Fast automatic gain control (AGC) for packet based systems

Patent metadata

Field	Value
Publication number	US-9742371-B2
Application number	US-201615290184-A
Country	US
Kind code	B2
Filing date	Oct 11, 2016
Priority date	Apr 17, 2014
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

A method and apparatus for use in a packet based wireless communication system for reducing automatic gain control (AGC) convergence time at a receiver are described. A radio frequency (RF) signal is received. The RF signal includes a sequence of a plurality of pre-defined power levels at a beginning of a preamble of the RF signal. Statistics for each of the plurality of pre-defined power levels at the beginning of the preamble of the RF signal are computed. An appropriate gain for a variable gain amplifier (VGA) is then computed based on the computed statistics for each of the plurality of pre-defined power levels and a-priori information related to transmission power differences between the plurality of pre-defined power levels of the sequence.

First claim

What is claimed is:

1. A method for use in a packet-based wireless communication system for reducing automatic gain control (AGC) convergence time at a receiver, the method comprising:
receiving a radio frequency (RF) signal including a preamble portion and a data portion;
applying a pre-defined sequence of gain levels at a variable gain amplifier (VGA) to the preamble portion of the RF signal;
computing statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the RF signal; and
computing an appropriate gain for the VGA based on the computed statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the RF signal.

2. The method of claim 1 , further comprising:
updating a gain of the VGA based on the computed appropriate gain to receive the data portion of the RF signal.

3. The method of claim 1 , wherein the packet based wireless communication system is an IEEE 802.11ad packet-based system.

4. The method of claim 1 , further comprising:
storing, in a buffer, the computed statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the received RF signal, until a start-of-packet (SoP) is detected.

5. The method of claim 4 , wherein computing the appropriate gain for the VGA is performed when the SoP is detected.

6. The method of claim 1 , further comprising:
storing the computed appropriate gain for the VGA in a memory, wherein the stored computed appropriate gain is indexed by a corresponding link identifier.

7. The method of claim 6 , further comprising:
extracting a previously computed appropriate gain for the VGA from the memory based on the corresponding link identifier; and
updating a gain of the VGA based on the extracted previously computed appropriate gain.

8. A wireless transmit/receive unit (WTRU) configured to operate in a packet-based wireless communication system by reducing automatic gain control (AGC) convergence time at a receiver in the WTRU, the WTRU comprising:
the receiver coupled to a baseband processor, a transmitter and an antenna;
the receiver configured to receive a radio frequency (RF) signal including a preamble portion and a data portion;
the receiver configured to apply a pre-defined sequence of gain levels at a variable gain amplifier (VGA) to the preamble portion of the RF signal;
the receiver configured to compute statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the RF signal; and
the receiver configured to compute an appropriate gain for the VGA based on the computed statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the RF signal.

9. The WTRU of claim 8 , wherein:
the receiver is configured to update a gain of the VGA based on the computed appropriate gain to receive the data portion of the RF signal.

10. The WTRU of claim 8 , wherein the packet based wireless communication system is an IEEE 802.11ad packet-based system.

11. The WTRU of claim 8 , wherein:
the receiver is further configured to store, in a buffer, the computed statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the received RF signal, until a start-of-packet (SoP) is detected.

12. The WTRU of claim 11 , wherein:
the receiver is configured to compute the appropriate gain for the VGA is performed when the SoP is detected.

13. The WTRU of claim 8 , wherein:
the receiver is further configured to store the computed appropriate gain for the VGA in a memory, wherein the stored computed appropriate gain for the VGA is indexed by a corresponding link identifier.

14. The WTRU of claim 13 , wherein:
the receiver is configured to extract a previously computed appropriate gain for the VGA from the memory based on the corresponding link identifier; and
the receiver is configured to update a gain of the VGA based on the extracted previously computed appropriate gain.

15. A method for use in a packet-based wireless communication system for reducing automatic gain control (AGC) convergence time at a receiver, the method comprising:
receiving a packet in a wireless radio frequency (RF) signal, wherein the packet includes a preamble portion and a data portion;
applying a pre-defined sequence of gain levels at a variable gain amplifier (VGA) to the preamble portion;
computing statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the RF signal, wherein the statistics correspond to one or more of a signal power, a signal amplitude, a signal root mean square (RMS) value, and a peak-to-peak signal amplitude;
computing an appropriate gain for the VGA based on the computed statistics when each of the pre-defined sequence of gain levels is applied to the preamble portion of the RF signal; and
amplifying, by the VGA, the data portion of the packet, based on the computed appropriate gain.

16. The method of claim 15 , wherein the packet based wireless communication system is a cellular based wireless communication system.

17. The method of claim 15 , wherein the packet is received from a base station.

Assignees

• Interdigital Patent Holdings Inc

Inventors

• Ferrante Steven
• Pietraski Philip J

Classifications

• H03G3/3042

  in modulators, frequency-changers, transmitters or power amplifiers · CPC title

• H04B1/1027 Primary

  assessing signal quality or detecting noise/interference for the received signal · CPC title

• H03G3/3078

  Circuits generating control signals for digitally modulated signals · CPC title

• H03G3/20 Primary

  Automatic control ({H03G3/005 takes precedence;} combined with volume compression or expansion H03G7/00) · CPC title