Fast automatic gain control (AGC) for packet based systems

Patent metadata

Field	Value
Publication number	US-9490764-B2
Application number	US-201514689615-A
Country	US
Kind code	B2
Filing date	Apr 17, 2015
Priority date	Apr 17, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

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 sequence of a plurality of pre-defined power levels at a beginning of a preamble of the RF signal;
computing statistics for each of the plurality of pre-defined power levels at the beginning of the preamble of the RF signal; and
computing an appropriate gain for a variable gain amplifier (VGA) 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.

2. The method of claim 1 , wherein the RF signal further includes a data portion, the method 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 for each of the plurality of pre-defined power levels at the beginning of the preamble, until a start-of-packet (SoP) is detected.

5. The method of claim 4 , wherein the computing an 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) for use in a packet based wireless communication system, the WTRU comprising:
a receiver configured to receive a radio frequency (RF) signal including a sequence of a plurality of pre-defined power levels at a beginning of a preamble of the RF signal; and
an automatic gain control (AGC) circuit, wherein the AGC circuit is configured to compute statistics for each of the plurality of pre-defined power levels at the beginning of the preamble of the RF signal and compute an appropriate gain for a variable gain amplifier (VGA) 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.

9. The WTRU of claim 8 , wherein the RF signal includes a data portion, and wherein the AGC circuit is further 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 , further comprising:
a buffer configured to store the computed statistics for each of the plurality of pre-defined power levels at the beginning of the preamble, until a start-of-packet (SoP) is detected by the AGC circuit.

12. The WTRU of claim 11 , wherein the AGC circuit computes an appropriate gain for the VGA when the SoP is detected.

13. The WTRU of claim 8 , wherein the AGC circuit is further configured to store the computed appropriate gain for the VGA in a memory, wherein the stored computed appropriate gain is indexed by a corresponding link identifier in the memory and extract a previously computed appropriate gain for the VGA from the memory based on the corresponding link identifier to update a gain of the VGA.

Assignees

• Interdigital Patent Holdings Inc

Inventors

• Ferrante Steven
• Pietraski Philip J

Classifications

• H04B1/1027 Primary

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

• H03G3/3042 Primary

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