Methods for reference signal mapping in non-linear precoding MIMO transmission

Patent metadata

Field	Value
Publication number	US-12068892-B2
Application number	US-201917608926-A
Country	US
Kind code	B2
Filing date	May 6, 2019
Priority date	May 6, 2019
Publication date	Aug 20, 2024
Grant date	Aug 20, 2024

Abstract

Embodiments include methods for operating a network node in a wireless network. Such embodiments include applying non-linear precoding to a first data stream to remove a representation of expected inter-stream interference due to a second data stream, thereby generating a corrected first data stream. Such embodiments also include applying linear precoding to the corrected first data stream and to a first reference signal (RS) stream to generate a first signal layer. The first RS stream is not corrected for the expected inter-stream interference prior to applying the linear precoding. Such embodiments also include transmitting the first signal layer to a user equipment (UE). Other embodiments include complementary methods performed by a UE, as well as network nodes and UEs configured to perform operations corresponding to such methods.

First claim

The invention claimed is:

1. A method for operating a network node in a wireless network, the method comprising:
multiplexing a first data stream with a second reference signal (RS) stream;
applying non-linear precoding to the multiplexed combination of the first data stream and the second RS stream to remove a representation of expected inter-stream interference due to a second data stream, thereby generating a corrected first data stream and a corrected second RS stream;
applying linear precoding to the corrected first data stream, to the corrected second RS stream, and to a first RS stream to generate a first signal layer, wherein the first RS stream is not corrected for the expected inter-stream interference before applying the linear precoding; and
transmitting the first signal layer to a user equipment (UE).

2. The method of claim 1 , wherein:
the first RS stream is related to one or more first ports of RS that are associated with the first data stream; and
each of the first ports corresponds to one of the following types of RS: demodulation RS (DM-RS), phase-tracking RS (PT-RS), and channel state information RS (CSI-RS).

3. The method of claim 2 , wherein:
a particular first port corresponds to DM-RS; and
a further first port corresponds to PT-RS.

4. The method of claim 2 , wherein:
a particular first port corresponds to DM-RS;
a further first port corresponds to DM-RS; and
the particular first port and the further first port are time-multiplexed with the corrected first data stream.

5. The method of claim 1 , wherein:
the first and second data streams are associated with respective first and second users; and
applying non-linear precoding to the first data stream comprises performing a modulo operation on a combination of the first data stream and a representation of a second signal layer associated with the second user; and
the modulo operation is performed with respect to a maximum transmit power constraint and a modulation and coding scheme (MCS) used to transmit the first data stream.

6. The method of claim 5 , further comprising sending, to the UE, an indication of the MCS.

7. The method of claim 5 , wherein:
the method further comprises applying linear precoding to the second data stream to generate the second signal layer; and
applying non-linear precoding to the first data stream further comprises applying a feedback filter to the second signal layer to generate the representation of the second signal layer.

8. The method of claim 1 , wherein the second RS stream comprises second channel state information RS (CSI-RS) that are configured to facilitate inter-user interference measurements by the UE.

9. The method of claim 1 , wherein the first RS stream comprises first channel state information RS (CSI-RS) that are configured to facilitate same-user channel measurements by the UE.

10. A method for operating a user equipment (UE) in a wireless network, the method comprising:
receiving a first signal layer transmitted by a network node in the wireless network, wherein:
the first signal layer has been generated by the network node by applying linear precoding to a corrected first data stream, to a corrected second reference signal (RS) stream, and to a first RS stream; and
the corrected first data stream and the corrected second RS stream have been generated by the network node by applying non-linear precoding to a multiplexed combination of a first data stream with a second RS stream; and

performing one or more first measurements based on the first RS stream.

11. The method of claim 10 , further comprising applying linear filtering to the received first signal layer to generate the first data stream and the first RS stream.

12. The method of claim 10 , wherein:
the first RS stream is related to one or more first ports of RS that are associated with the first data stream; and
each of the first ports corresponds to one of the following types of RS: demodulation RS (DM-RS); phase-tracking RS (PT-RS); and channel state information RS (CSI-RS).

13. The method of claim 12 , wherein:
a particular first port corresponds to DM-RS; and
a further first port corresponds to PT-RS.

14. The method of claim 12 , wherein:
a particular first port corresponds to DM-RS;
a further first port corresponds to DM-RS; and
the particular first port and the further first port are time-multiplexed with the corrected first data stream.

15. The method of claim 10 , further comprising performing one or more second measurements based on the corrected second RS stream.

16. The method of claim 15 , wherein:
the second RS stream comprises one or more second channel state information RS (CSI-RS); and
the second measurements comprise inter-user interference measurements based on the corrected second CSI-RS.

17. The method of claim 10 , wherein:
the first RS stream comprises one or more first channel state information RS (CSI-RS); and
the first measurements comprise same-user channel measurements based on the first CSI-RS.

18. The method of claim 10 , wherein:
the first data stream comprises a plurality of data symbols; and
the method further comprises demodulating the data symbols comprising the corrected first data stream.

19. A network node in a wireless network, the network node comprising:
a radio network interface configured to communicate with one or more user equipment (UEs); and
processing circuitry operatively coupled with the radio network interface, whereby the processing circuitry and the radio network interface are configured to:
multiplex a first data stream with a second reference signal (RS) stream;
apply non-linear precoding to the multiplexed combination of the first data stream and the second RS stream to remove a representation of expected inter-stream interference due to a second data stream, thereby generating a corrected first data stream and a corrected second RS stream;
apply linear precoding to the corrected first data stream, to the corrected second RS stream, and to a first RS stream to generate a first signal layer, wherein the first RS stream is not corrected for the expected inter-stream interference before applying the linear precoding; and
transmit the first signal layer to a UE.

20. A user equipment (UE) comprising:
a radio transceiver configured for communicating with a network node in a wireless network; and
processing circuitry operatively coupled with the radio transceiver, whereby the processing circuitry and the radio transceiver are configured to perform operations corresponding to the method of claim 10 .

Assignees

• Ericsson Telefon Ab L M

Inventors

• Wang Zhao
• Girnyk Maksym
• Timo Roy
• Wernersson Niklas
• Järmyr Simon

Classifications

• H04L5/0048

  Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091) · CPC title

• H04B7/0626

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B17/345

  Interference values ({signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]} H04B17/336) · CPC title

• H04L25/0224

  using sounding signals · CPC title

• H04J11/0033

  by pre-cancellation of known interference, e.g. using a matched filter, dirty paper coder or Thomlinson-Harashima precoder (correlative coding in synchronous or start-stop systems H04L25/497) · CPC title