Method and system for estimating and compensating IQ imbalance

A method of determining IQ imbalance introduced on an RF multicarrier signal received via a channel on a direct conversion analog receiver, the method comprising:

• a) receiving a training signal on the receiver, the training signal comprising at least consecutive first and second LTS's (long training symbols) which have been transmitted as identical LTS's;
• b) defining a first predetermined relationship between a first corrected LTS and the first received LTS, the first predetermined relationship comprising at least one IQ imbalance parameter;
• c) defining a second predetermined relationship between a second corrected LTS and the second received LTS, the second predetermined relationship comprising the at least one IQ imbalance parameter and a carrier frequency offset compensation;
• d) determining the carrier frequency offset compensation from the training signal;
• and
• e) determining the at least one IQ imbalance parameter by minimizing the difference between the first corrected LTS and the second corrected LTS according to the first and second predetermined relationships.

A method of determining IQ imbalance introduced on an RF multicarrier signal received via a channel on a direct conversion analog receiver, the method comprising:

• a) receiving a training signal at the receiver;
• b) determining a carrier frequency offset from the training signal;
• and
• c) selecting, based on the carrier frequency offset, one of a first process and a second process,
• wherein the first process includes:
• demodulating the training signal on the receiver;
• estimating a first frequency domain channel characteristic of the channel based on the demodulated training signal;
• defining a predetermined relationship between a corrected frequency domain channel characteristic of the channel and the first channel characteristic, the predetermined relationship comprising at least one IQ imbalance parameter;
• and
• determining the at least one IQ imbalance parameter such that the corrected channel characteristic satisfies a channel constraint,
• and wherein the second process includes:
• receiving a training signal on the receiver, the training signal comprising at least consecutive first and second LTS's (long training symbols) which have been transmitted as identical LTS's;
• defining a first predetermined relationship between a first corrected LTS and the first received LTS, the first predetermined relationship comprising at least one IQ imbalance parameter;
• defining a second predetermined relationship between a second corrected LTS and the second received LTS, the second predetermined relationship comprising the at least one IQ imbalance parameter and a carrier frequency offset compensation;
• determining the carrier frequency offset compensation from the training signal;
• and
• determining the at least one IQ imbalance parameter by minimizing the difference between the first corrected LTS and the second corrected LTS according to the first and second predetermined relationships.

A method of compensating IQ imbalance introduced on an RF multicarrier signal received via a channel on a direct conversion analog receiver, the method comprising:

• a) determining at least one IQ imbalance parameter and a carrier frequency offset estimate by a process;
• b) compensating the received RE signal for carrier frequency offset by means of the carrier frequency offset estimate;
• and
• c) compensating the CFO compensated signal for IQ imbalance by means of the at least one IQ imbalance parameter,
• wherein the process comprises:
• receiving a training signal on the receiver, the training signal comprising at least consecutive first and second LTS's (long training symbols) which have been transmitted as identical LTS's;
• defining a first predetermined relationship between a first corrected LTS and the first received LTS, the first predetermined relationship comprising at least one IQ imbalance parameter;
• defining a second predetermined relationship between a second corrected LTS and the second received LTS, the second predetermined relationship comprising the at least one IQ imbalance parameter and a carrier frequency offset compensation;
• determining the carrier frequency offset compensation from the training signal;
• and
• determining the at least one IQ imbalance parameter by minimizing the difference between the first corrected LTS and the second corrected LTS according to the first and second predetermined relationships.

A system for determining IQ imbalance introduced on an RF multicarrier signal received via a channel on a direct conversion analog receiver, the system comprising:

• means for receiving a training signal on the receiver;
• means for demodulating the training signal on the receiver;
• means for estimating a first frequency domain channel characteristic of the channel based on the demodulated training signal;
• means for defining a predetermined relationship between a corrected frequency domain channel characteristic of the channel and the first channel characteristic, the predetermined relationship comprising at least one IQ imbalance parameter;
• and
• means for determining the at least one IQ imbalance parameter such that the corrected channel characteristic satisfies a channel constraint.

One or more processor readable storage devices having processor readable code embodied on the processor readable storage devices, the processor readable code for programming one or more processors to perform a method of determining IQ imbalance introduced on an RF multicarrier signal received via a channel on a direct conversion analog receiver, the method comprising:

• receiving a training signal on the receiver;
• demodulating the training signal on the receiver;
• estimating a first frequency domain channel characteristic of the channel based on the demodulated training signal;
• defining a predetermined relationship between a corrected frequency domain channel characteristic of the channel and the first channel characteristic, the predetermined relationship comprising at least one IQ imbalance parameter;
• and
• determining the at least one IQ imbalance parameter such that the corrected channel characteristic satisfies a channel constraint.