Method and device for detecting preamble of wireless data frame

• US 7,218,628 B2
• Filed: 07/29/2002
• Issued: 05/15/2007
• Est. Priority Date: 02/07/2002
• Status: Expired due to Fees

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Lin, Chu-Ming, Chen, Po-Hung, Chiu, Mao-Ching, Lin, Chin-Wen, Cheng, Tai-Yuan
• Primary Examiner(s): Chan; Wing
• Assistant Examiner(s): LEE, ANDREW CHUNG CHEUNG
• Application Number:
  US10/209,489
• Publication Number:
  US 20030147374A1
• Time in Patent Office: 1,751 Days
• Field of Search: 370/329, 370/342, 370/338, 370/349
• US Class Current: 370/349
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15
• CPC Class Codes: H04W 99/00 Subject matter not provided for in other groups of this subclass

Abstract

A method and a device for detecting a preamble type of a wireless data frame are provided. The preamble has a synchronization (SYNC) field and a start frame delimiter (SFD) field, and the method comprises following steps. The wireless data frame is first received, and then determined whether the wireless data frame has a short preamble. When the wireless data frame has the short preamble, the wireless data frame is transmitted to a MAC device. In addition, if the wireless data frame does not have the short preamble, it determines whether the wireless data frame has a long preamble. When the wireless data frame has the long preamble, the wireless data frame is then transmitted to the MAC device.

Claims

1. A method for detecting a preamble type of a wireless data frame, wherein the preamble has a synchronization (SYNC) field and a start frame delimiter (SFD) field, the method comprising steps of:

receiving the wireless data frame;

determining whether the wireless data frame has a short preamble by checking a pattern of the SFD according to a length of the SYNC field of the received wireless data frame;

transmitting the wireless data frame to a MAC device when the wireless data frame has the short preamble;

determining whether the wireless data frame has a long preamble if the wireless data frame does not have the short preamble; and

,

transmitting the wireless data frame to the MAC device when the wireless data frame has the long preamble.

2. The method of claim 1, wherein the step for determining whether the wireless data frame has the short preamble further comprises steps of:

counting to a bit number of the SYNC field for the short type preamble; and

checking whether the SFD field complies with a specified pattern for the short preamble.

3. The method of claim 2, wherein the step for determining whether the wireless data frame has the long preamble further comprises steps of:

keeping counting to a bit number of the SYNC field for the long type preamble; and

checking whether the SFD field complies with a specified pattern for the long preamble.

4. The method of claim 1, further comprising steps of:

discarding the received data frame if the received data frame has neither the short type nor the long type preamble; and

turning to a mode listening to a new-coming wireless data frame.

5. A method for detecting a preamble type of a wireless data frame, wherein the preamble has a synchronization (SYNC) field and a start frame delimiter (SFD field the method comprising steps of:

receiving the wireless data frame;

presuming that the received wireless data frame has a short type preamble;

determining whether the wireless data frame has the short preamble by checking a pattern of the SFD according to a length of the SYNC field of the received wireless data frame;

transmitting the wireless data frame to a MAC device when the wireless data frame has the short preamble;

presuming that the received wireless data frame has a long type preamble if the wireless data frame does not have the short preamble;

determining whether the wireless data frame has the long preamble; and

transmitting the wireless data frame to the MAC device when the wireless data frame has the long preamble.

6. The method of claim 5, wherein the step for determining whether the wireless data frame has the short preamble further comprises steps of:

counting to a bit number of the SYNC field for the short type preamble; and

checking whether the SFD field complies with a specified pattern for the short preamble.

7. The method of claim 6, wherein the step for determining whether the wireless data frame has the long preamble further comprises steps of:

keeping counting to a bit number of the SYNC field for the long type preamble; and

checking whether the SFD field complies with a specified pattern for the long preamble.

8. The method of claim 5, further comprising steps of:

discarding the received data frame if the received data frame has neither the short type nor the long type preamble; and

turning to a mode listening to a new-coming wireless data frame.

9. A device capable of detecting a preamble type of a wireless data frame, wherein the preamble has a synchronization (SYNC) field and a start frame delimiter (SFD) field the device comprising:

a MAC (media access control) device;

a receiver for receiving the wireless data frame;

a demodulator/decoder module coupled to the receiver;

a descrambler coupled to the demodulator/decoder module;

a switching device coupled between the MAC device and the descrambler; and

a preamble detector, coupled to the descrambler and the switching device, wherein the preamble detector outputs a control signal to the switching device for establishing a connection between the descrambler and the MAC device when the received wireless data frame has a short type preamble or a long type preamble, wherein the short or the long type preamble is determined according to a length of the SYNC field of the received wireless data frame and then checking a pattern of the SFD.

10. The device of claim 9, wherein the preamble detector further comprises a counter for counting bits of the received wireless data frame.