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Clear channel assessment method for 802.11n equipment

A technology of free channel assessment and equipment, which is applied in data exchange through path configuration, digital transmission system, electrical components, etc., and can solve problems such as the inability to normally realize free channel assessment

Inactive Publication Date: 2011-12-07
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 method for 802.11n equipment
  • Clear channel assessment method for 802.11n equipment
  • Clear channel assessment method for 802.11n equipment

Examples

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Embodiment Construction

[0019] Referring to the accompanying drawings, a specific implementation description of the idle channel evaluation under the bandwidth of 40Mhz is given.

[0020] The Hilbert transform is implemented by using the Hilbert filter. The coefficients of the specific filter are as follows:

[0021] -7 0 -11 0 -24 0 -80 0 80 0 24 0 11 0 7

[0022] For upper sideband detection, the sampled complex signal I(n)+j·Q(n) is sampled and performed as follows image 3 processing steps shown. Since passing through the 15th-order Hilbert filter will generate a delay, after delaying the original signal by 7 beats, it is combined with the result of rotating the filter output by 90 degrees to synthesize the analytical signal. For analytical signals, calculate the sum of squared energy P of adjacent 8-point complex baseband signals IQ (n), with the threshold P threshold Compare and judge whether the channel is idle. In the formula, n represents the current sampling time, and n-i represents t...

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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 802.11n equipment works in a bandwidth of 40MHz. The device is composed of two independent detection devices. In order to obtain an idle channel assessment with an upper sideband of 20MHz bandwidth, the device inputs the signal into a Hilbert transformer, and synthesizes the output of the transformer with the original signal to analyze the signal. Perform energy detection or carrier detection after down-converting the analysis signal to obtain an idle channel evaluation with an upper sideband of 20Mhz bandwidth. In order to obtain the idle channel evaluation of the lower sideband 20MHz bandwidth, the sampled signal is conjugated and then input to another group of the same detection device.

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 method for clear channel assessment (Clear Channel Assessment) of an 802.11n device operating 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 is made by the RTS / CTS message switch. Assisted media access. [0003] The workflow 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 slice to continue the detection. If there is still no activity, the data is sent. If the receiving station receives the complete data sent by the sender, it ...

Claims

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Application Information

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