TECHNICAL FIELD

The present disclosure relates to the field of wireless communications technologies, and in particular, to a method, system and apparatus for transmitting an uplink measurement reference signal.

BACKGROUND

A radio channel is a data signal transmission channel using a radio signal as a transmission medium. In the field of wireless communications, there is reciprocity between an uplink (a direction from user equipment to a base station) channel and a downlink (a direction from the base station to the user equipment) channel in a same frequency band. To be specific, an uplink channel matrix is the conjugate transpose of a downlink channel matrix.

In a communications system in the prior art, a base station usually obtains an uplink channel matrix by using an uplink measurement reference signal received from user equipment, and then, obtains a downlink channel matrix through calculation by using the foregoing reciprocity. The base station then schedules the user equipment based on the downlink channel matrix and sends downlink data.

However, when receiving the downlink data, the user equipment is affected by interference from surrounding signals and thermal noise of the user equipment. In the prior art, the downlink channel matrix obtained by the base station cannot reflect interference information of a user equipment side. Therefore, efficiency of scheduling the user equipment based on the downlink channel matrix by the base station is low.

SUMMARY

The present disclosure describes a method for transmitting an uplink measurement reference signal, an apparatus, and a system that help a base station obtain downlink interference information of a downlink channel.

According to an aspect, an embodiment of the present invention provides a method for transmitting an uplink measurement reference signal, where the method is applied to a network-side device and includes the following operations:

first, receiving, by the network-side device, an uplink measurement reference signal sent by user equipment, where the uplink measurement reference signal carries downlink interference information of a downlink channel of the network-side device; and then, performing downlink interference estimation on the uplink measurement reference signal, to obtain the downlink interference information.

Compared with the prior art in which a base station cannot obtain downlink interference information of a downlink channel used by user equipment, in this embodiment, the network-side device (which may be a base station) can effectively schedule the user equipment based on the downlink interference information, thereby improving scheduling efficiency, and improving data transmission efficiency of the downlink channel.

In one embodiment, the uplink measurement reference signal received by the network-side device includes a first uplink measurement reference signal and a first uplink measurement reference signal beamformed by using the downlink interference information.

The performing, by the network-side device, downlink interference estimation on the uplink measurement reference signal, to obtain interference information of the downlink channel may include:

first, performing channel estimation on the first uplink measurement reference signal, to obtain an uplink channel matrix H; performing channel estimation on the first uplink measurement reference signal beamformed by using the downlink interference information, to obtain a product H*I of the uplink channel matrix H and the downlink interference information I; and then, obtaining the downlink interference information I based on the uplink channel matrix H and the product H*I of the uplink channel matrix H and the downlink interference information I.

In one embodiment, the uplink measurement reference signal received by the network-side device includes a second uplink measurement reference signal beamformed by using a beamforming matrix V and a second uplink measurement reference signal beamformed for the second time by using the downlink interference information. In this case, the performing, by the network-side device, downlink interference estimation on the uplink measurement reference signal, to obtain interference information of the downlink channel may include:

first, performing channel estimation on the second uplink measurement reference signal beamformed by using the beamforming matrix V, to obtain a product H*V of an uplink channel matrix H and the beamforming matrix V; performing channel estimation on the secondarily beamformed second uplink measurement reference signal, to obtain a product H*V*I of the uplink channel matrix H, the beamforming matrix V, and the downlink interference information I; and then, obtaining the downlink interference information based on H*V and a product H*V*I of H*V and the downlink interference information I.

In one embodiment, the network-side device further sends codebook information to the user equipment, where the codebook information is used to indicate the beamforming matrix V used by the user equipment.

In one embodiment, before receiving the uplink measurement reference signal sent by the user equipment, the network-side device may further send an instruction message to the user equipment, where the instruction message is used to instruct the user equipment to send the downlink interference information to the network-side device, so as to coordinate direct message transmission between the user equipment and the network-side device.

In one embodiment, after obtaining two or more pieces of downlink interference information, the network-side device may select one of the pieces of downlink interference information to send downlink data to the user equipment. Before sending the downlink data, the network-side device may send a resource index corresponding to the first uplink measurement reference signal or the second uplink measurement reference signal to the user equipment. Sending the resource index can help the user equipment determine the beamforming matrix V used to receive the downlink data sent by the network-side device.

According to another aspect, an embodiment of the present disclosure provides a method for transmitting an uplink measurement reference signal, where the method is applied to user equipment and may include:

first, obtaining, by the user equipment, downlink interference information of a downlink channel of a network-side device; and then, sending an uplink measurement reference signal to the network-side device, where the uplink measurement reference signal carries the downlink interference information, so that the network-side device can obtain the downlink interference information of the downlink channel based on the uplink measurement reference signal, thereby effectively scheduling the user equipment.

In one embodiment, the sending, by the user equipment, an uplink measurement reference signal to the network-side device includes:

first, sending, by the user equipment, a first uplink measurement reference signal to the network-side device; beamforming the first uplink measurement reference signal by using the downlink interference information; and then, sending the beamformed first uplink measurement reference signal to the network-side device.

In one embodiment, the user equipment sends, by using a same time domain resource or adjacent time domain resources, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information.

In one embodiment, the user equipment sends, by using a same frequency domain resource or adjacent frequency domain resources, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information.

In one embodiment, the user equipment sends, by using a same cyclic shift or different cyclic shifts, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information.

In a possible design, the obtaining, by the user equipment, downlink interference information of a downlink channel of a network-side device includes: obtaining, by the user equipment, the downlink interference information of the downlink channel of the network-side device through calculation by using a transmission mode of transmit diversity or closed-loop spatial multiplexing. Optionally, the user equipment may calculate the downlink interference information of the downlink channel of the network-side device.

In one embodiment, the user equipment may send uplink signaling to the network-side device, where the uplink signaling carries the transmission mode of transmit diversity or closed-loop spatial multiplexing.

In one embodiment, the sending, by the user equipment, an uplink measurement reference signal to the network-side device includes:

first, sending, to the network-side device, a second uplink measurement reference signal beamformed by using a beamforming matrix V; then, beamforming, for the second time by using the downlink interference information, the second uplink measurement reference signal beamformed by using the beamforming matrix V; and sending the secondarily beamformed second uplink measurement reference signal to the network-side device.

In one embodiment, the sending, by the user equipment, an uplink measurement reference signal to the network-side device includes:

first, beamforming a third uplink measurement reference signal by using the beamforming matrix V; then, beamforming, for the second time by using the downlink interference information, the third uplink measurement reference signal beamformed by using the beamforming matrix V; and sending the secondarily beamformed third uplink measurement reference signal to the network-side device.

In one embodiment, the user equipment may receive a resource index or codebook information sent by the network-side device, and determine, based on the resource index or the codebook information, a beamforming matrix V used to send the uplink measurement reference signal.

According to a third aspect, an embodiment of the present invention provides user equipment, where the user equipment includes a transceiver and a processor. The processor is configured to obtain downlink interference information of a downlink channel of a network-side device; and the transceiver is configured to send an uplink measurement reference signal to the network-side device, where the uplink measurement reference signal carries the downlink interference information.

In one embodiment, the transceiver of the user equipment sends the uplink measurement reference signal to the network-side device includes:

sending a first uplink measurement reference signal to the network-side device; then, beamforming the first uplink measurement reference signal by using the downlink interference information; and sending, to the network-side device, the first uplink measurement reference signal beamformed by using the downlink interference information.

In one embodiment, the transceiver of the user equipment sends the uplink measurement reference signal to the network-side device includes:

sending, to the network-side device, a second uplink measurement reference signal beamformed by using a beamforming matrix V; then, beamforming, for the second time by using the downlink interference information, the second uplink measurement reference signal beamformed by using the beamforming matrix V; and sending the secondarily beamformed second uplink measurement reference signal to the network-side device.

In one embodiment, the transceiver of the user equipment is further configured to: before sending, to the network-side device, the second uplink measurement reference signal beamformed by using the beamforming matrix V, receive codebook information sent by the network-side device, and the processor is further configured to obtain the beamforming matrix V based on the codebook information.

In one embodiment, the transceiver of the user equipment is further configured to: before the processor obtains the downlink interference information of the downlink channel of the network-side device, receive an instruction message sent by the network-side device, where the instruction message is used to instruct the user equipment to send the downlink interference information to the network-side device.

In one embodiment, the transceiver of the user equipment sends, by using a same time domain resource or adjacent time domain resources, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information; or

the transceiver of the user equipment sends, by using a same frequency domain resource or adjacent frequency domain resources, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information; or

the transceiver of the user equipment sends, by using a same cyclic shift or different cyclic shifts, the initial first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information.

The time domain resource, the frequency domain resource, and the cyclic shift may be used in combination. For example, the transceiver of the user equipment sends, by using a same time domain resource and different cyclic shifts, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information.

Optionally, the user equipment may alternatively send, by using the time domain resource, the frequency domain resource, and the cyclic shift, the second uplink measurement reference signal beamformed by using the beamforming matrix V and the secondarily beamformed second uplink measurement reference signal.

According to a fourth aspect, an embodiment of the present invention provides a network-side device, where the network-side device includes a transceiver and a processor.

The transceiver is configured to receive an uplink measurement reference signal sent by user equipment, where the uplink measurement reference signal carries downlink interference information of a downlink channel of the network-side device.

The processor is configured to perform downlink interference estimation on the uplink measurement reference signal, to obtain the downlink interference information.

In one embodiment, the uplink measurement reference signal received by the transceiver of the network-side device includes a first uplink measurement reference signal and a first uplink measurement reference signal beamformed by using the downlink interference information.

That the processor of the network device performs downlink interference estimation on the uplink measurement reference signal, to obtain interference information of the downlink channel includes performing channel estimation on the first uplink measurement reference signal, to obtain an uplink channel matrix H; then, performing channel estimation on the first uplink measurement reference signal beamformed by using the downlink interference information, to obtain a product H*I of the uplink channel matrix H and the downlink interference information I; and obtaining the downlink interference information based on the uplink channel matrix H and the product H*I.

In one embodiment, the transceiver of the network-side device is further configured to: before receiving the uplink measurement reference signal sent by the user equipment, send an instruction message to the user equipment, where the instruction message is used to instruct the user equipment to send the downlink interference information to the network-side device.

In one embodiment, the uplink measurement reference signal received by the transceiver of the network-side device includes a second uplink measurement reference signal beamformed by using a beamforming matrix V and a second uplink measurement reference signal obtained by beamforming, for the second time by using the downlink interference information, the second uplink measurement reference signal beamformed by using the beamforming matrix V; and that the processor of the network-side device performs downlink interference estimation on the uplink measurement reference signal, to obtain interference information of the downlink channel includes:

performing channel estimation on the second uplink measurement reference signal beamformed by using the beamforming matrix V, to obtain a product H*V of an uplink channel matrix H and the beamforming matrix V; then, performing channel estimation on the secondarily beamformed second uplink measurement reference signal, to obtain a product of the uplink channel matrix H, the beamforming matrix V, and the downlink interference information; and obtaining the downlink interference information based on H*V and a product of H*V and the downlink interference information.

According to a fifth aspect, an embodiment of the present invention provides a system for transmitting an uplink measurement reference signal, where the system includes the user equipment according to the third aspect and the network-side device according to the fourth aspect.

In the embodiments described in all the foregoing aspects, the instruction message sent by the network-side device may be used to instruct the user equipment to send, simultaneously or together to the network-side device, the first uplink measurement reference signal and the first uplink measurement reference signal beamformed by using the downlink interference information.

The instruction message sent by the network-side device may be used to instruct the user equipment to send, simultaneously or together to the network-side device, the second uplink measurement reference signal beamformed by using the beamforming matrix V and the second uplink measurement reference signal secondarily beamformed by using the downlink interference information. The instruction message may be uplink measurement reference signal scheduling signaling.

