WO2018083376A1

WO2018083376A1 - Dedicated random access channel configuration

Info

Publication number: WO2018083376A1
Application number: PCT/FI2017/050745
Authority: WO
Inventors: Ahmad AWADA; Samuli Heikki TURTINEN; Manivannan Thyagarajan; Amaanat ALI
Original assignee: Nokia Technologies Oy
Priority date: 2016-11-03
Filing date: 2017-10-30
Publication date: 2018-05-11

Abstract

Systems, methods, apparatuses, and computer program products for a dedicated random access channel (RACH) configuration are provided. One method includes configuring, by a network node, one or more user equipment (UEs) monitoring paging indicators (PIs) transmitted in a paging occasion (PO) to use different RACH configurations.

Description

DEDICATED RANDOM ACCESS CHANNEL CONFIGURATION

CROSS-REFERENCE TO RELATED APPLICATIONS:

5 This application claims priority from United States Provisional Application No. 62/416,870, filed on November 3, 2016. The entire contents of this earlier filed application are hereby incorporated by reference in their entirety.

BACKGROUND:

i o Field:

Embodiments of the invention generally relate to wireless or mobile communications networks, such as, but not limited to, the Global System for Mobile Communications (GSM)/Enhanced Data rates for GSM Evolution (EDGE) radio access network (GERAN), the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network 15 (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), LTE-A Pro, narrow band internet of things (NB-IoT), and/or 5G radio access technology or new radio access technology (NR). Some embodiments may generally relate to random access channel (RACH) configuration.

2 o Description of the Related Art:

Global System for Mobile Communications (GSM) is a standard initially developed by the European Telecommunications Standards Institute (ETSI) and later by the 3^rd Generation Partnership Project (3GPP) to describe the protocols for second-generation digital cellular networks used by mobile phones. The GSM standard originally described a digital, circuit- 25 switched network optimized for full duplex voice telephony. GSM was enhanced over time to include data communications by circuit-switched transport and then by packet data transport via General Packet Radio Services (GPRS) and Enhanced Data rates for GSM Evolution (EDGE or EGPRS). Subsequently, 3GPP developed third-generation UMTS standards followed by fourth-generation LTE-Advanced standards.

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Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) refers to a communications network including base stations, or Node Bs, and for example radio network controllers (RNC). UTRAN allows for connectivity between the user equipment (UE) and the core network. The R C provides control functionalities for one or more Node Bs. The RNC and its corresponding Node Bs are called the Radio Network Subsystem (RNS). In case of E-UTRAN (enhanced UTRAN), no RNC exists and radio access functionality is provided by an evolved Node B (eNodeB or eNB) or many eNBs. Multiple eNBs are involved for a single UE connection, for example, in case of Coordinated Multipoint Transmission (CoMP) and in dual connectivity.

Long Term Evolution (LTE) or E-UTRAN refers to improvements of the UMTS through improved efficiency and services, lower costs, and use of new spectrum opportunities. In particular, LTE is a 3 GPP standard that provides for uplink peak rates of at least, for example, 75 megabits per second (Mbps) per carrier and downlink peak rates of at least, for example, 300 Mbps per carrier. LTE supports scalable carrier bandwidths from 20 MHz down to 1.4 MHz and supports both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD).

As mentioned above, LTE may also improve spectral efficiency in networks, allowing carriers to provide more data and voice services over a given bandwidth. Therefore, LTE is designed to fulfill the needs for high-speed data and media transport in addition to high-capacity voice support. Advantages of LTE include, for example, high throughput, low latency, FDD and TDD support in the same platform, an improved end-user experience, and a simple architecture resulting in low operating costs.

Certain releases of 3GPP LTE (e.g., LTE Rel-10, LTE Rel-11, LTE Rel-12, LTE Rel-13) are targeted towards international mobile telecommunications advanced (IMT-A) systems, referred to herein for convenience simply as LTE -Advanced (LTE -A).

LTE -A is directed toward extending and optimizing the 3 GPP LTE radio access technologies. A goal of LTE -A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is a more optimized radio system fulfilling the international telecommunication union-radio (ITU-R) requirements for IMT -Advanced while maintaining backward compatibility. One of the key features of LTE-A, introduced in LTE Rel-10, is carrier aggregation, which allows for increasing the data rates through aggregation of two or more LTE carriers. 5^th generation wireless systems (5G) refers to the new generation of radio systems and network architecture. 5G is expected to provide higher bitrates and coverage than the current LTE systems. Some estimate that 5G will provide bitrates one hundred times higher than LTE offers. 5G is also expected to increase network expandability up to hundreds of thousands of connections. The signal technology of 5G is anticipated to be improved for greater coverage as well as spectral and signaling efficiency. 5G is expected to deliver extreme broadband and ultra-robust, low latency connectivity and massive networking to support the Internet of Things (IoT). With IoT and machine-to -machine (M2M) communication becoming more widespread, there will be a growing need for networks that meet the needs of lower power, low data rate, and long battery life. Narrowband IoT (NB-IoT) is envisioned to operate on 180/200 kHz channel. The deployment of NB-IoT may be in-band LTE, a guard band to LTE, UMTS or other system as well as stand-alone on a specific carrier.

SUMMARY:

One embodiment is directed to a method that may include configuring, by a network node, one or more UEs monitoring Pis transmitted in a PO to use different RACH configurations. In one embodiment, the configuring may include classifying the one or more UEs that are monitoring Pis transmitted in a PO into different sets of UEs, and configuring the UEs within the same set to apply the same RACH configuration and/or each of the sets of UEs to apply different RACH configurations. In another embodiment, the configuring of the one or more UEs to use different RACH configurations may include configuring a main RACH configuration and then allowing the UEs to decide on which resource to send the PRACH preamble following the main RACH configuration. Another embodiment is directed to an apparatus, which may include at least one processor and 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 at least to configure one or more UEs monitoring Pis transmitted in a PO to use different RACH configurations. In one embodiment, the apparatus may be controlled to configure the UEs to use different RACH configurations by classifying the one or more UEs that are monitoring Pis transmitted in a PO into different sets of UEs, and configuring the UEs within the same set to apply the same RACH configuration and/or each of the sets of UEs to apply different RACH configurations. In another embodiment, the apparatus may be controlled to configure the UEs to use different RACH configurations by configuring a main RACH configuration and then allowing the UEs to decide on which resource to send the PRACH preamble following the main RACH configuration. Another embodiment is directed to a computer program embodied on a non-transitory computer readable medium. The computer program is configured to control a processor to perform a process including configuring one or more UEs monitoring Pis transmitted in a PO to use different RACH configurations. In one embodiment, the configuring may include classifying the one or more UEs that are monitoring Pis transmitted in a PO into different sets of UEs, and configuring the UEs within the same set to apply the same RACH configuration and/or each of the sets of UEs to apply different RACH configurations. In another embodiment, the configuring of the one or more UEs to use different RACH configurations may include configuring a main RACH configuration and then allowing the UEs to decide on which resource to send the PRACH preamble following the main RACH configuration.

BRIEF DESCRIPTION OF THE DRAWINGS:

For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:

Fig. 1 illustrates an example diagram of a signalling flow for a paging procedure;

Fig. 2 illustrates an example of the RACH configuration in system information block (SIB) 2;

Fig. 3 illustrates a configuration table, according to an embodiment;

Fig. 4 illustrates a configuration table, according to another embodiment;

Fig. 5a illustrates a block diagram of an apparatus, according to one embodiment;

Fig. 5b illustrates a block diagram of an apparatus, according to another embodiment; and Fig. 6 illustrates an example of flow diagram depicting a method, according to one embodiment.

DETAILED DESCRIPTION:

It will be readily understood that the components of the invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of systems, methods, apparatuses, and computer program products for a dedicated random access channel (RACH) configuration, as represented in the attached figures and described below, is not intended to limit the scope of the invention but is representative of selected embodiments of the invention.

The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, the usage of the phrases "certain embodiments," "some 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 in at least one embodiment of the present 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 all 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. Additionally, if desired, the different functions discussed below may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the described functions may be optional or may be combined. As such, the following description should be considered as merely illustrative of the principles, teachings and embodiments of this invention, and not in limitation thereof.

The paging and, in general, provisioning of common control information in a high frequency (HF) cell where beamforming is applied will require significant overhead - the network (NW) needs to page the UE via all the beam directions even within one cell. This is commonly referred to as beam sweeping. Furthermore, within a cell, the number of beams can be quite large, e.g., there can be tens or even hundreds of beams. This consumes a large amount of downlink (DL) capacity (i.e., time slots) in which nothing else may be transmitted, and thus the DL overhead can be quite significant.

To alleviate the amount of common paging information transmitted in the cell, one approach may be used where paging is based on a Paging Indicator (PI) instead of paging identity (e.g., SAE temporary mobile subscriber identity (S-TMSI) / international mobile subscriber identity (IMSI)). The PI may be, for example: 1) a specific bit in a bitmap, or 2) Paging Group ID (integer) which is much shorter than the user paging identity (S-TMSI/IMSI). In this paging approach, a group of UEs will monitor the same PI. The UE determines the PI it should monitor during each Paging Occasion (PO) using its paging identity ID (e.g., IMSI, S-TMSI, etc.). If the PI is set/transmitted by the network, all the UEs following the same PI within a cell will send a request to a base station node B (e.g., a node B, eNB, or next generation (NG) node B) to determine whether the paging was directed to them. For this, the UE has to perform an uplink (UL) random access channel (RACH) access and transmit its paging identity to the network. The base station (e.g., NG-NB) compares the received paging identity with the list of paged user identities received from the paging agent, such as a mobility management entity (MME). The base station (e.g., NG-NB) replies with a response only to the UEs that are paged within the group. Fig. 1 illustrates an example diagram of the signalling flow for this paging procedure.

The advantage of the above-outlined approach is that it reduces the downlink signalling overhead by sending a bit/few bits for PI instead of the paging identity (e.g., S-TMSI/IMSI, which can be as large as 64 bits per UE) at the expense of an increase in the UL signalling overhead. This is because all UEs monitoring the same PI will have to perform UL RACH access, although only a subset of the UEs are truly paged (for the purpose of disambiguating each other). Consequently, the probability for UL RACH collision is expected to increase. The RACH collision can occur, for example, if two UEs send the same preamble sequence in the same time resource (same beam direction), i.e., the network would perform UL beam sweeping to receive the UL RACH preambles. The higher the number of UEs performing UL access in the same time resource, the higher the probability of having a RACH collision. Resolving RACH collisions is an expensive and latency prone process.

Since the paging needs to be conveyed to each beam direction in a beamformed system as discussed above, the beam sweeping concept needs to apply. In general, the amount of such beam sweeps for functions like paging should be minimized so as not to waste the system resources and degrade performance. Since the PI based paging allows a high number of Pis to be paged simultaneously and since multiple UEs can be multiplexed under the same PI, the PI based paging needs to be initiated less frequently to be able to page the same amount of UEs compared to paging with explicit UE IDs (such as S-TMSI/IMSI) - LTE maximum is 16 UEs per each PO. However, this further increases the RACH collision probability in a certain time instant. Certain embodiments of the invention provide new methods for alleviating the increase in UL PvACH collision introduced by the use of Pis in paging.

In LTE, the network sends the RACH configuration to the UE as part of system information block (SIB) 2. Fig. 2 illustrates an example of the RACH configuration in SIB 2. The rootSequencelndex shown in Fig. 2 is used by the UE to generate first the Zaddoff Chu sequence (basic sequence, see, e.g., Table 5.7.2-4 in 3GPP technical specification (TS) 36.21 1). Then, the UE can generate the preamble sequence that is actually used for UL access by applying a cyclic shift of the base sequence. In LTE, there are 64 different preamble sequences (cyclic shifts) that can be used by each UE. The cyclic shift interval (i.e., number of samples used in the shift) is determined by a parameter derived from zeroCorrelationZoneConfig and highSpeedFlag (see, e.g., Table 5.7.2-2 in 3GPP TS 36.211).

As depicted in Table 1, the PRACH Configuration Index (prach-Configlndex) parameter indicates the preamble format, System Frame Number (SFN) and subframe number the UE is allowed to send the preamble sequence (see, e.g., Table 5.7.1-2 in 3GPP TS 36.211). For illustration, the first 14 PRACH configuration indices are shown in Table 1 below.

TABLE 1 As shown in Table 1, the preamble format determines the length of the preamble sequence comprised of the sequence part and the cyclic prefix (see, e.g., Table 5.7.1-1 in 3GPP TS 36.211). The SFN and subframe number columns of Table 1 determine the frame and subframe in which the UE can send the preamble sequence. For instance, for PRACH Configuration Index 0, the UE can send the preambles only in the first subframe of even SFN numbers.

The problem with such RACH configuration is that it is applicable for all UEs and in turn does not address properly the problem described above. In other words, the UEs monitoring the different Pis transmitted in a PO will perform UL access according to the same RACH configuration conveyed in SIB 2. As such, it may happen that all UEs would use the nearest UL access opportunity, determined by the SFN and subframe number that are indicated by the RACH configuration, to send their RACH preambles. It may be thought that some of the RACH configurations, such as configuration 14, provide the UE with full flexibility in choosing the SFN and subframe to send the preamble sequence, which will somehow randomize the UL access of different paging groups and lessen the RACH collision. However, such randomization in UL access can never be guaranteed as the decision when to send the preamble sequence is made by each UE individually and depends on its implementation, i.e., it may happen that all UEs use the same nearest UL access opportunity.

According to one embodiment of the invention, the network (e.g., base station, node B, or eNB) configures different RACH configurations for the different UEs monitoring the Pis transmitted in a PO. An advantage of this approach is that the network can configure the UEs monitoring the Pis to perform UL access in different time/frequency resources or using specific Zadoff Chu sequences (basic sequence). This leads to a more balanced UL access and lower the probability for RACH collision. In one embodiment, different sets of UEs monitoring the transmitted Pis may be configured to apply different RACH configurations. For example, in an embodiment, the UEs monitoring the transmitted Pis in a PO can be classified into different sets according to at least one of the following options: (1) the UEs can be classified using their Pis such that all UEs following the same PI belong to the same set and will use the same RACH configuration; or (2) the UEs can be classified using their identities (S-TMSI/IMSI) or categories/types or services rather than their corresponding PI (according to a formula that can be specified). For instance, as one example, each UE can belong to the set S = IMSI mod Y where Y is the number of UE sets, or the set of UEs requiring low- latency access etc. According to option (2), the UEs belonging 5 to the same set can monitor different Pis.

According to one embodiment, the network may configure different time instances (SFN and subframe numbers) and/or frequency resources per UE set or a group of sets for performing UL access. In this case, the different UE sets will perform UL access in different o time/frequency instances, which in turn reduces the number of UEs performing simultaneous

UL access and lowers the probability for RACH collision.

Following the LTE approach, this can be implemented by indicating the prach-Configlndex for each UE set or a group of sets. In LTE, there are 64 possible values for prach-5 Configlndex requiring 6 bits. If there are, for example, 16 UE sets, the number of bits required to indicate the prach-Configlndex of each UE set is 96 bits, which can be quite large to transmit over the radio for systems operating at high carrier frequency. To overcome this issue, one embodiment may include allowing the network to indicate only an index pointing to prach-Configlndex of all possible UE sets. For instance, in an embodiment, the configuration o table illustrated in Fig. 3 can be specified in 3GPP and saved in the UE.

In certain embodiments, the network can indicate the index of the configuration either in a system information or downlink control information (DCI) in physical downlink control channel (PDCCH). In the case where the UE classification is based on the monitored PI, the 5 UE can determine the set it belongs to by checking the order of its PI received in the paging message and apply the corresponding prach-Configlndex. For instance, it may be assumed that the paging message contains only two Pis: 1 and 2. Then, according to the configuration table of Fig. 3, UEs monitoring PI 1 will use the prach-Configlndex of the 1^st UE set column and UE monitoring PI 2 will use prach-Configlndex of the 2^nd UE set column fetched using the0 index configured by the network. In the case where the UE classification is based on other criterion such as user identity (S-TMSI/IMSI), each UE would compute the set that it belongs to according to a specified formula and use the corresponding RACH configuration from the configuration table of Fig. 3. In another embodiment, the network may configure different basic preamble sequence (e.g., Zaddoff Chu sequence) per UE set or a group of sets. In this case, the UE sets may use orthogonal resources for UL access. This may be done by indicating the rootSequencelndex per UE set or a group of sets. In LTE, there are 838 possible values for rootSequencelndex requiring 10 bits. If there are, for example, 16 UE sets, the number of bits required to indicate the rootSequencelndex of each UE set is 160 bits which can be quite large to transmit over the radio. Similar to prach-Configlndex, one embodiment includes indicating, via System Information or DCI in PDCCH, the index pointing to the rootSequencelndex for all possible UE sets. For instance, the configuration table illustrated in Fig. 4 can be specified in 3GPP and saved in the UE.

In yet another embodiment, the RACH configuration for each UE set or a group of sets may depend on the service, type and/or QoS of the paged UEs. For example, if some of the paged UEs in a PO require low access latency, then the RACH configurations of their corresponding UE sets should allow the paged UEs to access the system within an affordable delay budget. Thus, if the UE sets are derived based on PI, the network may have to arrange the order the Pis that shall be sent in the paging message such that the paged UEs use the corresponding appropriate RACH configurations indicated in the table.

According to another embodiment of the invention, the UEs monitoring the Pis transmitted in a PO may select randomly the time/frequency resource for UL access following the main RACH configuration of the cell. For example, in this embodiment, the UEs paged with Pis may follow the main RACH configuration of the cell (e.g., determining the basic sequence, SFN and subframe numbers the UE can send their RACH preamble, possible frequency resources), but may select the PRACH preamble resource randomly from both time and frequency domain RACH resources (in contrast to the next RACH opportunity). Alternatively, the "main RACH configuration" could be RACH configuration dedicated for paging operation. In one embodiment, the network may configure a maximum time duration/amount of RACH cycles/etc. during which the UE shall attempt to access the cell. This configuration may be common in the cell or UE specific or both methods can be applied. The maximum time duration may also depend on the service type. The maximum time duration may be subject to the dedicated paging cycle of the UE or default UE paging cycle configured by the cell. In another embodiment, the network may configure time windows during which the UE shall attempt to access the cell. The time window may be PI or PI group specific. The time window location relative to the paging subframe may be dependent on the service/access classes of the UE.

In another embodiment, the network may dynamically enable or disable the use of such dedicated RACH configuration per UE set or randomly selected time/frequency RACH resources from the main RACH configuration of the cell. For instance, if the number of Pis transmitted in a PO is high, the network may enable the use of dedicated/randomly selected RACH configurations/resources. On the other hand, if the number of Pis transmitted is low the network may disable the use of dedicated/randomly selected RACH configurations/resources. In this case, the UE would fall back to the use the default RACH configuration. As one example, this enable/disable feature may be implemented, for instance, by a Boolean flag indicating whether dedicated/randomly selected RACH configurations/resources are used or default configuration applies.

Fig. 5a illustrates an example of an apparatus 10 according to an embodiment. In an embodiment, apparatus 10 may be a node, host, or server in a communications network or serving such a network. For example, apparatus 10 may be a base station, a node B, an evolved node B, 5G node B or access point, next generation node B (NG-NB), WLAN access point, mobility management entity (MME), or subscription server associated with a radio access network, such as a GSM network, LTE network or 5G radio access technology. It should be noted that one of ordinary skill in the art would understand that apparatus 10 may include components or features not shown in Fig. 5a.

As illustrated in Fig. 5 a, apparatus 10 may include a processor 12 for processing information and executing instructions or operations. Processor 12 may be any type of general or specific purpose processor. While a single processor 12 is shown in Fig. 5 a, multiple processors may be utilized according to other embodiments. In fact, processor 12 may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, as examples. Processor 12 may perform functions associated with the operation of apparatus 10 which may include, for example, precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatus 10, including processes related to management of communication resources.

Apparatus 10 may further include or be coupled to a memory 14 (internal or external), which may be coupled to processor 12, for storing information and instructions that may be executed by processor 12. Memory 14 may be one or more memories and of any type suitable to the local application environment, and may be implemented using any suitable volatile or nonvolatile data storage technology such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and removable memory. For example, memory 14 can be comprised of any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, hard disk drive (HDD), or any other type of non-transitory machine or computer readable media. The instructions stored in memory 14 may include program instructions or computer program code that, when executed by processor 12, enable the apparatus 10 to perform tasks as described herein. In some embodiments, apparatus 10 may also include or be coupled to one or more antennas 15 for transmitting and receiving signals and/or data to and from apparatus 10. Apparatus 10 may further include or be coupled to a transceiver 18 configured to transmit and receive information. The transceiver 18 may include, for example, a plurality of radio interfaces that may be coupled to the antenna(s) 15. The radio interfaces may correspond to a plurality of radio access technologies including one or more of GSM, NB-IoT, LTE, 5G, WLAN, Bluetooth, BT-LE, NFC, radio frequency identifier (RPID), ultrawideband (UWB), and the like. The radio interface may include components, such as filters, converters (for example, digital-to-analog converters and the like), mappers, a Fast Fourier Transform (FFT) module, and the like, to generate symbols for a transmission via one or more downlinks and to receive symbols (for example, via an uplink). As such, transceiver 18 may be configured to modulate information on to a carrier waveform for transmission by the antenna(s) 15 and demodulate information received via the antenna(s) 15 for further processing by other elements of apparatus 10. In other embodiments, transceiver 18 may be capable of transmitting and receiving signals or data directly.

In an embodiment, memory 14 may store software modules that provide functionality when executed by processor 12. The modules may include, for example, an operating system that provides operating system functionality for apparatus 10. The memory may also store one or more functional modules, such as an application or program, to provide additional functionality for apparatus 10. The components of apparatus 10 may be implemented in hardware, or as any suitable combination of hardware and software.

In one embodiment, apparatus 10 may be a network node or server, such as a base station, node B, eNB, 5G node B or access point, or next generation node B (NG-NB), for example. According to certain embodiments, apparatus 10 may be controlled by memory 14 and processor 12 to perform the functions associated with embodiments described herein. For example, in an embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure one or more UEs monitoring the Pis transmitted in a PO to use different RACH configurations.

For example, in one embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to classify one or more UEs that are monitoring the Pis transmitted in a PO into different sets of UEs, and to configure the UEs within the same set to apply the same RACH configuration and/or each of the sets of UEs to apply different RACH configurations. In an embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure different time instances and/or frequency resources per set of UEs or group of sets for performing UL access.

In one embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to classify the UEs according to their Pis such that all UEs following the same PI belong to the same set and use the same RACH configuration. In another embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to classify the UEs according to their identities (e.g., S-TMSI/IMSI), their categories, types, and/or services. According to an embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure the sets of UEs by configuring different time instances and/or frequency resources per set of UEs or a group of sets of UEs for performing UL access. In one embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure the sets of UEs by indicating the PRACH configuration index for each set of UEs or group of sets. According to one example embodiment, apparatus 10 may be controlled by 5 memory 14 and processor 12 to indicate just an index pointing to the PRACH configuration index of all possible UE sets. For example, in an embodiment, the index of the configuration may be indicated in a system information or DCI in PDCCH.

In another embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to o configure the sets of UEs by configuring different basic preamble sequence (e.g., Zaddoff Chu sequence) per set of UEs or group of sets. According to an example embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to indicate the root sequence index per set of UEs or group of sets. For instance, in an embodiment, the index pointing to the root sequence index may be indicated in a system information or DCI in PDCCH for all possible5 sets of UEs.

According to another embodiment, the RACH configuration for each set of UEs or group of sets may depend upon the service, type, and/or QoS of the paged UEs. For example, in this embodiment, if some of the paged UEs in a PO require low access latency, then the RACH o configuration(s) of their corresponding UE set(s) should allow the paged UEs to access the system within an affordable delay budget.

In another embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure one or more UEs monitoring the Pis transmitted in a PO to use different RACH 5 configurations by configuring the main RACH configuration and then having the UEs decide on which resource to send the PRACH preamble following the main RACH configuration. According to an embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure a maximum time duration or amount of RACH cycles during which a UE shall attempt to access the cell. This configuration may be common in the cell or UE specific or0 both methods can be applied. The maximum time duration may depend on the service type, and/or may be subject to the dedicated paging cycle of the UE or default UE paging cycle configured by the cell. In another embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure time windows during which a UE shall attempt to access the cell. The time window may be PI or PI group specific. The time window location relative to the paging sub frame may be dependent on the service/access classes of the UE.

In a further embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to dynamically enable/disable the use of a dedicated RACH configuration per set of UEs, or to dynamically enable/disable the randomly selected time/frequency RACH resources from the main RACH configuration of the cell. For instance, if the number of Pis transmitted in a PO is high, apparatus 10 may enable the use of dedicated/randomly selected RACH configurations/resources. On the other hand, if the number of Pis transmitted is low, apparatus 10 may disable the use of dedicated/randomly selected RACH configurations/resources. In this case, the UE would fall back to the use of the default RACH configuration. In an embodiment, this enable/disable feature can be implemented by a Boolean flag indicating whether dedicated/randomly selected RACH configurations/resources are used or default configuration applies.

Fig. 5b illustrates an example of an apparatus 20 according to another embodiment. In an embodiment, apparatus 20 may be a node or element in a communications network or associated with such a network, such as a UE, mobile equipment (ME), mobile station, mobile device, stationary device, IoT device, or other device. As described herein, UE may alternatively be referred to as, for example, a mobile station, mobile equipment, mobile unit, mobile device, user device, subscriber station, wireless terminal, tablet, smart phone, IoT device or NB-IoT device, or the like. As one example, Apparatus 20 may be implemented in, for instance, a wireless handheld device, a wireless plug-in accessory, or the like. In some example embodiments, apparatus 20 may include one or more processors, one or more computer-readable storage medium (for example, memory, storage, and the like), one or more radio access components (for example, a modem, a transceiver, and the like), and/or a user interface. In some embodiments, apparatus 20 may be configured to operate using one or more radio access technologies, such as GSM, NB-IoT, LTE, LTE-A, 5G, WLAN, WiFi, Bluetooth, NFC, and any other radio access technologies. It should be noted that one of ordinary skill in the art would understand that apparatus 20 may include components or features not shown in Fig. 5b. As illustrated in Fig. 5b, apparatus 20 may include or be coupled to a processor 22 for processing information and executing instructions or operations. Processor 22 may be any type of general or specific purpose processor. While a single processor 22 is shown in Fig. 5b, multiple processors may be utilized according to other embodiments. In fact, processor 22 may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, as examples.

Processor 22 may perform functions associated with the operation of apparatus 20 including, without limitation, precoding of antenna gain/phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatus 20, including processes related to management of communication resources.

Apparatus 20 may further include or be coupled to a memory 24 (internal or external), which may be coupled to processor 22, for storing information and instructions that may be executed by processor 22. Memory 24 may be one or more memories and of any type suitable to the local application environment, and may be implemented using any suitable volatile or nonvolatile data storage technology such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and removable memory. For example, memory 24 can be comprised of any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, or any other type of non-transitory machine or computer readable media. The instructions stored in memory 24 may include program instructions or computer program code that, when executed by processor 22, enable the apparatus 20 to perform tasks as described herein.

In some embodiments, apparatus 20 may also include or be coupled to one or more antennas 25 for receiving a downlink signal and for transmitting via an uplink from apparatus 20. Apparatus 20 may further include a transceiver 28 configured to transmit and receive information. The transceiver 28 may also include a radio interface (e.g., a modem) coupled to the antenna 25. The radio interface may correspond to a plurality of radio access technologies including one or more of GSM, NB-IoT, LTE, LTE-A, 5G, WLAN, Bluetooth, BT-LE, NFC, RFID, UWB, and the like. The radio interface may include other components, such as filters, converters (for example, digital-to-analog converters and the like), symbol demappers, signal shaping components, an Inverse Fast Fourier Transform (IFFT) module, and the like, to process symbols, such as OFDMA symbols, carried by a downlink or an uplink.

For instance, transceiver 28 may be configured to modulate information on to a carrier waveform for transmission by the antenna(s) 25 and demodulate information received via the antenna(s) 25 for further processing by other elements of apparatus 20. In other embodiments, transceiver 28 may be capable of transmitting and receiving signals or data directly. Apparatus 20 may further include a user interface, such as a graphical user interface or touchscreen.

In an embodiment, memory 24 stores software modules that provide functionality when executed by processor 22. The modules may include, for example, an operating system that provides operating system functionality for apparatus 20. The memory may also store one or more functional modules, such as an application or program, to provide additional functionality for apparatus 20. The components of apparatus 20 may be implemented in hardware, or as any suitable combination of hardware and software.

According to one embodiment, apparatus 20 may be a UE, mobile device, mobile station, ME, IoT device and/or NB-IoT device, for example. According to certain embodiments, apparatus 20 may be controlled by memory 24 and processor 22 to perform the functions associated with embodiments described herein. According to an embodiment, apparatus 20 may be classified by the network into a set or group of UEs. Apparatus 20 may then be configured by the network to apply a RACH configuration according to the set of UEs it is classified in. According to an embodiment, apparatus 10 may be classified according to its PI such that all UEs following the same PI belong to the same set and therefore use the same RACH configuration. In another embodiment, apparatus 10 may be classified according to its identity (e.g., S-TMSI/IMSI) or categories or types of services.

In one embodiment, apparatus 20 may be controlled by memory 24 and processor 22 to receive an indication from the network of a PRACH configuration index or an index pointing to PRACH configuration index of all possible UE sets. The indication of the index of the configuration may be received either in a system information or DCI in PDCCH, for example. In the case where the UE set is based on the monitored PI, apparatus 20 may be controlled by memory 24 and processor 22 to determine the set it belongs to by checking the order of its PI received in the paging message and to apply the corresponding prach-Configlndex. In the case where the UE set is based on user identity (e.g., S-TMSI/IMSI), apparatus 20 may be controlled by memory 24 and processor 22 to compute the set that it belongs to according to a specified formula and use the corresponding RACH configuration from a configuration table, such as the table illustrated in Fig. 3. In another embodiment, apparatus 20 may be configured with a basic preamble sequence (e.g., Zadoff Chu sequence) according to the set it is classified in. In this case, apparatus 20 may be controlled by memory 24 and processor 22 to use orthogonal resources for UL access. In this embodiment, apparatus 20 may be controlled by memory 24 and processor 22 to receive an indication from the network of a root sequence index or an index pointing to the root sequence index for all possible sets of UEs. Apparatus 20 may then be controlled by memory 24 and processor 22 to compute the set that it belongs to according to a specified formula and use the corresponding RACH configuration from a configuration table, such as the table illustrated in Fig. 4. In yet another embodiment, apparatus 20, which is monitoring the Pis transmitted in a PO, may be controlled by memory 24 and processor 22 to select randomly the time or frequency resource for UL access following the main RACH configuration of the cell. Thus, in this embodiment, apparatus 20 may be controlled by memory 24 and processor 22 to follow the main RACH of its cell, but to select the PRACH preamble resource randomly from both time and frequency domain RACH resources. In an embodiment, "the main RACH configuration of the cell" refers to the RACH configuration dedicated for paging operation. According to one embodiment, the network may configure a maximum time duration or amount of RACH cycles during which apparatus 20 may attempt to access the cell. This configuration may be common in the cell or specific to apparatus 20 or both. The maximum time duration may depend on the service type, and/or may be subject to the dedicated paging cycle of apparatus 20 or default paging cycle configured by the cell. In another embodiment, the network may configure time windows during which apparatus 20 may attempt to access the cell. The time window may be PI or PI group specific. The time window location relative to the paging subframe may be dependent on the service/access classes of apparatus 20.

Fig. 6 illustrates an example flow diagram of a method, according to one embodiment. In an embodiment, the method of Fig. 6 may be performed by a network node, such as a base station, node B, eNB, or NG-NB, for example. As illustrated in the example of Fig. 6, the method may include, at 600, configuring one or more UEs monitoring the Pis transmitted in a PO to use different RACH configurations. In one embodiment, the configuring may include classifying the one or more UEs, which are monitoring Pis transmitted in a PO, into different sets of UEs, and configuring the UEs within the same set to apply the same RACH configuration and/or each of the sets of UEs to apply different RACH configurations. In an embodiment, the configuring may include configuring different time instances and/or frequency resources per set of UEs or group of sets for performing UL access. In one embodiment, the classifying may include classifying the UEs according to their Pis such that all UEs following the same PI belong to the same set and use the same RACH configuration. In another embodiment, the classifying may include classifying the UEs according to their identities (e.g., S-TMSI/IMSI), their categories, types, and/or services. According to an embodiment, the configuring may include configuring different time instances and/or frequency resources per set of UEs or a group of sets of UEs for performing UL access.

In one embodiment, the configuring may include indicating the PRACH configuration index for each set of UEs or group of sets. According to one example embodiment, the configuring may further include indicating just an index pointing to the PRACH configuration index of all possible UE sets. For example, in an embodiment, the index of the configuration may be indicated in a system information or DCI in PDCCH.

In another embodiment, the configuring may include configuring different basic preamble sequence (e.g., Zaddoff Chu sequence) per set of UEs or group of sets. According to an example embodiment, the configuring may further include indicating the root sequence index per set of UEs or group of sets. For instance, in an embodiment, the index pointing to the root sequence index may be indicated in a system information or DCI in PDCCH for all possible sets of UEs. According to another embodiment, the RACH configuration for each set of UEs or group of sets may depend upon the service, type, and/or QoS of the paged UEs. For example, in this embodiment, if some of the paged UEs in a PO require low access latency, then the RACH configuration(s) of their corresponding UE set(s) should allow the paged UEs to access the system within an affordable delay budget.

According to another embodiment, the configuring may include configuring the main RACH configuration and then having the UEs decide on which resource to send the PRACH preamble following the main RACH configuration. In an embodiment, the configuring may include configuring a maximum time duration or amount of RACH cycles during which a UE shall attempt to access the cell. This configuration may be common in the cell or UE specific or both methods can be applied. The maximum time duration may depend on the service type, and/or may be subject to the dedicated paging cycle of the UE or default UE paging cycle configured by the cell. In another embodiment, the configuring may include configuring time windows during which a UE shall attempt to access the cell. The time window may be PI or PI group specific. The time window location relative to the paging subframe may be dependent on the service/access classes of the UE. In a further embodiment, the method may also include dynamically enabling/disabling the use of a dedicated RACH configuration per set of UEs, or dynamically enabling/disabling the randomly selected time/frequency RACH resources from the main RACH configuration of the cell. For instance, if the number of Pis transmitted in a PO is high, the dynamically enabling/disabling may include enabling the use of dedicated/randomly selected RACH configurations/resources. On the other hand, if the number of Pis transmitted is low, the dynamically enabling/disabling may include disabling the use of dedicated/randomly selected RACH configurations/resources. In this case, the UE would fall back to the use of the default RACH configuration. In an embodiment, the enabling/disabling may include incorporating a Boolean flag indicating whether dedicated/randomly selected RACH configurations/resources are used or default configuration applies.

It is noted that, while embodiments of the invention discussed in the foregoing refer to implementations in LTE, other embodiments of the invention are also applicable in other radio access technologies, such as 5G, NR, or any other future radio access network. In view of the above, embodiments of the invention provide several technical improvements and/or advantages. For example, as a result of certain embodiments, improved link level performance can be achieved. As such, embodiments of the invention can improve performance and throughput of network nodes including, for example, base stations/eNBs and UEs. Accordingly, the use of embodiments of the invention result in improved functioning of communications networks and their nodes.

In some embodiments, the functionality of any of the methods, processes, signaling diagrams, or flow charts described herein may be implemented by software and/or computer program code or portions of code stored in memory or other computer readable or tangible media, and executed by a processor.

In certain embodiments, an apparatus may be included or be associated with at least one software application, module, unit or entity configured as arithmetic operation(s), or as a program or portions of it (including an added or updated software routine), executed by at least one operation processor. Programs, also called program products or computer programs, including software routines, applets and macros, may be stored in any apparatus-readable data storage medium and include program instructions to perform particular tasks.

A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it. Modifications and configurations required for implementing functionality of an embodiment may be performed as routine(s), which may be implemented as added or updated software routine(s). Software routine(s) may be downloaded into the apparatus.

Software or a computer program code or portions of it may be in a source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers. The computer readable medium or computer readable storage medium may be a non-transitory medium.

In other embodiments, the functionality may be performed by hardware, for example through the use of an application specific integrated circuit (ASIC), a programmable gate array (PGA), a field programmable gate array (FPGA), or any other combination of hardware and software. In yet another embodiment, the functionality may be implemented as a signal, a non-tangible means that can be carried by an electromagnetic signal downloaded from the Internet or other network.

According to an embodiment, an apparatus, such as a node, device, or a corresponding component, may be configured as a computer or a microprocessor, such as single-chip computer element, or as a chipset, including at least a memory for providing storage capacity used for arithmetic operation and an operation processor for executing the arithmetic operation.

One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.

Claims

Claims:

1. A method, comprising:

configuring, by a network node, one or more user equipment monitoring paging 5 indicators (Pis) transmitted in a paging occasion (PO) to use different random access channel (RACH) configurations.

2. The method according to claim 1, wherein the configuring comprises classifying the one or more user equipment that are monitoring the paging indicator (Pis) transmitted in the paging o occasion (PO) into different sets of UEs.

3. The method according to claim 2, wherein the classifying further comprises classifying the one or more user equipment according to their identities, their categories, types, and/or services.

5

4. The method according to claims 2 or 3, the method further comprising configuring the user equipment within a same set to apply a same random access channel (RACH) configuration, and/or configuring each of the sets of user equipment to apply different random access channel (RACH) configurations.

0

5. The method according to any one of claims 1-4, wherein the configuring of the one or more user equipment to use different random access channel (RACH) configurations comprises configuring a main random access channel (RACH) configuration and then allowing the one or more user equipment to decide on which resource to send a physical random access channel 5 (PRACH) preamble following the main random access channel (RACH) configuration.

6. The method according to any one of claims 1-5, further comprising:

configuring a maximum time duration or amount of random access channel (RACH) cycles during which the one or more user equipment attempt to access a cell, wherein the 0 maximum time duration or amount of random access channel (RACH) cycles is common in the cell or user equipment-specific or both.

7. The method according to any one of claims 1-6, further comprising: dynamically enabling or disabling use of a dedicated random access channel (RACH) configuration per set of user equipment, or

dynamically enabling or disabling the randomly selected time/frequency random access channel (RACH) resources from the main random access channel (RACH) configuration of the cell.

8. An apparatus, comprising:

configuring means for configuring one or more user equipment monitoring paging indicators (Pis) transmitted in a paging occasion (PO) to use different random access channel (RACH) configurations.

9. The apparatus according to claim 8, wherein the configuring means comprises classifying means for classifying the one or more user equipment that are monitoring the paging indicator (Pis) transmitted in the paging occasion (PO) into different sets of UEs.

10. The apparatus according to claim 9, wherein the classifying means further comprises means for classifying the one or more user equipment according to their identities, their categories, types, and/or services.

11. The apparatus according to claims 9 or 10, the apparatus further comprising configuring means for configuring the user equipment within a same set to apply a same random access channel (RACH) configuration, and/or configuring means for configuring each of the sets of user equipment to apply different random access channel (RACH) configurations.

12. The apparatus according to any one of claims 8-11, wherein the configuring means for configuring of the one or more user equipment to use different random access channel (RACH) configurations further comprises means for configuring a main random access channel (RACH) configuration and then allowing the one or more user equipment to decide on which resource to send a physical random access channel (PRACH) preamble following the main random access channel (RACH) configuration.

13. The apparatus according to any one of claims 8-12, further comprising: configuring means for configuring a maximum time duration or amount of random access channel (RACH) cycles during which the one or more user equipment attempt to access a cell, wherein the maximum time duration or amount of random access channel (RACH) cycles is common in the cell or user equipment-specific or both.

14. The apparatus according to any one of claims 8-13, further comprising:

means for dynamically enabling or disabling use of a dedicated random access channel (RACH) configuration per set of user equipment, or

means for dynamically enabling or disabling the randomly selected time/frequency random access channel (RACH) resources from the main random access channel (RACH) configuration of the cell.

15. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus at least to

configure one or more user equipment monitoring paging indicators (Pis) transmitted in a paging occasion (PO) to use different random access channel (RACH) configurations.

16. A method, comprising:

receiving, by a user equipment, an indication from a network of a physical random access channel (PRACH) configuration index or an index pointing to a physical random access channel (PRACH) configuration index of all possible user equipment sets,

wherein the user equipment is classified into a set of user equipment.

17. The method according to claim 16, wherein the receiving comprises receiving the indication of the index of the configuration in a system information or in downlink control information (DCI).

18. The method according to claims 16 or 17,

wherein, when the set of user equipment is based on the monitored paging indicator (PI), the method comprises determining the set that the user equipment belongs to by checking an order of its paging indicator (PI) received in the paging message and applying a corresponding prach-Configlndex; and

wherein, when the set of user equipment is based on user equipment identity, the method comprises computing the set that the user equipment belongs to according to a specified formula and using a corresponding random access channel (RACH) configuration from a configuration table.

19. An apparatus, comprising:

receiving means for receiving an indication from a network of a physical random access channel (PRACH) configuration index or an index pointing to a physical random access channel (PRACH) configuration index of all possible user equipment sets,

wherein the apparatus is classified into a set of user equipment.

20. The apparatus according to claim 19, wherein the receiving means comprises means for receiving the indication of the index of the configuration in a system information or in downlink control information (DCI).

21. The apparatus according to claims 19 or 20,

wherein, when the set of user equipment is based on the monitored paging indicator (PI), the apparatus comprises determining means for determining the set that the apparatus belongs to by checking an order of its paging indicator (PI) received in the paging message and applying a corresponding prach-Configlndex; and

wherein, when the set of user equipment is based on user equipment identity, the apparatus comprises computing means for computing the set that the apparatus belongs to according to a specified formula and using a corresponding random access channel (RACH) configuration from a configuration table.

22. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

receive an indication from a network of a physical random access channel (PRACH) configuration index or an index pointing w a physical random access channel (PRACH) configuration index of all possible user equipment sets,

wherein the apparatus is classified into a set of user equipment.

23. A computer program, embodied on a non-transitory computer readable medium, wherein the computer program is configured to control a processor to perform a process according to any one of claims 1-7 or 16-18.