WO2024020901A1

WO2024020901A1 - Serving cell search

Info

Publication number: WO2024020901A1
Application number: PCT/CN2022/108411
Authority: WO
Inventors: Lars Dalsgaard; Yue Ji CHEN
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2022-07-27
Filing date: 2022-07-27
Publication date: 2024-02-01
Also published as: CN117796033A

Abstract

Embodiments of the present disclosure relate to devices, methods, apparatuses and computer readable storage media of serving cell search. The method comprises determining a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a second frequency range (FR2) in New Radio (NR) and at least one of the following: a Long Tern Evolution (LTE) or a first frequency range (FR1) in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and performing the cell search based on the determined pattern. The approach proposed in the present disclosure may allow User Equipment (UE) time to perform the cell search accounting the maximum configured number of carriers without unnecessarily extending the allowed search time, and therefore unnecessary long UE delay may be avoided.

Description

SERVING CELL SEARCH

FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication and in particular to devices, methods, apparatuses and computer readable storage media of serving cell search.

BACKGROUND

Currently, expected search time for User Equipment (UE) to detect potential cells on a carrier depends on the Radio Access Technology (RAT) and for NR whether the carrier is in Frequency Range 1 (FR1) or Frequency Range 2 (FR2) . In case the UE detects that the serving cell quality no longer fulfil the cell selection criteria, the UE may search configured carriers non-stop and regardless any rule limiting the UE measurement activity.

In Long Term Evolution (LTE) , the cell detection and measurement may be performed periodicity associated with Primary Synchronisation Signal (PSS) , Secondary Synchronisation Signal (SSS) or Common Reference Signal (CRS) , while in NR, the cell detection and measurement may be performed every SSB or SMTC periodicity (in ms) which is network configured.

SUMMARY

In general, example embodiments of the present disclosure provide a solution of serving cell search.

In a first aspect, there is provided a first device. The first device comprises at least one processor; and at least one memory including computer program codes; the at least one memory storing instructions that, when executed by the at least one processor, cause the first device at least to determine a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and perform the cell search based on the determined pattern.

In a second aspect, there is provided a second device. The second device comprises at least one processor; and at least one memory including computer program codes; the at least one memory storing instructions that, when executed by the at least one processor, cause the second device at least to generate an indication of determine a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and transmit the indication to the first device.

In a third aspect, there is provided a method. The method comprises determining a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and performing the cell search based on the determined pattern.

In a fourth aspect, there is provide a method. The method comprises generating an indication of determine a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and transmitting the indication to the first device.

In a fifth aspect, there is provided an apparatus comprising means for determining a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and means for performing the cell search based on the determined pattern.

In a sixth aspect, there is provided an apparatus comprising means for generating an indication of determine a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and means for transmitting the indication to the first device.

In a seventh aspect, there is provided a computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to carry out the method according to the third aspect or the fourth aspect.

Other features and advantages of the embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure are presented in the sense of examples and their advantages are explained in greater detail below, with reference to the accompanying drawings, where

FIG. 1 illustrates an example environment in which example embodiments of the present disclosure can be implemented;

FIG. 2 shows a signaling chart illustrating a process of serving cell search according to some example embodiments of the present disclosure;

FIG. 3 shows a flowchart of an example method of serving cell search according to some example embodiments of the present disclosure;

FIG. 4 shows a flowchart of an example method of serving cell search according to some example embodiments of the present disclosure;

FIG. 5 shows a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

FIG. 6 shows a block diagram of an example computer readable medium in accordance with some 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 limitation 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.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish functionalities of various elements. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. 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. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as fifth generation (5G) systems, Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future fifth generation (5G) new radio (NR) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR Next Generation NodeB (gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. A RAN split architecture comprises a gNB-CU (Centralized unit, hosting RRC, SDAP and PDCP) controlling a plurality of gNB-DUs (Distributed unit, hosting RLC, MAC and PHY) . A relay node may correspond to DU part of the IAB node.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a subscriber station (SS) , a portable subscriber station, a mobile station (MS) , or an access terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to Mobile Termination (MT) part of the integrated access and backhaul (IAB) node (a.k.a. a relay node) . In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

Although functionalities described herein can be performed, in various example embodiments, in a fixed and/or a wireless network node, in other example embodiments, functionalities may be implemented in a user equipment apparatus (such as a cell phone or tablet computer or laptop computer or desktop computer or mobile IoT device or fixed IoT device) . This user equipment apparatus can, for example, be furnished with corresponding capabilities as described in connection with the fixed and/or the wireless network node (s) , as appropriate. The user equipment apparatus may be the user equipment and/or or a control device, such as a chipset or processor, configured to control the user equipment when installed therein. Examples of such functionalities include the bootstrapping server function and/or the home subscriber server, which may be implemented in the user equipment apparatus by providing the user equipment apparatus with software configured to cause the user equipment apparatus to perform from the point of view of these functions/nodes.

FIG. 1 shows an example communication network 100 in which embodiments of the present disclosure can be implemented. As shown in FIG. 1, the communication network 100 may comprise a terminal device 110 (hereinafter may also be referred to as a UE 110 or a first device 110. The communication network 100 may further comprise a network device 120 (hereinafter may also be referred to as a gNB 120 or a second device 120) . The terminal device 110 and the network device 120 may communicate with each other.

It is to be understood that the number of network devices and terminal devices shown in FIG. 1 is given for the purpose of illustration without suggesting any limitations. The communication network 100 may include any suitable number of network devices and terminal devices.

Currently, the UE may measure the Synchronisation Signal-Reference Signal Received Power (SS-RSRP) and Secondary synchronization Signal Reference Signal Received Quality (SS-RSRQ) level of the serving cell and evaluate the cell selection criterion for the serving cell at least once every M1*N1 Discontinuous Reception (DRX) cycle; where M1=2 if SSB measurement timing configuration (SMTC) periodicity (T _SMTC) > 20 ms and DRX cycle ≤ 0.64 second, otherwise M1=1.

The UE may filter the SS-RSRP and SS-RSRQ measurements of the serving cell using at least 2 measurements. Within the set of measurements used for the filtering, at least two measurements may be spaced by, at least DRX cycle/2.

If the UE has evaluated (according to Table 1 as below) in N _serv consecutive DRX cycles that the serving cell does not fulfil the cell selection criterion, the UE may initiate the measurements of all neighbour cells indicated by the serving cell. If the UE in Radio Resource Control (RRC) IDLE mode fails to find any new suitable cell based on searches and measurements using the intra-frequency, inter-frequency and inter-RAT information indicated in the system information for 10s, the UE may initiate cell selection procedures for the selected Public Land Mobile Network (PLMN) .

Table 1: definition of N _serv

However, the conventional mechanism for the cell search may not allow UE reasonable search time for all scenarios. For example, the UE may be configured with one or more NR inter-frequency carriers in FR1 and FR2 to be measured in the idle mode. In this case, a total of up to 14 carriers as minimum including the serving carrier. For NR, the number of layers may be up to 7 and may consist of FR1 and/or FR2 carriers.

Expected search time for the UE to detect potential cells on a carrier depends on the Radio Access Technology (RAT) and for NR whether the carrier is in FR1 or FR2. In case the UE detects that the serving cell quality no longer fulfil the cell selection criteria, the UE may search configured carriers non-stop and regardless any rule limiting the UE measurement activity.

In LTE, the cell detection and measurement may be performed every 5ms due the reference signals being available with 5ms periodicity, for example, associated with PSS, SSS and CRS.

In NR, the cell detection and measurement may be performed every SSB periodicity (in ms) due the reference signals (PSS, SSS) being available with SSB periodicity or assumed being available every SMTC periodicity, where SSB or SMTC periodicity may be configured by the network and have following range: [5, 10, 20, 40, 80 and 160] ms.

To estimate the UE search time when defining an approximate maximum search time needed to search all possible carriers when required (which in this scenario is when the serving cell quality no longer fulfil the cell selection criteria) , the UE time for cell detection and time for measurements on a carrier after a potential cell detection may be estimated and this time may be considered for all possible configured carriers (i.e., up to 14 carriers) .

For LTE, the general assumption is that the UE under the worst required conditions should be able to detect an available cell using 5 instances of PSS/SSS. This then needs to be followed by a round of measurements. That is, up to 5 measurements (to account for worst conditions) may be performed in connected mode while only 2 samples may need for the idle mode.

For NR it is also assumed that up to 5 samples are needed in FR1 followed by a round of measurements (also 5 and 2 samples assumed in connected and idle mode respectively) . For FR2 there is a need for allowing UE time to sweep over a number of Rx panels and spatial settings. Exactly how the UE has implemented the sweep is up to UE implementation. In conventional way, there are two approaches, namely either use connected mode requirements based on no DRX in use or use idle mode performance re-calculated to not being applying DRX but instead based on the configured SMTC periodicity of the carrier being measured.

For example, if the connected mode requirements are considered as baseline, which is assuming that 5 samples of PSS/SSS for cell detection are used and a round of measurement also need 5 samples, search time for 5 instances of PSS/SSS + 5 CRS measurements for the LTE may be equal to 5*5ms + 5*5ms + margin = 100ms (it should be noted that the margin is optional) . In this case, the search time for NR FR1 may be equal to (T _{PSS/SSS_sync_intra} + T _{SSB_measurement_period_intra}) = max (600ms, ceil (5 x K _p) x SMTC period) ^Note 1 x CSSF _intra + max (200ms, ceil (5 x K _p) x SMTC period) ^Note 1 x CSSF _intra=max(600ms, 5 x SMTC period) + max (200ms, 5 x SMTC period) (no DRX in use) =(25ms –800ms) + (25 -800) = [50; 1600ms] , where SMTC= [5, 10, 20, 40, 80 and 160] ms and no margin applied (assuming UE use SMTC of the carrier and not restricted by any rules limiting UE measuring including DRX) .

Furthermore, in this case, the search time for NR FR2 may be equal to (T _{PSS/SSS_sync_intra} + T _{SSB_measurement_period_intra}) = (max (600ms, ceil (M _{pss/sss_sync_w/o_gaps} x K _p x K _{layer1_measurement}) x SMTC period) ^Note 1 x CSSF _intra) + (max (400ms, ceil (M _{meas_period_w/o_gaps} x K _p x K _{layer1_measurement}) x SMTC period) ^Note 1 x CSSF _intra) = (max (600ms, M _{pss/sss_sync_w/o_gaps} x SMTC period) ) + (max (400ms, M _{meas_period_w/o_gaps} x SMTC period) ) = (120 -3840) ms +(120 -3840) ms= 240 –7680ms, where SMTC= [5, 10, 20, 40, 80 and 160] ms and no margin applied (assuming UE use SMTC of the carrier and not restricted by any rules limiting UE measuring including DRX) and M _{pss/sss_sync_w/o_gaps} = M _{meas_period_w/o_gaps} = 24.

That is, in the connected mode, per NR FR1 carrier, a total search and measurements would be 50ms –1600ms, which per NR FR2 carrier, a total search and measurements would be: 240ms –7680ms, due to the requirement ‘regardless any rule limiting the UE measurement activity’.

Furthermore, if the idle mode requirements are considered as baseline, in which X samples for LTE and 36 samples of PSS/SSS for cell detection are needed for NR cell detection and Y samples for LTE and 4 samples for NR are needed for a round of measurement, search time for 5 instances of PSS/SSS + 2 CRS measurements for the LTE may be equal to X*5ms + Y*5ms + margin = 70ms (where addition of margin is optional) . In this case, the search time for NR FR1 may be equal to (T _{PSS/SSS_sync_intra} + T _{SSB_measurement_period_intra}) = 36 x SMTC period + 4 x SMTC period= 200ms –6400ms, while for NR FR2 may be equal to (T _{PSS/SSS_sync_intra} + T _{SSB_measurement_period_intra}) = 36 x 8 x SMTC period + 4 x 8 x SMTC period= 1600ms –51200ms, where it is assumed that a carrier is measured according to the configured SMTC period. Assuming that the UE is allowed to search each carrier in a serial manner, for the worst-case scenario with connected mode assumptions, 7 NR FR2 carriers + 7 LTE carriers (including serving) may need up to 54460ms, while for the worst-case scenario with idle mode assumptions, 7 NR FR2 carriers + 7 LTE carriers (including serving) may need up to 358890ms. Even assuming per FR search, the maximum search time based on UE minimum requirements would be limited by the FR2 search time (53760ms -358400ms) .

That is, with the conventional UE requirement for a cell search, the search time of the UE required for the cell search may exceed the threshold time interval, for example, 10s, when assuming UE minimum requirements.

It is to be understood that in these examples described as above, intra-frequency requirements is assumed to be used as a baseline. However, the solution in the present disclosure is not restricted to be based intra-frequency measurement requirements and could e.g., also be based on inter-frequency measurement requirements or inter-RAT measurement requirements.

Therefore, the present disclosure provides solutions of serving cell search. In this solution, the UE may determine a pattern for cell search. The pattern may indicate the UE to search the carriers associated with LTE and/or FR1 and FR2 in parallel or search the carriers associated with LTE and/or FR1 prior to the carriers associated with FR2. Then the UE may perform the cell search based on the determined pattern.

In this way, the approach proposed in the present disclosure may allow UE time to perform the cell search accounting the maximum configured number of carriers without unnecessarily extending the allowed search time, and therefore unnecessary long UE delay may be avoided.

Principle and implementations of the present disclosure will be described in detail below with reference to FIG. 2, which shows a signaling chart illustrating process 200 of serving cell search according to some example embodiments of the present disclosure. For the purpose of discussion, the process 200 will be described with reference to FIG. 1. The process 200 may involve the UE 110 and the gNB 120.

For example, the process 200 may be implemented in a scenario where the UE 110 is not allowed to assume applying DRX in the idle mode when performing cell search due to serving cell no longer fulfilling the cell selection criterion.

Now the reference is made to FIG. 2. As shown, if the cell search is trigged at UE 110, the UE 110 may determine 210 a pattern for the cell search. As an option, the pattern may indicate the cell search on carriers associated with LTE and/or FR1 and FR2 may be performed in parallel. As another option, the pattern may indicate the cell search on carriers associated with LTE and/or FR1 may be perform prior to the cell search on carriers associated with FR2.

In some example embodiments, the UE 110 may determine the pattern for the cell search autonomously. For example, if the UE 110 in is the situation where the serving cell quality is low, the cell search may be performed on carriers associated with LTE and/or FR1 and FR2 in parallel, or performed on carriers associated with LTE and/or FR1 prior to the cell search on carriers associated with FR2, to ensure fast cell search.

Alternatively or additionally, the gNB 120 may determine which pattern is to be used by the UE 110 to perform the cell search. The gNB 120 may generate an indication of the determined pattern and transmit 205 the pattern to the UE 110.

After the pattern for the cell search is determined, the UE 110 may perform 215 the cell search based on the determined pattern.

Embodiments for the cell search of the UE based on different pattern may be described in detail as below. Assuming that the worst-case scenario and no restriction/assumptions on the how the network may configure the SMTC on the configured carriers and assuming the UE is only required searching 1 carrier at a time. As described above, the overall time can be up to 358400ms with the idle mode assumptions, 53760ms with the connected mode assumptions, where SMTC period of 160ms and 7 FR2 carriers are assumed. Then the LTE search may also be required, which may be up to 7* [70-100] ms in addition which in all accumulate to a significant overall search time.

In general, the overall search may be allowed in the worst case. Specifically, assuming that the UE is configured with X NR carriers of which Y carriers are FR1 carriers, for the connected mode assumptions, the NR search time may be equal to (Y* [1600] ms +(X-Y) * [7680] ms) while the LTE search time may be equal to (14-X) * [70-100] ms. For the idle mode, the search time may be determined in the same way but using different absolute numbers.

In a case where no limitations in UE search and the maximum worst case configuration of 7 NR carriers (FR1 or FR2) and 7 LTE carriers, the UE requirements of the search time may be expressed as search time = Max (10seconds, 700ms + (Y* [1600] ms +(X-Y) * [7680] ms) ) , where X is the number of configured NR carriers of which Y NR carriers are FR1 carriers.

If the actual configured SMTC period of the configured NR carrier may be less relaxed, the allowed search time may be expressed as Search time = Max (10seconds, T _{LTE_carrier_search} + (Y* [10*SMTC period] ms + (X-Y) * [48*SMTC period] ms) ) , where X is the number of configured NR carriers of which Y NR carriers are FR1 carriers and SMTC is the network configured SMTC of each NR carrier to be searched. This is assuming 5 samples for cell detection and 5 samples for measurements for NR FR1 carriers, and assuming 24 samples for cell detection and 24 samples for measurements for NR FR2 carriers.

In normal case, the search time may be expressed as Search time = Max (10seconds, (T _{LTE_carrier_search} + T _{NR_FR1_carrier_search} + T _{NR_FR2_carrier_search}) ) , where T _{LTE_carrier_search} = time allowed for searching LTE carriers, T _{NR_FR1_carrier_search} = Y* [ [10] *SMTC period] ms, T _{NR_FR2_carrier_search} = (X-Y) * [ [48] *SMTC period] ms; and X is the number of configured NR carriers of which Y NR carriers are FR1 carriers and SMTC is the network configured SMTC of each carrier to be searched.

It is to be understood that the numbers/parameters [10] and [48] used herein may be considered as an example, which may depend on the expected UE requirements for search time and the UE requirement for which mode (connected mode/idle mode) is considered as baseline. Any other suitable number may also be adopted.

If the UE 110 perform the cell search on carriers associated with LTE and/or FR1 and FR2 in parallel, as an option, assuming that current minimum requirement time for cell search of a predefined time interval (for example, 10 seconds) is kept unchanged, the search time may be expressed as:

Search time = Max [ (10, Max (10, 1400 + (Y* [ [10] *SMTC period] ms) ) , Max (10,

(X-Y) * [ [48] *SMTC period] ms) ) ]

= Max [10, (T _{LTE_carrier_search} + T _{NR_FR1_carrier_search}) , T _{NR_FR2_carrier_search}) ] (1)

where X is the number of configured NR carriers of which Y NR carriers are FR1 carriers, SMTC is the network configured SMTC of each carrier to be searched, 1400ms is an example of the time assumed allowed for search time for LTE carriers.

As another option, if the fixed time interval (for example, 10 seconds) may be assumed including the search of LTE carriers, which are allowed to be searched when NR cannot be searched due to SMTC restriction (SSB broadcast) , the search time may be expressed as:

Search time = Max [10, Max [10, T _{NR_FR1_carrier_search}] , Max (10, T _{NR_FR2_carrier_search}) ] (2)

It is also possible that the fixed time interval (for example, 10 seconds) may be assumed including the search of LTE carriers and NR FR1 as LTE and NR FR1 carriers may be allowed to be searched within the fixed time interval. In this case, the search time may be expressed as:

Search time = Max [10, T _{NR_FR2_carrier_search}] (3)

It is to be understood that the fixed lower boundary may also be removed in some scenarios.

In some example embodiments, in a case where the UE 110 perform the cell search on carriers associated with LTE and/or FR1 and FR2 in parallel, the cell search may be stopped when a suitable cell is detected by the UE 110. In this case, the lower boundary for the search cell may be removed. The search time may be expressed as:

Search time = Min [ (700 + (Y* [ [10] *SMTC period] ms) ) , ( (X-Y) * [ [48] *SMTC period] ms) ]

= Min [ (T _{LTE_carrier_search} + T _{NR_FR1_carrier_search}) , T _{NR_FR2_carrier_search}] (4)

where X is the number of configured NR carriers of which Y NR carriers are FR1 carriers, SMTC is the network configured SMTC of each carrier to be searched.

As another option, a new maximum search time may be defined based on the SMTC assumption with 20ms on at least 1 carrier per band and 160ms on rest carriers. In this case, the UE 110 may search only search this one carrier per band only. The search time may be expressed as:

Search time = Max [ (700 + (X1* [ [10] *SMTC period] ms) ) , (Y1* [ [48] *SMTC period] ms) ]

= Max [ (T _{LTE_carrier_search} + T _{NR_FR1_carrier_search}) , T _{NR_FR2_carrier_search}] (5)

where X1 is the number of configured NR FR1 carriers, Y1 is the number of configured NR FR2 carriers with SMTC = 20ms per FR2 band, and SMTC is the network configured SMTC of each FR1 and FR2 carrier to be searched and UE search FR2 carriers with SMTC of 20ms for FR2 carriers. Hence, in one example the Ue search all configured LTE and NR FR1 carriers and all NR FR2 carrier with SMTC = 20ms. In one example the UE is only required to search one FR2 carrier per band and this carrier could in one example be limited to a carrier with SMTC = 20ms or the carrier with the shortest SMTC period.

In this case, it is also possible that UE is only allowed additional time for FR2 search if no FR1 candidate is detected.

In a case where the UE 110 perform the cell search on carriers associated with LTE and/or FR1 prior to those associated with the FR2, if the UE 110 measures LTE and NR FR1 configured carriers, the UE 110 may have a predefined time interval (for example, 10s) to perform the cell search. If the UE 110 is configured with NR FR2 carriers, the UE 110 may have additional search time allowed if the time needed for searching NR FR2 carriers exceeds the predefined time interval. In this case, the search time may be expressed as:

Search time = Min [10, Max [ (T _{LTE_carrier_search} + T _{NR_FR1_carrier_search}) ] , T _{NR_FR2_carrier_search}] (6)

As another option, the UE 110 may initially search LTE and/or NR FR1 carriers. If a suitable cell is detected, the UE 110 may stop the cell search. That is, the UE 110 may not search NR FR2 carriers anymore. In this case, the search time may be expressed as:

Search time1 = 10s; or

Search time2 = Search time1 + T _{NR_FR2_carrier_search} (7)

Alternatively, the search time may also be expressed as:

Search time = Max (10s, T _{NR_FR2_carrier_search}) (8)

In this case, if a suitable cell is detected in LTE or NR FR1, the UE 110 may stop further search on configured carriers including the cell search on configured NR FR2 carriers. If suitable LTE/FR1 cell is searched, the search time may equal to the predefined time interval (such as 10s) . If no suitable LTE/FR1 cell is searched, start to search FR2 cells, the search time may be equal to Max (10s, T _{NR_FR2_carrier_search}) .

In some scenarios, it is also possible that only carriers associated with the FR2 are configured. In this case, the UE 110 may be allowed additional extended search time for the cell search. Such extended search time may depend on for example number of FR2 carriers configured, FR2 carriers with SMTC periodicity of 20ms e.g., in each band (or all carriers) , FR2 carriers in each or all band with the smallest SMTC period.

FIG. 3 shows a flowchart of an example method 300 of serving cell search according to some example embodiments of the present disclosure. The method 300 can be implemented at the first device 110 as shown in FIG. 1. For the purpose of discussion, the method 300 will be described with reference to FIG. 1.

At 310, the first device determines a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2.

In some example embodiments, the first device may determine the pattern by the first device autonomously; or determine the pattern based on an indication of the pattern to be used for the cell search received from a second device.

At 320, the first device performs the cell search based on the determined pattern.

In some example embodiments, if the cell search is to be performed in parallel on respective carriers associated with the FR2 and at least one of the following: LTE or the FR1, the first device may perform the cell search within at least one of the following: a predefined time interval, a time interval for searching respective carriers associated with at least one of the following: LTE or the FR1, or a time interval for searching respective carriers associated with the FR2.

In some example embodiments, if the cell search is to be performed in parallel on respective carriers associated with the FR2 and at least one of the following: LTE or the FR1, the first device may stop the cell search at a time when a satisfied cell is detected.

In some example embodiments, if the cell search is to be performed on respective carriers associated with at least one of the following: LTE or the FR1 are searched prior to respective carriers in the FR2, the first device may perform the cell search on respective carriers associated with at least one of the following: LTE or the FR1 within a predefined time interval.

In some example embodiments, if a satisfied cell is detected, the first device may stop the cell search.

In some example embodiments, if no satisfied cell is detected, the first device may perform the cell search on respective carriers associated with the FR2 within a time interval for searching the respective carriers associated with the FR2.

In some example embodiments, if the first device determines that no carrier associated with the LTE and the FR1 is configured, the first device may perform the cell search within a time interval required by the cell search on respective carriers on the FR2.

In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

FIG. 4 shows a flowchart of an example method 400 of serving cell search according to some example embodiments of the present disclosure. The method 400 can be implemented at the second device 120 as shown in FIG. 1. For the purpose of discussion, the method 400 will be described with reference to FIG. 1.

At 410, the second device generate an indication of a pattern to be used for the cell search performed by a first device, the pattern at least indicating that respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR are searched in parallel, or respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2.

At 420, the second device transmits the indication to the first device.

In some example embodiments, an apparatus capable of performing the method 300 (for example, implemented at the UE 110) may comprise means for performing the respective steps of the method 300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for determining a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and means for performing the cell search based on the determined pattern.

In some example embodiments, an apparatus capable of performing the method 400 (for example, implemented at the gNB 120) may comprise means for performing the respective steps of the method 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for generating an indication of determine a pattern for a cell search, the pattern at least indicating that the cell search is to be performed in parallel on respective carriers associated with a FR2 in NR and at least one of the following: a LTE or a FR1 in NR, or the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the FR1 are searched prior to respective carriers in the FR2; and means for transmitting the indication to the first device.

FIG. 5 is a simplified block diagram of a device 500 that is suitable for implementing embodiments of the present disclosure. The device 500 may be provided to implement the communication device, for example the UE 110 and the gNB 120 as shown in FIG. 1. As shown, the device 500 includes one or more processors 510, one or more memories 540 coupled to the processor 510, and one or more communication modules 540 coupled to the processor 510.

The communication module 540 is for bidirectional communications. The communication module 540 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 540 may include at least one antenna.

The processor 510 may be of any type suitable to the local technical network and may include one or more of the following: 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.

The memory 520 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 524, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 522 and other volatile memories that will not last in the power-down duration.

A computer program 530 includes computer executable instructions that are executed by the associated processor 510. The program 530 may be stored in the ROM 520. The processor 510 may perform any suitable actions and processing by loading the program 530 into the RAM 520.

The embodiments of the present disclosure may be implemented by means of the program 530 so that the device 500 may perform any process of the disclosure as discussed with reference to FIGs. 2 to 5. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 530 may be tangibly contained in a computer readable medium which may be included in the device 500 (such as in the memory 520) or other storage devices that are accessible by the device 500. The device 500 may load the program 530 from the computer readable medium to the RAM 522 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. FIG. 6 shows an example of the computer readable medium 600 in form of CD or DVD. The computer readable medium has the program 530 stored thereon.

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 representations, it is to be understood that the block, device, system, technique or method 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

methods

300 and 400 as described above with reference to FIGs. 3-4. 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 device, 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.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, device or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. More specific examples of the computer 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 languages 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 first device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first device at least to:

determine a pattern for a cell search, the pattern at least indicating that:

the cell search is to be performed in parallel on respective carriers associated with a second frequency range in New Radio, NR, and at least one of the following: a Long Term Evolution, LTE, or a first frequency range in NR, or

the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the first frequency range prior to respective carriers in the second frequency range; and

perform the cell search based on the determined pattern.
The first device of claim 1, wherein the first device is caused to determine the pattern by:

determining the pattern by the first device autonomously; or

determining the pattern based on an indication of the pattern to be used for the cell search received from a second device.
The first device of claim 1, wherein the first device is caused to perform the cell search by:

in accordance with a determination that the cell search is to be performed in parallel on respective carriers associated with the second frequency range and at least one of the following: the LTE or the first frequency range, performing the cell search within at least one of the following:

a predefined time interval,

a time interval for searching respective carriers associated with at least one of the following: the LTE or the first frequency range, or

a time interval for searching respective carriers associated with the second frequency range.
The first device of claim 1, wherein the first device is caused to perform the cell search by:

in accordance with a determination that the cell search is to be performed in parallel on respective carriers associated with the second frequency range and at least one of the following: the LTE or the first frequency range, stopping the cell search at a time when a satisfied cell is detected.
The first device of claim 1, wherein the first device is caused to perform the cell search by:

in accordance with a determination that the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the first frequency range prior to respective carriers in the second frequency range, performing the cell search on respective carriers associated with at least one of the following: the LTE or the first frequency range, within a predefined time interval.
The first device of claim 5, wherein the first device is further caused to:

in accordance with a determination that a satisfied cell is detected, stop the cell search.
The first device of claim 5, wherein the first device is further caused to:

in accordance with a determination that no satisfied cell is detected, perform the cell search on respective carriers associated with the second frequency range within a time interval for searching the respective carriers associated with the second frequency range.
The first device of claim 1, wherein the first device is caused to perform the cell search by:

in accordance with a determination that no carrier associated with the LTE and the first frequency range is configured, performing the cell search within a time interval required by the cell search on respective carriers on the second frequency range.
The first device of any of claims 1-8, wherein the first device comprises a terminal device and the second device comprises a network device.
A second device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the second device at least to:

generate an indication of a pattern to be used for a cell search performed by a first device, the pattern at least indicating that:

the cell search is to be performed in parallel on respective carriers associated with a second frequency range in New Radio, NR, and at least one of the following: a Long Term Evolution, LTE, or a first frequency range in NR, or

the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the first frequency range prior to respective carriers in the second frequency range; and

transmit the indication to the first device.
The second device of claim 10, wherein the first device comprises a terminal device and the second device comprises a network device.
A method comprising:

determining, at a first device, a pattern for a cell search, the pattern at least indicating that:

the cell search is to be performed in parallel on respective carriers associated with a second frequency range in New Radio, NR, and at least one of the following: a Long Term Evolution, LTE, or a first frequency range in NR, or

the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the first frequency range prior to respective carriers in the second frequency range; and

performing the cell search based on the determined pattern.
The method of claim 12, wherein determining the pattern comprises:

receiving, from a second device, an indication of the pattern to be used for a cell search; and

determining the pattern based on the indication.
The method of claim 12, wherein performing the cell search comprises:

in accordance with a determination that the cell search is to be performed in parallel on respective carriers associated with the second frequency range and at least one of the following: LTE or the first frequency range, performing the cell search within at least one of the following:

a predefined time interval,

a time interval for searching respective carriers associated with at least one of the following: the LTE or the first frequency range, or

a time interval for searching respective carriers associated with the second frequency range.
The method of claim 12, wherein performing the cell search comprises:

in accordance with a determination that the cell search is to be performed in parallel on respective carriers associated with the second frequency range and at least one of the following: the LTE or the first frequency range, stopping the cell search at a time when a satisfied cell is detected.
The method of claim 12, wherein performing the cell search comprises:

in accordance with a determination that the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the first frequency range prior to respective carriers in the second frequency range, performing the cell search on respective carriers associated with at least one of the following: the LTE or the first frequency range within a predefined time interval.
The method of claim 16, further comprising:

in accordance with a determination that a satisfied cell is detected, stopping the cell search.
The method of claim 16, further comprising:

in accordance with a determination that no satisfied cell is detected, performing the cell search on respective carriers associated with the second frequency range within a time interval for searching the respective carriers associated with the second frequency range.
The method of claim 12, wherein performing the cell search comprises:

in accordance with a determination that no carrier associated with the LTE and the first frequency range is configured, performing the cell search within a time interval required by the cell search on respective carriers on the second frequency range.
The method of any of claims 12-19, wherein the first device comprises a terminal device and the second device comprises a network device.
A method comprising:

generating, at a second device, an indication of a pattern to be used for a cell search performed by a first device, the pattern at least indicating that:

the cell search is to be performed in parallel on respective carriers associated with a second frequency range in New Radio, NR, and at least one of the following: a Long Term Evolution, LTE, or a first frequency range in NR, or

the cell search is to be performed on respective carriers associated with at least one of the following: the LTE or the first frequency range prior to respective carriers in the second frequency range; and

transmitting the indication to the first device.
The method of claim 21, wherein the first device comprises a terminal device and the second device comprises a network device.
An apparatus comprising means for performing at least the method of any of claims 12-20 or the method of any of claims 21-22.
A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method of any of claims 12-20 or the method of any of claims 21-22.