CN111357376B

CN111357376B - Machine type communication physical downlink control channel commands

Info

Publication number: CN111357376B
Application number: CN201780096901.7A
Authority: CN
Inventors: 姚春海; R·拉塔萨克
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2017-11-17
Filing date: 2017-11-17
Publication date: 2023-11-28
Anticipated expiration: 2037-11-17
Also published as: EP3711428A4; WO2019095320A1; EP3711428A1; CN111357376A

Abstract

Various communication systems may benefit from improved random access related communications. For example, certain embodiments may benefit from improved physical downlink control channel commands in enhanced machine type communications. In some embodiments, a method may include: an instruction to initiate random access is received at a user equipment from a network entity. The method may further comprise: after receiving the instruction, determining, at the user equipment, a timing for transmitting the random access preamble based on the repetition value of the physical downlink control channel. The repetition value may be used by the user equipment and another repetition value is used for the instruction to start random access. Additionally, the method may include: the random access preamble is transmitted from the user equipment to the network entity on the physical random access channel using the determined timing.

Description

Machine type communication physical downlink control channel commands

Background

FIELD

Various communication systems may benefit from improved random access related communications. For example, certain embodiments may benefit from improved physical downlink control channel commands (physical downlink control channel order) in enhanced machine type communications.

Description of the Related Art

In third generation partnership project (3 GPP) technologies such as Long Term Evolution (LTE) and long term evolution-advanced (LTE-a), a random access procedure is typically used to connect a user equipment to a network via a Physical Random Access Channel (PRACH) or a Narrowband Physical Random Access Channel (NPRACH). Although the random access procedure is typically triggered or initiated by the user equipment, in some cases the random access procedure may be triggered or initiated by the network. A random access procedure may be initiated at the network when the user equipment is out of synchronization with the network, and when there is a downlink data transmission that the network needs to send to the user equipment.

The PDCCH order is a procedure used by the network to initiate a random access procedure at the user equipment, thereby synchronizing uplink and/or downlink transmissions of the user equipment with network entities located within the network. The initiated random access procedure may be a non-contention random access procedure. The user equipment receiving the PDCCH order may transmit a random access preamble to the network entity using a preamble index included in the PDCCH order. The network entity then responds to the random access preamble with a random access response message comprising a new timing advance value, which is used by the user equipment to synchronize uplink and/or downlink transmissions.

Enhanced machine type communication is communication between user equipment that requires little human intervention. The machine type communication device can receive PDCCH orders from a network entity through an MTC Physical Downlink Control Channel (MPDCCH) or a Narrowband Physical Downlink Control Channel (NPDCCH). In particular, a machine type communication device may use PDCCH order to synchronize its uplink transmissions with the network.

Disclosure of Invention

According to some embodiments, an apparatus may comprise at least one memory including computer program code and at least one processor. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to receive an instruction from a network entity to initiate random access. The at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to determine a timing for transmitting the random access preamble based on a repetition value of the physical downlink control channel after receiving the instruction. The repetition value may be used by the user equipment and another repetition value is used for the instruction to start random access. In addition, the at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to transmit a random access preamble from the user equipment to the network entity on the physical random access channel using the determined timing.

In some embodiments, a method may include: an instruction to initiate random access is received at a user equipment from a network entity. The method may further comprise: after receiving the instruction, determining, at the user equipment, a timing for transmitting the random access preamble based on the repetition value of the physical downlink control channel. The repetition value may be used by the user equipment and another repetition value is used for the instruction to start random access. Additionally, the method may include: the random access preamble is transmitted from the user equipment to the network entity on the physical random access channel using the determined timing.

In some embodiments, an apparatus may comprise: means for receiving, at a user equipment, an instruction from a network entity to start random access. The apparatus may further include: means for determining, at the user equipment, a timing of transmitting the random access preamble based on the repetition value of the physical downlink control channel after receiving the instruction. The repetition value may be used by the user equipment and another repetition value is used for the instruction to start random access. In addition, the apparatus may include: means for transmitting a random access preamble from the user equipment to the network entity on the physical random access channel using the determined timing.

According to some embodiments, a non-transitory computer-readable medium encodes instructions that, when executed in hardware, perform a process. The process may include receiving, at a user equipment, an instruction from a network entity to initiate random access. The process may further include: after receiving the instruction, determining, at the user equipment, a timing for transmitting the random access preamble based on the repetition value of the physical downlink control channel. The repetition value may be used by the user equipment and another repetition value is used for the instruction to start random access. In addition, the process may include: the random access preamble is transmitted from the user equipment to the network entity on the physical random access channel using the determined timing.

According to certain other embodiments, a computer program product may encode instructions for performing a process. The process may include receiving, at a user equipment, an instruction from a network entity to initiate random access. The process may further include: after receiving the instruction, determining, at the user equipment, a timing of transmitting the random access preamble based on the repetition value of the physical downlink control channel. The repetition value may be used by the user equipment and another repetition value is used for the instruction to start random access. In addition, the process may include: the random access preamble is transmitted from the user equipment to the network entity on the physical random access channel using the determined timing.

According to some embodiments, an apparatus may comprise at least one memory including computer program code and at least one processor. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus at least to transmit to the user equipment an instruction to start random access using another number of repetitions different than the repetition value. The at least one memory and the computer program code may also be configured to, with the at least one processor, cause the apparatus at least to receive a random access preamble from a user equipment via a physical random access channel according to a timing for transmitting a repetition value based random access preamble.

In some embodiments, a method may include transmitting an instruction to start random access from a network entity to a user equipment using another number of repetitions different from a repetition value. The method may further comprise receiving, at the network entity, a random access preamble from the user equipment via the physical random access channel according to a timing for transmitting the repetition value based random access preamble.

In some embodiments, an apparatus may include means for transmitting an instruction to start random access from a network entity to a user equipment using another number of repetitions different from a repetition value. The apparatus may also include means for receiving, at the network entity, a random access preamble from the user equipment via the physical random access channel according to a timing for transmitting the repetition value based random access preamble.

According to some embodiments, a non-transitory computer readable medium encodes instructions that, when executed in hardware, perform a process. The process may include transmitting an instruction to start random access from the network entity to the user equipment using another number of repetitions than the repetition value. The method may further include receiving, at the network entity, a random access preamble from the user equipment via the physical random access channel according to a timing for transmitting the repetition value based random access preamble.

According to certain other embodiments, a computer program product may encode instructions for performing a process. The process may include transmitting an instruction to start random access from the network entity to the user equipment using another number of repetitions than the repetition value. The method may further include receiving, at the network entity, a random access preamble from the user equipment via the physical random access channel according to a timing for transmitting the repetition value based random access preamble.

Drawings

For a proper understanding of the invention, reference should be made to the accompanying drawings, in which:

fig. 1 illustrates an example of a timing relationship between PDCCH order and PRACH, according to some embodiments.

FIG. 2 illustrates an example of a flow chart according to some embodiments.

FIG. 3 illustrates an example of a flow chart according to some embodiments.

FIG. 4 illustrates an example of a system according to some embodiments.

Detailed Description

Some embodiments may relate to a relationship between an instruction to start random access, such as an MPDCCH/NPDCCH/PDCCH order, and a timing for transmitting a random access preamble, such as PRACH/NPRACH transmission. MPDCCH, NPDCCH and/or PDCCH may be referred to below generally as PDCCH, while NPRACH and/or PRACH may be referred to below generally as PRACH. Although some embodiments refer to MPDCCH, NPDCCH, PDCCH, NPRACH and PRACH, some other embodiments may use any other type of channel provided by 3GPP or any other standards-setting authority. In addition, while some embodiments described below relate to 3GPP LTE and LTE-A, other embodiments may be applied to 3GPP fifth generation (5G) or New Radio (NR) technologies.

Section 6.1.1 of 3GPP TS 36.213 describes that when a random access procedure is initiated by a PDCCH order in subframe n and/or reception of a PDCCH order in subframe n is over, the UE is in the first subframe n+k ₂ (k ₂ And 6), transmitting a random access preamble, wherein PRACH resources are available. In other words, 3gpp TS 36.213 describes that PRACH resources are available 6 or more subframes after subframe n. The UE described in 3gpp TS 36.213 is a non-Bandwidth Limited (BL) or non-Coverage Enhanced (CE) User Equipment (UE). The BL/CE UE may be a machine type communication device. Section 16.3.2 of 3GPP TS 36.213 describes a similar procedure for narrowband Internet of things (NB-IoT). 3GPP TS 36.213 is incorporated by reference in its entirety.

In some embodiments, the PDCCH may be an enhanced machine type communication (eMTC) PDCCH (MPDCCH) or NPDCCH. Hereinafter, the MPDCCH may be simply referred to as PDCCH. Because the PRACH/NPRACH transmission is triggered by the PDCCH order, the timing of MPDCCH/NPDCCH reception determines the time at which the transmission of the PRACH/NPRACH may occur. As discussed above, the PDCCH order ends in subframe n, which means that the timing of PRACH transmission may be determined based on the time at which the PDCCH order ends. However, since the number of repetitions of MPDCCH is not known to the UE but only to the network, the UE does not know when the PDCCH order ends and when the PRACH transmission starts.

The PDCCH order may be transmitted to the UE in a variety of different formats. For example, one such format may be Downlink Control Information (DCI) format 6-1A. Another example may be DCI format 6-1B or N1, where N1 may be an NB-IoT DCI format. The DCI corresponding to the PDCCH order may be carried by the MPDCCH. 5.3 as 3GPP TS36.212As described in section 3.1.12, format 6-1A may be used for a random access procedure initiated by a PDCCH order only when format 6-1A Cyclic Redundancy Check (CRC) is scrambled by a cell radio network temporary identity (C-RNTI). The 3gpp TS36.212 is incorporated by reference in its entirety. The remaining fields in the 6-1A format may include resource block assignments determined by the following equation:bit of>Representing the downlink bandwidth configuration, expressed in terms of the number of resource blocks. In addition, the 6-1A format may include a 6-bit preamble index, a 4-bit PRACH mask index, and 2 bits for starting coverage enhancement levels. All remaining bits in DCI format 6-1A used for compact scheduling assignment of a physical downlink shared channel may be set to zero.

Section 5.7.1 of 3GPP TS 36.211 further describes that for BL/CE UEs such as MTC devices, only a subset of subframes are allowed for preamble transmission while also being allowed to function as wellRepeated start subframes. />It may be a subframe in which the UE may start transmitting data via the PRACH. 3GPP TS 36.211 is incorporated by reference in its entirety.

Thus, in certain embodiments, the starting subframe of PRACH transmission may be determined by the end of the repetition of the PDCCH order and the starting subframe periodicity of the PRACH. However, neither DCI format 6-1A nor 6-1B includes a DCI subframe repetition number field. This means that the UE may not be informed of the ending subframe of the PDCCH order, and thus may not be aware of the starting subframe of the PRACH transmission. This lack of knowledge of the UE may result in erroneous and conflicting operations by both the UE and the network entity sending the PDCCH order.

Some embodiments described below may be used in any communication system in which the DCI subframe repetition number or PDCCH order repetition number is unknown. Embodiments help ensure proper operation for eMTC PDCCH orders, as it is unclear when a UE should send PRACH in response to receipt of an order. This may help enable a common knowledge of PRACH transmission timing between the UE and the network entity.

Fig. 1 illustrates an example of a timing relationship between PDCCH order and PRACH transmission, according to some embodiments. In particular, fig. 1 illustrates an example of PDCCH order reception and corresponding PRACH transmission. In the example shown in fig. 1, a network entity, such as an enhanced NodeB (eNB), may configure MPDCCH 110 with 256 repeated PDCCH orders. The UE may assume that the PDCCH order is capable of 256 repetitions. If the decoding of the PRACH order by the UE does not reveal that the PDCCH order can be repeated 256 times, the UE may not transmit on the PRACH.

The eNB may expect the UE to transmit the PRACH between subframe numbers 128 to 255 of the second search space. Although the eNB may expect this, the UE may be able to correctly decode the MPDCCH in the first MPDCCH candidate at 64 repetitions. When the UE correctly decodes the MPDCCH in the first MPDCCH at 64 repetitions, the UE may transmit the PRACH between subframe numbers 128 to 255 of the first MPDCCH search space. In another example, the UE may transmit the PRACH from subframe numbers 0 to 127 of the second MPDCCH search space and/or from subframe numbers 128 to 255 of the second MPDCCH search space. In other words, the user equipment may have two different options for transmitting on PRACH that the eNB may not expect.

As can be seen in fig. 1, the eNB and UE may have different understandings of the starting subframe of the PRACH transmission. This may result in, for example, the network entity attempting to decode the PRACH while the PDCCH order is still being transmitted. This is because the UE may not know subframe n, which is a subframe marking the end of PDCCH order reception. Thus, the implementation of a network entity such as an eNB may become complex and, depending on the UE implementation, possible errors may occur.

To prevent the complexity and errors described above, some embodiments may improve PDCCH order. In particular, certain embodiments may configure the UE with a repetition value in order to determine PRACH timing. For example, the repetition value may be a configured maximum repetition value (Rmax). In some embodiments, the MPDCCH repetition number or value may be 1, 2, 4, 8, 16, 32, 64, 128, or 256.Rmax may be a maximum number of repetitions configured for a UE-specific search space for MPDCCH.

In some embodiments, the UE may be notified of Rmax via RRC parameters mppdcch-NumRepetition or nppdcch-NumRepetition that may be configured by a network entity such as an eNB. nPDCCH-NumRepetitions may be parameters used in NB-IoT. Using Rmax, certain embodiments may resolve or help prevent ambiguity between PRACH timing perceived by an eNB and a UE (such as eMTC UE). Some embodiments allow the UE to use a repetition value, such as Rmax, independent of the repetition used by the network entity. In other words, the network entity may use a fraction of the repetition value for the PDCCH order, but may then determine the PRACH timing from the repetition value (such as Rmax). Thus, another number of repetitions for the PDCCH order may be different from Rmax for the PRACH timing assumption. The above-described embodiments allow solving the current problem without having to extend DCI.

Certain other embodiments may improve the PDCCH order format. In particular, some embodiments may introduce a field to indicate the number of repetitions in the downlink control information. The field may be a DCI subframe repetition number field and may be included in DCI format 6-1A, 6-1B or N1. By adding the DCI subframe repetition number field, ambiguity between PRACH or NPRACH timing perceived by the eNB and UE may be resolved.

FIG. 2 illustrates an example of a flow chart according to some embodiments. In particular, fig. 2 illustrates a method or process performed by a UE (such as an eMTC or NB-IoT UE or enhanced coverage user equipment). In step 210, the UE may receive an instruction from a network entity to start random access. For example, the instruction to start random access may take the form of a PDCCH order. In some embodiments, the UE may decode the PDCCH to determine an instruction to start random access, as shown in step 220. When decoding the PDCCH to determine an instruction to start random access, such as a PDCCH order, the UE may use the repetition value as a reference timing for random access. For example, the repetition value may define a UE-specific search space for the PDCCH. In some embodiments, the repetition value may be a configured maximum repetition value. The PDCCH order may be formatted according to DCI formats 6-1A, 6-1B or N1. In some embodiments, the actual repetition value may be indicated in a Downlink Control Information (DCI) subframe repetition number field included in format 6-1A, 6-1B, or N1 downlink control information.

In some embodiments, the repetition value assumed or used by the UE may be different from another number of repetitions of the repetition of the instruction (such as the PDCCH order) used by the network entity to determine to start random access. For example, the number of network uses may be a fraction of the repetition value assumed or used by the UE. In other words, the UE and the network entity may use a different number of repetitions or another number of repetitions for the instruction to start random access, such as a PDCCH order, than the repetition value used by the UE to determine the timing to transmit the random access preamble, such as PRACH timing.

In some embodiments, the UE may determine the repetition value. For example, the repetition value may be determined based on a message received at the UE from a network entity such as an eNB. In another example, the repetition value may be determined based on a standard set by a network operator or a standard formulation agency. Both the UE and the network entity may be configured with or may have access to the repetition value. In some embodiments, the score of the repetition value may be used by the network entity. For example, in embodiments where the repetition value is Rmax, another repetition value used by the network entity may be Rmax/8, rmax/4, rmax/2, or Rmax, and the UE may use Rmax. For example, if Rmax is 256 repetitions, the repetition value used by the network entity may be 128, 64, or 32.

In step 230, the UE may determine a timing for transmitting the random access preamble, e.g., PRACH timing, based on the repetition value of the PDCCH. The repetition value is used by the user equipment and another repetition value is used for the instruction to start random access. In other words, the UE may use the hypothesized repetition value to determine the timing of the random access preamble, and the network may use a separate or different further repetition value for the instruction to start random access. Another repetition value of the instruction for starting random access may be a fraction of a repetition value of a timing used for transmitting the random access preamble. In step 240, the UE may transmit a random access preamble from the UE to the network entity on the PRACH using the determined timing, such as the PRACH timing. The transmission of the preamble from the UE to the network entity using PRACH timing may be used to synchronize uplink transmissions between the UE to the network entity. In other words, the transmission of the preamble may be part of a random access operation.

In some embodiments, the transmission of the preamble may occur on a starting subframe of the PRACH. The starting subframe may be determined based on at least one of a repetition value of the PDCCH and/or a periodicity of the starting subframe. For example, in some embodiments, the start subframe of the physical random access channel is a predefined number of subframes later than the end subframe of the user equipment specific search space of the physical downlink control channel. For example, for eMTC, the predefined number of subframes may be 6, while for NB-IoT, the predefined number of subframes may be 8. In other words, the starting subframe of the PRACH may be later than the subframes rmax+6 or rmax+8, for example. The periodicity of the starting subframes may be configured by the network entity. However, in other embodiments, the periodicity may not be configured by the network.

FIG. 3 illustrates an example of a flow chart according to some embodiments. In particular, fig. 3 illustrates a method or process performed by a network entity, such as an eNB or fifth generation or new wireless node B (gNB). In step 310, the network entity may transmit an instruction to start random access to the UE using another number of repetitions different from the repetition value. Another repetition value of the instruction for starting random access may be a fraction of the repetition value for the determined timing of the random access preamble. In other words, the UE may transmit the random access preamble using a repetition value, despite the fact that the network entity may use a different repetition value (such as a fraction of the repetition value) to send the instruction to start random access.

The number of repetitions may be indicated in a downlink control information subframe repetition number field included in downlink control information format 6-1A, 6-1B, or N1. In step 320, the network entity may receive a random access preamble from the UE via a physical random access channel according to a timing for transmitting the random access preamble, the random access preamble being based on the repetition value. In other words, the UE may assume a repetition value regardless of another repetition value that the network entity uses to send the random access instruction. The reception preamble may occur on a starting subframe of the PRACH and/or the starting subframe may be determined based on a maximum repetition value of the PDCCH or a periodicity of the starting subframe.

In step 330, the network entity may decode the random access preamble transmitted from the UE via the PRACH at a specific number of repetitions according to the coverage enhancement level of the UE. The network entity may then transmit a random access response to the UE based on the decoded preamble, as shown in step 340. The random access response is transmitted from the network entity to the user equipment for synchronizing uplink transmissions between the user equipment to the network entity.

FIG. 4 illustrates an example of a system according to some embodiments. It is to be understood that each of the blocks of fig. 1, 2, and 3 may be implemented in various ways, or combinations thereof, such as hardware, software, firmware, one or more processors, and/or circuitry. In one embodiment, the system may include multiple devices, such as, for example, network entity 420 or UE 410. The system may include more than one UE 410 and more than one network entity 420, although only one is shown for purposes of illustration. The network entity may be a network node, access node, base station, eNB, gNB, server, host, or any other access or network node discussed herein.

Each of these devices may include at least one processor or control unit or module, indicated as 411 and 421, respectively. At least one memory, indicated as 412 and 422, respectively, may be provided in each device. The memory may include computer program instructions or computer code embodied therein. One or more transceivers 413 and 423 may be provided and each device may also include an antenna, shown as 414 and 424, respectively. Although only one antenna is shown, many antennas and multiple antenna elements may be provided for each device. Higher category UEs typically include multiple antenna panels. For example, other configurations of these devices may be provided. For example, network entity 420 and UE 410 may additionally be configured for wired communications in addition to wireless communications, and in such a case antennas 414 and 424 may illustrate any form of communications hardware and are not limited to antennas.

The transceivers 413 and 423 may be, respectively, independently a transmitter, a receiver, or both a transmitter and a receiver, or may be units or devices configured for transmission and reception. In other embodiments, the network entity may have at least one separate receiver or transmitter. The transmitter and/or receiver (in terms of radio components) may also be implemented as a remote radio head, which is not located in the device itself, but for example in an electric pole. Operations and functionality may be performed in different entities, such as nodes, hosts, or servers, in a flexible manner. In other words, the division of labor may vary from case to case. One possible use is for a network node to deliver local content. One or more of the functionalities may also be implemented as virtual application(s) in software that may run on a server.

The user device or user equipment may be a Mobile Station (MS) such as a mobile phone or a smart phone or a multimedia device, a computer such as a tablet computer provided with wireless communication capabilities, a personal data or digital assistant (PDA) provided with wireless communication capabilities, a portable media player, a digital camera, a pocket video camera, a navigation unit provided with wireless communication capabilities, or any combination thereof. In other embodiments, the UE may be a Machine Type Communication (MTC) device, eMTC UE, or an internet of things device, such as a sensor, meter, or actuator, that may not require human interaction.

In some embodiments, an apparatus, such as user equipment 410 or network entity 420, may include means for performing or conducting the embodiments described above with respect to fig. 1-3. In some embodiments, a device may include at least one memory including computer program code and at least one processor. The at least one memory including computer program code may be configured to, with the at least one processor, cause the apparatus at least to perform any of the processes described herein. For example, the device may be a user equipment 410 or a network entity 420.

The processors 411 and 421 may be embodied by any computing or data processing device, such as a Central Processing Unit (CPU), digital Signal Processor (DSP), application Specific Integrated Circuit (ASIC), programmable Logic Device (PLD), field Programmable Gate Array (FPGA), digital enhancement circuit, or the like, or a combination thereof. A processor may be implemented as a single controller, or as multiple controllers or processors.

For firmware or software, the implementation may include modules or units (e.g., procedures, functions, etc.) of at least one chipset. Memories 412 and 422 may independently be any suitable storage device such as a non-transitory computer readable medium. A Hard Disk Drive (HDD), random Access Memory (RAM), flash memory, or other suitable memory may be used. The memory may be combined as a processor on a single integrated circuit or may be separate therefrom. Furthermore, the computer program instructions may be stored in a memory and may be processed by a processor, and may be in any suitable form of computer program code, for example, a computer program written or interpreted in any suitable programming language. The memory or data storage entity is typically internal, but may also be external or a combination thereof, such as where additional storage capacity is obtained from a service provider. The memory may be fixed or removable.

The memory and computer program instructions may be configured, with a processor for a particular device, to cause a hardware device, such as network entity 420 or UE 410, to perform any of the processes described above (see, e.g., fig. 1-3). Thus, in certain embodiments, a non-transitory computer readable medium may be encoded with computer instructions or one or more computer programs (such as added or updated software routines, applets, or macros) that, when executed in hardware, may perform a process, such as any one of the processes described herein. In other embodiments, a computer program product may encode instructions for performing any of the processes described above, or a computer program product embodied in a non-transitory computer readable medium encodes instructions that, when executed in hardware, perform any of the processes described above. The computer program may be encoded in a programming language, which may be a high-level programming language such as objected C, C, C ++, c#, java, etc., or a low-level programming language such as a machine language or assembler. Alternatively, some embodiments may be implemented entirely in hardware.

Furthermore, while fig. 4 shows a system including network entity 420 and UE 410, certain embodiments may be applicable to other configurations and configurations involving additional elements, as illustrated and discussed herein. For example, there may be multiple user equipment devices and multiple network entities, or other nodes providing similar functionality, such as nodes combining the functionality of the user equipment and network entities, such as relay nodes. In addition to communication network entity 420, UE 410 may also be provided with a variety of configurations for communication. For example, UE 410 may be configured for device-to-device, machine-to-machine, and/or vehicle-to-vehicle transmissions.

The above embodiments may provide significant improvements in the operation of the network and/or the operation of user equipment and network entities included in the network. In particular, certain embodiments may help to prevent ambiguity between the network and the UE regarding the starting subframe of the PRACH. This may help reduce the number of erroneous PRACH transmissions while simplifying PDCCH order. Such network simplification and error reduction would help to reduce the amount of resources used by the network, thereby significantly improving the operation of the entire network as well as the operation of network entities included in the network and eMTC UEs communicating with the network. Additionally, some embodiments may help improve the uplink synchronization process between the network and the UE, which may also help reduce the amount of downtime experienced by the UE.

The particular features, structures, or characteristics of some embodiments described throughout the specification may be combined in any suitable manner in one or more embodiments. For example, the use of the phrases "certain embodiments," "some embodiments," "other embodiments," or other similar language throughout this specification refers to the fact that: a particular feature, structure, or characteristic described in connection with the embodiment may be included within at least one embodiment of the invention. Thus, appearances of the phrases "in certain embodiments," "in some embodiments," "in other embodiments," or other similar language throughout this specification do not necessarily refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Those of ordinary skill in the art will readily appreciate that the present invention as described above may be practiced with steps in a different order and/or with hardware elements in a different configuration than that disclosed. Thus, while the invention has been described based upon these preferred embodiments, it would be apparent to those skilled in the art that certain modifications, variations, and alternative constructions would be apparent without departing from the spirit and scope of the invention. Although many of the embodiments described above are directed to 3GPP LTE, LTE-a, and eMTC technologies, other embodiments may also be applied to any other 3GPP technology, such as 5G or NR technologies, fourth generation (4G), third generation (3G), and/or internet of things.

Partial vocabulary

3GPP third Generation partnership project

LTE long term evolution

eMTC enhanced machine type communication

NB-IoT narrowband Internet of things

NPDCCH narrowband physical downlink control channel

eNBs enhanced node B

UE user equipment

PUSCH physical uplink shared channel

DCI downlink control information

MPDCCHMTC physical downlink control channel

PRACH physical random access channel

Claims

1. An apparatus for communication, comprising:

means for receiving, at a user equipment, an instruction from a network entity to start random access, wherein a first repetition value is used for the instruction to start the random access;

means for determining, at the user equipment, a timing for transmitting a random access preamble based on a second repetition value after receiving the instruction, the second repetition value being a repetition value of a physical downlink control channel, wherein the first repetition value is a fraction of or equal to the second repetition value; and

means for transmitting the random access preamble from the user equipment to the network entity on a physical random access channel using the determined timing.

2. The apparatus of claim 1, wherein the second repetition value is a configured maximum repetition value.

3. The apparatus of claim 1, wherein the instruction to start the random access is a physical downlink control channel command.

4. The apparatus of claim 1, wherein the timing for the random access preamble is a physical random access channel timing.

5. The apparatus of claim 1, wherein the physical downlink control channel is a machine type communication physical downlink control channel or a narrowband physical downlink control channel.

6. The apparatus of claim 1, wherein the transmission of the preamble occurs on a starting subframe of the physical random access channel.

7. The apparatus of claim 6, wherein the starting subframe is determined based on at least one of: the second repetition value of the physical downlink control channel, a physical random access channel repetition number or a period of the starting subframe.

8. The apparatus of any of claims 1-7, wherein the second repetition value defines a search space for the physical downlink control channel that is specific to the user equipment.

9. The apparatus according to any of claims 1-6, wherein the second repetition value is indicated in a downlink control information subframe repetition number field included in a downlink control information format 6-1A, 6-1B or N1.

10. The apparatus of any of claims 1-7, wherein the user equipment is an enhanced machine type communication user equipment or an enhanced overlay user equipment, or a narrowband internet of things user equipment.

11. An apparatus for communication, comprising:

transmitting an instruction to start random access from the network entity to the user equipment using the first repetition value;

means for receiving, at the network entity, a random access preamble from the user equipment via a physical random access channel according to a timing for transmitting the random access preamble based on a second repetition value, wherein the first repetition value is a fraction of or equal to the second repetition value and the second repetition value is a repetition value of a physical downlink control channel.

12. The apparatus of claim 11, wherein the second repetition value is a configured maximum repetition value.

13. The apparatus according to any of claims 11-12, wherein the second repetition value is indicated in a downlink control information subframe repetition number field included in a downlink control information format 6-1A, 6-1B or N1.

14. A method of communication, comprising:

receiving, at a user equipment, an instruction from a network entity to start random access, wherein a first repetition value is used for the instruction to start the random access;

determining, at the user equipment, a timing for transmitting a random access preamble based on a second repetition value after receiving the instruction, the second repetition value being a repetition value of a physical downlink control channel, wherein the first repetition value is a fraction of or equal to the second repetition value; and

transmitting the random access preamble from the user equipment to the network entity on a physical random access channel using the determined timing.