Under heterogeneous radio conditions, Wireless LAN stations may use different modulation schemes, leading to a heterogeneity of bit rates. In such a situation, 802.11 DCF allocates the same throughput to all stations independently of their transmitting bit rate; as a result, the channel is used by low bit rate stations most of the time, and efficiency is low. In this paper, we propose a more ef...

In this paper, we describe a simplified soft-output demapper designed to support coded multiple-input multiple-output orthogonal frequency-division multiplexing-based system utilizing only 3-bit soft information. The IEEE 802.11n standard requires relatively high punctured convolutional code rate of R = 5/6 for spectrally efficient high-throughput data rate settings. In order to extract soft-bi...

Modern wireless devices, such as those that implement the 802.11abg standards, utilize multiple transmission rates in order to accommodate a wide range of channel conditions. The use of multiple rates presents a significantly more complex challenge to ad hoc routing protocols than the traditional single rate model. The hop count routing metric, which is traditionally used in single rate network...

This paper presents a discounted cash-flow approach to an inventory model for deteriorating items with the two-parameter Weibull distribution. According to our proposed model, two shortages are considered: back-orders and lost-sales, in which the back-order rate is a varying function of the time when the shortage happens. In general, the demand rate is a linear function of the selling price...

The buffer allocation problem is an NP-hard combinatorial optimization problem, and it is an important design problem in manufacturing systems. The research proposed in this paper concerns a product line consisting of n unreliable machines with n − 1 buffers and a preventive maintenance policy. The focus of the research is to obtain a better trade-off between the buffer level ...

In IEEE 802.11, the rate of a station (STA) is dynamically determined by link adaptation. Low-rate STAs tend to hog more channel time than high-rate STAs due to fair characteristics of carrier sense multiple access/collision avoidance, leading to overall throughput degradation. It can be improved by limiting the transmission opportunities of low-rate STAs by backoff parameters. This, however, m...

In the past decade, malaria rates have plummeted as a result of aggressive infection control measures and the adoption of artemisinin-based combination therapies (ACTs). However, a potential crisis looms ahead. Treatment failures to standard antimalarial regimens have been reported in Southeast Asia, and devastating consequences are expected if resistance spreads to the African continent. To pr...

In this paper, we study rate allocation for a set of end-to-end communication sessions in multi-radio wireless mesh networks. We propose cross-layer schemes to solve the joint rate allocation, routing, scheduling, power control and channel assignment problems with the goals of maximizing network throughput and achieving certain fairness. Fairness is addressed using both a simplified max-min fai...

A orthogonal decomposition of a general wideband space-time multipath channel is derived assuming antenna arrays at both the transmitter and receiver. Knowledge of channel state information at the transmitter is used to decompose the channel. This decomposition serves as a framework for eeciently managing the degrees of freedom in the space-time channel to trade-oo diversity and throughput. Sig...

Data Centers (DCs) are required to be scalable to large data sets so as to accommodate everincreasing demands of resource-limited embedded and mobile devices. Thanks to the availability of recent high data rate millimeter-wave frequency spectrum such as 60GHz and due to the favorable attributes of this technology, wireless DC (WDC) exhibits the potentials of being a promising solution especiall...