This application is a National Stage of International Application No. PCT/CN2017/070366, filed Jan. 06, 2017, which claims the benefit of Chinese Patent Application No. 201510752428.6, filed with the Chinese Patent Office on Nov. 06, 2015, and entitled “A method and apparatus for transmitting an SRS”, which are hereby incorporated by reference in their entireties.

FIELD

The present invention relates to the field of communications, and particularly to a method and apparatus for transmitting an SRS.

BACKGROUND

As the internet of things is emerging, a support of Machine Type Communication (MTC) in a Long Term Evolution (LTE) system has been increasingly valued. An MTC device (or an MTC terminal) may have a part of Machine to Machine (M2M) communication characteristics. e.g., low mobility, a small amount of data to be transmitted, insensitivity to a communication delay, extremely low power consumption as required, etc., where in order to lower the cost of the MTC terminal, a type of terminal supporting a radio frequency bandwidth of only 1.4 MHz in both the uplink and the downlink has been newly defined.

Since the MTC terminal can only operate in a limited bandwidth, several narrowbands may be defined for the MTC terminal in a system band, where there are a limited number of Physical Resource Blocks (PRBs) in each narrowband. Particularly there are six PRBs in each narrowband. There is uplink transmission and downlink transmission by the MTC terminal in only one of the narrowbands. When the transmitting terminal is to jump from one narrowband to another narrowband, some retuning period of time is required for a radio frequency element, etc., of the terminal to be retuned from the narrowband to the other.

A Sounding Reference Symbol (SRS) is transmitted in the last SC-FDMA symbol in an SRS sub-frame preconfigured in higher-layer signaling. For a TDD system, an SRS can be transmitted in one or two UpPTS symbols in a special sub-frame. A transmission bandwidth of an SRS in the frequency domain is preconfigured in the higher-layer signaling as an integer multiply of four PRBs. An SRS may or may not be transmitted in a system SRS bandwidth in a frequency hop mode as configured in the higher-layer signaling. When transmission of an SRS in the frequency hop mode is enabled, an SRS may be transmitted at a different frequency position selected in a different SRS sub-frame in a fixed frequency hop pattern.

An SRS can be transmitted in the same sub-frame as a Physical Uplink Control Channel (PUCCH)/Physical Uplink Shared Channel (PUSCH), where the last symbols of the PUCCH and the PUSCH are spared for transmitting an SRS instead of data. In a low-complexity MTC system, a frequency position where an SRS is transmitted, and a narrowband in which a PUCCH/PUSCH is transmitted can be determined separately, and when an SRS can be transmitted in a frequency hop mode, the SRS is also transmitted at a different frequency position in a different SRS sub-frame, so the frequency position where the SRS is transmitted may not overlap with the narrowband in which the PUCCH/PUSCH adjacent thereto is transmitted in the frequency domain; and there are so limited transmit and receive bandwidths of low-complexity MTC that signals cannot be transmitted and received at different narrowband positions at the same instance of time, and a retuning period of time is required between the different narrowbands to retune a radio frequency element to the different frequency positions, so the SRS transmission rule in the prior art may not be applicable to the low-complexity MTC system any longer.

SUMMARY

In view of this, embodiments of the invention provide a method and apparatus for transmitting an SRS.

An embodiment of the invention provides a method for transmitting an SRS, the method includes: deciding whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data, or according to whether adjacent narrowbands for transmitting data are same.

Optionally deciding whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data includes: in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data, and there are uplink data transmitted in the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel, and there are uplink data transmitted in the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel, and there are uplink data transmitted in the SRS sub-frame, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally deciding whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data includes: in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally if an uplink channel transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame is a Physical Random Access Channel (PRACH), then deciding whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data will include: in the SRS sub-frame, if the transmission frequency resources of an SRS do not overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a Timing Advance (TA) value corresponding to the SRS sub-frame is less than a retuning period of time, then deciding not to transmit an SRS in the SRS sub-frame; or in the SRS sub-frame, if the transmission frequency resources of an SRS partially overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a TA value corresponding to the SRS sub-frame is less than a retuning period of time, then deciding not to transmit an SRS in the SRS sub-frame; or in the SRS sub-frame, if the transmission frequency resources of an SRS partially overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a TA value corresponding to the SRS sub-frame is less than a retuning period of time, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally deciding whether to transmit an SRS, according to whether adjacent narrowbands for transmitting data are the same includes: if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in both of the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which does not overlap with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which partially overlaps with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame, and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which partially overlaps with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband in which there are uplink data transmitted, among the transmission frequency resources of an SRS.

Optionally deciding whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data includes: in a special sub-frame of a Time Division Duplex (TDD) system, if transmission frequency resources of an SRS in an Uplink Pilot Time Slot (UpPTS) do not overlap with a narrowband for transmitting downlink data in a Downlink Pilot Time Slot (DwPTS), then deciding not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS do not overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, then deciding not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, then deciding not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, then deciding not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting downlink data in the DwPTS, among the transmission frequency resources of an SRS; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, then deciding not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting downlink data in the DwPTS, among the transmission frequency resources of an SRS.

Optionally deciding whether to transmit an SRS, according to whether adjacent narrowbands for transmitting data are the same includes: if a narrowband for transmitting downlink data in a DwPTS of a special sub-frame of a TDD system is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the special sub-frame, then deciding not to transmit an SRS in an UpPTS of the special sub-frame; or if a narrowband for transmitting downlink data in a DwPTS of a special sub-frame of a TDD system is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the special sub-frame, and there are data transmitted in both of the DwPTS of the special sub-frame and the adjacent uplink sub-frame subsequent to the special sub-frame, then deciding not to transmit an SRS in an UpPTS of the special sub-frame.

Optionally the uplink data include data transmitted in one or more of following uplink channels: a PUCCH, a PUSCH, and a PRACH.

Optionally the downlink data include data transmitted in one or more of following downlink channels: a PDSCH an M-PDCCH, a PBCH, and a PMCH.

Optionally the SRS sub-frame is a sub-frame specific to a narrowband terminal, and the SRS sub-frame includes an UpPTS or a normal uplink sub-frame.

An embodiment of the invention provides an apparatus for transmitting an SRS, the apparatus includes: a determining unit configured to decide whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data, or whether adjacent narrowbands for transmitting data are the same.

Optionally the determining unit is configured: in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data, and there are uplink data transmitted in the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel, and there are uplink data transmitted in the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame, or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel, and there are uplink data transmitted in the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally the determining unit is configured: in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally the determining unit is configured: if an uplink channel transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame is a Physical Random Access Channel (PRACH), then: in the SRS sub-frame, if the transmission frequency resources of an SRS do not overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a Timing Advance (TA) value corresponding to the SRS sub-frame is less than a retuning period of time, to decide not to transmit an SRS in the SRS sub-frame; or in the SRS sub-frame, if the transmission frequency resources of an SRS partially overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a TA value corresponding to the SRS sub-frame is less than a retuning period of time, to decide not to transmit an SRS in the SRS sub-frame; or in the SRS sub-frame, if the transmission frequency resources of an SRS partially overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a TA value corresponding to the SRS sub-frame is less than a retuning period of time, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally the determining unit is configured: if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in both of the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which does not overlap with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame, and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which partially overlaps with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which partially overlaps with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband in which there are uplink data transmitted, among the transmission frequency resources of an SRS.

Optionally the determining unit is configured: in a special sub-frame of a Time Division Duplex (TDD) system, if transmission frequency resources of an SRS in an Uplink Pilot Time Slot (UpPTS) do not overlap with a narrowband for transmitting downlink data in a Downlink Pilot Time Slot (DwPTS), to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS do not overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting downlink data in the DwPTS, among the transmission frequency resources of an SRS; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting downlink data in the DwPTS, among the transmission frequency resources of an SRS.

Optionally the determining unit is configured: if a narrowband for transmitting downlink data in a DwPTS of a special sub-frame of a TDD system is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the special sub-frame, to decide not to transmit an SRS in an UpPTS of the special sub-frame; or if a narrowband for transmitting downlink data in a DwPTS of a special sub-frame of a TDD system is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the special sub-frame, and there are data transmitted in both of the DwPTS of the special sub-frame and the adjacent uplink sub-frame subsequent to the special sub-frame, to decide not to transmit an SRS in an UpPTS of the special sub-frame.

Optionally the uplink data include data transmitted in one or more of following uplink channels: a PUCCH, a PUSCH, and a PRACH.

Optionally the downlink data include data transmitted in one or more of following downlink channels: a PDSCH, an M-PDCCH, a PBCH and a PMCH.

Optionally the SRS sub-frame is a sub-frame specific to a narrowband terminal, and the SRS sub-frame includes an UpPTS or a normal uplink sub-frame.

An embodiment of the invention provides an apparatus for transmitting an SRS, the apparatus including a processor, a memory, and a transceiver; the processor is configured to read and execute program in the memory: to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data, or whether adjacent narrowbands for transmitting data are same; and the transceiver is configured to be controlled by the processor to transmit and receive data.

Optionally the processor is configured: in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data, and there are uplink data transmitted in the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel, and there are uplink data transmitted in the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel, and there are uplink data transmitted in the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally the processor is configured: in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS do not overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or in an SRS sub-frame, if transmission frequency resources of an SRS partially overlap with a narrowband for transmitting an uplink channel in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally the processor is configured: if an uplink channel transmitted in the adjacent uplink sub-frame subsequent to the SRS sub-frame is a Physical Random Access Channel (PRACH), then: in the SRS sub-frame, if the transmission frequency resources of an SRS do not overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a Timing Advance (TA) value corresponding to the SRS sub-frame is less than a retuning period of time, to decide not to transmit an SRS in the SRS sub-frame; or in the SRS sub-frame, if the transmission frequency resources of an SRS partially overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a TA value corresponding to the SRS sub-frame is less than a retuning period of time, to decide not to transmit an SRS in the SRS sub-frame; or in the SRS sub-frame, if the transmission frequency resources of an SRS partially overlap with the narrowband for transmitting a PRACH in the adjacent uplink sub-frame subsequent to the SRS sub-frame, and a TA value corresponding to the SRS sub-frame is less than a retuning period of time, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting uplink data, among the transmission frequency resources of an SRS.

Optionally the processor is configured: if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in both of the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which does not overlap with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame, and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which partially overlaps with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS in the SRS sub-frame; or if a narrowband for transmitting uplink data in the SRS sub-frame is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the SRS sub-frame, and there are uplink data transmitted in a narrowband, which partially overlaps with transmission frequency resources of an SRS, among the narrowband for transmitting uplink data in the SRS sub-frame and the narrowband for transmitting uplink data in the adjacent uplink sub-frame subsequent to the SRS sub-frame, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband in which there are uplink data transmitted, among the transmission frequency resources of an SRS.

Optionally the processor is configured: in a special sub-frame of a Time Division Duplex (TDD) system, if transmission frequency resources of an SRS in an Uplink Pilot Time Slot (UpPTS) do not overlap with a narrowband for transmitting downlink data in a Downlink Pilot Time Slot (DwPTS), to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS do not overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, to decide not to transmit an SRS in the UpPTS of the special sub-frame; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting downlink data in the DwPTS, among the transmission frequency resources of an SRS; or in a special sub-frame of a TDD system, if transmission frequency resources of an SRS in an UpPTS partially overlap with a narrowband for transmitting downlink data in a DwPTS, and there are downlink data transmitted in the DwPTS, to decide not to transmit an SRS over frequency resources, which do not overlap with the narrowband for transmitting downlink data in the DwPTS, among the transmission frequency resources of an SRS.

Optionally the processor is configured: if a narrowband for transmitting downlink data in a DwPTS of a special sub-frame of a TDD system is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the special sub-frame, to decide not to transmit an SRS in an UpPTS of the special sub-frame; or if a narrowband for transmitting downlink data in a DwPTS of a special sub-frame of a TDD system is different from a narrowband for transmitting uplink data in an adjacent uplink sub-frame subsequent to the special sub-frame, and there are data transmitted in both of the DwPTS of the special sub-frame and the adjacent uplink sub-frame subsequent to the special sub-frame, to decide not to transmit an SRS in an UpPTS of the special sub-frame.

Optionally the uplink data include data transmitted in one or more of following uplink channels: a PUCCH, a PUSCH, and a PRACH.

Optionally the downlink data include data transmitted in one or more of following downlink channels: a PDSCH, an M-PDCCH, a PBCH, and a PMCH.

Optionally the SRS sub-frame is a sub-frame specific to a narrowband terminal, and the SRS sub-frame includes an UpPTS or a normal uplink sub-frame.

In the embodiments above of the invention, the UE can decide whether to transmit an SRS, according to whether transmission frequency resources of an SRS overlap with a narrowband for transmitting data, or whether adjacent narrowbands for transmitting data are the same, that is, there is provided a new SRS transmission rule to address the absence of a definite SRS transmission rule in the prior art particularly when the embodiments of the invention are applied to a low-complexity MTC system.

