Search

A mobile station in IEEE 802.16e operates power management using sleep-mode operation with one or more connections supporting several applications. After all of the connections of an MS transit into the sleep state, the MS powers down and then goes into an unavailable state without communicating with the serving base station. To improve energy conservation, this letter proposes a new scheduled power-saving mechanism, which schedules sleep-mode operations for connections, which newly initiate sleep-mode, by controlling operating parameters, such as the minimum sleep interval (Tmin) and the maximum sleep interval (Tmax), and the initiation time of sleepmode operations of low quality of service (QoS) connections. Performance results show that the proposed mechanism can reduce the available state of an MS through this scheduling, and thus achieve better energy conservation of the MS than the standard mechanism. [ABSTRACT FROM PUBLISHER]

Performance of the IEEE 802.16 e power management is mainly affected by two operating parameters: the minimum sleep interval (T min) and the maximum sleep interval (T max), in sleep-mode operation. To enhance the performance, this letter proposes a new power saving mechanism, which adaptively controls these parameters by considering the request period of each initiation of awakening (Tint)- The numerical analysis and simulation results show that this mechanism can achieve better energy conservation with reasonable response delay of Medium Access Control (MAC) Service Data Units (SDUs) than the standard operation. [ABSTRACT FROM PUBLISHER]

This letter proposes a new dynamic burst length adjustment mechanism to achieve optimal performance of fiber delay line (FDL) buffers in optical burst switching networks. Our results show that burst blocking probability at an optical node with a fixed length FDL buffer can be kept at minimum under changing traffic conditions using the proposed mechanism. [ABSTRACT FROM PUBLISHER]

A novel all-optical wavelength converter based on the transverse-magnetic (TM)-mode absorption modulation of a Fabry-Perot laser diode (FP-LD) is proposed and demonstrated. An FP-LD shows absorption nulls for TM mode probe beam, which are red-shifted by an additional optical pump injection. Using this, the transmission of the continuous-wave probe beam can be optically controlled and wavelength conversion is, thus, achieved. The proposed scheme is simple and cost-effective, and can be used for very wide-range wavelength conversion. Bit-error-rate measurements at 2.5 Gb/s were performed, and the power penalties of 2 and 6 dB were observed, respectively, for noninverted and inverted wavelength conversion. [ABSTRACT FROM PUBLISHER]

The 802.16e power management helps to increase the lifetime of Mobile Subscriber Stations (MSSs) by reducing their energy consumption, but this reduction results in Medium Access Control (MAC) Service Data Unit (SDU) response delay. Hence, both energy consumption and MAC SDU response delay are important performance metrics; however, they have a trade-off relationship. To guarantee the delay constraints of delay-sensitive applications, operating parameters in sleep-mode operation such as minimum sleep interval, Tmin, and maximum sleep interval, Tmax, should be considered seriously. Especially, large Tmax, results in high MAC SDU response delay. However, in the IEEE 802.16e standard, this point is not given enough attention. In this paper, we first propose a numerical model to determine Tmax based on MAC SDU response delay. Then, we propose a Delay -Guaranteed Energy Saving (DGES) algorithm to minimize energy consumption with a given MAC SDU response delay by finding the optimal Tmax under a fixed Tmin. Our proposed numerical model and DGES algorithm are verified by simulation results. [ABSTRACT FROM AUTHOR]

Microglial cells, the resident immune cells of the spinal cord, become activated in response to peripheral nerve injury. Microglia activation contributes to the development of neuropathic pain. Here we employed microarray analysis of individually collected pools of 10 spinal microglia cells to identify changes of levels and cell-to-cell expression variance of microglial genes during their activation after peripheral nerve injury. The analysis of microglia on postoperative day 1 (POD1) identified miR-29c as a critical factor for microglial activation and the development of neuropathic pain. Early POD1 microglia exhibited a very distinct expression profile compared to late POD7 microglia, possibly leading to the transition from initiation to maintenance of neuropathic pain. We found sample variance patterns that were consistent with the hypothesis that microglia were highly heterogeneous at the level of individual cells, and variation analysis identified 56 microglial genes potentially linked to the maintenance of neuropathic pain which included Gria1. This study provides insights into spinal microglial biology and reveals novel microglial targets for the treatment of neuropathic pain. [ABSTRACT FROM AUTHOR]

We have applied the effective index method to reduce the two-dimensional (2-D) refractive index profile into the 1-D refractive index structure and modified the wave equations to obtain the paraxial wave equations. Then, transverse electric (TE) and transverse magnetic (TM) polarized fields in the curved single-mode planar waveguides are analyzed by using the scalar beam-propagation method (BPM) employing the finite-difference method with a slab structure. The bending loss in bent waveguides is analyzed for optical fields obtained from the BPM and comparisons are made between the loss for the waveguides with various radius of curvature and the refractive index difference. The outward shift of the optical field, which is generated at the connection between a straight and a bent waveguide, is obtained from the results of calculation of location of the maximum optical intensity. The transition loss can be reduced by introducing an optimized inward offset at a straight-to-bend junction. The birefringence for TE and TM polarized fields in bent waveguides is calculated from the phase difference of the optical fields. The wavelength shift due to the birefringence of TE and TM polarized fields in bent waveguides is also calculated. [ABSTRACT FROM AUTHOR]