CN110225570B - Method, terminal and cell for system information distribution in wireless access telecommunication system - Google Patents

Method, terminal and cell for system information distribution in wireless access telecommunication system Download PDF

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Publication number
CN110225570B
CN110225570B CN201910423445.3A CN201910423445A CN110225570B CN 110225570 B CN110225570 B CN 110225570B CN 201910423445 A CN201910423445 A CN 201910423445A CN 110225570 B CN110225570 B CN 110225570B
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cell
terminal
system information
area cell
small
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CN110225570A (en
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张海滨
柳普乔.约尔乔斯基
乔布.康奈利.奥斯迪文
雅各布.康奈利.范德瓦尔
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Tno Netherlands Applied Science Research Organization
Koninklijke KPN NV
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Koninklijke KPN NV
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/32—Hierarchical cell structures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
    • H04W48/10—Access restriction or access information delivery, e.g. discovery data delivery using broadcasted information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
    • H04W48/12—Access restriction or access information delivery, e.g. discovery data delivery using downlink control channel

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention relates to a wireless access telecommunication network system comprising at least a small area cell with which a terminal in active mode is configured to establish a data connection and a large area cell in idle mode in which the terminal is configured to camp. A method for a terminal to obtain at least large area cell system information and small area cell system information includes the terminal receiving at least a first portion of large area cell system information and at least a first portion of small area cell system information from a large area cell over a large area cell radio interface when the terminal is in an idle mode and the large area cell radio interface of the terminal is enabled.

Description

Method, terminal and cell for system information distribution in wireless access telecommunication system
Technical Field
The present invention relates generally to the field of wireless telecommunications, and in particular to the field of distributing system information from a cell to a terminal.
Background
Cellular radio access telecommunications networks (systems) typically comprise a plurality of base stations, for example: known base transceiver stations in GSM, NodeB in wcdma (umts) and evolved NodeB or eNB in LTE. A base station comprises at least transmitting and receiving equipment, commonly known as UE (user equipment), in the standard, to support wireless communication with terminals, which may be mobile. The coverage of the transmitter/receiver in the base station is limited. The area that a transmitter/receiver can serve in a base station is called the "coverage area" or "cell". The term "cell" refers to the base station itself and the coverage area associated therewith. Typically a cell relates to a particular sector (e.g. 120 degrees) radiating outward from a base station location, and multiple sectors (cells) may cover the entire area around the base station location, or may cover a particular area of interest (e.g. a narrow sector to cover a highway portion).
The cells (base stations) in a cellular network are typically connected to the rest of the network by one or more backhaul links, e.g. by optical fibre, copper wire or wireless. The cell also includes processing capabilities, such as processing for wireless transmission, reception, and specific protocols between the base station and the terminal, and between the base station and the network, including other base stations (cells).
In a cellular network, different cells have different sizes, for example, represented as macro cells (macrocells), micro cells (microcells), pico cells (picocells), or femto cells (femtocells) in order of decreasing cell size. Cells may appear to partially overlap with neighboring cells or smaller area cells (e.g., pico cells) may be completely covered by larger area cells (e.g., macro cells), and multiple cells may form a cellular network, providing nearly continuous coverage over a very large area.
In cellular wireless networks, it is common to distinguish whether a terminal is in "idle mode" or "active mode". In the active mode, the terminal is able to exchange data (e.g. send/receive e-mail or establish a telephone call) through the cell in which it is located. This requires network resources (such as frequency and/or coding and/or time slots) and also requires the terminal and the network to provide a certain target power consumption. In idle mode, the terminals cannot exchange data, and therefore do not require the above resources, consuming less power. Idle mode terminals need only periodically listen to the signals broadcast by the cells and select the "best cell", e.g., the cell with the strongest signal that the terminal can receive. The terminal in idle mode also listens to the paging channel for the selected cell to transmit paging messages to the terminal. Such (idle mode) terminals are said to "camp on" the selected cell. When a different cell is identified as the best cell, the terminal may reselect the different cell as the "best cell" and camp on the newly selected cell, e.g., due to mobility of the terminal. It should be noted that a terminal in idle mode typically does not inform the cell and/or the network which cell it resides in, nor when to reselect a different cell as the best cell. When the terminal reselects a cell, which is located in a different location area (LA, i.e. local area or RA, i.e. routing area), which is determined by the terminal according to the cell system information, the terminal then performs a LA or RA update procedure (including the exchange of signaling or network control information between the terminal and the cell) via the newly selected cell to initiate a connection with the network, and then continues its listening behavior, as described above. In this way the network can learn the LA/RA where the idle terminal is located. The LA/RA typically includes a plurality of cells configured by the network operator. Therefore, the network does not know in which cell a terminal in idle mode resides, it can only know in which LA/RA an idle terminal is (is expected to be) in.
In wireless telecommunications cellular networks, it is common for each cell, i.e. base transceiver station, NodeB and eNB, to be in operation, to broadcast so-called "system information" to terminals within the cell's coverage area. This can be represented by the schematic diagram shown in fig. 1, where a cell 1 broadcasts within its coverage area (the lightly shaded sectors shown in fig. 1) system information 9, which can be received by terminals 2 within the cell, and fig. 1 also depicts the connection of the cell 1 to the network 3.
The system information transmitted by a cell relates to a wide range of information related to cell and/or network operation, and some examples of system information and use of this information by terminals are provided below. Those skilled in the art will recognize that system information may include one or more of such examples, as well as other system information that the terminal can configure itself based on the received information.
In one example, the system information can include a network indication, such as a Public Land Mobile Network (PLMN) to which the cell belongs, that enables the terminal to receive this information to determine whether the terminal can use the cell at all. In another example, the system information may include an indication of the cell status, e.g., whether the cell is in an operational state and/or whether there are any restrictions such as access class, application. This information enables the terminal to determine whether the terminal is available at the time. Furthermore, the system information also includes an indication of a Cell identity (Cell ID), enabling the terminal to determine that the Cell identity is in the network. In other examples, the system information may include indications of cell configuration, such as frequencies, frequency bands, codes or time slots in which the cell operates and channel configuration information provided by the cell, indications of parameters such as frequencies, channels and codes that enable the terminal to configure the correct settings to receive various channels and/or RACH (random access channel) of the cell, and enable the terminal to initiate a connection with the cell. Still further, the system information may include neighbor cell information, such as a neighbor cell list including the identity and/or transmission frequency and/or code and/or time slot of the neighbor cell. If the network supports multiple Radio Access Technologies (RATs), such as GSM (GERAN-GPRS/EDGE radio access network), UMTS (UTRAN-universal terrestrial radio access network, employing WCDMA-wideband code division multiple access), or LTE (E-UTRAN-evolved UTRAN, employing OFDM, i.e. orthogonal frequency division multiplexing), neighbor cell information may be provided separately by each RAT, which facilitates the (fast) discovery of neighbor cells by the terminal, which can be entered for example for the purpose of reselection or handover to a potential cell. In yet another example, the system information may include an indication of criteria that allow the network to inform the terminal that it should apply in the network and/or cell, such as reselecting a cell and/or performing reporting measurements neighbor cell thresholds and/or at other frequencies and/or RATs.
It is common for a cell to broadcast system information, e.g. in a broadcast channel, which can be received by all terminals in the cell coverage area. Typically, the cells transmit the system information cyclically in a time-sequential order, in a substantially continuous manner, for example cyclically repeating the system information with a rotating structure as shown in fig. 2. As shown in FIG. 2, loop 4 includes system information having different categories, represented as blocks M, S1, S2, S3, and S4, organized together. Block M is used to describe the example Master Information Block (MIB), containing the system information necessary for most or all terminals in the network, while blocks S1-S4 are used to describe additional System Information Blocks (SIBs), carrying additional information needed by only some terminals. Loop 4 may be the system information that is continuously repeatedly transmitted as shown in sequence 5, and sometimes some of the system information blocks may also be replaced by other blocks, such as the last blocks S3 and S4 in sequence 6 shown in sequence 6 being replaced by new system information blocks S5 and S6. Nevertheless, in the sequences 5 and 6 shown in fig. 2, the system information is continuously transmitted.
A tradeoff should be made between using a large portion of the cell resources (e.g., high code rate and/or wide frequency band) and using a small portion of the cell resources for broadcasting system information. Short cycle times can be achieved with a large fraction of the resources, enabling the terminal to receive all system information with only small delays, but requiring considerable cell resources. In contrast, utilizing a small portion of the resources may cause a longer cycle time, the terminal having to accept higher delays in receiving all or certain system information.
In the state of the art, flexible and efficient distribution of system information has been fully appreciated. However, in practice, broadcasting such information requires both partial cell resources and transmission power consumption and energy consumption of partial cells. Although this is only a small fraction (e.g. less than 10%) of the peak power consumption of the cell, it should be noted that this consumption is substantially constant, and especially during periods of only small traffic load, the distribution of system information may also involve a significant proportional expense. There thus appears to be room for improvement in terms of distributing system information in a resource efficient manner under conventional network architectures.
Recently, a new and more energy efficient network architecture has been developed, in which on the one hand relatively small cells are used, and on the other hand high rate data connections are more efficient than using a small number of large area cells (e.g. macro cells) and a large number of (at least partially overlapping) small area cells (e.g. micro cells, pico cells). On the other hand, in the new architecture, the power consumption of the cell is also as predictable as possible according to the services actually provided (e.g., the number of terminals in an active state, the code rate provided to the terminals, the distance traveled to connect to the terminals, etc.). To fulfill this desire, one method involves putting terminals that are not really active into a power saving mode, e.g. switching off the cells almost entirely. Another complementary approach involves the major reduction or limitation of the transmission of common broadcast signals in conventional networks, the transmission of which can incur substantial power consumption expenditures, especially for cells operating less than fully loaded.
As shown in fig. 3, the new architecture assumes a division into two types of cells. The first type of cell, referred to herein as a "small-area cell," such as cell 7 in fig. 3, is primarily used for optimization for wireless data exchange with the active terminal 2, and the energy-efficient improvements described above are primarily focused on small-area cells. The second type of cell, referred to herein as a "large area cell," such as cell 8 in fig. 3, is primarily used to optimize other functions of the cellular network, including that which is also present in conventional networks. It is also anticipated that this will reduce the system overhead allocated to large area cells.
Large area cells typically cover a larger area, e.g. compared to conventional macro cells. Large area cells can provide nearly continuous coverage in areas where coverage is desired, similar to conventional networks. The large area cell can broadcast system information like a conventional cell, and an idle terminal can reside in the large area cell and can also initiate signaling connection with the large area cell, such as performing LA/RA update or disconnecting from the network.
Small area cells typically cover a smaller area, e.g. compared to conventional microcells, picocells, femtocells. Small area cells can provide a specific code rate in a nearly continuous area that one wishes to cover. A small area cell transmits signals only when necessary, typically in an "off" or otherwise power saving or standby mode. Idle terminals also do not camp on a small area cell. Although this network is referred to as a "beyond cellular Green Generation" (BCG2) network, the term may change in the future. Therefore, in the present invention, a network having such an architecture will be referred to as an "energy efficient cellular wireless network".
Since a terminal must handle both types of cells in an energy efficient cellular radio network, one or more large area cells and one or more related small area cells, the terminal also needs related system information for one or more related large area cells and one or more related small area cells, resulting in two problems.
One problem arises from the fact that when an idle terminal is active, such as an idle terminal establishing a data session, referred to as a "session set-up" operation, a suitable small-area cell needs to be selected as supporting the session. In the process of establishing a session, the terminal also needs to obtain relevant system information, such as cell identity, frame timing, cell bandwidth, etc., for one or more candidate small-area cells. Also, when a suitable small-area cell for the session is selected, the terminal requires system information attached to the small-area cell. If the selected small area cell is currently off or in said power saving mode in BCG2, the small area cell needs to be activated. It takes some time to select and activate a suitable small area cell. As a result, it takes a period of time to provide necessary system information to the terminal before the small-area cell is sufficiently activated. In addition, since the concept of an energy efficient cellular radio network gives an efficient and dynamically configured small-area cell, previously obtained small-area cell system information using a specific small-area cell (e.g. obtaining stored small-area cell system information when a session was previously established) will bear a high risk that the previously obtained small-area cell system information is no longer valid, and therefore it is necessary to provide the terminal with the relevant up-to-date small-area cell system information in order to quickly establish a data session with the appropriate small-area cell.
Another problem arises from the fact that when an active terminal assumes idle mode after completing all data sessions, the terminal needs to camp back on a large area cell. For this purpose, the terminal performs a cell search and/or cell reselection procedure during which the terminal needs to obtain system information, such as cell identity, frame timing, cell bandwidth, paging channel, etc., related to one or more candidate large area cells. In energy efficient cellular wireless networks, while large area cell configurations may be less dynamic than small area cell configurations, employing previously obtained large area cell system information (such as large area cell new system information obtained prior to establishing a data session) still risks that previously obtained stored large area cell system information is no longer valid. This may be the case because the large area cell system information has been modified at this time or the large area cell system information is no longer relevant, for example because the terminal moved to a different large area cell coverage area, which does not have any previously obtained relevant information stored. To obtain the relevant up-to-date large area cell system information, the terminal can again perform a cell search procedure similar to that in operation. Thus, it takes a while for the terminal before it finds a suitable large area cell to camp on and can listen again to the paging channel of the large area cell. As a result, when the terminal enters idle mode from active mode, the latest large area cell system information provided to the terminal is needed to enable the terminal to quickly re-camp on a suitable large area cell (which may be the same or a different large area cell as the cell in which the terminal was camped before the data session was established).
In light of the foregoing, a method and system for distributing system information in a legacy network in a more energy efficient manner is needed. Furthermore, there is a need in the art for a method and system for allocating large area cell system information and small area cell system information in an energy efficient cellular wireless network, such as a BCG2 network, in a manner that addresses the above problems, and that is preferably energy efficient radio resources, energy efficient and capable of meeting the efficient requirements of hardware and terminal computing resources.
Disclosure of Invention
According to a first aspect of the present invention, in a wireless access telecommunication network system, comprising at least a small area cell and a large area cell, a terminal in an active mode is configured to establish a data connection with the small area cell, and the terminal is configured to camp in the large area cell in an idle mode, a method for a terminal to obtain at least large area cell system information and small area cell system information. The method comprises the following steps: the terminal receives a first portion of large area cell system information for at least the terminal and a first portion of small area cell system information for at least the terminal from the large area cell over the large area cell radio interface when the terminal is in idle mode and the large area cell radio interface for the terminal is enabled.
The implementation of this scheme is based on the idea that a large area cell can be used to transmit large area cell system information and at least cell area cell system information related to a small area cell that may be associated with a terminal within the coverage area of the large area cell. In another embodiment, the large area cell may be configured to transmit all system information to the terminals using a broadcast/common channel, while in an alternative embodiment, the large area cell may be configured to transmit at least part of the system information to individual terminals using one or more dedicated signaling channels.
In an embodiment, the method further comprises the terminal configuring one or more settings based at least in part on the received small area cell system information and/or the received large area cell system information, and optionally the terminal may store at least part of the received small area cell system information and/or the large area cell system information for future use. In another embodiment, the idle terminal may only apply the received and possibly stored large area cell system information to configure its settings as long as it is in idle mode, whereas the received small area cell system information may only be stored for possible later use. The terminal may also apply the received and possibly stored small-area cell system information only when the terminal is to enter an active mode, to further configure the settings of the particular small-area cell to which the terminal is to be connected and/or to which it has been connected.
The phrases "information that a cell sends to a terminal", "information for a terminal", and variations thereof, as used herein, describe system information that is used to send to a terminal, such as for the benefit of the terminal. For example, some system information is mainly used to transmit to a terminal in an idle mode, and other system information is used to transmit to a terminal regardless of its mode. In this regard, it does not matter whether the system information transmitted by a cell is actually received and/or used by terminals, e.g., when a cell transmits system information over a broadcast channel, it enables all terminals within the coverage area of the cell to receive the system information. In fact, however, not all but only some terminals are interested in the transmitted system information, while others are not. Moreover, not all but only some of the terminals that may be interested in the transmitted system information actually receive, while other terminals may not receive (e.g., due to transmission errors, due to the terminals performing other tasks, etc.), e.g., because the transmitted system information has been previously obtained, other terminals may only, or may intentionally, ignore those transmissions.
In the embodiments of the present invention, the words "large area cell" and "small area cell" are used to distinguish two different types of cells.
The first type of cell, a Large Area cell (LA-cell), refers to a cell that can cover a larger Area and has a lower code rate than the second type of cell. The large area cell is mainly used for carrying signaling information to/from the terminal, for example, the large area cell can at least page the terminal. A terminal in idle mode should be able to "camp on" at least one such large area cell. The large area cell is not primarily intended to carry wireless user data to/from the terminal, it does not exclude other signalling than paging or user data carried over the large area cell. In the area to be covered by the radio access network, at least one of the macro cells is in full operation, in other words, the macro cell is "normally open".
A second type of cell, a Small Area cell (SA-cell), refers to a cell that can cover a smaller Area and has a higher code rate than a Small cell. The small area cell is mainly used to carry user data which is received/sent to a terminal having established a data connection (e.g. the small area cell initially handles the connection established with the active terminal), but it does not exclude other information and/or signalling carried by the small area cell. In the area that the radio access network intends to cover, it can be assumed that the coverage can be provided by at least one small area cell. The small area cell is in full operation only when necessary to some extent, in other words, the small area cell is "normally closed".
Small area cells may exist in any of the mixed frequency bands and/or Radio Access Technologies (RATs) according to embodiments of the present invention, which does not preclude the existence of small area cells of different sizes (e.g., macro, micro, pico, and pico cells, with or without hierarchical organization), where larger small area cells may more efficiently serve mobile terminals.
In application, the expression "data connection between a terminal and a small-area cell" refers to a communication path for wireless exchange of user data between the terminal and the small-area cell. The communication path for this user data, including the part between the terminal and the small-area cell, is typically established according to a set of parameters, e.g. based on which type of user data needs to be exchanged (e.g. for sending/receiving e-mail, for voice or video telephony, etc.). The set of parameters, commonly referred to in the art as "QoS parameters" or "QoS classes," may include parameters such as maximum code rate, guaranteed (minimum) code rate, bit error rate, and deferral/delay.
In contrast, the signalling messages exchanged between the terminal and the large area cell, which do not contain user data, are exchanged between the terminal and the various entities in the telecommunication system, the signalling messages being exchanged without establishing a connection but through a "signalling connection" having a suitable code rate and being able to achieve high quality signalling information without losses. When using a signalling connection, it is largely independent of the "data connection" parameters to which it can be connected.
Further, it is to be understood that the words "user data" and "user terminal" do not necessarily imply the presence of a human user, and that embodiments of the present invention are applicable to collating mail without human intervention, as in a smartphone, and to machine-to-machine (M2M) communications and/or Machine Type Communications (MTC). The word "user data" is used only to distinguish actual data for exchange with signalling over a data connection.
As described herein, a terminal may be either in an "active mode" or in an "idle mode". According to the usage herein, the expression "terminal in idle mode" means that the terminal is not exchanging user data nor user data, but resides in a large area cell and listens for possible paging messages from the large area cell to the terminal. In other words, the expression "terminal in idle mode" is used to describe that the terminal does not support wireless exchange of user data between the terminal and a small-area cell. Conversely, the expression "terminal in active mode" means that the terminal is either exchanging user data or is at least able to exchange user data via one small area cell. In other words, the active terminal supports or is capable of supporting wireless exchange of user data between the terminal and the small-area cell. The concepts of idle mode and active mode may correspond to those in standard legacy networks, but need not be exactly consistent with standard definitions.
In an embodiment, the method further comprises: the terminal receives at least a second portion of the small-area cell system information when the terminal is in an active mode and a small-area cell radio interface of the terminal is enabled. Additionally or alternatively, when the terminal is in an active mode and a small-area cell radio interface of the terminal is enabled, the method further comprises: the terminal receives at least a second portion of the large area cell system information from the small area cell over the small area cell radio interface.
In an alternative embodiment, the method further comprises: when the terminal is in the active mode and the small-area cell radio interface is enabled, the terminal enables the large-area cell radio interface for one or more time periods and receives at least a second portion of the large-area cell system information from the large-area cell over the large-area cell radio interface. In an embodiment, a terminal in active mode with a large area cell radio interface enabled may also receive a second portion of small area cell system information from the large area cell over the large area cell radio interface. In another embodiment, at least one of the one or more time periods occurs when a terminal in an active mode receives a trigger to enable the large area cell radio interface. The trigger may be one or more triggers provided to the terminal by the large area cell or by a network control entity in the radio access network through the small area cell, the terminal performing a handover from one small area cell to another in the radio access network, a timer within the terminal timing out.
In an embodiment, the method further comprises: when the terminal is in idle mode and the macro cell radio interface of the terminal is enabled, the terminal receives at least part of the cell system information from the macro cell over the macro cell radio interface, the part of the cell system information being related to at least one of the one or more other cell in the radio access network.
In an embodiment, the method further comprises: when the terminal is in idle mode, the terminal receives from the large area cell, via the large area cell radio interface, an activation status of at least one small area cell for receiving said small area cell system information.
In an embodiment, the method further comprises: deactivating the small area cell radio interface when the large area cell radio interface is activated, and deactivating the large area cell radio interface when the small area cell radio interface is activated.
According to another aspect of the present invention, a large area cell for use in the methods described herein is disclosed. The large area cell is at least configured to: obtaining a first portion of the at least small-area cell system information from the small-area cell and/or from a network management entity of a wireless access telecommunications network; and transmitting the first portion of the at least small area cell system information and the first portion of the at least large area cell system information. In an embodiment, the large area cell is also configured to obtain and send system information of other small area cells and/or other large area cells, which information can also be obtained from other cells directly and/or from a network management entity of the radio access telecommunications network.
In an embodiment, the first part of the at least large area cell system information is transmitted in a predetermined pattern, preferably periodically. In the active mode, the terminal may switch back to the macro cell interface to obtain the macro cell system information. Sending the large area cell system information in a predetermined pattern allows the terminal to know when to switch back to the large area cell interface.
In accordance with other aspects of the invention, small area cells for use in the methods described herein are disclosed. The small area cell is configured to at least: providing a first portion of the at least small-area cell system information to a large-area cell for transmission to a terminal.
According to other aspects of the invention, a terminal, a data carrier having (possibly allocated to) computer program portions for performing the various functions described herein, and a telecommunications system are disclosed. The telecommunication system comprises two or more terminals as described above, a large area cell and a small area cell.
Hereinafter, embodiments of the present invention will be described in detail, however, it should be understood that these embodiments are not to be construed as limiting the scope of the present invention.
Drawings
In the figure:
FIG. 1 is a diagram illustrating system information distribution in a conventional network;
fig. 2 is a schematic diagram of continuously transmitted system information according to the prior art;
FIG. 3 is a schematic diagram of a small area cell and a large area cell in an energy efficient cellular radio access telecommunications network;
FIG. 4 is a schematic diagram of intermittent periodic transmission of system information according to an embodiment of the present invention;
FIG. 5 is a diagram of triggered sending system information, according to various embodiments of the invention;
FIG. 6 is a schematic diagram of an energy efficient telecommunications system according to an embodiment of the present invention;
fig. 7 is a schematic diagram of coverage areas of a large area cell and a plurality of small area cells in a telecommunications network according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a terminal alternating between a small-area cell radio interface and a large-area cell radio interface in a time division multiplexing mode according to an embodiment of the present invention;
fig. 9 is a diagram illustrating a small-area cell providing small-area cell system information to a terminal and a large-area cell providing large-area cell system information to the terminal according to an embodiment of the present invention;
FIG. 10 is a flowchart of method steps for obtaining one or more small area cell system information and one or more large area cell system information, according to one embodiment of the invention;
fig. 11 is a diagram illustrating a large area cell providing large area cell system information and small area cell system information to a terminal according to an embodiment of the present invention;
fig. 12 is a diagram illustrating an example of a large area cell providing large area cell system information and small area cell system information to a terminal according to an embodiment of the present invention;
fig. 13 is a diagram illustrating a small-area cell providing a terminal with small-area cell system information and large-area cell system information according to an embodiment of the present invention; and
fig. 14 is a diagram illustrating a small-area cell providing a terminal with small-area cell system information and large-area cell system information according to another embodiment of the present invention.
Detailed Description
Schemes #1-4 below provide various methods and systems for distributing system information. Scenario #1 describes the conventional network referred to as shown in fig. 1, while scenarios #2-4 describe the use of the system information distributed in an energy efficient network. However, those skilled in the art will appreciate the teachings regarding system information allocation performed by cells in conventional networks, as scenario #1 may be applied to allocate system information by large area cells as well as small area cells in energy efficient networks.
Scheme #1 System information Allocation provided according to various embodiments of the present invention
Scheme #1 focuses primarily on the possibility of improving cell allocation system information efficiency (including energy efficiency). As described above, the scheme #1 is referred to the conventional network as shown in fig. 1, but the embodiment of the scheme #1 can be applied to the allocation of system information of any cell, not only to the conventional cell such as a base transceiver station, a NodeB or an eNB, but also to a small-area cell and/or a large-area cell in an energy-efficient network.
Scheme #1 provides five different ways to improve the energy efficiency of allocating system information in a cell. The first approach is based on broadcasting the system information for only a short period of time, leaving the rest of the time without transmitting any system information, rather than substantially continuously as is typical in the prior art. The second way is based on broadcasting system information when triggered by a specific event. A third approach is based on transmitting system information with substantially sharp power instead of using normal full power broadcast to ensure reliable reach to the farthest end, taking into account path loss, the marginal aspects of the cell's coverage area. A fourth approach is based on transmitting only the reduced portion of the system information without the usual cyclic transmission of the system information portion. A fifth way is based on transmitting system information only to specific terminals through dedicated channels instead of using a common broadcast channel and transmitting system information to all possible terminals within the cell coverage area, which five different ways are described in detail below.
1. Discontinuous transmission of system information (only for a short period of time)
A first way to achieve a more energy efficient allocation of system information is for a cell, such as cell 1 shown in fig. 1, to only transmit system information intermittently, e.g. for only a short period of time. For example, a cell may be configured to transmit a system information signal in 100 milliseconds (ms), followed by 900ms without any system information, corresponding to 1/10 times. To this end, the cell may comprise at least a transmitter and a controller to prepare for transmitting signals, the cell may further comprise a memory to store computer program instructions and a processing unit to process data and execute the computer program, the controller and/or the transmitter may perform operations according to the computer program instructions.
The period during which the system information signal is transmitted may correspond to a full cycle or a specific system information portion of the cell system information, which is schematically represented in fig. 4 with signal 10, in which a full cycle of cell system information 10a including blocks M, S1, S2, S3, S4 is transmitted during time period t1, and no system information is transmitted during an adjacent time period t 2. The cell can repeatedly transmit the signal 10 such that the system information blocks M and S1-S4 corresponding to 10a are repeatedly transmitted during the time period t1, and the system information corresponding to 10b, such as the signal 11 in the figure, is not transmitted during the adjacent time period t 2. Alternatively, some parts of the system information may be replaced by others, such as in signal 12, and in some cases the system information blocks S5 and S6 may replace blocks S3 and S4.
The time elapsed for transmitting the system information signal may also be shortened, for example corresponding to only a small portion of the system information (or portion of the system information) cycle. Thus, a full cycle of system information or a partial transmission of system information can be allocated over multiple periods of time during which system information signals are transmitted and not transmitted, such as signal 13 in fig. 4, thus increasing the time for the terminal to acquire all of the system information compared to a case where system information is transmitted substantially continuously.
The time elapsed for transmitting the system information signal may also be longer than a full cycle of system information or a portion of the system information. This may be the case, for example, for multiple cycles of system information or portions of system information during a period. In another example, this may be the case where the elapsed time corresponds to a single cycle of cell system information or a portion of system information plus an allowed margin, such as repeatedly transmitting information that the cell deems more important or is expected to be more urgent than other information in the system information or portion of system information, and thus hopefully more reliably transmitted information. This way of transmitting the system information enables the terminal to have a chance to acquire again within the same system information transmission period or double check the retransmitted system information part as soon as the terminal fails to receive the system information part or the terminal detects or suspects that it erroneously received the system information part.
Varying the duty cycle (e.g., the ratio of "on" time to "on" + "off" time for transmitting the system information or system information portion signal) in this manner allows the transmit power of the presence signal to be reduced to approximately the same fraction as compared to conventional methods in which the system information is transmitted substantially 100% of the time. In one embodiment, the maximum duty cycle for an inter-cell intermittent transmission of a system information or system information portion signal is, for example, 1/2 or 1/8, which can result in a 2-fold or 8-fold power savings, respectively, compared to continuously transmitting the same signal. Different duty cycles may be applied for transmission of different portions of system information, as determined by the urgency of the terminal's need for information (expected or desired).
The following example may describe the situation where, in the current system, when the terminal is operating, the terminal initiates a cell search procedure to find a suitable cell to camp on. As part of the procedure, the terminal needs to identify one or more candidate cells, for a particular candidate cell it may need to determine the network (public land mobile network) associated with the cell, the cell identity indication and/or the operational status of the cell (e.g. whether it is currently barring access by the terminal and/or may be overloaded). In typical applications of existing systems, it may be very good to broadcast system information substantially continuously or very frequently to match the terminal requirements. However, such broadcasting is very inefficient, such as no terminals operating in a particular cell and/or no terminals performing cell search procedures during a particular time period. According to an embodiment of the present invention, by transmitting system information required by a terminal to perform a cell search procedure only a small fraction of the time, e.g., once per second, to improve energy efficiency, a terminal that is to receive a particular system information portion has to wait for a period of time before actually receiving the information. In this example, the worst case latency would be one second, and on average, the latency would be half a second. Since latency is a concern, the time interval between successive transmissions of system information portions preferably has an upper bound such that the upper bound of the transmission does not exceed the upper bound of latency or delay that the terminal is expected to tolerate. The upper transmission bound may be chosen differently for different system information parts, for example when the terminal is able to tolerate a longer delay for a particular system information part than another system information part. For example, the upper transmission bound for system information containing cell handover parameters may be selected to be much higher than the upper transmission bound for system information containing cell RACH (random access channel) parameters, e.g., RACH parameters are required before a terminal initiates a connection to a selected cell via RACH, whereas cell-related handover parameters may not be immediately required by a terminal handing over to a new cell.
In one embodiment, the time interval between successive transmissions of system information portions or the upper bound of the interval may be modified at any time, for example at peak times, such as in the morning when people tend to turn on the mobile phone, a lower value, such as 0.25 seconds, may be selected as the upper bound for the transmissions of system information portions for the terminal to perform the operating program. Then, when most terminals estimate to have completed operation, a higher value, such as 1 second, may be selected. At this time, even if the value is so high as to be out of the range that the terminal can normally tolerate, it is considered acceptable in order to achieve power saving.
Particularly, when the discontinuous transmission of the system information part is periodically performed, for example, every 1s, the neighboring cells synchronize their transmission of the specific system information part so that the transmission is not repeated, for example, if the transmission system information part is less than 100ms, cell a may transmit its system information at time points 1.0, 2.0, 3.0 seconds, …, etc., neighboring cell B transmits its system information at time points 1.1, 2.1, 3.1 seconds, etc., …, etc., and the accessory cell C transmits its system information at time points 1.4, 2.4, 3.4 seconds, …, etc. This is done so that the terminal performs the cell search procedure on multiple candidate cells (e.g., cells a, B, and C) at approximately the same time without experiencing the average or maximum delay of the candidate cells, respectively. For example, in the above figure, the system information of more than 10 cells can be received within about 1 second, while no system information part is transmitted alternately (steady), and in the worst case, it takes 10 seconds (e.g., delayed by 10 times the time of 1 second in the worst case) or 5 seconds on average (e.g., delayed by 10 times the time of 0.5 seconds in the average). Cells, especially in the same PLMN or a group of cooperating PLMNs, can benefit from this approach.
2. Triggering transmission of system information through an event, multiple events, and/or a combination of eventsIn one case, the terminal needs system information of a specific cell for operation, and the network and the specific cell are not aware of the terminal's needs. In other cases, the network and/or cell may be aware of and/or predict the needs of the terminal and/or may make a prediction of the need for a terminal for a particular system information part, and thus, in different embodiments, the trigger to send the system information part may comprise an indirect (implicit) or direct (explicit) trigger.
Indirectly triggering transmission of system information part
For example, when a terminal establishes a data session through a cell (typically the cell in which the terminal resides), the network and in particular the cell involved in the data session predicts that the terminal requires an additional portion of system information. For example, the terminal needs to specify measurement criteria on other cells as well as parameters of reporting criteria (e.g., in so-called handover "events", such as events where the signal level of the serving cell falls to a predetermined threshold and/or the signal level of a neighbor cell exceeds a predetermined range of the signal level of the serving cell, which may be positive or negative). In this case, the system information portion may be transmitted by the cell immediately after the session is established by the cell, which can result in greater energy savings than would normally be the case if the system information portion were substantially always repeatedly transmitted.
In another embodiment, the cell may utilize a time delay, such as 10 seconds, between the first trigger having been received (e.g., session establishment is completed through the cell) and the sending of the relevant system information part (e.g., the system information part that may be needed by the terminal). Other terminals that have established sessions through the same cell (one trigger for each can be considered) within the delay time may also receive the same portion of system information, which may ease the burden of the cell sending the same information multiple times.
Preferably, the delay value should not exceed a predetermined value corresponding to the maximum delay that is normally acceptable in view of the terminal, such as 15 seconds. Thus, when a plurality of terminals establish a session within the delay time, the system information portion is transmitted once to be notified to the terminals.
Those skilled in the art will recognize that it may be beneficial to apply deferred transmission only if other triggers related to the system information portion (e.g., one or more additional session setups) are predictable within a delay time. When the trigger rate (e.g., session establishment) is low, e.g., less than one session is established per delay time, the delay may have a small or even zero value.
The delayed transmission of the trigger system information portion may be combined with the reduced power selection transmission described in detail below. The reduced power setting should correspond to the most distant terminal in a group of terminals that complete session establishment within a certain delay time based on path loss.
Another example is a cell configured as multiple RACH channels, a common RACH channel (e.g., one predetermined RACH channel configured as all cells in the network or at least as many cells of the area) and one or more RACH channels configured for each cell. A terminal that has not received a RACH channel configured for a specific cell may directly issue a first request through a common RACH channel of the cell. The request may be processed or discarded by the cell, depending on the system configuration and the load of the cell. The cell that receives the RACH request through the common RACH channel considers this as an event that triggers transmission of a system information part related to the RACH channel configuration, and the subsequent request of the terminal can be directly addressed to any one of the RACH channels configured by the respective cells. This does not apply only to the particular terminal sending the request; other terminals that do not make a request within the cell may also receive the RACH configuration system information part of the cell that was transmitted due to the RACH request of a particular terminal.
Note that in this case, there is not much benefit from applying the delay described above, nor is there any benefit from applying the reduced power option. The RACH is configured as a substantially full power, non-delayed transmission, and may also be a plurality of terminals for monitoring a cell system information channel through a single transmission. The application of the power reduction selection depends on the estimated or predicted number of terminals in its coverage area of the cell, e.g., applying the power reduction selection at off-peak times and not applying the power reduction selection at peak times.
Direct trigger sending system information part
According to an embodiment of the present invention, when discovering that a specific system information part is needed by itself, the terminal may send a system information part request to the cell. Such a request is not available in conventional networks but is a request specifically designated for a specific purpose, which is performed, for example, similar to a RACH request. In another embodiment, the system information part request allows the terminal to specify which of the system information part or parts of the multiple system information it requests. In response to receiving a direct request, the cell may send a requested portion of system information, which may be received by the requesting terminal and other terminals listening to the cell's system information channel.
In embodiments, the cell may also consider the direct request as an indirect request, sending an additional system information part that is not specified in the direct request. This may be the case if the cell predicts based on experience that the additional system information part is important and/or will be requested later. This embodiment is particularly useful if the direct system information part request does not allow multiple system information parts to be requested.
Note that in this case, there is not much benefit from applying the delay described above, nor from applying the reduced power selection. The terminal requesting no-delay transmission of the system information part or substantially the full-power part may also be a terminal for multiple listening cell system information channels by a single transmission. The application of the power reduction selection depends on the estimated or predicted number of terminals in its coverage area of the cell, e.g., applying the power reduction selection at off-peak times and not applying the power reduction selection at peak times.
Fig. 5 provides an example of sending system information in response to an indirect or direct trigger. The cell is configured to repeatedly transmit signals, such as signal 20 in fig. 5, including system information blocks M, S1 and S2 similar to those described in fig. 4, followed by a time interval t2 in which no system information is transmitted. The repeatedly transmitted signal 20 is shown as signal 21 in fig. 5. Further, the cell may receive a trigger, either indirect or direct as described above, to send a system information block S3, in response to which the requested block S3 is sent to be received by (at least) the requesting terminal. This is shown in the signal 22 of FIG. 5, which schematically depicts the occurrence of two different triggers requesting the system information block S3, the first trigger being denoted "tr (S3) -1" and the second trigger being denoted "tr (S3) -2". Alternatively, the cell may wait a predetermined delay time Td after receiving the trigger before sending the requested information. This is depicted as signal 23 in fig. 5, with a delay time Td occurring after the first trigger, shown as "tr (S3) -1". As shown in fig. 5, three other triggers requesting the system information block S3 are then received by the cell during the delay time Td, but these triggers need not be taken care of since the cell has already scheduled the system information block S3 to be transmitted when the delay time Td expires. Fig. 5 depicts block S3 as being transmitted upon expiration of the delay time Td. Thereafter, the cell receives another trigger requesting the system information block S3, as shown by the fifth trigger "tr (S3) -5". The cell waits for a predetermined delay time Td before transmitting the requested block S3 (the second time the requested block S3 is transmitted not shown in fig. 5).
3. Transmitting system information with reduced power
The transmission power for transmitting the broadcast signal from the cell is mainly selected so that the farthest terminal, considering the path loss, is the most likely cell edge to reliably receive the broadcast information. According to an embodiment of the present invention, the cell may select transmission system information or a system information part with reduced power for power saving, for example, when the cell estimates that a terminal receiving the system information is closer than a farthest cell edge based on path loss. The power used to transmit the system information portion from the cell to a particular terminal may be estimated from the power setting employed in communication between the cell and the terminal over a dedicated channel on which the cell primarily controls the transmission power to be only sufficient for terminals on the dedicated channel to be able to receive. For transmitting system information to a terminal over a common channel, the cell may choose to use a higher power setting than the transmit power in the dedicated channel, which may increase the probability that system information is received in one transmission over the common channel, e.g., in most cases, without requesting that system information or part of the system information be transmitted again.
If a dedicated channel is not established between the cell and the terminal, the cell can estimate an appropriate transmission power for transmitting system information through a common channel of a RACH request received from the terminal. Such a RACH request may include a power indication in the RACH request transmitted by the terminal. And evaluating the power for receiving the RACH request, wherein the cell can determine the road stiffness loss experienced by the RACH request according to the difference between the transmitting power of the terminal and the receiving power of the cell. The cell uses this information and the fact that the uplink and downlink direction path losses are substantially the same to estimate the appropriate transmit power for transmitting the system information to the terminal over the common channel.
Yet another way to estimate the appropriate transmit power for the cell to transmit system information to the terminal is based on the power at which the terminal receives signals from the cell. Such measurements may be performed, for example, by cell reselected and/or handed over terminals. This information is primarily intended to be provided to the network, which may provide relevant parts of the information to the cell that is expected to send system information to the terminal, via different cells, or alternatively the terminal may provide measurement information directly to the cell.
When a cell simultaneously transmits system information or part of the system information to a plurality of terminals, the power reduction to be used may be determined by the most distant terminal among the plurality of terminals based on path loss.
4. Transmitting system information or system information portions (e.g. only delta portions) using reduced power
For example, when the terminal performs handover from one cell to a new cell, the terminal needs to be notified of a neighbor list (neighbor list) of the new cell. Typically, each cell sends its neighbor list, however, the old and new cells may share some neighbors so that the entire neighbor cell list, which contains duplicate information, is sent to the terminal for handover. According to an embodiment of the invention, instead of transmitting the entire neighbor cell list, the cell (old or new) transmits only the difference or delta part of the two lists. The delta portion transmitted by such a new cell contains information indicating the old cell ID11, ID12 …, etc. that should be deleted and the new cell ID21, ID22 …, etc. that should be added. The delta lists for multiple terminals may be combined in a single transmission. This may occur if the terminal that is handed over to the new cell originates from a different old cell, for example because the terminal ignores the delete command of the cell number that is not already in the terminal's neighbor cell list and ignores the add command of the cell number that is already in the terminal's neighbor cell list.
The new cell monitors the switching rate of the cell and the switching rate of the old cell, and makes a system information transmission strategy which is considered or evaluated by the cell to realize the maximum resource efficiency.
This method can also be used for many other parameters, such as handover parameter settings, which are typically assigned by system information, which have the same value in many cells of the network. For example, if a handover is made from an old cell to a new cell, where at least some of the specific parameters have the same value (e.g., handover settings) in both cells, the new cell may limit the transmission of these specific parameters in the system information. In other words, the difference (delta) between these specific parameters (parameter values) between the new cell and the old cell is 0, and in other cases, if a handover is made from another old cell to the new cell, where some specific parameters (such as handover settings) are different from those in the old cell, the new cell will send at least these parameters in its system information, so that the terminal can obtain to apply these parameters related to the new cell (e.g. by replacing old parameter values with new parameter values or adding new parameters).
5. Transmitting system information over dedicated channels
A fifth way of improving the energy efficiency of distributing system information comprises transmitting system information or part of it to specific terminals via dedicated channels, in addition to not using a common broadcast channel and transmitting system information to all terminals that may be present in the cell coverage area.
This scheme cannot be used for all system information parts or all system information components, e.g., it is not used for specific system information parts that require a request or establishment of a dedicated channel. Also, it is not used for the system information part or system information component that is mainly used for cell search. The additional expense (terminal and network) of establishing a dedicated channel for receiving the system information portion is then greater than the benefit obtained by using a dedicated channel instead of a broadcast or common channel.
However, if multiple terminals receive system information or system information portions and when the system information is not available prior to system information transmission, it is more efficient to perform system information allocation via broadcast or common channels. For example, it may be more efficient to notify ten terminals simultaneously in a single system information transmission than to notify only a single terminal. However, for such transmission, the farthest target terminal considering the path loss can be surely transmitted with high transmission power. If only a few terminals receive the information to be transmitted, the energy efficiency of the transmission is in doubt. If only a single terminal receives the information to be transmitted, the manner in which the information is provided is inefficiently. If no terminal receives the information thus transmitted, the transmission energy is wasted.
Moreover, with the trend of smaller and smaller cells, from a macro cell to a micro, pico or pico cell, it becomes increasingly impossible for multiple terminals to transmit the same portion of system information over a broadcast or common channel.
Thus, according to one embodiment of the invention, a cell is configured to transmit at least some of the system information portions over a dedicated channel from the cell to a particular terminal. Since the dedicated channel has power control, it may be more energy efficient to transmit quantitative data to a single terminal through the dedicated channel. Moreover, the dedicated channel works mainly in both directions, in the downlink direction from cell to terminal and in the uplink direction from terminal to cell, so that erroneous reception of system information parts or system information components can be corrected quickly and efficiently by the request sent by the terminal. Furthermore, the use of dedicated channels is well suited for terminal triggered cells, such as direct triggering, sending system information or part of system information and only the part of system information or system information components actually needed and requested by the terminal, including the use of "difference-only" or "delta" options as described above.
In various implementations, not all combinations of the five power saving approaches described above are equally applicable and/or useful, and other combinations may be easier. For example, transmitting system information to a terminal using a dedicated channel (option #5 above) may be better used in combination with transmitting only delta (option #4 above) and/or using indirect and/or direct triggering (option #2 above). Also, the use of indirect and/or direct triggering (option #2 above) may be better used in conjunction with intermittent transmission (option #1 above), especially when the selected portion of the system information has a low repetition rate (e.g., t2 is much larger than t 1). Conversely, the use of discontinuous transmission (option #1 above) and the use of dedicated channels to transmit system information to the terminal (option #5 above) are not suitable for use in combination, and the reduced power (option #3 above) is also implicitly used in the dedicated channels.
System information modification and/or refresh (active)
A special case of allocating system information includes a cell update (e.g., modifying) a specific system information portion. The modified system information portion should be assigned to those terminals that previously received "outdated" system information and are still within the cell coverage area. This can be performed efficiently by broadcasting the modified system information part at least once.
The system information modification can be efficiently performed through a broadcast channel or a common channel as in the conventional information, especially for the power setting of the farthest terminal. System information notification may also be provided through a paging channel as in UMTS or through a MIB, which can listen on an almost continuous basis.
The system information modification mechanism can also be used to replace the conventional mechanism adopted by the system information validity timer (system information validity timer) in each terminal at present. According to embodiments of the present invention, instead of the terminal driving the validity timer, the cell may be configured to maintain a refreshed timer. When the refresh timing time of the cell expires, the cell declares a refresh, e.g. similar to a modification of the system information, and broadcasts the complete system information at least once, so that all terminals currently in the coverage area can refresh and/or check the existing system information part and the additional part and store the system information part that has been currently lost.
Schemes #2-4 description of the general System
Scenario #2-4 is used to describe the telecommunications system 30 in fig. 6. As shown in fig. 6, a telecommunication system 30, in particular a cellular radio access telecommunication system, according to an embodiment of the present invention comprises at least a large area cell 32 and small area cells 33 and 34. A user terminal 35 is also shown in fig. 6, for clarity only the most relevant telecommunication system components are shown in fig. 6, other components may not be shown in fig. 6, but are also present and within the scope of the invention. The "other components" herein include, for example, additional small area cells, additional large area cells, additional terminals, even network nodes such as management entities and further components of the telecommunication system, and backhaul links between each cell and the telecommunication system and/or each other.
Each of the large area cell 32, the small area cells 33,34, and the terminal 35 will be explained below. A more detailed functional description of these components is discussed in different scenarios following this general description, respectively.
The large area cell 32 is a large area cell for enabling at least the terminal 35 to camp on the large area cell 32 and paging the terminal 35 in a conventional manner in the art. The large area cell 32 is also configured to receive a service request message from the terminal 35 indicating that a data connection needs to be established at the terminal 35 with one of the small area cells supporting wireless traffic (e.g., wireless exchange of user data), which is not shown in fig. 6. Although the large area cell 32 is not primarily intended to carry wireless user data for reception/transmission to the terminal 35, it is not excluded that other signaling than paging or some user data traffic is carried through the large area cell 32, such as low bit rate traffic (e.g., voice telephony) for all or part of a data session (telephone).
The large area cell 32 is mainly used to cover a large geographical area with a smaller code rate than the small area cells 33 and 34. The geographical area in which an idle terminal selects a large area cell to camp is referred to as the coverage area of the large area cell. In a suitably sized cell, terminals within the area are also typically able to successfully receive system information and signaling messages (e.g., paging messages) from a large area cell. This also applies to the opposite direction, e.g. when a terminal camping in a large area cell sends a signaling message (e.g. a service request message) to the large area cell in which it is camping, the large area cell is usually also able to successfully receive the message. In the radio access network coverage area, at least one large area cell (large area cell 32 in fig. 6) is able to exchange signaling messages with the terminal, assuming it is in a fully operational or "always on" state. In the simplest embodiment, this means that the large area cell 32 is always fully operational (on). In other embodiments, the energy saving option for large area cells may be applied on large area cells 32, meaning that large area cells will not necessarily always be in an "on" state.
The terminal 35 is a terminal operated by an actual human user, such as a mobile phone that the user can make a voice call or browse a network, but may also be a smartphone or a data center terminal (a notebook computer or a tablet computer) that is operated without human intervention (sending/receiving an email), and may also be an MTC (machine type communication) device, such as an intelligent electronic instrument, a car navigation device, or a video monitoring device.
The terminal 35 may be in an active mode or an idle mode, in use, when no user data exchange or traffic is available between the terminal 35 and the small- area cell 33 or 34, the terminal 35 is said to be in the idle mode. When the terminal is capable of exchanging data with at least one of the small- area cells 33,34, the terminal 35 is said to be in an active state. It is noted that the idle mode and active mode concepts are equivalent to the meaning of words in standard conventional networks, and as used herein, they need not be fully consistent with the standard definitions.
Also, the terminal 35 may support power saving options (e.g., power saving mode or operating mode, where the terminal consumes less power in power saving mode than in operating mode). Since the power saving mode differs from the active mode in the amount of power consumed by the terminal, whereas the idle mode differs from the active mode in that there is a wireless exchange of user data with a small area cell, the terminal may be in the active mode but still an idle terminal (or a terminal in the active mode may be in the active mode). Also, a terminal in a power saving mode is either active or idle depending on whether the terminal supports wireless exchange of user data with at least one small area cell. However, the most common situation is that an idle terminal in power saving mode is "woken up" to perform some function to cause a data connection to be established with at least one small area cell, after which the terminal becomes "active" (active) mode. Since embodiments of the present invention handle terminal-related system information allocation, the following description mainly distinguishes between idle and active modes of a terminal.
The idle mode terminal 35 is deemed to be at least "camped" in the large area cell 32, which may be implemented in a conventional manner. For example, the large area cell may broadcast a pilot signal (pilot signal) or a beacon signal (beacon signal), which the terminal 35 can receive and then select or reselect the camping large area cell using information contained in the received signal. In fig. 6, the signals transmitted by the large area cell 32 and received by the terminal 35 are represented by solid arrows from the large area cell 32 to the terminal 35. In an embodiment, the terminal 35 is able to inform the network of a change of its location area/routing area in order to facilitate the paging function of the large area cell 32, not shown in fig. 6.
The small- area cells 33 and 34 are mainly used for receiving/transmitting user data traffic of the terminals via a data connection established for that purpose, e.g. via dedicated channels. However, this does not preclude other information and/or signaling from being transmitted over one or more small-area cells.
Each of the small area cells 33 and 34 is mainly used to cover a smaller area with a high code rate, which is the opposite of the large area cell 32. In a typical deployment scenario, the area that may be covered by a nearby small area cell is an important overlap region. At least one of the small area cells 33,34 may be considered to be capable of providing coverage in the coverage area of the radio access network. Small area cells are fully operational only when needed and to some extent, in other words "normally closed". It is assumed that the small area cell supports at least one energy saving modality, such as energy saving mode or standby mode. Thus far, the embodiment shown in fig. 6 describes that the small-area cell 33 is a small-area cell in the energy saving mode (indicated by white triangles in fig. 6), and the small-area cell 34 is a small-area cell in the active mode (indicated by black triangles in fig. 6). In fig. 6, signals transmitted by the active small-area cell 34 and received by the terminal 35 are represented by solid arrows, while possible signals transmitted by the small-area cell 33 in the power saving mode and received by the terminal 35 are represented by dashed arrows.
Each of the terminal 35, the large area cell 32 and the small area cells 33,34 may comprise at least one or more communication interfaces for transmitting and receiving information, a memory unit for storing data (possibly received at the communication interfaces), and a processor for processing data and possibly running a computer program, the communication interfaces, the processor and the memory unit being suitably configured to perform the functions described herein.
Since energy efficient networks in this context differ from conventional cellular systems in that a terminal requires both large area cells and small area cells for communication, at least three different configurations of the terminal 35 are envisaged for receiving signals from and, where appropriate, transmitting signals to a cell of these cell types, in accordance with embodiments of the present invention.
A first configuration of the terminal 35, denoted "configuration (i)" below, envisages that the active terminal can support both radio interfaces-a large area cell radio interface for communicating with a large area cell 32 (and possibly other large area cells not shown in fig. 6) and a small area cell radio interface for communicating with small area cells 33,34 (and possibly other small area cells not shown in fig. 6). Those skilled in the art will appreciate that this configuration involves a more complex structure than a terminal with only a single radio interface. Such a terminal may, at least in some aspects, require only a large area cell radio receiver, such that the terminal can receive information from a large area cell over a large area cell radio interface, but the terminal need not have the capability to transmit information to the large area cell. In other embodiments (e.g., exchanging signaling information with a large area cell), such terminals also require a large area cell radio transmitter to enable the terminal to send information to the large area cell. Since only a low code rate is required for signaling information exchange with a large area cell, the additional complexity, cost and energy consumption of maintaining a large area cell radio interface can be kept low. Terminals 35 in the active mode configuration (i) may also receive signals from the large area cell 32 and/or exchange data with the large area cell 32 at any time.
A second configuration of the terminal 35, denoted "configuration (ii)" below, envisages that the terminal in active mode supports two wireless interfaces: the large area cell radio interface for large area cells and the small area cell radio interface for small area cells operate in a fast alternating mode of operation, i.e. in a time division mode. In other words, such a terminal enables a large area cell radio interface for one period of time and a small area cell radio interface for another period of time. When the terminal 35 of configuration (ii) is in active mode and does exchange data with the small-area cell 34, it is envisaged that the small-area cell radio interface is enabled for a longer period of time, and it is further envisaged that the data exchange with the small-area cell 34 is interrupted for a short time which does not have a detrimental effect on the terminal user, e.g. for a fraction of time less than 1s, e.g. 100 ms. The terminal of configuration (ii) may also be in active mode or may perform a reconfiguration of the radio interface from the small-area cell radio interface to the large-area cell radio interface and then receive signals from and/or exchange data with the large-area cell at any time but only for a relatively short period of time (e.g. 100ms) before restoring its radio interface configuration to the small-area cell radio interface. In this manner, a quasi-synchronous mode of operation may be achieved. In an embodiment, the terminal may reconfigure its radio interface to the large area cell and the small area cell may operate to synchronize the user data sent to the terminal to another terminal, to the extent that the small area cell does not send user data to a particular terminal (and/or send system information to the particular terminal and possibly to other terminals) during the time that the terminal configures its radio interface for receiving data from the large area cell. Such an embodiment may enable avoiding a small area cell from inefficiently transmitting user data to the terminal, thereby wasting small area cell resources. Moreover, the terminal is not frequently configured with a large-area cell radio interface (a small-area cell radio interface cannot be used), and the total time for starting the large-area cell radio interface of the terminal only occupies a relatively small part of time.
A third possible configuration of the terminal 35, denoted in the following "configuration (iii)", envisages that the activated terminal alternatively supports two radio interfaces (one for large area cells and one for small area cells), but not a fast alternating (continuous) operating mode as described in configuration (ii). For example, the quasi-synchronous mode of operation as described in configuration (ii) is not employed because it is considered unnecessary and/or because fast configuration is not supported in execution, for example if reconfiguring the radio interface requires more time, e.g., more than 1 second, than limited "fast". A terminal of the configuration structure (iii) is deemed to be capable of configuring its radio interface to exchange user data with a small area cell for a period of time. In this way, the exchange of user data is performed at the maximum rate possible without short interruptions as in configuration (ii). It follows that, depending on the configuration structure (iii), an active terminal will not be able to check whether it is still within the coverage area of the same large area cell at the time of data session set-up. Moreover, when the activated terminal is still in the coverage area of the same large-area cell, the system information modification of the large-area cell is not notified. Therefore, after the terminal exchanges data through the small-area cell and reconfigures its radio interface to the large-area cell, a cell search procedure must be performed and large-area cell system information must be obtained. Various methods known to those skilled in the art may remedy or at least alleviate this problem in order not to lose, for example, an incoming call or paging message before the cell search procedure is completed and sufficient system information is obtained.
Depending on the configuration (i), (ii) and (iii), the large area cell radio interface and the small area cell radio interface may be two separate physical radio interfaces with separate RF front ends, or share the same physical radio interface (as in the case where the large area cell and the small area cell operate in the same frequency band but with different carriers). In the latter case, the "small area cell radio interface" and the "large area cell radio interface" differ only in the "soft" configuration of the physical radio interface. For configuration architectures (ii) and (iii), a single physical radio interface is sufficient, i.e. either enabled as a large area cell radio interface (with the small area cell radio interface disabled) or enabled as a small area cell radio interface (with the large area cell radio interface disabled).
As used herein, the term "active" of a cell type (small area cell, large area cell) that activates or deactivates a small area cell or large area cell radio interface generally describes that the interface is capable of receiving signals from the cell and supporting data exchange with the cell, including any type of data such as user data, signaling data, network control messages, etc., while the term "inactive" generally describes that the interface is not capable of receiving signals from the cell and is not capable of supporting data exchange with the cell. Those skilled in the art will recognize that there are a variety of ways in which the interface may be "deactivated". For example, in one extreme embodiment, the deactivated wireless interface may be a wireless interface that is completely turned off, with no power being provided to the relevant portions of the electronic components of the interface. However, in the other extreme, the wireless interface is considered "off" when it is not in use, even though the interface itself is physically fully open and operational. The latter embodiment has a great advantage in that the time required to re-enable the interface will be small when re-enabling is required, since there is no or little delay in making the disabled interface ready for use when re-enabling is required. Various other embodiments of how to disable the wireless interface between the two-pole embodiments are available to those skilled in the art and are within the scope of the present invention.
Fig. 7 is a schematic diagram of a large area cell and multiple small area cell coverage areas in a telecommunications network, in accordance with one embodiment of the present invention. As shown in fig. 7, a large area cell 42, which may be considered the large area cell 32 in fig. 6, has a relatively large coverage area, shown by the dashed circle 43. Each of the plurality of small area cells can also be displayed as a triangle, such as triangle 44, which can be considered as small area cells 33,34 in fig. 6. The small area cells 44 have different, relatively small coverage areas, shown by solid circles, such as circle 45. Fig. 7 also shows an idle mode terminal 46 and an active mode terminal 47 (the active mode terminal is indicated as a black box terminal). Each of terminals 46 and 47 is terminal 35 in fig. 6, which is located within one or more coverage areas 45. Idle mode terminals 46 within the coverage area 43 of the large area cell 42 are said to be camped on the cell 42. A small area cell 44 with a footprint 45 shown in white is used to describe a small area cell in power saving mode and a small area cell 44 with a footprint 45 shown in grey shading is used to describe a small area cell in active mode, with which one or more active terminals 47 may engage in a data session. Of course, in other embodiments, the coverage areas 43 and 45 need not be circular, nor need they be omnidirectional sectors around the base station (cell) location.
Returning to fig. 6, a typical example of the behavior of a terminal 35 in an energy efficient network according to an embodiment of the present invention is as follows. When the terminal 35 does not need to exchange user data with the network (e.g., an idle terminal), it will camp on the large area cell 32 in the same manner as an idle terminal would camp on a cell in a conventional network. When the terminal 35 needs to exchange user data with the network (e.g. needs to enter active mode), it establishes a data session with a suitable small-area cell in the network, such as the small-area cell 34 shown in fig. 6. For maximum energy efficiency, a suitable small-area cell may have previously been deactivated (e.g., may have been disconnected or may have entered a power-saving state) and may need to be activated (e.g., awakened) to support a data session. When a data session is established, the terminal may exchange user data (and possibly also signaling) through/with the small-area cell 34, e.g., over a dedicated channel. The data session ends when the and active terminal 35 no longer needs to exchange further user data with the network. For maximum energy efficiency, small-area cell 34 may not be activated (e.g., may be off or enter a power saving state) if the small-area cell has no or only little traffic (the latter case occurring after transferring the remaining session to another small-area cell). The terminal 35 re-enters idle mode and camps on a large area cell, which may be the same large area cell (e.g., large area cell 32) that resided before establishing the data session, or a different large area cell if the terminal moves into the coverage area of another large area cell.
Scheme # 2: large area cell is allocated with large area cell system information and small area cell is allocated Area cell system information
As shown in fig. 6 and 7 and described above, the terminal 35 is initially assumed to be an active terminal for exchanging data with the small-area cell 34 via a data connection established between the terminal 35 and the small-area cell 34, such as via a dedicated channel. The embodiment of scheme #2 solves the problem that the terminal 35 obtains small area cell system information including at least system information related to the small area cell 34 and large area cell system information related to the large area cell 32, and possibly also system information related to other small area cells and other large area cells in the network 30, which system information is related to the terminal 35.
The implementation of this solution is based on the following idea: the large area cell 32 transmits its large area cell system information, the small area cell 34 transmits its small area cell system information, and the small area cell radio interface and the large area cell radio interface of the terminal 35 configured with structure (ii) can be alternately enabled in a time division multiplexing mode, as shown in fig. 8. The large area cell and the small area cell may transmit their respective system information, as shown in fig. 9, the small area cell 34 transmitting its system information to the respective active terminal 35 via a broadcast channel 51 indicated as a grey triangle and/or via dedicated channels 52,53 indicated as double-headed arrows, and the large area cell 32 transmitting its system information via a broadcast channel 54 indicated as a dashed triangle. When the terminal 35 is in idle mode, the terminal 35 is configured to receive the large area cell system information transmitted by the large area cell 32 in which it is camped over the large area cell radio interface enabled for such idle terminals. The small area cell radio interface is not enabled. When the terminal 35 is in the active mode, data exchange is performed with the small-area cell 34 through the established data connection, and for a long time, the small-area cell radio interface of the terminal 35 is enabled and the large-area cell radio interface is disabled. At this time, the terminal 35 may exchange user data with the small-area cell 34, may receive other signals including system information from the small-area cell 34, and may receive signals including system information from other small-area cells of the network 30. In the rest of the time, the large-area cell radio interface of the terminal 35 is activated, and the small-area cell radio interface is deactivated. At this time, the terminal 35 may receive a signal including system information from the large area cell 32 and possibly support a signaling connection through the large area cell 32, and the terminal 35 may also receive a signal including system information from other large area cells of the network 30. In this manner, a terminal in active mode and exchanging data with a small-area cell over a small-area cell radio interface may temporarily interrupt or suspend user data exchange with the small-area cell and enable the large-area cell radio interface at one or more particular times when the terminal desires the large-area cell or cells to send their system information to the terminal so that the terminal may receive the large-area cell system information sent by the large-area cell or cells. Such a terminal may receive small-area cell system information from one or more small-area cells when the small-area cell radio interface is enabled.
The terminal 35 configured according to the above configuration structure (i) has two radio interfaces operating simultaneously, and when it operates in a "parallel" manner, various methods in scheme #1 can be used. Embodiments of scenario #1 may be adapted to allocate system information over both large area cells and small area cells, which system information is received by terminal 35 over respective mutually independent wireless interfaces.
Fig. 10 is a flowchart of method steps provided in accordance with an embodiment of the present invention for obtaining system information related to one or more small-area cells and system information related to one or more large-area cells. Although the method steps are described in conjunction with fig. 6, one skilled in the art will appreciate that any system that performs the method steps in any order is within the scope of the present invention.
The method begins at step 61 with the terminal 35 in an active mode and the small-area cell radio interface of the terminal 35 enabled. The terminal 35 receives at least a portion of the small-area cell system information related to the small-area cell 34 from the small-area cell 34 through the small-area cell radio interface of the terminal (of course, the terminal 35 may exchange data with the small-area cell 34). Terminal 35 also receives small-area cell system information from other small-area cells associated with terminal 35. In step 62, the terminal 35 activates the large area cell radio interface during the one or more LA times to receive large area cell system information of the large area cell 32 over the activated large area cell radio interface in step 63. A terminal 35 configured according to configuration (ii) has two fast alternating radio interfaces, preferably large area cells 32 only transmitting their system information for a short period of time, e.g. 100ms (or less). Another preferred method is that the macro cell transmits its system information within a predetermined time period or starts to transmit its system information at least at a predetermined moment in time, e.g. the macro cell system information transmission is repeated cyclically for 100ms per second. The mode of sending the large area cell system information is set either by the large area cell 32 itself or by some other network entity such as a network administration or OAM (operation, administration and maintenance) entity and/or a synchronization entity. When an indication is provided to the terminal 35 that a transmission of the large area cell system information has occurred, the activated terminal can reconfigure its radio interface to the large area cell to receive the large area cell system information, such as just before the large area cell system information is expected to begin transmission, optionally also performing other large area cell related operations, such as signal strength measurements to assess whether the terminal 35 is still within the coverage area of the large area cell 32. When this is done, the terminal 35 may reconfigure its radio interface to a small-area cell (it may also continue to exchange e.g. user data through the small-area cell 34).
In optional step 64, the terminal 35 may configure one or more settings based at least in part on the received small-area cell system information and/or the received large-area cell system information. In an embodiment, the terminal 35 may be configured to store at least a portion of the received small-area cell and large-area cell system information for later use. In this regard, it should be noted that the small-area cell system information sent by the small-area cell 34 is not limited to only being related to the small-area cell 34, but may also be related to one or more other active or inactive small-area cells in the network, such as a neighboring small-area cell, e.g., the small-area cell 33 shown in fig. 6. The terminal 35 also receives and stores small-area cell system information relating to another small-area cell, rather than the only serving small-area cell 34, which has benefits, such as in the case of handover to a different, e.g., neighboring small-area cell. In this way, the system information or a major part thereof related to the new small-area cell can already be obtained by the terminal before the handover is performed, but not after the handover. Such "early" acquisition of system information relating to another non-serving cell facilitates faster handover completion than the main system information in the usual method can only be obtained after handover is performed. Fast execution of the handover is particularly advantageous in situations where the dwell time in a particular cell, e.g. a small area cell, is relatively short due to the small size of the cell, mainly the small area cell and the high mobility of the terminal. This "advance" acquisition of system information about another small-area cell, rather than just the serving small-area cell, is also very beneficial in energy-efficient networks where the target small-area cell for handover is still inactive (as in small-area cell 33 in fig. 6) and needs to be reactivated before it is fully operational. During the reactivation time, the small-area cell is not yet fully able to transmit its small-area cell system information, so that the terminal 35 can effectively use the stored system information of the specific small-area cell to configure itself for handover. Also, although the advantages described above apply rarely to large area cells, the system information sent by a large area cell 32 is not limited to being related to only a large area cell 32, but may also be related to one or more other large area cells (not shown in fig. 9) in the network, such as neighboring large area cells. Similar benefits of storing system information apply to active terminals, saving large area cell system information, and returning to idle mode when user data exchange is complete. For example, when the terminal 35 is idle again, the terminal may apply the stored large area cell system information to configure its settings. In each case, it is preferable that the terminal can quickly check whether the stored system information of a specific cell (a small-area cell or a large-area cell) is still valid. This may be done in a conventional manner, such as by system information version numbering. Such version numbers are broadcast very frequently for broadcast system information, for system information provided over a dedicated channel the terminal sends an indication of the stored system information version number to the cell, which responds either with a confirmation that the version is still valid or with the latest version number, and provides the latest (valid) part of the system information part modified according to the version number indicated by the terminal. How the network 30 is configured to enable the terminals to obtain the small area cell and large area cell system information has a variety of ways, here as "very simple configuration", "more flexible configuration", and "most flexible configuration", which are described in detail below.
Very simple arrangement
In a very simple configuration, a small area cell, such as small area cell 34, is used to transmit user data to each of the active terminals 35, a small area cell is used only for times that do not overlap with the predetermined time period, a large area cell, such as large area cell 32, transmits large area cell system information, e.g., 100ms of large area cell 32 per second transmits large area cell system information, and 900ms of small area cell 34 per second transmits user data. In other words, the predetermined time for transmitting the large area cell system information is reserved to allow the terminal to receive and obtain the large area cell system information without allowing the user data to be received through the small area cell, thereby reducing the achievable throughput of the small area cell user data compared to 90% of the case where the user data is transmitted 100% of the time by the small area cell. The time at which the small area cell can transmit user data is now designated as the "first time" in this example, while the predetermined time at which the large area cell can transmit large area cell system information is designated as the "second time". Although the first and second times are configured not to overlap with each other, they need not be adjacent times (there may be gaps between them) due to the additional blank time used, for example, to allow for completion of reconfiguration of the terminal's radio interface and to allow for inaccuracy in the timing of both types of cells.
Since a small area cell may have more than one large area cell that partially overlaps the coverage area of the small area cell, the small area cell at a first time will need to consider the second time of each associated large area cell. To avoid further reducing the time share that a small area cell can efficiently utilize its first time (further reducing the achievable throughput), it is preferable that the large area cells synchronize their second times with each other such that their second times occur as overlapping as possible, e.g. substantially simultaneously. With the above example, the second time of 100ms per second is used substantially simultaneously with all large area cells associated with small area cells.
In this very simple configuration, there are two options for how the small area cell transmits system information. In a first option, the small-area cell may send the small-area cell system information during the second time (i.e., when no user data is being transmitted), possibly in the gap between the first and second times but not during the first time. In this option, the small-area cell system information is transmitted at a relatively high data rate, so that a large amount of small-area cell system information can be transmitted in a relatively short time, since the small-area cell does not require any transmission resources for user data during these times. In a second option, the small-area cell may transmit the small-area cell system information at any time, including at a first time, at a second time and/or within a gap. In such a further embodiment of the second option, the transmission rate of the small area cell system information may be set to a relatively high rate at the second time and possibly in the gap, e.g. relative to the rate in the first option. For both options, the small-area cell does not limit the time it receives user data from the terminal; the small-area cell may be received at any time when the terminal selects whether to send user data to the small-area cell. It is noted that when the system is configured to operate in TDD (time division duplex) mode, there are typically (possibly predetermined) time slots allocated for downlink transmission from the cell to the terminal, and other time slots allocated for uplink transmission from the terminal to the cell, although the above configuration must be adapted to allow TDD time slots to be allocated for downlink and uplink transmissions, respectively.
The large area cell may be used to send the large area cell system information to the active terminals only during the second time (not at the first time, and no longer in gaps). In an option, the large area cell may also send some large area cell system information outside the second time, e.g., system information not used for idle terminals and/or the same system information (partially) sent in a different format (e.g., low code rate, simple coding, etc.) to better match idle terminals. Data exchange through the large area cell, e.g. supporting dedicated signalling connections, and/or user data exchange through the large area cell may be performed at any time (of course, in the TDD case, the above-mentioned allocated time slots are taken into account).
In a network where multiple large area cells transmit their system information, in one embodiment, different large area cells may transmit their system information synchronously, substantially simultaneously, e.g., at some time within 100ms of time. The advantage of this implementation is that small-area cells do not need to distinguish between terminals and/or between large-area cells associated with terminals, and small-area cells only need to plan the free transmission time of single user data within 100 ms. A disadvantage of this implementation is that the terminal may only receive system information from a single large area cell in 100 ms. In another embodiment, different large area cells may be used to transmit their system information synchronously, e.g., substantially continuously over a 100ms period. In such an embodiment, the terminal has the advantage of being able to receive and obtain system information from multiple (e.g., two) large area cells in corresponding consecutive 100ms time slots, which implementation has the disadvantage of further reducing the achievable small area cell throughput rate of user data, possibly requiring each terminal (or at least each pair of large area cells) to plan the free transmission time of the small area cell.
In the first time, the active terminal which does not need any large area cell system information can keep configuring the wireless interface in the small area cell, and can send user data at any time, receive user data in the first time, and also receive small area cell system information in the second time (possibly in a gap). An active terminal that is to receive the large area cell system information may continue to transmit and/or receive user data for a first time. Then, when it is time for the first time end point, the terminal will reconfigure its radio interface to the large area cell (this is facilitated by the time gap), receive the large area cell system information, and reconfigure its radio interface to the small area cell no later than the second time end point (this is facilitated by the time gap again). Thereafter, the terminal transmits and/or receives user data through the small-area cell again in the next first time.
In this configuration, as previously described, the transmission of system information by the small-area cell and the large-area cell occurs in coordination, substantially simultaneously during the second time, while the transmission of the small-area cell system information may occur in the gap between the first and second times, particularly in the first option.
More flexible configuration
In this configuration, there is no predetermined repeating sequence of the first time and the second time.
The small-area cell sends the user data to the specific terminal continuously, or the small-area cell has interruption or pause in sending the user data, and in the downlink user data sending, the pause of the small-area cell user data sending is predetermined, clear, designated and/or ordered by the specific terminal to the small-area cell in advance. Thus, when the terminal requires free transmission time of user data of a small area cell, the terminal is enabled to have full control, such as receiving system information from one or more large area cells, evaluating signal levels of one or more large area cells, and/or contacting (e.g., exchanging signaling information with) one or more large area cells. This also allows a specific terminal and a specific occasion (occasion-specific) to measure the size of the free transmission time of the user data of the small-area cell. For example, a terminal performing a slow reconfiguration of its radio interface may require a longer free time for a small-area cell than another terminal performing a fast reconfiguration of its radio interface, or a terminal requiring only a particular system information portion that is in the vicinity of the desired transmission time for that particular system information portion may require 100ms than illustrated and a shorter free time for a small-area cell than another terminal that obtains full system information within 100 ms.
In this more flexible configuration, when a small-area cell interrupts its downlink user data transmission to a particular terminal, the small-area cell may continue to transmit user data to other terminals that have not explicitly been interrupted.
For small-area cell system information transmitted by a small-area cell, all options described according to the foregoing configuration are freely selectable without preference. For example, a small-area cell may be configured to transmit small-area cell system information in a conventional, nearly continuous, appropriate code rate manner. In another example, a small-area cell may be configured to transmit its small-area cell system information at a high code rate in short pulses.
The small-area cell may be configured to transmit user data at any time, and the terminal selects whether to transmit the user data to the small-area cell (of course, in the TDD case, the above allocated time slot needs to be considered).
The large area cell may send its large area cell system information in short bursts, but also preferably according to a predetermined schedule (e.g., periodicity) that is predetermined by the large area cell or other network node such as a network management entity or synchronization entity and can be known or detected by the terminal listening to the large area cell. In response to the above-described alternative "very simple configuration" of the macro cell, there is also an option in this configuration that the macro cell may also send some macro cell system information outside of the second time.
The exchange of data over the large area cell, for example in order to support a dedicated signalling connection and/or the exchange of some user data over the large area cell, may be performed at any time (of course, in the TDD case the above-mentioned allocated time slots are considered).
An active terminal that does not require any large area cell system information can keep its radio interface configured to a small area cell, can send user data at any time, can receive user data at any time, and can receive small area cell system information at any time (at least when small area cell system information is sent). An active terminal that requires large area cell system information first provides an indication to a small area cell having a data connection with the terminal when the small area cell should suspend (interrupt) its downlink transmission of user data for a particular terminal. For this purpose, the terminal provides an indication, for example, a single interrupt with a specific start time and end time, a single interrupt with a specific start time and interrupt elapsed time, or a plurality of interrupts arranged according to a cycle. The time at which the downlink user data transmission is suspended (interrupted) in the small area cell is different from the second time described in the "very simple configuration" in that in this more flexible configuration, such time is terminal-defined or terminal-specified and may never occur, may occur once or repeatedly (possibly over different times). After providing the indication to the small-area cell, the terminal continues to transmit and/or receive user data until the interruption time begins. At or after the start time, the terminal reconfigures its radio interface to the large area cell. The time assumption for doing so is known to the terminal and may take into account when to specify the downlink user data interruption start time to the small-area cell. A terminal with an enabled large area cell radio interface may receive the large area cell system information, or at least a portion related to the information, and reconfigure its radio interface back to the small area cell no later than the end time of the interruption. Similar to the time to reconfigure the terminal radio interface to the large area cell, the time to reconfigure the terminal radio interface to the small area cell is also assumed to be known to the terminal, also assuming that it takes into account when to assign the downlink user data interruption end time to the small area cell. The terminal may then retransmit and/or receive user data from the terminal's end time.
As described above, this configuration does not require cooperation of system information transmission by the small-area cell and the large-area cell. However, a terminal that needs to monitor the large area cell system information and cannot monitor the small area cell system information for that period of time (second time) will repeatedly and constantly lose all of the small area cell system information. This can occur if the small area cell system information is transmitted within a short burst time that coincides with the large area cell system information transmission time. Even if the small-area cell system information is transmitted substantially continuously, the terminal can repeatedly and always lose a specific part of the small-area cell system information. To avoid this, preferably, the small-area cell and the large-area cell may simultaneously transmit their respective system information such that the repetition rate of the transmission of the small-area cell system information is different from the repetition rate of the large-area cell system information. With this synchronization, the portion of the small-area cell system information that the terminal may lose will not be repeated and consistently the same portion of the small-area cell system information, but rather move along the small-area cell system information. This may be achieved, for example, by selecting a repetition time for the small area cell system information that corresponds to the (possibly short) time (e.g., the second elapsed time) elapsed for the large area cell system information transmission to the active terminal, or a shorter or longer repetition time for the large area cell system information. Alternatives are also possible, for example, in which case the terminal jumps for the second time, keeps its radio interface configured to the small-area cell for reception to obtain the small-area cell system information, or the terminal requests the small-area cell directly, for example via a dedicated channel for user data exchange, for example, and provides the specific small-area cell system information to the terminal again via a dedicated channel for user data exchange, in which case the options #2 and #5 using the scheme #1 are particularly useful.
In this configuration, since the small area cells have coverage areas at least partially overlapped by the coverage areas of the plurality of large area cells, there is no need for adjacent large area cells to synchronize their large area cell system information transmissions with each other, substantially simultaneously. The terminal may indicate and/or command the interruption of downlink user data transmission by the cell in response to the time at which its large area cell system information is transmitted by the large area cell (e.g., the particular large area cell that the terminal wishes to monitor), however, in embodiments, synchronized large area cell system information transmission can still be performed. This implementation is advantageous for the terminal since different outage times do not need to be assigned to different large area cells.
Most flexible configuration
This configuration is mainly in contrast to the "more flexible" configuration described above, where the start and termination of a small cell downlink user data interruption (e.g. suspension and resumption of downlink user data transmission) is specified by the active terminal at any time.
In one embodiment, the terminal transmits a command specifying no time point or a specific time point at which a future command is applied to suspend the small-area cell downlink user data transmission. The small-area cell receiving the command may interpret the command without a time indication as being at the current time, e.g., immediately or as early as possible. For example, upon receiving an immediate pause such a command, a small-area cell may be used to complete a block or user data frame as currently transmitted, and then stop further transmissions to the terminal. Upon receiving the immediate recovery command, the small-area cell may be used to immediately resume transmission to the terminal.
In another embodiment, the terminal may send a command to suspend the small-area cell downlink user data transmission at a specific time. A small-area cell receiving a specified time-out command may be used to interpret the command as that the transmission of the small-area cell to the terminal must be stopped at the specified time at the latest. The designated time resume command indicates that the small-area cell can resume transmission to the terminal from the designated time at the earliest.
Based on the designated time of suspension and recovery of the downlink transmission of the small-area cell at any time, the terminal is provided with additional flexibility, and the small-area cell transmission can be recovered as early as possible when the terminal performs the operation of the large-area cell without waiting for the termination of the system information transmission time of the large-area cell. Those skilled in the art can immediately realize how to adapt the above description to a more flexible configuration so that the start and termination of the small-area cell downlink user data transmission can be specified at any time, and therefore, for the sake of brevity, a description will not be repeated here.
Scheme # 3: large area cell allocation large area cell system information and small area cell system information in energy efficient network Information processing device
As shown in fig. 6 and 7 and described above, first, the terminal 35 is assumed to be an idle terminal that does not exchange user data through the small area cells 33,34 and that resides in the large area cell 32. The terminal 35 may also be activated by a data connection established between the terminal 35 and the small-area cell 34, for example by exchanging user data with the small-area cell 34 using a dedicated channel. The embodiment of scheme #3 solves the problem of the terminal 35 obtaining small area cell system information including at least system information related to the small area cell 34 and large area cell system information related to the large area cell 32, and possibly system information related to other small area cells and other large area cells related to the terminal 35 in the network 30.
Embodiments of this scheme are based on the idea that a large area cell, such as large area cell 32, may be used to transmit large area cell system information as well as small area cell system information for at least some of the small area cells that may be associated with terminals within the coverage area of the large area cell. Scheme #3 can be divided into two main embodiments, shown in FIGS. 11 and 12, respectively. In a first embodiment, the large area cell 32 transmits all system information to the terminals using a broadcast/common channel, and in a second embodiment, the large area cell 32 transmits at least some system information to the respective terminals using one or more dedicated signaling channels, which are described in detail below.
Using broadcast/common channels
Fig. 11 is a diagram illustrating an example of a large area cell providing a terminal with large area cell system information and small area cell system information according to an embodiment of the present invention. As in the embodiment of fig. 11, the large area cell 32 transmits its system information and system information of one or more small area cells associated with the terminal 35 via a broadcast channel 71. Idle terminals only need to enable their large area cell radio interface at least during the time that the large area cell system information broadcast channel is listened to. This enables the idle terminal to obtain all system information for the large area cell and all possible related small area cells within the coverage area of the large area cell. The idle terminal stores the obtained system information and keeps updating. The idle terminal also uses the stored system information of the particular small-area cell when establishing a data session with the particular small-area cell. Such operation of the terminal may be supported according to the above-described terminal configuration structures (i), (ii), and (iii).
Each active terminal that exchanges user data with the small-area cell 34 through the dedicated data channels 72,73, and 74 shown in fig. 11 may also be used to listen to the system information broadcast by the large-area cell 32. Terminal 35 may be used to listen for both large area cell and small area cell system information broadcast by large area cell 32 or periodically or upon receipt of a trigger.
For the embodiment of scenario #3 depicted in fig. 11, two terminal configuration architectures are conceivable.
Using the terminal configuration structure (i) described above, the active terminal may use the small-area cell radio interface to exchange user data with the small-area cell 34 continuously and/or when user data exchange is required. The terminal temporarily enables the macro cell radio interface for a relatively short period of time, e.g., periodically or upon receipt of a trigger, to listen for the macro cell system information broadcast by the macro cell 32. the broadcast channel 71 contains the macro cell and the small area cell system information. The advantage of this configuration is that user data exchange through a small area cell can continue uninterrupted. However, the terminal needs to support both radio interfaces simultaneously for at least a short time, which causes high hardware complexity.
Using the terminal configuration (ii) described above, the active terminal can alternate between wireless interfaces. The terminal enables its small-area cell radio interface for a longer time to support the exchange of user data with the small-area cell 34. While the large area cell radio interface is deactivated. To monitor the large area cell system information broadcast channel 71 containing large area cell and small area cell system information, the terminal only enables the large area cell radio interface for a short period of time. While the small area cell radio interface is deactivated.
In the broadcast channel 71, the small-area cell system information transmitted by the large-area cells 32 may be grouped in units of each small-area cell or each group of small-area cells. For energy efficient system information distribution, the large area cell 32 transmits the cell system information only when needed, e.g., only for the active or to-be-activated cell. To expedite the establishment of a data session through a small area cell that has not yet been activated, the large area cell 32 may be used to send system information for all small area cells, such as including an indication of the activation status of the small area cell. In this manner, terminals in idle mode and terminals in active mode are able to obtain, store and keep updating their respective large area cell and small area cell system information simply by listening to the large area cell broadcast channel. This approach speeds up the process of establishing a data session and the handover process from one small-area cell to another by activating the small-area cell, since the system information is available to the terminal even before the terminal needs the information.
To further expand the system information available to the terminal, the cell configuration in which the large area cell 32 allocates system information may be further expanded to system information relating to neighboring large area cells and/or system information relating to small area cells that are outside the coverage area of the large area cell 32 but close together.
A further improvement of the embodiment shown in fig. 11 is to provide the activation terminal with a trigger signal or a trigger message in order to focus the activation terminal on the user data exchange via the small-area cell 34 in case the relevant part of the system information is modified. Such a trigger signal or signal message may be sent by the network to the terminal over a dedicated connection or broadcast by one or more small-area cells in the network. The trigger may also optionally indicate which cell or cells the modification is associated with. A terminal receiving such a trigger signal or message can thus be informed of some modification of the system information part and the associated terminal obtaining the modified system information.
In an embodiment, the activation terminal interprets certain events as triggers, for example when the terminal performs a handover from an old small-area cell to a new small-area cell due to movement, and needs to obtain, update or check system information of the new small-area cell. Providing the trigger to the active terminal mitigates possible modifications of the active terminal regularly, e.g. periodically performing a listening to the large area cell broadcast channel, which is particularly advantageous for the terminal configuration structure (ii).
Although not most energy efficient compared to other solutions, the embodiment shown in fig. 11 also gives the advantage that the terminal can obtain system information for all small area cells within the large area cell coverage area and can store this information for later use. In this way, the terminal can apply the cell-related settings more quickly in the case where an idle terminal establishes a data session or an active terminal performs a handover from one small-area cell to another, than in the case where the terminal can only obtain most of the cell-system information when the session establishment or handover to the small-area cell is completed. This embodiment also enables a pre-allocation of small area cell system information to idle terminals, e.g. before a terminal establishes a data session, even if no small area cell is active in the neighbourhood of the idle terminal.
Using dedicated channels
An alternative to the above-described embodiment, to avoid consuming broadcast resources for the large area cell 32 to broadcast system information related to small cells, a dedicated signaling method may be used. This is depicted in fig. 12, which schematically illustrates the large area cell 32 transmitting its system information and system information of one or more small area cells associated with the idle terminal 35a over a broadcast channel 81, while providing the small area cell system information and/or the large area cell system information and modifications thereof to the active terminal 35b over a dedicated signaling channel 82.
In this scenario, optionally, when the session setup includes a dedicated signaling connection through the large area cell 32, the large area cell 32 may provide all relevant system information related to the small area cell selected to support the session through the dedicated signaling connection 82 at the time of the session setup.
Triggered by an event, e.g. when the terminal performs a handover from an old small-area cell to a new small-area cell, e.g. due to mobility, or the network modifies some system information, e.g. reconfigures system parameters of a small-area cell and/or a large-area cell, the dedicated signaling channel 82 through the large-area cell 32 may be used to send the modified system information to the active terminal 35 b.
For such an active terminal, two terminal configuration configurations are conceivable.
Using the terminal configuration structure (i) described above, the active terminal may use the small-area cell radio interface to exchange user data with the small-area cell 34 continuously and/or when user data exchange is required. To support a dedicated signaling connection 82 over a large area cell, to receive any modification (update) of the large area cell system information associated with the large area cell 32 or the small area cell system information associated with any small area cell 34, the terminal 35b temporarily, e.g., periodically or upon receipt of a trigger, activates the large area cell radio interface for a relatively short period of time. The advantage of this configuration is that user data exchange through the small area cell 34 can continue uninterrupted. However, the terminal 35b needs to support both wireless interfaces simultaneously for at least a short time, which causes high hardware complexity.
Using the terminal configuration (ii) described above, the active terminal can alternate between wireless interfaces. The terminal enables only its small-area cell radio interface for a longer time to support the exchange of user data with the small-area cell 34, while the terminal enables only the large-area cell radio interface for a shorter time to receive any modification (update) of the large-area cell system information related to the large-area cell 32 or the small-area cell system information related to any small-area cell 34.
The embodiment shown in fig. 12 is expected to be more energy efficient than the embodiment shown in fig. 11 due to the use of dedicated signaling connections. This embodiment also has advantages over other embodiments that involve energy efficient allocation of system information. For example, the entire connection between the network and the terminal may be lost, considering that the mobile terminal must frequently handover to different small area cells and there is a possibility of failure during each handover. In the case of frequent and error-prone handovers, it is very attractive to have a stable and unchanging signaling connection with the large area cell 32, by which failed handovers can be corrected quickly. It is also of interest to provide the modified small area cell system information part to the terminal over the large area cell signalling connection as described above. All additional savings are also related to dedicated connection applications, such as applying power control dedicated signalling connections and the possibility to provide the terminal with system information related only to small area cells. Given the path loss, having a larger distance between the terminal and the large area cell than between the terminal and the small area cell, typically, but not always, lower energy efficiency may be more important than the stability and reliability of the large area cell signaling connection.
Scheme # 4: system information of small-area cell allocated with large-area cell and system information of small-area cell in energy efficiency network
Similar to scenario #3, in this scenario, shown in fig. 6 and 7 and described above, terminal 35 is first assumed to be an idle terminal that does not exchange user data through small area cells 33,34 and resides in large area cell 32. The terminal 35 may also be activated, which exchanges user data with the small-area cell 34 via a data connection established between the terminal 35 and the small-area cell 34, e.g. via a dedicated channel. The embodiment of scheme #4 addresses the problem of the terminal 35 obtaining small area cell system information including at least system information related to the small area cell 34 and large area cell system information related to the large area cell 32, and possibly related system information of other small area cells and other large area cells in the network 30 related to the terminal 35.
Embodiments of this scheme are based on the idea that small area cells, such as small area cell 34, can be used to transmit small area cell system information and large area cell system information for at least some of the large area cells that may be relevant to terminals within the coverage area of the small area cell. Scheme #4 can be divided into two main embodiments, shown in figures 13 and 14, respectively. In the first embodiment, the small-area cell 34 transmits all system information to the terminal using a broadcast/common channel. In a second embodiment, which is described in more detail below, the small-area cell 34 transmits at least some of the system information to each terminal using a dedicated signaling channel connected to the active terminal.
Using broadcast/common channels
Fig. 13 is a diagram of a small-area cell providing a terminal with small-area cell system information and large-area cell system information according to an embodiment of the present invention. As in the embodiment of fig. 13, small-area cell 34 transmits its system information and system information of one or more large-area cells associated with active terminal 35b via broadcast channel 91 (shown as a grey triangle in fig. 13). Optionally, the small-area cell 34 also includes system information relating to neighboring small-area cells into the broadcast channel 91. As shown in fig. 13, small-area cell 34 also establishes data connections 92, 93, and 94 (e.g., via dedicated channels) with each active terminal 35 b.
In the case of a modification of the large area cell system information for the large area cell, the large area cell will notify all small area cells associated with the large area cell coverage area of the modification, shown by arrow 95 in fig. 13. Such notification may be provided, for example, over an access network interface like X2 of LTE. The small-area cell 34 receiving such notification then broadcasts a notification of the modified system information and a notification of the modified large-area cell system information over the broadcast channel 91. In the case where the small-area cell 34 also broadcasts system information of another (neighboring) small-area cell, the same applies to the modified system information of the neighboring small-area cell, as the other small-area cell is configured to notify the relevant (neighboring) small-area cell (not shown in fig. 13), and the small-area cell 34 will then broadcast a notification of the modified system information over the broadcast channel 91, along with a notification of the modified small-area cell system information related to the other small-area cell.
The active terminal 35b receiving the modified system information notification obtains the modified system information related to the large area cell and/or related to another small area cell through the broadcast channel 91 of the serving small area cell 34.
Since the distance between a small-area cell and a terminal is generally much shorter than the distance between a large-area cell and a terminal, the embodiment shown in fig. 13 is very attractive from the energy efficiency point of view. However, to support idle terminals 35a, at least some of the large area cell system information, such as the large area cell network, the large area cell identity, various parameters associated with the large area cell broadcast channel, the large area cell neighbor cell list, etc., needs to be transmitted by the large area cell 32 itself, as illustrated by the broadcast channel 96. Thus, the energy efficiency gains are mainly applied to the large area cell system information part, such as handover parameters, related to active terminals only.
In embodiments where the large area cell system information part associated with idle terminals may also be sent via the small area cell 34, this provides the advantage that the active terminal 35b can use this information available after the end of the data session to enable fast cell search and/or cell reselection. However, this embodiment also causes repeated transmission of the large-area cell system information, which may reduce the energy efficiency gain somewhat.
A small area cell broadcasting at least some of the large area cell system information of one or more large area cells with which it shares some coverage area has the further advantage of providing information to active terminals about the relevant large area cell without requiring the terminal to use its large area cell radio interface. For example, when a small area cell 34 broadcasts some system information to a single large area cell, an active terminal receiving that system information may conclude that it will almost certainly discover itself to re-camp in that particular large area cell when it ends the data session.
In another example, when small-area cell 34 is the small-area cell to which the active terminal is handed over, small-area cell 34 broadcasts some system information related to both large-area cells (already contacted large-area cell and "new" large-area cell), then the terminal may conclude that when it ends the data session, it will almost certainly find itself to make a re-camping selection among the only two main candidates. For the terminal configuration (i) or (ii) above, the sending of the large area cell system information of the two large area cells may trigger the terminal to perform the evaluation of the particular large area cell. The information in the terminal's large area cell neighbor cell list may even be omitted since the small area cell 34 provides more detailed information about the most relevant neighboring large area cells. Although providing all the system information of those large area cell(s) may not be most energy efficient from the narrow point of view of allocating large area cell system information, it is also of interest for terminals having a terminal configuration structure (ii), since this can significantly reduce the time required for activation of the large area cell radio interface, mainly at low code rates. For the terminal configuration structure (iii) described above, the terminal need only obtain the large area cell system information of its small area cell allocation for ending the data session. The number of large area cells, e.g., one, two or three large area cells, to which system information is allocated by a given small area cell may be limited, thus speeding up the cell search and/or cell reselection process for the terminal since it has already obtained relevant system information for these large area cells.
Using dedicated channels
An alternative to the above described embodiment, to avoid consuming the broadcast resources of the small area cell 34 for broadcasting the system information related to the large area cell, a dedicated signaling method may be used. This is depicted in fig. 14, which schematically illustrates the small area cell 34 transmitting the large area cell system information or modifications related to this information over a dedicated signaling channel 102-104 established with the terminal, and optionally also the small area cell system information and modifications related to other (neighboring) small area cells to the active terminal 35b, transmitting user data over a dedicated channel, which is shown as a solid arrow in fig. 14, similar to the channels 92-94 in fig. 13, the added dashed arrows indicating the transmission of the system information and modifications related thereto over the dedicated signaling channel 102-104. The remaining process description is similar to the embodiment shown in fig. 13. That is, the broadcast channel 101 (shown as a gray triangle in fig. 14) is broadcast by the small-area cell 34 its small-area cell system information to the active terminal 35b, similar to the broadcast channel 91 described above. In the event that there is a modification to the large area cell system information for the large area cell, the large area cell may notify the modification to all small area cells associated with the large area cell coverage area, shown as arrow 105 in fig. 14, similar to notification 95 described above. To support idle terminals 35a, a broadcast channel 106 for the large area cell 32 to transmit at least some large area cell system information, such as a large area cell network, a large area cell identity, various parameters associated with the large area cell broadcast channel, a large area cell neighbor cell list, etc., is similar to the broadcast channel 96 described above.
In the event that the large area cell system information is not needed by the active terminal before the session ends and returns to idle mode again, e.g., the active terminal does not predict a large area cell handover, it is very efficient for the small area cell to send a large area cell system information modification and/or to limit the provision of an indication to move to another large area cell coverage area until the end of the session. Then, for example, when the data connection part is released, it is sufficient that only the small-area cell provides the latest large-area cell system information to the terminal through the corresponding dedicated signaling channel 102 and 104. In this manner, sending potentially large modifications of the large area cell system information and/or indications of modified large area cell coverage may be avoided when the terminal is still active and does not really need such large area cell system information. Since the dedicated signaling channel supports a high code rate, the transmission of the large area cell system information can be accomplished without significant delay compared to sending the information to the terminal 35b immediately for each modification.
The embodiment shown in fig. 14 is intended to be most energy efficient, considering that using dedicated channels is more energy efficient than broadcast channels, and considering that small-area cells have only a small size, it is impossible for more than one terminal receiving broadcast or common channels to benefit from transmitting system information. The additional advantages of using the broadcast/common channel embodiment described above as shown in fig. 13 also apply to this embodiment.
The embodiments of schemes #3 and #4 described above may also be combined. For example, the embodiment of scheme #3 can be used to allocate appropriate small-area cell and large-area cell system information to idle terminals, while the embodiment of scheme #4 can be used to allocate appropriate small-area cell and large-area cell system information to active terminals. That is, the large area cell may be used to send appropriate system information of the small area cell and the large area cell to the terminal in the idle mode, and the small area cell may be used to send appropriate system information of the small area cell and the large area cell to the terminal in the active mode.
Also, as already described above, the embodiments related to scheme #1 may be advantageously used in small area cells and large area cells where small area cell and/or large area cell system information is allocated according to schemes # 2-4.
Embodiments of the invention may be implemented by a program product for use with a computer system. The program(s) of the program product defines functions of the embodiments (including the methods described herein) and can be contained on a variety of, preferably non-transitory, computer-readable storage media. Computer-readable storage media are described including, but not limited to: non-writable storage media (i) in which information can be permanently stored (e.g., read-only memory devices within a computer such as CD-ROM readable disks read by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) and writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory, flash memory) in which information can be modified for storage. The computer program may be run on a processor as described herein.

Claims (17)

1. A method for receiving system information on a terminal (35) in a wireless access telecommunication system (30) comprising at least a small area cell, SA-cell, (33, 34) and a large area cell, LA-cell, (32), the small area cell (33, 34) being optimized to support user data exchange with terminals in active mode, the large area cell (32) being optimized to provide a signaling connection to terminals in idle mode; the terminal comprises an SA-cell interface and an LA-cell interface, and is characterized in that the method comprises the following steps:
when the terminal is in the active mode and the SA-cell radio interface of the terminal is enabled, the terminal:
receiving (61) at least part of SA-cell system information for the terminal from the SA-cell via the SA-cell radio interface,
enabling (62) the terminal's LA-cell radio interface during one or more of a plurality of time periods, an
Receiving (63) at least part of LA-cell system information for the terminal from the LA-cell via the LA-cell radio interface.
2. The method of claim 1, further comprising: when the terminal is in the active mode, the terminal provides an indication to the SA-cell when to suspend transmission of user data from the SA-cell to the terminal.
3. The method of any preceding claim, further comprising: the terminal deactivates the SA-cell radio interface when the LA-cell radio interface is activated, and deactivates the LA-cell radio interface when the SA-cell radio interface is activated.
4. A terminal (35) comprising means for performing the steps of at least one of claims 1-3.
5. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, is configured to carry out the steps of at least one of the claims 1 to 3.
6. A LA-cell (32) configured for use in a method according to one or more of claims 1-3 and/or with a terminal (35) according to claim 4, the LA-cell being configured at least for:
transmitting the at least portion of LA-cell system information for the terminal during at least a portion of the plurality of time periods, wherein each time period of the plurality of time periods is adjacent to a time period during which no portion of LA-cell system information for the terminal is transmitted.
7. The LA-cell of claim 6, wherein the plurality of time periods are set in a first predetermined pattern.
8. The LA-cell of claim 7, wherein the plurality of time periods are set periodically.
9. The LA-cell of any of claims 6-8, wherein at least one of the plurality of time periods is synchronized with the SA-cell sending the SA-cell system information.
10. An SA-cell (33, 34) configured for use in a method according to one or more of claims 1-3, with a terminal (35) according to claim 4 and/or with a LA-cell (32) according to one or more of claims 6-9, the SA-cell being configured at least for:
transmitting at least the portion of SA-cell system information for the terminal during a plurality of SA time periods, wherein each of the plurality of SA time periods is adjacent to a time period during which no portion of SA-cell system information for the terminal is transmitted.
11. The SA-cell of claim 10, further configured to: suspending transmission of user data from the SA-cell to the terminal when at least the portion of SA-cell system information for the terminal is transmitted.
12. The SA-cell according to claim 10 or 11, wherein the plurality of SA time periods are set in a second predetermined pattern.
13. The SA-cell of claim 12, wherein the plurality of SA time periods are set periodically.
14. The SA-cell of claim 10 or 11, wherein at least one of the plurality of SA time periods is synchronized with the LA-cell sending the LA-cell system information.
15. An SA-cell configured for use in the method according to claim 1 or 2, comprising:
receiving, from the terminal, an indication of when to suspend transmission of user data from the SA-cell to the terminal; and
suspending transmission of the user data from the SA-cell to the terminal in response to receiving the indication.
16. The SA-cell of claim 15, wherein at least a portion of at least the portion of SA-cell system information for the terminal is sent by the SA-cell outside of a plurality of LA time periods.
17. The SA-cell of claim 16, wherein the plurality of LA time periods are set in a periodic pattern having a first periodicity and a plurality of SA time periods are set in a periodic pattern having a second periodicity, wherein the second periodicity differs from the first periodicity by a predetermined time, and wherein the predetermined time is at least a duration of one of the plurality of LA time periods.
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