초록

The invention provides a method for operating a hybrid automatic repeat request communication system wherein it is determined whether a receiver can process a data packet, and a self-decode request associated with the data packet is sent based on the determination.

대표청구항 ▼

The invention provides a method for operating a hybrid automatic repeat request communication system wherein it is determined whether a receiver can process a data packet, and a self-decode request associated with the data packet is sent based on the determination. ch uses this optical disc. The rep

The invention provides a method for operating a hybrid automatic repeat request communication system wherein it is determined whether a receiver can process a data packet, and a self-decode request associated with the data packet is sent based on the determination. ch uses this optical disc. The reproducing device casts a light beam emitted from a single light source onto the first recording layer or the second recording layer via a single objective lens, discriminates which of the first recording layer and the second recording layer the light beam emitted from the light source is cast on, on the basis of the result of detection of a reflected beam from the first recording layer or the second recording layer, moves the objective lens in a direction parallel to the optical axis of the objective lens on the basis of the result of discrimination, and condenses the light beam on the first recording layer or the second recording layer so as to carry out reproduction of information. turns on the first laser to emit light so that power exiting the objective lens is no more than the first power level; the discriminating means controls the laser driving means so that if the first amplitude is greater than the predetermined value the second laser emits light at no more than a second power level which is less than the first power level, and if the first amplitude is less than the predetermined value the second laser emits light at at least a third power level which is less than the second power level; and the discriminating means compares a second amplitude of reflected light obtained by the optical detector when the second laser is turned on with the first amplitude, to perform disk discrimination. 4. In a disk discrimination method for a recording and reproducing apparatus including a first laser emitting light with a first wavelength, a second laser emitting light with a wavelength less than the first wave length, and an objective lens focusing light emitted by the lasers onto a disk, the apparatus capable of recording information to a plurality of disk types requiring lasers with different wavelengths for recording operations, the discrimination method comprising the steps of: turning on the first laser so that power exiting the objective lens is no more than a first power level; determining if a first amplitude of a light reflected by the disk is less than a predetermined value, when the first laser is turned on to emit light so that power exiting the objective lens is no more than the first power level; turning on the second laser at no more than a second power level, which is less than the first power level, and obtaining a second amplitude of reflected light, if the first amplitude is greater than the predetermined value; turning on the second laser at at least a third power level, which is less than the second power level, and obtaining a second amplitude of reflected light, if the first amplitude is less than the predetermined value; and discriminating a type of the disk based on the first amplitude and the second amplitude.