このアプリケーションの一部のコンテンツは現時点では利用できません。
このような状況が続く場合は、にお問い合わせくださいフィードバック & お問い合わせ
1. (WO2019066709) DOWNLINK PILOT ASSIGNMENT IN MASSIVE MIMO
注意: このテキストは、OCR 処理によってテキスト化されたものです。法的な用途には PDF 版をご利用ください。

CLAIMS

1 . A method performed by a network node (1 10) for downlink pilot signal assignment and transmission, and for data transmission , wherein the network node (1 10) has a plurality of antenna elements distributed over an area, wherein the network node (1 10) and at least one wireless device (120) are operating in a wireless communications network (100), and wherein the method comprises:

- determining (201 ) a respective Channel State Information, CSI, and/or a respective channel hardening degree for the at least one wireless device (120) based on an uplink pilot signal received from the at least one wireless device (120);

- possibly determining (202) a respective mobility condition for the at least one wireless device (120);

- based on one or more out of: the determined respective CSI, the determined respective channel hardening degree and the determined respective mobility condition, obtaining (203) a respective pilot utility metric for the at least one wireless device (120);

- assigning (204) a respective downlink pilot signal to at least one wireless device out of the at least one wireless devices (120) having a respective pilot utility metric exceeding a predetermined threshold value; and

- transmitting (205), to the at least one wireless device out of the at least one wireless devices (120), data and possibly an assigned respective downlink pilot signal.

2. The method of claim 1 , further comprising:

- based on the obtained respective pilot utility metric for the at least one wireless devices (120), grouping each one of the at least one wireless devices (120) in a first group of wireless devices which are to be assigned a respective downlink pilot signal or in a second group of wireless devices which are not requiring a respective downlink pilot signal.

3. The method of claim 1 or 2, wherein the wireless devices of the first group of wireless devices have a respective pilot utility metric exceeding a predetermined threshold value.

4. The method of any one of claims 1 -3, wherein the assigning (204) of the respective downlink pilot signal comprises:

- transmitting (204), to each wireless device out of the at least one wireless

devices (120), a pilot configuration indicating whether or not a respective downlink pilot signal is assigned.

5. The method of any one of claims 1 -4, wherein the network node (1 10) is a Distributed Massive MIMO, D-maMIMO, network node, e.g. a D-maMIMO base station.

6. The method of any one of claims 1 -5, wherein the obtaining (203) of the respective pilot utility metric for the at least one wireless device (120), further comprises:

- obtaining the pilot utility metric as puk = wDk + (1 -w)(1 -ChDk), wherein Dk£ [0,1 ] is a Doppler spread value, we [0,1 ] is a weight to prioritize differently between the user mobility and the channel hardening degree, ChD, and k indicates which one out of the k wireless devices operating in the wireless communications network (100) for which the pilot utility metric puk is valid.

7. The method of any one of claims 1 -5, wherein the obtaining (203) of the respective pilot utility metric for the at least one wireless device (120), further comprises:

- obtaining the pilot utility metric based on a priority for the wireless device, which priority indicates whether or not the wireless device is to be prioritised when assigning a respective downlink pilot signal to the at least one wireless device (120).

8. The method of claim 7, wherein the obtaining (203) of the respective pilot utility metric for the at least one wireless device (120), further comprises:

- obtaining the pilot utility metric as:

puk = wDk + (1 -w)(1 -ChDk) + OCk, or

puk = (Xk((wDk + (1 -w)(1 -ChDk)),

wherein Dk£ [0,1 ] is a Doppler spread value, we [0,1 ] is a weight to prioritize

differently between the user mobility and the Channel hardening Degree, ChD, ocke [0,1 ] is a priority for the wireless device, and k indicates which one out of the k wireless devices operating in the wireless communications network (100) for which the pilot utility metric puk is valid.

9. The method of any one of claims 1 -5, wherein the obtaining (203) of the respective pilot utility metric for the at least one wireless device (120), further comprises: - obtaining the pilot utility metric as one out of:

puk = (Xk(wDk + (1 -w)(RkDLp - RkULp)),

puk = (Xk(wDk + (1 -w)(TkDLp - TkULp)),

puk = (Xk(wDk + (1 -w)({RkDLp - RkULp} / RkDLp)),

puk = OCk(wDk + (1 -w)({TkDLp - TkULp} / TkDLp)),

puk = ak(wDk + ((1 -w) / RkULp)),

wherein Dk£ [0,1 ] is a Doppler spread value, we [0,1 ] is a weight giving a relative importance of a user based mobility component and a channel state dependent component, RkDL is a rate the wireless device k would achieve by using the respective downlink pilot signal DLp, RkULp is a rate the wireless device would achieve when the network node (1 10) only relies on CSI estimated from an uplink pilot signal ULp received from the wireless device, is a throughput the wireless device k would achieve by using the respective downlink pilot signal DLp, TkUL is a throughput the wireless device would achieve when the network node (1 10) only relies on CSI estimated from an uplink pilot signal ULp received from the wireless device, and k indicates which one out of the k wireless devices operating in the wireless communications network (100) for which the pilot utility metric puk is valid.

10. A method performed by a wireless device (120) for receiving and demodulating data, wherein the wireless device (120) and a network node (1 10) are operating in a wireless communications network (100), wherein the network node (1 10) has a plurality of antenna elements distributed over an area, and wherein the method comprises:

- receiving (401 ), from the network node (1 10), an assignment of a downlink pilot, indicating whether or not a respective downlink pilot signal is assigned to the wireless device (120);

- receiving (402), from the network node (1 10), data and possibly an assigned downlink pilot signal;

- when an assigned downlink pilot signal is received, estimating (403) a downlink channel based on the received downlink pilot signal, and demodulating (404) the received data using the estimated downlink channel; and

- in absence of a received assigned downlink pilot signal, estimating (405) a downlink channel as a constant and demodulating (406) the received data using the constant as the estimate of the downlink channel.

1 1 . The method of claim 10, wherein the receiving (401 ) of the assignment of a downlink pilot signal comprises:

- receiving a pilot configuration indicating whether or not a downlink pilot is assigned.

12. The method of claim 10 or 1 1 , wherein, when an assigned downlink pilot signal is received, the estimating (403) of the downlink channel comprises estimating

instantaneous Channel State Information, CSI, of the downlink channel based on the received downlink pilot signal; and wherein the demodulating (404) of the received data using the estimated downlink channel comprises demodulating the received data using the estimated instantaneous CSI.

13. The method of any one of claims 10-12, wherein, in absence of a received assigned downlink pilot signal, the demodulating of the received data comprises demodulating the received data using statistical CSI.

14. A network node (1 10) for downlink pilot signal assignment and transmission, and for data transmission, wherein the network node (1 10) has a plurality of antenna elements distributed over an area, wherein the network node (1 10) and at least one wireless device (120) are configured to operate in a wireless communications network (100), and wherein the network node (1 10) is configured to:

- determine a respective Channel State Information, CSI, and/or a respective channel hardening degree for the at least one wireless device (120) based on an uplink pilot signal received from the at least one wireless device (120);

- possibly determine a respective mobility condition for the at least one wireless device (120);

- obtain a respective pilot utility metric for the at least one wireless device (120) based on one or more out of: the determined respective CSI, the determined respective channel hardening degree and the determined respective mobility condition;

- assign a respective downlink pilot signal to at least one wireless device out of the at least one wireless devices (120) having a respective pilot utility metric exceeding a predetermined threshold value; and

- transmit, to the at least one wireless device out of the at least one wireless devices (120), data and possibly an assigned respective downlink pilot signal.

15. The network node (1 10) of claim 14, being configured to:

- based on the obtained respective pilot utility metric for the at least one wireless devices (120), group each one of the at least one wireless devices ( 120) in a first group of wireless devices which are to be assigned a respective downlink pilot signal or in a second group of wireless devices which are not requiring a respective downlink pilot signal.

16. The network node (1 10) of claim 14 or 15, wherein the wireless devices of the first group of wireless devices have a respective pilot utility metric exceeding a

predetermined threshold value.

17. The network node (1 10) of any one of claims 14-16, wherein the network node (1 10) is configured to assign the respective downlink pilot signal by further being configured to:

- transmit, to each wireless device out of the at least one wireless devices (120), a pilot configuration indicating whether or not a respective downlink pilot signal is assigned.

18. The network node (1 10) of any one of claims 14-17, wherein the network node (1 10) is a Distributed Massive MIMO, D-maMIMO, network node, e.g. a D-maMIMO base station.

19. The network node (1 10) of any one of claims 14-18, wherein the network node (1 10) is configured to obtain the respective pilot utility metric for the at least one wireless device (120), by further being configured to:

- obtain the pilot utility metric as puk = wDk + (1 -w)(1 -ChDk), wherein Dk£ [0,1 ] is a Doppler spread value, we [0,1 ] is a weight to prioritize differently between the user mobility and the channel hardening degree, ChD, and k indicates which one out of the k wireless devices operating in the wireless communications network (100) for which the pilot utility metric puk is valid.

20. The network node (1 10) of any one of claims 14-18, wherein the network node (1 10) is configured to obtain the respective pilot utility metric for the at least one wireless device (120), by further being configured to:

- obtain the pilot utility metric based on a priority for the wireless device, which priority indicates whether or not the wireless device is to be prioritised when assigning a respective downlink pilot signal to the at least one wireless device (120).

21 . The network node (1 10) of claim 20, wherein the network node (1 10) is configured to obtain the respective pilot utility metric for the at least one wireless device (120), by further being configured to:

- obtain the pilot utility metric as:

puk = wDk + (1 -w)(1 -ChDk) + OCk, or

puk = OCk((wDk + (1 -w)(1 -ChDk)),

wherein Dk£ [0,1 ] is a Doppler spread value, w e [0,1 ] is a weight to prioritize

differently between the user mobility and the Channel hardening Degree, ChD, ocke [0,1 ] is a priority for the wireless device, and k indicates which one out of the k wireless devices operating in the wireless communications network (100) for which the pilot utility metric puk is valid.

22. The method of any one of claims 14-17, wherein the network node (1 10) is configured to obtain the respective pilot utility metric for the at least one wireless device (120), by further being configured to obtain the pilot utility metric as one out of:

puk = ock(wDk + (1 -w)(RkDLp - RkULp)),

puk = ock(wDk + (1 -w)(TkDLp - TkULp)),

puk = OCk(wDk + (1 -w)({RkDLp - RkUL } / RkDL )),

puk = OCk(wDk + (1 -w)({TkDLp - TkULp} / TkDLp)),

puk = OCk(wDk + ((1 -w) / RkULp)),

wherein Dk£ [0,1 ] is a Doppler spread value, we [0,1 ] is a weight giving a relative importance of a user based mobility component and a channel state dependent component, RkDL is a rate the wireless device k would achieve by using the respective downlink pilot signal DLp, RkULp is a rate the wireless device (120) would achieve when

the network node (1 10) only relies on CSI estimated from an uplink pilot signal ULp received from the wireless device, TkDLP is a throughput the wireless device k would achieve by using the respective downlink pilot signal DLp, is a throughput the wireless device would achieve when the network node (1 10) only relies on CSI estimated from an uplink pilot signal ULp received from the wireless device, and k indicates which one out of the k wireless devices operating in the wireless communications network (100) for which the pilot utility metric puk is valid.

23. A wireless device (120) for receiving and demodulating data, wherein the wireless device (120) and a network node (1 10) are configured to operate in a wireless communications network (100), wherein the network node (1 10) has a plurality of antenna elements distributed over an area, and wherein the wireless device (120) is configured to:

- receive, from the network node (1 10), an assignment of a downlink pilot indicating whether or not a respective downlink pilot signal is assigned to the wireless device (120);

- receive, from the network node (1 10), data and possibly an assigned downlink pilot signal;

- when an assigned downlink pilot signal is received, estimate a downlink channel based on the received downlink pilot signal, and demodulate the received data using the estimated downlink channel; and

- in absence of a received assigned downlink pilot signal, estimate a downlink channel as a constant and demodulate the received data using the contstant as the estimate of the downlink channel.

24. The wireless device (120) of claim 23, wherein the wireless device (120) is configured to receive the assignment of a downlink pilot signal by further being configured to:

- receive a pilot configuration indicating whether or not a downlink pilot is assigned.

25. The wireless device (120) of claim 23 or 24, further being configured to estimate the downlink channel by estimating instantaneous Channel State Information, CSI, of the downlink channel based on the received downlink pilot signal when an assigned downlink pilot signal is received, and being configured to demodulate the

received data using the estimated instantaneous CSI.

26. The wireless device (120) of any one of claims 23-25, further being configured to demodulate the received data using statistical CSI in the absence of a received assigned downlink pilot signal.

27. A computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to any one of claim 1 -13.

28. A carrier comprising the computer program of claim 27, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.