Variable PHY margin to combat ingress noise
View Patent ↗A method includes determining a first aggregate received power level of an orthogonal frequency division multiplexed (OFDM) signal received at a first network node, adjusting a nominal PHY Margin an amount that is dependent upon a measurement of an aggregate received power level of the OFDM signal, determining a data transmission rate based on the adjusted nominal PHY Margin, and receiving data being transmitted in accordance with the data transmission rate at the first node.
1. A method, comprising:
a) determining, by a first network node, a received power level of an Orthogonal Frequency Division Multiplexed (OFDM) signal received, over a channel, at the first network node;
b) adjusting a Physical Layer (PHY) Margin based on the received power level, wherein adjusting the PHY Margin comprises: determining whether the received power level is lower than at least one Subcarrier Added PHY Margin (SAPM) Threshold; c) if the received power level is lower than at least one SAPM Threshold, then determining a SAPM for at least one subcarrier based on a lowest SAPM Threshold that is greater than the received power level;
d) determining a signal to noise ratio (SNR) of the channel;
e) adding the determined SAPM to the SNR to determine an index value on a subcarrier by subcarrier basis; and
f) using the index value to determine a data transmission rate that is acceptable for communication of information over the channel to be used on a subcarrier by subcarrier basis.
2. The method of claim 1 , wherein adjusting the PHY Margin comprises:
a) determining whether the received power level is below an Additional Physical Layer Margin (APHYM) Threshold; and
b) adjusting the PHY Margin only if the received power level is below the APHYM Threshold.
3. The method of claim 1 , wherein determining the data transmission rate comprises:
a) determining a signal to noise ratio (SNR) of the received OFDM signal;
b) calculating an index value by adding or subtracting a predetermined amount to the SNR as indicated by the adjusted PHY Margin; and
c) using the index value as an index to determine the data transmission rate.
4. The method of claim 1 , wherein determining the data transmission rate comprises:
a) determining an SNR of the received OFDM signal;
b) using the SNR as an index to determine a data transmission rate; and
c) adjusting the data transmission rate an amount indicated by the adjusted PHY Margin.
5. The method of claim 4 , wherein there are a plurality of SAPM Thresholds, each SAPM Threshold associated with a subset of subcarriers and indicating a SAPM for each such subcarrier in the subset.
6. The method of claim 5 , wherein at least one subcarrier is associated with more than one SAPM Threshold and wherein the SAPM to be used to adjust the PHY Margin for that subcarrier is indicated by the SAPM Threshold that is higher than the received power level and that has the lowest value from among all other SAPM Thresholds associated with the same subcarrier.
7. The method of claim 1 , wherein determining the data transmission rate comprises:
a) determining a SNR for the received OFDM signal;
b) using the SNR as an index to determine a data transmission rate; and
c) communicating that the transmitter must transmit at the data transmission rate with higher power than was used to transmit the received OFDM signal, the amount of the power increase being determined by the adjusted PHY Margin.
8. The method of claim 1 , wherein determining the data transmission rate comprises:
a) determining the SNR for the received OFDM signal;
b) calculating an index value using the SNR based on the adjusted PHY Margin;
c) using the index value to determine the data transmission rate; and
d) communicating to a transmitting node the data transmission rate and also communicating to the transmitting node that the power level of the transmission at the data transmission rate should be above the power level used to transmit the received signal, the amount of the increase in power level being determined based on the adjusted PHY Margin.
9. The method of claim 1 , wherein amount of the adjustment to the PHY Margin is retrieved from a look-up table.
10. The method of claim 9 , wherein the look-up table includes a plurality of PHY Margin values, each of the plurality of PHY Margin values associated with a received power level.
11. The method of claim 1 , wherein the received power level is an aggregated receive power level (ARPL).
12. The method of claim 1 , wherein the received power level is a received signal strength indicator (RSSI).
13. The method of claim 1 , wherein the PHY Margin amount indicated by the SAPM for a first subcarrier is different than the PHY Margin amount indicated for a second subcarrier.
14. A network node, comprising:
a) a transceiver configured to receive an Orthogonal Frequency Division Multiplexed (OFDM) signal over a channel; and
b) a processor in a signal communication with the transceiver, the processor configured to:
i) determine a received power level of the received OFDM signal;
ii) adjust a Physical Layer (PHY) Margin based on the received power level, wherein adjusting the PHY Margin comprises: determining whether the received power level is lower than at least one Subcarrier Added PHY Margin (SAPM) Threshold; iii) if the received power level is lower than at least one SAPM Threshold, then determining a SAPM for at least one subcarrier based on a lowest SAPM Threshold that is greater than the received power level;
iv) determining a signal to noise ratio (SNR) of the channel; v) adding the determined SAPM to the SNR to determine an index value on a subcarrier by subcarrier basis; and
vi) using the index value to determine a data transmission rate that is acceptable for communication of information over the channel to be used on a subcarrier by subcarrier basis.
15. The network node of claim 14 , wherein the processor adjusts the PHY Margin by:
a) comparing the received power level with an Additional Physical Layer Margin (APHYM) Threshold;
b) if the received power level is greater than the APHYM Threshold, then adjusting the PHY Margin by an amount determined by using the received power as an index into an APHYM look up table (LUT).
16. The network node of claim 15 , wherein the processor determines the data transmission rate by:
a) determining a signal to noise ratio (SNR) of the channel;
b) adding the amount determined from the APHYM LUT to the SNR to determine an index value; and
c) using the index value as an index into an SNR/DATA TRANSMISSION RATE LUT to determine the data transmission rate.
17. The network node of claim 14 wherein using the index value to determine the data transmission rate comprises using the index value as an index into a SNR/DATA TRANSMISSION RATE LUT.
18. The network node of claim 14 , wherein the processor is configured to retrieve a value of the second PHY Margin from a look-up table that is in data communication with the processor.
19. The network node of claim 18 , wherein the look-up table includes a plurality of PHY Margin values, each of the plurality of PHY Margin values associated with an aggregate received power level.
20. The network node of claim 14 , wherein the data transmission rate is based on a quadrature amplitude modulation (QAM) scheme.
21. The network node of claim 14 , wherein the processor is configured to select a second PHY Margin value from a plurality of PHY Margin values stored in a memory device based on the second signal power level.
22. The network node of claim 21 , wherein the OFDM signal includes a plurality of subcarriers, and wherein the first and second PHY Margins are applied to each of the plurality of subcarriers of the OFDM signal.
23. The network node of claim 22 , wherein first PHY Margin is different from second PHY Margin.