TECHNICAL FIELD

This application relates to the mobile communications field, and in particular, to a technology for obtaining a reference signal in a wireless communications system.

BACKGROUND

In a Long Term Evolution (LTE) network, a base station usually allocates a part of system bandwidth regions to a specific terminal device. That is, within a specific time, resources in a specific frequency region are allocated to the terminal device. In this case, if the base station preferentially allocates high-quality resources in the specific frequency region to the terminal device, so that service quality of the terminal device is better ensured, a reference signal may provide reference for the base station during resource scheduling in this process.

At a same time, reference points of a plurality of broadcast channels coexist in frequency division multiplexing mode. For a method for generating first sequences corresponding to the reference points of the broadcast channels, refer to a method for generating a user equipment (UE) specific reference signal in the LTE network. A resource of one control channel resource set overlaps that of another control channel resource set on an orthogonal frequency division multiplexing (OFDM) symbol, and first sequences on reference signal resources included in resource element groups (REGs) on overlapping time-frequency resources are different.

Because a plurality of control channel resource sets overlap each other on time-frequency resources, and initial values of different reference signal sequences are different, sizes of overlapping resources do not affect configuration modes of the reference signal sequences. Consequently, reference signal sequences mapped to the overlapping resources are different, orthogonal code division multiplexing of a plurality of reference signals on the overlapping resources cannot be implemented, and multi-user multiple-input multiple-output (MU-MIMO) transmission performance is limited.

SUMMARY

Embodiments of the present invention provide a method and an apparatus for obtaining a reference signal, and a system to improve MU-MIMO transmission performance.

According to a first aspect, an embodiment of this application provides a method for obtaining a reference signal. The method includes: obtaining, by a terminal device, position offset information; obtaining a first sequence based on the position offset information; and demodulating.

In a possible design, the method further includes: generating, by the terminal device, a reference signal sequence; and obtaining the first sequence from the reference signal sequence based on the position offset information, where the first sequence is a subset of the reference signal sequence.

In a possible design, the method further includes: receiving, by the terminal device, a master information block (MIB) sent by a network device, where the MIB includes indication information of a first relative position and indication information of a second relative position, the first relative position is a position of a reference point of a broadcast channel carrying the MIB, relative to a frequency domain reference point, and the second relative position is a relative position of the control channel resource set relative to the reference point of the broadcast channel; and determining the position offset information according to the first relative position indicated by the indication information of the first relative position and the second relative position indicated by the indication information of the second relative position.

According to this solution, when reference points of a plurality of broadcast channels are sent in different frequency domain positions, reference signals used by control channel resources configured for reference points of different broadcast channels are selected from a same sequence. In addition, even if a plurality of control channel resources overlap each other, a same sequences in an overlapping region, and further, resource reuse by a plurality of users, for example, orthogonal MU-MIMO, can be implemented in the overlapping resource region. In addition, the MIB includes the position offset information of the control channel resources. This is advantageous to forward compatibility, and can flexibly avoid interference from a signal sent by a neighboring cell on the control channel resources.

In a possible design, the method further includes: receiving, by the terminal device, a MIB sent by a network device, where the MIB includes indication information used to indicate a third relative position, and the third relative position is a position of a reference point of a broadcast channel carrying the MIB, relative to a frequency domain reference point; and the obtaining, by a terminal device, position offset information includes: determining, by the terminal device, the position offset information according to the third relative position indicated by the indication information of the third relative position and a fourth relative position, where the fourth relative position is a relative position of the control channel resource set relative to the reference point of the broadcast channel, and the fourth relative position is configured or preset.

According to this solution, when a plurality of broadcast channels are sent in different frequency domain positions, reference signals used by control channel resources configured for reference points of different broadcast channels are selected from a same sequence. In addition, even if a plurality of control channel resources overlap each other, same sequences are used in an overlapping region, and further, resource reuse by a plurality of users, for example, orthogonal MU-MIMO, can be implemented in the overlapping resource region.

In a possible design, the method further includes: receiving, by the terminal device, a master information block MIB, where the MIB includes indication information used to indicate eighth relative position information of the control channel resource set relative to a frequency domain reference point; and the obtaining, by a terminal device, position offset information includes: determining, by the terminal device, the position offset information according to the eighth relative position indicated by the indication information of the eighth relative position.

When a plurality of broadcast channels may be sent in different frequency domain positions, if this solution is used, a same frequency domain reference point may be referenced by the obtained first sequence. Therefore, a plurality of overlapping control channel resources can share a same reference signal sequence, and further, resource reuse by a plurality of users, for example, orthogonal MU-MIMO, can be implemented. In addition, relative position information of a control channel relative to a reference point of a broadcast channel and relative position information of the reference point of the broadcast channel relative to the frequency domain reference point can be jointly encoded for indicating. This improves coding efficiency and reduces indication signaling overheads.

In a possible design, the method further includes: receiving, by the terminal device, configuration information of a bandwidth, where the bandwidth is a part of a system bandwidth, the configuration information includes indication information of a fifth relative position, and the fifth relative position is a relative position of a bandwidth comprising the control channel resource set relative to a frequency domain reference point; and the obtaining, by a terminal device, position offset information includes: determining, by the terminal device, the position offset information according to the fifth relative position indicated by the indication information of the fifth relative position.

According to this solution, the configuration information of the bandwidth may be carried in remaining minimum system information (RMSI) other than a MIB. Therefore, indication signaling overheads of the MIB are reduced. In addition, the RMSI may carry more bit information, and further, an offset of a bandwidth in frequency domain may be more flexible, that is, an offset granularity in frequency domain may be smaller. Therefore, the offset of the bandwidth is more flexible, and resource utilization can be improved.

In a possible design, the method further includes: receiving, by the terminal device, configuration information of a bandwidth, where the bandwidth is a part of a system bandwidth, the configuration information includes indication information of a sixth relative position and indication information of a seventh relative position, the sixth relative position is a relative position of a bandwidth comprising the control channel resource set relative to a reference point of a broadcast channel carrying a MIB, and the seventh relative position is a position of the reference point of the broadcast channel carrying the MIB, relative to a frequency domain reference point; and the obtaining, by a terminal device, position offset information includes: determining the position offset information according to the sixth relative position indicated by the indication information of the sixth relative position and the seventh relative position indicated by the indication information of the seventh relative position.

According to this solution, the configuration information of the bandwidth may be carried in RMSI other than a MIB. Therefore, indication signaling overheads of the MIB are reduced. In addition, system information (the RMSI) may carry more bit information, and further, an offset of a bandwidth in frequency domain may be more flexible, that is, an offset granularity in frequency domain may be smaller. Therefore, the offset of the bandwidth is more flexible, and resource utilization can be improved.

In a possible design, the obtaining, by a terminal device, position offset information includes: receiving, by the terminal device, configuration information of the control channel resource set, where the configuration information of the control channel resource set includes indication information used to indicate the position offset information, obtaining, by the terminal device, the position offset information according to the indication information used to indicate the position offset information.

According to this solution, when configuring time-frequency resources of the control channel resource set, a network device obtains an overlapping resource region on the time-frequency resources, and determines the position offset information according to the overlapping resource region, and when configuring the control channel resource set, configures position offset information of a first sequence used by a control channel reference signal, so that reference signal sequences of a plurality of control channels are the same in the overlapping region. Therefore, orthogonal reuse by a plurality of users, that is, orthogonal MU-MIMO, is enabled. In addition, non-orthogonal interference between sequences that is caused by a plurality of different sequences on a same reference signal resource can be reduced.

For example, the indication information used to indicate the position offset information includes indication information used to indicate a physical resource block number of the control channel resource set; and the obtaining, by a terminal device, position offset information includes: determining, by the terminal device, the position offset information according to the indication information used to indicate the physical resource block number.

According to this solution, all control channel resources use a same physical resource block number, and a reference point of the physical resource block number may be notified by a MIB or RMSI, and further, the terminal device obtains the unified physical resource block number in frequency domain according to a same frequency domain reference point. Therefore, first sequences determined for control channel resource sets including the same physical resource block number are the same, so that first sequences of control channel resource sets with overlapping resources are the same. Therefore, orthogonal reuse by a plurality of users, that is, orthogonal MU-MIMO, is enabled.

In a possible design, the method further includes: receiving, by the terminal device, a MIB sent by a network device, where the MIB includes indication information used to indicate an eleventh relative position of the control channel resource set relative to a reference point of a broadcast channel carrying the MIB; and obtaining, by the terminal device, the second sequence from the reference signal sequence according to the indication information, where the second sequence is a subset of the reference signal sequence. In the method, the MIB does not need to carry indication information of the frequency domain reference point. Therefore, indication signaling overheads of the MIB are reduced. In addition, the frequency domain reference point is indicated by RMSI occupying more resources. Therefore, bandwidth configurations are more flexible, fragments of the bandwidth in use are reduced, and spectrum utilization is improved. The second sequence is used for a reference signal included in a first control channel resource set configured by the MIB, and the first control channel resource set includes a common search space, and mainly carries control information for scheduling the RMSI. The foregoing first sequence is used for the control channel resource set configured by RRC, and the first control channel resource set includes a common search space and/or a user specific search space, and mainly carries control information for scheduling data.

According to a second aspect, an embodiment of this application provides a method for obtaining a reference signal. The method includes: obtaining, by a network device, position offset information; obtaining a first sequence based on the position offset information.

In a possible design, the method further includes: generating, by the network device, a reference signal sequence; and obtaining the first sequence from the reference signal sequence based on the position offset information, where the first sequence is a subset of the reference signal sequence.

In a possible design, the method further includes: sending, by the network device, a MIB to a terminal device, where the MIB includes indication information of a first relative position and indication information of a second relative position, the first relative position is a position of a reference point of a broadcast channel carrying the MIB, relative to a frequency domain reference point, the second relative position is a relative position of the control channel resource set relative to the reference point of the broadcast channel, and the indication information of the first relative position and the indication information of the second relative position are used to indicate the position offset information.

In a possible design, the method further includes: receiving, by the terminal device, a MIB sent by a network device, where the MIB includes indication information of a third relative position, the third relative position is a position of a reference point of a broadcast channel carrying the MIB, relative to a frequency domain reference point, the indication information of the third relative position is used with a fourth relative position to indicate the position offset information, the fourth relative position is a relative position of the control channel resource set relative to the reference point of the broadcast channel, and the fourth relative position is configured or preset.

In a possible design, the method further includes: sending, by the network device, a master information block MIB to a terminal device, where the MIB includes indication information used to indicate eighth relative position information of the control channel resource set relative to a frequency domain reference point, and the indication information of the eighth relative position information is used to indicate the position offset information.

In a possible design, the method further includes: sending, by the network device, configuration information of a bandwidth to a terminal device, where the bandwidth is a part of a system bandwidth, the configuration information includes indication information of a fifth relative position, the fifth relative position is a relative position of a bandwidth comprising the control channel resource set relative to a frequency domain reference point, and the indication information of the fifth relative position is used to indicate the position offset information.

In a possible design, the method further includes: sending, by the network device, configuration information of a bandwidth to a terminal device, where the bandwidth is a part of a system bandwidth, the configuration information includes indication information of a sixth relative position and indication information of a seventh relative position, the sixth relative position is a relative position of a bandwidth comprising the control channel resource set relative to a reference point frequency domain position of a broadcast channel carrying a MIB, the seventh relative position is a position of the reference point of the broadcast channel carrying the MIB, relative to a frequency domain reference point, and the indication information of the sixth relative position and the indication information of the seventh relative position are used to indicate the position offset information.

In a possible design, the method further includes: sending, by the network device, configuration information of the control channel resource set to a terminal device, where the configuration information of the control channel resource set includes indication information used to indicate the position offset information. The indication information used to indicate the position offset information includes indication information used to indicate a physical resource block number of the control channel resource set.

In a possible design, the method further includes: sending, by the network device, a master information block MIB, where the MIB includes indication information used to indicate an eleventh relative position of the control channel resource set relative to a reference point of a broadcast channel carrying the MIB.

According to a third aspect, an embodiment of this application provides an apparatus for obtaining a reference signal, where the apparatus has a function for implementing actions of the terminal device in the foregoing method designs. The function may be implemented by hardware, or may be implemented by corresponding software executed by hardware. The hardware or software includes one or more modules corresponding to the foregoing function.

In a possible design, a structure of the terminal device includes a processor, where the processor is configured to: obtain position offset information, and obtain a first sequence based on the position offset information.

According to a fourth aspect, an embodiment of this application provides an apparatus for obtaining a reference signal. The apparatus has a function for implementing actions of the network device in the foregoing method designs. The function may be implemented by hardware, or may be implemented by corresponding software executed by hardware. The hardware or software includes one or more modules corresponding to the foregoing function.

In a possible design, a structure of the apparatus includes a processor, where the processor is configured to support the network device in performing corresponding functions in the foregoing method. The network device may further include a memory. The memory is coupled with the processor. The memory stores a program instruction and data required by the network device.

In a possible design, in any method in the first to the fourth aspects, the configuration information of the control channel resource set includes at least one of a random access response (RAR) and radio resource control (RRC) signaling, and the control channel resource set includes a type-1 common search space (CSS) and/or a terminal specific search space (USS).

In any one of the first to the fourth aspects, the frequency domain reference point is a system carrier bandwidth boundary or a center frequency domain position, or is a candidate position of a channel raster, where the candidate position of the channel raster is a candidate subcarrier position within the system carrier bandwidth, and the candidate subcarrier position is a predefined position; and the reference point of the broadcast channel is a center frequency domain position or a boundary of a resource on which the reference point of the broadcast channel is located.

According to a fifth aspect, an embodiment of this application provides a method for obtaining a reference signal, where the method includes: obtaining, by a terminal device, an initial value for generating a first sequence or length information of a first sequence; generating the first sequence based on the initial value or the length information of the first sequence.

In a possible design, the method further includes: receiving, by the terminal device, a MIB, where the MIB includes indication information used to indicate a time-frequency resource occupied by the control channel resource set; and determining a length of the first sequence according to the indication information used to indicate the time-frequency resource occupied by the control channel resource set.

In a possible design, the obtaining, by a terminal device, an initial value for generating a first sequence includes: obtaining, by the terminal device, one or more of a synchronization signal, a broadcast channel scrambling sequence, a broadcast channel reference signal, or broadcast information that includes the initial value for generating the first sequence.

According to the solution provided by the fifth aspect, the MIB does not include indication information of a frequency domain reference point, and therefore, indication signaling overheads of the MIB can be reduced. Therefore, the terminal device cannot obtain a position relative to the frequency domain reference point, and can only directly generate a reference signal sequence, or truncate the first sequence from a center position of a reference signal sequence. Because a size of an initial access bandwidth is limited, it is less possible that control channel resource sets sent in different frequency bands in frequency domain overlap each other in frequency domain. Therefore, reuse by a plurality of users is impossible. However, a terminal device receiving RMSI can obtain the first sequence according to a reference point configured by the RMSI, and orthogonal reuse by a plurality of users, that is, MU-MIMO, can be implemented in an overlapping resource region between a plurality of control channel resource sets.

According to a sixth aspect, an embodiment of this application provides a method for obtaining a reference signal, where the method includes: obtaining, by a network device, an initial value for generating a first sequence or length information of a first sequence; generating the first sequence based on the initial value or the length information of the first sequence.

In a possible design, the method further includes: sending, by the network device, a MIB to a terminal device, where the MIB includes indication information used to indicate a time-frequency resource occupied by the control channel resource set.

In a possible design, the method further includes: sending, by the network device, one or more of a synchronization signal, a broadcast channel scrambling sequence, a broadcast channel reference signal, or broadcast information that includes the initial value for generating the first sequence to the terminal device.

According to a seventh aspect, an embodiment of this application provides an apparatus for obtaining a reference signal, where the apparatus has a function for implementing actions of the terminal device in the foregoing method designs. The function may be implemented by hardware, or may be implemented by corresponding software executed by hardware. The hardware or software includes one or more modules corresponding to the foregoing function. The module may be software and/or hardware.

In a possible design, the terminal device includes a processor, configured to: obtain an initial value for generating a first sequence or length information of the first sequence; generate the first sequence based on the initial value or the length information of a first sequence; and demodulate, by using the first sequence, a control channel signal carried in a control channel resource set, to obtain downlink control information.

According to an eighth aspect, an embodiment of this application provides an apparatus for obtaining a reference signal, where the apparatus has a function for implementing actions of the network device in the foregoing method designs. The function may be implemented by hardware, or may be implemented by corresponding software executed by hardware. The hardware or software includes one or more modules corresponding to the foregoing function.

In a possible design, a structure of the apparatus includes a processor and a transmitter, where the processor is configured to support a network device in performing corresponding functions in the foregoing method. The apparatus may further include a memory. The memory is coupled with the processor. The memory stores a program instruction and data required by the apparatus.

According to a ninth aspect, an embodiment of this application provides a computer readable storage medium, where the computer readable storage medium stores a computer software instruction used by a terminal device, and the instruction is used to execute the method designed in the first aspect.

According to a tenth aspect, an embodiment of this application provides a readable storage medium, where the computer readable storage medium stores an instruction of a network device, and the instruction is used to execute the program designed in the second aspect.

According to an eleventh aspect, an embodiment of this application provides a computer readable storage medium, where the computer readable storage medium stores an instruction of a terminal device, and the instruction is used to execute the program designed in the fifth aspect.

According to a twelfth aspect, an embodiment of this application provides a readable storage medium, where the computer readable storage medium stores an instruction of a network device, and the instruction is used to execute the program designed in the sixth aspect.

According to a thirteenth aspect, an embodiment of this application provides a communications apparatus, including: a memory, where the memory is configured to store computer executable program code; and a processor, where when the processor executes the instruction, the apparatus is configured to implement the method according to the first aspect.

According to a fourteenth aspect, an embodiment of this application provides a communications apparatus, including: a memory, where the memory is configured to store computer executable program code; and a processor, where when the processor executes the instruction, the apparatus is configured to implement the method according to the second aspect.

According to a fifteenth aspect, an embodiment of this application provides a communications apparatus, including: a memory, where the memory is configured to store computer executable program code; and a processor, where when the processor executes the instruction, the apparatus is configured to implement the method according to the fifth aspect.

According to a sixteenth aspect, an embodiment of this application provides a communications apparatus, including: a memory, configured to store computer executable program code; and a processor, where when the processor executes the instruction, the apparatus is configured to implement the method according to the sixth aspect.

