CN108540985B

CN108540985B - Method for sharing PDSCH and PDCCH resources in NR system

Info

Publication number: CN108540985B
Application number: CN201810167270.XA
Authority: CN
Inventors: 李勇; 刘春花
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2018-02-28
Filing date: 2018-02-28
Publication date: 2021-02-05
Anticipated expiration: 2038-02-28
Also published as: CN108540985A

Abstract

The invention discloses a method for sharing resources of a PDSCH and a PDCCH in an NR system, belonging to the technical field of mobile communication. The method comprises the following steps: step one, the gNB corresponds the UE ID and index in RRC CONNECTED one by one to form a mapping table and informs all the UE; step two, the gNB dynamically informs the current scheduling condition of each UE through signaling in a bit mapping mode; and thirdly, the UE obtains the index of the currently scheduled UE according to the signaling in the second step, and deduces the UE ID currently scheduled by the gNB according to the mapping table obtained in the first step. Calculating a search space with DCI by combining the slot number and the sequence number of CORESET; and fourthly, avoiding the time-frequency resources corresponding to the search spaces when the UE maps the resources, and realizing the resource sharing of the PDCCH and the PDSCH. The invention not only can realize the compromise between the resource utilization rate and the signaling complexity, but also can be widely applied to indicating the internal idle resources of CORESET with various sizes.

Description

Method for sharing PDSCH and PDCCH resources in NR system

Technical Field

The invention belongs to the technical field of mobile communication, and particularly relates to a method for sharing resources of a PDSCH (physical Downlink shared channel) and a PDCCH (physical Downlink control channel) in an NR (noise reduction) system.

Background

The channel bandwidth of a Long Term Evolution (LTE) system is up to 20MHz, and the control domain occupies the first 1-4 orthogonal frequency division multiple access (OFDM) symbols of a subframe in the time domain and the entire system bandwidth in the frequency domain. However, the Channel bandwidth in the NR (new air interface) system is as high as 400MHz, on one hand, considering that the bandwidth capability of some User Equipments (UEs) is limited, and on the other hand, in order to avoid that the UE detects a PDCCH (Physical Downlink Control Channel) on the whole Channel bandwidth, which refers to a Physical Downlink Control Channel, which causes a large power overhead, the NR introduces the concept of a Control resource set (CORESET). The CORESET is a time-frequency resource block configured for transmitting Downlink Control Information (DCI), and in a time domain, one CORESET can be configured into one or one group of continuous OFDM symbols, and the number of the continuous OFDM symbols is not more than three; in the frequency domain, CORESET is composed of a set of contiguous or non-contiguous Physical Resource Blocks (PRBs). In the NR system, at least one UE-specific core may be configured in addition to a common core obtained from a master information block/system information (MIB/SI), and the core may be configured using dedicated Radio Resource Control (RRC) signaling. In addition, the NR base station (gNB) may inform the UE which control channel candidates are mapped to each OFDM symbol subset in the CORESET.

Fig. 1 shows the configuration of three different CORESET, where CORESET 1, CORESET 2, and CORESET 3 respectively occupy three, one, and two consecutive OFDM symbols (slots), and in order to fully utilize time-frequency resources, idle resources outside CORESET are used for transmitting PDSCH (physical downlink channel). However, considering that the resources for transmitting the DCI by the CORESET are dynamically changed, only a small number of resources inside some CORESETs actually transmit the DCI or even not transmit the DCI (for example, the CORESET 1 in fig. 1 has a large configured resource but only transmits one DCI, and there is no DCI transmission in the CORESET 2), which results in waste of the resources available inside the CORESET.

Currently, two mainstream schemes for resource sharing are shared, one is resource sharing based on the CORESET size, and the other is resource sharing based on the DCI.

For resource sharing based on the size of the CORESET, in the case that the gNB dynamically or periodically indicates the usage of each CORESET resource, the UE occupies the unused CORESET and performs rate matching around the CORESET transmitted with DCI when all the CORESET resource configuration information is known, which has the advantages of simple implementation and low signaling overhead, and has the disadvantage that once the CORESET configured by the UE is large and the actual DCI transmission resource is small, the available resources inside the CORESET are wasted.

For DCI-based resource sharing, the UE may transmit PDSCH on free resources within the CORESET where DCI is not transmitted. The UE needs to know the resource for actually transmitting the DCI in the CORESET, including the DCI for scheduling data transmission of the UE itself and the DCI for scheduling data transmission of other UEs, which is relatively complex to implement, but the reasonable idle resource indication method can effectively improve the resource utilization rate.

One implementation is based on an indication of control channel element groups (CCE groups). Grouping internal resources of CORESET according to CCE, defining M continuous CCE as a group, indicating the occupation condition of each CCE group resource according to a bit mapping mode, once the resource is occupied, setting the binary position of the corresponding position of the CCE group as '1', otherwise, setting the binary position as '0'. As shown in fig. 2, the core set is divided into six groups, the first group and the fifth group have DCI transmission, so that binary numbers of corresponding bits of the first group and the fifth group are respectively set to '1', and the gNB dynamically indicates the occupation of resources inside the core set by the UE through signaling "100010", thereby avoiding PDSCH transmission in the first group and the fifth group. Although this approach is simple, it has the following problems: (1) the overhead (payload) of dynamic signaling indicating the free resources inside the CORESET is related to the size of the CORESET and the size of the CCE group, and when the CORESET becomes large, the size of the CCE group must be increased without increasing the payload size of the dynamic signaling, but a large CCE group may cause insufficient utilization of the free resources. (2) When Resource Element Groups (REGs) to CCEs are in distributed mapping, resources occupied by a single CCE in the CORESET are sparsely distributed, and the REG-CCE mapping mode needs to be considered when setting CCE groups, rather than the continuous CCE group setting mode shown in fig. 2.

Therefore, how to effectively realize the multiplexing of free resources inside the CORESET becomes a big difficulty, which is the key point of how to indicate the free resources inside the CORESET.

Disclosure of Invention

The invention aims to solve the problem of how to design an idle resource indication method to realize the effective utilization of CORESET internal resources when the PDSCH and PDCCH resources in NR are shared.

In order to solve the above technical problem, the present invention provides a method for sharing PDSCH and PDCCH resources in NR system, which is based on the following two assumptions:

1) in the NR system, configuration information of each CORESET is shared by all UEs;

2) CORESET is large, up to tens of CCEs;

based on the two assumptions, the invention provides a method for sharing PDSCH and PDCCH resources in an NR system, which comprises the following steps: the resource sharing is a search space specific to all aggregation levels of a certain UE, which mainly considers that DCI is a dynamic signaling configuration based on a Media Access Control (MAC) layer, while the configuration of the search space is a semi-static signaling based on RRC (related to radio network temporary identity), the former dynamically changes with time, resulting in complex and variable idle resource indication in the DCI-based resource sharing; the latter is only related to the UE ID and slot number (NR may also be related to the CORESET serial number), the change of the UE ID in a period of time is not significant, because the slot number is known to all UEs that acquire cell synchronization, the gNB only needs to indicate all UE IDs currently scheduled, and all UEs can calculate which search spaces may have DCI, thereby avoiding these resources, and performing rate matching near these resources, so how to indicate the currently scheduled UE ID becomes the key point of the present invention.

The invention discloses a method for sharing PDSCH and PDCCH resources in an NR system, which comprises the following steps:

step one, the gNB configures a table, forms a mapping table by one-to-one correspondence between the UE ID and index in RRC CONNECTED, and notifies all the UEs. The mapping table of the UE ID and the index can adopt two mapping modes according to the load of the cell: each CORESET uses only one mapping table and all CORESETs share one mapping table.

The one-to-one correspondence only between the UE ID and index of RRC CONNECTED is because the UE will receive the DCI specific to the UE, and the DCI received by the UE in RRC IDLE state is common

DCI, common search space containing common DCI, is common to all UEs and therefore does not need to be dynamically notified to the UEs.

And step two, the gNB dynamically informs the current scheduling condition of each UE through signaling in a bit mapping mode.

Since the UE already knows the UE ID corresponds to the index in the first step, the dynamic signaling in the second step sets the binary bit of the corresponding index bit to 0 or 1 according to the current UE ID scheduled, for example, 1 represents scheduled, and 0 represents not scheduled.

When the number of users served by the cell is increased, the gNB does not send signaling, which indicates that the UE cannot share the CORESET internal resources. In addition, if the UE does not receive the signaling, the UE may directly default that there is no PDSCH in the CORESET, and for the case that the gNB transmits DCI and the UE does not receive DCI, it is equivalent to that there is a PDSCH in the CORESET actually, and the UE considers that there is no PDSCH transmitted, which may affect the correct decoding of the PDSCH, and may cause the retransmission of the PDSCH.

And thirdly, the UE obtains the index of the currently scheduled UE according to the signaling in the second step, and deduces the UE ID currently scheduled by the gNB according to the mapping table obtained in the first step. And calculating which search spaces have the DCI by combining the slot number and the sequence number of the CORESET.

And fourthly, according to the search spaces with the DCI calculated in the third step, the UE avoids time frequency resources corresponding to the search spaces during resource mapping and performs rate matching near the time frequency resources, so that resource sharing of the PDCCH and the PDSCH is realized.

The invention not only can realize the compromise between the resource utilization rate and the signaling complexity, but also can be widely applied to indicating the internal idle resources of CORESET with various sizes.

Drawings

Fig. 1 is a schematic diagram of a CORESET configuration in the prior art.

Fig. 2 is a schematic diagram of a method for indicating idle resources inside a CORESET based on CCE group in the prior art.

Fig. 3 is a flowchart of a method for sharing PDSCH and PDCCH resources in the NR system according to the present invention.

Detailed Description

The invention provides a method for sharing resources of a PDSCH and a PDCCH in an NR system, which is used for realizing the resource sharing of the PDCCH and the PDSCH.

Example 1:

a method for sharing PDSCH and PDCCH resources in an NR system comprises the following steps:

1) when the UE is in RRC CONNECTED, the gNB allocates an index for the UE, has a table, corresponds the UE ID and the index one by one, and informs all the UEs through broadcast signaling;

once a certain UE leaves the RRC CONNECTED state, the gNB deactivates or deletes the corresponding index. The gNB may set a periodic update list and notify all UEs. Thus, each UE in RRC CONNECTED state has its own unique index, assuming that the maximum value of the index is K.

2) When sharing of PDCCH and PDSCH is to be achieved, the gNB dynamically informs all UEs with resource sharing capability that all users are currently scheduled through a kind of signaling, such as broadcast signaling, group common PDCCH, or common PDCCH.

Specifically, the signaling is a binary sequence with a length of K, and whether each user is scheduled or not is represented by a binary number located in an index bit (e.g., '1' corresponds to being scheduled and '0' corresponds to not being scheduled). Thus, the UE knows the scheduled UE ID in combination with the signaling of this step and the broadcast signaling of the first step.

3) The UE calculates the search space of the scheduled users according to the UE ID, slot number and CORESET index of the scheduled UE.

4) And the UE avoids the time-frequency resources corresponding to the search spaces when performing resource mapping, and performs rate matching near the time-frequency resources to realize resource sharing of the PDCCH and the PDSCH.

Example 2

1) the gNB configures a table for each CORESET, associates UE IDs and indexes of PDCCHs possibly existing in the CORESET one by one, and notifies all the UEs through broadcast signaling, and the quantity of the UE indexes in each CORESET is assumed not to exceed K.

2) And the gNB dynamically informs the current scheduling condition of each UE of the UE through signaling in a bit mapping mode.

Because the RRC signaling informs the user of the time-frequency position of each core set, when receiving the resources allocated by the gbb for the PDSCH, the UE can estimate which core set the partial PDSCH in the control domain is specifically located in, and thus, the gbb informs the user of the existence of the PDCCHs of all UEs in the core set through the UE specific DCI. Specifically, the signaling is a binary sequence with a length of K, and whether each user is scheduled or not is represented by a binary number located in an index bit, such as '1' corresponding to scheduling and '0' corresponding to non-scheduling.

When the number of core esets occupied by the UE is greater than 1, multiple pieces of DCI may be configured to indicate the PDCCH occupancy inside each core eset, and the DCI may be sequentially placed in a user-specific search space according to an index of the core eset itself for transmission, so that the UE may understand which core eset each piece of DCI specifically corresponds to, which is equivalent to that the UE needs to monitor multiple pieces of DCI at one time.

3) And the UE combines the signaling in the steps 1) and 2) to obtain the UE ID of the scheduled user in the CORESET, and then calculates the search space of the scheduled users.

Claims

1. A method for sharing PDSCH and PDCCH resources in an NR system is characterized in that: the method is based on the following two assumptions:

(1) in the NR system, configuration information of each CORESET is shared by all UEs;

(2) CORESET is large, up to tens of CCEs;

the method specifically comprises the following steps:

step one, the gNB configures a table, and forms a mapping table by one-to-one correspondence between the UE ID and index in RRC CONNECTED and notifies all the UE;

step two, the gNB dynamically informs the current scheduling condition of each UE through signaling or a channel by adopting a bit mapping mode;

thirdly, the UE obtains the index of the currently scheduled UE according to the signaling or the channel in the second step, and deduces the UE ID currently scheduled by the gNB according to the mapping table obtained in the first step; calculating a search space with DCI by combining the slot number and the sequence number of CORESET;

2. The method of claim 1, wherein the method comprises the steps of: the mapping table of the UE ID and the index in the first step adopts two mapping modes according to the load of the cell: each CORESET uses only one mapping table and all CORESETs share one mapping table.

3. The method of claim 1, wherein the method comprises the steps of: the signaling or channel in the second step is broadcast signaling, group common PDCCH or common PDCCH.