RFID decoding subsystem with pre-decode module

• US 7,734,994 B2
• Filed: 07/20/2006
• Issued: 06/08/2010
• Est. Priority Date: 07/20/2006
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Rofougaran, Ahmadreza (Reza), Shoarinejad, Kambiz
• Primary Examiner(s): Baker; Stephen M
• Application Number:
  US11/490,968
• Publication Number:
  US 20080065957A1
• Time in Patent Office: 1,419 Days
• Field of Search: 714/807, 370/346
• US Class Current: 714/807
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

A radio frequency identification (RFID) decoding subsystem includes a pre-decode module and a decode module. The pre-decode module is coupled to process down-converted RFID signals into at least one of pre-decoded baseband data and corresponding decoding information. The decode module is coupled to process the pre-decoded baseband data into decoded RFID data, where the processing of the pre-decoded baseband data is based on the corresponding decoding information when the corresponding decoding information is produced by the pre-decoder module.

Claims

1. A radio frequency identification (RFID) decoding subsystem comprises:

pre-decode module coupled to process down-converted RFID signals into pre-decoded baseband data and corresponding decoding information, wherein the pre-decoded baseband data includes limited in-phase component signals of the down-converted RFID signals and limited quadrature component signals of the down-converted RFID signals, and wherein the corresponding decoding information includes signal strength of filtered quadrature components and signal strength of filtered in-phase components; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data, wherein the processing of the pre-decoded baseband data is based on the corresponding decoding information, wherein the decode module processes the pre-decoded baseband data by;

decoding the limited in-phase component signals to produce decoded in-phase RFID data;

decoding the limited quadrature component signals to produce decoded quadrature RFID data; and

selecting the decoded in-phase RFID data or the decoded quadrature RFID data as the decoded RFID data based on the least one of the signal strength of the filtered quadrature components and the signal strength of the filtered in-phase components.

2. The RFID decoding subsystem of claim 1, wherein the pre-decode module comprises:

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce the filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce the filtered quadrature component signals;

an in-phase received signal strength indication (RSSI) module coupled to determine the signal strength of the filtered in-phase components;

a quadrature RSSI module coupled to determine the signal strength of the filtered quadrature components;

an in-phase limiting module coupled to limit the filtered in-phase component signals to produce the limited in-phase component signals;

a quadrature limiting module coupled to limit the filtered quadrature component signals to produce the limited quadrature component signals.

3. The RFID decoding subsystem of claim 1, wherein the pre-decode module comprises:

a digital down converter to down convert to intermediate frequency RFID signals into baseband RFID signals, wherein the baseband RFID signals corresponds to the down-converted RFID signals.

4. A radio frequency identification (RFID) decoding subsystem comprises:

pre-decode module coupled to process down-converted RFID signals into pre-decoded baseband data, wherein the pre-decode module comprises;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

amplitude estimation module coupled to estimate amplitude of the down-converted RFID signals based on the filtered in-phase and quadrature component signals to produce an estimated amplitude; and

a limiting module coupled to produce the pre-decoded baseband data based on the estimated amplitude; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data.

5. The RFID decoding subsystem of claim 4, wherein the amplitude estimation module performs at least one of:

√

{square root over (I²+Q²)}, wherein I represents amplitude of the in-phase component signals and Q represents amplitude of the quadrature component signals; and

max(|I|,|Q|)+0.5*min(|I|,|Q|).

6. A radio frequency identification (RFID) decoding subsystem comprises:

pre-decode module coupled to process down-converted RFID signals into at least one of pre-decoded baseband data and corresponding decoding information, wherein the pre-decode module comprises;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

an in-phase received signal strength indication (RSSI) module coupled to determine signal strength of the filtered in-phase components;

a quadrature RSSI module coupled to determine signal strength of the filtered quadrature components;

an in-phase limiting module coupled to limit the filtered in-phase component signals to produce limited in-phase component signals;

a quadrature limiting module coupled to limit the filtered quadrature component signals to produce limited quadrature component signals; and

selection module coupled to select the limited in-phase quadrature component signals or the limited quadrature component signals as the pre-decoded baseband data based on at least one of the signal strength of the filtered in-phase components and the signal strength of the filtered quadrature components; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data.

7. A radio frequency identification (RFID) decoding subsystem comprises:

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

an in-phase received signal strength indication (RSSI) module coupled to produce an in-phase weighting factor in accordance with signal strength of the filtered in-phase components;

a quadrature RSSI module coupled to produce a quadrature weighting factor in accordance with signal strength of the filtered quadrature components;

an in-phase limiting module coupled to limit the filtered in-phase component signals to produce limited in-phase component signals;

a quadrature limiting module coupled to limit the filtered quadrature component signals to produce limited quadrature component signals;

an in-phase counting module coupled to count transitions of the limited in-phase component signals to produce an in-phase count;

a quadrature counting module coupled count transitions of the limited quadrature component signals to produce a quadrature count;

a weighting module coupled to weight the in-phase count based on the in-phase weighting factor to produce a weighted in-phase count and to weight the quadrature count based on the quadrature weighting factor to produce a weighted quadrature count; and

a decision module coupled to produce the decoded baseband data in response to the weighted in-phase count and the weighted quadrature count.

8. A radio frequency identification (RFID) decoding subsystem comprises:

decode module coupled to process pre-decoded baseband data into decoded RFID data; and

pre-decode module coupled to process down-converted RFID signals into the pre-decoded baseband data, wherein the pre-decode module comprises;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

multiplexer coupled to provide the filtered in-phase component signals as the pre-decoded baseband data when a selection signal is in a first state and to provide the filtered quadrature component signals as the pre-decoded baseband data when the selection signal is in a second state, wherein one of the first and second states of the selection signal corresponds to an errorless cyclic redundancy check (CRC) of the decoded RFID data and another of the first and second states of the select signal corresponds to an error of the CRC of the decoded RFID data.

9. A radio frequency identification (RFID) decoding subsystem comprises:

pre-decode module coupled to process down-converted RFID signals into pre-decoded baseband data, wherein the pre-decode module comprises;

a processing module coupled to process the down-converted RFID signals into at least one of pre-decoded baseband data and corresponding decoding information in accordance with one of a plurality of pre-decoding processes, wherein the one of the plurality of pre-decoding processes is selected in accordance with a pre-decoding selection signal, wherein the processing module further functions to interpret at least one of a preamble of the down-converted RFID signals or system setup information to establish a state for the pre-decoding selection signal; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data, wherein the processing of the pre-decoded baseband data is based on the corresponding decoding information when the corresponding decoding information is produced by the pre-decoder module.

10. A radio frequency identification (RFID) reader receiver comprises:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;

a block cancellation module coupled to receive an outbound RF signal from an RFID transmitter and to substantially cancel a blocking signal from the amplified inbound RF signal using the outbound RF signal and substantially pass a modulated RF signal;

a down-conversion module coupled to convert the modulated RF signal to down-converted RFID signals;

pre-decode module coupled to process down-converted RFID signals into pre-decoded baseband data and corresponding decoding information, wherein the pre-decoded baseband data includes limited in-phase component signals of the down-converted RFID signals and limited quadrature component signals of the down-converted RFID signals, and wherein the corresponding decoding information includes signal strength of filtered quadrature components and signal strength of filtered in-phase components; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data, wherein the processing of the pre-decoded baseband data is based on the corresponding decoding information, wherein the decode module processes the pre-decoded baseband data by;

decoding the limited in-phase component signals to produce decoded in-phase RFID data;

decoding the limited quadrature component signals to produce decoded quadrature RFID data; and

selecting the decoded in-phase RFID data or the decoded quadrature RFID data as the decoded RFID data based on the least one of the signal strength of the filtered quadrature components and the signal strength of the filtered in-phase components.

11. The RFID reader receiver of claim 10, wherein the pre-decode module comprises:

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce the filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce the filtered quadrature component signals;

an in-phase received signal strength indication (RSSI) module coupled to determine the signal strength of the filtered in-phase components;

a quadrature RSSI module coupled to determine the signal strength of the filtered quadrature components;

an in-phase limiting module coupled to limit the filtered in-phase component signals to produce the limited in-phase component signals;

a quadrature limiting module coupled to limit the filtered quadrature component signals to produce the limited quadrature component signals.

12. The RFID reader receiver of claim 10, wherein the pre-decode module comprises:

a digital down converter to down convert to intermediate frequency RFID signals into baseband RFID signals, wherein the baseband RFID signals corresponds to the down-converted RFID signals.

13. A radio frequency identification (RFID) reader receiver comprises:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;

a block cancellation module coupled to receive an outbound RF signal from an RFID transmitter and to substantially cancel a blocking signal from the amplified inbound RF signal using the outbound RF signal and substantially pass a modulated RF signal;

a down-conversion module coupled to convert the modulated RF signal to down-converted RFID signals;

pre-decode module coupled to process down-converted RFID signals into pre-decoded baseband data, wherein the pre-decode module comprises;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

amplitude estimation module coupled to estimate amplitude of the down-converted RFID signals based on the filtered in-phase and quadrature component signals to produce an estimated amplitude; and

a limiting module coupled to produce the pre-decoded baseband data based on the estimated amplitude; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data.

14. The RFID reader receiver of claim 13, wherein the amplitude estimation module performs at least one of:

√

{square root over (I²+Q²)}, wherein I represents amplitude of the in-phase component signals and Q represents amplitude of the quadrature component signals; and

max(|I|,|Q|)+0.5*min(|I|,|Q|).

15. A radio frequency identification (RFID) reader receiver comprises:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;

a block cancellation module coupled to receive an outbound RF signal from an RFID transmitter and to substantially cancel a blocking signal from the amplified inbound RF signal using the outbound RF signal and substantially pass a modulated RF signal;

a down-conversion module coupled to convert the modulated RF signal to down-converted RFID signals;

pre-decode module coupled to process down-converted RFID signals into at least one of pre-decoded baseband data and corresponding decoding information, wherein the pre-decode module comprises;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

an in-phase received signal strength indication (RSSI) module coupled to determine signal strength of the filtered in-phase components;

a quadrature RSSI module coupled to determined signal strength of the filtered quadrature components;

an in-phase limiting module coupled to limit the filtered in-phase component signals to produce limited in-phase component signals;

a quadrature limiting module coupled to limit the filtered quadrature component signals to produce limited quadrature component signals; and

selection module coupled to select the limited in-phase quadrature component signals or the limited quadrature component signals as the pre-decoded baseband data based on at least one of the signal strength of the filtered in-phase components and the signal strength of the filtered quadrature components; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data.

16. A radio frequency identification (RFID) reader receiver comprises:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;

a block cancellation module coupled to receive an outbound RF signal from an RFID transmitter and to substantially cancel a blocking signal from the amplified inbound RF signal using the outbound RF signal and substantially pass a modulated RF signal;

a down-conversion module coupled to convert the modulated RF signal to down-converted RFID signals;

a decoding subsystem that includes;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

an in-phase received signal strength indication (RSSI) module coupled to produce an in-phase weighting factor in accordance with signal strength of the filtered in-phase components;

a quadrature RSSI module coupled to produce a quadrature weighting factor in accordance with signal strength of the filtered quadrature components;

an in-phase limiting module coupled to limit the filtered in-phase component signals to produce limited in-phase component signals;

a quadrature limiting module coupled to limit the filtered quadrature component signals to produce limited quadrature component signals;

an in-phase counting module coupled count transitions of the limited in-phase component signals to produce an in-phase count;

a quadrature counting module coupled count transitions of the limited quadrature component signals to produce a quadrature count; and

a weighting module coupled to weight the in-phase count based on the in-phase weighting factor to produce a weighted in-phase count and to weight the quadrature count based on the quadrature weighting factor to produce a weighted quadrature count; and

a decision module coupled to produce the decoded baseband data in response to the weighted in-phase count and the weighted quadrature count.

17. A radio frequency identification (RFID) reader receiver comprises:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;

a block cancellation module coupled to receive an outbound RF signal from an RFID transmitter and to substantially cancel a blocking signal from the amplified inbound RF signal using the outbound RF signal and substantially pass a modulated RF signal;

a down-conversion module coupled to convert the modulated RF signal to down-converted RFID signals;

decode module coupled to process pre-decoded baseband data into decoded RFID data; and

pre-decode module coupled to process down-converted RFID signals into the pre-decoded baseband data, wherein the pre-decode module comprises;

an in-phase filter coupled to filter in-phase components of the down-converted RFID signals to produce filtered in-phase component signals;

a quadrature filter coupled to filter quadrature components of the down-converted RFID signals to produce filtered quadrature component signals;

multiplexer coupled to provide the filtered in-phase component signals as the pre-decoded baseband data when a selection signal is in a first state and to provide the filtered quadrature component signals as the pre-decoded baseband data when the selection signal is in a second state, wherein one of the first and second states of the selection signal corresponds to an errorless cyclic redundancy check (CRC) of the decoded RFID data and another of the first and second states of the select signal corresponds to an error of the CRC of the decoded RFID data.

18. A radio frequency identification (RFID) reader receiver comprises:

a low noise amplifier coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;

a block cancellation module coupled to receive an outbound RF signal from an RFID transmitter and to substantially cancel a blocking signal from the amplified inbound RF signal using the outbound RF signal and substantially pass a modulated RF signal;

a down-conversion module coupled to convert the modulated RF signal to down-converted RFID signals;

decode module coupled to process pre-decoded baseband data into decoded RFID data; and

pre-decode module coupled to process down-converted RFID signals into the pre-decoded baseband data, wherein the pre-decode module comprises;

a processing module coupled to process the down-converted RFID signals into at least one of pre-decoded baseband data and corresponding decoding information in accordance with one of a plurality of pre-decoding processes, wherein the one of the plurality of pre-decoding processes is selected in accordance with a pre-decoding selection signal, wherein the processing module further functions to interpret at least one of a preamble of the down-converted RFID signals or system setup information to establish a state for the pre-decoding selection signal; and

decode module coupled to process the pre-decoded baseband data into decoded RFID data, wherein the processing of the pre-decoded baseband data is based on the corresponding decoding information when the corresponding decoding information is produced by the pre-decoder module.