JP5855181B2 - How the user equipment performs and the user equipment - Google Patents

Description

The present invention relates to a communication technique, particularly, a method of user equipment to perform, and relates to user Ikuippumen bets.

  3GPP LTE and LTE-Advanced, known as development standards for the highly successful GSM / HSPA technology, are aimed at establishing a new specification series of new radio access technologies that continue to evolve. One of the goals is to realize further performance improvement of the cellular communication system by improving the throughput and low delay in packet transmission. In LTE releases 8 to 10, the throughput performance of the cell edge UE is vulnerable to the problem of low signal strength and strong inter-cell interference from neighboring cells. Also, since most of this type of UE is far away from the serving base station (eg, eNB) site, the received signal strength is attenuated by path loss. Furthermore, due to the characteristic of LTE being a single frequency network (SFN) that all cells in the system use the same frequency band to transmit downlink data, the UE receives strong interference from neighboring cells. .

  In order to solve these problems, two kinds of improvement methods were proposed to the 3GPP standardization group. One way is to increase the received signal strength of the cell edge UE by introducing small cells such as femtocells, picocells, repeaters. This is also called a heterogeneous network (HetNet). Another method is to reduce inter-cell interference through interference control. This method includes eICIC (enhanced inter-cell interference control) standardized in 3GPP Release 10, CoMP (multi-cell coordinated transmission / reception) standardized in 3GPP Release 11, and the like.

  The concept that forms the core of CoMP is that “in downlink data transmission, a cell edge UE usually receives data signals simultaneously from a plurality of eNBs including its serving eNB and neighboring cells eNB”. In general, a signal received from a neighboring cell is regarded as inter-cell interference, which adversely affects the UE's ability to successfully decode data information. In CoMP, signals transmitted from multiple cells are coordinated to mitigate the original interference.

  A typical CoMP network structure includes a central unit (CU) that connects all eNBs in the system via fiber or cable. Each eNB, also called a “cooperative eNB”, operates as a serving eNB for several UEs in each cell. In the case of a cell edge UE, data signals can be received from a plurality of eNBs via a radio interface. These eNBs form a cooperative set, and a UE that receives data information from an eNB that belongs to the cooperative set is referred to as a “CoMP UE” (hereinafter also referred to as “UE” for simplicity).

  In such a network, the CU emphasizes and controls the eNB in the cooperative set, and transmits a data packet to the CoMP UE. The CU first transmits the multi-cell scheduling result together with the data packet to the eNB in the cooperative set. The eNBs in the cooperative set are responsible for jointly transmitting data information to the CoMP UE. On the UE side, data information sent from a plurality of eNBs is combined to improve the quality of the received signal, so that the data information received by the CoMP UE has high reliability.

  In the LTE system, HARQ is always used in the system in order to improve the reliability of packet reception. HARQ plays an important role in maximizing spectral efficiency when packet transmission errors occur. The concept of HARQ is as follows. That is, when the packet reception by the UE is successful, the UE transmits an ACK packet to the central apparatus. In the case of failure, the UE transmits a NACK packet to the central device and instructs the central device to retransmit the packet that has failed to be received.

A conventional CoMP UE typically includes a HARQ combiner, a channel decoder, a CRC detector, and a feedback transmitter. In the conventional communication block of the HARQ process at the CoMP UE, demodulated data bits are transmitted to the HARQ combiner. The HARQ combiner combines multiple retransmission bits with different redundancy versions (RV) of the same packet for channel decoding. RV specifies the starting point of retransmission bits in the original transmission packet, and this information allows the HARQ combiner to combine these retransmission bits into previously transmitted packets. This combining method is an implementation issue, and manufacturers typically accomplish this using either a tracking combining (CC) scheme or an incremental redundancy (IR) scheme.
The channel decoder decodes the combined data bits and sends the decoded bits to the CRC detector. The CRC detector calculates the CRC value of the decoded packet and compares it with the CRC information carried in the original data packet. Thus, the CRC detector determines whether or not the reception of the packet is successful, and transmits the determination result to the feedback transmitter. The feedback transmitter transmits an ACK packet to the scheduler of the central apparatus when the reception of the packet is successful, and transmits a NACK when it is not successful. If a NACK is received by the central unit and the number of retransmission attempts has not reached the upper limit of the number of retransmissions, the corresponding packet is retransmitted to the UE, and the number of retransmission attempts is incremented by one.

  In the conventional CoMP HARQ operation, the same number of eNBs as the eNBs included in the CoMP cooperative set transmit retransmission packets to the CoMP UE. However, when restoring packet information in a CoMP UE by packet retransmission, only some eNBs in the CoMP cooperating set may be sufficient, and in that case, all eNBs in the cooperating set should be used. Results in wasted valuable radio resources.

  In view of the above-described problem, in the technology, among the base stations in the cooperative set, the next packet retransmission is performed using a sufficient number of base station subsets to restore the packet information from the retransmission data. What is needed is a method and apparatus for enhancing downlink HARQ functionality.

  According to a first aspect of the present invention, an embodiment of the present invention provides a method performed by a user equipment in a communication system. The method estimates the channel quality required for the next packet retransmission in response to a packet reception failure, selects a target subset of base stations from a coordinated set of base stations based on the required channel quality, An indication of the target subset of the base station is transmitted to the central unit.

  According to a second aspect of the present invention, an embodiment of the present invention provides a method performed by a central unit in a communication system. In response to a packet reception failure, the method selects a base station object for the next retransmission, selected from a coordinated set of base stations based on the estimated channel quality required for the next packet retransmission. It receives the indication of the subset, and notifies the base station in the target subset to retransmit the packet to the user equipment.

  According to a third aspect of the present invention, embodiments of the present invention provide user equipment. In response to a packet reception failure, the user equipment includes an estimation device that estimates a channel quality required for the next packet retransmission, and a base station target from a cooperative set of base stations based on the required channel quality. A selection device for selecting a subset; and a transmission device for transmitting an indication of a target subset of a base station to a central device.

  According to a fourth aspect of the present invention, an embodiment of the present invention provides a central device. The central unit receives a packet reception failure and, based on the estimated channel quality required for the next packet retransmission, selects the base station for the next retransmission selected from the coordinated set of base stations. A receiving device that receives an instruction of the target subset, and a notification device that notifies a base station in the target subset to retransmit the packet to the user equipment.

  According to the present invention, the following effects are achieved. That is, when not all eNBs in the cooperative set are required for packet retransmission, some eNBs are spared from transmitting other data information, and thus the throughput performance of the CoMP system is improved.

  Other features and advantages of embodiments of the present invention will become apparent from the following description of specific embodiments, with reference to the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the invention. Let's go.

  The embodiments of the present invention are presented by way of example, and the advantages thereof will be described in more detail below with reference to the accompanying drawings.

3 shows a flowchart of a downlink HARQ function enhancement method according to an embodiment of the present invention. 6 shows a flowchart of a downlink HARQ function enhancement method according to another embodiment of the present invention. FIG. 2 shows a block diagram of a downlink HARQ function enhancement apparatus according to an embodiment of the present invention. 3 shows a flowchart of a downlink HARQ function enhancement method according to an embodiment of the present invention. FIG. 2 shows a block diagram of a downlink HARQ function enhancement apparatus according to an embodiment of the present invention. 1 illustrates an LTE / LTE-A communication system for enhancing downlink HARQ functionality according to an embodiment of the present invention; FIG. 6 shows SINR to capacity mapping according to one embodiment of the present invention. FIG. FIG. 6 shows SINR to BLER mapping in different retransmission attempts according to an embodiment of the present invention. FIG.

  In the following, various embodiments of the present invention will be described in detail with reference to the drawings. The flowchart and block diagrams in the Figures illustrate apparatus, methods, architecture, functions, and operations executable by a computer program product according to an embodiment of the present invention. Each block in the flowchart or block diagram represents a portion of a module, program, or code that includes one or more executable instructions for performing a particular logical operation. It should be noted that in some alternative embodiments, the functions shown in the blocks are performed in a different order than the order shown in the figures. For example, two consecutive blocks may actually be executed substantially in parallel or in reverse order in relation to the related function. It is also noted that the block diagrams, flowchart blocks, and combinations thereof may be implemented by a dedicated hardware-based system for performing a specific function / operation or by a combination of dedicated hardware and computer instructions. I want.

  In the present invention, assuming that the packet has been retransmitted Q times so far, “next retransmission” means the (Q + 1) th retransmission, and “previous retransmission” means a part of the first to Qth retransmissions. Note that it means or all. However, in one embodiment of the present invention, “previous retransmission” means all retransmissions from the first to the Qth.

  The present invention mainly deals with CoMP, and particularly targets CoMP for downlink multi-cell joint transmission.

  The embodiments of the present invention propose a novel scheme for enhancing downlink HARQ capability. The proposed HARQ function enhancement method includes a function enhancement on the UE (User Equipment) side and a function enhancement on the central device side. The CoMP UE first decodes the packet and, if that fails, estimates the required channel quality to recover the data information. Subsequently, based on knowledge of channel quality of eNBs belonging to the cooperative set, it is determined which eNB (or combination of eNBs) in the cooperative set can be used for packet retransmission. Thereafter, the CoMP UE transmits an instruction indicating the eNB used for packet retransmission to the central apparatus. Based on this indication, the central unit releases eNBs that do not need to be used in the cooperative set.

  One embodiment of the present invention discloses a downlink HARQ enhancement method. In response to a packet reception failure, the method estimates a channel quality required for the next packet retransmission and selects a target subset of base stations from a cooperating set of base stations based on the required channel quality And transmitting an indication of the target subset of base stations to the central unit. This method is performed by a UE in an LTE / LTE-A communication system.

  One embodiment of the present invention discloses a downlink HARQ enhancement method. The method comprises receiving an indication of a target subset of a base station for the next retransmission, and notifying a base station in the target subset to retransmit the packet. This method is performed by a central unit in the LTE / LTE-A communication system.

  FIG. 1 shows a flowchart of a downlink HARQ function enhancement method according to an embodiment of the present invention.

  The present embodiment can be implemented in the HARQ process on the UE side as follows. First, data from the eNB is demodulated in the UE. Subsequently, demodulated data with different RVs of the same packet for channel decoding are combined using a tracking combining (CC) scheme or an incremental redundancy (IR) scheme. Thereafter, the combined data is decoded. The CRC value of the decoded packet is calculated and compared with the CRC information carried in the original packet to determine whether the packet has been successfully received. If the reception of the packet is successful, ACK is transmitted, and if it is unsuccessful, NACK is transmitted together with an indication of the target subset of the base station that performs the next retransmission. According to one embodiment of the invention, this indication may be sent simultaneously with the NACK, or a little before or after. This instruction can be acquired by steps S101 to S103.

  In step S101, in response to a packet reception failure, the channel quality necessary for the next packet retransmission is estimated.

In one embodiment of the present application, the channel quality of the previous retransmission is first obtained from each of the coordinated sets of base stations, and then the next retransmission is based on the acquired channel quality and the target channel quality. The required channel quality is determined. Next, step 201 and step 202 of the present embodiment shown in FIG. 2 will be described in detail.

  In step S102, a target subset of base stations is selected from a coordinated set of base stations based on the required channel quality.

  In one embodiment of the present application, a mapping relationship between a subset of base stations in a cooperative set and a predetermined channel quality level is obtained, the required channel quality is compared with a predetermined channel quality level, and the comparison result and the mapping relationship Based on the above, the base station subset corresponding to the required channel quality is determined as the target subset. Next, steps 203 to 205 of this embodiment shown in FIG. 2 will be described in detail.

  In step S103, an indication of the target subset of the base station is transmitted to the central device.

  In one embodiment of the present application, an instruction to indicate a base station in the target subset is determined based on a predetermined correspondence between the instruction and the base station subset in the coordinated set, and the determined instruction Is transmitted to the central unit.

  The flow of the embodiment of FIG.

  It should be noted that many suitable means known in the art can be employed as will be apparent to those skilled in the art, and the methods described herein are provided by way of example and not limitation.

  FIG. 2 shows a flowchart of a downlink HARQ enhancement method according to another embodiment of the present invention.

  In step S201, the previous retransmission channel quality is obtained from each of the coordinated sets of base stations.

  In the present invention, one or more of channel quality is selected from SINR (signal to interference noise ratio), SNR (signal to noise ratio), CINR (carrier to interference noise ratio), and CNR (carrier to noise ratio). The In the present embodiment, as an example, channel quality is expressed using SINR. In other embodiments of the invention, channel quality is expressed as SNR, CINR, CNR, or any combination of SINR, SNR, CINR, and CNR.

In one embodiment of the present invention, it is assumed that there are three base stations (e.g., eNB0, eNB1 and eNB2) that operate as the serving base station of the UE in the cooperative set, and the packet has already been transmitted twice to the UE . The channel quality of the previous retransmission obtained from each of the coordinated sets of base stations is denoted as SINR _{n, i} , where n represents the subcarrier for transmitting packets from the nth eNB to the UE, i Represents the i-th retransmission. The channel quality is obtained from the storage device in which SINR _{n, i} (where n = 0, 1 and 2, i = 1 and 2) obtained from the i th retransmission on the n th subcarrier is stored. Is done.

  As will be appreciated by those skilled in the art, this storage device is a portable computer magnetic disk, hard disk, random access memory (RAM), read only memory (ROM), erasable programmable ROM (EPROM or flash), optical fiber, It may be a portable compact disc ROM (CD-ROM), an optical storage device, or a magnetic storage device.

  As will be appreciated by those skilled in the art, the channel quality SINRn, i is illustratively obtained from storage, but can be obtained by other suitable means known in the art.

  In step S202, the channel quality required for the next retransmission is determined based on the acquired channel quality and target channel quality.

  In the embodiment of the present application, assuming that the packet has been retransmitted Q times so far, “next retransmission” means the (Q + 1) th retransmission, and “previous retransmission” is from the first to the Qth. Note that this means resending of.

  In an embodiment of the present application, data received from a base station (eg, eNB) is demodulated and then combined using a tracking combining (CC) scheme, an incremental redundancy (IR) scheme, etc., and further decoded Is done.

ここで、
Ｉ_ｍ（）は相互情報関数であり、
Ｎは副搬送波数であり、
ＳＩＮＲ_{ｔａｒｇｅｔ，Ｑ＋１}は（Ｑ＋１）番目の再送の目標チャネル品質である。 In one embodiment of the present application, data is combined using a CC scheme. Regarding the SINR of the retransmission packet, all retransmissions are added up. In order to correctly decode the packet, the channel quality obtained after the (Q + 1) th retransmission must exceed the target channel quality of the (Q + 1) th retransmission. If subcarrier n is given, the channel quality required for the (Q + 1) -th retransmission on subcarrier n is expressed as “SINR _{n, Q + 1} ” and is obtained by the following equation set (1).

here,
I _m () is a mutual information function,
N is the number of subcarriers,
SINR _{target, Q + 1} is the target channel quality of the (Q + 1) -th retransmission.

“Target channel quality” is a channel quality threshold value for the next retransmission. The mutual information acquired based on the candidate channel quality SINR _{n, Q + 1} for the next retransmission and the channel quality SINR _{n, i} (i = 1,..., Q) for the previous retransmission is acquired based on the target channel quality. If the mutual information is exceeded, the channel quality SINRn, Q + 1 is used in the next retransmission in order to ensure that the next retransmission packet is successfully received.

  The target channel quality may be preset based on a priori knowledge, obtained by offline link level simulation, or obtained by other suitable means known in the art.

ここで、
Ｎ_ｐｒｅはこの再送で再送されなかったコードビット数であり、
Ｎ_Ｒはこの再送で再送されたコードビット数であり、
Ｎ_ＮＲはこの送信で送信された新たなコードビット数である。 In other embodiments of the present application, data is combined using an IR scheme. In this case, assuming that subcarrier n is given, the channel quality necessary for the (Q + 1) -th retransmission on subcarrier n is expressed as “SINR _{n, Q + 1} ”, and is obtained by the following equation set (2). It is done.

here,
N _pre is the number of code bits not retransmitted in this retransmission,
N _R is the number of code bits retransmitted in this retransmission,
N _NR is the number of new code bits transmitted in this transmission.

  Equation set (2) above shows that the subsequent SINR must exceed the SINR target for the (Q + 1) th retransmission. For incremental redundancy (IR) combining, the combined SINR mutual information on each subcarrier is retransmitted in the (Q + 1) th retransmission to the mutual information of the bits transmitted before the (Q + 1) th retransmission. And the bit newly retransmitted in the (Q + 1) -th retransmission is added. Thus, the SINR required for the (Q + 1) -th retransmission is estimated, and the UE can select an appropriate eNB that meets the SINR requirement.

In another embodiment of the present application, the mutual information after the Qth retransmission is I _m (SINR _{n, Q} ), and the next retransmission packet has the same packet length as the previous retransmission packet to avoid complication. Assuming equation set (2) can be described as inequality (3) below.

In another embodiment of the present application, it is assumed that the SINR requirement in the (Q + 1) th retransmission is the same among all subcarriers. In this case, equation set (2) can be described as equation set (4) below.

Here, mutual information is represented by capacity, and a mapping function between SINR and capacity is as shown in FIG. Also, the mapping between SINR and BLER in different retransmission attempts when modulation / coding scheme MCS = 15 is shown in FIG. Thus, SINR _{target, Q + 1} in the (Q + 1) -th retransmission can be easily calculated assuming that the BLER (block error rate) is 0.1.

  In step S203, a mapping relationship between the base station subset in the cooperative set and a predetermined channel quality level is obtained.

  In one embodiment of the present invention, the mapping relationship between the base station subset and the predetermined channel quality level can be pre-set based on a priori knowledge or can be pre-defined according to criteria of those skilled in the art. Alternatively, it may be determined in advance according to operator specifications.

  In one embodiment of the invention, the mapping relationship between the base station subset and the predetermined channel quality level is stored in advance in a storage device. This storage device includes a portable computer magnetic disk, hard disk, random access memory (RAM), read only memory (ROM), erasable programmable ROM (EPROM or flash), optical fiber, portable compact disk ROM (CD-ROM), It can be an optical storage device, a magnetic storage device, or any other suitable storage device.

In one embodiment of the present invention, a coordinated set of base stations that are UE serving base stations consists of three eNBs, eNB0, eNB1 and eNB2, of which eNB0 is a serving eNB and eNB1 and eNB2 are coordinated eNBs. It is. Table 1 shows an example of the mapping relationship between the base station subsets in the cooperation set and the SINR level.

  As can be seen from Table 1, if the required channel quality is in the range of 0.46 dB to 2.28 dB (including 2.28 dB), or if the required channel quality is less than 0.46 dB, the target subset is 1 Since it is composed of only one base station, that is, eNB0, only eNB0 is suitable for the next retransmission. When the required channel quality is in the range of 2.28 dB to 5.46 dB (including 5.46 dB), the target subset is composed of two base stations, eNB0 and eNB1, and therefore eNB0 and eNB1 in the next retransmission Need to cooperate. When the required channel quality is 5.46 dB to 8.56 dB (including 8.56 dB), the target subset is composed of two base stations, eNB0 and eNB2, so that eNB0 and eNB2 cooperate in the next retransmission. There is a need to. And when the required channel quality exceeds 8.56 dB, the target subset is composed of three base stations, eNB0, eNB1 and eNB2, and therefore eNB0, eNB1 and eNB2 all need to cooperate in the next retransmission. There is.

  In step S204, the required channel quality is compared with a predetermined channel quality level.

When the channel quality SINR _{n, Q + 1} necessary for the (Q + 1) -th retransmission is obtained in step S204, it is compared with a predetermined channel quality level. In one embodiment of the present invention, if the required channel quality SINR _{n, Q + 1} is 2.8 dB, it can be determined that SINR _{n, Q + 1} is in the range of 2.28 dB to 5.46 dB.

  In step S205, based on the comparison result and the mapping relationship, the base station subset corresponding to the required channel quality is determined as the target subset.

As indicated above, if SINR _{n, Q + 1} is in the range of 2.28 dB to 5.46 dB, based on Table 1, the target subset of the base station corresponding to the required channel quality SINR _{n, Q + 1} is eNB 0 And eNB1.

  In step S206, an instruction to indicate base stations in the target subset is determined based on a predetermined correspondence between the instruction and the base station subset in the cooperative set.

  There are several ways to determine the instructions.

Table 2 shows an example of a predetermined correspondence between an instruction and a base station subset in the cooperation set in one embodiment of the present invention.

In downlink CoMP operation, the channel state information (CSI) of the CoMP UE is required for the central device to perform the CoMP scheduling process. Common CSI includes precoding matrix index (PMI), rank indication (RI), channel quality index (CQI), and the like. The UE reports individual cell-specific feedback and complementary feedback that includes a subset of eNBs in the cooperation set. Table 2 shows typical SINR measurement results. From this result, the mapping between SINR and CQI can be obtained. Subsequently, CQI is acquired as CSI information based on the mapping between SINR and CQI. This is later reported with periodic feedback on PUCCH or with periodic feedback on PUSCH.

For example, if the required channel quality SINR _{n, Q + 1} acquired in step S204 is 2.8 dB, it is determined that SINR _{n, Q + 1} is in the range of 2.28 dB to 5.46 dB (step S204). The target subset of the base station corresponding to the quality SINR _{n, Q + 1} is configured by eNB0 and eNB1 (step S205). In step S206, based on Table 2, it is determined that the target subset configured by eNB0 and eNB1 corresponds to the CQI having a value of “7”. In this case, this CQI “7” is an instruction indicating a target subset composed of eNB0 and eNB1.

Table 3 shows an example of a predetermined correspondence relationship between the instruction and the base station subset in the cooperation set in another embodiment of the present invention.

For example, when the target subset of the base station corresponding to the required channel quality SINR _{n, Q + 1} is configured by eNB0 and eNB1, the target subset configured by eNB0 and eNB1 is based on the value “ It can be determined to correspond to a 2-bit message having “01”. In this case, this message “01” is an instruction indicating the target subset configured by eNB0 and eNB1.

  Although only two examples of instructions are shown in the above embodiments of the present invention, those skilled in the art will appreciate that the instructions can be applied in many other suitable forms known in the art. .

  In step S207, the determined instruction is transmitted to the central apparatus.

  According to the present invention, if the packet reception fails, a NACK is transmitted. According to one embodiment of the present invention, the determined indication may be transmitted simultaneously with the NACK, or a little before or after.

  The flow of the embodiment of FIG.

  It should be noted that many other suitable means known in the art can be employed, as will be apparent to those skilled in the art, and the methods described herein are provided by way of example and not limitation.

  FIG. 3 shows a block diagram of a downlink HARQ function enhancement apparatus 300 according to an embodiment of the present invention.

  In one embodiment of the present invention, the device 300 comprises an estimation device 310, a selection device 320 and a transmission device 330. The estimation device 310 is configured to estimate the channel quality required for the next packet retransmission in response to a packet reception failure. The selection device 320 is configured to select a target subset of base stations from a coordinated set of base stations based on the required channel quality. The transmitter 330 is configured to transmit an indication of the target subset of base stations to the central device.

  In one embodiment of the present invention, the estimation means 310 comprises means configured to obtain the channel quality of previous retransmissions from each of the coordinated sets of base stations, and the obtained channel quality and target channel quality. And means configured to determine a channel quality required for the next retransmission based on.

  In one embodiment of the invention, the selection means 320 comprises means configured to obtain a mapping relationship between a base station subset in the cooperating set and a predetermined channel quality level; Means configured to compare with the channel quality level and means configured to determine a base station subset corresponding to the required channel quality as a target subset based on the comparison result and the mapping relationship.

  In one embodiment of the invention, the transmitting means 330 determines an indication to indicate the base stations in the target subset based on a predetermined correspondence between the indicator and the base station subset in the cooperative set. Means configured to: and means configured to transmit the determined indication to the central unit.

  In one embodiment of the invention, at least one of SINR, SNR, CINR and CNR is selected as the channel quality.

  FIG. 4 shows a flowchart of a downlink HARQ function enhancement method according to an embodiment of the present invention.

  In step S401, an indication of the target subset of the base station for the next retransmission is received.

  In one embodiment of the present invention, when an indication of the target subset of the base station for the next retransmission is received, based on a predetermined correspondence between the indicator and the base station subset in the cooperation set, A target subset of base stations is determined.

  There are several ways to determine the base stations in the target subset based on the received indication. As described above, the predetermined correspondences between the instructions and the base station subsets in the cooperative set are illustrated in Tables 2 and 3. Since the correspondence relationship between the target subset and the received instruction can be easily obtained based on the predetermined correspondence relationship in Table 2 or Table 3, the base stations constituting the target subset are determined thereby.

  In step S402, the base station in the target subset is notified to retransmit the packet.

  In this step, only base stations in the target subset receive notification of retransmission execution. Since the base stations in the target subset are only a part of all the base stations in the cooperative set, the radio resources of base stations that do not receive notifications are saved.

  The flow of the embodiment of FIG. 4 ends here.

  It should be noted that many other suitable means known in the art can be employed, as will be apparent to those skilled in the art, and the methods described herein are provided by way of example and not limitation.

  FIG. 5 shows a block diagram of a downlink HARQ function enhancing apparatus 500 according to an embodiment of the present invention.

  In one embodiment of the present invention, the device 500 comprises a receiving device 510 and a notification device 520. The receiving device is configured to receive an indication of a target subset of base stations for the next retransmission. The notification device is configured to notify a base station in the target subset to perform packet retransmission.

  In one embodiment of the present invention, the receiving device 510 is configured to determine a target subset of base stations based on a predetermined correspondence between the indicator and the base station subsets in the cooperating set. Is provided.

  FIG. 6 shows an LTE / LTE-A communication system for enhancing downlink HARQ capability according to an embodiment of the present invention.

  The system includes a central apparatus 610, three base stations (eNB0 620, eNB1 621, and eNB2 622) and a UE 630. The UE 630 includes a HARQ combiner 631, a channel decoder 632, a CRC detector 633, and a downlink HARQ enhancement device 300 according to the present invention shown in FIG. The central device 610 includes a downlink HARQ function enhancement device 500 according to the present invention shown in FIG.

In the system, data transmitted from eNB0 620, eNB1 621, and eNB2 622 is first demodulated by UE 630. Subsequently, demodulated data having different RVs of the same packet for channel decoding are combined in a HARQ combiner 631 using a tracking combining (CC) scheme or an incremental redundancy (IR) scheme. The combined data is decoded by channel decoder 632. Thereafter, the CRC detector 633 calculates the CRC value of the decoded packet and compares it with the CRC information carried in the original packet to determine whether the packet has been successfully received. If the reception of the packet is successful, ACK is transmitted, and if it is unsuccessful, NACK is transmitted together with an indication of the target subset of the base station. This instruction is acquired by the downlink HARQ function enhancement device 300. Specifically, in response to a packet reception failure, the channel quality required for the next packet retransmission is first estimated, and the target subset of the base station is selected from the coordinated set of base stations based on the required channel quality. Finally, an indication of the target subset of base stations is sent to the central unit.

  The central device 610 includes a downlink HARQ function enhancement device 500. In the HARQ process, apparatus 500 receives an indication of the target subset of the base station for the next retransmission and notifies the base stations in the target subset to retransmit the packet.

  With the proposed HARQ function enhancement method and apparatus, the central apparatus can release unnecessary eNBs in HARQ retransmission and cause these eNBs to transmit new information. Therefore, a part of radio resources is saved.

  Each embodiment of the present invention may also be implemented as a computer program product comprising at least one computer readable storage medium storing one computer readable program code portion. In these embodiments, the computer readable program code portion comprises at least code for downlink HARQ function enhancement. In one embodiment of the present invention, the computer program receives a packet reception failure and based on the required channel quality and a code for estimating the channel quality required for the next packet retransmission. A code for selecting a target subset of the base station from the coordinated set of stations and a code for transmitting an indication of the target subset of the base station to the central unit. In one embodiment of the invention, the computer program is for receiving a code for receiving an indication of the target subset of the base station for the next retransmission and for notifying the base stations in the target subset to retransmit the packet. Code.

  Based on the foregoing description, it will be appreciated by one of ordinary skill in the art that the present invention may be implemented within an apparatus, method or computer program product. Thus, the present invention specifically includes complete hardware, complete software (including firmware, resident software, microcode, etc.) or software sections and hardware commonly referred to as “circuits”, “modules”, “systems”. It can be implemented as a combination with the wear part. Furthermore, the present invention can take the form of a computer program product embodied as a tangible expression medium. This medium includes program code usable by a computer.

  Any combination of one or more computer-usable media or computer-readable media can be used. The computer usable medium or computer readable medium is, for example, an electric / magnetic / optical / electromagnetic / infrared / semiconductor system, means, apparatus, or propagation medium. More specific examples (not exhaustive) of computer readable media include electrical connections with one or more leads, portable computer magnetic disks, hard disks, random access memory (RAM), read only memory (ROM) ), Erasable programmable ROM (EPROM or flash), optical fiber, portable compact disc ROM (CD-ROM), optical storage device, transmission medium that supports the Internet and Intranet, magnetic storage device, and the like. Further, the computer usable medium or the computer readable medium may be a paper on which the program is printed or other medium suitable for printing. It can electronically scan these papers and media, then compile, interpret or process them in the appropriate way, and store them in computer memory as needed to obtain the program electronically. That's why. In the context of this document, a computer-usable or computer-readable medium includes, stores, and communicates with a program usable in an instruction execution system, apparatus, and device, or a program associated with the instruction execution system, apparatus, and device. And can be regarded as a medium to propagate or transmit. The computer-usable medium may also comprise data signals that are retained in baseband or propagated as part of a carrier wave to embody computer-usable program code. The computer usable program can be transmitted by an appropriate medium such as wireless, wired, cable, and RF.

  Computer program codes for executing the operations of the present invention include object-oriented program design languages such as Java, Smalltalk, and C ++, conventional procedural program design languages such as “C” program design language, and other similar program designs. One or more program design languages including languages may be combined and described. The program code may be executed in whole or in part on the user computer, or as part of an independent software package, executed on the user computer and partially on a remote computer, or All can be done on a remote computer or server. In the latter case, the remote computer can connect to the user computer via various networks such as a local area network (LAN) or a wide area network (WAN), or an external computer (eg, an Internet service provider can connect via the Internet). It is also possible to connect to a computer provided.

  Furthermore, each block in the flowcharts and block diagrams of the present invention, and combinations of these blocks can be implemented by computer program instructions. Also, these computer program instructions are supplied to a general purpose computer, special purpose computer or other programmable data processing device processor, whereby these instructions executed by the computer or other programmable data processing device are flowcharts or block diagrams. One machine may be formed that is configured to generate means for implementing the functions / calculations described in these blocks.

  Further, these computer program instructions are stored in a computer readable medium capable of instructing a computer or other programmable data processing device to operate in a particular manner, and the instructions stored in the computer readable medium can be used to generate flowcharts, A product can also be formed comprising instruction means for implementing the functions / operations described in the block diagram.

  Still further, the computer program instructions are loaded into a computer or other programmable data processing device, and a series of operational steps are implemented on the computer or other programmable data processing device, and the instructions are transmitted to the computer or other programmable data processing device. It is also possible to form a single computer-implemented process that is configured to provide a process that implements the functions / operations described in the blocks of the flowcharts and / or block diagrams by executing on the device.

  Although exemplary embodiments of the present invention have been described herein with reference to the drawings, the present invention is not limited to these exact embodiments and various modifications can be made by those skilled in the art without departing from the scope and principles of the invention. It will be appreciated that minor changes are possible. All these variations and modifications are intended to be included within the scope of the present invention as defined in the appended claims.

  Further, a part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
A downlink HARQ function enhancement method,
In response to a packet reception failure, estimating the channel quality required for the next packet retransmission;
Selecting a target subset of base stations from a cooperating set of base stations based on the required channel quality;
Transmitting the indication of the target subset of the base station to the central unit.

(Appendix 2)
In response to the packet reception failure, estimating the channel quality required for the next packet retransmission comprises:
Obtaining channel quality of previous retransmissions from each of the coordinated sets of base stations;
The downlink HARQ function enhancement method according to supplementary note 1, comprising: determining a channel quality necessary for the next retransmission based on the acquired channel quality and the target channel quality.

(Appendix 3)
Based on the required channel quality, selecting a target subset of base stations from a coordinated set of base stations comprises:
Obtaining a mapping relationship between a base station subset in the cooperating set and a predetermined channel quality level;
Comparing the required channel quality with a predetermined channel quality level;
The downlink HARQ function enhancement method according to supplementary note 1, comprising: determining a base station subset corresponding to a required channel quality as a target subset based on the comparison result and the mapping relationship.

(Appendix 4)
Sending an indication of the target subset of base stations to the central unit comprises
Determining an indication to indicate a base station in the target subset based on a predetermined correspondence between the indicator and the base station subset in the coordinated set;
The method of claim 1, further comprising: transmitting the determined instruction to the central device.

(Appendix 5)
The downlink HARQ function enhancement method according to supplementary note 1, wherein the channel quality is selected from at least one of SINR, SNR, CINR, and CNR.

(Appendix 6)
A downlink HARQ function enhancement method,
Receiving an indication of a target subset of base stations for the next retransmission;
A method for enhancing a downlink HARQ function, comprising: notifying a base station in a target subset to retransmit a packet.

(Appendix 7)
Receiving an indication of a target subset of base stations for the next retransmission;
The downlink HARQ function enhancement method according to supplementary note 6, comprising a step of determining a target subset of the base station based on a predetermined correspondence relationship between the indicator and the base station subset in the cooperative set.

(Appendix 8)
A downlink HARQ function enhancement device,
An estimation device configured to estimate the channel quality required for the next packet retransmission in response to a packet reception failure;
A selection device configured to select a target subset of base stations from a cooperating set of base stations based on a required channel quality;
A downlink HARQ function enhancement device comprising: a transmission device configured to transmit an indication of a target subset of a base station to a central device.

(Appendix 9)
The estimation device includes:
Means configured to obtain the channel quality of previous retransmissions from each of the coordinated sets of base stations;
The downlink HARQ function enhancing device according to appendix 8, further comprising means configured to determine a channel quality necessary for the next retransmission based on the acquired channel quality and the target channel quality.

(Appendix 10)
The selection device is:
Means configured to obtain a mapping relationship between a base station subset in the cooperating set and a predetermined channel quality level;
Means configured to compare the required channel quality with a predetermined channel quality level;
The downlink HARQ function enhancing apparatus according to appendix 8, further comprising: means configured to determine a base station subset corresponding to a required channel quality as a target subset based on the comparison result and the mapping relationship. .

(Appendix 11)
The transmitter is
Means configured to determine an indication to indicate a base station in the target subset based on a predetermined correspondence between the indicator and the base station subset in the cooperating set;
9. The downlink HARQ enhancement device according to appendix 8, comprising means configured to transmit the determined indication to the central device.

(Appendix 12)
[9] The downlink HARQ function enhancement device according to appendix 8, wherein the channel quality is selected from at least one of SINR, SNR, CINR, and CNR.

(Appendix 13)
A downlink HARQ function enhancement device,
A receiver configured to receive an indication of a target subset of base stations for a next retransmission;
A downlink HARQ function enhancing apparatus comprising: a notification apparatus configured to notify a base station in a target subset to retransmit a packet.

(Appendix 14)
The receiving device is:
The downlink HARQ function according to appendix 13, comprising means configured to determine a target subset of the base stations based on a predetermined correspondence between the indicator and the base station subsets in the cooperative set Strengthening device.

300: Device 310: Estimation device 320: Selection device 330: Transmission device 500: Device 510: Reception device 520: Notification device 610: Central device 620: eNB0
621: eNB1
622: eNB2
630: UE
631: HARQ combiner 632: Channel decoder 633: CRC detector

Claims (10)

A method performed by a user equipment in a communication system, comprising:
In response to a packet reception failure, estimate the channel quality required for the next packet retransmission,
Based on the desired channel quality, select a target subset of base stations from a coordinated set of base stations,
Send an indication of the target subset of base stations to the central unit;
A method characterized by that. Upon estimating the channel quality required for the next packet retransmission in response to the packet reception failure,
Obtaining the channel quality of the previous retransmission from each of the coordinated sets of base stations,
Based on the acquired channel quality and target channel quality, determine the channel quality required for the next retransmission,
The method according to claim 1. When selecting a target subset of base stations from a coordinated set of base stations based on the required channel quality,
Obtaining a mapping relationship between a base station subset in the cooperating set and a predetermined channel quality level;
Compare the required channel quality with a given channel quality level,
Based on the comparison result and the mapping relationship, a base station subset corresponding to the required channel quality is determined as a target subset.
The method according to claim 1. When sending the indication of the target subset of the base station to the central unit,
Determining an indication to indicate a base station in the target subset based on a predetermined correspondence between the indicator and the base station subset in the cooperative set;
Sending the determined instructions to the central unit;
The method according to claim 1.   The method of claim 1, wherein the channel quality is selected from at least one of SINR, SNR, CINR, and CNR. An estimation device that estimates the channel quality required for the next packet retransmission in response to a packet reception failure;
A selection device for selecting a target subset of base stations from a coordinated set of base stations based on a required channel quality;
A transmitting device that transmits an indication of a target subset of base stations to a central device;
User equipment characterized by comprising: The estimation device includes:
Means for obtaining channel quality of previous retransmissions from each of the coordinated sets of base stations;
Means for determining the channel quality required for the next retransmission based on the acquired channel quality and the target channel quality;
The user equipment according to claim 6 , further comprising: The selection device is:
Means for obtaining a mapping relationship between a base station subset in the cooperating set and a predetermined channel quality level;
Means for comparing the required channel quality with a predetermined channel quality level;
Means for determining, as a target subset, a base station subset corresponding to a required channel quality based on the comparison result and the mapping relationship;
The user equipment according to claim 6 , further comprising: The transmitter is
Means for determining an indication to indicate a base station in the target subset based on a predetermined correspondence between the indicator and the base station subset in the cooperative set;
Means for transmitting the determined instructions to the central unit;
The user equipment according to claim 6 , further comprising: The user equipment of claim 6 , wherein the channel quality is selected from at least one of SINR, SNR, CINR and CNR.

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