Methods for channel information acquisition, signal detection and transmission in multi-user wireless communication systems

• US 10,230,436 B2
• Filed: 10/20/2015
• Issued: 03/12/2019
• Est. Priority Date: 10/20/2014
• Status: Active Grant

• Current Assignee: RF DSP, Inc.
• Original Assignee: RF DSP, Inc.
• Inventors: Liang, Ping, Zhu, Dengkui, Li, Boyu
• Primary Examiner(s): Mui, Gary
• Application Number:
  US15/504,146
• Publication Number:
  US 20170250740A1
• Time in Patent Office: 1,239 Days
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

This invention presents methods for signal detection and transmission in MU-MIMO wireless communication systems, for multiple UEs transmit uplink SRS to capture the uplink channel coefficients, and to estimate the frequency offsets and time offsets, for the BS estimating the channel coefficients of multiple UEs with the received SRS, for the BS estimating the frequency offsets and time offsets of multiple UEs with the estimated channel coefficients, for the BS modifying the estimated channel coefficients with the estimated frequency offsets and time offsets, for the BS calculating the detection matrices for the uplink MU-MIMO signal detection with the modified channel coefficients and for the BS calculating the precoding matrices for the downlink MU-MIMO signal transmission.

Claims

1. A method for signal detection and transmission in Multi-User Multiple-Input Multiple-Output (MU-MIMO) wireless communication systems comprising a Base Station (BS) estimating the channel coefficients of multiple User Equipment (UEs) with a received SRS transmitted at the subcarrier set of one or more symbols in a subframe;

the BS estimating the frequency offset and time offset of multiple UEs using SRS transmitted in more than one symbols;

the BS modifying the estimated channel coefficients using the estimated frequency offset and time offset;

the BS calculating the detection matrices for uplink MU-MIMO signal detection using the modified channel coefficients; and

the BS calculating the precoding matrices for downlink MU-MIMO signal transmission,

further comprising the BS with multiple distributed antenna arrays compensating the time offset of the effective channel coefficients corresponding to a specific antenna subgroup using the estimated time offset, and the BS calculating the MU-MIMO signal detection matrices with the effective channel coefficients after time offset compensation for an uplink signal transmission.

3. A method for signal detection and transmission in Multi-User Multiple-Input Multiple-Output (MU-MIMO) wireless communication systems comprising a Base Station (BS) estimating the channel coefficients of multiple User Equipment (UEs) with a received SRS transmitted at the subcarrier set of one or more symbols in a subframe;

the BS estimating the frequency offset and time offset of multiple UEs using SRS transmitted in more than one symbols;

the BS modifying the estimated channel coefficients using the estimated frequency offset and time offset;

the BS calculating the detection matrices for uplink MU-MIMO signal detection using the modified channel coefficients; and

the BS calculating the precoding matrices for downlink MU-MIMO signal transmission;

further comprising the BS calibrating the modified channel coefficients as in claim 1, and the BS calculating downlink MU-MIMO precoding matrices using the calibrated channel coefficients.

4. A method for signal detection and transmission in Multi-User Multiple-Input Multiple-Output (MU-MIMO) wireless communication systems comprising a Base Station (BS) estimating the channel coefficients of multiple User Equipment (UEs) with a received SRS transmitted at the subcarrier set of one or more symbols in a subframe;

the BS estimating the frequency offset and time offset of multiple UEs using SRS transmitted in more than one symbols;

the BS modifying the estimated channel coefficients using the estimated frequency offset and time offset;

the BS calculating the detection matrices for uplink MU-MIMO signal detection using the modified channel coefficients; and

the BS calculating the precoding matrices for downlink MU-MIMO signal transmission;

further comprising the BS calibrating the modified channel coefficients as in claim 1, and the BS calculating downlink MU-MIMO precoding matrices using the calibrated channel coefficients;

further comprising the BS modifying the precoding matrices using the estimated frequency offset according to a specific Orthogonal Frequency-Division Multiplexing (OFDM) symbol index of a subframe to which the precoding matrices are applied.

2. A method for signal detection and transmission in Multi-User Multiple-Input Multiple-Output (MU-MIMO) wireless communication systems comprising a Base Station (BS) estimating the channel coefficients of multiple User Equipment (UEs) with a received SRS transmitted at the subcarrier set of one or more symbols in a subframe;

the BS estimating the frequency offset and time offset of multiple UEs using SRS transmitted in more than one symbols;

the BS modifying the estimated channel coefficients using the estimated frequency offset and time offset;

the BS calculating the detection matrices for uplink MU-MIMO signal detection using the modified channel coefficients; and

the BS calculating the precoding matrices for downlink MU-MIMO signal transmission;

further comprising the BS with multiple distributed antenna arrays compensating the time offset of the effective channel coefficients corresponding to a specific antenna subgroup using the estimated time offset, and the BS calculating the MU-MIMO signal detection matrices using the effective channel coefficients after time offset compensation for an uplink signal transmission,

further comprising the BS modifying the detection matrix using the estimated frequency offset according to a specific Orthogonal Frequency-Division Multiplexing (OFDM) symbol index of a subframe to which the detection matrix is applied.