CN108365937B

CN108365937B - Transmission method, transmission system, base station and terminal of reference signal

Info

Publication number: CN108365937B
Application number: CN201710062830.0A
Authority: CN
Inventors: 王爱玲; 王森; 潘成康; 左君; 徐国珍
Original assignee: China Mobile Communications Group Co Ltd; China Mobile Communications Ltd Research Institute
Current assignee: China Mobile Communications Group Co Ltd; China Mobile Communications Ltd Research Institute
Priority date: 2017-01-26
Filing date: 2017-01-26
Publication date: 2020-05-15
Anticipated expiration: 2037-01-26
Also published as: CN108365937A; WO2018137591A1

Abstract

The invention provides a transmission method, a transmission system, a base station and a terminal of a reference signal. The invention realizes the transmission of the hybrid broadband SRS and the sub-band SRS and improves the SRS transmission flexibility. In the invention, the transmission period of the broadband SRS can be increased to reduce the reference signal overhead, and the bandwidth configuration and transmission of the sub-band SRS are determined by the historical CSI information estimated by the base station in combination with the broadband SRS and the CQI reported by the sub-band, so that the bandwidth configuration and transmission can be flexibly configured according to the service state of the terminal, a plurality of sub-bands do not need to be sent on a plurality of symbols in a frequency hopping mode to cover the full frequency band, and the resource utilization rate can be improved. In addition, the sub-band SRS of the invention can be configured to be aperiodic transmission, the 'SRS reconfiguration indication' information can be indicated through DCI of a downlink control channel, and compared with an RRC signaling configuration mode in LTE, the indication mode using the DCI can reduce time delay and is more suitable for high-speed mobile scenes.

Description

Transmission method, transmission system, base station and terminal of reference signal

Technical Field

The invention relates to the technical field of mobile communication, in particular to a transmission method, a transmission system, a base station and a terminal of a reference signal.

Background

In a long term evolution time division duplex (LTE TDD) system, by using channel reciprocity, a base station end may obtain downlink channel state information through an uplink Sounding Reference Signal (SRS) transmitted by a user, and then generate a precoding matrix for downlink data transmission, and the like. The accuracy of channel estimation will seriously affect the system performance, for example, low Reference Signal (RS) allocation density will cause intolerable channel estimation error, high RS allocation density will cause too high Reference Signal overhead, and the resource waste is serious.

In the existing LTE system, the SRS time-frequency resource allocation density is mainly based on consideration of satisfying the estimation performance of the worst scenario, and SRS transmission is allocated on the last symbol of one subframe. Two transmission mechanisms of the SRS are provided, one is broadband transmission, namely, each user transmits an SRS signal on the whole system bandwidth; one is subband transmission, that is, each user transmits SRS signals only on some specific subbands, but in order to cover the full frequency band, the subband SRS needs to be transmitted in a frequency hopping manner on a plurality of symbols, which occupies a lot of resources. When multiple users multiplex the same time-frequency resource, each user can use a unique time-domain cyclic shift to assist the receiver in distinguishing different reference signals.

Transmission of SRS in LTE may be configured for periodic and aperiodic transmission. If the SRS is configured to be a periodic transmission mode, the user transmits the configured SRS once at intervals according to a given period; for the periodic SRS, there is also a terminal (UE) level configuration time interval for specifying whether the UE will not transmit after transmitting only one SRS or periodically transmit the SRS. The triggering of the aperiodic SRS is indicated by high-layer signaling or DCI (downlink control information).

For the existing SRS transmission scheme, when the number of multiplexed users increases to a certain extent, each SRS cannot be orthogonally distinguished by means of cyclic shift, which may cause severe interference and poor channel estimation performance. Especially in a 5G system, the cell user density is very high, and in limited resources, the same time-frequency resource may be needed to schedule more users at the same time, and meanwhile, the interference reduction and the channel estimation accuracy guarantee need to be considered. In addition, the periodic or aperiodic transmission of the conventional SRS is relatively fixed regardless of the transmission period or the content of the transmission, and it is difficult to dynamically satisfy the requirements of the configuration of the system parameters of 5G multi-scene, multi-service and diversity, so a dynamic and flexible SRS configuration scheme needs to be considered.

Disclosure of Invention

The technical problem to be solved in the embodiments of the present invention is to provide a transmission method, a transmission system, a base station, and a terminal for reference signals, so as to improve the flexibility of transmission of reference signals.

In order to solve the above technical problem, an embodiment of the present invention provides a method for transmitting a reference signal, which is applied to a base station side, and includes:

receiving a broadband Sounding Reference Signal (SRS) periodically transmitted by a terminal on the whole system frequency band, and estimating the channel quality of an uplink channel according to the received SRS;

sending a downlink reference signal to a terminal, and receiving feedback information of channel quality of a downlink channel sent by the terminal;

allocating an SRS sub-band for the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generating first SRS configuration information comprising the indication information of the SRS sub-band;

transmitting the first SRS configuration information to the terminal;

and receiving a sub-band SRS sent by the terminal on the SRS sub-band.

Preferably, in the above method, after the step of receiving the SRS transmitted by the terminal on the SRS subband, the method further includes:

and estimating the channel state information of the SRS subband according to the subband SRS sent by the terminal on the SRS subband.

Preferably, in the method, before the step of receiving the wideband sounding reference signal SRS periodically transmitted by the terminal over the entire system frequency band, the method further includes:

and sending the period configuration information of the sending period of the broadband SRS to a terminal.

Preferably, in the above method, after the step of generating the first SRS configuration information, the method further includes:

judging whether the first SRS configuration information is the same as second SRS configuration information of the terminal maintained locally: if the two are the same, ending the process; and if the first SRS configuration information is different from the second SRS configuration information, updating the second SRS configuration information of the locally maintained terminal to the first SRS configuration information, and entering the step of sending the first SRS configuration information to the terminal.

Preferably, in the above method, when the first SRS configuration information is different from second SRS configuration information of the terminal maintained locally, the method further includes:

and sending SRS reconfiguration indicating information to the terminal through the downlink control information DCI, wherein the SRS reconfiguration indicating information indicates that the terminal stops sending the sub-band SRS on the currently configured SRS sub-band.

Preferably, in the method, the first SRS configuration information is further transmitted to the terminal through a system message.

Preferably, in the above method, the SRS subband indication information includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence used in the SRS subband and a subband SRS transmission mode, where the transmission mode includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission.

Preferably, in the method, the indication information of the channel quality of the downlink channel includes indication information of the channel quality of each sub-band; the step of allocating an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel includes:

carrying out weighted summation on the channel quality of an uplink channel and the channel quality of a downlink channel corresponding to the same sub-band to obtain the channel quality evaluation of the sub-band;

and selecting the optimal sub-bands with the preset number according to the channel quality evaluation of each sub-band as the SRS sub-bands of the terminal.

Preferably, in the method, when the base station switches a beam used by the terminal, the step of transmitting the downlink reference signal to the terminal includes: and the base station sends a downlink reference signal to the terminal, and the downlink reference signal carries information of the wave beam adopted by the base station after switching.

Preferably, the method further comprises:

and extracting index information of the terminal aiming at the wave beam adopted by the base station, which is carried in the broadband SRS or the subband SRS, and determining the wave beam adopted by the terminal aiming at the base station according to the index information.

Preferably, the method further comprises:

and determining a beam corresponding to the SRS sequence according to a pre-established correspondence between the SRS sequence and the beam to obtain the beam adopted by the terminal for the base station.

The embodiment of the invention also provides a transmission method of the reference signal, which is applied to a terminal side and comprises the following steps:

periodically transmitting a broadband Sounding Reference Signal (SRS) on the whole system frequency band;

receiving a downlink reference signal sent by a base station, estimating the channel quality of a downlink channel according to the downlink reference signal, and sending feedback information of the channel quality of the downlink channel to the base station;

receiving first SRS configuration information which is sent by the base station and comprises indication information of SRS sub-bands;

a subband SRS transmitted on the SRS subband.

Preferably, before the step of periodically transmitting the wideband sounding reference signal SRS over the entire system frequency band, the method further includes:

and receiving the period configuration information of the transmission period of the broadband SRS transmitted by the base station, and determining the transmission period of the wide SRS.

Preferably, in the above method, when receiving an SRS reconfiguration instruction information sent by the base station through the downlink control information DCI, the SRS reconfiguration instruction information instructs the terminal to stop sending the subband SRS on the currently configured SRS subband, and the method further includes:

stopping subband SRS transmitted on the SRS subbands.

Preferably, in the method, the terminal further receives the first SRS configuration information sent by the base station through a system message.

Preferably, in the method, when the base station switches the beam used by the terminal, the downlink reference signal carries information of the beam used by the base station after the switching, and the terminal further obtains information of the beam used by the base station after the switching by analyzing the downlink reference signal.

Preferably, in the above method, when the terminal performs handover with respect to a beam used by the base station, the terminal further carries index information of the beam used by the terminal after the handover in the wideband SRS or the subband SRS.

Preferably, in the method, the terminal further determines an SRS sequence corresponding to a beam used by the base station according to a pre-established correspondence between the SRS sequence and the beam, and transmits the wideband SRS or the subband SRS using the determined SRS sequence.

An embodiment of the present invention further provides a base station, including:

a first receiving unit, configured to receive a wideband sounding reference signal SRS that is periodically sent by a terminal over a whole system frequency band, and estimate channel quality of an uplink channel according to the received wideband SRS;

a first sending unit, configured to send a downlink reference signal to a terminal, and receive feedback information of channel quality of a downlink channel sent by the terminal;

a configuration unit, configured to allocate an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generate first SRS configuration information including indication information of the SRS subband;

a second transmitting unit, configured to transmit the first SRS configuration information to the terminal;

and a second receiving unit, configured to receive a subband SRS sent by the terminal on the SRS subband.

Preferably, the base station further includes:

a first estimating unit, configured to estimate channel state information of the SRS subband according to a subband SRS sent by the terminal on the SRS subband.

Preferably, the base station further includes:

and a third transmitting unit, configured to transmit, to the terminal, periodic configuration information of a transmission period of a wideband Sounding Reference Signal (SRS) periodically transmitted by the terminal over the entire system frequency band, before receiving the SRS.

Preferably, the base station further includes:

a determining unit, configured to determine whether the first SRS configuration information is the same as second SRS configuration information of the locally maintained terminal: if the two are the same, no action is executed; and if the first SRS configuration information is different from the second SRS configuration information, updating second SRS configuration information of the locally maintained terminal to the first SRS configuration information, and triggering the second sending unit to send the first SRS configuration information.

Preferably, the base station further includes:

a fourth sending unit, configured to send, to the terminal through DCI when the first SRS configuration information is different from second SRS configuration information of the terminal that is locally maintained, SRS reconfiguration instruction information indicating that the terminal stops sending a subband SRS on a currently configured SRS subband, to the terminal.

Preferably, in the base station, the second transmitting unit further transmits the first SRS configuration information to the terminal through a system message.

Preferably, in the base station, the SRS subband indication information includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence used in the SRS subband and a subband SRS transmission method, where the transmission method includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission.

Preferably, in the base station, the information indicating the channel quality of the downlink channel includes information indicating the channel quality of each subband; the configuration unit is specifically configured to: carrying out weighted summation on the channel quality of an uplink channel and the channel quality of a downlink channel corresponding to the same sub-band to obtain the channel quality evaluation of the sub-band; and selecting the optimal sub-bands with the preset number according to the channel quality evaluation of each sub-band as the SRS sub-bands of the terminal.

Preferably, in the base station, the first sending unit is further configured to, when the base station performs handover on a beam used by the terminal, carry information of the beam used by the base station after the handover in the downlink reference signal.

Preferably, the base station further includes:

a first determining unit, configured to extract index information of a beam used by the terminal for the base station, where the index information is carried in the wideband SRS or the subband SRS, and determine the beam used by the terminal for the base station according to the index information.

Preferably, the base station further includes:

a second determining unit, configured to determine an SRS sequence used by the wideband SRS or the subband SRS, and determine, according to a correspondence between the SRS sequence and a beam that is established in advance, a beam corresponding to the SRS sequence, so as to obtain a beam used by the terminal for the base station.

An embodiment of the present invention further provides a terminal, including:

the device comprises a first sending unit, a second sending unit and a transmitting unit, wherein the first sending unit is used for periodically sending a broadband Sounding Reference Signal (SRS) on the whole system frequency band;

a first receiving unit, configured to receive a downlink reference signal sent by a base station, estimate channel quality of a downlink channel according to the downlink reference signal, and send feedback information of the channel quality of the downlink channel to the base station;

a second receiving unit, configured to receive first SRS configuration information including indication information of an SRS subband, sent by the base station;

and a second transmission unit, configured to transmit the subband SRS on the SRS subband.

Preferably, the terminal further includes:

and a third receiving unit, configured to receive cycle configuration information of a transmission cycle of the wideband SRS transmitted by the base station, and determine the transmission cycle of the wideband SRS.

Preferably, the terminal further includes:

and a transmission control unit, configured to, when receiving SRS reconfiguration instruction information sent by the base station through the downlink control information DCI, instruct the terminal to stop sending the subband SRS on the currently configured SRS subband, and control the second transmission unit to stop sending the subband SRS on the SRS subband.

Preferably, in the terminal, the second receiving unit is further configured to receive the first SRS configuration information transmitted by the base station through a system message.

Preferably, in the terminal, the SRS subband indication information includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence used in the SRS subband and a subband SRS transmission method, where the transmission method includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission.

Preferably, in the terminal, when the base station switches the beam used by the terminal, the downlink reference signal carries information of the beam used by the base station after the switching, and the first receiving unit is further configured to analyze and obtain the information of the beam used by the base station after the switching from the downlink reference signal.

Preferably, in the terminal, the first transmitting unit is further configured to, when the terminal performs handover on a beam used by a base station, carry, in a wideband SRS, index information of the beam used by the terminal after the handover; alternatively, the first and second electrodes may be,

the second sending unit is further configured to, when the terminal switches to a beam used by the base station, carry, in the sub-band SRS, index information of the beam used by the terminal after the switching.

Preferably, in the terminal, the first transmitting unit or the second transmitting unit is further configured to determine an SRS sequence corresponding to a beam used by the base station according to a pre-established correspondence between the SRS sequence and the beam, and transmit the wideband SRS or the subband SRS using the determined SRS sequence.

The embodiment of the invention also provides another reference signal transmission method, which comprises the following steps:

the terminal periodically transmits a broadband Sounding Reference Signal (SRS) on the whole system frequency band;

the base station receives the broadband SRS and estimates the channel quality of an uplink channel according to the received broadband SRS;

the base station sends a downlink reference signal to the terminal;

the terminal receives the downlink reference signal sent by the base station, estimates the channel quality of a downlink channel according to the downlink reference signal, and sends feedback information of the channel quality of the downlink channel to the base station;

the base station receives feedback information of the channel quality of a downlink channel sent by the terminal;

the base station allocates an SRS sub-band for the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, generates first SRS configuration information comprising the indication information of the SRS sub-band, and sends the first SRS configuration information to the terminal;

the terminal receives the first SRS configuration information sent by the base station, and sends a sub-band SRS on the SRS sub-band according to the first SRS configuration information;

and the base station receives the sub-band SRS sent by the terminal on the SRS sub-band.

The embodiment of the invention also provides a transmission system of the reference signal, which comprises a base station and at least one terminal, wherein:

the base station is used for receiving a broadband Sounding Reference Signal (SRS) periodically transmitted by the terminal on the whole system frequency band and estimating the channel quality of an uplink channel according to the received broadband SRS; sending a downlink reference signal to a terminal, and receiving feedback information of the channel quality of a downlink channel sent by the terminal; allocating an SRS sub-band for a terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generating first SRS configuration information comprising the indication information of the SRS sub-band; sending the first SRS configuration information to a terminal; receiving a sub-band SRS sent by a terminal on the SRS sub-band;

the terminal is used for periodically sending the broadband SRS on the whole system frequency band; receiving a downlink reference signal sent by a base station, estimating the channel quality of a downlink channel according to the downlink reference signal, and sending feedback information of the channel quality of the downlink channel to the base station; receiving first SRS configuration information which is sent by a base station and comprises indication information of an SRS subband; and a sub-band SRS transmitted on the SRS sub-band.

Compared with the prior art, the transmission method, the transmission system, the base station and the terminal for the reference signal provided by the embodiment of the invention realize the transmission of the hybrid broadband SRS and the subband SRS, and improve the SRS transmission flexibility. For example, the transmission period of the wideband SRS can be increased to reduce the overhead of the reference signal, and the bandwidth configuration and transmission of the subband SRS are determined by combining the historical CSI information estimated by the wideband SRS and the CQI reported by the subband, so that the bandwidth configuration and transmission can be flexibly configured according to the service state of the terminal, and a plurality of subbands do not need to be transmitted on a plurality of symbols in a frequency hopping manner to cover the full band, thereby improving the resource utilization rate. In addition, the sub-band SRS of the embodiment of the present invention may be configured for aperiodic transmission, and the "SRS reconfiguration indication" information thereof may be indicated by DCI of the downlink control channel, and compared with an RRC signaling configuration mode in LTE, the DCI indication mode may reduce the time delay and be more suitable for a high-speed mobile scenario. In addition, the embodiment of the invention can be suitable for a multi-antenna system considering a mixed architecture of a digital domain and an analog domain, and is a uniform SRS flexible configuration and transmission method.

Drawings

Fig. 1 is a schematic flowchart of a method for transmitting a reference signal according to an embodiment of the present invention;

fig. 2 is another schematic flow chart of a method for transmitting a reference signal according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a scenario in which a terminal side beam is not switched according to an embodiment of the present invention;

fig. 4 is a schematic view of a scenario in which a terminal-side beam is switched according to an embodiment of the present invention;

fig. 5 is an exemplary diagram illustrating an interaction procedure between a base station and a terminal according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating an exemplary configuration of a hybrid wideband SRS and sub-band SRS provided by an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a base station according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a terminal according to an embodiment of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments. In the following description, specific details such as specific configurations and components are provided only to help the full understanding of the embodiments of the present invention. Thus, it will be apparent to those skilled in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In various embodiments of the present invention, it should be understood that the sequence numbers of the following processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention. In addition, the terms "system" and "network" are often used interchangeably herein, and the terms "user" and "terminal" are often used interchangeably herein.

In the embodiment of the present invention, the Base Station may be a Macro Base Station (Macro Base Station), a micro Base Station (Pico Base Station), a Node B (the name of a 3G mobile Base Station), an enhanced Base Station (eNB), a Home enhanced Base Station (Femto eNB or Home eNode B or Home eNB or HeNB), a relay Station, an access point, an RRU (Remote Radio Unit), an RRH (Remote Radio Head), a network side Node in a 5G mobile communication system, such as a Central Unit (CU, Central Unit) and a Distributed Unit (DU, Distributed Unit), and the like. The terminal may be a mobile phone (or handset), or other device capable of sending or receiving wireless signals, including a User Equipment (UE), a Personal Digital Assistant (PDA), a wireless modem, a wireless communicator, a handheld device, a laptop computer, a cordless phone, a Wireless Local Loop (WLL) station, a CPE (Customer Premise Equipment) or mobile smart hotspot capable of converting mobile signals to WiFi signals, a smart appliance, or other device capable of autonomously communicating with a mobile communication network without human operation, etc.

As described in the background art, the periodic or aperiodic transmission of the existing SRS, whether the transmission period or the content of the transmission is relatively fixed, and it is difficult to dynamically satisfy the system parameter configuration requirements of 5G multi-scenario and multi-service and diversity.

In order to improve the flexibility of reference signal transmission, an embodiment of the present invention provides a method for transmitting a reference signal, which is applied to a base station side, and as shown in fig. 1, the method includes:

and step 11, receiving a wideband Sounding Reference Signal (SRS) periodically transmitted by the terminal over the entire system frequency band, and estimating the channel quality of the uplink channel according to the received wideband SRS.

Here, the Channel quality of the uplink Channel may be represented by Channel State Information (CSI), and the base station estimates the CSI of the uplink Channel according to the received wideband SRS. In the embodiment of the present invention, the terminal periodically transmits the wideband SRS, and the specific period configuration may be that before step 11, the base station transmits, to the terminal, period configuration information of a transmission period of the wideband SRS, so as to configure the period. Of course, the period may also be predetermined by both parties to reduce the configuration steps.

And step 12, sending a downlink reference signal to a terminal, and receiving feedback information of the channel quality of a downlink channel sent by the terminal.

Here, the base station transmits downlink reference information (e.g., CSI-RS) to the terminal, and the terminal measures a Channel according to the downlink reference information to obtain Channel Quality of the downlink Channel, such as Channel Quality Indicator (CQI) information. The terminal reports the channel quality information (such as CQI) estimated according to the downlink reference signal to the base station periodically/non-periodically through the uplink channel. Specifically, the reporting period may be configured as needed.

After step 12, the base station may determine a precoding matrix and a Modulation and Coding Scheme (MCS) according to the channel quality of the uplink channel obtained in the wideband SRS process and the channel quality of the downlink channel fed back by the terminal, and may then transmit service data to the terminal, where the service flow may refer to the existing LTE system, and details are not repeated herein.

Step 13, allocating an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generating first SRS configuration information including the SRS subband indication information.

Here, the SRS subband is a partial frequency band in the system frequency band, and the embodiment of the present invention performs transmission of the SRS in the subband in addition to transmission of the wideband SRS. And the base station allocates the SRS sub-band for transmitting the sub-band SRS to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel. The SRS subband indication information includes a frequency domain position (e.g., a start/stop position in the entire system band) and a bandwidth size of the SRS subband, and the first SRS configuration information may further include cyclic shift information of an SRS sequence used in the SRS subband and a subband SRS transmission mode, where the transmission mode includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission. The cyclic shift information is obtained by multiplexing a plurality of users in the same resource block, and when the users use the same SRS sequence, configuring different cyclic shifts (i.e. performing code division multiplexing) for each user, so as to ensure orthogonality of SRS transmission of different users.

When the SRS subband is allocated to the terminal, the wideband SRS may be used to monitor the entire frequency band, that is, the base station may estimate and obtain uplink Channel State Information (CSI) of the entire frequency band through the wideband SRS, so as to allocate the subband accordingly. Considering that, when the transmission period configuration of the wideband SRS is large, the base station may not accurately determine which subband is configured to the user to transmit the subband SRS only through the uplink CSI, so that it may also need to jointly determine Channel Quality Information (CQI) reported after the terminal estimates downlink channel state information through a downlink reference signal (e.g., CSI-RS). The reporting form of the CQI performed by the terminal may be divided into wideband CQI reporting (i.e., an average value of multiple CQIs in the entire bandwidth) and sub-band CQI reporting (different CQI values are reported in different sub-bands). In the TDD system, because of channel reciprocity, the same frequency bands in uplink and downlink have consistent CQIs without considering interference, and because interference exists in normal conditions, a sub-band with the best channel quality can be jointly determined and selected according to the uplink CSI estimated by using the wideband SRS and the CQI reported by the user, and configured to the user for transmitting the sub-band SRS. As an implementation manner, the channel quality of the uplink channel and the channel quality of the downlink channel corresponding to the same sub-band are weighted and summed to obtain the channel quality evaluation of the sub-band; and then, selecting an optimal preset number of sub-bands as the SRS sub-bands of the terminal according to the channel quality evaluation of each sub-band. Here, when performing the weighted sum, the channel quality of the uplink channel and the channel quality of the downlink channel are generally calculated using the channel quality of the last uplink channel and the channel quality of the downlink channel.

Step 14, sending the first SRS configuration information to the terminal.

Here, the base station may transmit the first SRS configuration information to the terminal through a system message.

And step 15, receiving the sub-band SRS sent by the terminal on the SRS sub-band.

Here, in the above-mentioned step 15,

after step 15, the base station may further estimate the channel state information of the SRS subband according to the SRS transmitted by the terminal on the SRS subband.

Through the steps, the embodiment of the invention realizes a mixed transmission scheme of the broadband SRS and the subband SRS, and compared with the prior SRS transmission scheme of LTE, the embodiment of the invention can greatly improve the flexibility of SRS transmission. For example, the embodiment of the present invention may reduce the overhead of the reference signal by increasing the transmission period of the wideband SRS, and in addition, the bandwidth configuration and transmission of the subband SRS are determined by the base station in combination with the historical CSI information estimated by the wideband SRS and the CQI reported by the terminal, so that the subband may be flexibly configured according to the service state of the terminal, and it is not necessary to transmit multiple subbands to cover the full band on multiple symbols in a frequency hopping manner, which may improve the resource utilization rate.

In the embodiment of the present invention, in step 13 above, after the step of generating the first SRS configuration information, the base station may further determine whether the first SRS configuration information is the same as second SRS configuration information of the terminal locally maintained: if the two are the same, ending the process; if not, updating the second SRS configuration information of the terminal maintained locally to the first SRS configuration information, and proceeding to

steps

14 and 15 to send the first SRS configuration information to the terminal and wait for receiving the SRS of the sub-band sent by the terminal on the SRS sub-band.

Further, when the first SRS configuration Information is different from the second SRS configuration Information of the terminal maintained locally, the base station may further send, to the terminal, SRS reconfiguration indication Information through Downlink Control Information (DCI), where the SRS reconfiguration indication Information indicates that the terminal abandons the configuration of the SRS in the previous subband, and stops sending the SRS in the subband on the currently configured SRS subband. Specifically, the SRS reconfiguration indication information may define a new DCI format in the existing DCI, and one way is to indicate in idle bits of the existing DCI; another way is to define a new bit to indicate on the basis of the existing DCI bits. Compared with an RRC signaling configuration mode in LTE, the DCI indication mode can reduce time delay and is more suitable for high-speed mobile scenes.

At present, the processing of multiple antennas in a 4G system is only performed in a data domain, and a fixed mapping mode from an antenna element to a radio frequency channel is performed in an analog domain, which brings about very large cost overhead and algorithm processing complexity, especially in a high-frequency band such as a millimeter wave communication system. It has been determined on 3GPP RAN1#86 conference that a digital domain and analog domain hybrid architecture multi-antenna system is considered in the 5G new air interface system. Therefore, flexible configuration and transmission scheme of combining beams (beams) are considered when designing SRS transmission.

In the embodiment of the present invention, the base station may dynamically configure the terminal to perform subband SRS transmission according to the beam switching conditions of the base station and the terminal side. Based on a mixed architecture of digital and analog introduced into a 5G new air interface, the influence of beam transformation at a base station (eNB) and a terminal (UE) on SRS configuration is considered. The method of the embodiment of the invention can be used as a uniform transmission framework to flexibly configure the SRS.

For example, referring to fig. 2, the left part of fig. 2 shows a scenario in which beams (beams) at the base station (eNB) and the terminal (UE) are not switched during transmission, and this example can also be regarded as a case where only one fixed beam is present in the existing LTE system without considering analog end beams. The right part of fig. 3 shows a scenario that the Beam of the eNB is switched from Beam1 to Beam2 during transmission, and the Beam of the UE does not perform switching, at this time, because after the Beam of the eNB is switched, the eNB sends a downlink reference signal (CSI-RS) directly on the Beam2, and the CSI-RS can carry information of the Beam switching of the base station.

In step 12, when the base station switches the beam used by the terminal, the base station sends a downlink reference signal to the terminal, and the downlink reference signal carries information of the beam used by the base station after the switching.

Referring to fig. 3, the left part of fig. 3 shows a scenario in which beams (beams) at the base station (eNB) end are not switched during transmission, and beams of a terminal (UE) are switched from beams 1 to beams 2 during transmission. The right part of fig. 4 shows a scenario where the Beam at the base station (eNB) side is switched from Beam1 to Beam2 during transmission, and the Beam of the terminal (UE) is switched from Beam1 to Beam2 during transmission.

When the terminal switches the beam adopted by the base station, one implementation manner is as follows: the terminal further carries index information of the beam adopted by the terminal after switching in a broadband SRS or the sub-band SRS. In this case, in

step

11 or 15, the base station may extract index information of a beam used by the terminal for the base station, which is carried in the wideband SRS or the subband SRS, and determine the beam used by the terminal for the base station according to the index information. Another implementation manner is that the terminal further determines, according to a correspondence between a pre-established SRS sequence and a beam, an SRS sequence corresponding to a beam used by the base station, and transmits the wideband SRS or the subband SRS using the determined SRS sequence. In this way, in

step

11 or 15, the base station may determine an SRS sequence adopted by the wideband SRS or the subband SRS, and determine a beam corresponding to the SRS sequence according to a correspondence relationship between the SRS sequence and the beam, which is established in advance, to obtain a beam adopted by the terminal for the base station.

Referring to fig. 4, a method for transmitting a reference signal according to an embodiment of the present invention, when applied to a terminal side, includes:

step 41, the terminal periodically transmits the wideband SRS over the entire system frequency band.

Here, the terminal may perform transmission of the wideband SRS at a pre-configured period. In this case, before step 41, the terminal may receive the period arrangement information of the transmission period of the wideband SRS transmitted by the base station and may determine the transmission period of the wideband SRS.

And 42, the terminal receives a downlink reference signal sent by the base station, estimates the channel quality of a downlink channel according to the downlink reference signal, and sends feedback information of the channel quality of the downlink channel to the base station.

Here, the channel quality of the downlink channel may be represented by CQI, and the terminal may periodically or aperiodically transmit feedback information of the channel quality of the downlink channel to the base station.

Step 43, the terminal receives the first SRS configuration information including the SRS subband indication information sent by the base station.

Here, the SRS subband is a partial frequency band allocated by the base station to the terminal from the system frequency band. The terminal may receive, through a system message, the first SRS configuration information sent by the base station, where the SRS configuration information may include a frequency domain position and a bandwidth size of an SRS subband, and the first SRS configuration information may further include cyclic shift information of an SRS sequence adopted on the SRS subband, a subband SRS transmission method, and the like, where the transmission method includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission. The terminal receives the first SRS configuration information, and may update the locally configured SRS configuration information according to the first SRS configuration information, where the SRS configuration information may include indication information of an SRS subband, cyclic shift information of an SRS sequence adopted on the SRS subband, a subband SRS transmission mode, and other contents.

And step 44, the terminal sends the sub-band SRS on the SRS sub-band.

Through the steps, the embodiment of the invention realizes that the terminal flexibly sends the broadband SRS and the subband SRS.

In the embodiment of the present invention, if a terminal receives SRS reconfiguration indication information sent by a base station through Downlink Control Information (DCI), where the SRS reconfiguration indication information indicates that the terminal stops sending a subband SRS on a currently configured SRS subband, the terminal stops sending the subband SRS on the SRS subband, and in addition, the terminal may also delete locally configured SRS configuration information.

Similarly, in consideration of a multi-antenna system with a mixed architecture of a digital domain and an analog domain, SRS needs to be used to assist beam management, in the embodiment of the present invention, when a base station switches a beam used by the terminal, the base station carries information of the beam used by the base station after the switching in a downlink reference signal sent to the terminal. At this time, the terminal further obtains information of the beam used by the base station after the handover by analyzing the downlink reference signal. When the terminal switches the beam used by the base station, one implementation manner is as follows: the terminal further carries index information of the beam adopted by the terminal after switching in the broadband SRS or the subband SRS, so that the base station can extract the index information of the beam adopted by the terminal for the base station, which is carried in the broadband SRS or the subband SRS, and determine the beam adopted by the terminal for the base station according to the index information. Another implementation manner is that the terminal further determines, according to a correspondence between a pre-established SRS sequence and a beam, an SRS sequence corresponding to a beam used by the base station, and transmits the wideband SRS or the subband SRS using the determined SRS sequence. In this way, the base station may determine an SRS sequence adopted by the wideband SRS or the subband SRS, and determine a beam corresponding to the SRS sequence according to a pre-established correspondence between the SRS sequence and the beam, so as to obtain a beam adopted by the terminal for the base station.

The transmission method of the reference signal according to the embodiment of the present invention is described above from the base station and the terminal side, respectively. From the perspective of interaction between a base station and a terminal, a transmission method in an embodiment of the present invention includes:

a, a terminal periodically sends a broadband Sounding Reference Signal (SRS) on the whole system frequency band;

b, the base station receives the broadband SRS and estimates the channel quality of an uplink channel according to the received broadband SRS;

step c, the base station sends a downlink reference signal to the terminal;

step d, the terminal receives the downlink reference signal sent by the base station, estimates the channel quality of the downlink channel according to the downlink reference signal, and sends the feedback information of the channel quality of the downlink channel to the base station;

step e, the base station receives feedback information of the channel quality of the downlink channel sent by the terminal;

step f, the base station allocates an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, generates first SRS configuration information including the indication information of the SRS subband, and sends the first SRS configuration information to the terminal;

step g, the terminal receives the first SRS configuration information sent by the base station, and sends a sub-band SRS on the SRS sub-band according to the first SRS configuration information;

and h, the base station receives the sub-band SRS sent by the terminal on the SRS sub-band.

An example of an interaction procedure between a base station and a terminal in the embodiment of the present invention is described below with reference to fig. 5:

in step 51, the base station (eNB) transmits wideband SRS pre-configuration information to the terminal (UE), where the pre-configuration information includes parameters such as a transmission period of the wideband SRS and may further include information indicating an SRS sequence.

Step 52, the terminal transmits the wideband SRS over the entire system band.

In step 53, the base station estimates the CSI based on the received SRS.

Step 54, the base station sends a downlink reference signal, such as CSI-RS.

And step 55, the terminal performs channel estimation according to the received downlink reference signal to obtain the CQI of each sub-band.

Step 56, the terminal periodically or non-periodically sends the CQI of each sub-band to the base station.

In step 57, the eNB allocates the SRS subband according to the CSI estimated last time and the CQI reported last time by the UE, and the specific allocation manner may refer to the foregoing description.

Step 58, the base station sends the sub-band SRS configuration information to the terminal, where the sub-band SRS configuration information may carry the bandwidth size of the SRS sub-band, the frequency band position, the SRS sequence, the cyclic shift information, and the indication of whether to send periodically.

And step 59, the terminal transmits SRS on the allocated SRS subband, and the base station receives SRS from the SRS subband.

Fig. 6 is a diagram illustrating an exemplary configuration of a hybrid wideband SRS and a subband SRS to which the transmission method according to the embodiment of the present invention is applied. In fig. 6, the wideband SRS 61 is configured in a periodic transmission mode, mainly used to monitor the entire transmission bandwidth, and its period is flexibly configurable. For different beams, the eNB may configure different sub-band SRSs, such as the sub-band SRS 62 and the sub-band SRS 63, and the specific frequency domain position of the sub-band may be selected according to the wideband SRS monitoring result and the CQI reported by the UE. The subband SRS in fig. 6 is transmitted non-periodically. If the wideband SRS and the subband SRS are transmitted in a time domain in a collision manner, that is, if the wideband SRS and the subband SRS are configured in the same subframe transmission period and aperiodic SRS, only the UE is configured to transmit the subband (aperiodic) SRS.

Based on the reference signal transmission method provided by the above embodiment, the embodiment of the invention also provides a system and a device for realizing the above method.

The embodiment of the invention provides a transmission system of reference signals, which comprises a base station and at least one terminal, and of course, the transmission system can also comprise a device unit at the core network side. Wherein:

the base station is used for receiving a broadband Sounding Reference Signal (SRS) periodically transmitted by the terminal on the whole system frequency band and estimating the channel quality of an uplink channel according to the received broadband SRS; sending a downlink reference signal to a terminal, and receiving feedback information of the channel quality of a downlink channel sent by the terminal; allocating an SRS sub-band for a terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generating first SRS configuration information comprising the indication information of the SRS sub-band; sending the first SRS configuration information to a terminal; and receiving the sub-band SRS sent by the terminal on the SRS sub-band.

Specifically, referring to fig. 7, an embodiment of the present invention provides a base station, including:

the first receiving unit 71 is configured to receive a wideband sounding reference signal SRS periodically transmitted by the terminal over the entire system frequency band, and estimate channel quality of an uplink channel according to the received wideband SRS.

A first sending unit 72, configured to send a downlink reference signal to a terminal, and receive feedback information of channel quality of a downlink channel sent by the terminal.

A configuration unit 73, configured to allocate an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generate first SRS configuration information including indication information of the SRS subband.

A second sending unit 74, configured to send the first SRS configuration information to the terminal.

A second receiving unit 75, configured to receive a subband SRS sent by the terminal on the SRS subband.

Here, the base station may further include:

Here, the SRS subband is a partial band in the system band.

The base station may further include:

Here, the base station may further include:

Here, the second transmitting unit further transmits the first SRS configuration information to the terminal through a system message.

Here, the SRS subband indication information includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence used in the SRS subband and a subband SRS transmission scheme, where the transmission scheme includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission.

Here, the information indicating the channel quality of the downlink channel includes information indicating the channel quality of each subband; the configuration unit is specifically configured to: carrying out weighted summation on the channel quality of an uplink channel and the channel quality of a downlink channel corresponding to the same sub-band to obtain the channel quality evaluation of the sub-band; and selecting the optimal sub-bands with the preset number according to the channel quality evaluation of each sub-band as the SRS sub-bands of the terminal.

Here, the first sending unit is further configured to, when a base station performs handover on a beam used by the terminal, carry information of the beam used by the base station after the handover in the downlink reference signal.

Here, the base station may further include:

Specifically, referring to fig. 8, an embodiment of the present invention further provides a terminal, including:

a first transmitting unit 81, configured to periodically transmit a wideband sounding reference signal SRS over the entire system frequency band.

A first receiving unit 82, configured to receive a downlink reference signal sent by a base station, estimate channel quality of a downlink channel according to the downlink reference signal, and send feedback information of the channel quality of the downlink channel to the base station.

A second receiving unit 83, configured to receive the first SRS configuration information including the SRS subband indication information transmitted by the base station.

A second transmitting unit 84, configured to transmit the subband SRS on the SRS subband.

Here, the terminal further includes:

Here, the SRS subband is a partial frequency band allocated by the base station to the terminal from the system frequency band.

The above terminal further includes:

Here, in the terminal, the second receiving unit is further configured to receive the first SRS configuration information transmitted by the base station through a system message.

Here, in the terminal, the SRS subband indication information includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence used in the SRS subband and a subband SRS transmission scheme, where the transmission scheme includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission.

Here, in the above terminal, when the base station performs handover on the beam used by the terminal, the downlink reference signal carries information of the beam used by the base station after the handover, and the first receiving unit is further configured to analyze and obtain the information of the beam used by the base station after the handover from the downlink reference signal.

Here, in the terminal, the first transmitting unit is further configured to, when the terminal performs a handover with respect to a beam used by a base station, carry, in a wideband SRS, index information of the beam used by the terminal after the handover; alternatively, the first and second electrodes may be,

Here, in the terminal, the first transmitting unit or the second transmitting unit is further configured to determine an SRS sequence corresponding to a beam used by the base station according to a pre-established correspondence between SRS sequences and beams, and transmit the wideband SRS or the subband SRS using the determined SRS sequence.

In summary, the transmission method, the transmission system, the base station and the terminal for the reference signal according to the embodiments of the present invention realize the transmission of the hybrid wideband SRS and the subband SRS, and improve the SRS transmission flexibility. For example, the transmission period of the wideband SRS can be increased to reduce the overhead of the reference signal, and the bandwidth configuration and transmission of the subband SRS are determined by combining the historical CSI information estimated by the wideband SRS and the CQI reported by the subband, so that the bandwidth configuration and transmission can be flexibly configured according to the service state of the terminal, and a plurality of subbands do not need to be transmitted on a plurality of symbols in a frequency hopping manner to cover the full band, thereby improving the resource utilization rate. In addition, the sub-band SRS of the embodiment of the present invention may be configured for aperiodic transmission, and the "SRS reconfiguration indication" information thereof may be indicated by DCI of the downlink control channel, and compared with an RRC signaling configuration mode in LTE, the DCI indication mode may reduce the time delay and be more suitable for a high-speed mobile scenario. In addition, the embodiment of the invention can be suitable for a multi-antenna system considering a mixed architecture of a digital domain and an analog domain, and is a uniform SRS flexible configuration and transmission method.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A transmission method of reference signals is applied to a base station side, and is characterized by comprising the following steps:

according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, allocating an SRS sub-band for the terminal, and generating first SRS configuration information including indication information of the SRS sub-band, wherein the SRS sub-band is a partial frequency band in a system frequency band, the indication information of the SRS sub-band includes a frequency domain position and a bandwidth size of the SRS sub-band, and the first SRS configuration information further includes cyclic shift information of an SRS sequence adopted on the SRS sub-band and a sub-band SRS transmission mode;

transmitting the first SRS configuration information to the terminal;

and receiving a sub-band SRS sent by the terminal on the SRS sub-band.

2. The method of claim 1, further comprising, after the step of receiving the SRS transmitted by the terminal on the SRS subband:

3. The method of claim 1, wherein before the step of receiving the wideband Sounding Reference Signal (SRS) periodically transmitted by the terminal over the entire system frequency band, the method further comprises:

4. The method of claim 1, further comprising, after the step of generating the first SRS configuration information:

5. The method of claim 4, wherein when the first SRS configuration information is different from second SRS configuration information of the terminal maintained locally, the method further comprises:

6. The method of claim 1, wherein the first SRS configuration information is further transmitted to the terminal via a system message.

7. The method according to claim 1, wherein the transmission pattern includes a transmission period at the time of periodic transmission and a transmission timing at the time of aperiodic transmission.

8. The method of claim 1, wherein the information indicative of the channel quality of the downlink channel includes information indicative of the channel quality of each sub-band; the step of allocating an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel includes:

9. The method of claim 1, wherein the step of transmitting the downlink reference signal to the terminal when the base station switches for the beam used by the terminal comprises: and the base station sends a downlink reference signal to the terminal, and the downlink reference signal carries information of the wave beam adopted by the base station after switching.

10. The method of claim 1, further comprising:

11. The method of claim 1, further comprising:

12. A transmission method of reference signals is applied to a terminal side, and is characterized by comprising the following steps:

receiving first SRS configuration information which is sent by the base station and comprises indication information of an SRS subband, wherein the SRS subband is a partial frequency band in a system frequency band, the indication information of the SRS subband comprises a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information also comprises cyclic shift information of an SRS sequence adopted on the SRS subband and a subband SRS sending mode;

a subband SRS transmitted on the SRS subband.

13. The method of claim 12, wherein before the step of periodically transmitting the wideband Sounding Reference Signal (SRS) over the entire system frequency band, further comprising:

14. The method of claim 12, wherein when receiving an SRS reconfiguration indicator sent by a base station via downlink control information DCI, the SRS reconfiguration indicator indicates that the terminal stops sending subband SRSs on a currently configured SRS subband, the method further comprising:

stopping subband SRS transmitted on the SRS subbands.

15. The method of claim 12, wherein the terminal further receives the first SRS configuration information transmitted by a base station through a system message.

16. The method according to claim 12, wherein the transmission pattern includes a transmission period at the time of periodic transmission and a transmission timing at the time of aperiodic transmission.

17. The method of claim 12, wherein when a base station performs handover on a beam used by the terminal, the downlink reference signal carries information of the beam used by the base station after the handover, and the terminal further obtains information of the beam used by the base station after the handover by parsing from the downlink reference signal.

18. The method of claim 12,

when the terminal switches the beam adopted by the base station, the terminal further carries index information of the beam adopted by the terminal after switching in the broadband SRS or the subband SRS.

19. The method of claim 12,

the terminal further determines an SRS sequence corresponding to the beam adopted by the base station according to the pre-established corresponding relation between the SRS sequence and the beam, and transmits the broadband SRS or the subband SRS by adopting the determined SRS sequence.

20. A base station, comprising:

a configuration unit, configured to allocate an SRS subband to the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generate first SRS configuration information including indication information of the SRS subband, where the SRS subband is a partial frequency band in a system frequency band, the indication information of the SRS subband includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence adopted on the SRS subband and a subband SRS transmission mode;

21. The base station of claim 20, further comprising:

22. The base station of claim 20, further comprising:

23. The base station of claim 20, further comprising:

24. The base station of claim 23, further comprising:

25. The base station of claim 20, wherein the second transmitting unit further transmits the first SRS configuration information to the terminal through a system message.

26. The base station of claim 20, wherein the transmission pattern includes a transmission period in the case of periodic transmission and a transmission time in the case of aperiodic transmission.

27. The base station of claim 20, wherein the information indicative of the channel quality of the downlink channel includes information indicative of the channel quality of each sub-band; the configuration unit is specifically configured to: carrying out weighted summation on the channel quality of an uplink channel and the channel quality of a downlink channel corresponding to the same sub-band to obtain the channel quality evaluation of the sub-band; and selecting the optimal sub-bands with the preset number according to the channel quality evaluation of each sub-band as the SRS sub-bands of the terminal.

28. The base station of claim 20,

the first sending unit is further configured to, when the base station switches the beam used by the terminal, carry information of the beam used by the base station after the switching in the downlink reference signal.

29. The base station of claim 20, further comprising:

30. The base station of claim 20, further comprising:

31. A terminal, comprising:

a second receiving unit, configured to receive first SRS configuration information that includes indication information of an SRS subband and is sent by the base station, where the SRS subband is a partial frequency band in a system frequency band, the indication information of the SRS subband includes a frequency domain position and a bandwidth size of the SRS subband, and the first SRS configuration information further includes cyclic shift information of an SRS sequence adopted on the SRS subband and a subband SRS sending manner;

32. The terminal of claim 31, further comprising:

33. The terminal of claim 31, further comprising:

34. The terminal of claim 31, wherein the second receiving unit is further configured to receive the first SRS configuration information sent by a base station through a system message.

35. The terminal according to claim 31, wherein the transmission pattern includes a transmission period at the time of periodic transmission and a transmission time at the time of aperiodic transmission.

36. The terminal of claim 31, wherein when a base station performs a handover with respect to a beam used by the terminal, the downlink reference signal carries information of the beam used by the base station after the handover, and the first receiving unit is further configured to obtain information of the beam used by the base station after the handover by parsing from the downlink reference signal.

37. The terminal of claim 31,

the first sending unit is further configured to, when the terminal switches to a beam used by a base station, carry, in a wideband SRS, index information of the beam used by the terminal after the switching; alternatively, the first and second electrodes may be,

38. The terminal of claim 31,

the first transmitting unit or the second transmitting unit is further configured to determine, according to a correspondence between a pre-established SRS sequence and a beam, an SRS sequence corresponding to a beam employed by the base station, and transmit the wideband SRS or the subband SRS using the determined SRS sequence.

39. A method for transmitting a reference signal, comprising:

the base station sends a downlink reference signal to the terminal;

the base station allocates an SRS sub-band for the terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, generates first SRS configuration information comprising indication information of the SRS sub-band, and transmits the first SRS configuration information to the terminal, wherein the SRS sub-band is a partial frequency band in a system frequency band, the indication information of the SRS sub-band comprises the frequency domain position and the bandwidth size of the SRS sub-band, and the first SRS configuration information further comprises cyclic shift information of an SRS sequence adopted on the SRS sub-band and a sub-band SRS transmission mode;

40. A transmission system of reference signals, comprising a base station and at least one terminal, wherein:

the base station is used for receiving a broadband Sounding Reference Signal (SRS) periodically transmitted by the terminal on the whole system frequency band and estimating the channel quality of an uplink channel according to the received broadband SRS; sending a downlink reference signal to a terminal, and receiving feedback information of the channel quality of a downlink channel sent by the terminal; allocating an SRS sub-band for a terminal according to the channel quality of the uplink channel and/or the channel quality of the downlink channel, and generating first SRS configuration information comprising the indication information of the SRS sub-band; sending the first SRS configuration information to a terminal, wherein an SRS subband is a partial frequency band in a system frequency band, the indication information of the SRS subband comprises the frequency domain position and the bandwidth size of the SRS subband, and the first SRS configuration information also comprises the cyclic shift information of an SRS sequence adopted on the SRS subband and a subband SRS sending mode; receiving a sub-band SRS sent by a terminal on the SRS sub-band;