Characterizing channel response in a single upstream burst using redundant information from training tones
Characterizing channel response in a single upstream burst using redundant information from training tones (TTs). The invention is operable to utilize inserted TTs, contained within a transmitted data frame, to provide for an improved estimate of a communication channel's actual response and an improved estimate of the noise of the communication channel. The invention determines a maximum allowable delay spread of the many communication paths within a multi-path communication channel. Using the redundant TTs information then a portion of the finite impulse response of the communication channel, within the time domain, may be zeroed, thereby providing a much improved channel estimate and noise estimate. Using the redundant TTs, less noise is introduced onto the data tones (DTs) within a data frame. The present invention is also able to identify those portions of the TTs that are attributable to the actual channel and those that are attributable to the channel's noise.
1. A communication device that is operable to receive a signal from a communication channel, comprising:
a channel estimate calculation block that is operable to:
process a data frame of the signal that is received from the communication channel, wherein the data frame includes a plurality of redundant training tones; and
employ the plurality of redundant training tones to perform channel estimation of the communication channel; and wherein:
a minimum plurality of training tones would be required to perform channel estimation of the communication channel based on a maximum allowable delay spread of the communication channel; and
the plurality of redundant training tones includes at least one more training tone than the minimum plurality of training tones.
2. The communication device of claim 1 , wherein:
the communication channel is a multi-path communication channel.
3. The communication device of claim 1 , wherein:
the communication device employs vector orthogonal frequency division multiplexing.
4. The communication device of claim 1 , wherein:
the communication channel is a multi-path communication channel;
the channel estimate calculation block is operable to determine a maximum allowable delay spread of the multi-path communication channel using the plurality of redundant training tones; and
the maximum allowable delay spread corresponds to a maximally dispersed communication path within the multi-path communication channel.
5. The communication device of claim 1 , wherein the communication device is operable to:
determine the maximum allowable delay spread of the communication channel using the plurality of redundant training tones;
characterize a finite impulse response of the communication channel using the data frame;
transform the finite impulse response of the communication channel from a frequency domain to a time domain;
zero a portion of the finite impulse response of the communication channel that is greater than the maximum allowable delay spread; and
transform the finite impulse response of the communication channel, having the zeroed portion, back from the time domain to the frequency domain.
6. The communication device of claim 1 , wherein:
the communication channel is a multi-path communication channel;
the channel estimate calculation block is operable to determine the maximum allowable delay spread of the multi-path communication channel using the plurality of redundant training tones; and
the channel estimate calculation block is operable to determine the maximum allowable delay spread, at least in part, offline.
7. The communication device of claim 1 , wherein:
the communication channel is a multi-path communication channel;
the communication device is operable to:
receive a first signal via a first path of the multi-path communication channel; and
receive a second signal via a second path of the multi-path communication channel.
8. The communication device of claim 1 , wherein:
the communication device is employed within a communication system that employs at least one of a QPSK coding scheme, a 16 QAM coding scheme, a 64 QAM coding scheme, a 256 QAM coding scheme, and a 1024 QAM coding scheme.
9. The communication device of claim 1 , further comprising:
a plurality of antennae that is configured in a spatially diversified manner, each antenna within the plurality of antennae outputs an antenna signal; and
the communication device is operable to combine each of the antenna signals thereby generating the signal that includes the data frame.
10. The communication device of claim 1 , wherein:
the communication channel is a wireless communication channel; and
the communication device is a wireless communication device.
11. A communication device that is operable to receive a signal from a communication channel, comprising:
a channel estimate calculation block that is operable to:
process a data frame of the signal that is received from the communication channel, wherein the data frame includes a plurality of redundant training tones;
determine a maximum allowable delay spread of the communication channel using the plurality of redundant training tones; and
employ the maximum allowable delay spread to perform channel estimation of the communication channel; and wherein:
a minimum plurality of training tones is required to perform channel estimation of the communication channel based on the maximum allowable delay spread of the communication channel; and
the plurality of redundant training tones includes at least one more training tone than the minimum plurality of training tones.
12. The communication device of claim 11 , wherein:
the communication channel is a multi-path communication channel; and
the maximum allowable delay spread corresponds to a maximally dispersed communication path within the multi-path communication channel.
13. The communication device of claim 11 , wherein the communication device is operable to:
characterize a finite impulse response of the communication channel using the data frame;
transform the finite impulse response of the communication channel from a frequency domain to a time domain;
zero a portion of the finite impulse response of the communication channel that is greater than the maximum allowable delay spread; and
transform the finite impulse response of the communication channel, having the zeroed portion, back from the time domain to the frequency domain.
14. The communication device of claim 11 , further comprising:
a plurality of antennae that is configured in a spatially diversified manner, each antenna within the plurality of antennae outputs an antenna signal; and
the communication device is operable to combine each of the antenna signals thereby generating the signal that includes the data frame; and wherein:
the communication channel is a multi-path communication channel;
the communication device is operable to:
receive a first signal via a first path of the multi-path communication channel; and
receive a second signal via a second path of the multi-path communication channel.
15. The communication device of claim 11 , wherein:
the communication channel is a wireless communication channel; and
the communication device is a wireless communication device.
16. A method, comprising:
receiving a signal from a communication channel;
processing a data frame of the signal that is received from the communication channel, wherein the data frame includes a plurality of redundant training tones; and wherein:
a minimum plurality of training tones would be required to perform channel estimation of the communication channel based on a maximum allowable delay spread of the communication channel; and
the plurality of redundant training tones includes at least one more training tone than the minimum plurality of training tones; and
employing the plurality of redundant training tones to perform channel estimation of the communication channel.
17. The method of claim 16 , further comprising:
determining the maximum allowable delay spread of the communication channel using the plurality of redundant training tones, wherein:
the communication channel is a multi-path communication channel; and
the maximum allowable delay spread corresponds to a maximally dispersed communication path within the multi-path communication channel.
18. The method of claim 16 , further comprising:
determining the maximum allowable delay spread of the communication channel using the plurality of redundant training tones;
characterizing a finite impulse response of the communication channel using the data frame;
transforming the finite impulse response of the communication channel from a frequency domain to a time domain;
zeroing a portion of the finite impulse response of the communication channel that is greater than the maximum allowable delay spread; and
transforming the finite impulse response of the communication channel, having the zeroed portion, back from the time domain to the frequency domain.
19. The method of claim 16 , wherein:
the method is performed within a communication device is employed within a communication system that employs at least one of a QPSK coding scheme, a 16 QAM coding scheme, a 64 QAM coding scheme, a 256 QAM coding scheme, and a 1024 QAM coding scheme.
20. The method of claim 16 , wherein:
the communication channel is a wireless communication channel; and
the method is performed within a wireless communication device.