CN116326079A

CN116326079A - Search space bundle

Info

Publication number: CN116326079A
Application number: CN202180059107.1A
Authority: CN
Inventors: 王宏志; 欧麦尔·萨利姆; 赛巴斯钦·华格纳
Original assignee: Huizhou TCL Cloud Internet Corp Technology Co Ltd
Current assignee: Huizhou TCL Cloud Internet Corp Technology Co Ltd
Priority date: 2020-07-23
Filing date: 2021-07-20
Publication date: 2023-06-23
Also published as: WO2022017399A1

Abstract

A method for transmitting bonded search spaces for downlink control channels in an OFDM transmission system. Different monitoring opportunities or search spaces of different CORESET may be bundled to achieve repetition of the downlink control channel. This may enable efficient transmission of the downlink control channel without blocking the CORESET.

Description

Search space bundle

Technical Field

The present invention relates to binding of search spaces for PDCCH transmissions, in particular for reduced capability devices.

Background

Wireless communication systems, such as third-generation (3G) mobile phone standards and technologies, are well known. Such 3G standards and techniques have been developed by the third generation partnership project (Third Generation Partnership Project,3 GPP) (RTM). Third generation wireless communications have been developed in general to support macrocell mobile telephone communications. Communication systems and networks have evolved to broadband and mobile systems.

In a cellular wireless communication system, a User Equipment (UE) is connected to a radio access network (Radio Access Network, RAN) by a wireless link. The RAN includes a set of base stations that provide radio links to UEs in a cell covered by the base stations and an interface to a Core Network (CN) that provides overall Network control. It should be appreciated that the RAN and CN each perform a respective function related to the overall network. For convenience, the term cellular network will be used to refer to the combined RAN & CN, and it should be understood that the term is used to refer to the corresponding system for performing the disclosed functions.

The third generation partnership project has developed a so-called long term evolution (Long Term Evolution, LTE) system, i.e. an evolved universal mobile telecommunications system terrestrial radio access network (Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, E-UTRAN) for mobile access networks in which one or more macro cells are supported by base stations called enodebs or enbs (evolved nodebs). Recently, LTE is further evolving towards so-called 5G or NR (new radio) systems, where one or more cells are supported by a base station called a gNB. NR is proposed to use an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexed, OFDM) physical transport format.

The NR protocol is intended to provide the option of operating in the unlicensed radio frequency range (referred to as NR-U). While operating in the unlicensed radio band, the gNB and UE must compete with other devices for physical media/resource access. For example, wi-Fi (RTM), NR-U, and LAA may use the same physical resources.

The trend in wireless communication is to provide lower latency and higher reliability services. For example, NR is intended to support Ultra-reliable and low-latency communication (URLLC), while being large Scale Machine-type communication (mMTC) is intended to provide low latency and high reliability for small packet sizes (typically 32 bytes). The user plane delay of 1ms is proposed, the reliability is 99.99999%, and 10 is proposed in the physical layer ^-5 Or 10 ^-6 Packet loss rate of (a).

The mctc service aims to support a large number of devices over a long life-cycle through an energy efficient communication channel, where data transmission with each device is sporadic and infrequent. For example, one cell may need to support thousands of devices.

The following invention relates to various improvements to cellular wireless communication systems.

Disclosure of Invention

The present invention is defined by the claims, providing a method of transmitting downlink control information in a cellular communication network using an OFDM transmission format, comprising defining a search space bundle for transmitting downlink control channels, wherein the search space bundle comprises a control channel component of at least two monitoring occasions; and transmitting a downlink control channel in the control channel component of the first of the at least two monitoring occasions and transmitting a repetition of at least a portion of the downlink control channel in the control channel component of the second of the at least two monitoring occasions.

The transmissions in the first monitoring occasion use a different aggregation level than the transmissions in the second monitoring occasion.

The repetition repeats systematic bits of the downlink control channel and includes parity bits that are different from the first transmission.

The control channel components of the first and second monitoring occasions are in the same CORESET.

The search space bundle includes at least one set of search spaces set in CORESET for each monitoring occasion.

The method further comprises the step of transmitting an indication of the association between the at least two search spaces.

The indication allows the UE to decode the repetition without blind decoding.

The search space bundle includes a single set of search spaces set at each monitoring occasion.

The control channel components of the first and second monitoring occasions are in different coreses.

The repetition includes a subset of bits transmitted in the first transmission, the method further including transmitting a second repetition of at least a portion of the downlink control channel, wherein the second repetition includes a different subset than the subset transmitted in the first repetition.

The location of the control channel component of the second monitoring occasion is correlated with the location of the control channel component of the first monitoring occasion.

The method further includes transmitting information about the search space bundle.

The information includes an indication of how the location of the control channel component of the second monitoring occasion relates to the location of the control channel component of the first monitoring occasion.

The information includes an identification of CORESET containing the control channel component that is bonded.

The CORESET is identified by a particular CORESET ID.

The particular CORESET ID is defined based on the CORESET ID of the CORESET contained in the search space bundle.

The systematic bits are bits representing the DCI message and the CRC.

The CCE index of the control channel component used by the second monitoring occasion is defined by a function of the CCE index of the control channel component used by the first monitoring occasion.

The function is:

CCE index _Binding =f (CCE index) _{Initial initiation} CORESET size, number of repetitions, aggregation level).

There is also provided a method of transmitting downlink control information in a cellular communication network using an OFDM transmission format, comprising defining a search space bundle for transmitting downlink control channels, wherein the search space bundle comprises at least two control channel components of a CORESET in a single monitoring occasion; and transmitting a downlink control channel in a control channel component of a first one of the at least two corefets, and transmitting a repetition of at least a portion of the downlink control channel in a control channel component of a second one of the at least two corefets.

The transmissions in the first CORESET use a different aggregation level than the transmissions in the second CORESET.

The location of the control channel component of the second CORESET is related to the location of the control channel component of the first CORESET.

The method also includes transmitting information about the search space bundle.

The information includes an indication of how the location of the control channel component of the second CORESET relates to the location of the control channel component of the first CORESET.

The CORESET is identified by a particular CORESET ID.

The systematic bits are bits representing the DCI message and the CRC.

The CCE index of the control channel component used by the second CORESET is defined by a function of the CCE index of the control channel component used by the first CORESET.

The function is:

CCE index _Binding =f (CCE index) _{Initial initiation} CORESET size, weightComplex times, aggregation level).

There is also provided a method performed at a UE in a cellular communication network using an OFDM transmission format, comprising defining a search space bundle for receiving a downlink control channel, wherein the search space bundle comprises a control channel component of at least two monitoring occasions; and receiving a downlink control channel in a control channel component of a first one of the at least two monitoring occasions and receiving a repetition of at least a portion of the downlink control channel in a control channel component of a second one of the at least two monitoring occasions.

The transmission in the first monitoring occasion is received using a different aggregation level than the transmission in the second monitoring occasion.

The indication allows the UE to decode the repetition without blind decoding.

The repetition includes a subset of bits transmitted in the first transmission, and the method further includes receiving a second repetition of at least a portion of the downlink control channel, wherein the second repetition includes a different subset than the subset transmitted in the first repetition.

The method also includes receiving information about the search space bundle.

The CORESET is identified by a particular CORESET ID.

The systematic bits are bits representing the DCI message and the CRC.

The function is:

The UE blindly decodes the first transmission and decodes the second transmission based on the received indication.

There is also provided a method performed at a UE in a cellular communication network using an OFDM transmission format, comprising defining a search space bundle for receiving a downlink control channel, wherein the search space bundle comprises at least two control channel components of a CORESET in a single monitoring occasion; and receiving a downlink control channel in a control channel component of a first one of the at least two CORESETs, and receiving a repetition of at least a portion of the downlink control channel in a control channel component of a second one of the at least two CORESETs.

The transmission in the first CORESET is received using a different aggregation level than the transmission in the second CORESET.

The CORESET is identified by a particular CORESET ID.

The systematic bits are bits representing the DCI message and the CRC.

The function is:

A base station configured to perform the method is also provided.

A UE configured to perform the method is also provided.

Drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings. The components in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the corresponding drawings for ease of understanding.

Fig. 1 illustrates selected components of a cellular communication network;

FIG. 2 shows an example of two binding of CORESET;

FIG. 3 shows an example of binding two CORESET at a time;

fig. 4 shows an example of repetition of forming a PDCCH;

fig. 5 shows an example of soft combining;

fig. 6 shows an example of forming a PDCCH signal; and

Fig. 7 shows another example of soft combining.

Detailed Description

Those skilled in the art will recognize and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

Fig. 1 shows a schematic diagram of three base stations (e.g., enbs or gnbs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each base station will be deployed by one cellular network operator to provide geographic coverage for UEs in that area. The base stations form a radio area network (Radio Area Network, RAN). Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected by an X2 interface and connected to the core network by an S1 interface. It should be understood that only basic details are shown for the purpose of illustrating key features of a cellular network. A PC5 interface is provided between UEs for side-chain (SL) communication. The interface and component names associated with fig. 1 are for example only, and different systems operate on the same principles, possibly using different nomenclature.

Each base station contains hardware and software for implementing RAN functions, including communication with the core network and other base stations, control and data signaling between the core network and the UE, and the UE associated with each base station maintains wireless communication. The core network includes hardware and software that implements network functions such as overall network management and control, and routing of calls and data.

It is proposed to use a reduced capability (Reduced Capability, REDCAP) device in the NR for use cases requiring more functionality than LPWA (LTE-M/NB-IoT) but less URLLC/eMBB services. Cost reduction is a major driving force, but it is also attractive to extend battery life and reduce size. One aspect of the REDCAP device proposal is to reduce the number of antennas and device bandwidth, which may result in reduced coverage for REDCAP devices.

Due to the reduced number of UE RX antennas and bandwidth, it is expected that the downlink coverage will be affected. Simulation results in R1-2003303 show that aggregation level 16 has a performance loss of approximately 3dB when the RX antenna is reduced from 4RX to 2RX, and about 6dB when the RX antenna is reduced from 4RX to 1 RX. Due to this performance degradation, one particular concern is the reliability of the PDCCH, which may not be able to use the highest aggregation level due to the reduced bandwidth of the REDCAP. Disclosed below are methods and techniques that aim to compensate PDCCH coverage reduction for reduced performance devices but are also applicable to devices and systems.

The present invention uses the following terminology. The invention is mainly directed to the NR standard but is also applicable to the LTE standard.

A Resource Block (RB) is the smallest unit of time/frequency resources that can be allocated to a user. The resource block is x-KHz wide in frequency and 1 slot in time. The number of subcarriers used per resource block of PDCCH is 12, and the specific value of x depends on the subcarrier spacing (x=12×scs), which may be 15KHz, 30KHz, 60KHz, etc. In terms of time, the slot duration in the default NR is 14 OFDM symbols, but mini-slot durations (e.g. OFDM symbols of 1, 2, 4, 7, etc.) are also possible. The exact duration of a slot in milliseconds (ms) depends on the number of OFDM symbols on this given slot and SCS, e.g. 1 slot is 1ms long for 15KHz SCS and 14 OFDM symbols.

During one OFDM symbol, one resource-element group (REG) is equal to one RB.

One control-channel element (CCE) consists of 6 REGs.

The physical downlink control channel (physical downlink control channel, PDCCH) is the physical channel carrying downlink control information (downlink control information, DCI). The PDCCH consists of one or more CCEs (e.g., L.epsilon. {1,2,4,8 }). This number is defined as CCE aggregation level (aggregation level, AL). For PDCCH blind decoding, a set of ALs and PDCCH candidates per CCE AL for each DCI format size monitored by the UE may be configured.

For each serving cell, the UE is configured with multiple sets of control resources (control resource set, CORESET) to monitor the PDCCH. Each CORESET is defined as follows: start OFDM symbol, duration (consecutive symbols, up to 3), RB set, CCE to REG mapping (and REG bundling size in case of interlace mapping).

CCEs may be mapped to REGs in CORESET in a localized or distributed manner. The distributed resource mapping is achieved by interleaving, which operates on REG packets. In the case of non-interleaved CCE to REG mapping, b=6. In the case of interleaved CCE-to-REG mapping, B ε {2,6} is for 1 or 2 symbol COESET and B ε {3,6} is for 3 symbol COESET.

The PDCCH search space at CCE AL L is defined by a set of PDCCH candidates for this CCE AL.

We define PDCCH blocking as when the base station (or network) does not have sufficient resources in the control region (or CORESET) of the cell, at least one user in the cell is not allocated these control resources and is not scheduled in the current transmission, although it needs service in the current transmission. The PDCCH blocking probability is the probability that this event occurs.

In order to enhance the coverage of the PDCCH search space, a bonding technique is disclosed below. These techniques aim to provide improved flexibility for PDCCH scheduling compared to using higher aggregation levels, while remaining within practical limitations of decoding PDCCH, particularly considering that the goal of these techniques is devices with reduced capabilities. The purpose of the following disclosure is to achieve similar performance to higher aggregation levels without consuming more resources. In the first technique, the search space bundles may be implemented for different monitoring occasions of the same CORESET, while in the second technique, the search space bundles are used for the same or different monitoring occasions, but with different CORESETs.

In general, PDCCH transmissions with higher aggregation levels consume a lot of resources and congestion is an important issue, as the network may not have enough resources in the control region for other UEs in the same monitoring occasion, which is more serious for the bandwidth-reduced REDCAP device. In a first example, PDCCH repetition is performed in a set of bundled search spaces, which are on different monitoring occasions, but in the same core, as shown in fig. 2. The aggregation level of each search space is less than the aggregation level. This is required if transmitted in only one search space, but due to the time repetition between monitoring opportunities, considerable reliability can be achieved. This technique reduces the resources required for each monitoring occasion due to the lower aggregation level. However, the decoding delay increases.

The binding of the search space for PDCCH repetition may be preconfigured for the relevant UE, e.g. using higher layer (RRC) signaling.

The use of different aggregation levels at each monitoring occasion may also provide increased flexibility by selecting particular combinations, and additional aggregation levels may be implemented. For example, the network may configure one aggregation level 4 transmission and one aggregation level 8 transmission in two consecutive monitoring occasions of CORESET, which is expected to provide equivalent performance to one transmission of aggregation level 12.

Soft combining can be used to benefit from time repetition of PDCCH, but if repetition information is not provided in advance, it increases the complexity of decoding operation and blind decoding, since the UE has to blind decode all possible bindings. The configuration of the shared binding with the UE in advance reduces the complexity of blind decoding.

In the example of fig. 2, one candidate in the first search space is associated with one candidate in the second search space. Search space 1 is configured with candidates for aggregation levels 1 and 2 (AL 1 and 2), and search space 2 is configured with candidates for aggregation levels 2 and 4 (AL 2 and 4). This configuration may be performed using the parameter nrofCandidates in the search space configuration. In fig. 2, the candidate in the first search space has AL2 (CCE index 0), while the candidate in the second search space has AL4 (CCE index 4). The specific candidates and configurations are given only to illustrate the principle of defining a mapping between candidates in different search spaces in order to repeat the PDCCH in time.

The repetition of PDCCH in the same CORESET may be configured using one of the following methods.

First, two different sets of search spaces are configured on one CORESET for PDCCH repetition and their association is indicated to the UE. The association allows the UE to decode the repetition without blind decoding.

A single set of search spaces is configured and the PDCCH is repeated on different instances of the same set of search spaces. The PDCCH configuration indicates to the UE which blind decoding it will perform to jointly decode the PDCCHs from the two instances of the search space.

The PDCCH configuration via the information component PDCCH-config includes information about the search space bundles and is signaled to the UE. The binding information includes:

which set of search spaces are bound (there may be multiple bindings). In the binding, only a single search space set can be indicated, in which case PDCCH repetition is performed between PDCCH candidates of the single search space set.

Information about how the PDCCH is transmitted in the bundling search space (e.g., repetition scheme).

A special search space may be defined, which may be used only for PDCCH repetition. As an example, the search space 1, SS1 may be configured with repeated or non-repeated PDCCHs. It can be bound with SS2 configured for binding purposes only. Therefore, only the PDCCH that has been transmitted through SS1 may be repeated through SS 2. To achieve this flexibility of PDCCH repetition without exponential complexity, SS2 may be configured with a limited number of suitable PDCCH candidates that the configured UE will use to jointly decode the repeated PDCCHs.

In an alternative configuration, search spaces in different CORESET may be bundled for PDCCH repetition, as shown in fig. 3. In a configuration similar to the previous arrangement, a different aggregation level may be used for each repetition in a different CORESET.

The new CORESET ID may be used to indicate the CORESET being used. For example, when two CORESETs are used in one BWP, the temporary CORESET ID may be defined as follows:

new CORESET id= 3*CORESET ID 1+CORESET ID 2

The new CORESET ID is transmitted by the network to the UE using RRC signaling. At the UE, two CORESET IDs may be calculated using a modulo function. The same method can also be used to create a new search space ID. The search space list and the CORESET list are contained in the information component PDCCH-config. So that the new CORESET ID or search space ID can be used as an indication of the CORESET or search space bound in the list.

In the example of fig. 3, the PDCCH is repeated in different CORESETs of the same monitoring occasion. Thus, in this example, the repetition is in the frequency domain. The same principle applies to the use of different CORESETs in different monitoring applications. The search spaces of different CORESET may be bundled repeatedly for PDCCHs of the same DCI content. Thus, since different CORESETs are located on different frequency bands, additional diversity gain may be obtained due to repetition in different CORESETs. The configuration of PDCCH repetition may be set by the two methods explained above.

The PDCCH message to be transmitted in the repetition may be defined as described in the following disclosure. The systematic bits (i.e., the bits representing the message information and the associated CRC bits) are transmitted using a different set of parity bits in each repetition, and some additional redundancy bits are transmitted in each repetition.

The different redundancy versions for each repetition are generated by puncturing the channel coded bits of the systematic bits. Each repetition has a set of code bits that is different from the previous repetition; the systematic bits are transmitted in each repetition, but the parity bits are different for each repetition. At the receiver, each received repetition may be stored in a buffer and combined with subsequent repetitions to improve decoding. The effect of this approach is that the code rate decreases with each repeated reception. Each redundancy version with a high code rate should be part of a low code rate mother code.

Fig. 4 illustrates an example of PDCCH repetition constructed using systematic bits and different sets of parity bits (P1, P2, and P3), as discussed above. The systematic bits consist of the DCI message and the CRC of the DCI message. Each repetition can be decoded separately because they all contain a complete set of systematic bits and have some parity bits to aid in decoding. However, by combining repetition, the code rate decreases and the decoding capability increases.

Fig. 5 shows an example in which three repetitions of PDCCH are transmitted in three different monitoring occasions of CORESET 1 (i.e., each repetition is in the same CORESET). As explained with respect to fig. 4, each repetition consists of a systematic bit and a set of different parity bits. After the first monitoring occasion 1, the UE attempts to blind decode the PDCCH. If the PDCCH in the listening occasion 2 cannot be decoded blindly, the UE performs soft combining on the first two repetitions to reduce the code rate (due to the different parity bits in the two repetitions), and improves the prospect of decoding the PDCCH. If the decoding is still unsuccessful, the third repetition may be used for blind decoding or soft combining with the previous two repetitions.

In an alternative arrangement, the systematic bits are transmitted only in the initial transmission of the PDCCH and the parity bits are transmitted in all repetitions.

The systematic bits of the PDCCH are the DCI and CRC portions of the message and may be encoded with a higher aggregation level (i.e., lower code rate) than each individual repetition. The coded bits are then punctured into different parts according to the number of repetitions, with transmission at a lower aggregation level than that used for a single transmission. The system and the first part of the code bits are transmitted in an initial transmission at a lower aggregation level and the remaining code bits are transmitted in other binding search spaces, which may be located in the same or different monitoring occasions of the same or different CORESET. In practice, a larger search space with a larger aggregation level is constructed from a subset of the search spaces with a lower aggregation level.

For example, as shown in fig. 6, systematic bits can be encoded using an aggregation level L. When two repetitions are configured for the PDCCH, the coded bits are split into two parts, each part having an aggregation level of L/2. The first part is transmitted in an initial transmission and the second part is transmitted at another occasion of PDCCH transmission. In this approach, only the first transmission is self-decodable because the systematic bits are not repeated in the second transmission. However, additional parity bits in subsequent transmissions may be used to aid in decoding.

Fig. 7 shows an example in which two repetitions are sent at two different monitoring occasions of two different CORESETs (CORESET 1 and CORESET 2). The signal transmitted in each repetition may be defined in accordance with the principles described herein. The UE blindly detects the first PDCCH transmission at listening occasion 1 of CORESET 1. If the first transmission part of the PDCCH is not decoded, the UE will attempt to find the second part of the PDCCH transmission at listening occasion 2 of CORESET 2. The indication of two binding search spaces may be configured using a static predefined mode function or a semi-static configuration, as described below. The UE may then perform soft combining with the first part to obtain PDCCH transmissions with higher aggregation levels.

The advantage of this arrangement is that the systematic bits are transmitted only once compared to the previous proposal with systematic bits in each repetition. Thus, PDCCH repetition with search space aggregation may achieve additional coding rate gains due to the transmission of more parity bits in the repetition. Thus increasing reliability and this will increase coverage. The type of soft combining may be defined in the configuration of PDCCH repetition, which will be discussed below.

CCE indexes of the bundled search space for PDCCH repetition may be defined by a function of CCE indexes of the initial PDCCH transmission, CORESET size, number of repetitions, and aggregation level of the relevant search space.

The parameters of the bundled CORESET size, the aggregation level of the bundled search space, and the number of repetitions may be set by RRC signaling. The UE performs blind decoding on the first PDCCH transmission and the CCE index of this initial transmission is obtained by a hashing function (e.g., as defined in TS 38.213). The following retransmitted candidate will be associated with the first candidate. Thus, a function may be defined to calculate the CCE index of the bundled search space as:

CCE index _Binding =f (CCE index) _{Initial initiation} CORESET size, number of repetitions, aggregation level) (1)

As described above, two specific arrangements for binding a search space are disclosed herein:

i. two different sets of search spaces are configured on the same CORESET and their association is indicated to the UE for PDCCH repetition purposes.

A single set of search spaces is configured and the PDCCH is repeated on different instances of the same set of search spaces. The PDCCH configuration indicates to the UE which blind decoding it will perform to jointly decode the PDCCH from two instances of the search space.

A second scheme to perform PDCCH repetition on different CORESETs would necessarily require two search spaces, as each search space is associated with a single different CORESET.

The PDCCH configuration message sent to the UE as part of the PDCCH configuration indicates the use of PDCCH repetition, e.g., by including a flag. The PDCCH configuration also indicates whether repetition is to be transmitted on a single set of search spaces or two different sets of search spaces. The PDCCH configuration may indicate an identification of a search space to be used.

The configuration of each search space may include binding information. The flag may indicate whether the configured search space may have repetition of the PDCCH. When the search space is bundled with a different search space, the search space may have an indication that this is to be bundled with the search space for PDCCH repetition. This may be accomplished by indicating a field as part of the search space configuration, the field providing an identification of other search spaces.

Generalizing the configuration to additional search space and providing additional flexibility, the configuration of the bonded search space for different scenarios of PDCC repetition may be indicated by the following two methods. These can be applied with minor adjustments to the three schemes presented above.

In a first method, a pattern of a set of bundled search spaces with different aggregation levels for PDCCH repetition may be predefined by the network and may be provided to the UE through RRC signaling.

The binding search space may be configured with RRC signaling including aggregation level, number of repetitions, resource size, and monitoring occasion location. Only one configuration of the predefined binding search space is repeated for the PDCCH. This configuration would then be applied periodically to PDCCH repetition. The configuration parameters of each search space cannot be dynamically changed during transmission.

CCE indexes of candidates in the bundled search space may be associated with candidates in the initial search space. It can be calculated by the function (1) defined above. An example mapping function that binds the search space is provided below. The CCE index calculation function of the bundling candidate may be defined as:

CCE index _Binding = { (CCE index) _{Initial initiation} /L _{Initial initiation} +CCE_offset)mod(S _Binding /L _Binding )}*(L _Binding ) (2)

Wherein:

S _binding Is a bonded search space size according to the number of CCEs,

CCE_offset∈{0,1,..,min((S _{initial initiation} /L _{Initial initiation} ),(S _Binding /L _Binding ))-1},

L _Binding Is the aggregation level of the binding search space,

L _{initial initiation} Is the aggregate level of the initial search space,

CCE index initial values are calculated using the hash function (2) defined in TS 38.213.

Parameter CCE_offset, L _{Initial initiation} 、L _Binding And S is _Binding May be configured through RRC signaling. CCE index _{Initial initiation} Can be obtained by a hash function (3) for the first blind decoding. Function (2) can then be used to bind the search spaceThe following association candidates in (a) calculate CCE index bindings. The parameter cce_offset provides more flexibility for resource allocation for PDCCH transmission in the search space bundles.

In the second method, a plurality of configurations of PDCCH repetition based on the search space bundle may be configured through RRC signaling. The network may limit the number of active configurations to reduce the blind decoding requirements of the UE. Configuration IDs may also be associated with different sequences of PDCCH DMRS. In this case, only one configuration is enabled per PDCCH transmission, but can be dynamically updated from one transmission to another by altering the sequence of PDCCH DMRS.

Aggregation level, search space size, CCE index per bonded search space, and soft combining type may be configured through RRC signaling. When the PDCCH is configured to repeat, the blind decoding requirement increases. If all combining options are used, it may result in the maximum number of blind decodes. Therefore, the number of combinations should be limited. One solution is that the network may schedule certain predefined configurations with combinations of different aggregation levels in the search space. Thus, due to the merging, there is still a certain amount of blind decoding, but the complexity is limited.

Another solution is to enable only one configuration dynamically during each PDCCH transmission. Different sequences of PDCCH DMRS are associated with different binding configurations. Thus, the configuration ID may be identified by performing a different sequence of association functions of PDCCH DMRS. This approach provides the network with greater flexibility in terms of resource management than the predefined pattern used in proposal 2. The network may schedule PDCCH repetitions with different combinations according to the currently available resources in the search space.

For example, the network schedules one PDDCH initial transmission and two repetitions by a combination of different aggregation levels (AL 4, AL8, and AL 16). Table 1 lists four possible configurations. If the search space of AL8 is available at the first monitoring occasion, the network may employ configuration 2 or 3. If it deems it appropriate to reserve AL4 and AL8, it will use configuration 2. If the channel conditions are poor and the network decides to use AL8 and AL16, it can use configuration 3. Otherwise, configuration 0 or 1 may schedule initial transmission according to available resources repeated per PDCCH. Some of the combined gains are obtained by time domain repetition.

Therefore, it can improve the coverage.

Configuration index	Initial transmission	Repeat	1	Repeat 2
					0	AL4	AL8	AL4
1	AL4	AL4	AL8
					2	AL8	AL4	AL4
3	AL8	8	AL16

TABLE 1

In such a scheme, the DMRS will indicate the configuration index, so the UE will know which configuration is active. It may then use the known configuration of the bundled search space to repeatedly perform joint decoding on the actively configured PDCCH.

In summary, PDCCH repetition may be performed on different CORESETs, using bundled search spaces in different aggregation levels to enhance coverage. The CCE indexes of the bundled search space are associated with CCE indexes of the initial search space. The method is more flexible in terms of PDCCH scheduling with different configuration methods. Different PDCCH repetition methods provide more flexibility for resource management and reduce the likelihood of blocking problems.

Although not shown in detail, any device or apparatus that forms part of the network may include at least a processor, memory, and a communication interface, wherein the processor, memory, and communication interface are configured to perform the following methods: any aspect of the invention. Further options and selections are described below.

The signal processing functions of embodiments of the present invention, particularly the gNB and the UE, may be implemented using computing systems or architectures known to those skilled in the relevant art. Computing systems, such as desktop, laptop or notebook computers, hand-held computing devices (PDAs, cell phones, palmtops, etc.), mainframes, servers, clients, or any other type of special or general purpose computing device may be desirable or appropriate for a given application or environment. A computing system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine, such as a microprocessor, microcontroller, or other control module.

The computing system may also include a main memory, such as Random Access Memory (RAM) or other dynamic memory, for storing information and instructions to be executed by the processor. Such main memory may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system, which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, floppy disk drive, magnetic tape drive, optical disk drive, compact Disk (CD) or Digital Video Drive (DVD) (RTM) read or write drive (R or RW), or other removable or fixed media drive. Storage media may include, for example, hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by a media drive. The storage medium may include a computer-readable storage medium having stored therein specific computer software or data.

In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, removable storage units and interfaces such as program cartridge and cartridge interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computing system.

The computing system may also include a communication interface. Such a communication interface may be used to allow software and data to be transferred between the computing system and external devices. Examples of communication interfaces may include modems, network interfaces (e.g., ethernet or other NIC cards), communication ports (e.g., universal Serial Bus (USB) ports), PCMCIA slots and cards, etc. Software and data transferred via the communications interface are in the form of signals which may be electronic, electromagnetic and optical or other signals capable of being received by the communications interface medium.

In this document, the terms "computer program product," "computer-readable medium," and the like may be used to generally refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor constituting a computer system to cause the processor to perform specified operations. Such instructions, generally 45, are referred to as "computer program code" (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause the processor to perform the specified operation, be compiled to do so, and/or be combined with other software, hardware, and/or firmware components (e.g., libraries for performing standard functions) to do so.

The non-transitory computer readable medium may include at least one from the group consisting of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments where the components are implemented using software, the software may be stored in a computer readable medium and loaded into a computing system using, for example, a removable storage drive. The control module (in this example, software instructions or executable computer program code) when executed by a processor in a computer system causes the processor to perform the functions of the invention as described herein.

Furthermore, the inventive concept may be applied to any circuit for performing signal processing functions within a network element. It is further contemplated that, for example, a semiconductor manufacturer may employ the concepts of the invention in the design of a stand-alone device, such as a microcontroller of a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC), and/or any other subsystem component.

It should be appreciated that for clarity, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by a number of different functional units and processors to provide a signal processing function, and thus references to specific functional units are only to be seen as references to suitable means for providing the described function, rather than indicative of a strict logical or physical structure or organization.

Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices.

Thus, the components and elements of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed, and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second", etc. do not exclude a plurality.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" or "comprises" does not exclude the presence of other elements.

Claims

1. A method of transmitting downlink control information in a cellular communication network using an OFDM transmission format, comprising:

defining a search space bundle for transmitting downlink control channels, wherein the search space bundle comprises control channel elements of at least two monitoring occasions; and

Transmitting a downlink control channel in a control channel element of a first one of the at least two monitoring occasions and transmitting a repetition of at least part of the downlink control channel in a control channel element of a second one of the at least two monitoring occasions.

2. The method of claim 1, wherein the transmissions in the first monitoring occasion use a different aggregation level than the transmissions in the second monitoring occasion.

3. The method of claim 1 or 2, wherein the repetition repeats systematic bits of the downlink control channel and comprises parity bits that are different from the first transmission.

4. A method according to any preceding claim, wherein the control channel elements of the first and second monitoring occasions are in the same CORESET.

5. The method of claim 4, wherein the search space bundle includes at least one set of search spaces set in CORESET for each monitoring occasion.

6. The method of claim 5, further comprising the step of transmitting an indication of an association between at least two search spaces.

7. The method of claim 6, wherein the indication allows the UE to decode the repetition without blind decoding.

8. The method of claim 1, wherein the search space bundle comprises a single set of search spaces set at each monitoring occasion.

9. A method according to any one of claims 1 to 3, wherein the control channel elements of the first and second monitoring occasions are in different cores.

10. The method of any preceding claim, wherein the repetition comprises a subset of bits transmitted in the first transmission, the method further comprising transmitting a second repetition of at least a portion of the downlink control channel, wherein the second repetition comprises a different subset than the subset transmitted in the first repetition.

11. The method of claim 10, wherein the location of the control channel element of the second monitoring occasion is related to the location of the control channel element of the first monitoring occasion.

12. The method of any preceding claim, further comprising transmitting information about the search space bundle.

13. The method of claim 12, wherein the information comprises an indication of how the location of the control channel component of the second monitoring occasion relates to the location of the control channel component of the first monitoring occasion.

14. The method of claim 12, wherein the information includes an identification of CORESET containing the control channel element that is bonded.

15. The method of claim 14, wherein the CORESET is identified by a particular CORESET ID.

16. The method of claim 15, wherein the particular CORESET ID is defined based on a CORESET ID of the CORESET contained in the search space bundle.

17. The method of claim 3, wherein the systematic bits are bits representing a DCI message and a CRC.

18. The method of any preceding claim, wherein CCE indexes of the control channel elements used by the second monitoring occasion are defined by a function of CCE indexes of the control channel elements used by the first monitoring occasion.

19. The method of claim 18, wherein the function is:

20. A method of transmitting downlink control information in a cellular communication network using an OFDM transmission format, comprising:

Defining a search space bundle for transmitting a downlink control channel, wherein the search space bundle comprises at least two control channel elements of CORESET in a single monitoring occasion; and

transmitting a downlink control channel in a control channel element of a first one of the at least two CORESETs and transmitting a repetition of at least a portion of the downlink control channel in a control channel element of a second one of the at least two CORESETs.

21. The method of claim 20 wherein the transmissions in the first CORESET use a different aggregation level than the transmissions in the second CORESET.

22. The method of claim 20 or 21, wherein the repetition repeats systematic bits of the downlink control channel and comprises parity bits that are different from the first transmission.

23. The method of any of claims 20-22, wherein the repetition comprises a subset of bits transmitted in the first transmission, the method further comprising transmitting a second repetition of at least a portion of the downlink control channel, wherein the second repetition comprises a different subset than the subset transmitted in the first repetition.

24. The method according to any one of claims 20 to 23, wherein the location of the control channel component of the second CORESET is related to the location of the control channel component of the first CORESET.

25. The method of any of claims 20 to 24, further comprising transmitting information about the search space bundle.

26. The method of claim 25, wherein the information includes an indication of how the location of the control channel component of the second CORESET relates to the location of the control channel component of the first CORESET.

27. A method according to claim 25 or 26, wherein the information comprises an identification of CORESET containing the control channel component to which it is bonded.

28. The method of claim 27, wherein the CORESET is identified by a particular CORESET ID.

29. The method of claim 28, wherein the particular CORESET ID is defined based on a CORESET ID of the CORESET contained in the search space bundle.

30. The method of claim 22, wherein the systematic bits are bits representing a DCI message and a CRC.

31. The method according to any one of claims 16 to 20, wherein CCE indexes of the control channel component used by the second CORESET are defined by a function of CCE indexes of the control channel component used by the first CORESET.

32. The method of claim 31, wherein the function is:

33. A method performed at a UE in a cellular communication network using an OFDM transmission format, comprising:

defining a search space bundle for receiving a downlink control channel, wherein the search space bundle comprises control channel components of at least two monitoring occasions; and

receiving a downlink control channel in a control channel component of a first one of the at least two monitoring occasions and receiving a repetition of at least a portion of the downlink control channel in a control channel component of a second one of the at least two monitoring occasions.

34. The method of claim 33, wherein receiving the transmission in the first monitoring occasion uses a different aggregation level than receiving the transmission in the second monitoring occasion.

35. The method of claim 33 or 34, wherein the repetition repeats systematic bits of the downlink control channel and comprises parity bits that are different from the first transmission.

36. The method according to any one of claims 33 to 35, wherein the control channel components of the first and second monitoring occasions are in the same CORESET.

37. The method of claim 36, wherein the search space bundle includes at least one search space set in CORESET for each monitoring occasion.

38. The method of claim 37, further comprising the step of transmitting an indication of an association between at least two search spaces.

39. The method of claim 38, wherein the indication allows the UE to decode the repetition without blind decoding.

40. The method of claim 33, wherein the search space bundle comprises a single set of search spaces set at each monitoring occasion.

41. A method according to any one of claims 33 to 36, wherein the control channel components of the first and second monitoring occasions are in different cores.

42. The method of any of claims 33-41, wherein the repetition comprises a subset of bits transmitted in the first transmission, the method further comprising receiving a second repetition of at least a portion of the downlink control channel, wherein the second repetition comprises a different subset than the subset transmitted in the first repetition.

43. The method of any of claims 33-42, wherein the location of the control channel component of the second monitoring occasion is related to the location of the control channel component of the first monitoring occasion.

44. The method of any one of claims 33 to 43, further comprising receiving information about the search space bundles.

45. The method of claim 44, wherein the information comprises an indication of how the location of the control channel component of the second monitoring occasion relates to the location of the control channel component of the first monitoring occasion.

46. The method of claim 44 or 45, wherein the information includes an identification of CORESET containing the control channel component to which it is bonded.

47. The method of claim 46, wherein the CORESET is identified by a particular CORESET ID.

48. The method of claim 47, wherein the particular CORESET ID is defined based on a CORESET ID of the CORESET contained in the search space bundle.

49. The method of claim 35, wherein the systematic bits are bits representing a DCI message and a CRC.

50. The method of any of claims 33-49, wherein CCE indexes of the control channel component used by the second monitoring occasion are defined by a function of CCE indexes of the control channel component used by the first monitoring occasion.

51. The method of claim 50, wherein the function is:

52. The method of any of claims 33 to 51, wherein the UE blindly decodes the first transmission and decodes the second transmission based on the received indication.

53. A method performed at a UE in a cellular communication network using an OFDM transmission format, comprising:

Defining a search space bundle for receiving a downlink control channel, wherein the search space bundle comprises at least two control channel components of CORESET in a single monitoring occasion; and

a downlink control channel is received in a control channel component of a first one of the at least two CORESETs and a repetition of at least a portion of the downlink control channel is received in a control channel component of a second one of the at least two CORESETs.

54. The method of claim 53, wherein receiving transmissions in a first CORESET uses a different aggregation level than receiving transmissions in a second CORESET.

55. The method of claim 53 or 54, wherein the repetition repeats systematic bits of the downlink control channel and comprises parity bits that are different from the first transmission.

56. The method of any of claims 53-55, wherein the repetition comprises a subset of bits transmitted in the first transmission, the method further comprising transmitting a second repetition of at least a portion of the downlink control channel, wherein the second repetition comprises a different subset than the subset transmitted in the first repetition.

57. A method according to any one of claims 53 to 56, wherein the location of the control channel component of the second CORESET is related to the location of the control channel component of the first CORESET.

58. The method of any one of claims 53 to 57, further comprising transmitting information about the search space bundles.

59. A method according to claim 58 wherein the information includes an indication of how the location of the control channel component of the second CORESET relates to the location of the control channel component of the first CORESET.

60. The method of claim 58 or 59, wherein the information includes an identification of CORESET containing the control channel component to which it is bonded.

61. The method of claim 60, wherein the CORESET is identified by a particular CORESET ID.

62. The method of claim 61, wherein the particular CORESET ID is defined based on a CORESET ID of the CORESET contained in the search space bundle.

63. The method of claim 55 wherein the systematic bits are bits representing a DCI message and a CRC.

64. The method of any one of claims 53 to 63, wherein CCE indexes of the control channel component used by the second CORESET are defined by a function of CCE indexes of the control channel component used by the first CORESET.

65. The method of claim 64, wherein the function is:

66. The method of any of claims 53-65, wherein the UE blindly decodes the first transmission and decodes the second transmission based on the received indication.

67. A base station configured to perform the method of any of claims 1 to 32.

68. A UE configured to perform the method of any one of claims 33 to 66.