WO2021068111A1

WO2021068111A1 - Enhanced link budget procedure for initial access

Info

Publication number: WO2021068111A1
Application number: PCT/CN2019/109987
Authority: WO
Inventors: Benny Vejlgaard; Srinivasan Selvaganapathy; Chunhai Yao; Rapeepat Ratasuk; Matha DEGHEL
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2019-10-08
Filing date: 2019-10-08
Publication date: 2021-04-15
Also published as: CN114503728A

Abstract

Embodiments of the present disclosure relate to enhanced link budget procedure for initial access. According to embodiments of the present disclosure, the network device transmits configuration of random access channel and the terminal device determines the coverage enhancement and power boosting based on the configuration and measured power. Thus, collision among terminal devices is reduced.

Description

ENHANCED LINK BUDGET PROCEDURE FOR INITIAL ACCESS

FIELD

Embodiments of the present disclosure generally relate to communication techniques, and more particularly, to methods, devices and computer readable medium for enhanced link budget procedure for initial access.

BACKGROUND

With developments of communication systems, new technologies have been proposed. For example, techniques for improving coverage have been proposed. The terminal devices often have limited power. Thus, it is desired to further improve the coverage of the terminal devices.

SUMMARY

Generally, embodiments of the present disclosure relate to a method for enhanced link budget procedure and corresponding devices.

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 and the computer program codes are configured to, with the at least one processor, cause the first device to receive, at a first device and from a second device, a configuration of a random access channel. The configuration at least indicates resources allocated to a plurality of coverage enhancement levels. The first device is also caused to determine a target coverage enhancement level from the plurality of coverage enhancement levels based on measured power of a first signal received from the second device. The first device is further caused to determine a transmission power level based on the measured power. The first device is yet caused to select a subset of resources from a set of resources allocated to the target coverage enhancement level based on the configuration and the transmission power level. The first device is also caused to transmit a preamble for an uplink transmission at the transmission power level using the subset of resources.

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 and the computer program codes are configured to, with the at least one processor, cause the second device to generate a configuration of a random access channel. The configuration at least indicates resources allocated to a plurality of coverage enhancement levels. The second device is also caused to transmit the configuration to a first device. The second device is further caused to receive, from the first device, a preamble for an uplink transmission at a transmission power level using a subset of resources, the subset of resources being determined based on the configuration.

In a third aspect, there is provided a method. The method comprises receiving, at a first device and from a second device, a configuration of a random access channel, the configuration at least indicating resources allocated to a plurality of coverage enhancement levels. The method also comprises determining a target coverage enhancement level from the plurality of coverage enhancement levels based on measured power of a first signal received from the second device. The method further comprises determining a transmission power level based on the measured power. The method yet comprises selecting a subset of resources from a set of resources allocated to the target coverage enhancement level based on the configuration and the transmission power level. The method also comprises transmitting a preamble for an uplink transmission at the transmission power level using the subset of resources.

In a fourth aspect, there is provided a method. The method comprises generating, at a second device, a configuration of a random access channel. The configuration indicates resources allocated to a plurality of coverage enhancement levels. The method also comprises transmitting the configuration to a first device. The method further comprises receiving, from the first device, a preamble for an uplink transmission at a transmission power level using a subset of resources, the subset of resources being determined based on the configuration.

In a fifth aspect, there is provided an apparatus. The apparatus comprises means for receiving, at a first device and from a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels; means for determining a target coverage enhancement level from the plurality of coverage enhancement levels based on measured power of a first signal received from the second device; means for determining a transmission power level based on the measured power; means for selecting a subset of resources from a set of resources allocated to the target coverage enhancement level based on the configuration and the transmission power level; and means for transmitting a preamble for an uplink transmission at the transmission power level using the subset of resources.

In a sixth aspect, there is provided an apparatus. The apparatus comprises means for generating, at a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels; means for transmitting the configuration to a first device; and means for receiving, from the first device, a preamble for an uplink transmission at a transmission power level using a subset of resources, the subset of resources being determined based on the configuration.

In a seventh aspect, there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the above third or fourth aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

Fig. 1 illustrates a schematic diagram of a communication system according to according to embodiments of the present disclosure;

Fig. 2 illustrates a schematic diagram of interactions between devices according to according to embodiments of the present disclosure;

Fig. 3 illustrates schematic diagrams of gap configurations according to embodiments of the present disclosure;

Fig. 4 illustrates a flow chart of a method according to embodiments of the present disclosure;

Fig. 5 illustrates a flow chart of a method according to embodiments of the present disclosure;

Fig. 6 illustrates a simplified block diagram of an apparatus that is suitable for implementing embodiments of the present disclosure; and

Fig. 7 illustrates a block diagram of an example computer readable medium in accordance with some example 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 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 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 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) , New Radio (NR) 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, 2.65G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future fifth generation (5G) 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 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 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 (loT) 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. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As mentioned above, how to improve the coverage of the terminal devices needs to be further studied. The key enablement to allow better link budget for the fifth generation (5G) new radio (NR) by increasing the transmit power of the terminal device is to use the uplink multi-input-multi-output (MIMO) capability for both transmitting power increase and uplink diversity enhancements. The transmitting signal to be transmitted with be the same data for all transmitting paths. Each transmitting path may use the MIMO pre-coding to enable independent reception at the network devices. Each of the transmitting path may transmit with up to 24 dBm resulting in a total radiated power of 27 dBm for two transmitting paths and 30 dBm for 4 transmitting paths. To compensate for the increased transmitting power and thus increased link budget, the transmissions use a lower duty cycle to minimize the total transmitted power. This means in practice that the transmitting power (and link budget) may be better for shorter periods and zero power for the other time periods.

Generally, the terminal devices are limited to 24 dBm transmit power due to specific absorption rate (SAR) regulatory specifications. The network device is not limited by SAR and typically uses a much higher transmit power in downlink. Therefore, the uplink connection is typically the limited link due to the uplink power restrictions.

Internet of things (IoT) use cases are generally uplink-centric and require significant link budget to enable low power wide area connectivity. For 5G NR to support the same use cases and be competitive compared to NB-IoT an even better link budget is required.

Other use cases supported by 5G NR may also benefit from enhanced link budget, for example, voice services. The problem is that critical voice services can be limited by the 5G NR link budget and not providing enough coverage. Enabling link budget enhancements for IoT, voice, and other low data rate services may provide a more competitive solution for 5G NR.

Specifically, the link budget during initial access for the terminal device may be limited at the cell edge.

Coverage enhancements or link budget enhancements have been studied and included in long term evolution (LTE) for the narrow band (NB) IoT solution. NB-IoT mainly uses narrowband transmission and repetition to enhance the uplink link budget. The 2G solution allows up to 33 dBm transmit power. The NB-IoT solution with repetition or enhanced coding requires significant delay in the transmission and is not suitable for voice or delay sensitive services.

The GSM solution with high transmission power (33 dBm) and duty cycle transmission is not an interesting solution as the terminal device power amplified (PA) is very expensive and power consuming. The standard PA in a 5G NR device is 24 dBm and any output power beyond 24 dBm is not currently supported from a device implementation point of view.

According to embodiments of the present disclosure, the network device transmits configuration of random access channel and the terminal device determines the coverage enhancement and power boosting based on the configuration and measured received power. Thus, collision among terminal devices is reduced.

Fig. 1 illustrates a schematic diagram of a communication system in which embodiments of the present disclosure can be implemented. The communication system 100, which is a part of a communication network, comprises a device 110-1, a device 110-2, ...., a device 110-N, which can be collectively referred to as “device (s) 110. ” The communication system 100 further comprises a device 120. One or more devices are associated with and covered by a cell. It is to be understood that the number of devices and cells shown in Fig. 1 is given for the purpose of illustration without suggesting any limitations. The communication system 100 may comprise any suitable number of devices and cells. In the communication system 100, the device 110 and the device 120 can communicate data and control information to each other. In the case that the device 110 is the terminal device and the device 120 is the network device, a link from the device 120 to the device 110 is referred to as a downlink (DL) , while a link from the device 110 to the device 120 is referred to as an uplink (UL) . The number of devices shown in Fig. 1 is given for the purpose of illustration without suggesting any limitations.

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

Fig. 2 illustrates a schematic diagram of interactions 200 among devices in accordance with embodiments of the present disclosure. The interactions 200 may be implemented at any suitable devices. Only for the purpose of illustrations, the interactions 200 are described to be implemented at the terminal device 110-1 and the network device 120.

The network device 120 generates 2005 a configuration of random access channel (RACH) . The configuration indicates resources allocated to different coverage enhancement levels (CELs) . For example, the resources may be frequency-domain resources. The resources may also be time-domain resources. Alternatively or in addition, the resources may comprise one or more preamble indices. The term “coverage enhancement” used herein refers to an enhanced coverage functionality which can be used by a terminal device that satisfies certain criteria (e.g. received power below a threshold) to access a cell. This is a radio access network (RAN) feature based on repetitions of messages or transmissions between the terminal device and the network device. A single transport block is transmitted over multiple subframes, thereby providing higher transmit energy per information bit for a given transmit power. Coverage enhancement needs may be a function of or may be associated with a particular device's radio link conditions. A wireless system may implement CE techniques to improve the likelihood of successful communications with wireless devices. In some cases, a wireless system may support different CE levels (also referred to as coverage extensions) , each of which may provide a different amount of CE.

There may be one or more transmission power levels in one CEL. The transmission power levels may comprise a power level for normal transmission. The transmission power may also comprise a power level for power-boosted transmission (e.g. power level beyond the normal maximum output power) . The configuration may indicate different subsets of resources allocated to different transmission power levels. The network device 120 may reserve a subset of resources in the set of resources for power-boosted transmission. For example, the network device 120 may reserve a first resource subset (e.g. time-frequency or preamble resource) for normal transmission, a second resource subset for power boosting of 0-2 dB, and a third resource subset for power boosting of 2-4 dB.

The network device 120 transmits 2010 the configuration to the terminal device 110-1. The configuration may be transmitted in system information. The configuration may also comprise information about the number of antenna for power boost initial access. Alternatively or in addition, the configuration may comprise information about selection of power boost offset.

The terminal device 110-1 may measure 2015 power of a signal received from the network device 120. For example, the terminal device 110-1 may measure reference signal received power (RSRP) . The terminal device 110-1 determines 2020 the CEL based on the measured power. The terminal device 110-1 determines 2025 the transmission power level based on the measured power. For example, if the measured power indicates that power boosting is not required, the terminal device 110-1 may determine the power level for normal transmission. Alternatively or in addition, the terminal device 110-1 may determine the power level for power boosting.

The terminal device 110-1 selects 2030 the subset resources based on the transmission power level and the configuration. For example, if the transmission power level is for power boost, the terminal device 110-1 may select the resources assigned for power-boosted transmission within the set of resources. For example, if the transmission power level is for the normal transmission, the terminal device 110-1 may select the first resource subset for normal transmission. If the transmission power level is for the power boosting of 0-2 dB, the terminal device 110-1 may select the second resource subset. If the transmission power level is for the power boosting of 2-4 dB, the terminal device 110-1 may select the third resource subset. In this way, suitable transmission power can be selected.

The terminal device 110-1 transmits 2035 the preamble for the uplink transmission at the transmission power level using the subset of resources. For example, the terminal device 110-1 may transmit a Message 1 in the four-step RACH procedure. In other embodiments, the terminal device may transmit a Message A in the two-step RACH procedure. If the transmission power level is for the normal transmission, the terminal device 110-1 may transmit a normal preamble. If the power boosting is needed, the terminal device 110-1 may transmit a preamble for the power boosting.

The network device 120 may determine 2037 the transmission power level based on the preamble. For example, if the preamble is for the power boosting, the network device 120 may determine that the transmission power level is the power boosting level.

The network device 120 may determine 2040 a gap between a set of transmission repetitions on the uplink shared channel. The gap can be between every N/2 repetitions or every N/4 repetitions depending on network configuration. In some embodiments, the network device 120 may determine the gap for power boosted transmission to ensure that duty cycle restriction (i.e. the fraction of time the device is allowed to transmit at a particular power level) is maintained during the random access. In this case, multiple starting transmission points can be defined to minimize the collision between terminal devices with power boosted transmission. As shown in Fig. 3, the network device 120 may determine the gaps 3010-1, 3010-2 and 3010-3 and the gaps 3030-1, 3030-2 and 3030-3. In this way, the overall power requirement can be maintained. In case if the preamble transmission needs to be repeated multiple times, for power boosting transmission the repetitions need to be scheduled with some gaps to maintain the duty-cycle restriction required to maintain the overall average transmission power over duration within limit. This requires the power boosting transmission to have gaps in between. These gaps and also the starting offset for different power boosted (PB) preamble transmissions can be configured. The start-offset configuration allows multiplexing of different PB transmissions with reduced collision.

The network device 120 may determine 2045 the number of repetitions based on the received preamble. In some embodiments, the network device 120 may adjust the repetitions for physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH) associated with transmission based on received CEL. For example, if the network device 120 receives the preamble for power boosting, the downlink repetition needs to be higher than the number of repetitions the network device 120 uses for the normal coverage.

In some embodiments, in the situation of the four-step RACH procedure, the network device 120 may decide to apply the power boosting for Message3 transmission. In such case, the Message3 transmission should start specific set of subframes from the RACH transmission to maintain the duty cycle restriction. The network device 120 may determine 2047 the duty-cycle offset. As shown in Fig. 3, the network device 120 may determine the offset 3050 for the terminal device 110-1 and the zero offset for the terminal device 110-2. In this way, the collision between terminal devices can be reduced.

The network device 120 may transmit 2050 the response to the terminal device 110-1. In some embodiments, the response may indicate whether the power boosting is applicable to the uplink transmission. The response may comprise one or more of a start offset for transmission on the uplink shared channel, a target transmission power level on the uplink shared channel, or a duty-cycle offset for transmission on the uplink shared channel. The response (for example, Message2) may indicate the power boosting to be applied for the uplink grant for Message3 and also whether the terminal device 110-1 should apply duty-cycle offset or not via a single bit in the scheduling grant. In case if the random access response (RAR) is scheduled after sufficient delay after receiving the power-boosted preamble, the additional duty-cycle restriction for Message3 is not required. The network device 120 may include this additional indication. In the situation of the two-step RACH procedure, the response may be Message B.

In some embodiments, if the terminal device 110-1 selects the normal power transmission and if the RACH Access fails after a number of times, the terminal device 110-1 may first attempt power boosted transmission within the same CEL before attempting the RACH access from next CEL which may require increased number of repetitions corresponds to next CEL. For example, if the terminal device 110-1 cannot receive the response to the preamble, the terminal device 110-1 may determine 2055 the further transmission power level which is higher than the transmission power level. The terminal device 110-1 may transmit 2060 a further preamble at the further transmission power level. If the terminal device 110-1 still cannot receive the further response to the further preamble, the terminal device 110-1 may determine 2065 the further CEL for transmitting the preamble.

Fig. 4 illustrates a flow chart of method 400 according to embodiments of the present disclosure. The method 400 can be implemented at any suitable devices. For example, the method may be implemented at the terminal device 110.

At block 410, the terminal device 110-1 receives the configuration of the random access channel. The configuration indicates resources allocated to different coverage enhancement levels (CELs) . For example, the resources may be frequency-domain resources. The resources may also be time-domain resources. Alternatively or in addition, the resources may comprise one or more preamble indices. The configuration may indicate different subsets of resources allocated to different transmission power levels.

The configuration may be transmitted in system information. The configuration may also comprise information about the number of antenna for power boost initial access. Alternatively or in addition, the configuration may comprise information about selection of power boost offset.

At block 420, the terminal device 110-1 determines the CEL based on the measured power. The terminal device 110-1 may measure 2015 power of a signal received from the network device 120. For example, the terminal device 110-1 may measure reference signal received power (RSRP) .

At block 430, the terminal device 110-1 determines the transmission power level based on the measured power. For example, if the measured power indicates that power boosting is not required, the terminal device 110-1 may determine the power level for normal transmission. Alternatively or in addition, the terminal device 110-1 may determine the power level for power boosting.

At block 440, the terminal device 110-1 selects the subset resources based on the transmission power level and the configuration. For example, if the transmission power level is for power boost, the terminal device 110-1 may select the resources assigned for power-boosted transmission within the set of resources. For example, if the transmission power level is for the normal transmission, the terminal device 110-1 may select the first resource subset for normal transmission. If the transmission power level is for the power boosting of 0-2 dB, the terminal device 110-1 may select the second resource subset. If the transmission power level is for the power boosting of 2-4 dB, the terminal device 110-1 may select the third resource subset.

At block 450, the terminal device 110-1 transmits the preamble to for the uplink transmission at the transmission power level using the subset of resources. The preamble may be Message 1 or Message A. For example, the terminal device 110-1 may transmit Message 1 in the four-step RACH procedure. In other embodiments, the terminal device 110-1 may transmit Message A in the two-step RACH procedure. If the transmission power level is for the normal transmission, the terminal device 110-1 may transmit a normal preamble. If the power boosting is needed, the terminal device 110-1 may transmit a preamble for the power boosting.

In some embodiments, the terminal device 110-1 may compare the transmission power level with a threshold level. If the transmission power level exceeds the threshold level, the terminal device 110-1 may select, based on the configuration, a preamble reserved for the transmission power level and transmit the preamble.

If the terminal device 110-1 detects a failure in receiving a response to the preamble from the second device, the terminal device 110-1 may determine the further transmission power level which is higher than the transmission power level. The terminal device 110-1 may transmit a further preamble at the further transmission power level. If the terminal device 110-1 still cannot receive the further response to the further preamble, the terminal device 110-1 may determine the further CEL for transmitting the preamble.

In some embodiments, the terminal device 110-1 may receive information indicating a gap between a set of repetition transmissions on an uplink shared channel. The terminal device 110-1 may perform the repetition transmissions on the random access channel based on the gap.

The terminal device 110-1 may receive a response to the preamble from the network device 120 and perform further transmissions on the uplink shared channel based on the response. In some embodiments, the response may indicate whether the uplink transmission can be sent with higher transmission power. If the response indicates that the uplink transmission can be sent with the higher transmission power, the response may also comprise the gaps for the same along with the offset to start the uplink transmission. In some embodiments, the response comprises at least one of: a start offset for transmission on the uplink shared channel, a target transmission power level on the uplink shared channel, a duty-cycle offset for transmission on the uplink shared channel, and/or a gap between a set of repetition transmissions on the uplink shared channel.

Fig. 5 illustrates a flow chart of method 500. The method 500 can be implemented at any suitable devices. For example, the method may be implemented at the network device 120.

At block 510, the network device 120 generates a configuration of random access channel (RACH) . The configuration indicates resources allocated to different coverage enhancement levels (CELs) . For example, the resources may be frequency-domain resources. The resources may also be time-domain resources. Alternatively or in addition, the resources may comprise preambles.

There may be one or more transmission power levels in one CEL. The transmission power levels may comprise a power level for normal transmission. The transmission power may also comprise a power level for power-boosted transmission. The configuration may indicate different subsets of resources allocated to different transmission power levels. The network device 120 may reserve a subset of resources in the set of resources for power-boosted transmission. For example, the network device 120 may reserve a first resource subset for normal transmission, a second resource subset for power boosting of 0-2 dB, and a third resource subset for power boosting of 2-4 dB.

At block 520, the network device 120 transmits the configuration to the terminal device 110-1. The configuration may be transmitted in system information. The configuration may also comprise information about the number of antenna for power boost initial access. Alternatively or in addition, the configuration may comprise information about selection of power boost offset.

At block 530, the network device 120 receives the preamble for the uplink transmission at the transmission power level using the subset of resources. The network device 120 may determine the transmission power level based on the preamble. For example, if the preamble is for the power boosting, the network device 120 may determines that the transmission power level is the power boosting level.

In some embodiments, the network device 120 may determine a gap between a set of repetition transmissions on an uplink shared channel. In some embodiments, the network device 120 may determine the gap for power boosted transmission to ensure that duty cycle restriction is maintained during the random access. In this case, multiple starting transmission points can be defined to minimize the collision between terminal devices with power boosted transmission.

The network device 120 may determine the number of repetitions based on the received preamble. In some embodiments, the network device 120 may adjust the repetitions for physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH) associated with transmission based on received CEL. For example, if the network device 120 receives the preamble for power boosting, the downlink repetition needs to be higher than the number of repetitions the network device 120 uses for the CEL.

The network device 120 may transmit the response to the terminal device 110-1. The response may comprise one or more of a start offset for transmission on the uplink shared channel, a target transmission power level on the uplink shared channel, or a duty-cycle offset for transmission on the uplink shared channel. In the situation of the four-step RACH procedure, the response (for example, Message 2) may indicate the power boosting to be applied for the uplink grant for Message 3 and also whether the terminal device 110-1 should apply duty-cycle offset or not via a single bit in the scheduling grant. In case if the RAR is scheduled after sufficient delay after receiving the power-boosted preamble, the additional duty-cycle restriction for Message3 is not required. The network device 120 may include this additional indication. In the situation of the two-step RACH procedure, the response may be Message B.

In some embodiments, an apparatus for performing the method 400 (for example, the terminal device 110) may comprise respective means for performing the corresponding steps in the method 400. These means may be implemented in any suitable manners. For example, it can be implemented by circuitry or software modules.

In some embodiments, the apparatus comprises means for receiving, at a first device and from a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels; means for determining a target coverage enhancement level from the plurality of coverage enhancement levels based on measured power of a first signal received from the second device; means for determining a transmission power level based on the measured power; means for selecting a subset of resources from a set of resources allocated to the target coverage enhancement level based on the configuration and the transmission power level; and means for transmitting a preamble for an uplink transmission at the transmission power level using the subset of resources.

In some embodiments, the means for transmitting the preamble comprises: means for comparing the transmission power level with a threshold level; means for in accordance with a determination that the transmission power level exceeds the threshold level, selecting, based on the configuration, the preamble reserved for the transmission power level; means for transmitting the preamble.

In some embodiments, the apparatus comprises means for in response to detecting a failure in receiving a response to the preamble from the second device, selecting a further transmission power level higher than the transmission power level; means for selecting a further subset of resources based on the further transmission power level and the configuration; and means for transmitting a further preamble at the further transmission power level with the further subset of resources.

In some embodiments, the apparatus comprises means for in response to detecting a failure in receiving a further response to the further preamble from the second device, selecting a further enhancement level from the plurality of coverage enhancement levels.

In some embodiments, the apparatus comprises means for receiving, from the second device, information indicating a gap between a set of repetition transmissions on an uplink shared channel; and means for performing the repetition transmissions on the uplink shared channel based on the gap.

In some embodiments, the apparatus comprises means for receiving a response to the preamble from the second device, the response indicating whether power boosting is applicable to the uplink transmission; and means for transmitting a second signal on an uplink shard channel based on the response.

In some embodiments, wherein if the power boosting is applicable to the uplink transmission, the response comprises at least one of: a start offset for transmission on the uplink shared channel access channel, a target transmission power level on the uplink shared channel, a duty-cycle offset for transmission on the uplink shared channel, and/or a gap between a set of repetition transmissions on the uplink shared channel.

In some embodiments, the resources comprise at least one of: time-domain resources, frequency-domain resources and/or a preamble index.

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

In embodiments, an apparatus for performing the method 500 (for example, the network device 120) may comprise respective means for performing the corresponding steps in the method 500. These means may be implemented in any suitable manners. For example, it can be implemented by circuitry or software modules.

In some embodiments, the apparatus comprises means for generating, at a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels; means for transmitting the configuration to a first device; and means for receiving, from the first device, a preamble for an uplink transmission at a transmission power level with a subset of resources, the subset of resources being determined based on the configuration.

In some embodiments, the means for receiving the preamble comprises: means for in accordance with a determination that the preamble is reserved for the transmission power level, determining that the transmission power level exceeds a threshold level.

In some embodiments, the apparatus comprises means for generating information indicating a gap between a set of repetition transmissions on an uplink shared channel; and means for transmitting the information to the first device.

In some embodiments, the apparatus comprises means for generating a response to the preamble based on the transmission power level, the response indicating whether power boosting is applicable to the uplink transmission; and means for transmitting the response to the first device.

Fig. 6 is a simplified block diagram of a device 600 that is suitable for implementing embodiments of the present disclosure. The device 600 may be provided to implement the communication device, for example the terminal device 110, or the network device 120 as shown in Fig. 1. As shown, the device 600 includes one or more processors 610, one or more memories 620 coupled to the processor 610, and one or more communication modules 640 coupled to the processor 610.

The communication module 640 is for bidirectional communications. The communication module 640 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 610 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 600 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 620 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) 624, 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) 622 and other volatile memories that will not last in the power-down duration.

A computer program 630 includes computer executable instructions that are executed by the associated processor 610. The program 630 may be stored in the ROM 624. The processor 610 may perform any suitable actions and processing by loading the program 630 into the RAM 622.

The embodiments of the present disclosure may be implemented by means of the program 620 so that the device 600 may perform any process of the disclosure as discussed with reference to Figs. 2 and 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 630 may be tangibly contained in a computer readable medium which may be included in the device 600 (such as in the memory 620) or other storage devices that are accessible by the device 600. The device 600 may load the program 630 from the computer readable medium to the RAM 622 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. 7 shows an example of the computer readable medium 700 in form of CD or DVD. The computer readable medium has the program 630 stored thereon.

It should be appreciated that future networks may utilize network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications, this may mean node operations to be carried out, at least partly, in a central/centralized unit, CU, (e.g. server, host or node) operationally coupled to distributed unit, DU, (e.g. a radio head/node) . It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labor between core network operations and base station operations may vary depending on implementation.

In an embodiment, the server may generate a virtual network through which the server communicates with the distributed unit. In general, virtual networking may involve a process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Such virtual network may provide flexible distribution of operations between the server and the radio head/node. In practice, any digital signal processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may be selected according to implementation.

Therefore, in an embodiment, a CU-DU architecture is implemented. In such case the device 600 may be comprised in a central unit (e.g. a control unit, an edge cloud server, a server) operatively coupled (e.g. via a wireless or wired network) to a distributed unit (e.g. a remote radio head/node) . That is, the central unit (e.g. an edge cloud server) and the distributed unit may be stand-alone apparatuses communicating with each other via a radio path or via a wired connection. Alternatively, they may be in a same entity communicating via a wired connection, etc. The edge cloud or edge cloud server may serve a plurality of distributed units or a radio access networks. In an embodiment, at least some of the described processes may be performed by the central unit. In another embodiment, the device 600 may be instead comprised in the distributed unit, and at least some of the described processes may be performed by the distributed unit.

In an embodiment, the execution of at least some of the functionalities of the device 600 may be shared between two physically separate devices (DU and CU) forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes. In an embodiment, such CU-DU architecture may provide flexible distribution of operations between the CU and the DU. In practice, any digital signal processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may be selected according to implementation. In an embodiment, the device 600 controls the execution of the processes, regardless of the location of the apparatus and regardless of where the processes/functions are carried out.

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, apparatus, 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 400-600 as described above with reference to Figs. 3-6. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

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

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, apparatus 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, apparatus, 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 including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the first device to:

receive, from a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels;

determine a target coverage enhancement level from the plurality of coverage enhancement levels based on measured power of a first signal received from the second device;

determine a transmission power level based on the measured power;

select a subset of resources from a set of resources allocated to the target coverage enhancement level based on the configuration and the transmission power level; and

transmit a preamble for an uplink transmission at the transmission power level using the subset of resources.
The first device of claim 1, wherein the first device is caused to transmit the preamble by:

comparing the transmission power level with a threshold level;

in accordance with a determination that the transmission power level exceeds the threshold level, selecting, based on the configuration, the preamble reserved for the transmission power level; and

transmitting the preamble.
The first device of claim 1, wherein the first device is further caused to:

in response to detecting a failure in receiving a response to the preamble from the second device, select a further transmission power level higher than the transmission power level;

select a further subset of resources based on the further transmission power level and the configuration; and

transmit a further preamble at the further transmission power level with the further subset of resources.
The first device of claim 3, wherein the first device is further caused to:

in response to detecting a failure in receiving a further response to the further preamble from the second device, select a further enhancement level from the plurality of coverage enhancement levels.
The first device of claim 1, wherein the first device is further caused to:

receive, from the second device, information indicating a gap between a set of repetition transmissions on an uplink shared channel; and

perform the repetition transmissions on the uplink shared channel based on the gap.
The first device of claim 1, wherein the first device is further caused to:

receive a response to the preamble from the second device, the response indicating whether power boosting is applicable to the uplink transmission; and

transmit a second signal on an uplink shard channel based on the response.
The first device of claim 6, wherein if the power boosting is applicable to the uplink transmission, the response comprises at least one of:

a start offset for transmission on the uplink shared channel access channel,

a target transmission power level on the uplink shared channel,

a duty-cycle offset for transmission on the uplink shared channel, and/or

a gap between a set of repetition transmissions on the uplink shared channel.
The first device of claim 1, wherein the resources comprise at least one of: time-domain resources, frequency-domain resources and/or a preamble index.
The first device of claim 1, 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 including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the second device to:

generate a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels;

transmit the configuration to a first device; and

receive, from the first device, a preamble for an uplink transmission at a transmission power level using a subset of resources, the subset of resources being determined based on the configuration.
The second device of claim 10, wherein the second device is caused to receive the preamble by:

in accordance with a determination that the preamble is reserved for the transmission power level, determining that the transmission power level exceeds a threshold level.
The second device of claim 10, wherein the second device is further caused to:

generate information indicating a gap between two repetition transmissions on the random access channel; and

transmit the information to the first device.
The second device of claim 10, wherein the second device is further caused to:

generate a response to the preamble based on the transmission power level, the response indicating whether power boosting is applicable to the uplink transmission; and

transmit the response to the first device.
The second device of claim 13, wherein if the power boosting is applicable to the uplink transmission, the response comprises at least one of:

a start offset for transmission on the uplink shared channel access channel,

a target transmission power level on the uplink shared channel,

a duty-cycle offset for transmission on the uplink shared channel, and/or

a gap between a set of repetition transmissions on the uplink shared channel.
The second device of claim 10, wherein the resource comprises at least one of: time-domain resources, frequency-domain resources and/or a preamble index.
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:

receiving, at a first device and from a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels;

determining a target coverage enhancement level from the plurality of coverage enhancement levels based on measured power of a first signal received from the second device;

determining a transmission power level based on the measured power;

selecting a subset of resources from a set of resources allocated to the target coverage enhancement level based on the configuration and the transmission power level; and

transmitting a preamble for an uplink transmission at the transmission power level using the subset of resources.
The method of claim 17, wherein transmitting the preamble comprises:

comparing the transmission power level with a threshold level;

in accordance with a determination that the transmission power level exceeds the threshold level, selecting, based on the configuration, the preamble reserved for the transmission power level;

transmitting the preamble.
The method of claim 17, further comprising:

in response to detecting a failure in receiving a response to the preamble from the second device, selecting a further transmission power level higher than the transmission power level;

selecting a further subset of resources based on the further transmission power level and the configuration; and

transmitting a further preamble at the further transmission power level using the further subset of resources.
The method of claim 19, further comprising:

in response to detecting a failure in receiving a further response to the further preamble from the second device, selecting a further enhancement level from the plurality of coverage enhancement levels.
The method of claim 17, further comprising:

receiving, from the second device, information indicating a gap between a set of repetition transmissions on an uplink shared channel; and

performing the repetition transmissions on the uplink shared channel based on the gap.
The method of claim 17, further comprising:

receiving a response to the preamble from the second device, the response indicating whether power boosting is applicable to the uplink transmission; and

transmitting a second signal on an uplink shard channel based on the response.
The method of claim 22, wherein if the power boosting is applicable to the uplink transmission, the response comprises at least one of:

a start offset for transmission on the uplink shared channel access channel,

a target transmission power level on the uplink shared channel,

a duty-cycle offset for transmission on the uplink shared channel, and/or

a gap between a set of repetition transmissions on the uplink shared channel.
The method of claim 17, wherein the resources comprise at least one of: time-domain resources, frequency-domain resources and/or a preamble index.
The method of claim 17, wherein the first device comprises a terminal device and the second device comprises a network device.
A method comprising:

generating, at a second device, a configuration of a random access channel, the configuration indicating resources allocated to a plurality of coverage enhancement levels;

transmitting the configuration to a first device; and

receiving, from the first device, a preamble for an uplink transmission at a transmission power level using a subset of resources, the subset of resources being determined based on the configuration.
The method of claim 26, wherein receiving the preamble comprises:

in accordance with a determination that the preamble is for the transmission power level, determining that the transmission power level exceeds a threshold level.
The method of claim 26, further comprising:

generating information indicating a gap between a set of repetition transmissions on the uplink shared channel; and

transmitting the information to the first device.
The method of claim 26, further comprising:

generating a response to the preamble based on the transmission power level, the response indicating whether power boosting is applicable to the uplink transmission; and

transmitting the response to the first device.
The method of claim 29, wherein if the power boosting is applicable to the uplink transmission, the response comprises at least one of:

a start offset for transmission on the uplink shared channel access channel,

a target transmission power level on the uplink shared channel,

a duty-cycle offset for transmission on the uplink shared channel, and/or

a gap between a set of repetition transmissions on the uplink shared channel.
The method of claim 26, wherein the resources comprise at least one of: time-domain resources, frequency-domain resources and/or a preamble index.
The method of claim 26, wherein the first device comprises a terminal device and the second device comprises a network device.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by an apparatus, causing the apparatus to perform the method of any one of claims 17-25.
A computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by an apparatus, causing the apparatus to perform the method of any one of claims 26-32.
An apparatus comprising means for performing a process according to any of claims 17-25.
An apparatus comprising circuitry configured to cause the apparatus to perform a process according to any of claims 17-25.
An apparatus comprising means for performing a process according to any of claims 26-32.
An apparatus comprising circuitry configured to cause the apparatus to perform a process according to any of claims 26-32.