Abstract: Provided is a wireless communication system in which, based on a random access scheme, a transmission opportunity (TXOP) acquired by a wireless access point is granted to a wireless station when performing uplink data transmission from the wireless station to the wireless access point and the TXOP acquired by the wireless station is granted to the wireless access point when performing downlink data transmission from the wireless access point to the wireless station, the system includes a scheduling unit for TXOP granting determining one or more wireless stations having a quality of an uplink data transmission lower than a prescribed value as TXOP responders to which the wireless access point grants the TXOP, and determining one or more wireless stations having a quality of a downlink data transmission lower than the prescribed value as TXOP holders which grant the TXOP to the wireless access point.

Abstract: This process for the desulfurization and denitration of light oil is effected by extraction with an organic solvent containing nitrogen. The invention also relates to light oil desulfurized and denitrated by said process as well as an organic solvent containing nitrogen for the extraction. The solvent is selected from among, for example, hetrocyclic compounds containing nitrogen, such as pyrrolidones, imidazolidinones, pyrimidinones and pyridinium salts, and acid amides. The combination of the process of this invention with any ordinary process for hydrodesulfurization enables the production of light oil having a sulfur content not exceeding 0.01% by weight. Light oil still containing benzothiophenone and dibenzothiophenone derivatives after hydrodesulfurization can be easily desulfurized to yield a desulfurized product not having any undesirable color, or any offensive smell. Also, the extraction of nitrogen compounds and aromatic compound from light oil is effected by the same process.