CN107046732B

CN107046732B - Uplink frame transmission method and device

Info

Publication number: CN107046732B
Application number: CN201610084046.5A
Authority: CN
Inventors: 陶涛; 刘建国; 孟艳; 叶思根; 谷俊嵘
Original assignee: Alcatel Lucent SAS
Current assignee: Alcatel Lucent SAS
Priority date: 2016-02-05
Filing date: 2016-02-05
Publication date: 2020-04-17
Anticipated expiration: 2036-02-05
Also published as: WO2017134527A1; CN107046732A

Abstract

The embodiment of the disclosure discloses an uplink frame transmission method and device. The method comprises the following steps: reserving a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS); and performing Clear Channel Assessment (CCA) detection at the reserved time domain resources. The method may further comprise: reserving a specific time domain resource before an OFDM symbol for transmitting Physical Uplink Shared Channel (PUSCH) data, and performing CCA detection at the reserved time domain resource. The embodiment of the disclosure also discloses a corresponding uplink frame transmission device. The embodiment of the disclosure provides a technical scheme for supporting SRS transmission and PUSCH transmission in licensed spectrum assisted access (LAA), and improves the reliability and effectiveness of the SRS transmission and the PUSCH transmission.

Description

Uplink frame transmission method and device

Technical Field

Embodiments of the present disclosure generally relate to the field of wireless communications, and in particular, to an uplink frame transmission method and apparatus.

Background

In current LTE systems, data transmission occurs over Licensed Spectrum (Licensed Spectrum), however, with the dramatic increase in traffic, Licensed Spectrum may have difficulty meeting the traffic demand. The 3GPP has started to study LTE deployment on unlicensed spectrum, and proposed the concept of Licensed Assisted Access (LAA), which uses unlicensed frequency bands with the help of LTE licensed spectrum. Communication over LAA requires the application of a carrier sense (LBT) mechanism, i.e. a Clear Channel Assessment (CCA) is applied to sense whether a channel is available before communication using the unlicensed spectrum, in order to prevent interference of communication over the unlicensed band.

Channel Sounding Reference Signal (SRS) transmission on the LTE system uplink is used to maintain uplink timing and facilitate uplink and downlink scheduling by the eNB based on channel estimation and exploiting channel reciprocity. Therefore, for the same reason, it is desirable to support SRS transmission on an unlicensed band for uplink transmission.

Since the SRS signal does not have to be transmitted together with any uplink physical channel, there are two main transmission cases, i.e., SRS is transmitted in the same subframe as Physical Uplink Shared Channel (PUSCH) data, or SRS is transmitted separately in a subframe without PUSCH transmission. Considering that communication over LAA requires application of a carrier sensing mechanism, there is currently no solution that supports the two SRS transmission scenarios described above in LAA.

Disclosure of Invention

Based on the above problems, the embodiments of the present disclosure provide a technical solution for supporting SRS and PUSCH transmission in LAA by reserving specific time domain resources before SRS transmission and considering support for LBT procedure of PUSCH data transmission, thereby improving reliability and effectiveness of SRS transmission and PUSCH transmission.

According to a first aspect of the present disclosure, there is provided an uplink frame transmission method, including: reserving a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS); and performing Clear Channel Assessment (CCA) detection at the reserved time domain resources.

According to an embodiment of the disclosure, the method further comprises: reserving a particular time domain resource reservation immediately preceding an OFDM symbol for transmitting Physical Uplink Shared Channel (PUSCH) data, and performing CCA detection at the reserved time domain resource.

According to an embodiment of the disclosure, the method further comprises: the cell-specific SRS subframe is configured such that the SRS signal is transmitted on the last OFDM symbol or the first OFDM symbol of the cell-specific SRS subframe.

According to an embodiment of the present disclosure, the method further comprises: and reserving time domain resources at the tail part of a previous subframe of the special SRS subframe of the cell for supporting CCA detection of SRS transmission when the SRS signal is transmitted on a first OFDM symbol of the special SRS subframe of the cell.

According to an embodiment of the present disclosure, the method further comprises: and reserving time domain resources at the tail part of each uplink subframe when the SRS signal is transmitted on the first OFDM symbol of the special SRS subframe of the cell for supporting CCA detection of SRS transmission and/or PUSCH transmission.

According to an embodiment of the present disclosure, the method further comprises: when an SRS signal is transmitted on the first OFDM symbol of a cell-specific SRS subframe and PUSCH data is transmitted in a cell-specific subframe, the PUSCH data is transmitted immediately adjacent to the SRS signal.

According to an embodiment of the present disclosure, the method further comprises: when the last OFDM symbol of the cell-specific SRS subframe transmits the SRS signal, reserving the initial part of time domain resources of each uplink subframe, and reserving the part of time domain resources immediately before the OFDM symbol for transmitting the SRS signal for supporting CCA detection of SRS transmission and/or PUSCH transmission.

According to an embodiment of the disclosure, the method further comprises: wherein the reserved portion of the time domain resources comprises time domain resources corresponding in time to one OFDM symbol, or to more than one OFDM symbol, or to less than one OFDM symbol.

According to an embodiment of the disclosure, the method further comprises: configuring a downlink-uplink switching subframe such that when only one OFDM symbol is used for uplink in the downlink-uplink switching subframe, no SRS signal is transmitted in the downlink-uplink switching subframe.

According to an embodiment of the disclosure, the method further comprises: reserving a last OFDM symbol of the downlink-uplink switching subframe for supporting CCA detection of uplink subframe transmission after the downlink-uplink switching subframe.

According to an embodiment of the disclosure, the method further comprises: when a downlink-uplink switching subframe is used and two OFDM symbols in the downlink-uplink switching subframe are used for uplink, an SRS signal is transmitted at the last OFDM of the downlink-uplink switching subframe, and the last OFDM symbol of the downlink-uplink switching subframe is reserved for CCA detection supporting SRS transmission.

According to a second aspect of the present disclosure, there is provided an uplink frame transmission apparatus, the apparatus including: a transmission unit configured to reserve a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS); and a CCA detection unit configured to perform Clear Channel Assessment (CCA) detection at the reserved time domain resources.

According to an embodiment of the disclosure, the transmission unit is further configured to: reserving a particular time domain resource reservation immediately preceding an OFDM symbol for transmitting Physical Uplink Shared Channel (PUSCH) data, and performing CCA detection at the reserved time domain resource.

According to an embodiment of the disclosure, the transmission unit is further configured to: the cell-specific SRS subframe is configured such that the SRS signal is transmitted on the last OFDM symbol or the first OFDM symbol of the cell-specific SRS subframe.

According to an embodiment of the disclosure, the transmission unit is further configured to: and reserving time domain resources at the tail part of a previous subframe of the special SRS subframe of the cell for supporting CCA detection of SRS transmission when the SRS signal is transmitted on a first OFDM symbol of the special SRS subframe of the cell.

According to an embodiment of the disclosure, the transmission unit is further configured to: and reserving time domain resources at the tail part of each uplink subframe when the SRS signal is transmitted on the first OFDM symbol of the special SRS subframe of the cell for supporting CCA detection of SRS transmission and/or PUSCH transmission.

According to an embodiment of the disclosure, the transmission unit is further configured to: when the SRS signal is transmitted on the first OFDM symbol of the cell-specific SRS subframe and the PUSCH data is transmitted in the cell-specific subframe, the PUSCH data is transmitted immediately adjacent to the SRS signal.

According to an embodiment of the disclosure, the transmission unit is further configured to: when the SRS signal is transmitted in the last OFDM symbol of the cell-specific SRS subframe, reserving the initial part of time domain resources of each uplink subframe, and simultaneously reserving the part of time domain resources immediately before the OFDM symbol for transmitting the SRS signal for supporting CCA detection of SRS transmission and/or PUSCH transmission.

According to an embodiment of the present disclosure, further comprising: wherein the reserved portion of the time domain resources comprises time domain resources corresponding in time to one OFDM symbol, or to more than one OFDM symbol, or to less than one OFDM symbol.

According to an embodiment of the disclosure, the transmission unit is further configured to: configuring a downlink-uplink switching subframe such that when only one OFDM symbol is used for uplink in the downlink-uplink switching subframe, no SRS signal is transmitted in the downlink-uplink switching subframe.

According to an embodiment of the disclosure, the transmission unit is further configured to: reserving a last OFDM symbol of the downlink-uplink switching subframe for supporting CCA detection of uplink subframe transmission after the downlink-uplink switching subframe.

According to an embodiment of the disclosure, the transmission unit is further configured to: when a downlink-uplink switching subframe is used and two OFDM symbols in the downlink-uplink switching subframe are used for uplink, an SRS signal is transmitted at the last OFDM of the downlink-uplink switching subframe, and the last OFDM symbol of the downlink-uplink switching subframe is reserved for CCA detection supporting SRS transmission.

Considering the need to transmit SRS and PUSCH data in LAA, embodiments of the present disclosure enable application of LBT mechanism before transmission, improving reliability and effectiveness of SRS transmission and PUSCH transmission, and in turn improving accuracy of channel measurement and estimation.

Drawings

Embodiments of the present disclosure will be better understood and other objects, details, features and advantages thereof will become more apparent in the light of the following detailed description of non-limiting embodiments, which is set forth in the accompanying drawings. In the drawings:

fig. 1 is a diagram illustrating SRS transmission for performing CCA detection in existing LTE;

fig. 2 is a flowchart illustrating an uplink frame transmission method according to an embodiment of the disclosure;

fig. 3 is a schematic diagram of uplink frame transmission according to one embodiment of the present disclosure;

fig. 4 is a schematic diagram of uplink frame transmission according to another embodiment of the present disclosure;

fig. 5 is a schematic diagram of uplink frame transmission according to yet another embodiment of the present disclosure;

fig. 6 is an example diagram illustrating a scenario supporting different uplink transmissions in accordance with an embodiment of the present disclosure; and

fig. 7 is a schematic diagram of an uplink frame transmission apparatus according to an embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The accompanying drawings illustrate by way of example only certain embodiments in which the disclosure may be practiced, and are not intended to be exhaustive of all embodiments in accordance with the disclosure. Alternative embodiments may be devised from the following description and may be modified in structure or logically by those skilled in the art without departing from the spirit and scope of the embodiments of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of embodiments of the present disclosure is defined by the appended claims. It should be noted that although the steps of methods of embodiments of the present disclosure are depicted in the drawings in a particular order, this does not require or imply that these operations must be performed in this particular order, or that all of the illustrated operations must be performed, to the extent possible, the order of execution of the steps described herein may be altered. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions.

In LTE systems, SRS signals are typically transmitted on the last OFDM symbol of a cell-specific SRS subframe. Meanwhile, as mentioned earlier, SRS is not necessarily transmitted with any uplink physical channel, two SRS transmission scenarios from the User Equipment (UE) perspective are allowed in LTE Rel-12, namely: the SRS is transmitted within the same subframe as the PUSCH data, or independently transmitted within one subframe without PUSCH data transmission. However, if the SRS is transmitted together with other physical channels (e.g. PUSCH), the SRS transmitted by one UE in a certain subframe may overlap with the PUSCH transmitted by other UEs in the cell in the frequency domain. In order to avoid collision between SRS and PUSCH transmissions of different UEs, SRS subframe configuration is done at cell level, so all UEs know the cell-specific SRS subframe configuration and thus no UE in a cell transmits PUSCH data on the OFDM symbols used for SRS transmission in the cell-specific SRS subframe.

Since the LAA requires the LBT mechanism to be applied, the LTE device listens and detects the idle channel in the unlicensed frequency band. The LBT mechanism monitors a channel at the time of evaluating CCA of a free channel, and starts to occupy an unauthorized frequency band for data transmission when detecting that the unauthorized frequency band is free.

Although SRS may be considered as "short control signaling transmission" according to the provisions in the EU standard for LBT, the UE may transmit SRS without LBT operation. With this option, the UE is able to transmit SRS regardless of the channel state, and SRS transmission opportunities will increase. In this case, however, channel measurements and estimates may be inaccurate because the interference level between the ideal and busy channels is very different, while the actual interference level is not estimated, while, without LBT operation, SRS transmissions may collide with transmissions from cells or other technologies (e.g., WIFI) and may suddenly degrade ongoing transmissions from co-existing networks. In summary, LBT will have to be applied to SRS transmission in LAA to improve channel measurement accuracy and avoid possible collisions with other nodes.

Fig. 1 shows a schematic diagram of directly adopting an LBT mechanism on existing LTE communication, i.e. an LBT procedure for SRS transmission is performed in a current frame structure. In fig. 1, a transmission scheme is shown for three UEs with different transmission configurations (UE1, UE2, UE3) on two subframes, wherein the first subframe is a cell-specific SRS subframe and the second subframe is a non-SRS (non-SRS) subframe, while UE1 and UE2 are configured or triggered to transmit SRS in the first subframe and UE1 also transmits PUSCH data in the same subframe, while UE2 has no PUSCH transmission and therefore needs to transmit SRS separately by itself, while UE3 is not configured or triggered to transmit SRS data in the first subframe, which is configured to transmit PUSCH data in two subframes. In this case, due to PUSCH transmissions by other nodes, e.g., UE1 and UE3, UE2 has a high chance of detecting that the channel is busy, which would result in CCA detection failure and failure to transmit SRS signals.

In addition, a UE3 without SRS configuration has to interrupt PUSCH transmission to protect SRS transmission from intra-cell nodes. To resume PUSCH transmission, the UE3 should again detect channel availability. However, since the LBT procedure is blocked by intra-cell SRS transmission, its CCA detection result is likely to be busy, resulting in failure to recover PUSCH transmission.

Therefore, a new frame structure and transmission manner are required to support SRS transmission in LAA. Embodiments of the present disclosure provide an uplink frame transmission method to support channel detection for SRS transmission and PUSCH transmission on an unlicensed carrier, while still maintaining the advantages of the existing LTE frame structure.

Fig. 2 shows a method flow diagram according to an embodiment of the present disclosure.

At step S201, according to one embodiment of the present disclosure, a specific time domain resource immediately preceding an OFDM symbol used for transmitting SRS signals is reserved for CCA detection supporting SRS transmission. In this step, no signal may be transmitted on the reserved time domain resources in order to support SRS transmission to be performed.

At step S202, Clear Channel Assessment (CCA) detection is performed at the reserved time domain resources. In this step, the UE may perform clear channel assessment detection at the reserved time domain resources using, for example, "energy sounding," such as detecting a channel at the reserved time domain resources, considering the channel as occupied if the energy level in the channel exceeds a power level threshold, and may transmit immediately if the channel is found to be clear or referred to as "clean.

According to another embodiment of the present disclosure, a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS) is reserved; and performing Clear Channel Assessment (CCA) detection at the reserved time domain resources. The procedure is similar to that described above for CCA detection in support of SRS transmissions.

Because each UE in the cell is provided with CCA detection at the reserved time domain resource before transmitting SRS or PUSCH data, the uplink transmission of each UE reduces the interference on the transmission of other equipment on an unauthorized frequency band, and simultaneously can effectively transmit the SRS and PUSCH data according to the channel state.

It should be noted that, for the reserved time domain resources, which may correspond to one OFDM symbol in time, or more than one OFDM symbol in time, or even less than one OFDM symbol in time, for example, the reserved time domain resources may be set reasonably according to specific application scenarios, for example, considering the capability of the UE, the LAA system capacity, the load of other communication systems on the unlicensed frequency band, and the like.

The time domain resource reservation involved in embodiments of the present disclosure is specifically described below for the following three different subframe scenarios.

● case of cell-specific SRS subframes

According to one embodiment of the disclosure, in a cell-specific SRS subframe, a certain time domain resource is reserved immediately before a configured SRS symbol. For example, uplink transmissions may be left blank on the reserved corresponding OFDM symbols. Thus, the reserved time domain resources give the opportunity to perform LBT procedures, whether for SRS transmission alone, SRS transmission with PUSCH, or PUSCH transmission without SRS configured in a cell-specific SRS subframe, may be used for CCA detection.

As a specific example, considering that the SRS is always transmitted in the last OFDM symbol of a subframe in current LTE, the reserved time domain resource may be a resource before the last OFDM symbol in the SRS subframe configured by the current SRS in LTE, for example, may be located at the second last OFDM symbol in the subframe.

As another specific example, the SRS transmission position may be moved to the first OFDM symbol of the subframe, and at this time, the reserved time domain resource may be the end portion time domain resource of the previous subframe, for example, may be located at the last OFDM symbol of the previous subframe. This situation would be beneficial for locating the LBT position in the uplink subframe, where the reserved time domain resources may be located at the last OFDM symbol of the uplink subframe.

According to another embodiment of the present disclosure, when the UE is not configured or triggered for SRS transmission on a cell-specific SRS subframe and is scheduled to follow a PUSCH transmission of an SRS symbol, the UE still performs an LBT procedure on the reserved time domain resources and, if the LBT procedure is successful, transmits a reservation signal in the symbol for transmitting SRS to maintain the channel for a subsequent PUSCH transmission. At this time, the UE transmits the reservation signal without affecting SRS transmission by other user equipments. This would be beneficial so that PUSCH transmissions configured for the UE can be uninterrupted.

According to yet another embodiment of the present disclosure, in order to enable CCA detection for PUSCH transmission and SRS transmission, respectively, a starting partial time domain resource of each cell-specific subframe and a partial time domain resource immediately before an SRS symbol may be reserved, for example.

● case of non-SRS (common) subframes

According to one embodiment of the present disclosure, a time domain resource immediately before a starting point (e.g., a subframe boundary or OFDM symbol #1) where PUSCH is to be transmitted next is reserved. As a specific example, for the purpose of CCA detection for SRS transmission or PUSCH transmission, the end portion time domain resources of each non-SRS subframe are reserved, e.g., the last OFDM symbol of each non-SRS subframe is reserved. As another specific example, for the purpose of CCA detection for PUSCH transmission, a partial time domain resource is started for each uplink subframe, e.g., the first OFDM symbol of each uplink subframe.

● case of downlink-uplink switching subframe

According to one embodiment of the present disclosure, for a downlink-uplink handover subframe, e.g., a special subframe in lte tdd, if there is only one symbol for uplink, the present disclosure proposes that SRS transmission should not be configured or triggered in this downlink-uplink handover subframe, since there may not be enough time for the UE to perform the LBT procedure.

SRS transmission may be configured or triggered in a downlink-uplink handover subframe if there are more than two symbols for uplink. If SRS transmission is configured or triggered, e.g., the second to last symbol in a downlink-uplink handover subframe is reserved for the LBT procedure for SRS, while the last symbol is used for SRS transmission. Alternatively, only a portion of the time domain resources corresponding to the second last symbol may be reserved.

As mentioned above, in order to comply with LBT procedures on unlicensed carriers, the UE should perform CCA detection before SRS transmission, and SRS is transmitted only when the channel is idle. By adopting the scheme provided by the disclosure, CCA detection of the SRS and the PUSCH is realized, and the problems that when the UE performs channel sounding and the UE in other cells has data transmission, CCA detection is possibly unreliable and SRS transmission is possibly blocked are solved.

Various specific embodiments will be described below in conjunction with fig. 3-5 to more clearly understand the principles and spirit of the present disclosure. It should be noted that the embodiments of the present disclosure are for ease of understanding only, and the various embodiments are described by way of example, not limitation, and not exhaustive.

In addition, for the sake of convenience of description, the reservation of the time domain resources in the following examples is only taken as an example corresponding to one OFDM symbol, and as mentioned above, for the reservation of the time domain resources, the embodiments of the present disclosure are not limited to the case corresponding to one OFDM symbol, and those skilled in the art will readily understand that there may be several different specific implementations without departing from the spirit or essential features of the embodiments of the present disclosure.

Fig. 3 is an example diagram of uplink frame transmission in LAA according to one embodiment of the disclosure. The downlink-uplink switching subframe takes a TDD special subframe in LTE as an example, UpPTS only occupies one OFDM symbol, PUSCH data is configured and transmitted in a non-SRS subframe, and PUSCH data and SRS signals are configured and transmitted in an SRS subframe.

In this embodiment, since the UpPTS occupies only one OFDM symbol in the special subframe, SRS transmission is not allowed in the special subframe, but an LBT procedure for the next uplink subframe transmission may be completed in the UpPTS, and thus a symbol in the UpPTS is reserved. And configuring PUSCH data transmission in a non-SRS subframe, wherein the last OFDM symbol of the subframe is reserved for CCA detection. In the SRS subframe, the second to last OFDM symbol is reserved for CCA detection and the last OFDM symbol is reserved for SRS transmission.

As can be seen from this embodiment, the LBT procedure may be performed in the last OFDM symbol or the second to last OFDM symbol of the subframe. According to another embodiment of the present disclosure, to locate the position of the LBT in the SRS subframes and the non-SRS subframes, the position of SRS transmission may be moved to the first OFDM symbol of the cell-specific SRS subframe, as shown in fig. 4. In this case, the last symbol of each subframe is reserved for LBT. At this time, if the SRS is transmitted together with the PUSCH data, since other users in the cell all transmit the SRS on the first OFDM symbol of the subframe, the subsequent PUSCH transmission of the UE may continue without affecting the SRS transmission at this time, and thus the PUSCH data may be directly transmitted after the SRS transmission.

In another embodiment, the first OFDM symbol of each uplink subframe is reserved for CCA detection purposes of PUSCH transmission. And, for CCA detection of SRS transmissions, the OFDM symbol immediately preceding the SRS symbol is reserved. This situation is illustrated in fig. 5. In fig. 5, two OFDM symbols are reserved in the SRS subframe, and in the worst case, if there is SRS transmission in each uplink subframe, the transmission overhead will be greatly increased, but the uplink frame configuration in this embodiment has the least impact on the existing LTE frame structure.

It should be understood that the uplink frame transmission schemes proposed by the present disclosure have been described above only by way of different specific examples, not exhaustively, to support channel detection for SRS transmission and PUSCH transmission on an unlicensed carrier, and those skilled in the art will readily appreciate that there are many different uplink frame transmission schemes and that embodiments of the present disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics thereof.

Fig. 6 gives an example of a situation how the proposed solution according to the present disclosure supports different uplink transmissions. As shown in fig. 6, the first subframe is an uplink subframe configured with a cell/user dedicated SRS subframe, and the second subframe is a normal uplink subframe. Assume the following scenario:

UE1 is scheduled for PUSCH transmission in two subframes, and SRS transmission is configured in the first subframe;

UE2 is configured with SRS transmission in the first subframe and is not scheduled with PUSCH transmission in this subframe;

UE3 is scheduled for PUSCH transmission in two subframes;

UE4 is scheduled for PUSCH transmission only in the second subframe;

in the first subframe, PUSCH transmissions for UE1 and UE3 are multiplexed in the frequency domain; in the second subframe, PUSCH transmissions for UE1, UE3, and UE4 are multiplexed in the frequency domain.

According to the scheme provided by the embodiment of the present disclosure, the uplink transmission specifically for each UE may be as follows:

for UE1, the LBT procedure for PUSCH transmission in the first subframe is performed in the last OFDM symbol of the previous normal subframe. PUSCH transmissions are from OFDM symbols #0 to #11 in the SRS subframe. The LBT procedure for SRS transmission is performed in the second to last OFDM symbol of the first subframe. Since the UE1 is also scheduled for PUSCH transmission in the second subframe, the PUSCH can be transmitted in the second subframe directly after SRS transmission while reserving the last OFDM symbol of the second subframe for CCA detection for subsequent transmissions, i.e., PUSCH transmission on OFDM symbols #0 to #12 in non-SRS subframes.

For UE2, it detects channel availability in the second to last OFDM symbol of the first subframe. If the channel is detected as idle, the UE2 individual SRS may be transmitted.

For the UE3, which is not configured or triggered for SRS transmission, the LBT process is performed in the second to last OFDM symbol in the SRS subframe and in the last OFDM symbol in the non-SRS subframe. At this point, since data transmission is not allowed in the last OFDM symbol of the SRS subframe in order to protect SRS transmissions from other UEs within the cell, a reservation signal should be transmitted by the UE3 to occupy the channel. For example, the reservation signal may be an SRS sequence that is orthogonal to existing SRS sequences. Alternatively, the reservation signal may be a UE-specific sequence transmitted on PUSCH resources for channel reservation.

For UE4, which is scheduled for PUSCH transmission in non-SRS subframes only, uplink transmission is similar to the procedure of UE 3.

Fig. 7 is a schematic diagram of an uplink frame transmission apparatus according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, there is provided an uplink frame transmission apparatus including: a transmission unit 701 configured to reserve a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS); and a CCA detection unit configured to perform Clear Channel Assessment (CCA) detection at the reserved time domain resources.

According to an embodiment of the present disclosure, further comprising: wherein the reserved time domain resources comprise time domain resources corresponding in time to one OFDM symbol, or time domain resources corresponding to more than one OFDM symbol, or time domain resources corresponding to less than one OFDM symbol.

Many modifications and other embodiments of the disclosure set forth herein will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments of the disclosure are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the disclosure. Moreover, while the above description and the related figures describe example embodiments in the context of certain example combinations of components and/or functions, it should be appreciated that different combinations of components and/or functions may be provided by alternative embodiments without departing from the scope of the present disclosure. In this regard, for example, other combinations of components and/or functions than those explicitly described above are also contemplated as within the scope of the present disclosure. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. An uplink frame transmission method includes:

reserving a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS); and

performing Clear Channel Assessment (CCA) detection at the reserved time domain resources;

when only one OFDM symbol in a downlink-uplink switching subframe is used for uplink, reserving the last OFDM symbol of the downlink-uplink switching subframe for supporting CCA detection of uplink subframe transmission after the downlink-uplink switching subframe.

2. The method of claim 1, further comprising:

reserving a specific time domain resource reservation immediately preceding an OFDM symbol for transmission of Physical Uplink Shared Channel (PUSCH) data, and

performing CCA detection at the reserved time domain resources.

3. The method of claim 1 or 2, further comprising:

configuring a cell-specific SRS subframe such that the SRS signals are transmitted on a last OFDM symbol or a first OFDM symbol of the cell-specific SRS subframe.

4. The method of claim 3, further comprising:

when the SRS signal is transmitted on the first OFDM symbol of the special SRS subframe of the cell, reserving the time domain resource at the tail part of the previous subframe of the special SRS subframe of the cell for supporting CCA detection of SRS transmission.

5. The method of claim 3, further comprising:

and reserving time domain resources at the tail part of each uplink subframe when the SRS signal is transmitted on the first OFDM symbol of the special SRS subframe of the cell for supporting CCA detection of SRS transmission and/or PUSCH transmission.

6. The method of claim 3, further comprising:

transmitting the SRS signal on a first OFDM symbol of the cell-specific SRS subframe, and transmitting PUSCH data in the cell-specific subframe, the PUSCH data being transmitted immediately adjacent to the SRS signal.

7. The method of claim 3, further comprising:

when an SRS signal is transmitted in the last OFDM symbol of the cell-specific SRS subframe, reserving the initial part of time domain resources of each uplink subframe, and simultaneously reserving the part of time domain resources immediately before the OFDM symbol for transmitting the SRS signal for supporting CCA detection of SRS transmission and/or PUSCH transmission.

8. A method as claimed in claim 1, wherein the reserved time domain resources comprise time domain resources corresponding in time to one OFDM symbol, or time domain resources corresponding to more than one OFDM symbol, or time domain resources corresponding to less than one OFDM symbol.

9. The method of claim 1, further comprising:

configuring the downlink-uplink switching subframe so that when only one OFDM symbol in the downlink-uplink switching subframe is used for uplink, no SRS signal is transmitted in the downlink-uplink switching subframe.

10. The method of claim 1, further comprising:

when a downlink-uplink switching subframe is used and two OFDM symbols in the downlink-uplink switching subframe are used for uplink, the SRS signal is transmitted at the last OFDM of the downlink-uplink switching subframe, and the last OFDM symbol of the downlink-uplink switching subframe is reserved for CCA detection supporting SRS transmission.

11. An uplink frame transmission apparatus, comprising:

a transmission unit configured to reserve a specific time domain resource immediately before an OFDM symbol for transmitting a channel Sounding Reference Signal (SRS), wherein when only one OFDM symbol in a downlink-uplink switching subframe is used for uplink, a last OFDM symbol of the downlink-uplink switching subframe is reserved for supporting Clear Channel Assessment (CCA) detection of uplink subframe transmission after the downlink-uplink switching subframe; and

a CCA detection unit configured to perform CCA detection at the reserved time domain resource.

12. The apparatus of claim 11, wherein the transmission unit is further configured to:

the CCA detection unit is further configured to:

performing CCA detection at the reserved time domain resources.

13. The apparatus according to claim 11 or 12, wherein the transmission unit is further configured to:

14. The apparatus of claim 13, wherein the transmission unit is further configured to:

15. The apparatus of claim 13, wherein the transmission unit is further configured to:

16. The apparatus of claim 13, wherein the transmission unit is further configured to:

17. The apparatus of claim 13, wherein the transmission unit is further configured to:

18. An apparatus according to claim 11, wherein the reserved time domain resources comprise time domain resources corresponding in time to one OFDM symbol, or time domain resources corresponding to more than one OFDM symbol, or time domain resources corresponding to less than one OFDM symbol.

19. The apparatus of claim 11, wherein the transmission unit is further configured to:

20. The apparatus of claim 11, wherein the transmission unit is further configured to: