Clear channel assessment procedure for 802.11n device

A technology of free channel assessment and equipment, which is applied in the direction of data exchange through path configuration, digital transmission system, electrical components, etc., and can solve the problems that the free channel assessment cannot be realized normally

Inactive Publication Date: 2009-12-02
BEIJING CEC HUADA ELECTRONIC DESIGN CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the signals on the two sideband channels are mixed together in the sampled 40MHz complex baseband signal, the original energy detection or carrier detection methods cannot normally realize the clear channel assessment (CCA) indication

Method used

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  • Clear channel assessment procedure for 802.11n device
  • Clear channel assessment procedure for 802.11n device
  • Clear channel assessment procedure for 802.11n device

Examples

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Embodiment Construction

[0018] Referring to the accompanying drawings, a specific implementation description of the idle channel assessment under the 40Mhz bandwidth is given below.

[0019] Among them, Hilbert transform is realized by Hilbert filter. The specific filter coefficients are as follows:

[0020] -7 0 -11 0 -24 0 -80 0 80 0 24 0 11 0 7

[0021] For the upper sideband detection, the sampled complex signal I(n)+j Q(n) is sampled as follows image 3 The processing steps shown. Since the 15th-order Hilbert filter will cause delay, the original signal is delayed by 7 beats, and the result of rotating the filter output by 90 degrees is synthesized into the analytical signal. For the analytical signal, calculate the energy square sum P of the adjacent 8-point complex baseband signal IQ (n), with the threshold P threshold Compare to determine whether the channel is idle. In the formula, n represents the current sampling moment, and n-i represents 0~7 sampling moments before the current samp...

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PUM

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Abstract

The invention discloses a method and a device for realizing clear channel assessment (CCA) when an 802.11n device works under the band width of 40MHz. The device is composed of two groups of independent detectors; in order to obtain CCA of the band width of 20MHz of an upper side band, the device inputs signals to a Hilbert transformer, and the output of the Hilbert transformer is combined with original signals to form analytic signals; analytic signals are performed with energy detection, or with carrier detection after down-conversion so as to obtain CCA of the band width of 20MHz of the upper side band; and for obtaining CCA of the band width of 20MHz of a lower side band, sampled signals are input into another group of identical detectors after taking conjugation.

Description

Technical field: [0001] The invention belongs to the field of wireless communication and relates to wireless local area network communication. Specifically, it relates to a clear channel assessment method for an 802.11n device working in a 40MHz bandwidth mode. Background technique: [0002] The Media Access Control (MAC) sublayer of the 802.11 series protocol adopts the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) mechanism as the medium access mechanism, and the RTS / CTS message switch is made as Secondary media access methods. [0003] The working process of the CSMA / CA protocol is: a WLAN station needs to transmit data in the wireless network. If it does not detect that data is being transmitted in the network, it will wait for a period of time, and then randomly select a time slot to continue detecting. If there is still no activity, the data is sent. If the station at the receiving end receives the complete data sent by the sending end, it will re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L29/06H04L12/28H04L12/26
Inventor 滕炜亮
Owner BEIJING CEC HUADA ELECTRONIC DESIGN CO LTD
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