Point to Point Split Mount Impairment Correction System
Systems and methods are provided for lowering the cost and power consumption of outdoor units (ODUs) by providing digital corrections of ODU impairments within indoor units (IDUs). For example, in an embodiment, an error correction module located in the IDU can digitally correct the ODU impairments. Embodiments of the present disclosure allow direct transmission and direct reception in ODUs without any image or LO leakage filtering.
1 . An indoor unit (IDU), comprising:
an oscillator configured to provide a first signal at a first frequency;
a down-converter configured to receive the first signal and a second signal having a second frequency generated by an outdoor unit (ODU) coupled to the IDU, wherein the down-converter is configured to down-convert the second signal to using the first signal; and
an error correction module coupled to the oscillator and the down-converter, wherein the error correction module is configured to adjust the oscillator, based on a frequency output of the down-converter, so that the first frequency matches the second frequency.
2 . The IDU of claim 1 , wherein the error correction module is further configured to:
estimate, based on the frequency output of the down-converter, a reference frequency of the ODU.
3 . The IDU of claim 2 , wherein the error correction module is further configured to:
compensate, based on the reference frequency, for an impairment occurring during communication between the IDU and a second IDU.
4 . The IDU of claim 3 , wherein the error correction module is further configured to:
cancel an intermediate frequency (IF) error occurring during communication between the IDU and the second IDU to compensate for the impairment.
5 . The IDU of claim 3 , wherein the error correction module is further configured to:
cancel an in-phase/quadrature (I/Q) error occurring during communication between the IDU and the second IDU to compensate for the impairment.
6 . The IDU of claim 5 , wherein the error correction module is further configured to:
estimate I/Q mismatch occurring during communication between the IDU and the second IDU to cancel the I/Q error.
7 . The IDU of claim 2 , wherein the reference frequency is a reference frequency input into a synthesizer of the ODU.
8 . The IDU of claim 1 , wherein the IDU is implemented in a point to point microwave backhaul system.
9 . An error correction module for an indoor unit (IDU), the error correction module comprising:
a first least mean square (LMS) adaptation module configured to correct a receive in-phase/quadrature (I/Q) mismatch for a signal received from an outdoor unit (ODU);
a carrier error estimation and adaptation module configured to correct a rotation error of the signal; and
a second LMS adaptation module configured to correct a transmit in-phase/quadrature (I/Q) mismatch for the signal.
10 . The error correction module of claim 9 , wherein the error correction module is configured to match a frequency of the IDU to a frequency of the signal.
11 . The error correction module of claim 9 , wherein the error correction module is implemented on a modem of the IDU.
12 . The error correction module of claim 9 , wherein the IDU is implemented in a point to point microwave backhaul system.
14 . A method for compensating for impairments in an indoor unit (IDU), the method comprising:
receiving, using a processing device, a signal from an outdoor unit (ODU);
matching, using the processing device, a frequency of the IDU to a frequency of the ODU;
estimating, using the processing device, a reference frequency of the ODU; and
compensating, using the processing device, for an impairment in the signal.
15 . The method of claim 14 , further comprising:
cancelling an intermediate frequency (IF) error occurring during communication between the first IDU and a second IDU to compensate for the impairment.
16 . The method of claim 14 , further comprising:
cancelling an in-phase/quadrature (I/Q) error in the signal to compensate for the impairment.
17 . The method of claim 16 , further comprising:
estimating an I/Q mismatch occurring during communication between the IDU and a second IDU to cancel the I/Q error.
18 . The method of claim 16 , further comprising:
cancelling the I/Q error using a least mean square (LMS) technique.
19 . The method of claim 14 , further comprising:
cancelling a rotation error in the signal using a carrier error estimation and adaptation technique to compensate for the impairment.
20 . The method of claim 14 , wherein the reference frequency is a reference frequency input into a synthesizer of the ODU.