CN111357376A - Machine Type Communications Physical Downlink Control Channel Commands - Google Patents

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 start 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 repeated value may be used by the user equipment while another repeated value is used for the instruction to start random access. Additionally, the method may include: transmitting a random access preamble from the user equipment to the network entity on the physical random access channel using the determined timing.

Description

Machine Type Communications 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 order in enhanced machine type communications.

Description of Related Art

In 3rd Generation Partnership Project (3GPP) technologies such as Long Term Evolution (LTE) and Long Term Evolution-Advanced (LTE-A), random access procedures are typically used via Physical Random Access Channel (PRACH) or narrowband physical random access The access channel (NPRACH) connects the user equipment to the network. Although the random access procedure is usually 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 is initiated at the network when the user equipment is out of sync with the network, and when there is a downlink data transmission that the network needs to send to the user equipment.

A PDCCH command is a procedure used by the network to initiate random access procedures at the user equipment, thereby synchronizing the user equipment's uplink and/or downlink transmissions 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 send the random access preamble to the network entity using the preamble index included in the PDCCH order. The network entity then responds to the random access preamble with a random access response message that includes the new timing advance value used by the user equipment to synchronize uplink and/or downlink transmissions.

Enhanced machine type communication is communication between user devices that requires little human intervention. The machine type communication device is capable of receiving PDCCH commands from network entities over the MTC Physical Downlink Control Channel (MPDCCH) or Narrowband Physical Downlink Control Channel (NPDCCH). Specifically, a MTC device may use the PDCCH order to synchronize its uplink transmission with the network.

SUMMARY OF THE INVENTION

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

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

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

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

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

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

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

In some embodiments, an apparatus may include means for sending an instruction from a network entity to a user equipment to initiate random access using another number of repetitions different from the repetition value. The apparatus can also include means for receiving, at a network entity, a random access preamble from a user equipment via a physical random access channel in accordance with the 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 procedure may include sending an instruction from the network entity to the user equipment to start random access using another number of repetitions different from the repetition value. The process may also include receiving, at the network entity, the random access preamble from the user equipment via a physical random access channel according to the timing used to transmit the repetition value based random access preamble.

According to certain other embodiments, a computer program product encodes instructions for performing a process. The procedure may include sending an instruction from the network entity to the user equipment to start random access using another number of repetitions different from the repetition value. The process may also include receiving, at the network entity, the random access preamble from the user equipment via a physical random access channel according to the timing used to transmit the repetition value based random access preamble.

Description of drawings

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

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

FIG. 2 shows an example of a flow diagram in accordance with some embodiments.

FIG. 3 shows an example of a flow diagram in accordance with some embodiments.

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

Detailed ways

Certain embodiments may relate to the 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 a PRACH/NPRACH transmission. MPDCCH, NPDCCH and/or PDCCH may be generally referred to below as PDCCH, and NPRACH and/or PRACH may be generally referred to below as PRACH. While 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 body. Additionally, while some of the embodiments described below are related 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 the random access procedure is initiated by the PDCCH order in subframe n and/or the reception of the PDCCH order in subframe n is completed, the UE in the first subframe n+k ₂ (k A random access preamble is sent in ₂ ≥ 6), where PRACH resources are available. In other words, 3GPP TS 36.213 describes that PRACH resources are available 6 or more subframes after subframe n. A 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 process 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, MPDCCH may be simply referred to as PDCCH. Because PRACH/NPRACH transmissions are triggered by PDCCH orders, the timing of MPDCCH/NPDCCH reception determines when PRACH/NPRACH transmissions may occur. As discussed above, the PDCCH order ends in subframe n, which means that the timing of the PRACH transmission can be determined based on when the PDCCH order ends. However, since the number of repetitions of the MPDCCH is not known by the UE but only by the network, the UE does not know when the PDCCH order ends and when the PRACH transmission starts.

比特，其中

代表下行链路带宽配置，以资源块的数目来表示。另外，6-1A格式可以包括6比特的前导码索引、4比特的PRACH掩码索引、2比特用于开始覆盖增强等级。被用于物理下行链路共享信道的紧凑调度指派的DCI格式6-1A中的所有剩余比特可以被设置为零。The PDCCH order may be transmitted to the UE in various 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 the NB-IoT DCI format. The DCI corresponding to the PDCCH order may be carried by the MPDCCH. As described in section 5.3.3.1.12 of 3GPP TS36.212, Format 6-1A is only scrambled if the Format 6-1A Cyclic Redundancy Check (CRC) is scrambled by the Cell Radio Network Temporary Identity (C-RNTI) It can only be used for random access procedure initiated by PDCCH order. 3GPP TS 36.212 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:

bits, where

Represents the downlink bandwidth configuration, expressed in 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 the start coverage enhancement level. All remaining bits in DCI format 6-1A used for the compact scheduling assignment of the physical downlink shared channel may be set to zero.

重复的开始子帧。

可以是UE可以开始经由PRACH发送数据的子帧。3GPP TS 36.211以引用的方式全文并入。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 as

Repeated start subframe.

It may be the subframe in which the UE may start sending data via PRACH. 3GPP TS 36.211 is incorporated by reference in its entirety.

Therefore, in some embodiments, the start subframe of PRACH transmission may be determined by the end of repetition of PDCCH orders and the start subframe periodicity of PRACH. However, both DCI formats 6-1A and 6-1B do not include a DCI subframe repetition number field. This means that the UE may not be notified of the end subframe of the PDCCH order and therefore may not know the start subframe of the PRACH transmission. This lack of knowledge by the UE may result in erroneous and conflicting operations by both the UE and the network entity sending the PDCCH order.

Some of the embodiments described below may be used in any communication system in which the number of DCI subframe repetitions or the number of PDCCH order repetitions is unknown. Embodiments help to ensure correct operation for eMTC PDCCH orders as it is not clear when the UE should send PRACH in response to receipt of the order. This can help achieve common knowledge of PRACH transmission timing between the UE and the network entity.

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

The eNB may expect the UE to transmit PRACH between subframe numbers 128 to 255 of the second search space. Despite the eNB's expectation of this, the UE may be able to correctly decode the MPDCCH in the first MPDCCH candidate with 64 repetitions. When the UE decodes the MPDCCH correctly in the first MPDCCH with 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 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 may not be expected by the eNB.

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

To prevent the above-mentioned complexities and errors, some embodiments may improve the PDCCH order. In particular, some embodiments may configure a repetition value to the UE in order to determine PRACH timing. For example, the repetition value may be the 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 the maximum number of repetitions configured for the UE-specific search space for MPDCCH.

In some embodiments, the UE may be informed of Rmax via an RRC parameter mPDCCH-NumRepetition or nPDCCH-NumRepetitions, which may be configured by a network entity such as an eNB. nPDCCH-NumRepetitions may be a parameter used in NB-IoT. Using Rmax, certain embodiments may resolve or help prevent ambiguity between PRACH timing as perceived by an eNB and a UE, such as an eMTC UE. Certain embodiments allow the UE to use repetition values, 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 according to the repetition value, such as Rmax. Therefore, another number of repetitions for the PDCCH order may be different from Rmax for the PRACH timing assumption. The above-described embodiments allow to solve current problems without having to extend DCI.

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

FIG. 2 shows an example of a flow diagram in accordance with some embodiments. In particular, Figure 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 the 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 initiate 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 the configured maximum repetition value. The PDCCH commands may be formatted according to DCI formats 6-1A, 6-1B or N1. In some embodiments, the actual repetition value may be indicated in the Downlink Control Information (DCI) Subframe Repetitions field included in the 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 used by the network entity to determine the repetition of an instruction to start random access, such as a PDCCH order. For example, the number of times the network is used may be a fraction of a 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 repetition value than the repetition value used by the UE to determine the timing (such as PRACH timing) to send the random access preamble for instructions to start random access (such as a PDCCH order). repeat times.

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 criteria set by a network operator or a standards-setting body. Both the UE and the network entity may be configured with or have access to duplicate values. In some embodiments, the score for duplicate values 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, while 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 the timing for transmitting the random access preamble, eg, PRACH timing, based on the repetition value of the PDCCH. This repetition value is used by the user equipment and the other repetition value is used for the instruction to start random access. In other words, the UE may use an assumed repetition value to determine the timing of the random access preamble, while the network may use another repetition value, separate or different, for the instruction to start random access. Another repetition value for the instruction to initiate random access may be a fraction of the repetition value of the timing used to transmit 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 PRACH timing. Transmission of the preamble from the UE to the network entity using PRACH timing may be used to synchronize uplink transmissions from the UE to the network entity. In other words, the transmission of the preamble may be part of the random access operation.

In some embodiments, the transmission of the preamble may occur on the beginning subframe of 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 after 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, and for NB-IoT, the predefined number of subframes may be 8. In other words, the start subframe of PRACH may be later than the subframe Rmax+6 or Rmax+8, for example. The periodicity of the starting subframe may be configured by the network entity. However, in other embodiments, the periodicity may not be configured by the network.

FIG. 3 shows an example of a flow diagram in accordance with some embodiments. In particular, Figure 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 for the instruction to initiate 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 use the repetition value to transmit the random access preamble regardless of 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 the downlink control information subframe repetition number field, which is included in the downlink control information format 6-1A, 6-1B or N1. In step 320, the network entity may receive the random access preamble from the UE via the physical random access channel according to the timing used to transmit the random access preamble, the random access preamble being based on the repetition value. In other words, the UE may assume the repetition value regardless of another repetition value used by the network entity to send the random access instruction. The reception of the preamble may occur on the start subframe of the PRACH and/or the start subframe may be determined based on the maximum repetition value of the PDCCH or the periodicity of the start subframe.

In step 330, the network entity may decode the random access preamble sent from the UE via PRACH with a specific number of repetitions according to the coverage enhancement level of the UE. The network entity may then transmit a random access response from the network entity 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 from the user equipment to the network entity.

FIG. 4 shows an example of a system according to some embodiments. It should be understood that each block in Figures 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 network entity is shown for illustration purposes. A 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, designated 411 and 421, respectively. At least one memory may be provided in each device, denoted 412 and 422, respectively. 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 to each device. Higher class UEs typically include multiple antenna panels. For example, other configurations of these devices may be provided. For example, in addition to wireless communication, network entity 420 and UE 410 may be otherwise configured for wired communication, and in this case, antennas 414 and 424 may represent any form of communication hardware and are not limited to antennas.

Transceivers 413 and 423 may each independently be a transmitter, a receiver, or both, or a unit or device that may be 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) can also be implemented as a remote radio head, which is not located in the device itself, but eg in an electric pole. Operations and functionality can 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 situation to situation. One possible use is for network nodes to deliver local content. One or more of the functionalities may also be implemented as virtual application(s) in software that may run on the server.

The user device or user equipment may be a mobile station (MS) such as a mobile phone or smart phone or a multimedia device, a computer such as a tablet computer equipped with wireless communication capabilities, a personal data or digital assistant (PDA) equipped with wireless communication capabilities, Portable media players, digital cameras, pocket cameras, navigation units 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 IoT device, such as sensors, meters or actuators, 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 carrying out the embodiments described above with respect to Figures 1-3. In some embodiments, an apparatus may include at least one memory including computer program code and at least one processor. The at least one memory including computer program code can be configured to, in conjunction with the at least one processor, cause an apparatus to perform at least any of the processes described herein. For example, the device may be user equipment 410 or network entity 420 .

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 Arrays (FPGAs), digital enhancement circuits, or similar devices or combinations 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 (eg, 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 on a single integrated circuit as the processor, or it may be separate from it. Furthermore, computer program instructions, which may be stored in memory and processed by a processor, may be in any suitable form of computer program code, eg, a computer program written or interpreted in any suitable programming language. The memory or data storage entity is usually internal, but can also be external or a combination thereof, such as where additional storage capacity is obtained from a service provider. Memory can be fixed or removable.

The memory and computer program instructions may be configured using 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 (eg, see FIGS. 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 either A computer program, when executed in hardware, can perform processes, such as any 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 above procedures. Computer programs can be encoded in a programming language, which can be a high-level programming language, such as objective-C, C, C++, C#, Java, etc., or a low-level programming language, such as machine language or assembler. Alternatively, some embodiments may be implemented entirely in hardware.

Furthermore, although FIG. 4 shows a system including a network entity 420 and a 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 user equipment and network entities, such as relay nodes. In addition to the communication network entity 420, the UE 410 may also be provided with various 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 significantly improve 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 prevent ambiguity between the network and the UE regarding the starting subframe of PRACH. This can help reduce the number of erroneous PRACH transmissions while simplifying PDCCH orders. This network simplification and error reduction will help reduce the amount of resources used by the network, thereby significantly improving the operation of the entire network as well as the network entities included in the network and the eMTC UEs communicating with the network. Additionally, certain 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 features, structures or characteristics of certain embodiments described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, throughout this specification, use of the phrases "some embodiments," "some embodiments," "other embodiments," or other similar language refers to the fact that a particular feature, structure, or characteristic described in connection with this embodiment may Included in at least one embodiment of the present invention. Thus, appearances of the phrases "in some embodiments," "in some embodiments," "in other embodiments," or other similar language throughout this specification are not necessarily referring to the same group of embodiments, and the description The 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 invention as described above may be practiced with steps in a different order and/or with hardware elements in configurations other than those disclosed. Therefore, although this invention has been described based on these preferred embodiments, it would be obvious to those skilled in the art that certain modifications, variations and alternative constructions would be apparent without departing from the spirit and scope of this invention. While many of the above embodiments are directed to 3GPP LTE, LTE-A and eMTC technologies, other embodiments may also be applied to any other 3GPP technologies, such as 5G or NR technologies, fourth generation (4G), third generation (3G) and / or Internet of Things.

Part of the glossary

3GPP 3rd Generation Partnership Program

LTE Long Term Evolution

eMTC Enhanced Machine Type Communication

NB-IoT Narrowband Internet of Things

NPDCCH Narrowband Physical Downlink Control Channel

eNB 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 (30)

1. A method comprising: receiving, at the user equipment, an instruction from a network entity to initiate random access; After receiving the instruction, the timing for transmitting the random access preamble is determined at the user equipment based on a repetition value of the physical downlink control channel, wherein the repetition value is used by the user equipment, and another repetition value is used for the instruction to initiate the random access; and The random access preamble is transmitted from the user equipment to the network entity on a physical random access channel using the determined timing. 2. The method of claim 1, wherein the repetition value is a configured maximum repetition value. 3. The method of claim 1 or 2, wherein the further repetition value of the instruction to start the random access is used for the timing of the transmission of the random access preamble Fraction of the repeat value. 4. The method of claims 1-3, wherein the instruction to initiate the random access is a physical downlink control channel command. 5. The method of any of claims 1-4, wherein the timing for the random access preamble is physical random access channel timing. 6. The method of any of claims 1-5, wherein the physical downlink control channel is a machine type communication physical downlink control channel or a narrowband physical downlink control channel. 7. The method of any of claims 1-6, wherein the transmission of the preamble occurs on a start subframe of the physical random access channel. 8. The method of claim 7, wherein the starting subframe is determined based on at least one of: the repetition value of the physical downlink control channel, and a physical random access channel repetition number or the period of the start subframe. 9. The method of claim 8, wherein the period of the start subframe is configured by the network entity. 10. The method of any of claims 6-9, wherein the starting subframe of the physical random access channel is later than a user equipment-specific search space on the physical downlink control channel A predefined number of subframes after the end subframe of . 11. The method of any one of claims 1-10, further comprising: At the user equipment, the physical downlink control channel is decoded using the repetition value to determine the instruction to initiate random access. 12. The method of any of claims 1-11, wherein the repetition value defines the user equipment specific search space for the physical downlink control channel. 13. The method of any one of claims 1-12, further comprising: The repeat value is determined at the user equipment. 14. The method of claim 13, wherein the repetition value is determined based on a message received from the network entity. 15. The method of any of claims 1-7 and 10, wherein the repetition value is indicated in a downlink control information subframe repetition number field, the downlink control information subframe repetition number The fields are included in the downlink control information format 6-1A, 6-1B or N1. 16. The method according to any of claims 1-15, wherein the preamble is transmitted from the user equipment to the network entity using the determined timing to cause the user equipment to The uplink transmissions between the network entities are synchronized. 17. The method of any of claims 1-16, wherein the user equipment is an enhanced machine type communication user equipment or an enhanced coverage user equipment, or a narrowband IoT user equipment. 18. A method comprising: transmitting an instruction to start random access from the network entity to the user equipment using another number of repetitions different from the repetition value; The random access preamble from the user equipment is received at the network entity via a physical random access channel according to the timing for transmitting the random access preamble based on the repetition value. 19. The method of claim 18, wherein the repetition value is a configured maximum repetition value. 20. The method of claim 18 or 19, wherein the further repetition value of the instruction to start the random access is the determined value used for the random access preamble Fraction of the repeat value for the timing. 21. The method of any one of claims 18-20, further comprising: The random access preamble received from the user equipment via the physical random access channel is decoded using a specific number of repetitions according to the coverage enhancement level of the user equipment. 22. The method of any one of claims 18-21, further comprising: Based on the decoded preamble, a random access response is transmitted from the network entity to the user equipment. 23. The method of any of claims 18-22, wherein the repetition value is indicated in a Downlink Control Information Subframe Repetitions field, the Downlink Control Information Subframe Repetitions field being Included in downlink control information format 6-1A, 6-1B or N1. 24. The method according to any of claims 18-23, wherein the random access response is transmitted from the network entity to the user equipment for enabling communication between the user equipment and the network entity Uplink transmission synchronization between 25. The method of any of claims 18-24, wherein the reception of the random access preamble occurs on a starting subframe of the physical random access channel. 26. An apparatus comprising: at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to perform at least a process, the process comprising the method of any of claims 1-25. 27. A non-transitory computer-readable medium encoding instructions that, when executed in hardware, perform a process, the process comprising any of claims 1-25 method described in item. 28. An apparatus comprising means for performing the method of any of claims 1-25. 29. A computer program product encoding instructions for performing a process comprising the method of any of claims 1-25. 30. A computer program product embodied in a non-transitory computer readable medium and encoding instructions that, when executed in hardware, perform a process, the process comprising any one of claims 1-25 the method described.

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