WO2019095325A1

WO2019095325A1 - Method and apparatus for measurement in a wireless communication system

Info

Publication number: WO2019095325A1
Application number: PCT/CN2017/111743
Authority: WO
Inventors: Technologies Oy Nokia; Li Zhang; Lars Dalsgaard
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy
Priority date: 2017-11-17
Filing date: 2017-11-17
Publication date: 2019-05-23
Also published as: WO2019095325A8; CN111406417B; CN111406417A

Abstract

Embodiments of the present disclosure relate to methods, apparatuses and computer program products for measurement in a wireless communication system. A method implemented at a network device comprises: transmitting, to a terminal device, a configuration of measurement gap for performing measurement at the terminal device; configuring, for the terminal device, non-overlapping measurement windows for a plurality of carriers; and indicating the terminal device to measure more than one carriers during one measurement gap occasion. Embodiments of the present disclosure may reduce radio frequency switching time and/or measurement latency.

Description

METHOD AND APPARATUS FOR MEASUREMENT IN A WIRELESS COMMUNICATION SYSTEM

FIELD

The non-limiting and example embodiments of the present disclosure generally relate to a technical field of wireless communication, and specifically to methods, apparatuses and computer program products for measurement in a wireless communication system.

BACKGROUND

In wireless communication systems, a communication device may be required to perform measurement periodically or based on certain events, so as to acquire estimation on quality of a radio link between the communication device and another device, for example, a network device or a terminal device. The estimation on quality of the radio link may facilitate, for example, mobility management, cell (re) selection, radio link (re) selection, and/or carrier (re) configuration of the communication device.

In a wireless communication system operating on a plurality of carriers, in which a base station serves terminal devices within its coverage with more than one carrier or neighboring cells operate with different carriers, a terminal device may be required to conduct multi-carrier measurements. However, how to perform multi-carrier measurements in an efficient way is still an open problem.

SUMMARY

Various embodiments of the present disclosure mainly aim at providing methods, apparatuses and computer program products for improving measurement of a communication device in a wireless communication system. In some embodiments, overhead for measurement is saved. Alternatively or in addition, in some embodiments, latency for obtaining measurement results for multiple carriers is reduced. Other features and advantages of embodiments of the present disclosure will be understood from the following description of various embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the present disclosure.

In a first aspect of the disclosure, there is provided a method implemented at a network device. The method comprises transmitting, to a terminal device, a configuration of measurement gap for performing measurement at the terminal device; configuring, for the terminal device, non-overlapping measurement windows for a plurality of carriers; and indicating the terminal device to measure more than one carriers during one measurement gap occasion. In an embodiment, configuring non-overlapping measurement windows for a plurality of carriers may comprise: configuring non-overlapping measurement windows for the plurality of carriers within one measurement gap occasion. In another embodiment, each of the measurement windows may be specific to one of the plurality of carriers.

In an embodiment, the information transmitted to the terminal device may indicate at least one of: the number of the at least one carrier to be measured during one measurement gap occasion, an index of the at least one carrier to be measured during measurement gap occasion, and frequency of the at least one carrier to be measured during measurement gap occasion.

In another embodiment, the information may indicate a plurality of carriers to be measured during one measurement gap occasion.

In some embodiments, the configuration of measurement gap may include at least one of: a time length of a measurement gap occasion, and a repetition period of the measurement gap occasion.

In still another embodiment, the network device may configure the non-overlapping measurement windows by configuring a time offset for each of the non-overlapping measurement windows.

In a second aspect of the disclosure, there is provided a method implemented at a terminal device. The method comprises: receiving, from a network device, a configuration of measurement gap for performing measurement at the terminal device; receiving, from the network device, a configuration of non-overlapping measurement windows for a plurality of carriers; determining at least one carrier to be measured during one measurement gap occasion; and performing measurement on the at least one carrier based on the received configuration of measurement gap and the received configuration of non-overlapping measurement windows. In an embodiment, a configuration of non-overlapping measurement windows for a plurality of carriers may comprises a configuration of non-overlapping measurement windows for the plurality of carriers within one measurement gap occasion. In another embodiment, each of the measurement windows may be specific to one of the plurality of carriers.

In a third aspect of the disclosure, there is provided a network device. The network device comprises a processing circuitry and a memory and said memory contains instructions executable by said processing circuitry whereby said network device is operative to carry out a method according to the first aspect of the present disclosure.

In a fourth aspect of the disclosure, there is provided a terminal device. The terminal device comprises a processing circuitry and a memory, and said memory contains instructions executable by said processing circuitry whereby said terminal device is operative to carry out a method according to the second aspect of the present disclosure.

In a fifth aspect of the disclosure, there is provided a computer program. The computer program comprises instructions which, when executed by at least one processing circuitry of a network device, causes the network device to carry out a method according to the first aspect of the present disclosure.

In a sixth aspect of the disclosure, there is provided a computer program. The computer program comprises instructions which, when executed by at least one processing circuitry of a terminal device, causes the terminal device to carry out the method according to the second aspect of the present disclosure.

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

In an eighth aspect of the disclosure, there is provided a computer readable medium having computer program stored thereon which, when executed by at least one processor of a terminal device, causes the terminal device to carry out the method according to the second aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings, in which like reference signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and are not necessarily drawn to scale, in which:

FIG. 1 illustrates an example wireless communication network in which embodiments of the present disclosure may be implemented;

FIG. 2 shows examples of synchronization signal and primary broadcast channel block (SSB) compositions and mappings for different subcarrier spacing;

FIG. 3 shows an example for measurement gap;

FIG. 4 shows conventional carrier measurement;

FIG. 5 illustrates an example of multi-carrier measurement according to an embodiment of the present disclosure;

FIG. 6 illustrates a comparison of switching time overhead between a conventional measurement scheme and a measurement scheme according to an embodiment of the present disclosure;

FIG. 7 illustrates a flow chart of a method in a network device according to an embodiment of the present disclosure;

FIG. 8 illustrates a flow chart of a method in a terminal device according to an embodiment of the present disclosure; and

FIG. 9 illustrates a simplified block diagram of an apparatus that may be embodied as/in a network device and an apparatus that may be embodied as/in a terminal device.

DETAILED DESCRIPTION

Hereinafter, the principle and spirit of the present disclosure will be described with reference to illustrative embodiments. It should be understood that all these embodiments are given merely for one skilled in the art to better understand and further practice the present disclosure, but not for limiting the scope of the present disclosure. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. In the interest of clarity, not all features of an actual implementation are described in this specification.

References in the specification 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 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 one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. 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 liming 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.

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 “wireless communication network” refers to a network following any suitable wireless communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , and so on. The “wireless communication network” may also be referred to as a “wireless communication system. ” Furthermore, communications between network devices, between a network device and a terminal device, or between terminal devices in the wireless communication network may be performed according to any suitable communication protocol, including, but not limited to, Global System for Mobile Communications (GSM) , Universal Mobile Telecommunications System (UMTS) , Long Term Evolution (LTE) , New Radio (NR) , wireless local area network (WLAN) standards, such as the IEEE 802.11 standards, and/or any other appropriate wireless communication standard either currently known or to be developed in the future.

As used herein, the term “network device” refers to a node in a wireless 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 NB (also referred to as a 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.

The term “terminal device” refers to any end device that may be capable of wireless communications. 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) and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As yet another example, in an Internet of Things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

As used herein, a downlink (DL) transmission refers to a transmission from a network device to UE, and an uplink (UL) transmission refers to a transmission in an opposite direction.

FIG. 1 illustrates an example wireless communication network 100 in which embodiments of the present disclosure may be implemented. As shown, the wireless communication network 100 may include one or more network devices, for example,

network devices

101 and 111. A network device may be in a form of a base station (BS) , a Node B (NB) , an evolved NB (eNB) , a gNB, a virtual BS, a Base Transceiver Station (BTS) , or a Base Station Subsystem (BSS) , AP and the like.

In this example, network device 101 provides radio connectivity to a set of UEs 102-1, 102-2, and 102-3, which is collectively referred to as “UE (s) 102” , within its coverage, while network device 111 provides radio connectivity to another set of UEs 112-1 and 112-2, which is collectively referred to as “UE (s) 112” . It should be appreciated that in some embodiments, the network device may provide service to less or more UEs.

In some embodiments, a network device may serve UEs within its coverage with a plurality of carriers at different frequencies, and each UE may be configured with one or more carriers for its communication. To facilitate mobility management (for example, handover) , cell (re) selection, radio link (re) selection, and/or carrier (re) configuration, UE may be configured to perform measurement, for example radio resource management (RRM) measurement, for one or more carriers.

Usually, due to hardware limitation, a UE may not be able to communicate on one carrier and at the same time perform measurement on another carrier. Therefore, to avoid unexpected negative impact of measurement on ongoing communication, a network device may reserve a time interval for the UE to perform measurement by configuring a measurement gap for the UE. During the measurement gap, UE switches its radio frequency (RF) chain from current serving carrier to a carrier to be measured, performs measurement for the carrier and switches back to the serving carrier thereafter.

As an example, the measurement for a carrier may be performed based on pilots, reference signals (for example, but not limited to cell-specific reference signals (CRS) , channel state information reference signals (CSI-RS) and demodulation reference signals (DMRS) ) , and/or synchronization signals (for example, primary synchronization signals (PSS) and secondary synchronization signals (SSS) ) .

In the third generation partnership project (3GPP) , radio access network 1 (RAN1) working group is discussing synchronization signal and primary broadcast channel block (SSB) based measurement. in particular, RAN1 has discussed candidate values for SSB based RRM measurement timing configuration (SMTC) window durations, and SMTC windows with 1ms and 5ms lengths have been agreed, while other values are to be decided later.

In addition, 3GPP RAN 4 working group is discussing requirements for SSB based measurements, and has agreed to define inter-frequency measurement with RF retuning, i.e., the inter-frequency measurement is measurement gap assisted.

Fig. 2 shows SSB compositions and mappings for different subcarrier spacing (SCS) as agreed in 3GPP RAN1 (details can be found in 3GPP RAN1 Chairman Notes for RAN1-NR#2 and RAN1#90 meetings) , where L denotes maximum number of SSB transmissions in one SS-Block burst transmission period. It can be seen from FIG. 2 that potential SSB transmission within a 5ms window may be very short, depending on SCS. For example, with a SCS of 240kHz, the maximum number of SSB transmissions is 64 per period, and even if all of the 64 SSBs transmissions are conducted, the SSBs would only be present in the first 2.25ms of the 5ms window. Moreover, in typical deployments, the network may not transmit all the maximum number of SSBs, which means that SSB may be present in an even shorter time interval in practice.

For SSB based measurements, the measurement gap has to overlap with SSB transmissions on the inter-frequency carriers. Since the SSB transmissions may occur in a short time interval per transmission period, the measurement gap cannot be configured very long in time domain.

The actual time duration of the measurement gap available to the UE may be referred to as a measurement gap length (MGL) as shown in FIG. 3, and it mainly consists of measurement time 320 and UE RF switching time 330. The needed measurement time 320 is determined by SMTC window duration, which may vary depending on number of SSBs transmitted by the network per transmission period. The UE RF switching time 330 is used by the UE for switching its RF chain from the serving carrier to a carrier to be measured and switching back to the serving carrier after having performed the measurement, and is assumed to be 0.25ms to 0.5ms for one way switching depending on the frequency range. Sub-6GHz carrier and mmWave may have different RF implementations leading to different switching times. Therefore, a 6ms MGL, comprising 5ms measurement time, 0.5ms for switching UE RF chain from the serving carrier to the carrier to be measured, and 0.5ms for switching back to the serving carrier, is considered as a baseline for inter-frequency measurement.

In Evolved Universal Terrestrial Radio Access Network (E-UTRAN) , the MGL is defined based on synchronization signal design in Long Term Evolution (LTE) and the assumption of asynchronous networks. With such a design, a UE would need a full measurement time per measurement gap per carrier in order to perform measurements on a carrier including detection of new cells. As a result, conventionally, a basic limitation for the measurement gap is that only one carrier is measured in each measurement gap occasion, no matter how long the MGL is. It means that the measurement gaps may not be used very efficiently, since the switching overhead is constant and independent of the length of the MGL.

In 3GPP RAN4, it has been proposed to shorten the MGL when SMTC window is small, so as to obtain an optimization. For example, 3GPP RAN4 has agreed to support a MGL of 3ms so that time resources can be saved in case necessary measurement time is smaller than 5ms, e.g. when SMTC window duration is only lms. An example of the measurement scheme with short MGL is illustrated in FIG. 4. As shown in FIG. 4, one layer (i.e., carrier, C1, C2 or C3) is measured per measurement gap occasion, and a short MGL 410 is used. However, in this example, overall latency of measurements is long. For instance, if assume alms MGL 410 and a 20ms measurement gap repetition period (MGRP) 420, it would take 3 gaps for the UE to measure all three layers (C1-C3) and the overall latency is 60ms.

To solve at least a part of the above problems, methods, apparatuses and computer program products have been proposed in the present disclosure. Generally speaking, according to embodiments of the present disclosure, multi-carrier measurements may be performed within a single measurement gap, in order to make full use of the small measurement gap, thereby improving efficiency of measurement gap usage.

In an embodiment, the network may configure a measurement window, for example a SMTC window, on multiple inter-frequency layers in a way such that the windows on different layers (i.e., carriers) do not overlap with each other in time domain but are still covered/within a measurement gap occasion, for example, within the effective measurement time in a 6ms MGL. In an embodiment, the network may configure UE to measure one or more inter-frequency layers within a single measurement gap. For example, the network device may indicate the number of layers to measure per measurement gap occasion, and/or indicate one or more specific layers to be measured in a measurement gap occasion. In another example, UE may decide which layers to measure within each measurement gap.

In some embodiments, during one measurement gap occasion, UE switches its RF chain from its serving carrier to different inter-frequency layers indicated by the network, and measures these layers (carriers) one by one. That is, UE switches its RF chain to layer 1, measures layer 1, switches the RF chain to the layer 2, measures the layer 1, and so forth, before UE switches back to the serving cell.

An example of a proposed multi-carrier measurement scheme is illustrated in FIG. 5. In this example, in a single measurement gap occasion with a long MGL 510, three

layers

501, 502 and 503 are measured in their corresponding measurement windows which may be, but not limited to, SMTC windows. That is, it would take only one measurement gap to obtain measurements of all the three layers, and if assume same MGRP 520 of 20ms, the total latency is reduced to 20ms.

In addition, in some embodiment, reduction in the UE RF switching time overhead is achieved. FIG. 6 illustrates switching time overhead comparison of a proposed multi-carrier measurement scheme and a conventional scheme. In a conventional baseline measurement scheme, one layer (carrier) is measured per measurement gap occasion, and in this case there is a need for 4 times of RF switching in order to measure two layers, that is, switching (601) from the serving cell to carrier 1, switching (602) from carrier 1 to the serving carrier, switching (603) from the serving carrier to carrier 2, and switching (604) from carrier 2 to the serving carrier. In contrast, in the proposed scheme, measurements for the two carriers are performed within one measurement gap occasion. Therefore, there are only three times of RF switching for measuring two layers, that is, switching (611) from the serving cell to carrier 1, switching (612) from carrier 1 to carrier 2, and switching (613) from carrier 2 to the serving carrier.

The gain in overhead reduction increases with the number of layers measured within one measurement gap occasion. Therefore, with more layers measured within one measurement gap occasion, larger savings can be achieved, making the gap assisted measurements more system efficient. The saving in overhead is not trivial in a NR system with large subcarrier spacing, in which 0.5ms overhead saving means several additional time slots for data communication.

Reference is now made to FIG. 7 which shows a flowchart of a method 700 implemented at a network device, for example, the

network device

101 or 111 in FIG. 1. For ease of discussion, the method 700 will be described below with reference to network device 101 and the communication network 100 illustrated in FIG. 1. However, embodiments of the present disclosure are not limited thereto.

At block 710, the network device 101 transmits to a terminal device, e.g., one of the UE 102 in FIG. 1, a configuration of a measurement gap occasion for a measurement to be performed at the terminal device. For example rather than limitation, the measurement may be performed by the terminal device for one or more of RRM, cell (re) selection, carrier (re) configuration, link (re) selection, and so on.

In some embodiments, the configuration of the measurement gap occasion may include a time length of the measurement gap occasion. For instance, the network device 101 may configure a 3ms or 6ms measurement gap for the terminal device 102. In another embodiment, alternatively or additionally, the configuration of the measurement gap occasion may include a repetition period of the measurement gap occasion. As an example, the network device 101 may configure a 20ms MGRP for the terminal device 102. It is to be understood that any numeral values described herein are merely for illustration, without suggesting any limitations as to the scope of the present disclosure.

In contrast to the conventional measurement solution, at block 720, the network device 101 configures non-overlapping carrier specific measurement windows for a plurality of carriers for the terminal device 102. In an embodiment, the configured non-overlapping carrier specific measurement windows are within a single measurement gap occasion. That is, a plurality of measurement windows (for example, a plurality of SMTCs) are configured within a same measurement gap occasion.

Alternatively or additionally, the configured measurement windows do not overlap in time, and each measurement window is specific to a carrier (also referred to as layer herein) .

Therefore, in some embodiments, the terminal device 102 is enabled to perform measurement for a plurality of carriers within a single measurement gap occasion. In an embodiment, at block 720, the network device 101 may configure a time offset for each of the plurality of non-overlapping measurement windows. The length of each measurement window may be configured, predetermined or left to UE implementation.

Though a plurality of measurement windows are configured, for example, within one measurement gap occasion, the terminal device 102 may not perform a measurement for a corresponding carrier in each of the configured measurement windows. To provide more flexibility, the specific carrier (s) to be measured may be configurable by the network device, or may be determined by the terminal device. Therefore, in an embodiment, at block 730, the network device 101 may indicate the terminal device to measure more than one carrier during one measurement gap occasion. As an example, the network device 101 may transmit, to the terminal device 102, information on a carrier to be measured during one measurement gap occasion. That is, network device 101 indicates, to the terminal device 102, information on one or more carriers to measure by the terminal device 102.

In an embodiment, at block 730, with the transmitted information, the network device 101 may indicate a plurality of carriers to be measured by the terminal device 102 during one measurement gap occasion. In another embodiment, the information transmitted at block 730 may indicate the number (e.g., 2 or 3) of carriers to be measured during one measurement gap occasion. In still another embodiment, alternatively or additionally, the information transmitted may indicate an index and/or a frequency of at least one carrier to be measured during measurement gap occasion.

In an embodiment, the carriers indicated by the network device 101 at block 730 for the terminal device 102 to measure in one measurement gap occasion may include current serving carrier of the terminal device. In another embodiment, the carriers to be measured in one measurement gap occasion may include only neighbor cell carriers.

Alternatively or in addition, in still another embodiment, the carriers to be measured in one measurement gap occasion may include a carrier for a radio access technique (RAT) different from that used by the serving cell of the terminal device. In some embodiments, the carriers to be measured in one measurement gap occasion may include a carrier for D2D communication, and/or local wireless communication including WLAN, WiFi, and the like.

The method 700 enables the terminal device to perform multi-carrier measurements within one measurement gap occasion. As discussed with reference to FIGs 5 and 6, such a method may bring reduction in both in switching time overhead and measurement latency.

Additionally, in a NR system there is a greater need for measurement gap assisted measurements (including measurement for the serving cell) , and any reduction on overhead may lead to gains in system performance. For example, it may enable the serving cell measurement to be performed continuously.

With method 700, the network is also enabled to balance between measurement latency and available data resources. For example, if latency reduction is a target, the network device 101 may configure denser and longer measurement gaps for the terminal device 102, i.e., configure more effective measurement time per layer/carrier, as shown in the FIG. 5. That is, method 700 provides the flexibility for the network to reduce measurement latency per layer at the cost of more measurement gaps. However, with a legacy measurement approach as shown in FIG. 4, only one layer/carrier can be measured per measurement gap, and such a choice/tradeoff is unavailable for the network, unless the terminal device 102 is configured with less layers/carriers to monitor/measure.

FIG. 8 shows a flowchart for an example method 800 implemented at a terminal device, for example, one of the terminal devices 102 and 112. Though for ease of discussion, method 800 will be described below with reference to the terminal device 102 and the communication network 100 illustrated in FIG. 1, it should be appreciated that embodiments of the present disclosure are not limited thereto.

At block 810, terminal device 102 receives, from the network device 101, a configuration of a measurement gap for performing measurement at the terminal device 102. Descriptions, with respect to measurement, measurement gap, measurement gap occasion and its configuration, provided with reference to method 700 also apply here. For example, in an embodiment, the configuration of the measurement gap received at block 810 from the network 101 may indicate a time length of a measurement gap occasion, and/or a repetition period of the measurement gap occasion.

At block 820, terminal device 102 receives, from the network device 101, a configuration of non-overlapping measurement windows for a plurality of carriers. In an embodiment, the non-overlapping measurement windows are within one measurement gap occasion. Alternatively or in addition, each of the measurement windows may be carrier specific. In another example embodiment, the network device 101 may indicate a time offset for each of the plurality of measurement windows. The non-overlapping measurement windows within a single measurement gap occasion enables the terminal device 102 to measure more than one carriers in one measurement gap occasion, thereby reducing time overhead for RF switching, as illustrated in FIG. 6.

At block 830, terminal device 102 determines at least one carrier to be measured during one measurement gap occasion. The at least one carrier may be determined based on received information from the network device 101. In an embodiment, at block 830, the terminal device may receive, from the network device 101, information on at least carrier to measure during one measurement gap occasion and determining the at least one carrier based on the received information.

In some embodiments, the terminal device may determine the at least one carrier based on the received configuration of measurement gap and the received configuration of non-overlapping measurement windows implicitly.

At block 840, terminal device 102 performs measurement on the at least one carrier according to the received configurations.

In some embodiments, the information received at block 830 is same as that transmitted by the network device 101 at block 730 with method 700. For example, the information may indicate a plurality of carriers to be measured during one measurement gap occasion. Alternatively, or in addition, in an embodiment, the information may indicate one or more of: the number of carriers to be measured during one measurement gap occasion, an index of a carrier to be measured during measurement gap occasion, and frequency of a carrier to be measured during measurement gap occasion.

In some embodiments, the terminal device 102 may be configured by the network device 101, or determine by itself, to measure at least one carrier in one measurement gap occasion, and at block 840, the terminal device 102 performs measurement for the at least one carrier one by one within the one measurement gap occasion, and switches its RF chain the serving carrier only after all of the at least one carrier are measured, in order to reducing switching time overhead.

FIG. 9 illustrates a simplified block diagram of an apparatus 900 that may be embodied in/as a network device, for example, the

network device

101 or 111 shown in FIG. 1, or embodied in/as a terminal device, for example, the terminal device 102 or 112 shown in FIG. 1.

As shown by the example of FIG. 9, apparatus 900 comprises a processor 910 which controls operations and functions of apparatus 900. For example, in some embodiments, the processor 910 may implement various operations by means of instructions 930 stored in a memory 920 coupled thereto. The memory 920 may be any suitable type adapted to local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory terminal devices, magnetic memory terminal devices and systems, optical memory terminal devices and systems, fixed memory and removable memory, as non-limiting examples. Though only one memory unit is shown in FIG. 9, a plurality of physically different memory units may exist in apparatus 900.

The processor 910 may be any proper type adapted to local technical environment, 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 apparatus 900 may also comprise a plurality of processors 910.

The processors 910 may also be coupled with a transceiver 940 which enables reception and transmission of information by means of one or more antennae 950 and/or other components. For example, the processor 910 and the memory 920 can operate in cooperation to implement method 800 described with reference to FIG. 8, or method 700 described with reference to FIG. 7. It shall be appreciated that all the features described above with reference to FIG. s 7-8 also apply to apparatus 900, and therefore will not be detailed here.

Various embodiments of the present disclosure may be implemented by a computer program or a computer program product executable by one or more of the processors (for example processor 910 in FIG. 9) , software, firmware, hardware or in a combination thereof.

Although some of the above description is made in the context of a wireless communication system shown in FIG. 1, it should not be construed as limiting the spirit and scope of the present disclosure. The principle and concept of the present disclosure may be more generally applicable to other scenarios.

In addition, the present disclosure also provides carrier containing the computer instructions 930. The carrier may be computer readable storage medium such as a memory containing the computer program or computer program product as mentioned above. The computer-readable media may include, for example, magnetic disks, magnetic tape, optical disks, phase change memory, or an electronic memory terminal device like a random access memory (RAM) , read only memory (ROM) , flash memory devices, CD-ROM, DVD, Blue-ray disc and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment includes not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may include separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses) , firmware (one or more apparatuses) , software (one or more modules) , or combinations thereof. For a firmware or software, implementation may be made through modules (for example, procedures, functions, and so on) that perform the functions described herein.

Example embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatuses. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including hardware, software, firmware, and a combination thereof. For example, in one embodiment, each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations can be implemented by a computer program or a computer program product which includes computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

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 subject matter described herein, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features firom a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. One of ordinary skill in the art will appreciate that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure. The protection sought herein is as set forth in the claims below.

Claims

A method implemented at a network device, comprising:

transmitting, to a terminal device, a configuration of measurement gap for performing measurement at the terminal device;

configuring, for the terminal device, non-overlapping measurement windows for a plurality of carriers; and

indicating the terminal device to measure more than one carriers during one measurement gap occasion.
The method of Claim 1, wherein configuring non-overlapping measurement windows for a plurality of carriers comprises:

configuring non-overlapping measurement windows for the plurality of carriers within one measurement gap occasion.
The method of Claim 1, wherein each of the measurement windows is specific to one of the plurality of carriers.
The method of Claim 1, wherein indicating comprises:

transmitting information to indicate at least one of:

the number of the at least one carrier to be measured during one measurement gap occasion,

an index of the at least one carrier to be measured during measurement gap occasion, and

frequency of the at least one carrier to be measured during measurement gap occasion.
The method of Claim 4, wherein the information indicates a plurality of carriers to be measured during one measurement gap occasion.
The method of any of Claims 1 to 5, wherein the configuration of measurement gap includes at least one of:

a time length of a measurement gap occasion, and

a repetition period of the measurement gap occasion.
The method of any of Claims 1 to 5, wherein configuring non-overlapping measurement windows comprises:

configuring a time offset for each of the non-overlapping measurement windows.
A method implemented at a terminal device, comprising:

receiving, from a network device, a configuration of measurement gap for performing measurement at the terminal device;

receiving, from the network device, a configuration of non-overlapping measurement windows for a plurality of carriers;

determining at least one carrier to be measured during one measurement gap occasion; and

performing measurement on the at least one carrier based on the received configuration of measurement gap and the received configuration of non-overlapping measurement windows.
The method of Claim 8, wherein a configuration of non-overlapping measurement windows for a plurality of carriers comprises:

a configuration of non-overlapping measurement windows for the plurality of carriers within one measurement gap occasion.
The method of Claim 8, wherein each of the measurement windows is specific to one of the plurality of carriers.
The method of Claim 8, wherein determining at least one carrier to be measured during one measurement gap occasion comprises:

receiving, from the network device, information indicating at least one of:

the number of the at least one carrier to be measured during one measurement gap occasion;

an index of the at least one carrier to be measured during measurement gap occasion; and

frequency of the at least one carrier to be measured during measurement gap occasion; and

determining the at least one carrier based on the received information.
The method of Claim 11, wherein the information indicates a plurality of carriers to be measured during one measurement gap occasion.
The method of Claim 8, wherein determining at least one carrier to be measured during one measurement gap occasion comprises:

determining the at least one carrier based on the received configuration of measurement gap and the received configuration of non-overlapping measurement windows.
The method of Claim 8, wherein performing measurement on the at least one carrier comprises:

performing measurement for the at least one carrier one by one within the one measurement gap occasion; and

switching a radio frequency, RF, chain of the terminal device to its serving carrier only after all of the at least one carrier are measured.
The method of any of Claims 8-14, wherein the configuration of measurement gap indicates at least one of:

a time length of a measurement gap occasion; and

a repetition period of the measurement gap occasion.
The method of any of Claims 8-13, wherein a configuration of non-overlapping measurement windows comprises:

a time offset for each of the non-overlapping measurement windows.
A network device, comprising a processing circuitry and a memory, said memory containing instructions executable by said processing circuitry whereby said network device is operative to carry out the method of any of claims 1-7.
A terminal device, comprising a processing circuitry and a memory, said memory containing instructions executable by said processing circuitry whereby said terminal device is operative to carry out the method of any of claims 8-16.
A computer readable medium having a computer program stored thereon which, when executed by at least one processor of a network device, causes the network device to carry out the method of any of claims 1-7.
A computer readable medium having a computer program stored thereon which, when executed by at least one processor of a terminal device, causes the terminal device to carry out the method of any of claims 8-16.