Patent Description:
Rapid growth of mobile data forces operators to utilize the finite frequency spectrum with higher and higher efficiency, while plenty of unlicensed frequency spectra are utilized less efficiently only by WiFi, Bluetooth, etc. LTE-U (LTE-unlicensed) can extend the LTE spectrum to unlicensed band that would augment the network capacity directly and dramatically. LTE-U with LAA (Licensed Assisted Access) has higher spectrum efficiency than WiFi especially when massive users, e.g. reliable CCH (Control CHannel), LA (Link Adaption), HARQ, ICIC (Inter Cell Interference Coordination), interference cancellation. LTE-U can well co-exist with the existed RATs by mechanisms such as LBT (Listen Before Talk), DFS (Dynamic Frequency Selection), TPC (Transmit Power Control). Network architecture will be simpler and more unified.

<CIT> relates to a method for transmitting a signal to an unlicensed band of a base station in a wireless communication system.

The invention is defined only in the appended independent claims.

Examples mentioned in the following description that do not necessarily fall under the scope of the appended claims are to be construed as comparative examples useful for understanding the present invention.

In a first aspect of the present disclosure, there is provided a resource scheduling method for wireless communication performed by an eNode B (eNB), the wireless communication involving at least a first carrier and a second carrier, and the method comprising: transmitting a downlink control information (DCI) in the first carrier to a user equipment (UE) to schedule downlink resources for a physical downlink shared channel (PDSCH) of the second carrier, wherein the eNB is able to start transmitting a burst in the second carrier at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH.

In a second aspect of the present disclosure, there is provided a resource determining method for wireless communication performed by a user equipment (UE), the wireless communication involving at least a first carrier and a second carrier, and the method comprising: receiving a downlink control information (DCI) transmitted in the first carrier by a eNode B (eNB) to determine downlink resources for a physical downlink shared channel (PDSCH) of the second carrier, wherein the UE is able to receive a burst in the second carrier started by the eNB at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH.

In a third aspect of the present disclosure, there is provided an eNode B (eNB) for resource scheduling of wireless communication, the wireless communication involving at least a first carrier and a second carrier, and the eNB comprising: a transmitting unit configured to transmit a downlink control information (DCI) in the first carrier to a user equipment (UE) to schedule downlink resources for a physical downlink shared channel (PDSCH) of the second carrier, wherein the eNB can start to transmit a burst in the second carrier at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH.

In a fourth aspect of the present disclosure, there is provided a user equipment (UE) for resource determining of wireless communication, the wireless communication involving at least a first carrier and a second carrier, and the method comprising: a receiving unit configured to receive a downlink control information (DCI) transmitted in the first carrier by a eNode B (eNB) to determine downlink resources for a physical downlink shared channel (PDSCH) of the second carrier, wherein the UE is able to receive a burst in the second carrier started by the eNB at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH.

In the present disclosure, the flexible PDSCH and its corresponding reference signal (RS) can reuse the DwPTS subframe structure for minimal specification impact.

The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several aspects in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings, in which:.

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. It will be readily understood that the aspects of the present disclosure can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

How to schedule resources of unlicensed carrier by eNB is an important issue that needs to be resolved in LAA. LTE Carrier aggregation architecture (licensed PCell and unlicensed SCell) is a basic assumption. Cross-carrier scheduling by licensed band is a natural mechanism in carrier aggregation to grant resources in unlicensed carriers due to reliable control signaling transmission in licensed carrier. Aligned subframes between licensed carrier and unlicensed carrier could reuse the current scheduling mechanisms in LTE carrier aggregation. In cross-carrier scheduling mechanism currently existing, control and data are sent in the same subframe time but on different carriers. The eNB can access the unlicensed channel just at fixed points of time (e.g. PDSCH boundary or subframe boundary), while other nodes such as Wi-Fi can access the channel immediately after successful CCA (Clear Channel Assessment). In this sense, the access priority of LAA would be de-prioritized compared with Wi-Fi.

In the present disclosure, a mechanism of flexibly scheduling the starting time of a burst in the unlicensed carrier (also referred to as unlicensed band) is provided. In other words, the eNB can start to transmit a burst in the unlicensed carrier at a flexible time independent of the subframe boundaries after the unlicensed carrier is occupied by the eNB (e.g., after successful CCA). In particular, the starting time of PDSCH in the burst can be flexibly scheduled. By flexibly scheduling the starting time of the burst or the PDSCH, the eNB has the possibility to occupy the unlicensed carrier at any moment independent of the subframe boundary immediately after successful CCA.

It is noted that although aspects of the present disclosure may be described in the context of licensed band and unlicensed band, the present disclosure is not limited to it but can be applied to any wireless communication involving two different carriers which are referred to a first carrier (e.g., the licensed carrier) and a second carrier (e.g. the unlicensed carrier) in the present disclosure.

According to the present disclosure, there is provided a resource scheduling method for wireless communication performed by an eNB. The wireless communication involves at least a first carrier (e.g. the licensed carrier) and a second carrier (e.g. the unlicensed carrier). A flowchart of the resource scheduling method is illustrated in <FIG> as method <NUM>. The method <NUM> comprises a step <NUM> of transmitting a DCI in the first carrier to a UE to schedule downlink resources for a PDSCH of the second carrier, wherein the eNB can start to transmit a burst in the second carrier at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH. Preferably, subframes of the second carrier are aligned with subframes of the first carrier, which can reuse the current scheduling mechanisms in LTE carrier aggregation. It is noted that the normal PDSCH here refer to the PDSCH with fixed boundaries and length. If the subframe of the second carrier has no PDCCH, the boundaries of the normal PDSCH are the same as the boundaries of the subframe. If the subframe has PDCCH, the starting boundary of the normal PDSCH is the ending of the PDCCH and the ending boundary of the normal PDSCH is the ending boundary of the subframe in which the normal PDSCH resides. The flexible PDSCH here refers to a PDSCH different from the normal PDSCH. For example, the starting time and/or the ending time of the flexible PDSCH is shifted from respective boundaries of the normal PDSCH. The length of the flexible PDSCH can be shorter or longer than the normal PDSCH.

According to the method <NUM>, the eNB can start a burst in the second carrier at a flexible time after successful CCA without being limited by the subframe boundaries. Herein, the term "flexible" means the stating time is not limited to the subframe boundaries or the normal PDSCH boundaries and can be changed as required. For example, the eNB can start to transmit signals immediately after successful CCA. The signals can be a reservation signal such as RTS/CTS (Request To Send/Clear To Send) or other signals followed by PDSCH(s), or only PDSCH(s). When transmitting PDSCH, its granularity can be one OFDM symbol. In other words, the flexible starting time of the first PDSCH in the burst can be the first available OFDM symbol after the ending time of the successful CCA. In this way, the eNB has the possibility to occupy the second carrier at any moment independent of the subframe boundary immediately after successful CCA.

In addition, since the starting time of the burst is flexibly scheduled, the first and/or the last PDSCH in the burst may not be aligned with normal PDSCHs; therefore, according to method <NUM>, the DCI for a flexible PDSCH of the burst contains information on the time period scheduled for the flexible PDSCH. Probably, the DCI for the first or the last PDSCH in the burst may be the flexible PDSCH. As for normal PDSCHs, the DCI defined in the present disclosure may also be used, in other words, the normal PDSCH and the flexible PDSCH may use the same DCI format, details of which will be described later. It is noted that the information on the time period is not necessarily to contain the starting time and the ending time of the PDSCH, but can be any information which can derive the time period. For example, the information can be the ending time or the starting time and the length of the PDSCH. Alternatively, if the starting time or the ending time is known to the UE, only the length may need to be contained. According to the present disclosure, the DCI can be sent in an PDCCH or EPDCCH ((E)PDCCH) of the first carrier after the second channel is occupied by the eNB; alternatively the DCI can also be sent in an (E)PDCCH of the first carrier before the second channel is occupied by the eNB. In addition, the DCI can be sent in a same or different subframe with the subframe sending the PDSCH, and can be sent before or after sending the PDSCH even in the same subframe (here, the term of "before" or "after" means the starting of the sending is "before" or "after"). For example, if the EPDCCH is used in the first carrier to send the DCI, the PDSCH in the second carrier can start to be sent before the starting of the EDPCCH in the same subframe. Alternatively, in particular, the DCI can be sent in the next subframe to the subframe starting the PDSCH transmission.

According to method <NUM>, some PDSCH, in particular the first PDSCH and the last PDSCH, in the burst may have different length with a normal PDSCH. For example, the first PDSCH may start in the first available OFDM symbol after the ending time of the successful CCA, and end at the ending boundary of the subframe in which the first PDSCH starts or at the ending boundary of the next subframe to the subframe in which the first PDSCH starts. The first PDSCH in the former case can be a shortened PDSCH which is shorter than a normal PDSCH (it may also be a normal PDSCH if the starting time of the first PDSCH happens to be at a boundary of a normal PDSCH), and the first PDSCH in the later case is an extended PDSCH which is one shortened or normal PDSCH plus one normal PDSCH. The shortened PDSCH and the extended PDSCH belong to the flexible PDSCH. According to the present disclosure, both shortened and extended PDSCH can be adopted based on designed strategy.

Preferably, the flexible PDSCH and its corresponding reference signal (RS) reuse the DwPTS (Downlink Pilot Time Slot) subframe structure. For example, for a shortened PDSCH, if the starting time of the shortened PDSCH is not at a starting time of a normal PDSCH (e.g., the first PDSCH in the flexible scheduling is usually the case), the shortened PDSCH using DwPTS subframe structure can be entirely shifted to start at the OFDM symbol scheduled by eNB. <FIG> schematically illustrates such shifting. It is noted that the existing DwPTS includes one or two OFDM symbols from the starting point as PDCCH. Therefore, when there is no PDCCH in the unlicensed band, two possibilities exist for the the shortened PDSCH, that is, the shortened PDSCH may start from the first OFDM symbol of the DwPTS or start from the second or the third OFDM symbol of the DwPTS. In addition, corresponding PDSCH mapping, RS pattern, and transport block size (TBS) table may be modified only if necessary.

In the present disclosure, an eNB for resource scheduling of wireless communication is also provided. The wireless communication involves at least a first carrier and a second carrier. <FIG> schematically illustrates a block diagram of such an eNB <NUM>. The eNB <NUM> comprises a transmitting unit <NUM> configured to transmit a DCI in the first carrier to a UE to schedule downlink resources for an PDSCH of the second carrier, wherein the eNB can start to transmit a burst in the second carrier at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH.

The eNB <NUM> according to the present disclosure may optionally include a CPU (Central Processing Unit) <NUM> for executing related programs to process various data and control operations of respective units in the eNB <NUM>, a ROM (Read Only Memory) <NUM> for storing various programs required for performing various process and control by the CPU <NUM>, a RAM (Random Access Memory) <NUM> for storing intermediate data temporarily produced in the procedure of process and control by the CPU <NUM>, and/or a storage unit <NUM> for storing various programs, data and so on. The above transmitting unit <NUM>, CPU <NUM>, ROM <NUM>, RAM <NUM> and/or storage unit <NUM> etc. may be interconnected via data and/or command bus <NUM> and transfer signals between one another.

Respective units as described above do not limit the scope of the present disclosure. According to one implementation of the disclosure, the functions of the above transmitting unit <NUM> may be implemented by hardware, and the above CPU <NUM>, ROM <NUM>, RAM <NUM> and/or storage unit <NUM> may not be necessary. Alternatively, the functions of the above transmitting unit <NUM> may also be implemented by functional software in combination with the above CPU <NUM>, ROM <NUM>, RAM <NUM> and/or storage unit <NUM> etc..

Accordingly, at the UE side, the present disclosure provides a resource determining method for wireless communication performed by a UE. The wireless communication involves at least a first carrier and a second carrier. <FIG> illustrates a flowchart of the resource determining method <NUM>. The method <NUM> comprises a step <NUM> of receiving a DCI transmitted in the first carrier by a eNB to determine downlink resources for a PDSCH of the second carrier, wherein the UE is able to receive a burst in the second carrier started by the eNB at a time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and at least the DCI for the first PDSCH of the burst and/or the DCI for the last PDSCH of the burst contains information on the time period scheduled for the respective PDSCH. It is noted that the above details described at the eNB side can also apply to the UE side, which will be repeated here.

In addition, the present disclosure also provides a UE for resource determining of wireless communication. The wireless communication involves at least a first carrier and a second carrier. <FIG> schematically illustrates a block diagram of such a UE <NUM>. The UE <NUM> comprises a receiving unit <NUM> configured to receive a DCI transmitted in the first carrier by an eNB to determine downlink resources for a PDSCH of the second carrier, wherein the UE is able to receive a burst in the second carrier started by the eNB at a flexible time independent of the subframe boundaries of the second carrier after the second carrier is occupied by the eNB, and the DCI for a flexible PDSCH of the burst different from the normal PDSCH of the second carrier contains information on the time period scheduled for the flexible PDSCH.

The UE <NUM> according to the present disclosure may optionally include a CPU (Central Processing Unit) <NUM> for executing related programs to process various data and control operations of respective units in the UE <NUM>, a ROM (Read Only Memory) <NUM> for storing various programs required for performing various process and control by the CPU <NUM>, a RAM (Random Access Memory) <NUM> for storing intermediate data temporarily produced in the procedure of process and control by the CPU <NUM>, and/or a storage unit <NUM> for storing various programs, data and so on. The above receiving unit <NUM>, CPU <NUM>, ROM <NUM>, RAM <NUM> and/or storage unit <NUM> etc. may be interconnected via data and/or command bus <NUM> and transfer signals between one another.

Respective units as described above do not limit the scope of the present disclosure. According to one implementation of the disclosure, the functions of the above receiving unit <NUM> may be implemented by hardware, and the above CPU <NUM>, ROM <NUM>, RAM <NUM> and/or storage unit <NUM> may not be necessary. Alternatively, the functions of the above receiving unit <NUM> may also be implemented by functional software in combination with the above CPU <NUM>, ROM <NUM>, RAM <NUM> and/or storage unit <NUM> etc..

In the following, the present disclosure will be described in detail by aspects.

In the first aspect, the eNB can transmit the first PDSCH of the burst starting with the first available OFDM symbol after the second carrier is occupied by the eNB (e.g. after successful CCA) and ending with the ending boundary of the subframe in which the first PDSCH starts. For example, after successful CCA in the unlicensed band, the eNB sends data in PDSCH which starts with the first OFDM symbol available for data transmission and ends with the ending boundary of the current subframe. It is noted that the first available OFDM symbol is not necessary to be the first OFDM symbol after CCA ending because a reservation signal such as preamble, PSS/SSS (Primary Synchronization Signal /Secondary Synchronization Signal) or RTS/CTS can be sent after CCA ending and before the first PDSCH. The first PDSCH of the burst in the first aspect can be a shortened PDSCH or a normal PDSCH.

<FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the first aspect of the present disclosure. As shown in <FIG>, in the unlicensed band, the data in the first PDSCH (which is a shortened PDSCH in <FIG>) can be sent by starting from the first symbol boundary after CCA, and optionally a reservation signal can be sent before the first PDSCH. When a reservation signal is sent before the first PDSCH, the first PDSCH may start with a subsequent symbol other than the first one, and said subsequent symbol can also be referred to as the first available symbol since the symbols before it is not available for PDSCH. The ending of the first PDSCH is the ending boundary of the current subframe, i.e., the <NUM>st subframe boundary as shown in <FIG>.

In case of normal CP (Cyclic Prefix) and no PDCCH region in the unlicensed band, the normal PDSCH consists of <NUM> OFDM symbols. The starting symbol of the flexibly started PDSCH (e.g., the first PDSCH of the burst in the aspect) can be the <NUM>st to <NUM>st symbol depending on CCA ending time, and thus the OFDM symbol number for the flexibly started PDSCH is from <NUM> to <NUM>. If the OFDM symbol number is smaller than <NUM>, the PDSCH is referred to as a shortened PDSCH. It is noted that if the length of the first PDSCH is <NUM> symbols, the first PDSCH is a normal PDSCH.

The shortened PDSCH and corresponding RS (Reference Signal) would reuse the DwPTS subframe structure for minimal specification impact. The shortened PDSCH using DwPTS subframe structure is entirely shifted to start at the OFDM symbol scheduled by eNB as shown in <FIG>. Only length of <NUM>/<NUM>/<NUM>/<NUM>/<NUM> symbols are defined for PDSCH with normal CP in current DwPTS, other length of the shortened PDSCH (if supported) can reuse the same structure and define new TBS (Transport Block Size) mapping as follows:.

In order to indicate the time period of the first PDSCH of the burst in the unlicensed carrier, a DCI would be sent at PDCCH/EPDCCH of the licensed band. The DCI can be sent after or before the unlicensed channel is occupied by the eNB. For example, the DCI can be sent in the subframe transmitting the first PDSCH or the next subframe. In the example of <FIG>, the DCI is sent in the next subframe. As an example, the DCI for the first PDSCH contains an ending indicator (i.e., ending subframe boundary field) to indicate whether the ending time of the first PDSCH is the starting boundary or the ending boundary of the subframe transmitting the DCI and a length indicator to indicate the length of the first PDSCH. It is noted that, in the first aspect, if the first PDSCH is a shortened PDSCH (one kind of flexible PDSCH), the above defined DCI will be used, that is, the above defined DCI is for the first PDSCH as the flexible PDSCH. As for the case of the first PDSCH being a normal PDSCH, a normal DCI can be used, or the above defined DCI can also be used. The selection of the DCI formats can be specified or configured. When the above defined DCI is used for a normal PDSCH (not only for the first PDSCH, but possibly also for other normal PDSCHs), the length of the PDSCH is set to be <NUM> in case of normal CP and no PDCCH region.

Specifically, for the ending subframe boundary field in DCI, one bit can be used to indicate the ending time (e.g., the ending subframe boundary) for example with respect to the subframe for sending the DCI in (E)PDCCH. For example, "<NUM>" indicates that the PDSCH ends at the starting boundary (<NUM>st subframe boundary in <FIG>) of the subframe sending the DCI, and "<NUM>" indicates that the PDSCH ends at the ending boundary(<NUM>nd subframe boundary in <FIG>) of the subframe sending the DCI.

For the length indicator for indicating the length of first PDSCH for example in terms of OFDM symbol, for example, <NUM> bits can be used to indicate the PDSCH length from <NUM> to <NUM> ("<NUM>" indicates a normal PDSCH) OFDM symbols. However, a reduced number of bits can also be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate. For example, a <NUM>-bit indicator can be used for length of <NUM>/<NUM>/<NUM>/<NUM> OFDM symbols, or a <NUM>-bit indicator can be used for length of <NUM>/<NUM> OFDM symbols.

The above method can also be applied to OFDM symbols with extended CP. According to the first aspect, buffering PDSCH with different lengths in eNB may be needed due to unpredictable time for successful CCA, and the UE may need to buffer one previous subframe for first PDSCH.

In the second aspect, the eNB can transmit the first PDSCH of the burst starting with the first available OFDM symbol after the second carrier is occupied by the eNB (e.g. after successful CCA) and ending with the ending boundary of the next subframe to the subframe (current subframe) in which the first PDSCH starts. For example, after successful CCA in the unlicensed band, the eNB sends data in PDSCH which starts with the first OFDM symbol available for data transmission and ends with the ending boundary of the next subframe to the current subframe. As described in the first aspect, it is noted that the first available OFDM symbol is not necessary to be the first OFDM symbol after CCA ending because a reservation signal such as preamble, RTS/CTS or PSS/SSS can be sent after CCA ending and before the first PDSCH. The first PDSCH of the burst in the second aspect is an extended PDSCH.

<FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the second aspect of the present disclosure. As shown in <FIG>, in the unlicensed band, the data in the first PDSCH (extended PDSCH) can be sent by starting from the first symbol boundary after CCA. Optionally, a reservation signal can also be sent before the first PDSCH. The ending of the first PDSCH is the ending boundary of the next subframe to the current subframe, i.e., the <NUM>nd subframe boundary as shown in <FIG>.

As described in the first aspect, in case of normal CP and no PDCCH region in the unlicensed band, a normal PDSCH consists of <NUM> OFDM symbols. Therefore, the first part (shortened PDSCH part) of the first PDSCH in the second aspect which starts from the first available OFDM symbol to the ending boundary of the current subframe can have <NUM> to <NUM> OFDM symbols. The first part is same as the first PDSCH in the first aspect. The second part (normal PDSCH part) of the first PDSCH is a normal PDSCH sending in the next subframe to the current subframe. In the second aspect, the first part of the first PDSCH is scheduled together with the second part as one extended PDSCH by one DCI in for example the subframe sending the second part to one (group of) UE.

The bits of the extended PDSCH could be:.

In the second aspect, in order to indicate the time period of the first PDSCH of the burst in the unlicensed carrier, a DCI would be sent at PDCCH/EPDCCH of the licensed band. The DCI can be sent after or before the unlicensed channel is occupied by the eNB. For example, the DCI can be sent in the subframe transmitting the first part or the second part of the first PDSCH. In the example of <FIG>, the DCI is sent in the subframe transmitting the second part. The DCI for the first PDSCH contains at least a length indicator to indicate the length of the first PDSCH, and can optionally contain an ending indicator to indicate the ending time of the first PDSCH. In the second aspect, since the subframe sending DCI can be fixed or configured to be either the subframe transmitting the first part of the first PDSCH or the subframe transmitting the second part, the UE can know the ending of the first PDSCH, and therefore, the ending indicator can be omitted. For the length indicator for indicating the length of first PDSCH for example in terms of OFDM symbol, for example, <NUM> bits can be used to indicate the PDSCH length from <NUM> to <NUM> OFDM symbols. Alternatively, a reduced number of bits can also be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate. For example, a <NUM>-bit indicator can be used for length of <NUM>/<NUM>/<NUM>/<NUM> OFDM symbols, or a <NUM>-bit indicator can be used for length of <NUM>/<NUM> OFDM symbols.

The above method can also be applied to OFDM symbols with extended CP. According to the aspect, buffering PDSCH with different lengths in eNB may be needed due to unpredictable time for successful CCA, and the UE may need to buffer one previous subframe for first PDSCH.

In the third aspect, the eNB transmits the first PDSCH of the burst starting with the first available OFDM symbol after the second carrier is occupied by the eNB and ending either with the ending boundary of the subframe in which the first PDSCH starts or with the ending boundary of the next subframe to the subframe in which the first PDSCH starts. Here, both the PDSCH scheduling mechanisms in the first aspect and the second aspect can be adopted by the eNB using one DCI format, and which one will be adopted would depend on scheduling strategy at eNB, in other words, whether the shortened PDSCH as in the first aspect or the extended PDSCH as in the second aspect will be scheduled would depend on scheduling strategy at eNB, and one DCI format is used for the two cases. It is noted that the DCI format in the third aspect can also be used for a normal PDSCH. In the third aspect, PDSCH mapping, RS mapping, TBS determination, and encoding can use the same methods as in the first aspect and the second aspect respectively.

The scheduling strategy at eNB can consider one or more of following features:.

In order to indicate the time period of the first PDSCH of the burst in the unlicensed carrier, a DCI would be sent at PDCCH/EPDCCH of the licensed band. The DCI can be sent after or before the unlicensed channel is occupied by the eNB. For example, <FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the third aspect of the present disclosure. As shown in <FIG>, three possible first PDSCHs in the unlicensed band are illustrated, the upper one is an extended PDSCH as described in the second aspect, the middle one is a normal PDSCH as a special case described in the first aspect, and the bottom one is a shortened PDSCH as described in the first aspect. In order to uniformly indicate the time period of the three PDSCH in one DCI format, the DCI for the first PDSCH can be transmitted in the subframe transmitting the second part of the extended PDSCH or the subframe transmitting the normal PDSCH or the next subframe to the subframe transmitting the shortened PDSCH, as shown in <FIG>. The DCI can contain an ending indicator (i.e., ending subframe boundary field) to indicate whether the ending time of the first PDSCH is the starting boundary or the ending boundary of the subframe transmitting the DCI and a length indicator to indicate the length of the first PDSCH.

Specially, for the ending subframe boundary field in DCI, one bit can be used to indicate the ending time (e.g., the ending subframe boundary) for example with respect to the subframe for sending the DCI in (E)PDCCH. For example, "<NUM>" indicates that the PDSCH ends at the starting boundary (<NUM>st subframe boundary in <FIG>) of the subframe sending the DCI, and "<NUM>" indicates that the PDSCH ends at the ending boundary(<NUM>nd subframe boundary in <FIG>) of the subframe sending the DCI.

For the length indicator for indicating the length of first PDSCH for example in terms of OFDM symbol, for example, <NUM> bits can be used to indicate the PDSCH length from <NUM> to <NUM> OFDM symbols. Alternatively, a reduced number of bits can be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate. For example, in the case that the DCI is transmitted in the subframe as shown in <FIG>, if the PDSCH ends at the starting boundary (<NUM>st subframe boundary in <FIG>) of the subframe sending the DCI, the length of the PDSCH can be only <NUM>-<NUM> symbols (shortened PDSCH), and if the PDSCH ends at the ending boundary (<NUM>nd subframe boundary in <FIG>) of the subframe sending the DCI, the length of the PDSCH can be only <NUM>-<NUM> symbols (normal PDSCH or extended PDSCH). In this case, a <NUM>-bit indicator can be used to indicate length of <NUM> to <NUM> OFDM symbols or length of <NUM> to <NUM> OFDM symbols, and the time period can be determined by the length indicator in connection with the ending indicator.

Due to regulation restriction on maximum burst length (e.g. maximum burst length < <NUM> in Japan) and/or the flexible burst starting time, it would lead to flexible burst ending time in order to utilize the maximum burst length allowed by regional regulation. When the last PDSCH of the burst would end at the middle of a subframe, shortened PDSCH in DwPTS could be directly used for flexible ending time in granularity of OFDM symbol. Alternatively, the shortened PDSCH and the previous one normal PDSCH can be scheduled together as an extended PDSCH by one DCI to one (group of) UE. The extended PDSCH or the shortened PDSCH is referred to the flexible last PDSCH of the burst.

<FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the fourth aspect of the present disclosure. As shown in <FIG>, in the unlicensed band, the last PDSCH of the burst is an extended PDSCH which includes a normal PDSCH part and a shorten PDSCH part. In order to indicate the time period of the last PDSCH of the burst in the unlicensed carrier, a DCI would be sent at PDCCH/EPDCCH of the licensed band. The DCI for the flexible last PDSCH of the burst (the last PDSCH of the burst as the flexible PDSCH) contains a length indicator to indicate the length of the last PDSCH, wherein the length starts from for example the starting boundary of the subframe transmitting the DCI. The DCI can optionally contain a starting indicator to indicate the starting time of the last PDSCH. However, since the starting boundary of the last PDSCH can be fixed to the starting boundary of the subframe sending the DCI as shown in <FIG>, the UE can know the starting of the last PDSCH, and therefore the starting indicator can be omitted. For the length indicator for indicating the length of first PDSCH for example in terms of OFDM symbol, for example, <NUM> bits can be used to indicate the PDSCH length from <NUM> to <NUM> OFDM symbols. Alternatively, a reduced number of bits (e.g. a <NUM>-bit indicator for length of <NUM>/<NUM>/<NUM>/<NUM> OFDM symbols, or a <NUM>-bit indicator for length of <NUM>/<NUM> OFDM symbols) can be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate.

The above method can also be applied to OFDM symbols with extended CP. In addition, if the last PDSCH of burst does not adopt the extended PDSCH but directly uses a shortened PDSCH, a similar DCI can be used to indicate the time period of the last shortened PDSCH, the only difference is that the length indicator for the shortened PDSCH indicates a length from <NUM>-<NUM> symbols in case of normal CP. In addition, the DCI for the shortened DCI can also be used for a normal PDSCH by indicating the length of <NUM> in case of normal CP.

In the fifth aspect, the selection between shortened and extended PDSCH for the last PDSCH of the burst can depend on scheduling strategy at eNB. And the same DCI format can be used for the shortened and extended PDSCH and optionally the normal PDSCH.

The scheduling strategy at eNB would consider one or more of following features:.

In order to indicate the time period of the last PDSCH of the burst in the unlicensed carrier, a DCI would be sent at PDCCH/EPDCCH of the licensed band. For example, <FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the fifth aspect of the present disclosure. As shown in <FIG>, two possible flexible last PDSCHs in the unlicensed band are illustrated, the upper one is an extended subframe and the bottom one is a shortened subframe. In order to uniformly indicate the time period of the two types of PDSCH in one DCI format, the DCI for the last PDSCH can be transmitted in the subframe starting to transmit the last PDSCH as shown in <FIG>. The DCI contains at least a length indicator to indicate the length of the last PDSCH, and can optionally contain a starting indicator to indicate the starting time of the last PDSCH. In the fifth aspect, since the starting boundary of the last PDSCH can be fixed to the starting boundary of the subframe sending the DCI as shown in <FIG>, the UE can know the starting of the last PDSCH, and therefore, the starting indicator can be omitted. For the length indicator for indicating the length of first PDSCH for example in terms of OFDM symbol, for example, <NUM> bits can be used to indicate the PDSCH length from <NUM> to <NUM> OFDM symbols. Alternatively, and according to the invention, a reduced number of bits (e.g. a <NUM>-bit indicator for length of <NUM>/<NUM>/<NUM>/(<NUM>+<NUM>) OFDM symbols) can be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate.

It is noted that the above method can also be applied to OFDM symbols with extended CP.

Based on the third aspect, whether the shortened PDSCH or the extended PDSCH will be scheduled for the first PDSCH in the burst would be selected depending on scheduling strategy at eNB, and one DCI format can be used to indicate both the types of PDSCH. In the fifth aspect, the selection between shortened and extended PDSCH for the last PDSCH of the burst can also depend on scheduling strategy at eNB, and both the types of PDSCH can also be indicated by one DCI format. In the sixth aspect, one DCI format can be used to indicate both the first and the last PDSCH for both the shortened PDSCH and the extended PDSCH. Here, there could be the following cases: <NUM>) shortened PDSCH in the beginning of the burst and shortened PDSCH in the last of the burst, <NUM>) shortened PDSCH in the beginning of the burst and extended PDSCH in the last of the burst, <NUM>) extended PDSCH in the beginning of the burst and shortened PDSCH in the last of the burst, and <NUM>) extended PDSCH in the beginning of the burst and extended PDSCH in the last of the burst. It is noted that, as a special case, the first and the last PDSCH can also be a normal PDSCH, and it can also be optionally indicated by the DCI defined in the sixth aspect. Whether the eNB uses a normal DCI or the DCI defined in the present disclosure for the normal PDSCH can be specified or configured.

<FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the sixth aspect of the present disclosure. As shown in <FIG>, three possible first PDSCHs and three possible last PDSCHs in the unlicensed band are illustrated, the first-row PDSCH is a shortened PDSCH as the first PDSCH, the second-row PDSCH is an extended PDSCH as the first PDSCH, the third-row PDSCH is a normal PDSCH as the first PDSCH, the fourth-row PDSCH is a shortened PDSCH as the last PDSCH, the fifth-row PDSCH is an extended PDSCH as the last PDSCH, and the sixth-row PDSCH is a normal PDSCH as the last PDSCH. The DCI for respectively scheduling these PDSCHs can be transmitted in the subframe transmitting the second part of the extended PDSCH or the subframe transmitting the normal PDSCH or the next subframe to the subframe transmitting the shortened PDSCH if the PDSCH is the first PDSCH and in the subframe starting to transmit the PDSCH if the PDSCH is the last PDSCH.

In order to uniformly indicate the time period of all these types of PDSCH in one DCI format, the DCI can contain a length indicator to indicate the length of the PDSCH and a starting-ending indicator to indicate the ending time of the PDSCH is the starting boundary of the subframe transmitting the DCI, or the ending time of the PDSCH is the ending boundary of the subframe transmitting the DCI, or the starting time of the PDSCH is the starting boundary of the subframe transmitting the DCI. In addition, the starting-ending indicator can also imply whether the PDSCH is the first PDSCH or the last PDSCH since the DCI for the first PDSCH indicates the ending time and the DCI for the last PDSCH indicates the starting time.

Specifically, for the starting-ending indicator, for example, <NUM> bits can be used to indicate the starting or ending subframe boundary for example with respect to the subframe of sending the DCI (PDCCH/EPDCCH). For example, "<NUM>" can be used to indicate the PDSCH ends at the starting boundary of the subframe sending the DCI (<NUM>st subframe boundary in <FIG>), "<NUM>" can be used to indicate the PDSCH ends at the ending subframe boundary of the subframe sending the DCI (<NUM>nd subframe boundary in <FIG>), and "<FIG>" can be used to indicate the PDSCH starts at the starting boundary of the subframe sending the DCI (<NUM>st subframe boundary in <FIG>).

For the length indicator for indicating the length of the PDSCH for example in terms of OFDM symbol, for example, <NUM> bits can be used to indicate the PDSCH length from <NUM> to <NUM> OFDM symbols. Alternatively, a reduced number of bits (e.g. a <NUM>-bit indicator for length of <NUM>/<NUM>/<NUM>/<NUM>/<NUM>/<NUM>/(<NUM>+<NUM>)/(<NUM>+<NUM>) OFDM symbols) can be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate.

In the seventh aspect, the eNB can transmit the first PDSCH of the burst starting with the first available OFDM symbol after the second carrier is occupied by the eNB with a fixed length, in particular with a length of a normal PDSCH. In other words, in the seventh aspect, the first PDSCH of the burst is a normal length PDSCH with a shifted starting symbol. After successful CCA in the unlicensed band, the eNB sends data in PDSCH which starts with the first OFDM symbol available for data transmission (in case of reservation signal such as preamble, RTS/CTS or PSS/SSS is sent after CCA ending) and ends with the OFDM symbol based on a fixed number of OFDM symbols.

In case of normal CP and no PDCCH region in the unlicensed band, a normal PDSCH consists of <NUM> OFDM symbols. The starting symbol of the first PDSCH is from the <NUM>st to <NUM>th depending on CCA ending time, while the ending time of PDSCH is from <NUM>th to <NUM>st if the length of the PDSCH keeps <NUM> OFDM symbols. In the seventh aspect, the first PDSCH of the burst starts and ends at a flexible time in terms of OFDM symbol boundary based on CCA ending.

<FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to the seventh aspect of the present disclosure. As shown in <FIG>, the eNB transmits the first PDSCH of the burst starting with the first available OFDM symbol after the second carrier is occupied by the eNB and the first PDSCH have a fixed length of one normal PDSCH. The normal length PDSCH with a shifted starting symbol (which can also be referred to as a flexible PDSCH) can reuse the structure of current normal PDSCH by for example entire shift or cyclic shift. The entire shift means that a normal PDSCH is entirely shifted to the flexible PDSCH such that the starting part of the normal PDSCH is shifted to the starting part of the flexible PDSCH and the ending part of the normal PDSCH is shifted to the ending part of the flexible PDSCH. The cyclic shift means that the front part of the flexible PDSCH comes from the rear part of a normal PDSCH and the rear part of the flexible PDSCH comes from the front part of the normal PDSCH, as shown in <FIG> which schematically illustrates an exemplary time sequence diagram for explaining the cyclic shift of the PDSCH according to the seventh aspect of the present disclosure.

In order to indicate the time period of the flexible first PDSCH of the burst in the unlicensed carrier, a DCI would be sent at PDCCH/EPDCCH of the licensed band. The DCI can be sent after or before the unlicensed channel is occupied by the eNB. For example, the DCI can be sent in the next subframe to the subframe starting transmission of the first PDSCH. In the example of <FIG>, the DCI is sent in the subframe transmitting the second part. The DCI for the first PDSCH contains an offset length indicator to indicate the offset length of the starting time of the first PDSCH with respect to a reference boundary and a reference boundary indicator to indicate whether the reference boundary is the starting time or the ending time of the subframe transmitting the DCI.

Specifically, for the reference boundary indicator, for example, one bit can be used to indicate a reference boundary for example with respect to the subframe sending the DCI (in PDCCH/EPDCCH). For example, "<NUM>" can be used to indicate the reference boundary is the starting boundary (<NUM>st subframe boundary in <FIG>) of the subframe sending the DCI, while "<NUM>" can be used to indicate the reference boundary is the ending boundary (<NUM>nd subframe boundary in <FIG>) of the subframe sending the DCI.

For the offset length indicator, for example, <NUM> bits can be used to indicate the PDSCH offset by <NUM> to <NUM> OFDM symbols before the reference boundary ("<NUM>" means no offset and the first PDSCH is a normal PDSCH). A reduced number of bits (e.g. <NUM>-bit indicator for length of <NUM>/<NUM>/<NUM>/<NUM> OFDM symbols) can be used in connection with a reduced set of possible starting positions in order to reduce signaling overhead as well as increase the robustness of the DCI due to the reduced coding rate.

Refer back to <FIG>, for the second PDSCH of the burst, a shortened PDSCH can be adopted to align with the subsequent subframe boundary. The shortened second PDSCH can be scheduled together or independently with the first PDSCH or the third PDSCH. If the shortened PDSCH is scheduled independently, the method of PDSCH&RS mapping and TBS determination in the first aspect can be used. If the shortened PDSCH is scheduled together with the first PDSCH or the third PDSCH as one extended PDSCH, the method of PDSCH&RS mapping and TBS determination in the second aspect can be used. It is noted that the second PDSCH and possibly subsequent PDSCHs of the bust may also adopt a shifted PDSCH with a fixed length. In this case, the scheduling method of the second PDSCH is the same as the shifted first PDSCH with the fixed length.

In addition, as another example of the seventh aspect, the first PDSCH is not necessarily a PDSCH with a fixed length, but can also be a PDSCH ending with the ending boundary of the subframe starting the first PDSCH (e.g. a shortened PDSCH) or a PDSCH end indicator to indicator to indicate the first PDSCH has a fixed length, or a PDSCH ending with the ending boundary of the next subframe to the subframe starting the first PDSCH (an extended PDSCH). <FIG> schematically illustrates an exemplary time sequence diagram for the licensed carrier and the unlicensed carrier according to this example of the seventh aspect of the present disclosure. In <FIG>, three possible first PDSCHs in the unlicensed band are illustrated. The upper PDSCH is a PDSCH with a fixed length of one normal PDSCH, the middle PDSCH is an extended PDSCH, and the bottom PDSCH is a shortened PDSCH. In order to uniformly indicate the time period of these first PDSCH, the DCI contains a PDSCH end indicator in addition to the above offset length indicator and reference boundary indicator. The PDSCH end indicator indicates the first PDSCH has a fixed length, the first PDSCH is a shortened PDSCH, or the first PDSCH is an extended PDSCH. For example, a <NUM>-bit indicator can be used to make such indication, e.g., "<NUM>" for the PDSCH with a fixed length, "<NUM>" for the shortened PDSCH, "<NUM>" for the extended PDSCH. When the first PDSCH is a shortened PDSCH, the offset length indicator indicates the length of the shortened PDSCH and the reference boundary indicator indicates the ending time of the shortened PDSCH. When the first PDSCH is an extended PDSCH, the offset length indicator indicates the length of the extended PDSCH minus one normal PDSCH length and the reference boundary indicator indicates the ending time of the first part (the shortened PDSCH part) of the extended PDSCH. It is noted that the DCI defined for this example can also be used for a normal PDSCH for example by setting the offset length to <NUM> for the PDSCH with a fixed length of one normal PDSCH length.

Similarly, the above method can also be applied to OFDM symbols with extended CP.

Claim 1:
A user equipment, UE, (<NUM>) comprising:
a receiving unit configured to receive (<NUM>) from an eNode B, eNB, (<NUM>), a downlink control information, DCI, in a first carrier, and to receive from the eNB a burst comprising at least a last flexible physical downlink shared channel, PDSCH, in a second carrier;
wherein the DCI is transmitted in a first subframe comprising <NUM> OFDM symbols,
wherein the last flexible PDSCH starts at one of subframe boundaries and ends at one of symbol boundaries in the first subframe and in a second subframe, the second subframe comprising <NUM> OFDM symbols and being consecutive to the first subframe,
wherein the DCI contains a length indicator to indicate a length of OFDM symbols of the last flexible PDSCH, by a reduced number of bits, wherein the reduced number of bits is less than <NUM> bits, which is necessary to indicate all lengths of <NUM> to <NUM> OFDM symbols.