System and method for a scale-invariant symbol demodulator

• US 9,838,091 B2
• Filed: 11/25/2014
• Issued: 12/05/2017
• Est. Priority Date: 11/26/2013
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Xu, Ge, Janse van Rensburg, Cornelius
• Primary Examiner(s): Orgad, Edan
• Assistant Examiner(s): Lalchinthang, Vanneilian
• Application Number:
  US14/553,448
• Publication Number:
  US 20150146652A1
• Time in Patent Office: 1,106 Days
• Field of Search: 370329
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0665 Feed forward of transmit weights to the receiver
• CPC Class Codes: H04L 27/36 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/38 Demodulator circuits; Receiver circuits

Abstract

It is possible to improve the spectral efficiency of multi-layer multiple input multiple output (MIMO) transmissions by estimating the magnitude parameter at the receiver side, rather signaling the magnitude parameter from the transmitter to the receiver. In long term evolution (LTE) networks, the user equipment (UE) may estimate the power allocation (Pa) parameter by executing a series of steps. For example, the UE may define a single unknown variable from a received downlink MIMO signal, extend the single unknown scalar variable to a multivariate signal model for multiple channels (N), convert the multivariate signal model to a MIMO configured signal model, and then obtain the Pa parameter from the MIMO configured multivariate signal model.

Claims

1. A method for communicating over a multiple input multiple output (MIMO) channel, the method comprising:

transmitting, by a base station (BS), a downlink MIMO signal to a user equipment (UE), wherein the downlink MIMO signal comprises multiple layers communicated directly to the UE in accordance with a phase parameter and a magnitude parameter; and

signaling, by the BS, the phase parameter to the UE without signaling the magnitude parameter to the UE, wherein both the phase parameter and the magnitude parameter are utilized by the UE to demodulate the downlink MIMO signal, the UE being adapted to estimate the magnitude parameter based at least on an additive white Gaussian noise (AWGN) vector associated with the downlink MIMO signal.

2. The method of claim 1, wherein the multiple layers in the downlink MIMO signal are collectively communicated in a unicast transmission.

3. The method of claim 1, wherein the downlink MIMO signal comprises a single user MIMO (SU-MIMO) signal that includes two or more layers communicated directly to the UE.

4. The method of claim 1, wherein the downlink MIMO signal comprises a multi-user MIMO (MU-MIMO) signal that includes two or more layers communicated directly to the UE.

5. The method of claim 1, wherein signaling the phase parameter to the UE without signaling the magnitude parameter to the UE comprises:

transmitting a pilot signal indicating the phase parameter to the UE without signaling a power allocation (Pa) parameter to the UE.

6. The method of claim 1, wherein the downlink MIMO signal further comprises a physical downlink shared channel (PDSCH) and a cell-specific reference signal (C-RS), and

wherein signaling the phase parameter to the UE without signaling the magnitude parameter to the UE comprises communicating a pilot signal over the C-RS without communicating a power offset between the pilot signal carried in the C-RS and data carried in the PDSCH to the UE.

7. The method of claim 1, wherein transmitting the downlink MIMO signal to the UE comprises:

modulating an input signal using a quadrature amplitude modulation (QAM) technique in accordance with the magnitude parameter to obtain a modulated signal; and

transmitting the modulated signal over the MIMO channel.

8. A base station comprising:

a processor; and

a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to;

transmit a downlink multiple input multiple output (MIMO) signal to a user equipment (UE), wherein the downlink MIMO signal comprises multiple layers communicated directly to the UE in accordance with a phase parameter and a magnitude parameter; and

signal the phase parameter to the UE without signaling the magnitude parameter to the UE, wherein both the phase parameter and the magnitude parameter are utilized by the UE to demodulate the downlink MIMO signal, the UE being adapted to estimate the magnitude parameter based at least on an additive white Gaussian noise (AWGN) vector associated with the downlink MIMO signal.

9. A method for communicating over a multiple input multiple output (MIMO) channel, the method comprising:

receiving, by a user equipment (UE), a downlink MIMO signal from a base station (BS), wherein the downlink MIMO signal comprises multiple layers communicated directly to the UE;

receiving, by the UE, a phase parameter associated with the downlink MIMO signal from the BS;

estimating, by the UE, a magnitude parameter associated with the downlink MIMO signal based at least on an additive white Gaussian noise (AWGN) vector associated with the downlink MIMO signal; and

demodulating the downlink MIMO signal in accordance with the phase parameter and the magnitude parameter.

10. The method of claim 9, wherein the magnitude parameter is not signaled from the BS.

11. The method of claim 9, wherein the downlink MIMO signal comprises a single user MIMO (SU-MIMO) signal that includes two or more layers communicated directly to the UE.

12. The method of claim 9, wherein the downlink MIMO signal comprises a multi-user MIMO (MU-MIMO) signal that includes two or more layers communicated directly to the UE.

13. The method of claim 9, wherein demodulating the downlink MIMO signal in accordance with the phase parameter and the magnitude parameter comprises:

demodulating the downlink MIMO signal using a quadrature amplitude modulation (QAM) technique in accordance with the phase parameter and the magnitude parameter.

14. The method of claim 9, wherein estimating the magnitude parameter associated with the downlink MIMO signal comprises:

estimating a single scalar variable in accordance with signal characteristics of a physical downlink shared channel (PDSCH) communicated over a resource block group (RBG).

15. The method of claim 14, wherein estimating the single scalar variable in accordance with the signal characteristics of the PDSCH communicated over the RBG comprises:

defining a single unknown scalar variable using received symbols, transmitted symbols, channel information, and AWGN;

extending the single unknown scalar variable to a multivariate signal model using a received symbol vector, a transmitted symbol vector, a channel matrix, and the AWGN vector for multiple channels (N);

converting the multivariate signal model to a MIMO configured signal model using a number of transmit antennas and a number of receive antennas with the received symbol vector, the transmitted symbol vector, the channel matrix, and the AWGN vector;

calculating a least square estimator from the MIMO configured multivariate signal model using the received symbol vector and a channel matrix vector; and

obtaining the least square estimator from the MIMO configured multivariate signal model for the multiple channels (N).

16. The method of claim 15, wherein obtaining the least square estimator using the channel matrix vector and the received symbol vector comprises obtaining the least square estimator in accordance with the following equation:

17. A user equipment (UE) comprising:

a processor; and

a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to;

receive a downlink multiple input multiple output (MIMO) signal from a base station (BS), wherein the downlink MIMO signal comprises multiple layers

communicated directly to the UE;

receive a phase parameter associated with the downlink MIMO signal from the BS;

estimate a magnitude parameter associated with the downlink MIMO signal based at least on an additive white Gaussian noise (AWGN) vector associated with the downlink MIMO signal; and

demodulate the downlink MIMO signal in accordance with the phase parameter and the magnitude parameter.

18. The UE of claim 17, wherein the magnitude parameter is not signaled from the BS.