WO2016008152A1 - Method and apparatus for special subframe transmission - Google Patents

Method and apparatus for special subframe transmission Download PDF

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Publication number
WO2016008152A1
WO2016008152A1 PCT/CN2014/082487 CN2014082487W WO2016008152A1 WO 2016008152 A1 WO2016008152 A1 WO 2016008152A1 CN 2014082487 W CN2014082487 W CN 2014082487W WO 2016008152 A1 WO2016008152 A1 WO 2016008152A1
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WO
WIPO (PCT)
Prior art keywords
special subframe
special
dmrss
configuration
symbols
Prior art date
Application number
PCT/CN2014/082487
Other languages
French (fr)
Inventor
Gang Wang
Original Assignee
Nec Corporation
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Publication date
Application filed by Nec Corporation filed Critical Nec Corporation
Priority to PCT/CN2014/082487 priority Critical patent/WO2016008152A1/en
Publication of WO2016008152A1 publication Critical patent/WO2016008152A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H04L5/0051—Allocation of pilot signals, i.e. of signals known to the receiver of dedicated pilots, i.e. pilots destined for a single user or terminal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1469—Two-way operation using the same type of signal, i.e. duplex using time-sharing

Definitions

  • Embodiments of the present invention generally relate to communication techniques. More particularly, embodiments of the present invention relate to a method and apparatus for special subframe transmission in a TDD system.
  • LTE and LTE- Advanced are aiming at creating a new series of specifications for the new evolving radio-access technology.
  • One of its goals is to go on improving the communication system performance, such as the higher throughput, and coverage enhancement.
  • LTE has two different duplex modes for separating the transmission directions from the user to the base station and back: frequency division duplex (FDD) and time division duplex (TDD).
  • FDD frequency division duplex
  • TDD time division duplex
  • a single bandwidth is shared between uplink (UL) and downlink (DL), with the sharing being performed by allotting different periods of time to uplink and downlink.
  • a frame may include 10 subframes, having several subframes allocated for uplink transmission (denoted as "U” in Figure 1), several other subframes allocated to downlink transmission (denoted as "D” in Figure 1). Those subframes allocated to uplink transmission or downlink transmission may also be called as normal subframes.
  • a special subframe is split into three parts: a part for downlink transmission (also called Downlink Pilot Time Slot (DwPTS)), a guard period (GP), and a part for uplink transmission (also called Uplink Pilot Time Slot (UpPTS)).
  • DwPTS Downlink Pilot Time Slot
  • GP guard period
  • UpPTS Uplink Pilot Time Slot
  • a user device in order to support and facilitate signal demodulation and detection on an uplink channel, a user device sends to a base station a reference signal known as the "Demodulation Reference Signal", DMRS, that the base station can use it to perform channel estimation.
  • DMRS Demodulation Reference Signal
  • a radio frame scheme with two slots for each subframe is used, and two DMRSs are typically transmitted in the uplink subframe, with one DMRS in each slot, as illustrated in Figure 2. This DMRS pattern works well for a normal uplink subframe with all symbols associated with uplink transmission.
  • embodiments of the invention provide a method for special subframe transmission in a TDD system, wherein there is at least one TDD UL-DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the method may comprise a step of configuring at least two of multiple symbols associated with uplink transmission in a special subframe with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • the method may also comprise a step of transmitting to a base station the special subframe configured with the at least two DMRSs.
  • embodiments of the invention provide a method for special subframe transmission in a TDD system, wherein there is at least one TDD UL-DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the method may comprise a step of receiving a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • embodiments of the invention provide an apparatus for special subframe transmission in a TDD system, wherein there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the apparatus may comprise a special subframe configuring unit configured to configure at least two of multiple symbols associated with uplink transmission in a special subframe with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • the apparatus may also comprise a special subframe transmitting unit configured to transmit to a base station the special subframe configured with the at least two DMRSs.
  • embodiments of the invention provide an apparatus for special subframe transmission in a TDD system, wherein there is at least one TDD UL-DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the apparatus may comprise a special subframe receiving configured to receive a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • Figure 1 shows a diagram schematically illustrating UL-DL configurations specified in a LTE TDD system
  • Figure 2 shows a diagram schematically illustrating frame structure type 2 with DMRS pattern specified in 3 GPP specifications;
  • Figure 3 illustrates a flow chart of a method in a user device for special subframe transmission in TDD system according to an example embodiment of the present invention
  • Figures 4(a) and 4(b) show diagrams schematically illustrating a special subframe with the DMRS pattern specified in 3 GPP specifications and with a DMRS pattern according to an example embodiment of the present invention
  • Figure 5 illustrates a flow chart of a method in a base station for special subframe transmission in TDD system according to an example embodiment of the present invention
  • Figure 6 illustrates a handshake diagram illustrating a process of special subframe transmission according to an example embodiment of the present invention
  • Figure 7 illustrates a block diagram of an apparatus for special subframe transmission in TDD system according to an example embodiment of the present invention.
  • Figure 8 illustrates block diagrams of an apparatus for special subframe transmission in TDD system according to an example embodiment of the present invention.
  • a reference signal called DMRS should be sent by a user device to a base station in order to support and facilitate signal demodulation and detection.
  • a special subframe is allocated for uplink data transmission, since only part of the special subframe is allocated for uplink data, generally only one DMRS, or some cases, no DMRS is specified in the part of the special subframe, which makes the DMRS -based channel estimation results undesirable.
  • symbol 3 and symbol 10 of a subframe each are configured with one DMRS.
  • a new DMRS pattern is proposed for the special subframe in embodiments of the present invention to improve the channel estimation and then reduce the block error ratio (BLER) of the uplink data demodulation based on channel estimation results.
  • BLER block error ratio
  • FIG. 3 illustrates a flow chart of a method 300 in a user device for special subframe transmission in TDD system according to an example embodiment of the present invention.
  • the TDD system there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3GPP specifications, which are shown in Figure 1.
  • other UL-DL configurations such as those specified by other organizations or by individual users may also be available as long as there is at least one special subframe included in the other UL-DL configurations.
  • a user device may be any type of mobile terminal, fixed terminal, or portable terminal including a mobile handset, station, unit, device, multimedia computer, multimedia tablet, Internet node, communicator, desktop computer, laptop computer, notebook computer, netbook computer, tablet computer, personal communication system (PCS) device, personal navigation device, personal digital assistants (PDAs), audio/video player, digital camera/camcorder, positioning device, television receiver, radio broadcast receiver, electronic book device, game device, or any combination thereof, including the accessories and peripherals of these devices, or any combination thereof.
  • PCS personal communication system
  • PDAs personal digital assistants
  • audio/video player digital camera/camcorder
  • positioning device television receiver, radio broadcast receiver, electronic book device, game device, or any combination thereof, including the accessories and peripherals of these devices, or any combination thereof.
  • step S301 where at least two of multiple symbols associated with uplink transmission in a special subframe are configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • a special subframe may consist of a plurality of symbols.
  • the number of symbols included in the special subframe is not limited in the present invention. In an example, as specified in 3GPP specifications, there are fourteen symbols in a special subframe, numbered from 0 to 13. It should be noted that there may be any other amount of symbols included in the special subframes, such as ten, twelve, twenty symbols, and so on. The scope of the present invention is not limited in this regard.
  • a special subframe is generally split into three parts, one for downlink transmission, called DwPTS, one for a guard period, and one for uplink transmission, called UpPTS. Each part may occupy one or more symbols.
  • DwPTS downlink transmission
  • UpPTS uplink transmission
  • Each part may occupy one or more symbols.
  • the special subframe is used for uplink transmission, generally only the UpPTS is available. Although only two symbols are allocated for uplink transmission as specified in current 3GPP specifications, more symbols may be configured for the UpPTS so that the special subframe may be used to carry uplink data in a more effective manner.
  • a special subframe when a special subframe is to be applied in TTI bundling with a normal uplink subframe, more than two symbols of the special subframe, such as five, seven or nine symbols, may be allocated for the uplink transmission, and then the remaining symbols are preserved for downlink transmission and the guard period. More symbol allocation manners for uplink transmission in a special subframe may be referred to the PCT application WO2014047788, which is published on April 3, 2014. It should be noted that the number of symbols associated with uplink transmission in the special subframe is not limited in the preset invention.
  • At least two DMRSs in one uplink subframe may guarantee a tolerable error of channel estimation. Therefore, in embodiments of the present invention, at least two of the multiple symbols associated with uplink transmission in the special subframe are configured with at least two DMRSs, wherein each of the at least two symbols is corresponding to one of the at least two DMRSs. That is, at least two of the multiple symbols associated with uplink transmission are selected to carry the DMRSs, and each of the selected symbols carries one DMRSs. For example, if there are seven symbols in a special subframe are associated with uplink transmission, then two of the seven symbols are configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
  • the number of symbols that are configured with the DMRSs is not limited, but may be less than the number of symbols associated with uplink transmission, since there shall be one or more symbols remained for carrying uplink data. For example, there may be two, three, four symbols configured with the DMRSs if there are six symbols associated with uplink transmission in a special subframe. According to embodiments of the present invention, the DMRSs in different symbols may be the same signal or different signals.
  • the special subframe may carry uplink data in at least one other of the multiple symbols. In one embodiment, all of the remaining symbols that are not configured with the DMRSs may be used for carrying uplink data. In some other embodiments, only one or some of the remaining symbols may be used for carrying uplink data.
  • the scope of the present invention is not limited in this regard.
  • the uplink data may be any data that the device user would like to transmit to the base station, and the scope of the present invention is not limited in this regard.
  • the number of symbols associated with the uplink transmission is limited and the remaining symbols except those configured with the DMRSs may be used for carrying uplink data, there is a tradeoff between the uplink data transmission rate and the channel estimation error.
  • two of the multiple symbols associated with uplink transmission in the special subframe may be configured with two DMRSs. In this case, a reasonable level of channel estimation may be guaranteed because of the two DRMSs, while more symbols may be preserved to carry uplink data, and the uplink data transmission rate may not be largely sacrificed.
  • the sparsity of DMRSs is helpful for channel estimations, there may be at least one other symbol between the at least two symbols.
  • the separation between the at least two symbols is not limited in the present invention.
  • some or all of the at least two symbols configured with the DMRSs may be successive.
  • symbol 7, symbol 10 and symbol 11 each may be configured with a DMRS, and there are two other symbols between symbols 7 and 10, and symbols 10 and 11 are successive symbols.
  • the placement of symbols that are configured with the DMRSs is not limited in embodiments of the present invention.
  • the special subframe in embodiments of the present invention is a special subframe specified in 3GPP specifications
  • one of the at least two symbol may be the eleventh symbol (symbol 10) of the special subframe, as the eleventh symbol is specified to carry a DMRS in 3GPP specifications.
  • the DMRS pattern proposed in the present invention may be applied to the current 3GPP LTE TDD system with minor changes.
  • the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs may be called a special DMRS configuration, compared with the current DMRS configuration specified in the 3GPP specifications.
  • a special DMRS configuration In an UL-DL configuration, there may be one or more special subframes.
  • the special DMRS configuration may be applied to all of the subframes or to only one or some of the subframes.
  • each of the two special subframes may be applied with the special DMRS configuration in some embodiments, or one of the two special subframes may be applied with the special DMRS configuration in some other embodiments.
  • Figures 4(a) and 4(b) each show a special subframe with seven symbols associated with uplink transmission.
  • the special subframe is configured with the DMRS pattern specified in 3 GPP specifications, and only the eleventh symbol, symbol 10, is configured with a DMRS, which may cause undesirable channel estimation.
  • Figure 4(b) shows a special subframe with a DMRS pattern according to an example embodiment of the present invention, wherein two symbols, symbol 5 and symbol 7, each is configured with a DMRS.
  • step S302 the special subframe configured with the at least two DMRSs is transmitted to a base station.
  • the special DMRS configuration may be enabled or disabled according to an indication from the base station.
  • an activation indication or a deactivation indication for the special DMRS configuration may be received from the base station.
  • the special DMRS configuration may be activated according to the activation indication, or may be deactivated according to the deactivation indication.
  • the activation or deactivation indication may be a one-bit message, where a bit "1" indicates that the special DMRS configuration will be activated, and a bit "0" indicates that the special DMRS configuration will be deactivated.
  • the activation or deactivation indication may occupy a number of bits. The length and format of the activation or deactivation indication are not limited in the present invention.
  • the user device may configure the special subframe with the normal DMRS configuration in some embodiments, that is, only the eleventh symbol in the special subframe is configured with a DMRS if this symbol is associated with uplink transmission.
  • an activation or deactivation indication may not be transmitted between the base station; and the user device may configure the special subframe based on the special DMRS configuration by default.
  • the user device may decide by its own whether the special DMRS configuration is enabled or not.
  • the user device may receive from the base station an indication for the placement of the DMRSs in the special subframe, the distance between each two DMRSs, and/or which special subframe to be specially configured. It should be noted that the user device may further receive any other indication for the DMRS configuration of the special subframe from the base station. The scope of the present invention is not limited in this regard.
  • FIG. 5 illustrates a flow chart of a method 500 in a base station for special subframe transmission in TDD system according to an example embodiment of the present invention.
  • the TDD system there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3GPP specifications, which are shown in Figure 1.
  • other UL-DL configurations such as those specified by other organizations or by individual users may also be available as long as there is at least one special subframe included in the other UL-DL configurations.
  • the method 500 may be carried out by, for example, an eNode B, a node B, a base station controller (BSC), a gateway, a relay, a server, or any other applicable device, all of which are collectively called a base station herein.
  • BSC base station controller
  • step S501 a special subframe is received from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • step S502 channel estimation for the received special subframe is performed according to the at least two DMRSs.
  • the channel estimation results may be used to demodulate the uplink data carried in the special subframe, or may be used for jointly channel estimation with other uplink subframe(s).
  • the channel estimation results may be improved and the BLRE of signal demodulation in the base station may be reduced.
  • the base station may utilize the at least two DMRSs in other ways.
  • the at least two DMRSs may be used by the base station to calculate the channel quality information.
  • the usage of the DMRSs in the base station is not limited in the present invention.
  • Figure 6 illustrates a handshake diagram illustrating a process 600 of special subframe transmission according to an example embodiment of the present invention.
  • the base station 11 may transmit an activation indication to the user device 10 to activate the special DMRS configuration.
  • step S602 the user device 10 may receive the activation indication and then may send an acknowledgement (ACK) to the base station 11.
  • ACK acknowledgement
  • NACK negative acknowledgement
  • the user device 10 may transmit a negative acknowledgement (NACK) to the base station 11.
  • the base station 11 may retransmit the activation indication to the user device upon receiving a NACK from the base station 10. That is, steps S601 and S602 may be repeated until the user device 10 has successfully received the activation indication.
  • the user device 10 may activate the special DMRS configuration and then configure the special subframe based on the special DMRS configuration in step S603.
  • step S604 the user device 10 may transmit the special subframe configured with at least two DMRSs and including uplink data to the base station 11.
  • the base station 11 may receive the special subframe and then may perform channel estimation for the special subframe according to the at least two DMRSs in step S605.
  • the steps S601-S605 shows a process of special subframe transmission when the special DMRS configuration is enabled. It should be noted that this process may be repeated for multiple times, or be repeated for multiple subframes in an UL-DL configuration.
  • the base station 11 may transmit a deactivation indication to the user device 10 in step S606 to deactivate the special DMRS configuration.
  • the user device 10 receives the deactivation indication and then may send an acknowledge message (ACK) to the base station 11 in step S607.
  • ACK acknowledge message
  • the user device 10 may transmit a negative acknowledgement (NACK) to the base station 11.
  • NACK negative acknowledgement
  • the base station 11 may retransmit the deactivation indication to the user device upon receiving a NACK from the base station 10. That is, steps S606 and S607 may be repeated until the user device 10 has successfully received the deactivation indication.
  • step S608 the user device 10 may deactivate the special DMRS configuration according to the deactivation indication.
  • the user device 10 may further configure the special subframe with the normal DMRS configuration when the special subframe is used for uplink transmission, that is, only the eleventh symbol in the special subframe is configured with a DMRS if this symbol is associated with uplink transmission.
  • steps in Figure 6 may be omitted, or one or more additional steps may be added in Figure 6.
  • steps S601, S602, S606, S607, and S608 may be omitted.
  • steps 602 and 603, or steps S607 and S608, may be performed in parallel.
  • steps in Figure 6 are not performed in sequence, and there may be one or more other steps not shown between the steps in Figure 6, or there may be a large time separation between any two steps in Figure 6.
  • the user device may wait for performing step S603 until there is uplink data needed to be transmitted.
  • Figure 7 illustrates a block diagram of an apparatus 700 for special subframe transmission in TDD system according to an example embodiment of the present invention, wherein there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the apparatus 700 may be a user device, or may be a part thereof.
  • the apparatus 700 may comprise a special subframe configuring unit 701 configured to configure at least two of multiple symbols associated with uplink transmission in a special subframe with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • the apparatus 700 may also comprise a special subframe transmitting unit 702 configured to transmit to a base station the special subframe configured with the at least two DMRSs.
  • the special subframe may carry uplink data in at least one other of the multiple symbols.
  • one of the at least two symbols may be the eleventh symbol of the special frame specified in 3GPP specifications.
  • two of the multiple symbols associated with uplink transmission in the special subframe may be configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
  • the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3 GPP specifications.
  • the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs may be a special DMRS configuration
  • the apparatus 700 may further comprise: a receiving unit configured to receive an activation indication or a deactivation indication for the special DMRS configuration from the base station; an activation unit configured to activate the special DMRS configuration according to the activation indication; and a deactivation unit configured to deactivate the special DMRS configuration according to the deactivation indication.
  • Figure 8 illustrates block diagrams of an apparatus 800 for special subframe transmission in TDD system according to an example embodiment of the present invention, wherein there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.
  • the apparatus may be a base station, or may be a part thereof.
  • the apparatus 800 may comprise a special subframe receiving unit 801 configured to receive a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
  • the special subframe may carry uplink data in at least one other of the multiple symbols.
  • one of the at least two symbols may be the eleventh symbol of the special frame specified in 3GPP specifications.
  • two of the multiple symbols associated with uplink transmission in the special subframe may be configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
  • the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3 GPP specifications.
  • the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs is a special DMRS configuration
  • the apparatus 800 may further comprise: a transmitting unit configured to transmit to the user device an activation indication or a deactivation indication for the special DMRS configuration, the activation indication indicating the user device to activate the special DMRS configuration, and the deactivation indication indicating the user device to deactivate the special DMRS configuration.
  • the apparatus 800 may further comprise a channel estimation performing unit configured to perform channel estimation for the received special subframe according to the at least two DMRSs.
  • Embodiments of the present invention may also be implemented as a computer program product, comprising at least one computer readable storage medium having a computer readable program code portion stored thereon.
  • the computer readable program code portion comprises at least codes for performing the method as illustrated in Figure 3 or Figure 5.
  • the apparatus 700 may be configured to implement functionalities as described with reference to Figure 3, and the apparatus 800 may be configured to implement functionalities as described with reference to Figure 5. Therefore, the features discussed with respect to method 300 may apply to the corresponding components of the apparatus 700, and the features discussed with respect to method 500 may apply to the corresponding components of the apparatus 800. It is further noted that the components of the apparatus 700 and the apparatus 800 may be embodied in hardware, software, firmware, and/or any combination thereof. For example, the components of the apparatus 700 or 800 may be respectively implemented by a circuit, a processor or any other appropriate selection device. Those skilled in the art will appreciate that the aforesaid examples are only for illustration not limitation.
  • the apparatus 700 comprises at least one processor.
  • the at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors already known or developed in the future.
  • the apparatus 700 further comprises at least one memory.
  • the at least one memory may include, for example, semiconductor memory devices, e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices.
  • the at least one memory may be used to store program of computer executable instructions.
  • the program can be written in any high-level and/or low-level compilable or interpretable programming languages.
  • the computer executable instructions may be configured, with the at least one processor, to cause the apparatus 700 to at least perform according to method 300 as discussed above.
  • the apparatus 800 comprises at least one processor.
  • the at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors already known or developed in the future.
  • the apparatus 800 further comprises at least one memory.
  • the at least one memory may include, for example, semiconductor memory devices, e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices.
  • the at least one memory may be used to store program of computer executable instructions.
  • the program can be written in any high-level and/or low-level compilable or interpretable programming languages.
  • the computer executable instructions may be configured, with the at least one processor, to cause the apparatus 800 to at least perform according to method 500 as discussed above.
  • the present disclosure may be embodied in an apparatus, a method, or a computer program product.
  • the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.
  • some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto.

Abstract

Embodiments of the invention provide a method for special subframe transmission in a Time Division Duplex (TDD) system, wherein there is at least one TDD uplink (UL)-downlink (DL) configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe.The method may comprise a step of configuring at least two of multiple symbols associated with uplink transmission in a special subframe with at least two Demodulation Reference Signals (DMRSs), each of the at least two symbols corresponding to one of the at least two DMRSs.The method may also comprise a step of transmitting to a base station the special subframe configured with the at least two DMRSs.

Description

METHOD AND APPARATUS FOR SPECIAL SUBFRAME TRANSMISSION
FIELD OF THE INVENTION
[0001] Embodiments of the present invention generally relate to communication techniques. More particularly, embodiments of the present invention relate to a method and apparatus for special subframe transmission in a TDD system.
BACKGROUND OF THE INVENTION
[0002] 3 GPP LTE and LTE- Advanced are aiming at creating a new series of specifications for the new evolving radio-access technology. One of its goals is to go on improving the communication system performance, such as the higher throughput, and coverage enhancement. LTE has two different duplex modes for separating the transmission directions from the user to the base station and back: frequency division duplex (FDD) and time division duplex (TDD). In the TDD duplex mode, a single bandwidth is shared between uplink (UL) and downlink (DL), with the sharing being performed by allotting different periods of time to uplink and downlink.
[0003] In LTE TDD system, there are 7 different patterns of TDD uplink/downlink switching, termed uplink-downlink (UL-DL) configurations 0 through 6, as illustrated in Figure 1. In each UL-DL configuration, a frame may include 10 subframes, having several subframes allocated for uplink transmission (denoted as "U" in Figure 1), several other subframes allocated to downlink transmission (denoted as "D" in Figure 1). Those subframes allocated to uplink transmission or downlink transmission may also be called as normal subframes. One or two special subframe (denoted as "S" in Figure 1) in the UL-DL configurations. A special subframe is split into three parts: a part for downlink transmission (also called Downlink Pilot Time Slot (DwPTS)), a guard period (GP), and a part for uplink transmission (also called Uplink Pilot Time Slot (UpPTS)).
[0004] In LTE TDD system, in order to support and facilitate signal demodulation and detection on an uplink channel, a user device sends to a base station a reference signal known as the "Demodulation Reference Signal", DMRS, that the base station can use it to perform channel estimation. In LTE TDD system, a radio frame scheme with two slots for each subframe is used, and two DMRSs are typically transmitted in the uplink subframe, with one DMRS in each slot, as illustrated in Figure 2. This DMRS pattern works well for a normal uplink subframe with all symbols associated with uplink transmission. However, when it comes to a special subframe, since only part of the special subframe is allocated for uplink transmission, only one DMRS, or some cases, no DMRS is transmitted from the user device to the base station, which makes the channel estimation results undesirable. Therefore, there is a need to find a solution for special subframe transmission with DMRS so as to support channel estimation for the special subframes. SUMMARY OF THE INVENTION
[0005] There is provided a method and apparatus for special subframe transmission in embodiments of the present invention. Specifically, embodiments of the present invention propose a solution for special subframe transmission in uplink with DMRS for channel estimation.
[0006] According to a first aspect of the present invention, embodiments of the invention provide a method for special subframe transmission in a TDD system, wherein there is at least one TDD UL-DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. The method may comprise a step of configuring at least two of multiple symbols associated with uplink transmission in a special subframe with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs. The method may also comprise a step of transmitting to a base station the special subframe configured with the at least two DMRSs.
[0007] According to a second aspect of the present invention, embodiments of the invention provide a method for special subframe transmission in a TDD system, wherein there is at least one TDD UL-DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. The method may comprise a step of receiving a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
[0008] According to a third aspect of the present invention, embodiments of the invention provide an apparatus for special subframe transmission in a TDD system, wherein there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. The apparatus may comprise a special subframe configuring unit configured to configure at least two of multiple symbols associated with uplink transmission in a special subframe with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs. The apparatus may also comprise a special subframe transmitting unit configured to transmit to a base station the special subframe configured with the at least two DMRSs.
[0009] According to a fourth aspect of the present invention, embodiments of the invention provide an apparatus for special subframe transmission in a TDD system, wherein there is at least one TDD UL-DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. The apparatus may comprise a special subframe receiving configured to receive a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
[0010] Other features and advantages of the embodiments of the present invention will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Through the following detailed description with reference to the accompanying drawings, the above and other objectives, features and advantages of embodiments of the present invention will become more comprehensible. In the drawings, several embodiments of the present invention will be illustrated in an example and non-limiting manner, wherein:
[0012] Figure 1 shows a diagram schematically illustrating UL-DL configurations specified in a LTE TDD system;
[0013] Figure 2 shows a diagram schematically illustrating frame structure type 2 with DMRS pattern specified in 3 GPP specifications; [0014] Figure 3 illustrates a flow chart of a method in a user device for special subframe transmission in TDD system according to an example embodiment of the present invention;
[0015] Figures 4(a) and 4(b) show diagrams schematically illustrating a special subframe with the DMRS pattern specified in 3 GPP specifications and with a DMRS pattern according to an example embodiment of the present invention;
[0016] Figure 5 illustrates a flow chart of a method in a base station for special subframe transmission in TDD system according to an example embodiment of the present invention;
[0017] Figure 6 illustrates a handshake diagram illustrating a process of special subframe transmission according to an example embodiment of the present invention;
[0018] Figure 7 illustrates a block diagram of an apparatus for special subframe transmission in TDD system according to an example embodiment of the present invention; and
[0019] Figure 8 illustrates block diagrams of an apparatus for special subframe transmission in TDD system according to an example embodiment of the present invention.
[0020] Throughout the drawings, the same or corresponding reference symbols refer to the same or corresponding parts.
DETAILED DESCRIPTION OF EMBODIMENTS
[0021] Principles of the present invention will now be described with reference to various example embodiments illustrated in the drawings. It should be appreciated that depiction of these embodiments is only to enable those skilled in the art to better understand and further implement the present invention, not intended for limiting the scope of the present invention in any manner.
[0022] As mentioned above, in uplink transmission, a reference signal called DMRS should be sent by a user device to a base station in order to support and facilitate signal demodulation and detection. In the case where a special subframe is allocated for uplink data transmission, since only part of the special subframe is allocated for uplink data, generally only one DMRS, or some cases, no DMRS is specified in the part of the special subframe, which makes the DMRS -based channel estimation results undesirable. For example, as specified in 3GPP specifications, for example, in 3GPP LTE Rel.8, symbol 3 and symbol 10 of a subframe each are configured with one DMRS. In the case where symbol 7 to symbol 13 of a special subframe are allocated for uplink transmission, only one DMRS that is configured in symbol 10 of the special subframe is transmitted to the base station. The inventors have found that at least two DMRSs in a subframe received from the user device can guarantee that the channel estimation results are with tolerable errors. If only one DMRS is transmitted to the base station, the channel estimation results for the special subframe are undesirable.
[0023] In order to address the above and other potential problems, a new DMRS pattern is proposed for the special subframe in embodiments of the present invention to improve the channel estimation and then reduce the block error ratio (BLER) of the uplink data demodulation based on channel estimation results.
[0024] Reference is first made to Figure 3, which illustrates a flow chart of a method 300 in a user device for special subframe transmission in TDD system according to an example embodiment of the present invention. In the TDD system, there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. In some embodiments, the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3GPP specifications, which are shown in Figure 1. In some other embodiments, other UL-DL configurations, such as those specified by other organizations or by individual users may also be available as long as there is at least one special subframe included in the other UL-DL configurations.
[0025] As used herein, a user device may be any type of mobile terminal, fixed terminal, or portable terminal including a mobile handset, station, unit, device, multimedia computer, multimedia tablet, Internet node, communicator, desktop computer, laptop computer, notebook computer, netbook computer, tablet computer, personal communication system (PCS) device, personal navigation device, personal digital assistants (PDAs), audio/video player, digital camera/camcorder, positioning device, television receiver, radio broadcast receiver, electronic book device, game device, or any combination thereof, including the accessories and peripherals of these devices, or any combination thereof.
[0026] After start, the method 300 proceeds to step S301, where at least two of multiple symbols associated with uplink transmission in a special subframe are configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
[0027] Typically a special subframe may consist of a plurality of symbols. The number of symbols included in the special subframe is not limited in the present invention. In an example, as specified in 3GPP specifications, there are fourteen symbols in a special subframe, numbered from 0 to 13. It should be noted that there may be any other amount of symbols included in the special subframes, such as ten, twelve, twenty symbols, and so on. The scope of the present invention is not limited in this regard.
[0028] A special subframe is generally split into three parts, one for downlink transmission, called DwPTS, one for a guard period, and one for uplink transmission, called UpPTS. Each part may occupy one or more symbols. When the special subframe is used for uplink transmission, generally only the UpPTS is available. Although only two symbols are allocated for uplink transmission as specified in current 3GPP specifications, more symbols may be configured for the UpPTS so that the special subframe may be used to carry uplink data in a more effective manner. For example, when a special subframe is to be applied in TTI bundling with a normal uplink subframe, more than two symbols of the special subframe, such as five, seven or nine symbols, may be allocated for the uplink transmission, and then the remaining symbols are preserved for downlink transmission and the guard period. More symbol allocation manners for uplink transmission in a special subframe may be referred to the PCT application WO2014047788, which is published on April 3, 2014. It should be noted that the number of symbols associated with uplink transmission in the special subframe is not limited in the preset invention.
[0029] As mentioned above, at least two DMRSs in one uplink subframe may guarantee a tolerable error of channel estimation. Therefore, in embodiments of the present invention, at least two of the multiple symbols associated with uplink transmission in the special subframe are configured with at least two DMRSs, wherein each of the at least two symbols is corresponding to one of the at least two DMRSs. That is, at least two of the multiple symbols associated with uplink transmission are selected to carry the DMRSs, and each of the selected symbols carries one DMRSs. For example, if there are seven symbols in a special subframe are associated with uplink transmission, then two of the seven symbols are configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs. In embodiments of the present invention, the number of symbols that are configured with the DMRSs is not limited, but may be less than the number of symbols associated with uplink transmission, since there shall be one or more symbols remained for carrying uplink data. For example, there may be two, three, four symbols configured with the DMRSs if there are six symbols associated with uplink transmission in a special subframe. According to embodiments of the present invention, the DMRSs in different symbols may be the same signal or different signals.
[0030] In some embodiments, the special subframe may carry uplink data in at least one other of the multiple symbols. In one embodiment, all of the remaining symbols that are not configured with the DMRSs may be used for carrying uplink data. In some other embodiments, only one or some of the remaining symbols may be used for carrying uplink data. The scope of the present invention is not limited in this regard. The uplink data may be any data that the device user would like to transmit to the base station, and the scope of the present invention is not limited in this regard.
[0031] As the number of symbols associated with the uplink transmission is limited and the remaining symbols except those configured with the DMRSs may be used for carrying uplink data, there is a tradeoff between the uplink data transmission rate and the channel estimation error. In one embodiment of the present invention, two of the multiple symbols associated with uplink transmission in the special subframe may be configured with two DMRSs. In this case, a reasonable level of channel estimation may be guaranteed because of the two DRMSs, while more symbols may be preserved to carry uplink data, and the uplink data transmission rate may not be largely sacrificed.
[0032] According to some embodiments of the present invention, since the sparsity of DMRSs is helpful for channel estimations, there may be at least one other symbol between the at least two symbols. The separation between the at least two symbols is not limited in the present invention. In an embodiment, there may be two other symbols between the at least two symbols. In some embodiments, there may be at least one other symbol between each two of the at least two symbols. In some other embodiments, some or all of the at least two symbols configured with the DMRSs may be successive. As an example, for a special subframe having symbol 7 to symbol 13 associated with uplink transmission, symbol 7, symbol 10 and symbol 11 each may be configured with a DMRS, and there are two other symbols between symbols 7 and 10, and symbols 10 and 11 are successive symbols. The placement of symbols that are configured with the DMRSs is not limited in embodiments of the present invention.
[0033] If the special subframe in embodiments of the present invention is a special subframe specified in 3GPP specifications, one of the at least two symbol may be the eleventh symbol (symbol 10) of the special subframe, as the eleventh symbol is specified to carry a DMRS in 3GPP specifications. In this case, the DMRS pattern proposed in the present invention may be applied to the current 3GPP LTE TDD system with minor changes.
[0034] The configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs may be called a special DMRS configuration, compared with the current DMRS configuration specified in the 3GPP specifications. In an UL-DL configuration, there may be one or more special subframes. In this case, the special DMRS configuration may be applied to all of the subframes or to only one or some of the subframes. For example, there are two special subframes, subframes 1 and 6, in UL-DL configuration 2 as illustrated in Figure 1. In this case, each of the two special subframes may be applied with the special DMRS configuration in some embodiments, or one of the two special subframes may be applied with the special DMRS configuration in some other embodiments.
[0035] Figures 4(a) and 4(b) each show a special subframe with seven symbols associated with uplink transmission. In Figure 4(a), the special subframe is configured with the DMRS pattern specified in 3 GPP specifications, and only the eleventh symbol, symbol 10, is configured with a DMRS, which may cause undesirable channel estimation. Figure 4(b) shows a special subframe with a DMRS pattern according to an example embodiment of the present invention, wherein two symbols, symbol 5 and symbol 7, each is configured with a DMRS.
[0036] The method 300 then proceeds to step S302, where the special subframe configured with the at least two DMRSs is transmitted to a base station.
[0037] The special DMRS configuration may be enabled or disabled according to an indication from the base station. In some embodiments of the present invention, before configuring the special subframe according to the method 300, an activation indication or a deactivation indication for the special DMRS configuration may be received from the base station. Then, the special DMRS configuration may be activated according to the activation indication, or may be deactivated according to the deactivation indication. In one example, the activation or deactivation indication may be a one-bit message, where a bit "1" indicates that the special DMRS configuration will be activated, and a bit "0" indicates that the special DMRS configuration will be deactivated. In other examples, the activation or deactivation indication may occupy a number of bits. The length and format of the activation or deactivation indication are not limited in the present invention.
[0038] When the special DMRS configuration is deactivated, the user device may configure the special subframe with the normal DMRS configuration in some embodiments, that is, only the eleventh symbol in the special subframe is configured with a DMRS if this symbol is associated with uplink transmission. In some embodiments, an activation or deactivation indication may not be transmitted between the base station; and the user device may configure the special subframe based on the special DMRS configuration by default. In some other embodiments, the user device may decide by its own whether the special DMRS configuration is enabled or not.
[0039] In some embodiments, the user device may receive from the base station an indication for the placement of the DMRSs in the special subframe, the distance between each two DMRSs, and/or which special subframe to be specially configured. It should be noted that the user device may further receive any other indication for the DMRS configuration of the special subframe from the base station. The scope of the present invention is not limited in this regard.
[0040] Reference is now made to Figure 5, which illustrates a flow chart of a method 500 in a base station for special subframe transmission in TDD system according to an example embodiment of the present invention. In the TDD system, there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. In some embodiments, the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3GPP specifications, which are shown in Figure 1. In some other embodiments, other UL-DL configurations, such as those specified by other organizations or by individual users may also be available as long as there is at least one special subframe included in the other UL-DL configurations.
[0041] According to embodiments of the present invention, the method 500 may be carried out by, for example, an eNode B, a node B, a base station controller (BSC), a gateway, a relay, a server, or any other applicable device, all of which are collectively called a base station herein.
[0042] After start, the method 500 proceeds to step S501, where a special subframe is received from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
[0043] The detailed DMRS configuration of the special subframe is discussed above and is omitted here.
[0044] The method 500 proceeds to step S502, where channel estimation for the received special subframe is performed according to the at least two DMRSs. It should be noted that any known approach of channel estimation based on reference signals may be used here. In some embodiments, the channel estimation results may be used to demodulate the uplink data carried in the special subframe, or may be used for jointly channel estimation with other uplink subframe(s). As the channel estimation for the special subframe is based on at least two DMRSs in the special subframe, the channel estimation results may be improved and the BLRE of signal demodulation in the base station may be reduced.
[0045] Except for or in addition to performing the channel estimation in step S502, the base station may utilize the at least two DMRSs in other ways. For example, the at least two DMRSs may be used by the base station to calculate the channel quality information. The usage of the DMRSs in the base station is not limited in the present invention.
[0046] Figure 6 illustrates a handshake diagram illustrating a process 600 of special subframe transmission according to an example embodiment of the present invention.
[0047] In step S601, the base station 11 may transmit an activation indication to the user device 10 to activate the special DMRS configuration.
[0048] In step S602, the user device 10 may receive the activation indication and then may send an acknowledgement (ACK) to the base station 11. In some other embodiments, if the activation indication is not received by the user device 10 successfully, the user device 10 may transmit a negative acknowledgement (NACK) to the base station 11. The base station 11 may retransmit the activation indication to the user device upon receiving a NACK from the base station 10. That is, steps S601 and S602 may be repeated until the user device 10 has successfully received the activation indication.
[0049] The user device 10 may activate the special DMRS configuration and then configure the special subframe based on the special DMRS configuration in step S603.
[0050] The process then proceeds to step S604, where the user device 10 may transmit the special subframe configured with at least two DMRSs and including uplink data to the base station 11.
[0051] The base station 11 may receive the special subframe and then may perform channel estimation for the special subframe according to the at least two DMRSs in step S605.
[0052] The steps S601-S605 shows a process of special subframe transmission when the special DMRS configuration is enabled. It should be noted that this process may be repeated for multiple times, or be repeated for multiple subframes in an UL-DL configuration.
[0053] If the base station 11 decides to deactivate the special DMRS configuration, for example, based on the channel quality, it may transmit a deactivation indication to the user device 10 in step S606 to deactivate the special DMRS configuration. The user device 10 receives the deactivation indication and then may send an acknowledge message (ACK) to the base station 11 in step S607. In some other embodiments, if the deactivation indication is not received by the user device 10 successfully, the user device 10 may transmit a negative acknowledgement (NACK) to the base station 11. The base station 11 may retransmit the deactivation indication to the user device upon receiving a NACK from the base station 10. That is, steps S606 and S607 may be repeated until the user device 10 has successfully received the deactivation indication.
[0054] The process then proceeds to step S608, where the user device 10 may deactivate the special DMRS configuration according to the deactivation indication. In this case, the user device 10 may further configure the special subframe with the normal DMRS configuration when the special subframe is used for uplink transmission, that is, only the eleventh symbol in the special subframe is configured with a DMRS if this symbol is associated with uplink transmission.
[0055] It should be noted that one or more steps in Figure 6 may be omitted, or one or more additional steps may be added in Figure 6. For example, one or more of steps S601, S602, S606, S607, and S608 may be omitted. It is to be noted that the order of steps illustrated in Figure 6 may be changed. For example, steps 602 and 603, or steps S607 and S608, may be performed in parallel. It also be noted that the steps in Figure 6 are not performed in sequence, and there may be one or more other steps not shown between the steps in Figure 6, or there may be a large time separation between any two steps in Figure 6. For example, after receiving an activation indication from the base station and sending an ACK to the base station, the user device may wait for performing step S603 until there is uplink data needed to be transmitted.
[0056] Figure 7 illustrates a block diagram of an apparatus 700 for special subframe transmission in TDD system according to an example embodiment of the present invention, wherein there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. The apparatus 700 may be a user device, or may be a part thereof.
[0057] As shown, the apparatus 700 may comprise a special subframe configuring unit 701 configured to configure at least two of multiple symbols associated with uplink transmission in a special subframe with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs. The apparatus 700 may also comprise a special subframe transmitting unit 702 configured to transmit to a base station the special subframe configured with the at least two DMRSs.
[0058] In some embodiments, there may be at least one other symbol between the at least two symbols. In some embodiments, the special subframe may carry uplink data in at least one other of the multiple symbols.
[0059] In some embodiments, one of the at least two symbols may be the eleventh symbol of the special frame specified in 3GPP specifications. In some embodiments, two of the multiple symbols associated with uplink transmission in the special subframe may be configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs. In some embodiments, the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3 GPP specifications.
[0060] In some embodiments, the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs may be a special DMRS configuration, and wherein the apparatus 700 may further comprise: a receiving unit configured to receive an activation indication or a deactivation indication for the special DMRS configuration from the base station; an activation unit configured to activate the special DMRS configuration according to the activation indication; and a deactivation unit configured to deactivate the special DMRS configuration according to the deactivation indication.
[0061] Figure 8 illustrates block diagrams of an apparatus 800 for special subframe transmission in TDD system according to an example embodiment of the present invention, wherein there is at least one TDD UL- DL configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe. The apparatus may be a base station, or may be a part thereof.
[0062] As shown, the apparatus 800 may comprise a special subframe receiving unit 801 configured to receive a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two DMRSs, each of the at least two symbols corresponding to one of the at least two DMRSs.
[0063] In some embodiments, there may be at least one other symbol between the at least two symbols. In some embodiments, the special subframe may carry uplink data in at least one other of the multiple symbols.
[0064] In some embodiments, one of the at least two symbols may be the eleventh symbol of the special frame specified in 3GPP specifications. In some embodiments, two of the multiple symbols associated with uplink transmission in the special subframe may be configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs. In some embodiments, the at least one UL-DL configuration may comprise UL-DL configurations 0 to 6 specified in 3 GPP specifications.
[0065] In some embodiments, the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs is a special DMRS configuration, and wherein the apparatus 800 may further comprise: a transmitting unit configured to transmit to the user device an activation indication or a deactivation indication for the special DMRS configuration, the activation indication indicating the user device to activate the special DMRS configuration, and the deactivation indication indicating the user device to deactivate the special DMRS configuration.
[0066] In some embodiments, the apparatus 800 may further comprise a channel estimation performing unit configured to perform channel estimation for the received special subframe according to the at least two DMRSs.
[0067] Embodiments of the present invention may also be implemented as a computer program product, comprising at least one computer readable storage medium having a computer readable program code portion stored thereon. In such embodiments, the computer readable program code portion comprises at least codes for performing the method as illustrated in Figure 3 or Figure 5.
[0068] It is noted that the apparatus 700 may be configured to implement functionalities as described with reference to Figure 3, and the apparatus 800 may be configured to implement functionalities as described with reference to Figure 5. Therefore, the features discussed with respect to method 300 may apply to the corresponding components of the apparatus 700, and the features discussed with respect to method 500 may apply to the corresponding components of the apparatus 800. It is further noted that the components of the apparatus 700 and the apparatus 800 may be embodied in hardware, software, firmware, and/or any combination thereof. For example, the components of the apparatus 700 or 800 may be respectively implemented by a circuit, a processor or any other appropriate selection device. Those skilled in the art will appreciate that the aforesaid examples are only for illustration not limitation.
[0069] In some embodiments of the present disclosure, the apparatus 700 comprises at least one processor. The at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors already known or developed in the future. The apparatus 700 further comprises at least one memory. The at least one memory may include, for example, semiconductor memory devices, e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices. The at least one memory may be used to store program of computer executable instructions. The program can be written in any high-level and/or low-level compilable or interpretable programming languages. In accordance with embodiments, the computer executable instructions may be configured, with the at least one processor, to cause the apparatus 700 to at least perform according to method 300 as discussed above.
[0070] In some embodiments of the present disclosure, the apparatus 800 comprises at least one processor. The at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors already known or developed in the future. The apparatus 800 further comprises at least one memory. The at least one memory may include, for example, semiconductor memory devices, e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices. The at least one memory may be used to store program of computer executable instructions. The program can be written in any high-level and/or low-level compilable or interpretable programming languages. In accordance with embodiments, the computer executable instructions may be configured, with the at least one processor, to cause the apparatus 800 to at least perform according to method 500 as discussed above.
[0071] Based on the above description, the skilled in the art would appreciate that the present disclosure may be embodied in an apparatus, a method, or a computer program product. In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
[0072] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any disclosure or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular disclosures. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.
[0073] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.
[0074] Various modifications, adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. Any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure. Furthermore, other embodiments of the disclosures set forth herein will come to mind to one skilled in the art to which these embodiments of the disclosure pertain 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 appended claims. Although specific terms are used herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED IS:
1. A method for special subframe transmission in a Time Division Duplex (TDD) system, wherein there is at least one TDD uplink (UL)-downlink (DL) configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe, and wherein the method comprises:
configuring at least two of multiple symbols associated with uplink transmission in a special subframe with at least two Demodulation Reference Signals (DMRSs), each of the at least two symbols corresponding to one of the at least two DMRSs; and
transmitting to a base station the special subframe configured with the at least two DMRSs.
2. The method according to claim 1, wherein there is at least one other symbol between the at least two symbols, and
wherein the special subframe carries uplink data in at least one other of the multiple symbols.
3. The method according to claim 1 or 2, wherein one of the at least two symbols is the eleventh symbol of the special frame specified in 3 GPP specifications.
4. The method according to claim 1 or 2, wherein two of the multiple symbols associated with uplink transmission in the special subframe are configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
5. The method according to claim 1 or 2, wherein the at least one UL-DL configuration comprises UL-DL configurations 0 to 6 specified in 3 GPP specifications.
6. The method according to claim 1 or 2, wherein the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs is a special DMRS configuration, and wherein the method further comprises: receiving an activation indication or a deactivation indication for the special DMRS configuration from the base station; and
activating the special DMRS configuration according to the activation indication, or deactivating the special DMRS configuration according to the deactivation indication.
7. A method for special subframe transmission in Time Division Duplex (TDD) system, wherein there is at least one TDD uplink (UL)-downlink (DL) configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe, and wherein the method comprises:
receiving a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two Demodulation Reference Signals (DMRSs), each of the at least two symbols corresponding to one of the at least two DMRSs.
8. The method according to claim 7, wherein there is at least one other symbol between the at least two symbols, and
wherein the received special subframe carries uplink data in at least one other of the multiple symbols.
9. The method according to claim 7 or 8, wherein one of the at least two symbols is the eleventh symbol of the special frame specified in 3GPP specifications.
10. The method according to claim 7 or 8, wherein two of the multiple symbols associated with uplink transmission in the special subframe are configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
1 1 . The method according to claim 7 or 8, wherein the at least one UL-DL configuration comprises UL-DL configurations 0 to 6 specified in 3GPP specifications.
12. The method according to claim 7 or 8, the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs is a special DMRS configuration, and wherein the method further comprises:
transmitting to the user device an activation indication or a deactivation indication for the special DMRS configuration, the activation indication indicating the user device to activate the special DMRS configuration, and the deactivation indication indicating the user device to deactivate the special DMRS configuration.
13. The method according to claim 7 or 8, further comprising:
performing channel estimation for the received special subframe according to the at least two DMRSs.
14. An apparatus for special subframe transmission in a Time Division Duplex (TDD) system, wherein there is at least one TDD uplink (UL)-downlink (DL) configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe, and wherein the apparatus comprises:
a special subframe configuring unit configured to configure at least two of multiple symbols associated with uplink transmission in a special subframe with at least two Demodulation Reference Signals (DMRSs), each of the at least two symbols corresponding to one of the at least two DMRSs; and
a special subframe transmitting unit configured to transmit to a base station the special subframe configured with the at least two DMRSs.
15. The apparatus according to claim 14, wherein there is at least one other symbol between the at least two symbols, and
wherein the special subframe carries uplink data in at least one other of the multiple symbols.
16. The apparatus according to claim 14 or 15, wherein one of the at least two symbols is the eleventh symbol of the special frame specified in 3 GPP specifications.
17. The apparatus according to claim 14 or 15, wherein two of the multiple symbols associated with uplink transmission in the special subframe are configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
18. The apparatus according to claim 14 or 15, wherein the at least one UL-DL configuration comprises UL-DL configurations 0 to 6 specified in 3 GPP specifications.
19. The apparatus according to claim 14 or 15, wherein the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs is a special DMRS configuration, and wherein the apparatus further comprises:
a receiving unit configured to receive an activation indication or a deactivation indication for the special DMRS configuration from the base station;
an activation unit configured to activate the special DMRS configuration according to the activation indication; and
a deactivation unit configured to deactivate the special DMRS configuration according to the deactivation indication.
20. An apparatus for special subframe transmission in Time Division Duplex (TDD) system, wherein there is at least one TDD uplink (UL)-downlink (DL) configuration in the TDD system, and the at least one UL-DL configuration comprises at least one special subframe, and wherein the apparatus comprises:
a special subframe receiving unit configured to receive a special subframe from a user device, at least two of multiple symbols associated with uplink transmission in the received special subframe being configured with at least two Demodulation Reference Signals (DMRSs), each of the at least two symbols corresponding to one of the at least two DMRSs.
21. The apparatus according to claim 20, wherein there is at least one other symbol between the at least two symbols, and wherein the received special subframe carries uplink data in at least one other of the multiple symbols.
22. The apparatus according to claim 20 or 21, wherein one of the at least two symbols is the eleventh symbol of the special frame specified in 3 GPP specifications.
23. The apparatus according to claim 20 or 21, wherein two of the multiple symbols associated with uplink transmission in the special subframe are configured with two DMRSs, each of the two symbols corresponding to one of the two DMRSs.
24. The apparatus according to claim 20 or 21, wherein the at least one UL-DL configuration comprises UL-DL configurations 0 to 6 specified in 3 GPP specifications.
25. The apparatus according to claim 20 or 21, the configuration of at least two of multiple symbols associated with uplink transmission in the special subframe with the at least two DMRSs is a special DMRS configuration, and wherein the apparatus further comprises:
a transmitting unit configured to transmit to the user device an activation indication or a deactivation indication for the special DMRS configuration, the activation indication indicating the user device to activate the special DMRS configuration, and the deactivation indication indicating the user device to deactivate the special DMRS configuration.
26. The apparatus according to claim 20 or 21, further comprising:
a channel estimation performing unit configured to perform channel estimation for the received special subframe according to the at least two DMRSs.
PCT/CN2014/082487 2014-07-18 2014-07-18 Method and apparatus for special subframe transmission WO2016008152A1 (en)

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