Enhanced Wideband High Frequency (HF) data transmission with adaptive interference avoidance
Methods, devices, and system for Enhanced Wideband HF data transmission with adaptive interference avoidance and other improvements. Several embodiments describe a mesh network comprising a plurality of transmitting and receiving nodes in a congested band. The network senses the interference spectrum occupancies at a plurality of receiver nodes and synthesizes transmit waveforms at the transmit nodes so that the spectra of the transmit signals fit into the gaps of the interference spectra at the receiver nodes. The waveform is based on FDM, including OFDM, with adaptive tone suppression at the transmitter. The spectrum occupancy information at each node is continually shared in the background among all nodes using a low data rate, Fountain code with erasure sensing at the receivers, which guarantees robust delivery.
1 . A method of communicating data packets through a wireless communication network, comprising:
receiving, by a transceiver device from a receiver device, spectrum occupancy attributes of narrowband interference on a communication channel at a location of the receiver device; and
transmitting, from the transceiver device to the receiver device, a data packet using a waveform having a spectrum occupancy that is based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the receiver device.
2 . The method of claim 1 , wherein transmitting the data packet using the waveform generated based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the receiver device comprises:
transmitting the data packet using a frequency division multiplexed waveform comprising a plurality of subcarriers and suppressing at least some of the subcarriers from transmission based on the spectrum occupancy attributes of the narrowband interference on the communication channel; and
assigning user data to be carried only by the transmitted subcarriers.
3 . The method of claim 2 , wherein transmitting the data packet using the frequency division multiplexed waveform comprising the plurality of subcarriers comprises:
transmitting the data packet using a frequency division multiplexed waveform that includes a plurality of mutually orthogonal subcarriers, wherein each of the mutually orthogonal subcarriers is modulated with a subset of the data contained in one transmit interleaving block.
4 . The method of claim 2 , further comprising applying power saved by suppressing the subcarriers towards transmitting the subcarriers that have not been suppressed.
5 . The method of claim 1 , wherein transmitting the data packet using the waveform generated based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the receiver device comprises:
selecting a modulation and coding scheme for each transmitted subcarrier based on an interference power within spectrum occupied by the subcarrier at the receiver device.
6 . The method of claim 1 , wherein transmitting the data packet using the waveform generated based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the receiver device comprises:
generating the waveform based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the transceiver device.
7 . The method of claim 1 , further comprising:
determining, by the transceiver device, spectrum occupancy attributes of narrowband interference on the communication channel at the location of the transceiver device; and
broadcasting, by the transceiver device, the determined spectrum occupancy attributes for reception by one or more other devices.
8 . The method of claim 7 , wherein determining the spectrum occupancy attributes of the narrowband interference on the communication channel comprises:
sensing a power spectral density of the narrowband interference during a period of radio silence; and
generating a spectrum usability mask from the sensed power spectral density.
9 . The method of claim 7 , wherein determining the spectrum occupancy attributes of narrowband interference on the communication channel at the location of the receiver device comprises:
computing a power spectral density of the waveform:
based on a discrete Fourier transform, or
based on a fast Fourier transform; and
generating a spectrum usability mask by quantizing the power spectral density relative to a set of threshold values.
10 . The method of claim 9 , wherein generating the spectrum usability mask by quantizing the power spectral density relative to the set of threshold values comprises:
identifying a threshold level of interference power received by a known subcarrier that is not exceeded when averaged over a known period of time.
11 . The method of claim 9 , wherein generating the spectrum usability mask by quantizing the power spectral density relative to the set of threshold values comprises:
identifying upper and lower threshold limits of interference power received by a known subcarrier such that, when the interference power is averaged over a known period of time, a value of the average interference power is bounded by the upper and lower threshold limits.
12 . The method of claim 7 , further comprising:
generating a demodulated data set by demodulating modulated data carried by subcarriers in the waveform; and
erasing data carried by the subcarriers of the waveform that include cochannel interference.
13 . The method of claim 7 , further comprising:
generating a demodulated data set by demodulating modulated data carried by subcarriers in the waveform;
determining whether the demodulated data set includes a demodulated data packet that includes an uncorrected error; and
erasing the demodulated data packet in response to determining that the demodulated data set includes the demodulated data packet that includes the uncorrected error.
14 . The method of claim 7 , further comprising:
identifying packets that are free of errors;
maintaining a first count of the number of packets received in the receiver device; and
maintaining a second count of the number of packets received error free in the receiver device.
15 . The method of claim 7 , wherein the communication channel comprises a plurality of discontiguous subchannels in the radio spectrum, the subchannels having arbitrary bandwidths, the method further comprising:
aggregating, by a transceiver device, the plurality of discontiguous subchannels to form a contiguous channel at an intermediate frequency.
16 . The method of claim 15 , wherein:
the intermediate frequency in the transceiver device is zero Hz; and
the signals are represented in the transceiver device in complex baseband form.
17 . A transceiver device, comprising:
a processor configured to:
receive, from a receiver device, spectrum occupancy attributes of narrowband interference on a communication channel at a location of the receiver device; and
transmit, to the receiver device, a data packet using a waveform having a spectrum occupancy that is based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the receiver device.
18 . The transceiver device of claim 17 , wherein the processor is configured to transmit the data packet using the waveform generated based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the receiver device by:
transmitting the data packet using a frequency division multiplexed waveform comprising a plurality of subcarriers and suppressing at least some of the subcarriers from transmission based on the spectrum occupancy attributes of the narrowband interference on the communication channel; and
assigning user data to be carried only by the transmitted subcarriers.
19 . The transceiver device of claim 18 , wherein the processor is configured to transmit the data packet using the frequency division multiplexed waveform comprising the plurality of subcarriers by:
transmitting the data packet using a frequency division multiplexed waveform comprising a plurality of mutually orthogonal subcarriers, wherein each of the mutually orthogonal subcarriers is modulated with a subset of the data contained in one transmit interleaving block.
20 . The transceiver device of claim 18 , wherein the processor is further configured to apply power saved by suppressing the subcarriers towards transmitting the subcarriers that have not been suppressed.
21 . The transceiver device of claim 17 , wherein the processor is further configured to:
select a modulation and coding scheme for each transmitted subcarrier based on an interference power within spectrum occupied by the subcarrier at the receiver device.
22 . The transceiver device of claim 17 , wherein the processor is further configured to:
generate the waveform based on the spectrum occupancy attributes of the narrowband interference on the communication channel at the location of the transceiver device.
23 . The transceiver device of claim 17 , wherein the processor is further configured to:
determine the spectrum occupancy attributes of narrowband interference on the communication channel at the location of the transceiver device; and
broadcast the determined spectrum occupancy attributes for reception by one or more other devices.
24 . The transceiver device of claim 23 , wherein the processor is configured to determine the spectrum occupancy attributes of the narrowband interference on the communication channel by performing operations that include:
sensing a power spectral density of the narrowband interference during a period of radio silence; and
generating a spectrum usability mask from the sensed power spectral density.
25 . The transceiver device of claim 23 , wherein the processor is configured to determine the spectrum occupancy attributes of the narrowband interference on the communication channel by performing operations that include:
computing a power spectral density of the waveform:
based on a discrete Fourier transform, or
based on a fast Fourier transform; and
generating a spectrum usability mask by quantizing the power spectral density relative to a set of threshold values.
26 . The transceiver device of claim 25 , wherein the processor is configured to generate the spectrum usability mask by quantizing the power spectral density relative to the set of threshold values by performing operations that include:
identifying a threshold level of interference power received by a known subcarrier that is not exceeded when averaged over a known period of time.
27 . The transceiver device of claim 25 , wherein the processor is configured to generate the spectrum usability mask by quantizing the power spectral density relative to the set of threshold values by performing operations that include:
identifying upper and lower threshold limits of interference power received by a known subcarrier such that, when the interference power is averaged over a known period of time, a value of the average interference power is bounded by the upper and lower threshold limits.
28 . The transceiver device of claim 23 , wherein the processor is further configured to:
generate a demodulated data set by demodulating modulated data carried by subcarriers in the waveform; and
erase data carried by the subcarriers of the waveform that include cochannel interference.
29 . The transceiver device of claim 23 , wherein the processor is further configured to:
generate a demodulated data set by demodulating modulated data carried by subcarriers in the waveform;
determine whether the demodulated data set includes a demodulated data packet that includes an uncorrected error; and
erase the demodulated data packet in response to determining that the demodulated data set includes the demodulated data packet that includes the uncorrected error.
30 . The transceiver device of claim 23 , wherein the processor is further configured to:
identify packets that are free of errors;
maintain a first count of the number of packets received in the receiver device; and
maintain a second count of the number of packets received error free in the receiver device.
31 . The transceiver device of claim 23 , wherein:
the communication channel comprises a plurality of discontiguous subchannels in the radio spectrum, the subchannels having arbitrary bandwidths; and
the transceiver device is configured to aggregate the plurality of discontiguous subchannels to form a contiguous channel at an intermediate frequency.
32 . The transceiver device of claim 31 , wherein:
the intermediate frequency is zero Hz; and
the processed signals are represented in complex baseband form.