Structured-pipelined CORDIC for matrix equalization

Patent metadata

Field	Value
Publication number	US-11018729-B2
Application number	US-202016876261-A
Country	US
Kind code	B2
Filing date	May 18, 2020
Priority date	May 21, 2019
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

Flexible structured-pipelined CORDIC techniques efficiently perform various CORDIC operations and support different parameters for MIMO MEQ processing. The structured-pipelined CORDIC techniques simplify signal processing flow, unify input requirements and output delay, and simplify integration. Look-up table techniques provide quick generation of control signals, reduce design and verification efforts, and facilitate design automation. In addition, the structured-pipelined CORDIC techniques are conducive to hardware sharing and reuse. The structured-pipelined CORDIC techniques reduce integrated circuit area and power consumption.

First claim

What is claimed is:

1. A Multiple-Input, Multiple-Output (MIMO) Orthogonal Frequency-Division Multiplexing (OFDM) receiver comprising:
a structured-pipelined COordinate Rotation Digital Computer (CORDIC) configured to generate an output real signal, an output imaginary signal, and an output rotation signal, the structured-pipelined CORDIC comprising:
a first input selection circuit configured to output a first input real signal selected from M input real signals according to an input selection signal where M is an integer greater than zero;
a second input selection circuit configured to output a first input imaginary signal selected from M input imaginary signals according to the input selection signal;
a third input selection circuit configured to output a first input rotation signal selected from M−1 input rotation signals and the output rotation signal according to the input selection signal; and

I CORDIC stages coupled in series comprising:
a first CORDIC stage configured to receive the first input real signal, the first input imaginary signal, the first input rotation signal, and an input control signal, and
I−1 additional CORDIC stages, each of the I−1 additional CORDIC stage being configured to receive a corresponding output real signal, a corresponding output imaginary signal, a corresponding output rotation signal, and a corresponding stored control signal of a prior adjacent CORDIC stage of the I CORDIC stages,

wherein the output real signal, the output imaginary signal, and the output rotation signal are based on a last output real signal, a last output imaginary signal, a last output rotation signal, respectively, generated by a last CORDIC stage of the I−1 additional CORDIC stages, where I is a second integer greater than one.

2. The MIMO OFDM receiver, as recited in claim 1 , wherein the input control signal is used to sequentially configure each of the I CORDIC stages to operate in a mode selected from a rotation mode, a vector mode, a bypass mode, and a storage mode.

3. The MIMO OFDM receiver, as recited in claim 1 , further comprising:
a MIMO Matrix Equalizer (MEQ) comprising a plurality of structured-pipelined CORDICs, the structured-pipelined CORDIC being included in the plurality of structured-pipelined CORDICs.

4. The MIMO OFDM receiver, as recited in claim 3 , further comprising:
a control circuit configured to generate the input control signal for operation of each structured-pipeline CORDIC of the MIMO MEQ based on an encoded state signal, a cycle count value, a burst count value, and a re-use cycle count value.

5. The MIMO OFDM receiver, as recited in claim 3 , wherein the plurality of structured-pipelined CORDICs are grouped by permutation operation of a QR decomposition of a channel matrix and are configured to generate N SS inverse channel matrices for a corresponding subcarrier of an OFDM signal.

6. The MIMO OFDM receiver, as recited in claim 3 , further comprising:
a control circuit configured to sequentially cause the plurality of structured-pipelined CORDICs to perform N SS permutations of a QR decomposition to generate N SS inverse channel matrices based on a channel matrix, the channel matrix being an M×N SS matrix,
wherein N SS is a number of information streams received in a received packet received by M antennas of the receiver, N SS ≤N SS_MAX , M≤M MAX , M≥N SS , N SS_MAX is a maximum number of information streams supported by the MIMO OFDM receiver, and M MAX is a maximum number of receiver antennas supported by the MIMO OFDM receiver.

7. The MIMO OFDM receiver, as recited in claim 6 , wherein N SS <N SS_MAX and M<M MAX .

8. The MIMO OFDM receiver, as recited in claim 3 , wherein the MIMO MEQ further comprises:
a control circuit configured to apply an M×N SS inverse channel matrix to a received signal using the plurality of structured-pipelined CORDICs,
wherein N SS ≤N SS_MAX and M≤M MAX , M is a number of receiver antennas used to receive the received signal, N SS is a number of information streams received in the received signal, and M≥N SS , N SS_MAX is a maximum number of information streams supported by the MIMO MEQ, and M MAX is a maximum number of receiver antennas supported by the MIMO MEQ.

9. The MIMO OFDM receiver, as recited in claim 1 , further comprising:
a MIMO Matrix Equalizer (MEQ) comprising a plurality of first structured-pipelined CORDICs associated with a first permutation of a QR decomposition and configured to generate a first upper triangular matrix based on an M×N SS channel matrix, M being a number of receiver antennas, and N SS being a number of information streams received in a received packet;
a first select circuit configured to provide a first submatrix selected from a plurality of submatrices of the first upper triangular matrix based on N SS ;
a plurality of second structured-pipelined CORDICs associated with a second permutation of the QR decomposition and configured to generate a second upper triangular matrix based on the first submatrix and the first upper triangular matrix;
a second select circuit configured to provide a second submatrix selected from a plurality of second submatrices of the first upper triangular matrix based on N SS ;
a plurality of third structured-pipelined CORDICs associated with a third permutation of the QR decomposition and configured to generate a third upper triangular matrix based on the second submatrix and the first upper triangular matrix; and
a plurality of fourth structured-pipelined CORDICs associated with a fourth permutation of the QR decomposition and configured to generate a fourth upper triangular matrix based on the first upper triangular matrix,
wherein the structured-pipelined CORDIC is included in the plurality of first structured-pipelined CORDICs.

10. A method for operating A Multiple-Input, Multiple-Output (MIMO) Orthogonal Frequency-Division Multiplexing (OFDM) receiver, the method comprising:
generating an output real signal, an output imaginary signal, and an output rotation signal by performing a structured-pipelined CORDIC operation comprising:
selecting a first input real signal from M input real signals according to an input selection signal, where M is an integer greater than one;
selecting a first input imaginary signal from M input imaginary signals according to the input selection signal;
selecting a first input rotation signal from M−1 input rotation signals and the output rotation signal according to the input selection signal;
performing I iterations of a CORDIC operation comprising:
performing a first iteration of the CORDIC operation on the first input real signal, the first input imaginary signal, and the first input rotation signal according to an input control signal; and
performing I−1 additional iterations of the CORDIC operation, each of the I−1 additional CORDIC operations including receiving a corresponding output real signal, a corresponding output imaginary signal, a corresponding output rotation signal, and a corresponding stored control signal of a prior contiguous CORDIC operation of the I CORDIC operations,

wherein the output real signal, the output imaginary signal, and the output rotation signal are based on a last output real signal, a last output imaginary signal, a last output rotation signal, respectively, generated by a last CORDIC operation of the I−1 additional CORDIC operations.

11. The method, as recited in claim 10 , further comprising:
selecting the CORDIC operation is selected from a rotation operation, a vector operation, a bypass operation, and a storage operation.

12. The method, as recited in claim 10 , further comprising:
determining N SS upper triangula

Assignees

• Nxp Usa Inc

Inventors

• Ma Yong
• Tang Kai Cheong
• Shan Chao
• Yu Mao

Classifications

• H04B7/0854

  using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion · CPC title

• H04L25/03159

  operating in the frequency domain (H04L25/03165, H04L25/03178 take precedence) · CPC title

• H04L27/2675

  Pilot or known symbols · CPC title

• H04L5/0023

  Time-frequency-space · CPC title

• H04L27/0014

  Carrier regulation (of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657) · CPC title