WO2021189387A1

WO2021189387A1 - Methods, devices, and medium for communication

Info

Publication number: WO2021189387A1
Application number: PCT/CN2020/081514
Authority: WO
Inventors: Lin Liang; Gang Wang
Original assignee: Nec Corporation
Priority date: 2020-03-26
Filing date: 2020-03-26
Publication date: 2021-09-30

Abstract

According to embodiments of the present disclosure, if a terminal device supports a low complexity mode, the terminal device determines at least one of: a limited number of downlink control channel candidates in a time slot or a limited number of control channel elements in the time slot. The terminal device monitors at least one downlink control channel candidate or control channel element from the limited number of downlink control channel candidates or the limited number of control channel elements and decode downlink control information on the monitored downlink control channel candidate or the monitored control channel element. In this way, balance between flexibility and capability can be achieved.

Description

METHODS, DEVICES, AND MEDIUM FOR COMMUNICATION

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods, devices, and medium for communication.

BACKGROUND

Communication technologies have been developed, for example, new radio (NR) . A network device may transmit information on downlink control channel. A terminal device needs to monitor the downlink control channel to obtain the information. It is significantly important whether the terminal device can decode the information correctly. Thus, solutions on a tradeoff between flexibility and capability needs to be further studied. However, according to conventional technologies, the reduction of downlink control channel candidate has not been discussed.

SUMMARY

In general, example embodiments of the present disclosure provide a solution of downlink control channel candidates priority and reduction.

In a first aspect, there is provided a method for communication. The method comprises in accordance with a determination that a terminal device supports a low complexity mode, determining, at the terminal device, at least one of: a limited number of downlink control channel candidates in a time slot or a limited number of control channel elements in the time slot. The method further comprises monitoring at least one downlink control channel candidate or control channel element from the limited number of downlink control channel candidates or the limited number of control channel elements. The method also comprises decoding downlink control information on the monitored downlink control channel candidate or the monitored control channel element.

In a second aspect, there is provided a method for communication. The method comprises determining, at a network device, at least one of a limited number of downlink control channel candidates or a limited number of control channel element which is applicable to a terminal device supported a low complexity mode. The method also comprises transmitting to a terminal device information indicating at least one of the limited number of downlink control channel candidates or the limited number of control channel elements.

In a third aspect, there is provided a terminal device. The terminal device comprises a processing unit; and a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the terminal device to perform in accordance with a determination that a terminal device supports a low complexity mode, determining, at the terminal device, at least one of: a limited number of downlink control channel candidates in a time slot or a limited number of control channel elements in the time slot; monitoring at least one downlink control channel candidate or control channel element from the limited number of downlink control channel candidates or the limited number of control channel elements; and decoding downlink control information on the monitored downlink control channel candidate or the monitored control channel element.

In a fourth aspect, there is provided a network device. The network device comprises a processing unit; and a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the network device to perform determining, at a network device, at least one of a limited number of downlink control channel candidates or a limited number of control channel element which is applicable to a terminal device supported a low complexity mode; and transmitting to a terminal device information indicating at least one of the limited number of downlink control channel candidates or the limited number of control channel elements.

In a fifth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to any one of the first aspect, second aspect, third aspect, fourth aspect or fifth aspect.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some example embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 is a schematic diagram of a communication environment in which embodiments of the present disclosure can be implemented;

Fig. 2 is a flowchart of an example method in accordance with an embodiment of the present disclosure;

Fig. 3 is a flowchart of an example method in accordance with an embodiment of the present disclosure;

Fig. 4 is a signaling chart illustrating a process according to an embodiment of the present disclosure;

Fig. 5 is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an Evolved NodeB (eNodeB or eNB) , a NodeB in new radio access (gNB) a Remote Radio Unit (RRU) , a radio head (RH) , a remote radio head (RRH) , a low power node such as a femto node, a pico node, a satellite network device, an aircraft network device, and the like. For the purpose of discussion, in the following, some example embodiments will be described with reference to eNB as examples of the network device.

As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, or image capture devices such as digital cameras, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

In one embodiment, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In one embodiment, the first network device may be a first RAT device and the second network device may be a second RAT device. In one embodiment, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device and the second network device. In one embodiment, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In one embodiment, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

Communications discussed herein may use conform to any suitable standards including, but not limited to, New Radio Access (NR) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , cdma2000, and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.85G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies.

As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to. ” The term “based on” is to be read as “based at least in part on. ” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment. ” The term “another embodiment” is to be read as “at least one other embodiment. ” The terms “first, ” “second, ” and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as “best, ” “lowest, ” “highest, ” “minimum, ” “maximum, ” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

In communication system, for example, long-term-evolution (LTE) or new radio (NR) , resources for physical control information are shared between terminal devices. Downlink Control Information (DCI) may be transmitted on PDCCH. The terminal device should periodically decode PDCCH among many PDCCH candidates of the terminal device.

The PDCCH candidates are configured by control resource set (CORESET) and Search Space through radio resource control configuration. Search Space configure the number of PDCCH candidates per aggregation level. For example, there are total 40 control channel element (CCE) , the aggregation level is L and the PDDCCH candidate number is N.

Search Space has different types, e.g. Common Search Space (CSS) and UE Search Space (USS) . Due to the different periodicity of CSS and USS, they may overlap on some slots. CSS should have higher priory than USS.

Generally, a terminal device may not be expected to blind decode many PDCCH candidates due to its capability, so maximum number of candidates. Number of candidates for CSS should be less than maximum number of candidates for a terminal device. If the number of candidates for a USS plus existing candidates set, that USS will not be decoded at this slot. For example, CSS candidates are 20, USS candidates are 30, maximum candidates are 44, then USS will not be detected in this slot.

The more number of PDCCH candidates and CCE, the more flexibility of PDCCH decoding among lots of UEs. When the PDCCH occasions for different terminal devices collide in a slot, more candidates give opportunity for terminal device to change the occasion of a PDCCH. On the other hand, more number of PDCCH candidates mean more polar decoding attempt, and more CCE means more channel estimation and demodulation on the CCE, which will increase the UE capability. Thus, solution on a tradeoff between flexibility and capability needs to be further studied. However, according to convention technologies, the reduction of downlink control channel candidate has not been discussed.

In order to solve at least part of the aforementioned problems, new technologies in downlink control channel candidates priority and reduction are needed. According to embodiments of the present disclosure, if a terminal device supports a low complexity mode, the terminal device determines at least one of: a limited number of downlink control channel candidates in a time slot or a limited number of control channel elements in the time slot. The terminal device monitors at least one downlink control channel candidate or control channel element from the limited number of downlink control channel candidates or the limited number of control channel elements and decode downlink control information on the monitored downlink control channel candidate or the monitored control channel element. In this way, balance between flexibility and capability can be achieved.

Fig. 1 illustrates a schematic diagram of a communication system in which embodiments of the present disclosure can be implemented. The communication system 100, which is a part of a communication network, comprises a terminal device 110-1, a terminal device 110-2, ..., a terminal device 110-N, which can be collectively referred to as “terminal device (s) 110. ”

The communication system 100 further comprises a network device 120. In the communication system 100, the network devices 110 and the terminal devices 120 can communicate data and control information to each other. The numbers of terminal devices and network devices shown in Fig. 1 are given for the purpose of illustration without suggesting any limitations.

Communications in the communication system 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Divided Multiple Address (CDMA) , Frequency Divided Multiple Address (FDMA) , Time Divided Multiple Address (TDMA) , Frequency Divided Duplexer (FDD) , Time Divided Duplexer (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Divided Multiple Access (OFDMA) and/or any other technologies currently known or to be developed in the future.

Embodiments of the present disclosure will be described in detail below. Fig. 2 shows a flowchart of an example method 200 in accordance with an embodiment of the present disclosure. Only for the purpose of illustrations, the method 200 can be implemented at a terminal device 110-1 as shown in Fig. 1.

In some embodiments, the terminal device 110-1 can monitor a set of PDCCH candidates in one or more CORESETs on an active downlink (DL) bandwidth part (BWP) on each activated serving cell according to corresponding search spaces, where monitoring implies or refers to decoding (or attempting to decode) some or all PDCCH candidates in the PDCCH candidate set according to the monitored Downlink Control Information (DCI) formats. A set of PDCCH candidates for the terminal device 110-1 to monitor can be defined in terms of PDCCH search spaces. A search space can be a common search space (CSS) or a UE-specific search space (USS) . According to current NR implementations, the terminal device 110-1 can monitor PDCCH candidates in non-discontinuous reception (DRX) slots (or slots) in one or more of the various defined search spaces.

For PDCCH monitoring purposes, each BWP configured to the terminal device 110-1 can be associated with up to about three CORESETs and up to ten search space sets. In particular, the number of PDCCH candidates per aggregation level (AL) can be independently configured among {0, 1, 2, 3, 4, 5, 6, 8} for each search space (SS) . Monitoring periodicities of different SS sets can be different and be selected from a set of possible values given as {1, 2, 4, 5, 8, 10, 16, 20} slots, for example.

In some embodiments, the terminal device 110-1 may support different modes. In some embodiments, the terminal device 110-1 may support a normal capability mode. Alternatively, the terminal device 110-1 may support a low complexity mode. Only as an example, in 5G communication systems, there are serval scenarios, for example, enhanced mobile broadband (eMBB) , massive machine-type communication (mMTC) , and Ultra-Reliable and Low Latency communication (URLLC) . In some embodiments, if the terminal device 110-1 is in the scenario of massive machine-type communication, the terminal device 110-1 may need to save power. Thus, the terminal device 110-1 may support the low complexity mode. In some embodiments, the terminal device 110-1 may transmit information indicating its support mode. The supported mode may be reported by an arbitrary number or within a predefined set in specification. For example, the terminal device 110-1 may transmit the information indicating “1” to inform the network device 120 that the terminal device 110-1 may support the low complexity mode.

At block 210, the terminal device 110-1 determines a limited number of downlink control channel candidate and/or a limited number of control channel elements in a time slot if the terminal device 110-1 supports the low complexity mode. In this way, the balance between flexibility and capability can be achieved. Further, power of the terminal device 110-1 can be saved without degrading performances.

For the purpose of illustrations, the downlink control channel used hereinafter may refer to physical downlink control channel (PDCCH) . It should be noted that the downlink control channel may refer to other suitable downlink control channel. The control channel element (CCE) is a group of resources which can be used to send a PDCCH. The aggregation level of the CCE may be 1, 2, 4 or 8. For example, 1, 2, 4 or 8 CCEs can be grouped to support larger messages. A control-channel element consists of 6 resource-element groups (REGs) where a resource-element group equals one resource block during one OFDM symbol. A PDCCH candidate may comprise consecutive CCES.

In some embodiments, the terminal device 110-1 may receive information indicating the limited number of downlink control channel candidate and/or the limited number of CCEs. For example, the information may be transmitted via radio resource control (RRC) signaling. In some embodiments, the ueCapabilityInformation message may comprise a new domain “maxPdcchCandidates” which indicates the limited number of PDCCH candidates. Alternatively, the ueCapabilityInformation message may comprise another domain “maxPdcchCCE” which indicates the limited number of CCEs. In other embodiments, the limited number of PDCCH candidates and the limited number of CCEs may be indicated by “maxPdcchCandidates” and “maxPdcchCCE” in the UEAssistanceInformation, respectively. The network device 120 may configure “maxPdcchCandidates” and “maxPdcchCCE” to be used by the terminal device 110-1 based on information of the low complexity. In some embodiments, the network device 120 may still configure the “maxPdcchCandidates” and “maxPdcchCCE” to the terminal device 110-1 even if the terminal device 110-1 informs its capability.

In other embodiments, the terminal device 110-1 may determine the limited number of PDCCH candidates and/or the limited number of CCEs from predetermined configuration. For example, the predetermined configuration may be preconfigured to the terminal device 110-1. If the terminal device 110-1 needs to be in the low complexity mode, the terminal device 110-1 may determine the limited number of PDCCH candidates and/or the limited number of CCEs from predetermined configuration.

Tables 1-5 show the limited number of PDCCH candidates. It should be noted that the limited number of PDCCH candidates shown in Tables 1-5 are only examples not limitations. For example, the existing number for u=1 may be shifted into new table for u=0. The limited number of PDCCH candidates may be any suitable integer numbers.

Table 1

u	The limited number of PDCCH candidates
0	36
1	33
2	20
3	18

Table 2

u	The limited number of PDCCH candidates
0	36
1	33
2	20
3	16

Table 3

u	The limited number of PDCCH candidates
0	36
1	33
2	20
3	12

Table 4

u	The limited number of PDCCH candidates
0	22
1	20
2	18
3	16

Table 5

u	The limited number of PDCCH candidates
0	22
1	20
2	16

3

12

Tables 6-10 show the limited number of CCEs. It should be noted that the limited number of CCEs candidates shown in Tables 6-10 are only examples not limitations.

Table 6

u	The limited number of CCEs
0	56
1	48
2	32
3	32

Table 7

u	The limited number of CCEs
0	56
1	48
2	32
3	24

Table 8

u	The limited number of CCEs
0	48
1	32
2	32
3	24

Table 9

u	The limited number of CCEs

0	48
1	32
2	24
3	16

Table 10

u	The limited number of CCEs
0	48
1	32
2	32
3	16

In some embodiments, for higher frequency operation, larger sub carrier space (SCS) may be introduced. Tables shown the limited number of PDCCH candidates or CCE can be extended. Such tables may be preconfigured at the terminal device 110-1 and the network device 120. Alternatively, such tables can be transmitted from the network device 120 to the terminal device 110-1. Tables 11 and 12 are extended tables showing the limited number of PDCCH candidates. It should be noted that the limited number of PDCCH candidates shown in Tables 11 and 12 are only examples not limitations.

Table 11

u	The limited number of PDCCH candidates
0	44
1	36
2	22
3	30
4	18
5	16

Table 12

u	The limited number of PDCCH candidates
0	44
1	36
2	22
3	30
4	16
5	12

Tables 13 and 14 are extended tables showing the limited number of CCEs. It should be noted that the limited number of CCEs shown in Tables 13 and 14 are only examples not limitations.

Table 13

u	The limited number of CCEs
0	56
1	56
2	48
3	32
4	32
5	24

Table 14

u	The limited number of CCEs
0	56
1	56
2	48

3	32
4	24
5	16

At block 220, the terminal device 110-1 monitors at least one downlink control channel candidate or CCE. In some examples, the terminal device 110-1 may monitor all of the limited number of downlink channel candidates. Alternatively, the terminal device 110-1 may monitor all of the limited number of CCEs.

In some embodiments, the terminal device 110-1 may not monitor all of the PDCCH candidates or CCEs. The priority information between the PDCCH candidates may be used. Alternatively, the priority information between the CCEs may also be used. The priority information may be determined by the network device 120 and transmitted to the terminal device 110-1. In this way, the terminal device 110-1 is able to monitor the PDCCH or CCE with higher priority. For example, if a UE Search Space (USS) may need M candidates and there is only N candidate left where M>N, the whole candidates in the USS cannot decoded by the terminal device 110-1. In such situation, the terminal device 110-1 may select the PDCCH candidate based on the priority information.

For example, the priority information may be transmitted via the RRC signaling. The priority information may be configured based on aggregation level of the PDCCH candidate and/or the CCE. The priority information may indicate that the priority of the aggregation levels may be 2>4>1>8. In this way, it is beneficial for the network device 120 aware downlink control information (DCI) scheduling based on coverage of the terminal device 110-1.

In other embodiments, the priority information may be associated with the low complexity mode. For example, if the terminal device 110-1 supports the low complexity mode, the priority information may indicate that the priority of the aggregation levels may be 8>4>2>1. In this way, it is better for the UE coverage.

Alternatively or in addition, the propriety information may be associated with index of each aggregation level. Only as an example, index 0 in each aggregation level may have higher priority than index 1 in each aggregation level. Therefore, this will give opportunity for each aggregation level by scheduling.

In some embodiments, score factor can be introduced for different aggregation level (L) , different PDCCH candidate index in aggregation level (k) ) , different USS (j) . In some embodiments, the less score represents the higher priority. Alternatively, the more score represents higher priority which is based on the definition of score.

In some embodiments, the score may be obtained based on log2 (L) *A+ k*B + j*C, where A, B, C is RRC configured parameter. When C >= 8*B + 4*A, then USS index has the highest priority, i.e. priority order is based on USS index. When B >= 4*A, then it’s aggregation level first order, i.e. the index 0 for aggregation level 1, 2, 4, 8 candidates first. When A >= 8*B, then it’s index first order, L with the value 1 has higher priority than L with the value 2. When A <= -8*B, then it’s index first order, L with the value 1 has lower priority than L with the value 2.

In other embodiments, the score may be obtained based on A (log2 (L) ) + k*B, where A (n) is RRC configured parameter per aggregation level. RRC can configure the A (n) per aggregation level, as channel condition for a terminal device prefers to some specific aggregation level, e.g. L priority is 4 > 2 > 1 > 8 leads to A (2) > A (1) > A (0) > A (3) . It should be noted that the missing USS index j and parameter C or C (j) can be added. If not, means USS index have the highest priority among L and k.

Alternatively, the score may be obtained A (log2 (L) ) + k*B (log2 (L) ) , where A (n) and B (n) is RRC configured parameter per aggregation level. When A (n) = 0 for all L and B (n) = 1/ (M (L) ) , where M (L) is the configured number of candidates for L, then scaling for each L is used. For example, L=1, 2, M (1) = 8, M (2) = 4. The needed candidates is 12, however only 6 candidates left. The score for the 12 candidates is 0, 1/8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8, 0, 1/4, 2/4, 3/4. The chosen candidates pairs (L, K) are (1, 0) , (1, 1) , (1, 2) , (1, 3) , (2, 0) , (2, 1) which is the scaling of the original candidates. Alternatively, the score may be obtained D (L, k) , where D (L, k) is RRC configured priority for aggregation level L and candidate index k for L.

At block 230, the terminal device 110-1 decodes downlink control information on the monitored downlink channel candidate and/or the CCE. For example, if the terminal device 110-1 monitors all of the limited number of PDCCH candidates and/or CCEs, the terminal device 110-1 may decode the downlink control information on all of the PDCCH candidates and/or CCEs. Alternatively or in addition, the terminal device 110-1 may decode the downlink control information on the downlink channel candidate and/or the CCE monitored based on the priority information.

According to embodiments of the present disclosure, it can achieve balance between flexibility and capability. Power and battery life of the terminal device can be saved. Further, the priority between downlink control channel candidates or the CCEs can be configured based on specific situations, thereby achieving better performance.

Fig. 3 shows a flowchart of an example method 300 in accordance with an embodiment of the present disclosure. Only for the purpose of illustrations, the method 300 can be implemented at a network device 120 as shown in Fig. 1.

At block 310, the network device 120 determines information indicating a limited number of downlink control channel candidate and/or a limited number of control channel elements in a time slot. In this way, the balance between flexibility and capability can be achieved.

In some embodiments, the network device 120 may receive information indicating that the terminal device 110-1 supports the low complexity mode. The supported mode may be reported by an arbitrary number or within a predefined set in specification. For example, the network device 129 may receive the information indicating “1” to inform the network device 120 that the terminal device 110-1 may support the low complexity mode.

At block 320, the network device 120 transmits the information indicating the limited number of downlink control channel candidate and/or the limited number of control channel elements in the time slot. For example, the information may be transmitted via radio resource control (RRC) signaling. In some embodiments, the ueCapabilityInformation message may comprise a new domain “maxPdcchCandidates” which indicates the limited number of PDCCH candidates. Alternatively, the ueCapabilityInformation message may comprise another domain “maxPdcchCCE” which indicates the limited number of CCEs. In other embodiments, the limited number of PDCCH candidates and the limited number of CCEs may be indicated by “maxPdcchCandidates” and “maxPdcchCCE” in the UEAssistanceInformation, respectively.

In some embodiments, the terminal device 110-1 may not monitor all of the PDCCH candidates or CCEs. The priority information between the PDCCH candidates may be used. Alternatively, the priority information between the CCEs may also be used. The network device 120 may determine the priority information and transmit the priory information to the terminal device 110-1. For example, the priority information may be transmitted via the RRC signaling. The priority information may be configured based on aggregation level of the PDCCH candidate and/or the CCE. The priority information may indicate that the priority of the aggregation levels may be 2>4>1>8. In this way, it is beneficial for the network device 120 aware downlink control information (DCI) scheduling based on coverage of the terminal device 110-1.

Reference is first made to Fig. 4, which shows a signaling chart illustrating interactions 400 among network devices according to some example embodiments of the present disclosure. Only for the purpose of discussion, the process 400 will be described with reference to Fig. 1. The process 400 may involve the terminal device 110-1 and the network device 120 in Fig. 1.

In some embodiments, the terminal device 110-1 may support different modes. In some embodiments, the terminal device 110-1 may support a normal capability mode. Alternatively, the terminal device 110-1 may support a low complexity mode. Only as an example, in 5G communication systems, there are serval scenarios, for example, enhanced mobile broadband (eMBB) , massive machine-type communication (mMTC) , and Ultra-Reliable and Low Latency communication (URLLC) . In some embodiments, if the terminal device 110-1 is in the scenario of massive machine-type communication, the terminal device 110-1 may need to save power. Thus, the terminal device 110-1 may support the low complexity mode. In some embodiments, the terminal device 110-1 may transmit 4005 information indicating its support mode. The supported mode may be reported by an arbitrary number or within a predefined set in specification. For example, the terminal device 110-1 may transmit the information indicating “1” to inform the network device 120 that the terminal device 110-1 may support the low complexity mode.

The network device may determine 4010 information indicating a limited number of downlink control channel candidate and/or a limited number of control channel elements in a time slot. In this way, the balance between flexibility and capability can be achieved.

The network device 120 may transmit 4015 the information indicating the limited number of downlink control channel candidate and/or the limited number of control channel elements in the time slot. For example, the information may be transmitted via radio resource control (RRC) signaling. In some embodiments, the ueCapabilityInformation message may comprise a new domain “maxPdcchCandidates” which indicates the limited number of PDCCH candidates. Alternatively, the ueCapabilityInformation message may comprise another domain “maxPdcchCCE” which indicates the limited number of CCEs. In other embodiments, the limited number of PDCCH candidates and the limited number of CCEs may be indicated by “maxPdcchCandidates” and “maxPdcchCCE” in the UEAssistanceInformation, respectively.

The terminal device 110-1 determines 4020 the limited number of downlink control channel candidate and/or the limited number of control channel elements in a time slot if the terminal device 110-1 supports the low complexity mode. In some embodiments, the terminal device 110-1 may receive information indicating the limited number of downlink control channel candidate and/or the limited number of CCEs.

In some embodiments, for higher frequency operation, larger sub carrier space (SCS) may be introduced. Tables shown the limited number of PDCCH candidates or CCE can be extended. Such tables may be preconfigured at the terminal device 110-1 and the network device 120. Alternatively, such tables can be transmitted from the network device 120 to the terminal device 110-1.

In some embodiments, the terminal device 110-1 may not monitor all of the PDCCH candidates or CCEs. The priority information between the PDCCH candidates may be used. Alternatively, the priority information between the CCEs may also be used. The network device 120 may determine 4025 the priority information and transmit the priory information to the terminal device 110-1. The priority information may be configured based on aggregation level of the PDCCH candidate and/or the CCE. The priority information may indicate that the priority of the aggregation levels may be 2>4>1>8. In this way, it is beneficial for the network device 120 aware downlink control information (DCI) scheduling based on coverage of the terminal device 110-1.

In some embodiments, score factor can be introduced for different aggregation level (L) , different PDCCH candidate index in aggregation level (k) ) , different USS (j) . In some embodiments, the fewer score represents the higher priority. Alternatively, the more score represents higher priority which is based on the definition of score.

In some embodiments, the score may be obtained based on log2 (L) *A+ k*B + j*C, where A, B, C is RRC configured parameter. When C >= 8*B + 4*A, then USS index has the highest priority, i.e. priority order is based on USS index. When B >= 4*A, then it’s aggregation level first order, i.e. the index 0 for aggregation level 1, 2, 4, 8 candidates first. When A >= 8*B, then it’s index first order, L with the value 1 has higher priority than L with the value 2. When A <= -8*B, then it is index first order, L with the value 1 has lower priority than L with the value 2.

Alternatively, the score may be obtained A (log2 (L) ) + k*B (log2 (L) ) , where A (n) and B (n) is RRC configured parameter per aggregation level. When A (n) = 0 for all L and B (n) = 1/ (M (L) ) , where M (L) is the configured number of candidates for L, then scaling for each L is used. For example, L=1, 2, M (1) = 8, M (2) = 4. The needed candidates is 12, however only 6 candidates left. The score for the 12 candidates is 0, 1/8, 2/8, 3/8, 4/8, 5/8, 6/8, 7/8, 0, 1/4, 2/4, 3/4. The chosen candidates pairs (L, K) are (1, 0) , (1, 1) , (1, 2) , (1, 3) , (2, 0) , (2, 1) which is the scaling of the original candidates. Alternatively, the score may be obtained D (L, k) , where D (L, k) is RRC configured priority for aggregation level L and candidate index k for L. Table 15 shows pseudocodes of scoring.

Table 15

The network device 120 may transmit 4030 the priority information to the terminal device 110-1. For example, the priority information may be transmitted via the RRC signaling.

The terminal device 110-1 monitors 4040 at least one downlink control channel candidate or CCE. In some examples, the terminal device 110-1 may monitor all of the limited number of downlink channel candidates. Alternatively, the terminal device 110-1 may monitor all of the limited number of CCEs.

In some embodiments, the terminal device 110-1 may not monitor all of the PDCCH candidates or CCEs. In such situation, the terminal device 110-1 may select 4035 at least one downlink control channel candidate or CCE for the monitoring 4040 based on the priority information.

The terminal device 110-1 decodes 4045 downlink control information on the monitored downlink channel candidate and/or the CCE. For example, if the terminal device 110-1 monitors all of the limited number of PDCCH candidates and/or CCEs, the terminal device 110-1 may decode the downlink control information on all of the PDCCH candidates and/or CCEs. Alternatively or in addition, the terminal device 110-1 may decode the downlink control information on the downlink channel candidate and/or the CCE monitored based on the priority information.

Fig. 5 is a simplified block diagram of a device 500 that is suitable for implementing embodiments of the present disclosure. The device 500 can be considered as a further example implementation of the terminal device 110 and the network device 120 as shown in Fig. 1. Accordingly, the device 500 can be implemented at or as at least a part of the terminal device 110 or the network device 120.

As shown, the device 500 includes a processor 510, a memory 520 coupled to the processor 510, a suitable transmitter (TX) and receiver (RX) 540 coupled to the processor 510, and a communication interface coupled to the TX/RX 540. The memory 520 stores at least a part of a program 530. The TX/RX 540 is for bidirectional communications. The TX/RX 540 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN) , or Uu interface for communication between the eNB and a terminal device.

The program 530 is assumed to include program instructions that, when executed by the associated processor 510, enable the device 500 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Fig. 2 to 4. The embodiments herein may be implemented by computer software executable by the processor 510 of the device 500, or by hardware, or by a combination of software and hardware. The processor 510 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 510 and memory 520 may form processing means 550 adapted to implement various embodiments of the present disclosure.

The memory 520 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 520 is shown in the device 500, there may be several physically distinct memory modules in the device 500. The processor 510 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to any of Figs. 2-4. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A communication method comprising:

in accordance with a determination that a terminal device supports a low complexity mode, determining, at the terminal device, at least one of: a limited number of downlink control channel candidates in a time slot or a limited number of control channel elements in the time slot;

monitoring at least one downlink control channel candidate or control channel element from the limited number of downlink control channel candidates or the limited number of control channel elements; and

decoding downlink control information on the monitored downlink control channel candidate or the monitored control channel element.
The method of claim 1, wherein determining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements comprises:

receiving information indicating at least one of the limited number of downlink control channel candidates or the limited number of control channel elements via radio resource control, RRC, signaling; and

obtaining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements from the information.
The method of claim 1, wherein determining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements comprises:

determining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements from predetermined configuration.
The method of claim 1, further comprising:

transmitting to a network device information indicating that the terminal device supports the low complexity mode.
The method of claim 1, further comprising:

receiving, from a network device, priority information among the limited number of downlink control channel candidates or the limited number of control channel elements, the priority information associated with aggregation level of the downlink control channel or the control channel element; and

selecting based on the priority information the at least one downlink control channel candidate or control channel element for the monitoring.
The method of claim 1, further comprising:

receiving, from a network device, priority information among the limited number of downlink control channel candidates or the limited number of control channel element, the priority information associated with the low complexity mode; and

selecting based on the priority information the at least one downlink control channel candidate or control channel element for the monitoring for the monitoring.
The method of claim 1, further comprising:

receiving, from a network device, priority information among the limited number of downlink control channel candidates or the limited number of control channel elements, the priority information associated with an index of each aggregation level of the downlink control channel or control channel element; and

selecting based on the priority information the at least one downlink control channel candidate or control channel element for the monitoring.
A communication method comprising:

determining, at a network device, at least one of a limited number of downlink control channel candidates or a limited number of control channel element which is applicable to a terminal device supported a low complexity mode; and

transmitting to a terminal device information indicating at least one of the limited number of downlink control channel candidates or the limited number of control channel elements.
The method of claim 8, further comprising:

receiving from a terminal device information indicating that the terminal device supports the low complexity mode.
The method of claim 8, further comprising:

transmitting to the terminal device priority information among the limited number of downlink control channel candidates or the limited number of control channel elements, the priority information associated with one of: aggregation level of the downlink control channel or the control channel element, the low complexity mode or an index of each aggregation level of the downlink control channel or the control channel element.
A terminal device, comprising:

a processing unit; and

a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the terminal device to perform:

in accordance with a determination that a terminal device supports a low complexity mode, determining, at the terminal device, at least one of: a limited number of downlink control channel candidates in a time slot or a limited number of control channel elements in the time slot;

monitoring at least one downlink control channel candidate or control channel element from the limited number of downlink control channel candidates or the limited number of control channel elements; and

decoding downlink control information on the monitored downlink control channel candidate or the monitored control channel element.
The terminal device of claim 11, wherein determining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements comprises:

receiving information indicating at least one of the limited number of downlink control channel candidates or the limited number of control channel elements via radio resource control, RRC, signaling; and

obtaining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements from the information.
The terminal device of claim 11, wherein determining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements comprises:

determining at least one of the limited number of downlink control channel candidates or the limited number of control channel elements from predetermined configuration.
The terminal device of claim 11, wherein the terminal device is further caused to perform:

transmitting to a network device information indicating that the terminal device supports the low complexity mode.
The terminal device of claim 11, wherein the terminal device is further caused to perform:

receiving, from a network device, priority information among the limited number of downlink control channel candidates or the limited number of control channel elements, the priority information associated with aggregation level of the downlink control channel or the control channel element; and

selecting based on the priority information the at least one downlink control channel candidate or control channel element for the monitoring.
The terminal device of claim 11, wherein the terminal device is further caused to perform:

receiving, from a network device, priority information among the limited number of downlink control channel candidates or the limited number of control channel element, the priority information associated with the low complexity mode; and

selecting based on the priority information the at least one downlink control channel candidate or control channel element for the monitoring for the monitoring.
The terminal device of claim 11, wherein the terminal device is further caused to perform:

receiving, from a network device, priority information among the limited number of downlink control channel candidates or the limited number of control channel elements, the priority information associated with an index of each aggregation level of the downlink control channel or control channel element; and

selecting based on the priority information the at least one downlink control channel candidate or control channel element for the monitoring.
A network device, comprising:

a processing unit; and

a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the network device to perform:

determining, at a network device, at least one of a limited number of downlink control channel candidates or a limited number of control channel element which is applicable to a terminal device supported a low complexity mode; and

transmitting to a terminal device information indicating at least one of the limited numbers of downlink control channel candidates or the limited number of control channel elements.
The network device of claim 18, wherein the terminal device is further caused to perform:

receiving from a terminal device information indicating that the terminal device supports the low complexity mode.
The network device of claim 18, wherein the terminal device is further caused to perform:

transmitting to the terminal device priority information among the limited number of downlink control channel candidates or the limited number of control channel elements, the priority information associated with one of: aggregation level of the downlink control channel or the control channel element, the low complexity mode or an index of each aggregation level of the downlink control channel or the control channel element.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to any of claims 1-7.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to any of claim 8-10.