0163-6804/99/$10.00 © 1999 IEEE ith the increasing demands for mobile multimedia services, future wireless networks will adopt micro/picocellular architectures in order to provide the higher capacity needed to support broadband services under the limited radio spectrum [1]. Due to its flexible bandwidth allocation, efficient multiplexing of bursty traffic, and provision of a wide range of wirel...

In this paper, an analytical traffic model with gamma inter-arrival time and general service time distributions is developed to evaluate the system performance, in terms of the blocking probabilities, in cellular wireless networks. The performance is evaluated with guard channels and compared with that obtained from classical Erlang model. Keywords—Cellular wireless networks, traffic model, per...

In this paper, a mathematical model is proposed to estimate the dropping probabilities of cellular wireless networks by queuing handoff instead of reserving guard channels. Usually, prioritized handling of handoff calls is done with the help of guard channel reservation. To evaluate the proposed model, gamma inter-arrival and general service time distributions have been considered. Prevention o...

This paper investigates the performance of digital pulse interval modulation (DPIM) in the presence of multipath propagation and additive white Gaussian noise. The results for optical power requirements normalised to the average optical power required by the on-and-off keying (OOK) verses the channel normalised delay spread for DPIM without guard band and with guard bands are presented, and are...

To meet the requirement of efficient cancellation of inter symbol interference (ISI) in high data rate transmissions over time dispersive channels block based transmissions are often adopted. This is the case in orthogonal frequency domain multiplexing (OFDM), cyclic prefix based single carrier (CP-SC) and block transmissions with null guard periods (ZP-SC). Guard periods are inserted between t...

What are guard cells? A pair of guard cells surrounds each stoma on the leaf surface. Stomata are important because they regulate the uptake of CO 2 from the atmosphere for photosynthesis and also the loss of water vapour from the plant during transpiration. The aperture of the stomatal pore is controlled by the two guard cells. When the guard cells are fully turgid the pore gapes open, whereas...

In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1...

Previous studies reveal that the pH of the apoplastic solution in the guard cell walls may vary between 7.2 and 5.1 in closed and open stomata, respectively. During these aperture and pH changes, massive K+ fluxes cross the cellular plasma membrane driving the osmotic turgor and volume changes of guard cells. Therefore, we examined the effect of extracellular pH on the depolarization-activated ...

Reactive oxygen species (ROS) mediate abscisic acid (ABA) signaling in guard cells. To dissect guard cell ABA-ROS signaling genetically, a cell type-specific functional genomics approach was used to identify 2 MAPK genes, MPK9 and MPK12, which are preferentially and highly expressed in guard cells. To provide genetic evidence for their function, Arabidopsis single and double TILLING mutants tha...

In this paper we have considered a wireless mobile network with data/voice traffic. The paper, considered two type of channel assignment (1) with guard channel (2) without guard channel. In cellular mobile system, radio channels are very limited and mobility of mobile terminal occurs a phenomenon called handoff. Handoff is defined as process of transferring an ongoing call or data session from ...