Method, system to achieve fast active scan in WLAN, access point and mobile station

Abstract

A method for fast active scanning and an Access Point apparatus that reduces the delay in convention active scanning. The method includes the step of giving an AP higher priority to transmit a probe response than is currently known. This priority comes at the delay of transmission of the probe response, so preferably the probe response can be delayed by just the time that the AP needs to prepare the response plus the time, if any, for the frame already in the air to finish. According to the invention, a method can include steps for: sending a uni-cast probe request message by an (STA) 238, 248, 268 on a particular channel having at least one Access Point (AP) 258, 278 in communication therewith; receiving by one particular (AP) 278 the probe request message sent by the (STA); sensing by the particular (AP) 278 of a point coordination function (PCF) interframe space (PIFS) 325 of the particular channel; and sending by the particular (AP) 278 of a probe response message to the (STA) 238in response to the probe request message after the PIFS. As the probe request is uni-cast, there is no need for a backoff interval as only one AP will respond. Since normal traffic utilizes the longer DIFS space plus backoffs to avoid collisions, the AP will always be able to respond to a probe request of scan faster than other items can respond on the channel, thus giving the AP priority when sending the probe response message.

Description

technical field [0001] The present invention relates to wireless local area networks using the IEEE 802.11 protocol. More particularly, the invention relates to the process that occurs when a device is handed over from a first Access Point until a new link is established at a second Access Point. Background technique [0002] 802.11 WLAN supports two types of networks, Infrastructure Basic Service Set (BSS) and Independent Basic Service Set (IBSS). A BSS is a basic building block of a WLAN and can be defined as a collection of stations that communicate with each other, typically through the coordination of access points (APs). According to this, each BSS is composed of at least two stations (STA) and an access point (AP). [0003] The operation mode for BSS is called infrastructure mode, in which there is at least one AP and one STA, and the supported AP and one or more STAs are called Basic Service Set (Basic Service Set). STAs use APs to access resources of the wired ne...

AI Technical Summary

Problems solved by technology

[0019] In conclusion, scanning according to the form given above has disadvantages, whether it is active or passive

Even with active scanning, the channel scanning process can take hundreds of milliseconds in the worst scenario, where the STA has to scan all possible channels

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