective of quality-of-service. The presence of Rayleigh fading, shadowing, and path loss was assumed. To evaluate the proposed system, we developed a performance measure for MIMO cellular system. The measure is ergodic capacity taking into account area coverage. Our numerical results show that the area coverage of proposed multilink MIMO system is greatly improved compared with that of the conventional singlelink MIMO system. Using the proposed measure, we also found that the multilink MIMO system could achieve high capacity with guaranteed QoS for a wide coverage.

An adaptive subcarrier allocation (SA) algorithm is proposed for both the enhancement of system capacity and the practical implementation in a clustered OFDM system. The proposed algorithm is based on the two dimensional comparison of the channel gain in both rows and columns of the channel matrix to achieve higher system capacity. Simulation results demonstrate that the proposed algorithm outperforms the SA algorithm based on only one dimensional comparison in terms of system capacity, and furthermore, it performs as well as the optimal SA algorithm at relatively low computational cost.

The paper describes a low complexity tree-structure based user scheduling algorithm in an up-link transmission of MLD-based multi-user multiple-input multiple-output (MIMO) wireless systems. An M-branch selection algorithm, which selects M most-possible best branches at each step, is proposed to maximize the whole system sum-rate capacity. To achieve the maximum capacity in multi-user MIMO systems, antennas configuration and user selection are preformed simultaneously. Then according to the selected number of antennas for each user, different transmission schemes are also adopted. Both the theoretical analysis and simulation results show that the proposed algorithms obtain near optimal performance with far low complexity than the full search procedure.

MIMO systems using a space division multiplexing (SDM) technique in which each transmit antenna sends an independent signal substream have been studied as one of the successful applications to increase data rates in wireless communications. The throughput of a MIMO channel can be maximized by using an eigenbeam-SDM (E-SDM) technique, and this paper investigates the practical performance of 22 and 44 MIMO E-SDM based on indoor measurements. The channel capacity and bit error rate obtained in various uniform linear array configurations are evaluated and are compared with the corresponding values for conventional SDM. Analysis results show that the bit error rate performance of E-SDM is better than that of SDM and that E-SDM gives better performance in line-of-sight (LOS) conditions than in non-LOS ones. They also show that the performance of E-SDM in LOS conditions depends very much on the array configuration.

A numerical hybrid method for analyzing the wireless channel of Multiple-Input Multiple-Output (MIMO) communication system is proposed by combining of the method of moments (MoM) and the finite difference time domain (FDTD) method. The proposed method is capable of investigating a more practical MIMO wireless channel than the conventional methods, and CPU time is much less than that of the FDTD method in analysis of spatial statistical characteristics of received signals. Based on the channel transfer matrix obtained by the proposed method, the wall effect on indoor MIMO channel capacity are investigated with consideration of received power, Ricean K-factor and effective degrees of freedom (EDOF) of multipaths by changing the wall locations and material.

A lossless data embedding method that inserts data in images in the spatial domain is proposed in this paper. Though a lossless data embedding method once distorts an original image to embed data into the image, the method restores the original image as well as extracts hidden data from the image in which the data are embedded. To guarantee the losslessness of data embedding, all pixel values after embedding must be in the dynamic range of pixels. Because the proposed method modifies some pixels to embed data and leaves other pixels as their original values in the spatial domain, it can easily keep all pixel values after embedding in the dynamic range of pixels. Thus, both the capacity and the image quality of generated images are simultaneously improved. Moreover, the proposed method uses only one parameter based on the statistics of pixel blocks to embed and extract data. By using this parameter, this method does not require any reference images to extract embedded data nor any memorization of the positions of pixels in which data are hidden to extract embedded data. In addition, the proposed method can control the capacity for hidden data and the quality of images conveying hidden data by controlling the only one parameter. Simulation results show the effectiveness of the proposed method; in particular, it offers images with superior image quality to conventional methods.

In DS-CDMA cellular communications systems, the single frequency reuse can be utilized. Since large other-cell interference is produced, the well known soft handover or site diversity must be used. If the single frequency reuse is not utilized to avoid the other-cell interference, we will face the frequency allocation problem, similar to FDMA systems. In this paper, a DS-CDMA cellular system using band division is proposed. The available wide frequency band is divided into several narrow frequency bands and the different frequency bands are allocated to adjacent cells so as to avoid the large other-cell interference. For the frequency allocation, the channel segregation distributed channel allocation (CS-DCA) algorithm is applied. The link capacity is evaluated by computer simulation.

Antenna array is essential factor for multiple- input multiple-output (MIMO) wireless systems. Since the antenna array is composed of closely spaced elements, the mutual coupling among the elements cannot be ignored for the best performance of the array. Mutual coupling affects the MIMO channel, so the performance of a MIMO system, including channel capacity and diversity, varies with the degree of mutual coupling. The effect of mutual coupling is a function of the antenna load impedance. Therefore, designing an optimal element-matched array for a MIMO system requires consideration of the optimal matching condition for the array elements, the one that maximizes the channel capacity. We evaluated the effects of mutual coupling with various matching conditions in dipole arrays, and investigated their effects on the path correlation and channel capacity of MIMO systems. Simulation showed that the conventional conjugate matching of each element is still suitable for closely spaced elements except when the separation is about less than 0.1λ. Theoretical consideration of the received power of a closely-spaced-element array is also provided to show the effects of mutual coupling.

The effects of wall reflection on indoor MIMO channel capacity are statistically investigated with consideration of the average received power, the effective degrees of freedom (EDOF) of multipaths and the eigenvalues of transfer channel covariance matrix. It is found that the stronger wall reflection can lead to higher MIMO channel capacity.

In this letter, we propose two different joint transmit and receive antenna subset selection schemes for multiple-input multiple-output (MIMO) systems on the basis of capacity maximization criterion. We assume that perfect channel state information (CSI) is known at the receiver but unknown to the transmitter. As the selection signaling is perfectly fed back to the transmitter, we propose a flexible two-step selection algorithm (TSSA) in practical MIMO channel scenarios. Computer simulations show that TSSA can maximize the capacity at low computation cost in most scenarios. It performs well in terms of capacity, computational complexity and flexibility. Furthermore, we propose a simplified algorithm based on the correlation matrix when the channel correlation information (CCI) is known to the transmitter. Simulation results show that the proposed correlation matrix based selection algorithm is only slightly inferior to an optimal selection algorithm.

This paper presents an admission control technique for multi-carrier systems with an FRF(frequency reuse factor) of 1. The FRF of 1 is very attrative for more improved channel throughput but the forward link capacity is rapidly decreased at the cell boundary region due to the increase in the ICI(InterCell Interference). By measuring a region-based channel capacity and deriving a closed form of blocking probability, a QoS(Quality of Service) maintenance technique and mobility model can be acquired. In the simulation, the proposed scheme demonstrates a blocking probability reduction of up to 40% compared to the cell-based link capacity scheme.

This paper presents a numerical analysis of reverse link capacity by obtaining a closed form of ICI (InterCell Interference) over OFDM (Orthogonal Frequency Division Multiplexing)-based broadband wireless networks. In the analysis, shadowing factors are taken into account for determining the home BS (Base Station) of each MS (Mobile Station) over multicell environments. Under the consideration, a more accurate analysis of link capacity can be performed compared to Gilhousen's approximation. In the numerical results, it turns out that the actual interference is lower than Gilhousen's approximation with a decrease of around 20% in the interference.

Independent shadowing losses are often assumed for evaluating the link capacity of direct sequence code division multiple access (DS-CDMA) cellular system. However, shadowing losses may be partially correlated since the obstacles surrounding a mobile station block similarly the desired signal and the interfering signals. In this letter, we discuss how the shadowing correlation impacts the reverse link capacity of a power-controlled DS-CDMA cellular system, by numerical analysis.

The Erlang capacity of multi-service multi-access systems supporting several different radio access technologies was analyzed and compared according to two different operation methods: the separate and common operation methods, by simultaneously considering the link capacity limit per sector as well as channel element (CE) limit in a base station (BS). In a numerical example with GSM-like and WCDMA-like sub-systems, it is shown that we can get up to 60% Erlang capacity improvement through the common operation method using a near optimum so-called service-based user assignment scheme when there is no CE limit in BS. Even with the worst-case assignment scheme, we can still get about 15% capacity improvement over the separate operation method. However, a limited number of CEs in BS reduces the capacity gains of multi-service multi-access systems in both the common operation and separate operation. In order to fully extract the Erlang capacity of multi-service multi-access systems, an efficient method is needed in order to select a proper number of CE in BS while minimizing the equipment cost.

Secret key agreement is a procedure for agreeing on a secret key by exchanging messages over a public channel when a sender, a legitimate receiver (henceforth referred to as a receiver), and an eavesdropper have access to correlated sources. Maurer [6] defined secret key capacity, which is the least upper bound of the key generation rate of the secret key agreement, and presented an upper and a lower bound for the secret key capacity. The advantage distillation capacity is introduced and it is shown that this quantity equals to the secret key capacity. Naive information theoretical expressions of the secret key capacity and the advantage distillation capacity are also presented. An example of correlated sources, for which an analytic expression of the secret key capacity can be obtained, is also presented.

Effects of wall material on the channel capacity of an indoor multiple input multiple output (MIMO) system are investigated using a hybrid technique of the method of moments (MoM) and the finite difference time domain (FDTD) method with consideration of the Ricean K factor and the effective degrees of freedom (EDOF) of multiple paths.

In this letter, we elucidate the ergodic capacity of multiple-input multiple-output (MIMO) systems with M-ary phase-shift keying (MPSK) modulation and time-multiplexed pilots in frequency-flat Rayleigh fading environment. With linear minimum mean square error (LMMSE) channel estimation, the optimal pilots design is presented. For mathematical tractability, we derive an easy-computing closed-form lower bound of the channel capacity. Based on the lower bound, the optimal power allocation between the data and pilots is also presented in closed-form, and the optimal training length is investigated by numerical optimization. It is shown that the transmit scheme with equal training and data power and optimized training length provides suboptimal performance, and the transmit scheme with optimized training length and training power is optimal. With the latter scheme, in most situations, the optimal training length equals the number of the transmit antennas and the corresponding optimal power allocation can be easily computed with the proposed formula.

In this letter, we investigate the sum-rate capacity of a power-controlled multi-user distributed antenna system (DAS) with antennas deployed symmetrically on a circle. The sum-rate capacity, when divided by user number, is proved to converge to an explicit expression as user number and antenna number go to infinity with a constant ratio. We further show how this theoretical result can be used to optimize antenna deployment. Simulation results are also provided to demonstrate the validity of our analysis and the applicability of the asymptotic results to a small-scale system.