CN108307476B

CN108307476B - Method and device for initial access of terminal device in wireless access network

Info

Publication number: CN108307476B
Application number: CN201710026188.0A
Authority: CN
Inventors: 李栋
Original assignee: Nokia Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2017-01-13
Filing date: 2017-01-13
Publication date: 2021-04-06
Anticipated expiration: 2037-01-13
Also published as: CN108307476A

Abstract

The present disclosure presents methods and devices for initial access of a terminal device in a Radio Access Network (RAN). In the present disclosure, a two-layer structure of discovery signal transmission is proposed. The first discovery signal includes a synchronization signal and necessary system information, and is periodically transmitted at a first period. The second discovery signal includes a transmission point-specific beam reference signal or a transmission point-specific synchronization signal and necessary system information, and is periodically transmitted at a second periodicity. The first discovery signal indicates resource configuration information of the second discovery signal.

Description

Method and device for initial access of terminal device in wireless access network

Technical Field

Embodiments of the present disclosure relate to radio access networks, and more particularly, to methods, devices and computer program products for initial access by a terminal device in a Radio Access Network (RAN).

Background

The dramatic increase in mobile data places higher demands on the capacity of communication systems, and the densification of wireless networks has become an important way to meet the demand for mobile data. In the discussion of the third generation partnership project 3GPP RAN2 regarding the new air interface (NR) of the fifth generation 5G mobile communication system, agreement has been reached to include one or more transmission points in a cell. The design of cells with multiple transmission points may provide advantages in mobility management, coordinated transmission, interference control. In the operation of the 5G mobile communication system, since the carriers used include low frequency carriers such as below 6GHz and high frequency carriers such as 6-100GHz, a general framework needs to be considered in designing a technical solution for initially accessing a network by a terminal device to support the diversity requirement described above.

Disclosure of Invention

Embodiments of the present disclosure provide methods, apparatuses, and computer program products for initial access of a terminal device in a radio access network, RAN.

According to a first aspect of the present disclosure, a method in a radio access network, RAN, for initial access of a terminal device is provided. There are multiple transmission points in a cell in the RAN. A first discovery signal associated with a cell in the RAN is transmitted at a first transmission point of the plurality of transmission points with a first periodicity in synchronization with a second transmission point of the plurality of transmission points. At the first transmission point, a second discovery signal associated with the first transmission point is transmitted at a second periodicity. The first discovery signal indicates resource configuration information of the second discovery signal.

According to a second aspect of the present disclosure, there is provided a transmission point in a Radio Access Network (RAN), a cell in the RAN having the transmission point and at least one other transmission point. The transmission point includes a controller and a memory including instructions. The instructions, when executed by the controller, cause the transmission point to perform actions. The actions performed include: transmitting, at the transmission point, a first discovery signal associated with a cell in the RAN at a first periodicity in synchronization with at least one other transmission point; and transmitting, at the transmission point, a second discovery signal associated with the transmission point at a second periodicity, the first discovery signal indicating resource configuration information of the second discovery signal.

According to a third aspect of the disclosure, there is provided a program product, tangibly stored on a non-transitory computer-readable medium and comprising machine executable instructions that, when executed by a computer, cause the computer to perform the above method.

It should be understood that the statements herein reciting aspects are not intended to limit the critical or essential features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings. In the drawings, like reference numerals generally refer to like parts.

Fig. 1 shows a schematic diagram of a radio access network according to an embodiment of the present disclosure;

FIG. 2A shows a flow diagram of a method according to an embodiment of the present disclosure;

FIG. 2B shows a flow diagram of a method according to another embodiment of the present disclosure;

fig. 3 illustrates a block diagram of a discovery signal according to an embodiment of the present disclosure;

fig. 4 illustrates a block diagram of a discovery signal according to another embodiment of the present disclosure;

fig. 5 illustrates a structure diagram of a discovery signal according to yet another embodiment of the present disclosure;

FIG. 6 shows a block diagram of an apparatus according to an embodiment of the present disclosure; and

fig. 7 illustrates a block diagram of an apparatus in accordance with certain embodiments of the present disclosure.

Detailed Description

The principles and spirit of the present disclosure will be described with reference to a number of exemplary embodiments shown in the drawings. It is understood that these specific embodiments are described merely to enable those skilled in the art to better understand and implement the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

The term "base station" as used herein refers to a conventional base station, such as a node B (NodeB or NB), a Base Transceiver Station (BTS), a Base Station (BS), or a base station subsystem (BSs), etc. The term "transmission point" as used herein refers to a low power transmission node or the like having radio frequency transceiving functionality and optionally partial baseband processing functionality.

The term "terminal equipment" refers to any terminal equipment TE capable of communicating with a base station. The terminal device may be a user equipment UE, or any terminal with wireless communication function, including but not limited to a mobile phone, a computer, a personal digital assistant, a game console, a wearable device, a sensor, and so on. The term TE can be used interchangeably with mobile station, subscriber station, mobile terminal, user equipment, terminal equipment, wireless device, etc.

For the sake of discussion, an eNB is taken as an example of a base station, which is also referred to as a network device herein, and one or more transmission points distributed in a cell corresponding to the eNB are referred to as a transmission node, and the transmission node has a radio frequency transceiving function and optionally a partial baseband processing function. In other words, the terms "eNB" and "network device", "base station" may be used interchangeably in the context of the present disclosure, the terms "transmission point", "transmission node", "TP", "TRP" may be used interchangeably, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably. It should be understood that this is merely exemplary and is not intended to limit the scope of applicability of the present disclosure in any way.

As described above, the increase of mobile data puts higher demands on the capacity of a communication system, and the densification of wireless networks becomes an important way to meet the demand of mobile data. In the discussion of the third generation partnership project 3GPP RAN2 regarding the new air interface (NR) of the fifth generation 5G mobile communication system, agreement has been reached to include one or more transmission points in a cell. The design of cells with multiple transmission points may provide advantages in mobility management, coordinated transmission, interference control. In the operation of the 5G mobile communication system, since the carriers used include low frequency carriers such as below 6GHz and high frequency carriers such as 6-100GHz, a general framework needs to be considered in designing a technical solution for initially accessing a network by a terminal device to support the diversity requirement described above. In the design of the initial access framework, the design of the discovery signal becomes an important issue to be solved.

In the present disclosure, a two-layer architecture for discovery signal transmission is presented. The first discovery signal includes a synchronization signal and necessary system information, and is periodically transmitted at a first period. The second discovery signal includes a transmission point-specific beam reference signal or a transmission point-specific synchronization signal and necessary system information, and is periodically transmitted at a second periodicity. The first discovery signal indicates resource configuration information of the second discovery signal. In order to achieve reliable coverage, the first layer discovery signal is transmitted by all or part of the transmission points in the cell synchronously in the same time-frequency resource in a single frequency network manner by using increased transmission power or wider beam width. To overcome the large path loss and blocking at high frequencies, the second layer discovery signal is transmitted by the associated transmission point using a beam sweep having a lower power narrower beamwidth.

Fig. 1 shows a schematic diagram of a radio access network RAN 100 in which embodiments of the present disclosure may be implemented. In fig. 1, the coverage of the network devices 102 in the RAN 100 forms a cell 108. Network device 102 may or may not have radio functionality, in which case the radio functionality is performed entirely by transmission point 104. One non-limiting example of a network device 102 with wireless transceiving functionality is an eNB. Without wireless transceiving functionality, the network device 102 may act as a central processing point to process data associated with the transmission point 104. A plurality of transmission points, such as a first transmission point 104-1 and a second transmission point 104-2 (collectively referred to as "transmission points 104"), are densely deployed in the cell 108.

The network device 102 and the transmission point 104 are capable of serving a plurality of terminal devices 106 in a cell 108. In the case where network device 102 has wireless transceiving functionality, network device 102 provides coverage for signal and control channels for all terminal devices 106, while transmission point 104 provides a data channel for a particular terminal device 106. In the case where the network device 102 does not have wireless transceiving functionality, coverage for signal and control channels as well as data channels are provided by the transmission point 104 for a particular terminal device 106. It should be understood that the types of channels provided by network device 102 and transmission point 104 described herein are exemplary only and not limiting. In some embodiments, end device 106 is capable of connecting to network device 102 and transmission point 104-1 simultaneously. Wired or wireless communication connections may be made between network device 102 and transmission points 104 and between transmission points 104.

In order to achieve initial access of the terminal device 106 to the radio network RAN 100, a discovery signal needs to be provided. The discovery signal may be provided by the transmission point 104. All or some of the transmission points 104 may transmit discovery signals associated with the cells 108 so that the terminal devices 106 may connect to the cells 108. The transmission point 104-1 also transmits a discovery signal specific to itself so that the base station knows which beam of the transmission point 104-1 the terminal device 106 is in the vicinity of the transmission point 104-1 and covered by means of the feedback of the terminal device based on the transmission point specific discovery signal so that subsequent data transmission to the terminal device can be done by the transmission point through the selected beam.

Fig. 2A shows a flow diagram of a method 200A for initial access for a terminal device 106 in a radio access network RAN 100 according to an embodiment of the present disclosure. In some embodiments, method 200A may be performed by any one of a plurality of transmission points. For convenience of description, the first transmission point 104-1 will be described as the execution subject of the method 200A. It should be understood that the method 200A may also include additional steps not shown and/or may omit steps shown. The scope of the subject matter described herein is not limited in this respect.

At 202, at a first transmission point 104-1, a first discovery signal associated with a cell 108 in the RAN 100 is transmitted with a first periodicity 310 in synchronization with a second transmission point 104-2 of the plurality of transmission points 104.

As described above, in embodiments of the present disclosure, all or some of the transmission points 104 may transmit discovery signals associated with the cells 108 so that the terminal devices 106 may connect to the cells 108. That is, the first transmission point 104-1 may transmit the first discovery signal with a plurality of other transmission points 104. In some embodiments, the time-frequency resource occupied by the first discovery signal may be predefined by the system. Reliable coverage in cell 108 may be achieved by transmitting the first discovery signal by transmission point 104-1 and other transmission points 104.

At 204, a second discovery signal associated with the first transmission point 104-1 is transmitted at a second periodicity 312. In particular, according to an embodiment of the present disclosure, resource configuration information of the second discovery signal is indicated in the first discovery signal. By indicating the time-frequency resources occupied by the second discovery signal by the first discovery signal, the flexibility of the system can be improved. Specifically, in the case that the radio frequency implementation used by different transmission points 104 is different, different resource configuration manners need to be set for the transmission points 104. After receiving the first discovery signal, the terminal device 106 may acquire the resource configuration of the second discovery signal, so that the second discovery signal is received more easily.

In addition to achieving synchronization and acquiring the necessary system information, the second discovery signal may also be used to support beam scanning, beam alignment, or beam tracking between the transmission point 104-1 and the terminal devices 106 within its coverage area. Example implementations of the first discovery signal and the second discovery signal are described in detail below in conjunction with fig. 3 and 4.

In some embodiments, the first discovery signal carries cell 108 specific information including at least a cell identification, a partial system message, and resource configuration information of the second discovery signal, and the second discovery signal carries first transmission point 104-1 specific information including at least identification information of the first transmission point 104-1 and beam information used by the first transmission point 104-1.

In some embodiments, the first period 310 is relatively large and optionally an integer multiple of the second period 312. For example, the first period 310 may be 100ms, while the second period 312 is 10 ms. Optionally, in some embodiments, the transmission instants of the second discovery signal may be evenly distributed in the first period 310. Setting the second periodicity 312 shorter facilitates the terminal device 106 in determining the best beam available in a timely manner. For example, in the case of using the millimeter wave band, the path loss and the blocking have a great influence on the transmission of signals. Particularly during movement of the terminal device 106, the best transmission beam available to the terminal device 106 is also changing, and a shorter transmission period of the second discovery signal may make the adjustment of the beam used between the transmission point 104 and the terminal device 106 more timely.

In some embodiments, to achieve reliable coverage, the first layer discovery signal is transmitted by all or some of the transmission points 104 in the cell 108 in a single frequency network manner synchronously at the same time-frequency resource using increased transmission power or wider beamwidth. To overcome the large path loss and blocking at high frequencies, the second layer discovery signal is transmitted by the associated transmission point 104-1 using a beam sweep having a lower power narrower beamwidth.

Fig. 2B shows a flow diagram of a method 200B for initial access for a terminal device 106 in a radio access network RAN 100 according to an embodiment of the present disclosure. The method 200B may be considered an exemplary implementation of the method 200A, with the addition of step 206 and step 210 to the method 200A.

Generally, in the method 200B, two modes of the second discovery signal are designed: an active mode and an inactive mode. In the active mode, Synchronization Signals (SS)302 in the first layer discovery signal specific to cell 108 and essential system messages (ESI)304 in the first layer discovery signal, as well as a second discovery signal specific to transmission point 104-1, are transmitted periodically. In the inactive mode, only the SS 302 in the first layer discovery signal and the ESI 304 in the first layer discovery signal specific to the cell 108 are periodically transmitted while the second discovery signal ceases transmission. The two modes can be switched to each other depending on specific conditions. The inactive mode and the transition between modes are described in detail below with reference to fig. 5.

Blocks 202 and 204 of method 200B are similar to those of method 200A and are not described in detail herein. At 206, it is determined whether an uplink signal from terminal device 106 was received during the time threshold. The uplink signal may be a feedback signal of the terminal device 106 for the first discovery signal or the second discovery signal. One of the purposes of making this determination is to determine whether there is a terminal device 106 within the coverage of the transmission point 104-1 that needs to access the network.

If it is determined that there is a terminal device 106 that requires access, the method 200B returns to block 204 for transmission point 104-1 to continue transmitting the second discovery signal. On the other hand, if it is determined that there is no terminal device 106 that needs to access the network, the second discovery signal is set to an inactive mode at 208. In this way, interference to other transmission points 104 may be advantageously reduced and power consumption of the transmission point 104-1 itself may be reduced. In some embodiments, the mode switching is based on measurements of uplink triggered reference signals for the terminal device 106.

At 210, an indication that the second discovery signal is set to an inactive mode is transmitted in the first discovery signal. As a non-limiting example, a special field may be set in the first discovery signal to indicate that the second discovery signal is in an inactive mode. In some embodiments, transmission point 104-1 may enter an active mode in response to receiving feedback from terminal device 106 or receiving an instruction from a device in RAN 100 at a certain time. Accordingly, the second discovery signal will be retransmitted.

Fig. 3 illustrates a block diagram of a discovery signal according to an embodiment of the present disclosure. The first discovery signal shown in fig. 3 may include a synchronization signal SS 302 in the first layer discovery signal and necessary system information ESI 304 in the first layer discovery signal. It should be understood that although FIG. 3 shows the first discovery signal including both the SS 302 in the first tier discovery signal and the ESI 304 in the first tier discovery signal, the first discovery signal may include one of the two. The SS 302 in the first layer discovery signal carries the cell identity of the cell 108 and may provide initial downlink synchronization for terminal devices 106 under the coverage of the cell 108, while the ESI 304 in the first layer discovery signal carries limited necessary system information as well as information about the transmission point 104-1 in the cell 108. The limited necessary system information carried by ESI 304 in the first tier discovery signal may include the bandwidth provided by the system, etc. Information about the transmission point 104-1 such as the resource configuration of the SS 306 in the second layer discovery signal and the necessary system information ESI 308 in the second layer discovery signal. The information related to transmission point 104-1 may also include a BRS 406 in the second layer discovery signal as shown in fig. 4. In embodiments herein, "first layer" and "first" and "second layer" and "second" may be used interchangeably to distinguish between two discovery signals.

The SS 302 in the first tier discovery signal and the ESI 304 in the first tier discovery signal occupy preconfigured time-frequency resources to be transmitted in a first cycle 310. In the case of a cell 108 having multiple transmission points 104, the SS 302 in the first layer discovery signal and the ESI 304 in the first layer discovery signal are transmitted simultaneously by all or some of the transmission points 104 in the cell 108 on the same time-frequency resources in a manner similar to a single frequency network, and use increased transmission power and/or wider beam bandwidth to achieve suitable signal coverage to provide quality of signals received by high terminal devices 106. This is advantageous when the system is operating in the millimeter wave band, since the path loss of the signal increases rapidly with transmission distance.

The second layer discovery signals are transmitted in the form of SS 306 in the second layer discovery signals and ESI 308 in the second layer discovery signals specific to transmission point 104-1 to be used primarily for beam scanning and beam identification and feedback between the transmission point 104-1 and the terminal device 106. It should be understood that although fig. 3 shows that the second discovery signal includes both the SS 306 in the second layer discovery signal and the ESI 308 in the second layer discovery signal, the second discovery signal may include one of the two. In the case of the SS 306 in the second layer discovery signal and the ESI 308 in the second layer discovery signal specific to the transmission point 104-1, the SS 306 in the second layer discovery signal optionally carries the identification of the transmission point 104-1 and may support beam scanning and beam alignment as well as beam recognition and feedback for the transmission point 104-1 operating in the mmwave band. The ESI 308 in the second layer discovery signal may optionally be present to provide other necessary system information specific to the cell 108 and system information specific to the transmission point 104-1.

As previously described, in addition to achieving synchronization and acquiring necessary system information, the second discovery signal may be used to support beam scanning/alignment and beam tracking between the transmission point 104-1 and the terminal devices 106 within the coverage of the transmission point 104-1. Depending on the radio architecture of the transmission point 104-1 used, the transmission point 104-1 may require different resource configurations to transmit the SS 306 in the second layer discovery signal and the ESI 308 in the second layer discovery signal. Radio frequency architectures such as all-digital beamforming architectures and hybrid beamforming architectures. There are the same number of radio frequency chains and antennas in an all-digital beamforming architecture. The number of antennas in the hybrid beamforming architecture is much larger than the number of radio frequency chains. The time/frequency/code resource for scanning one transmission beam is represented as one transmission beam scanning (TxBS) resource unit, which is needed if N transmission beams are needed to cover the entire transmission point area. Implementation of the system design becomes complex if the configuration of the N TxBS resource elements depends on the radio frequency architecture used by transmission point 104-1.

The indication of the SS 306 in the second tier discovery signal and the ESI 308 in the second tier discovery signal by the ESI 304 in the first tier discovery signal presented in this disclosure may effectively address the problems caused by different radio frequency architectures. As shown in fig. 3, the different TxBS resource units are multiplexed in a frequency division multiplexing manner. This is particularly suitable for all-digital radio frequency architectures, since different beam-specific beamforming can be flexibly implemented in the baseband. For hybrid architectures, analog beamforming will only be implemented in wideband. In certain embodiments, different TxBS resource elements can also be multiplexed in other manners, such as Time Division Multiplexing (TDM) or hybrid frequency division multiplexing/time division multiplexing (FDM/TDM), depending on the particular radio frequency architecture used.

In certain embodiments, the SS 302 in the first layer discovery signal may reuse existing primary and secondary synchronization signals (PSS/SSs) in the LTE system. This is because the purpose of the first synchronization signal is to provide downlink synchronization, i.e. not to relate to beam scanning/beam alignment. The signal structure of the second synchronization signal is designed in such a way that the second synchronization signal can be used to provide beam scanning/alignment and optionally synchronization. The second synchronization signal may also be enhanced over the existing LTE PSS/SSS structure to provide efficient support for beam scanning/alignment.

In some embodiments, the SS 302 in the first layer discovery signal may carry a cell identification. The SS 306 in the second layer discovery signal optionally carries a transmission point identification to distinguish transmission points 104 in the cell. For general data/control channel/signal transmission, the scrambling or sequence generation can be designed as a function of cell identity and transmission point identity. The transmission point identification may be used to reduce interference between transmission points 104 in a cell 108, and the cell identification may be used to reduce interference between cells. In some embodiments, similar to coordinated multipoint transmission for carrier aggregation, scrambling or sequence generation needs to be specifically designed.

In some embodiments, to achieve reliable coverage of a cell, a first discovery signal is transmitted by all or some of the transmission points 104 in the cell 108 in a single frequency network manner in synchronization on the same time-frequency resource, using an increased transmission power; while the second discovery signal is transmitted by transmission point 104-1 using beam sweeping to overcome the large path loss and blockage at high frequencies. In some embodiments, transmission point 104-1 may implement adaptive power adjustment.

Fig. 4 illustrates a block diagram of a discovery signal according to another embodiment of the present disclosure. Unlike the second discovery signal in fig. 3, the second discovery signal in fig. 4 includes a second layer beam reference signal BRS 406 for one or more beams. It should be understood that the difference in the structure of the discovery signal in the embodiment shown in fig. 3 and the discovery signal in the embodiment shown in fig. 4 is that the second discovery signal is different, and these two discovery signals are non-limiting examples of the discovery signal of the present disclosure. The sequence and/or occupied time-frequency resources of the BRS 406 indicate the identification information of the first transmission point and the beam used by the first transmission point for transmission. The purpose of the second layer BRS 406 is to provide beam scanning/beam alignment. The second layer BRSs 406 may be multiplexed using a CDM/FDM/TDM manner, with one rectangle 408 in fig. 4 representing time-frequency resources, and multiple orthogonal or quasi-orthogonal BRS sequences may be multiplexed using code division multiplexing, CDM.

In some embodiments, the synchronization signal SS 402 in the first layer discovery signal may carry the identity of the cell 108, while for the BRS 406 in the second layer discovery signal, different orthogonal BRS sequences may be used in the transmission point 104-1 to identify different transmission beams of the transmission point 104-1. The BRS sequences used by the transmission points 104 in the cell 108 may be jointly designed such that the BRS sequences between the transmission points 104 may be orthogonal or quasi-orthogonal in order to suppress potential inter-beam interference.

In some embodiments, the terminal device 106 may analyze the BRS 406 in the received second layer discovery signal and determine the transmission beam used for data transmission. In some embodiments, the terminal device 106 may obtain an index of the selected transmission beam. The index of the transmission beam selected by the terminal device 106 is fed back to the network device 102, and the transmission point 104 to which the selected beam belongs can be derived by the network device 102 from the index of the transmission waveform of the transmission point 104 in the cell. In certain embodiments, an index of the transmission waveform is stored in a memory of the network device 102. It should be understood that the device receiving the feedback of the terminal device 106 may also be other network nodes in the communication system than the network device 102. Fig. 5 illustrates a block diagram of a discovery signal according to yet another embodiment of the present disclosure. It can be seen that only the first discovery signal is present in fig. 5, i.e., transmission point 104-1 does not transmit the second discovery signal. Not transmitting the second discovery signal may reduce interference and improve resource efficiency and power efficiency. All or a portion of the transmission points 104 within the cell 108 transmit the first discovery signal to facilitate initial access by the terminal device 106. This is particularly applicable in case there is no terminal device 106 in the coverage area of transmission point 104-1, since in this case no second discovery signal specific to transmission point 104-1 is required. This not only reduces interference between transmission points, but also reduces power consumption of transmission point 104-1.

In some embodiments, the first discovery signal indicates that the second discovery signal is in an active mode or an inactive mode. In some embodiments, it may not be actually necessary to have the transmission point 104-1 transmit the second discovery signal, for example, in the absence of a TE within the coverage area of the transmission point 104-1. Ceasing to transmit the second signal may reduce interference between transmission points 104 while reducing power consumption of transmission point 104-1.

In some embodiments, the second discovery signal enters an inactive mode in response to not receiving an uplink signal from terminal device 136 during the time threshold. In some embodiments, the system operates at low frequencies, such as below 6GHz, without beam scanning, and the second layer discovery may be set to inactive mode. In some embodiments, in the case of a terminal device 106 within the coverage area of the transmission point 104-1, the second discovery signal may need to be transmitted to support beam scanning/alignment and beam tracking between the transmission point 104-1 and the terminal device 106, whether the terminal device 106 is in an idle or connected state.

Fig. 6 shows a block diagram of an apparatus 600 for initial access of a terminal device 106 in a radio access network RAN 100 according to an embodiment of the present disclosure. In some embodiments, the apparatus 600 may be implemented as the first transmission point 104-1. There are multiple transmission points 104 in a cell 108 in the RAN 100. The apparatus 600 includes a first discovery signal transmission unit 602 and a second discovery signal transmission unit 602. The first discovery signal transmission unit 602 is configured to transmit a first discovery signal associated with a cell 108 in the RAN 100 at a first transmission point 104-1 of the plurality of transmission points 104 with a first periodicity 310 in synchronization with a second transmission point 104-2 of the plurality of transmission points 104. The second discovery signal transmission unit 602 is configured to transmit, at the first transmission point 104-1, a second discovery signal associated with the first transmission point 104-1 at the second periodicity 312, the first discovery signal indicating resource configuration information of the second discovery signal.

For clarity, certain optional modules of the apparatus 600 are not shown in fig. 6. However, it should be understood that the various features described above with reference to fig. 2 apply equally to apparatus 600. Furthermore, each module of the apparatus 600 may be a hardware module or a software module. For example, in some embodiments, apparatus 600 may be implemented in part or in whole using software and/or firmware, e.g., as a computer program product embodied on a computer-readable medium. Alternatively or additionally, the apparatus 600 may be implemented partly or entirely on a hardware basis, e.g. as an Integrated Circuit (IC), an Application Specific Integrated Circuit (ASIC), a system on a chip (SOC), a Field Programmable Gate Array (FPGA), etc. The scope of the present disclosure is not limited in this respect.

Fig. 7 illustrates a block diagram of a device 700 suitable for implementing embodiments of the present disclosure. The device 700 may be used to implement the transmission point 104. As shown, the device 700 includes a controller 710. The controller 710 controls the operation and functions of the device 700. For example, in certain embodiments, controller 710 may perform various operations by way of instructions 730 stored in a memory 720 coupled thereto. The memory 720 may be of any suitable type suitable to the local technical environment and may be implemented using any suitable data storage technology, including but not limited to semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems. Although only one memory unit is shown in FIG. 7, there may be multiple physically distinct memory units within device 700.

The controller 710 may be of any suitable type suitable to the local technical environment and may include, but is not limited to, one or more of general purpose computers, special purpose computers, microcontrollers, digital signal controllers (DSPs), and controller-based multi-core controller architectures. The device 700 may also include a plurality of controllers 710. The controller 710 is coupled to a transceiver 740, and the transceiver 740 may enable the reception and transmission of information by way of one or more antennas 750 and/or other components.

When the device 700 is acting as a transmission point, the controller 710 and the transceiver 740 may operate in cooperation to implement the

methods

200A and 200B described above with reference to fig. 2A and 2B. All of the features described above with reference to fig. 2 apply to the apparatus 700 and are not described in detail here.

In describing embodiments of the present disclosure, the terms "include" and its derivatives should be interpreted as being open-ended, i.e., "including but not limited to. The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment".

It should be noted that the embodiments of the present disclosure can be realized by hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or specially designed hardware. Those skilled in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such code being provided, for example, in programmable memory or on a data carrier such as an optical or electronic signal carrier.

Further, while the operations of the methods of the present disclosure are depicted in the drawings in a particular order, this does not require or imply that these operations must be performed in this particular order, or that all of the illustrated operations must be performed, to achieve desirable results. Rather, the steps depicted in the flowcharts may change the order of execution. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step execution, and/or one step broken down into multiple step executions. It should also be noted that the features and functions of two or more devices according to the present disclosure may be embodied in one device. Conversely, the features and functions of one apparatus described above may be further divided into embodiments by a plurality of apparatuses.

While the present disclosure has been described with reference to several particular embodiments, it is to be understood that the disclosure is not limited to the particular embodiments disclosed. The disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method in a Radio Access Network (RAN) for initial access by a terminal device, a cell in the RAN having a plurality of transmission points therein, the method comprising:

transmitting, at a first transmission point of the plurality of transmission points, a first discovery signal associated with the cell in the RAN at a first periodicity in synchronization with a second transmission point of the plurality of transmission points; and

transmitting, at the first transmission point, a second discovery signal associated with the first transmission point at a second periodicity, the first discovery signal indicating resource configuration information of the second discovery signal.

2. The method of claim 1, further comprising:

in response to not receiving an uplink signal of the terminal device during a time threshold, setting the second discovery signal to an inactive mode; and

transmitting an indication in the first discovery signal that the second discovery signal is set to the inactive mode.

3. The method of claim 1, wherein the first discovery signal carries the cell-specific information comprising at least a cell identification, a partial system message, and the resource configuration information of the second discovery signal, and the second discovery signal carries the first transmission point-specific information comprising at least identification information of the first transmission point and beam information used by the first transmission point.

4. The method of claim 1, wherein the first discovery signal comprises at least one of:

a first synchronization signal for synchronization between said terminal device and said cell, an

First required system information (ESI) for indicating the resource configuration information of the second discovery signal and at least partial system information of the cell.

5. The method of claim 1, wherein the second discovery signal comprises at least one of the following to indicate a beam transmitted by the first transmission point:

a second synchronization signal for synchronization between said terminal device and said first transmission point, an

Second necessary system information (ESI) for indicating at least part of system information of the cell and the first transmission point related information.

6. The method according to claim 1, wherein the second discovery signal comprises Beam Reference Signals (BRSs) of one or more beams, a sequence of the BRSs and/or occupied time-frequency resources indicating identification information of the first transmission point and a beam used for transmission.

7. The method of claim 1, wherein the first transmission point and the second transmission point in the cell synchronously transmit the same first discovery signal on the same time-frequency resource in a single frequency network manner.

8. The method of claim 1, wherein the first periodicity is an integer multiple of the second periodicity.

9. The method of claim 1, wherein a power and/or a beam width used for transmitting the first discovery signal is greater than a power and/or a beam width used for transmitting the second discovery signal.

10. A transmission point in a Radio Access Network (RAN) having the transmission point and at least one other transmission point in a cell in the RAN, the transmission point comprising:

a controller;

a memory storing instructions that, when executed by the controller, cause the transmission point to perform acts comprising:

transmitting, at the transmission point, a first discovery signal associated with the cell in the RAN at a first periodicity in synchronization with the at least one other transmission point; and

transmitting, at the transmission point, a second discovery signal associated with the transmission point at a second periodicity, the first discovery signal indicating resource configuration information of the second discovery signal.

11. The transmission point of claim 10, the actions further comprising:

in response to not receiving an uplink signal of a terminal device during a time threshold, setting the second discovery signal to an inactive mode; and

12. The transmission point of claim 10, wherein the first discovery signal carries the cell-specific information including at least a cell identification, a partial system message, and the resource configuration information of the second discovery signal, and the second discovery signal carries first transmission point-specific information including at least identification information of the first transmission point and beam information used by the first transmission point.

13. The transmission point of claim 10, wherein the first discovery signal comprises at least one of:

a first synchronization signal for synchronization between the terminal device and said cell, an

14. The transmission point of claim 10, wherein the second discovery signal includes at least one of:

a second synchronization signal for synchronization between the terminal device and said transmission point, an

Second necessary system information (ESI) for indicating at least part of system information of the cell and the transmission point related information.

15. The transmission point according to claim 10, wherein the second discovery signal comprises Beam Reference Signals (BRSs) of one or more beams, and the sequence of BRSs and/or occupied time-frequency resources indicate identification information of the first transmission point and the beam used for transmission.

16. The transmission point of claim 10, wherein the transmission point and the at least one other transmission point in the cell synchronously transmit the same first discovery signal on the same time-frequency resources in a single frequency network manner.

17. The transmission point of claim 10, wherein the first periodicity is an integer multiple of the second periodicity.

18. The transmission point of claim 10, wherein a power and/or a beam width for transmitting the first signal is greater than a power and/or a beam width for transmitting the second discovery signal.

19. A computer storage medium storing instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1-9.