CN106714205B - Method and apparatus for communicating in a heterogeneous network - Google Patents

Method and apparatus for communicating in a heterogeneous network Download PDF

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CN106714205B
CN106714205B CN201510797305.4A CN201510797305A CN106714205B CN 106714205 B CN106714205 B CN 106714205B CN 201510797305 A CN201510797305 A CN 201510797305A CN 106714205 B CN106714205 B CN 106714205B
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virtual cell
transmission point
node
transmission
identifier
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CN106714205A (en
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佘锋
郭海友
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Alcatel Lucent SAS
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    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
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    • H04W24/02—Arrangements for optimising operational condition

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Abstract

Embodiments of the present disclosure provide methods and apparatus for communicating in a heterogeneous network. The heterogeneous network includes a first node, a plurality of transmission points within a coverage area of the first node, each of the plurality of transmission points having a unique physical identifier, and a plurality of devices within the first node. The method at the first node comprises: selecting a group of transmission points from a plurality of transmission points to form a first virtual cell aiming at a first device in the plurality of devices so as to serve the first device; assigning a common first virtual cell identifier to the set of transmission points; and selecting a master transmission point of the first virtual cell from the set of transmission points for scheduling transmissions in the first virtual cell for the first device; wherein the first virtual cell identifier is associated with the first device and is dedicated for transmission to the first device. Embodiments of the present disclosure also provide methods at a transmission point and at a first device, and corresponding apparatuses.

Description

Method and apparatus for communicating in a heterogeneous network
Technical Field
Embodiments of the present disclosure relate to mobile communication systems, and more particularly to heterogeneous networks with dense deployment.
Background
The traffic demand of mobile networks is expected to increase substantially in the following years, both in terms of total traffic demand and in terms of bit rate demand of individual users. To meet this demand, one possible solution is to deploy very dense networks, which may be referred to as Ultra Dense Networks (UDNs).
However, in dense networks, there are two serious problems. One problem is that terminals (e.g., user equipment) may have to face more severe interference, and another problem is that more frequent handovers may occur between small cells.
Therefore, for the scenario of ultra-dense network deployment, it is necessary to design a suitable communication mechanism to reduce interference and/or solve the handover problem.
Disclosure of Invention
The following presents a simplified summary of various embodiments in order to provide a basic understanding of some aspects of various embodiments. This summary is not intended to identify key elements or to delineate the scope of the various embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
A first aspect of the present disclosure provides a method at a first node in a communication system. The communication system also includes a plurality of transmission points deployed within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, and a plurality of devices located within the coverage area of the first node. The method comprises the following steps: selecting a group of transmission points from the plurality of transmission points to form a first virtual cell for a first device of the plurality of devices to serve the first device; assigning a common first virtual cell identifier to the set of transmission points; and selecting a master transmission point of the first virtual cell from the set of transmission points for scheduling transmissions to the first device in the first virtual cell; wherein the common first virtual cell identifier is associated with the first device and is dedicated for transmissions to the first device.
In one embodiment, the method may further comprise: assigning a second virtual cell identifier to a first transmission point of the set of transmission points, the second virtual cell identifier associated with a second device of the plurality of devices and dedicated for transmission to the second device.
In another embodiment, the method may further comprise: sending a measurement configuration to the first device; receiving a measurement report from the first device, the measurement report indicating results of measurements made by the first device according to the measurement configuration; updating the first virtual cell in accordance with the received measurement report, the updating keeping the first virtual cell identifier unchanged; and sending an update message to the transmission points in the first virtual cell and the first device affected by the update.
In a further embodiment, updating the first virtual cell in accordance with the received measurement report may comprise at least one of: selecting a new primary transmission point for the first virtual cell; deleting a transmission point from the first virtual cell; and adding a transmission point to the first virtual cell.
In one embodiment, the update message may include at least one of: physical identifiers of added or deleted transmission points; a reference signal configuration of the added transmission point; a physical identifier of the new primary transmission point; and a virtual cell identifier.
In another embodiment, updating the first virtual cell in accordance with the received measurement report comprises selecting a new primary transmission point for the first virtual cell, and the method may further comprise: determining a difference between an uplink timing from the first device to the new primary transmission point and an uplink timing from the first device to an original primary transmission point; and when the difference is above a predetermined threshold, determining that uplink synchronization is required between the first device and the new primary transmission point, and sending an indication that uplink synchronization is required to be performed to at least one of the new primary transmission point and the first device.
A second aspect of the disclosure provides a method at a first transmission point in a communication system comprising a first node, the first and second transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first and second transmission points each have a unique physical identifier. The method comprises the following steps: receiving, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device; receiving an indication from the first node as a primary transmission point for the first virtual cell; receiving a physical identifier and a reference signal configuration of the second transmission point from the first node; receiving channel state information feedback from the first device; and scheduling a transmission from the second transmission point to the first device.
In one embodiment, the method may further comprise: receiving a second virtual cell identifier from the first node, the second virtual cell identifier associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
In another embodiment, the method may further comprise: receiving an update message for the first virtual cell from the first node.
In yet another embodiment, the update message may include at least one of: physical identifiers of added or deleted transmission points; a reference signal configuration of the added transmission point; the updated physical identification list and the corresponding reference signal configuration thereof; and a physical identifier of the new primary transmission point.
In one embodiment, the update message comprises a physical identifier of the new primary transmission point, and the method may further comprise: forwarding data for the first device to the new primary transmission point.
A third aspect of the disclosure provides a method at a second transmission point in a communication system comprising a first node, a first transmission point and the second transmission point deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first transmission point and the second transmission point each have a unique physical identifier. The method comprises the following steps: receiving, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device; receiving, from the first node, a physical identifier of the first transmission point as a master transmission point of the first virtual cell; receiving, from the first transmission point, a scheduling message for transmission from the second transmission point to the first device; and transmitting data to the first device according to the scheduling message.
In one embodiment, the method may further comprise: receiving a second virtual cell identifier from the first node, the second virtual cell identifier associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
In another embodiment, the method may further comprise: receiving an update message for the first virtual cell from the first node.
In yet another embodiment, the update message may include at least one of: a physical identifier of the deleted transmission point; an updated physical cell identity list; and a physical identifier of the new primary transmission point.
In one embodiment, the method further comprises: receiving an indication from the first node as a new primary transmission point, and updated physical identifiers and reference signal configurations of other transmission points in the first virtual cell, receiving channel state information feedback from the first device; and scheduling transmissions from the updated transmission point in the first virtual cell to the first device. In another embodiment, the method may further comprise: receiving an indication from the first node that the uplink synchronization with the first device is required, and causing the first device to initiate random access. In yet another embodiment, the method may further comprise: receiving forwarded data for the first device from an original primary transmission point.
A fourth aspect of the disclosure provides a method at a first device in a communication system comprising a first node, a plurality of transmission points deployed within a coverage area of the first node, and the first device located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier. The method comprises the following steps: receiving a first virtual cell identifier for a first virtual cell from the first node; the first virtual cell comprises a set of transmission points of the plurality of transmission points, and a first virtual cell identifier is associated with the first device and dedicated to transmissions for the first device; receiving a configuration message for the first virtual cell from the first node, the configuration message comprising physical identifiers of the set of transmission points in the first virtual cell, a reference symbol configuration, and a primary transmission point; receiving scheduling information from the master transmission point; and receiving data transmitted according to the scheduling message from a transmission point in the first virtual cell.
In one embodiment, the method may further comprise: and sending channel state information feedback to the first virtual cell.
In another embodiment, the method further comprises: receiving a measurement configuration from the first node; sending a measurement report to the first node, the measurement report indicating a result of a measurement performed by the first device according to the measurement configuration; and receiving an update message for the first virtual cell from the first node.
In yet another embodiment, the method may further comprise: the method further includes receiving an indication from the first node that uplink synchronization with the primary transmission point is required, and initiating an uplink synchronization procedure with the primary transmission point in response to the indication.
A fifth aspect of the present disclosure provides an apparatus at a first node in a communication system, the communication system further comprising a plurality of transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, the apparatus comprising: a virtual cell establishing unit configured to select, for a first device of the plurality of devices, a group of transmission points from the plurality of transmission points to form a first virtual cell for serving the first device; a virtual cell identifier assignment unit configured to assign a common first virtual cell identifier to the group of transmission points; and a master transmission point selection unit configured to select a master transmission point of the first virtual cell from the set of transmission points for scheduling transmissions to the first device in the first virtual cell; wherein the common first virtual cell identifier is associated with the first device and is dedicated for transmissions to the first device.
A sixth aspect of the present disclosure provides an apparatus at a first transmission point in a communication system, the communication system comprising a first node, the first and second transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first and second transmission points each have a unique physical identifier, the apparatus comprising: a first receiving unit configured to receive, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device; a second receiving unit configured to receive an indication from the first node as a master transmission point of the first virtual cell; a third receiving unit configured to receive a physical identifier and a reference signal configuration of the second transmission point from the first node; a fourth receiving unit configured to receive channel state information feedback from the first device; and a scheduling unit configured to schedule a transmission from the second transmission point to the first device.
A seventh aspect of the present disclosure provides an apparatus at a second transmission point in a communication system, the communication system comprising a first node, a first transmission point and the second transmission point deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first transmission point and the second transmission point each have a unique physical identifier, the apparatus comprising: a first receiving unit configured to receive, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device; a second receiving unit configured to receive, from the first node, a physical identifier of the first transmission point as a master transmission point of the first virtual cell; a third receiving unit configured to receive, from the first transmission point, a scheduling message for transmission from the second transmission point to the first device; and a transmission unit configured to transmit data to the first device according to the scheduling message.
An eighth aspect of the present disclosure provides an apparatus at a first device in a communication system, the communication system comprising a first node, a plurality of transmission points deployed within a coverage area of the first node, and the first device located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, the apparatus comprising: a first receiving unit configured to receive a first virtual cell identifier for a first virtual cell from the first node; the first virtual cell comprises a set of transmission points of the plurality of transmission points, and a first virtual cell identifier is associated with the first device and dedicated to transmissions for the first device; a second receiving unit configured to receive a configuration message of the first virtual cell from the first node, the configuration message comprising physical identifiers of the set of transmission points in the first virtual cell, a reference symbol configuration, and a master transmission point; a third receiving unit configured to receive scheduling information from the master transmission point; and a fourth receiving unit configured to receive data transmitted according to the scheduling message from a transmission point in the first virtual cell.
A ninth aspect of the present disclosure provides an apparatus comprising at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to: the apparatus, in conjunction with the at least one processor, causes the apparatus to perform the method of the first, second, third, or fourth aspect of the disclosure.
According to the method or the device disclosed by the embodiment of the disclosure, the virtual cell can be constructed for serving equipment in a network, a simple and effective signaling flow is provided for identification and management of the virtual cell, interference can be reduced, and/or a handover mechanism can be improved.
Although specific embodiments have been illustrated by way of example in the accompanying drawings, it should be understood, however, that the description herein of specific embodiments is not intended to limit the embodiments to the particular forms disclosed.
Drawings
Objects, advantages and other features of the present disclosure will become more fully apparent from the following disclosure and appended claims. A non-limiting description of the preferred embodiments is given herein, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 illustrates a schematic diagram of an example heterogeneous network;
2a-2b illustrate a flow chart of a method at a first node in a communication system according to an embodiment of the present disclosure;
figure 3 illustrates a signaling diagram for virtual cell identification and management according to one embodiment of the present disclosure;
figure 4 illustrates a signaling diagram for virtual cell management according to one embodiment of the present disclosure;
fig. 5 shows a flow diagram of a method at a transmission point in a communication system, according to an embodiment of the present disclosure;
6a-6b illustrate a flow diagram of another method at a transmission point in a virtual cell in accordance with an embodiment of the present disclosure;
7a-7b illustrate a flow diagram of a method implemented at a device of a communication system in accordance with an embodiment of the present disclosure;
fig. 8 illustrates an exemplary block diagram of an apparatus at a node of a communication network according to an embodiment of the disclosure;
fig. 9 shows an exemplary block diagram of an apparatus at a transmission point of a communication network according to an embodiment of the present disclosure;
fig. 10 shows an exemplary block diagram of a device at another transmission point of a communication network according to an embodiment of the present disclosure; and
fig. 11 shows a block diagram of an apparatus at a device of a communication network, according to an embodiment of the present disclosure.
Detailed Description
In the following description, numerous details are set forth for the purpose of explanation. However, one of ordinary skill in the art will recognize that embodiments of the present disclosure can be practiced without these specific details. Thus, the present disclosure is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.
It will be understood that the terms "first," "second," and the like, are used merely to distinguish one element from another. And in fact, a first element can also be referred to as a second element and vice versa. It will be further understood that the terms "comprises" and "comprising," when used in this specification, specify the presence of stated features, elements, functions, or components, but do not preclude the presence or addition of one or more other features, elements, functions, or components.
For ease of explanation, embodiments of the present disclosure will be described herein in the context of a heterogeneous network having a cellular structure, including a macro base station and small cell base stations under coverage of the macro base station, however, as will be appreciated by those skilled in the art, embodiments of the present disclosure are by no means limited to cellular-structured communication networks, but may be applied in any communication system where similar problems (interference and handover problems due to intensive deployment) exist.
A schematic diagram of a heterogeneous network 100 in which methods and apparatus according to embodiments of the present disclosure may be implemented is shown in fig. 1. Embodiments of the present disclosure need not be implemented in this example network. As shown in fig. 1, the heterogeneous network 100 may include a network node 101, such as a macro base station, which may be, for example, an evolved node b (enb), which may be referred to as MeNB, conforming to the Long Term Evolution (LTE) standard specified by the third generation partnership project (3 GPP). But the network node may also be other devices, such as node bs (NodeB, NB), base transceiver stations, etc., as will be appreciated by those skilled in the art. Within the coverage of a macro base station (e.g., MeNB)101, multiple small cells or wireless access points (110-. There may be multiple terminal devices (e.g., 120-122) within the coverage of the MeNB. Each small cell base station may be referred to as a Transmission Point (TP). The interface between the MeNB and each TP may be through, for example, an X2, although embodiments of the present disclosure are not so limited. Similarly, the TPs may be connected to each other through a specific interface (e.g., an X2 interface). In this example network deployment, the MeNB and TP may also be connected to a Mobility Management Entity (MME), e.g., over an S1-C interface, and/or to a serving gateway (S-GW), e.g., over an S1-U interface. As will be appreciated by those skilled in the art, however, embodiments of the present disclosure are not limited to the specific network architecture shown in fig. 1.
As described above, when dense small cells are deployed within the coverage of the MeNB, the terminal may face severe interference while frequent handovers may need to be performed. For such ultra-dense networks, the concept of virtual cells may be employed. The virtual cell may include a set of small cells or wireless access points selected for interference coordination and/or joint transmission. Currently, there is no specific suitable mechanism for virtual cells. For example, in a very dense network, how to manage the mobility of the terminal device in the virtual cell remains an open issue. If this problem cannot be solved well, a very dense network cannot develop its potential. In the research of a Multiple Input Multiple Output (MIMO) system, concepts such as a measurement set and a cooperation set are proposed with respect to a coordinated multipoint (CoMP), however, these concepts have not yet solved problems in an ultra-dense cell, such as a mobility problem, a cell identification problem, a cell management problem. Therefore, it is necessary to design a specific suitable virtual cell mechanism for the ultra-dense cells.
In view of at least some of the above problems, embodiments of the present disclosure propose improved methods and apparatus for providing virtual cell identification mechanisms and virtual cell management mechanisms during movement of a device (e.g., user equipment, UE).
A flow chart of a method 200 at a first node in a communication system according to an embodiment of the present disclosure is shown in fig. 2a-2 b. The communication system may be, for example, the system 100 described in fig. 1. The first node may be, for example, MeNB 101 in fig. 1. The communication system includes the first node, a plurality of transmission points (e.g., TPs 110-119 in fig. 1) deployed within a coverage area of the first node, and a plurality of devices (e.g., 120-122 in fig. 1) located within the coverage area of the first node. Wherein the plurality of transmission points each have a unique physical identifier, e.g. a physical cell identifier or a small cell ID.
As shown in fig. 2a, the method comprises: at block S201, for a first device of a plurality of devices (e.g., UE120 of fig. 1), selecting a set of transmission points (e.g., TPs 110-116) from the plurality of transmission points to form a first virtual cell for serving the first device; assigning a common first virtual cell identifier to the set of transmission points, the first virtual cell identifier being associated with the first device and being dedicated to transmissions intended for the first device, at block S202; and a block S203 of selecting a Master Transmission Point (MTP) for the first virtual cell from the set of transmission points for scheduling transmissions to the first device in the first virtual cell.
According to the embodiments of the present disclosure, it is possible to conveniently identify a virtual cell, efficiently perform dedicated transmission from the virtual cell to a device, and facilitate scheduling management of the virtual cell.
In one embodiment, a large number of TPs may be grouped into one virtual cell at block S201. In another embodiment, only a small number of TPs may be included within a virtual cell. This may depend on the location of the device, the deployment density of the small cells, or the channel quality between the device and each small cell, etc.
In another embodiment, the MTP selected in block S203 may function as a header of a virtual cell, including, for example, scheduling and transmission of control channels. In one embodiment, the MTP may schedule multiple TPs in the virtual cell to jointly transmit data to the first device.
In another embodiment, the MTP may receive Channel State Information (CSI) feedback from a scheduled first device (e.g., UE120) and perform adaptive scheduling based on the CSI feedback. In yet another embodiment, a non-MTP transmission point in the virtual cell may also receive CSI feedback from the first device.
According to an embodiment of the present disclosure, a TP in a virtual cell may have two Identifiers (IDs). One ID is a physical cell ID (small cell ID), which is different for each cell; and the other ID is a virtual cell ID, which is common to TPs in the virtual cell, in other words, TPs belonging to the same virtual cell may have the same virtual cell ID. In one embodiment, the virtual cell ID may be used for transmissions specific to the first device, e.g., for transmission of demodulation reference signals (DMRS) and scrambling of data transmissions in the virtual cell for the first device. While the physical cell ID may be used for common transmissions within the small cells, e.g., for transmission of common reference signals within each small cell, such as channel state information reference signals (CSI-RS), Common Reference Signals (CRS).
Furthermore, in one embodiment, one TP in the communication system may belong to a plurality of different virtual cells, and thus may have a plurality of virtual cell IDs. Thus, in one embodiment, the method 200 may further include, at block S204, assigning a second virtual cell identifier to a first transmission point of a set of transmission points in the virtual cell, the second virtual cell identifier being associated with a second device (e.g., UE 121) of the plurality of devices and being dedicated for transmission to the second device. That is, one TP included in the first virtual cell may also belong to another virtual cell serving the second device at the same time. With different assigned virtual cell IDs, the TP can easily distinguish transmissions intended for different devices.
In one embodiment, with the mobility of the UE, the virtual cell may be changed and the MTP may also be changed. For example, as shown in fig. 2b, the method 200 may further include, at block S205, the MeNB sending the measurement configuration to the first device; the measurement configuration comprises, for example, parameters for measurement and/or reporting, such as a list of cells to be measured, conditions for triggering measurement reporting, etc. Receiving a measurement report from the first device, the measurement report indicating results of measurements made by the first device according to the measurement configuration, at block S206; updating the first virtual cell according to the received measurement report, which may keep the first virtual cell identifier unchanged, at block S207; and at block S208, an update message is sent to the transmission points and the first device in the first virtual cell that are affected by the update.
This embodiment enables the virtual cell to be changed as the UE moves, thereby guaranteeing the quality of service provided to the UE. It should be noted that the virtual cell is UE-specific. Therefore, the virtual cell ID may not be changed although the virtual cell is changed.
In another example, the updating may also be performed based on other factors than measurement reporting. For example, the quality of each link may be estimated based on an estimate of the distance of the first device from each TP by the MeNB, or based on NACK/ACK statistics in hybrid automatic retransmission, and the like, and may be updated.
In one embodiment, updating the first virtual cell in block S207 may include at least one of: selecting a new master transmission point for a first virtual cell, deleting a transmission point from the first virtual cell, and adding a transmission point to the first virtual cell.
To implement/inform cell update, some configuration signaling may be exchanged. In one embodiment, the update message may include at least one of: the updated physical identification column and its corresponding reference signal configuration, the physical identifier of the added or deleted transmission point, the reference signal configuration of the added transmission point, the physical identifier of the new master transmission point, and the virtual cell identifier. However, as will be appreciated by those skilled in the art, the above messages are presented by way of example only, and indeed in other embodiments the update message may comprise other or additional messages, and embodiments of the present disclosure are not limited to update messages of any particular form and content. For example, the update message may directly broadcast the updated physical identifier columns of all transmission points in the first virtual cell and the corresponding reference signal configurations thereof; it is also possible to indicate only the changed part of the virtual cell configuration, e.g. the physical identifier of the added transmission point and its reference signal configuration, etc.
In another embodiment, different update messages may be sent separately for different TPs. For example, for a TP deleted from a virtual cell, the MeNB may only notify that it is deleted; for a newly added TP, the MeNB may notify the TP of the physical ID of the MTP, the virtual cell ID of the virtual cell, in an update message; for MTP, the MeNB may inform it of the configuration (e.g., reference signal configuration) of the new TP in the updated virtual cell, and so on.
In yet another embodiment, the update message for the first device may be different from the update message for the TP. After the MeNB determines a new virtual cell based on the measurement results and selects a new MTP, the MeNB may send a reference signal (e.g., channel state information reference signal (CSI-RS)) configuration of the TPs in the new virtual cell to the first device. In addition, the physical cell identifier of the TP in the new virtual cell may also be transmitted to the UE. The MeNB may also send signaling to the UE to tell which TP is the new MTP in the virtual cell.
In another embodiment, the content of the update message may also be different for different update results.
In one embodiment, the method 200 may also provide a mechanism for controlling uplink synchronization. For example, in one embodiment, the MTP may change during a virtual cell update. In this case, the first device will communicate with the new MTP in the uplink direction, e.g. for feeding back CSI. The uplink timing may be different because the UE may be at different distances from the new and old MTPs. Thus, in one embodiment, criteria may be introduced to determine whether old uplink timing synchronization can be reused. Considering that a Random Access (RACH) procedure can be used to acquire uplink synchronization, if old synchronization can be reused, it is not necessary to perform a random access procedure for the purpose of uplink synchronization during a virtual cell change, so that time and resources can be saved. Thus, in one embodiment, as shown in fig. 2b, the method 200 may further include, at block S209, determining a difference between an uplink timing from the first device to the new primary transmission point and an uplink timing from the first device to the original primary transmission point; and at block S210, when the difference is above a predetermined threshold, determining that uplink synchronization is required between the first device and the new primary transmission point, and sending an indication that the uplink synchronization is required to at least one of the new primary transmission point and the first device.
In one embodiment, the difference between the uplink timing from the first device to the new primary transmission point and the uplink timing from the first device to the original primary transmission point is determined by the difference between the distance from the first device to the new primary transmission point and the distance from the first device to the original primary transmission point at block S209.
In another embodiment, the indication that uplink synchronization is required sent at block S210 may include a dedicated Random Access Channel (RACH) preamble for the uplink synchronization. In another embodiment, instead of specifying a dedicated RACH preamble, the first device may also be made to randomly select from a set of available preambles.
The embodiment can avoid unnecessary synchronization process when the original uplink synchronization can be reused, save system resources and reduce interference. For example, in current LTE systems, the Timing Advance (TA) for uplink transmissions has a minimum granularity of 0.52us, i.e., differences of less than 0.52us will not be distinguishable. This difference corresponds approximately to 78 meters in distance. Thus, in a very dense network, if the difference between the UE's distance from the new MTP and the distance between the UE and the original MTP is shorter than this distance, the uplink synchronization is likely to be able to be reused. In one embodiment, in this case, the uplink synchronization procedure may not be performed between the first device and the new MTP.
A signaling diagram for virtual cell identification and management according to one embodiment of the present disclosure is shown in fig. 3. In fig. 3, it is assumed that the UE is able to access the MeNB and establishes a Radio Resource Control (RRC) connection with the MeNB. As shown in fig. 3, the identification process of the virtual cell may include the following steps:
step 1: the MeNB sends the measurement configuration to the UE. The measurement configuration may be sent, for example, by RRC signaling. In the RRC signaling, a measurement list may be included, in which a large number of small cells may be included.
Step 2: according to the configured reporting trigger condition in the received measurement configuration, the UE will report a plurality of measurement results to the MeNB. Each measurement result will include a physical cell ID of the measured cell and an indication of received signal strength (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), etc.). Then, based on the reported measurements, the MeNB can know, for example, the approximate location of the UE, and/or the large-scale link quality of the UE with each TP.
And step 3: upon receiving the UE's report, the MeNB may determine the virtual cell and the MTP. Embodiments of the present disclosure are not limited to virtual cell and MTP selection with any particular algorithm. In practice, the selection may be made according to specific rules, as desired.
And 4, step 4: the MeNB allocates and transmits (notifies) a virtual cell ID to the TPs in the virtual cell. It should be noted that one TP may belong to multiple virtual cells, in which case the TP may be assigned more than one virtual cell ID. The virtual cell ID may be used for scrambling of demodulation reference signals (DMRSs) and data for the UE.
And 5: the MeNB sends configuration parameters of TPs in the virtual cell to the UE. The configuration of the TPs may be used for Channel State Information (CSI) feedback. For example, the CSI-RS configuration of the TPs in the virtual cell and their physical cell IDs. Meanwhile, the MeNB also notifies the UE of the virtual cell ID of the virtual cell.
Step 6: the UE feeds back CSI to the virtual cell (e.g., MTP of the virtual cell).
And 7: based on the CSI feedback, the MTP may perform adaptive scheduling and send scheduling information to other TPs over, for example, but not limited to, the X2 interface. Then, joint data transmission may be performed.
It should be noted that the problem of delay of the X2 interface cannot be neglected, however in practice, fiber, microwave, millimeter wave (mmW) radio can all be considered as a low delay X2 interface. Embodiments of the present disclosure are not limited to the specific low latency techniques listed herein.
A signaling diagram for virtual cell management according to one embodiment of the disclosure is shown in fig. 4. As shown in fig. 4, with UE mobility in a super-dense network, the management procedure may be implemented as follows:
step 1: as the UE moves, the MeNB will adaptively modify the measurement configuration, and the MeNB will send the modified measurement configuration to the UE. Accordingly, based on the configured reporting trigger condition, the UE may report an updated measurement result, e.g. report RSRP, to the MeNB.
Step 2: based on the measurement results, the MeNB will decide whether to select a new virtual cell or a new MTP. If a new MeNB or virtual cell needs to be selected, proceed to step 3.
And step 3: the MeNB sends a handover command to the current MTP in the virtual cell over e.g. the X2 interface informing that a handover to the new MTP is to be made.
And 4, step 4: the MeNB sends handover commands and receives feedback from the new MTP (target TP) of the virtual cell over, for example, the X2 interface. The command to MTP may include the virtual cell ID and CSI-RS configurations of other TPs in the updated virtual cell, as well as physical cell IDs of other TPs.
And 5: after the MeNB selects the MTP and the new virtual cell, the MeNB may send signaling to the UE informing information about the new virtual cell, e.g., information about the new MTP. The physical cell ID and corresponding CSI-RS configuration for each TP in the new virtual cell may also be included in the signaling. The MeNB may also tell the UE which TP is MTP in this signaling. Further, optionally, a dedicated Random Access Channel (RACH) preamble for performing random access with the new MTP may also be included in the signaling.
Step 6: the old MTP may forward the data to the new MTP over the X2 interface.
And 7: in a very dense network, it is possible that uplink synchronization may be reused due to the small spatial distance between the new MTP and the old MTP. For example, in LTE, the minimum TA granularity is 0.52us, which corresponds approximately to a distance of 78 meters. Therefore, in a very dense network, if the difference in distance between the UE and the two MTPs is less than 78 meters, the uplink synchronization is likely to be reused. In this way, the handover procedure can be simplified. On the other hand, if uplink synchronization cannot be reused, the UE needs to send RACH preamble to a new MTP for uplink synchronization.
And 8: the new MTP may respond with an uplink resource allocation and/or Timing Advance (TA) message for the RACH preamble sent by the UE.
And step 9: and transmitting data between the new virtual cell and the UE.
The method at the MeNB in the communication system and the system signaling flow are described above in connection with fig. 2a, 2b, 3 and 4. A method 500 at a TP in a communication system according to an embodiment of the present disclosure will be described below in conjunction with fig. 5. Fig. 5 shows a flow diagram of a method 500. The method 500 may be performed by a first transmission point (e.g., the TP110 shown in fig. 1) in the communication system 100. As shown in fig. 1, the communication system 100 includes a first node (e.g., MeNB), the first transmission point (e.g., TP 110) and a second transmission point (e.g., TP 111) deployed within a coverage area of the first node, wherein the first transmission point and the second transmission point each have a unique physical identifier (e.g., physical cell ID), and a plurality of devices (e.g., UEs 120-122) located within the coverage area of the first node. As shown in fig. 5, the method includes: at block S501, the TP110 receives, from a first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device (e.g., UE120) of a plurality of devices and includes a first transmission point and a second transmission point, the first virtual cell identifier being dedicated for transmission to the first device; receiving an indication of a primary transmission point (MTP) from a first node as a first virtual cell, at block S502; at block S503, receiving a physical identifier and a reference signal configuration of a second transmission point (e.g., TP 111) from a first node; receiving channel state information feedback from the first device at block S504; and scheduling a transmission from the second transmission point to the first device at block S505.
According to the above embodiments, the TP110 in the communication system can be specified by the MeNB as an MTP in the virtual cell, which can learn information of other TPs (e.g. second transmission points, TP 111) in the virtual cell from the MeNB and schedule transmissions from the other TPs in the virtual cell to the device according to the information from the device. It should be noted that with the method 500, the MTP can be enabled to jointly schedule joint transmission of multiple TPs in the virtual cell to the first device.
In one embodiment, the TP110 that is selected as the MTP of a virtual cell may also be in multiple virtual cells at the same time. In this case, the method 500 may further include, at block S506, the TP110 receiving a second virtual cell identifier from the first node, the second virtual cell identifier being associated with a second device (e.g., UE 121) of the plurality of devices and being dedicated for transmission to the second device.
As described above in connection with fig. 2 and 4, the MeNB may update the virtual cell as the device moves. Thus, in one embodiment, the TP110 may receive an update message for a first virtual cell from a first node (e.g., MeNB) at block S507. The update message may include different contents depending on the result of the update. In one embodiment, the update message may include at least one of: the updated physical identification column of each transmission point in the first virtual cell and the corresponding reference signal configuration thereof, and the physical identifier of the added or deleted transmission point; a reference signal configuration of the added transmission point; and a physical identifier of the new primary transmission point.
If the TP110 is kept as an MTP in the update, it may update the schedule according to the updated TP list in the virtual cell and its corresponding configuration. If the TP110 is no longer an MTP after the update, it may be informed of the physical cell identity of the new MTP and, if necessary, forward data for the first device to the new MTP at block S508. An example of this has been shown in fig. 4.
Fig. 6a-6b illustrate a flow diagram of another method 600 at a TP in a virtual cell in accordance with an embodiment of the present disclosure. The method 600 may also be implemented in, for example, the communication system 100 shown in fig. 1. The method 600 may be performed by a second transmission point (e.g., TP 111 in fig. 1). As shown in fig. 6a, the method comprises: at block S601, receiving, from a first node (e.g., MeNB in fig. 1), a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of a plurality of devices and includes a first transmission point and a second transmission point, as previously described, the first virtual cell identifier being dedicated for transmission to the first device; receiving, from a first node, a physical identifier of a first transmission point being a master transmission point of a first virtual cell, at block S602; receiving a scheduling message from the first transmission point for transmission from the second transmission point to the first device at block S603; and transmitting data to the first device according to the scheduling message at block S604.
The method 600 enables a TP in a communication system to be included in a virtual cell and to operate as a non-MTP. The TP is capable of receiving scheduling information from the MTP so that data transmission to the first device can be performed accordingly. As can be appreciated by one skilled in the art, in a virtual cell, multiple TPs may perform the method 600 such that the multiple TPs can perform joint transmission for a first device.
As previously described, in one embodiment, a TP in a communication system may be included in multiple virtual cells. Accordingly, the method 600 may further include, at block S605, receiving a second virtual cell identifier from the first node, the second virtual cell identifier being associated with a second device of the plurality of devices and being dedicated for transmission to the second device.
In addition, as described above in connection with fig. 2a, 2b, 4, and 5, the MeNB may update the virtual cell as the device moves and send an update message to the relevant TP. Thus, in one embodiment, the method 600 may further include, at block S606, receiving an update message for the first virtual cell from the first node, as shown in fig. 6 b. The content of the update message may vary depending on the update result. In one embodiment, the update message may include at least one of: a physical identifier of the deleted transmission point; and a physical identifier of the new primary transmission point.
In one embodiment, the TP 111 may be selected by the MeNB as a new MTP in the virtual cell update. In this case, as shown in fig. 6b, the method 600 may further include, at block S607, receiving from the first node an indication to be a new master transmission point, and updated physical identifiers and reference signal configurations of other transmission points in the first virtual cell; at block S608, receiving channel state information feedback from the first device; and scheduling transmission from the updated transmission point in the first virtual cell to the first device, at block S609.
As previously mentioned, the uplink between the device to the new MTP may reuse the timing synchronization of the uplink between the device to the old MTP in certain cases, for example when the difference between the timing between the device to the new MTP and the timing between the device to the old MTP is less than a predetermined threshold or when the difference between the distance between the device to the new MTP and the distance between the device to the old MTP is less than a predetermined threshold. In other cases, the uplink synchronization between the device and the new MTP cannot reuse the uplink synchronization between the device and the old MTP. Thus, in some embodiments, the method 600 may further include, at block S610, receiving an indication from the first node that uplink synchronization with the first device is required, and at block S611, causing the first device to initiate random access. In one embodiment, the TP 111 may notify the first device to initiate random access for uplink synchronization through downlink signaling (e.g., paging message).
In another embodiment, the TP 111 may receive forwarded data for the first device from the original primary transmission point as a new MTP in block S612, as shown in fig. 4. In one embodiment, this forwarding may be done over an X2 interface between the new MTP and the old MTP, however, as can be appreciated by those skilled in the art, embodiments of the present disclosure are not limited to using this interface.
Fig. 7a-7b illustrate a flow diagram of a method 700 implemented at a device of a communication system in accordance with an embodiment of the present disclosure. The method 700 may be implemented in, for example, the communication system 100 shown in fig. 1. The method 700 may be performed by a first device (e.g., UE120 in fig. 1). As shown in fig. 7a, the method comprises: at block S701, receiving a first virtual cell identifier for a first virtual cell from a first node (e.g., MeNB); the first virtual cell comprises a set of transmission points of the plurality of transmission points and a first virtual cell identifier is associated with the first device and dedicated to transmissions for the first device; at block S702, receiving a configuration message of a first virtual cell from a first node, the configuration message comprising physical identifiers of a set of transmission points in the first virtual cell, a reference symbol configuration, and a primary transmission point; at block S703, receiving scheduling information from a master transmission point; and receiving data transmitted according to the scheduling message from a transmission point in the first virtual cell, at block S704.
The method 700 enables a device in a communication system to be served by a set of small cells having a common virtual cell ID such that the device does not need to perform handover operations while moving within the virtual cell. In addition, the quality of service of the device can be improved by joint transmission within the virtual cell.
In one embodiment, as shown in fig. 7b, in order for the primary MTP to efficiently perform scheduling, the device may send channel state information feedback to the primary transmission point at block S705. In another embodiment, the device may also send channel state information feedback to other transmission points in the virtual cell at block S705.
In another embodiment, the device may receive a measurement configuration from the first node in block S706; at block S707, sending a measurement report to the first node, the measurement report indicating a result of measurements performed by the first device according to the measurement configuration; and at block S708, an update message for the first virtual cell is received from the first node. This enables the MeNB to continuously update the configuration of the virtual cells as the device moves.
The device may also send a random access request to the master transmission point as needed for uplink synchronization. In one embodiment, the uplink synchronization procedure is initiated only when the device receives an indication from the first node that uplink synchronization with the primary transmission point is required, e.g. by initiating random access. Accordingly, the method 700 may further include, at block S709, receiving an indication from the first node that uplink synchronization with the primary transmission point is required, and, at block S710, initiating an uplink synchronization procedure with the primary transmission point in response to the indication. In one embodiment, the indication from the first node that uplink synchronization with the primary transmission point is required may be, for example, a dedicated random access preamble. In another embodiment, the device may not receive the dedicated random access preamble, but may randomly choose the preamble to use from the available preamble set when the RACH needs to be initiated. In one embodiment, the device may not perform RACH to uplink synchronization when the uplink between the device and the new MTP can reuse the uplink synchronization between the device and the old MTP. This enables saving signalling and random access resources and reducing interference in certain situations.
The structure of a device according to an embodiment of the present disclosure is described below with reference to fig. 8-11.
Fig. 8 illustrates an exemplary block diagram of an apparatus 800 according to an embodiment of the disclosure. In one embodiment, the apparatus 800 may be implemented as a first node in a communication system, such as the MeNB 101 in the communication system 100 shown in fig. 1, or a portion thereof. The apparatus 800 is operable to perform the method 200 described with reference to fig. 2a-2b, as well as any other processes and methods. It should be understood that the method 200 is not limited to being performed by the apparatus 800, and that at least some of the blocks of the method 200 may be performed by other apparatuses or entities.
As shown in fig. 8, the apparatus 200 includes a virtual cell establishing unit 801 configured to select, for a first device of the plurality of devices, a group of transmission points from the plurality of transmission points to form a first virtual cell for serving the first device; a virtual cell identifier assignment unit 802 configured to assign a common first virtual cell identifier to the set of transmission points; and a master transmission point selecting unit 803 configured to select a master transmission point of the first virtual cell from the set of transmission points for scheduling transmissions for the first device in the first virtual cell; wherein the common first virtual cell identifier is associated with the first device and is dedicated for transmissions to the first device.
In one embodiment, the virtual cell establishment unit 801, the virtual cell identifier assignment unit 802 and the master transmission point selection unit 803 may perform the operations of blocks S201-S203, respectively, of the method 200 described in connection with fig. 2. Therefore, the description made with reference to fig. 2 is equally applicable here and therefore will not be repeated.
In one embodiment, the virtual cell identifier assignment unit 802 may be further configured to assign a second virtual cell identifier to a first transmission point of the set of transmission points, the second virtual cell identifier being associated with a second device of the plurality of devices and dedicated for transmission to the second device.
In another embodiment, the apparatus 800 may further include: a measurement configuration unit 804 configured to send a measurement configuration to the first device; a measurement result receiving unit 805 configured to receive a measurement report from the first device, the measurement report indicating a result of measurement performed by the first device according to the measurement configuration; a virtual cell updating unit 806 configured to update the first virtual cell according to the received measurement report, the update keeping the first virtual cell identifier unchanged; and an update message sending unit 807 configured to send an update message to the transmission points in the first virtual cell and the first device affected by the update. In an embodiment the virtual cell updating unit 806 is configured to update the first virtual cell by at least one of: selecting a new primary transmission point for the first virtual cell; deleting a transmission point from the first virtual cell; and adding a transmission point to the first virtual cell.
In one embodiment, the update message may include at least one of: the updated physical identification column of each transmission point in the first virtual cell and the corresponding reference signal configuration thereof, and the physical identifier of the added or deleted transmission point; a reference signal configuration of the added transmission point; a physical identifier of the new primary transmission point; and a virtual cell identifier.
In another embodiment, the virtual cell updating unit 806 is configured to select a new master transmission point for the first virtual cell, and the apparatus 800 may further comprise: an uplink timing determination unit 808 configured to determine a difference between an uplink timing from the first device to the new master transmission point and an uplink timing from the first device to an original master transmission point; and an uplink synchronization control unit 809 configured to determine that uplink synchronization is required between the first device and the new master transmission point when the difference is above a predetermined threshold, and to send an indication that the uplink synchronization is required to be performed to at least one of the new master transmission point and the first device. In one embodiment, sending the indication that the uplink synchronization is required comprises: transmitting a dedicated random access preamble for the uplink synchronization.
Fig. 9 illustrates an exemplary block diagram of an apparatus 900 according to an embodiment of the disclosure. In one embodiment, the apparatus 900 may be implemented as, or a part of, a first transmission point in a communication system, such as the TP110 in the communication system 100 shown in fig. 1. The apparatus 900 is operable to perform the method 500 described with reference to fig. 5, as well as any other processes and methods. It should be understood that the method 500 is not limited to being performed by the apparatus 900 and that at least some of the blocks of the method 500 may be performed by other apparatuses or entities.
As shown in fig. 9, the apparatus 900 comprises the first receiving unit 901 configured to receive, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and comprises the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission for the first device; a second receiving unit 902 configured to receive an indication from the first node as a master transmission point of the first virtual cell; a third receiving unit 903 configured to receive the physical identifier and the reference signal configuration of the second transmission point from the first node; a fourth receiving unit 904 configured to receive channel state information feedback from the first device; and a scheduling unit 905 configured to schedule a transmission from the second transmission point to the first device.
In one embodiment, the units 901 and 905 may be configured to perform the operations of the blocks 501 and 505 of the method 500 described with reference to fig. 5, respectively, and thus the description with reference to fig. 5 is also applicable here and is not repeated herein.
In one embodiment, the apparatus 900 may further comprise a fifth receiving unit 906 configured to receive a second virtual cell identifier from the first node, the second virtual cell identifier being associated with a second device of the plurality of devices and being dedicated for transmission to the second device.
In another embodiment, the apparatus 900 may further include a sixth receiving unit 907 configured to receive an update message of the first virtual cell from the first node. In one embodiment, the update message comprises at least one of: the updated physical identification column of each transmission point in the first virtual cell and the corresponding reference signal configuration thereof, and the physical identifier of the added or deleted transmission point; a reference signal configuration of the added transmission point; and a physical identifier of the new primary transmission point.
In one embodiment, the update message received by the sixth receiving unit 907 includes a physical identifier of a new primary transmission point, and the apparatus 900 may further include: a forwarding unit 908 configured to forward data for the first device to the new master transmission point.
Fig. 10 shows a block diagram of an apparatus 1000 implemented at another transmission node in a communication system. In one embodiment, the apparatus 1000 may be implemented as, or a part of, a second transmission point in a communication system, such as the TP 111 in the communication system 100 shown in fig. 1. The apparatus 1000 is operable to perform the method 600 described with reference to fig. 6a-6b, as well as any other processes and methods. It should be understood that the method 600 is not limited to being performed by the apparatus 1000, and that at least some of the blocks of the method 600 may be performed by other apparatuses or entities.
As shown in fig. 10, the apparatus 1000 comprises a first receiving unit 1001 configured to receive, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and comprises the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission for the first device; a second receiving unit 1002 configured to receive a physical identifier of the first transmission point as a master transmission point of the first virtual cell from the first node; a third receiving unit 1003 configured to receive, from the first transmission point, a scheduling message for transmission from the second transmission point to the first device; and a transmitting unit 1004 configured to transmit data to the first device according to the scheduling message.
In one embodiment, the units 1001 and 1004 may be configured to perform the operations of the blocks 601 and 604 of the method 600 described with reference to fig. 6, respectively, and thus the description with reference to fig. 6a is equally applicable here and is not repeated herein.
In one embodiment, the apparatus 1000 may further include: a fourth receiving unit 1005 configured to receive a second virtual cell identifier from the first node, the second virtual cell identifier being associated with a second device of the plurality of devices and being dedicated for transmission to the second device.
In another embodiment, the apparatus 1000 may further include: a fifth receiving unit 1006, configured to receive an update message of the first virtual cell from the first node. In one embodiment, the update message comprises at least one of: the updated physical identification column of each transmission point in the first virtual cell, the corresponding reference signal configuration and the deleted physical identifier of the transmission point; and a physical identifier of the new primary transmission point.
In yet another embodiment, the apparatus 1000 may further include: a sixth receiving unit 1007 configured to receive an indication as a new master transmission point from the first node, and the updated physical identifiers and reference signal configurations of other transmission points in the first virtual cell; a seventh receiving unit 1008 configured to receive channel state information feedback from the first device; and a scheduling unit 1009 configured to schedule transmission from the updated transmission point in the first virtual cell to the first device.
In one embodiment, the apparatus may further include an eighth receiving unit 1010 configured to receive, from the first node, an indication that the uplink synchronization with the first device is required, and a random access control unit 1011 configured to cause the first device to initiate random access.
In another embodiment, the apparatus may further comprise a ninth receiving unit 1012 configured to receive forwarded data for said first device from the original primary transmission point.
Fig. 11 shows a block diagram of an apparatus 1100 implemented at a device in a communication system. In one embodiment, the apparatus 1100 may be implemented as, or a part of, a device (120-122) in, for example, the communication system 100 shown in fig. 1. The apparatus 1100 is operable to perform the method 700 described with reference to fig. 7a-7b, as well as any other processes and methods. It should be understood that the method 700 is not limited to being performed by the apparatus 1100, and that at least some of the blocks of the method 700 may be performed by other apparatuses or entities.
As shown in fig. 11, the apparatus 1100 comprises a first receiving unit 1101 configured to receive a first virtual cell identifier for a first virtual cell from the first node; the first virtual cell comprises a set of transmission points of the plurality of transmission points, and a first virtual cell identifier is associated with the first device and dedicated to transmissions for the first device; a second receiving unit 1102 configured to receive a configuration message of the first virtual cell from the first node, the configuration message comprising physical identifiers of the set of transmission points in the first virtual cell, a reference symbol configuration, and a primary transmission point; a third receiving unit 1103 configured to receive scheduling information from the master transmission point; and a fourth receiving unit 1104 configured to receive data transmitted according to the scheduling message from the transmission point in the first virtual cell.
In one embodiment, the apparatus 1100 may further comprise: a first sending unit 1105 configured to send channel state information feedback to the virtual cell (e.g., without limitation, a master transmission point).
In another embodiment, the apparatus 1100 may further comprise: a fifth receiving unit 1106 configured to receive a measurement configuration from the first node; a measurement report transmitting unit 1107 configured to transmit a measurement report to the first node, the measurement report indicating a result of measurement performed by the first device according to the measurement configuration; and a sixth receiving unit 1108 configured to receive an update message of the first virtual cell from the first node.
In yet another embodiment, the apparatus 1100 may further comprise: a seventh receiving unit 1109 configured to receive an indication from the first node that uplink synchronization with a primary transmission point needs to be performed (for example, the indication may be a dedicated random access preamble); and a random access unit 1110 configured to initiate an uplink synchronization procedure with the high primary transmission point in response to receiving the indication.
As can be appreciated by those skilled in the art, the apparatus 800-1100 may also include other units not shown in FIGS. 8-11, respectively, and in some embodiments, some of the units in FIGS. 8-11 may be omitted.
Advantages of the method and apparatus proposed by embodiments of the present disclosure include at least one of:
-enabling efficient identification and management of virtual cells;
-reducing interference;
-saving resources;
-improving the handover mechanism.
Those skilled in the art will readily recognize that blocks or steps of the various methods described above may be performed by a programmed computer. In the present disclosure, some embodiments are also intended to encompass program storage devices, e.g., digital data storage media, that are machine or computer readable and encode machine-executable or computer-executable programs of instructions, wherein the instructions perform some or all of the steps of the above-described methods. The program storage device may be, for example, a digital memory, a magnetic storage medium such as a magnetic disk and magnetic tape, a hard disk drive, or an optically readable digital data storage medium. This embodiment is also intended to cover a computer programmed to perform the steps of the above-described method. Some embodiments are also intended to encompass an apparatus comprising at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to: the apparatus, in conjunction with the at least one processor, is caused to perform a method 200, 500, 600, or 700.
The functions of the various elements of the apparatus shown in the figures may be provided through the use of software, dedicated hardware as well as hardware capable of executing software in association with appropriate software, or firmware, or a combination thereof. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors. Furthermore, the term "processor" may include, but is not limited to, Digital Signal Processor (DSP) hardware, network processors, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), Read Only Memories (ROMs) for storing software, Random Access Memories (RAMs) and non-volatile storage. Other hardware, conventional and/or custom, may also be included.
It should be understood by those skilled in the art that the description and drawings merely illustrate the principles of embodiments of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the embodiments of the disclosure and are included within its spirit and scope. Moreover, all examples set forth herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the embodiments of the disclosure and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims (40)

1. A method at a first node in a communication system, the communication system further comprising a plurality of transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, the method comprising:
for a first device of the plurality of devices, selecting a group of transmission points from the plurality of transmission points to form a first virtual cell for serving the first device;
assigning a common first virtual cell identifier to the set of transmission points; and
selecting a master transmission point of the first virtual cell from the set of transmission points for scheduling transmissions to the first device in the first virtual cell;
wherein the common first virtual cell identifier is associated with the first device and is dedicated for transmissions to the first device.
2. The method of claim 1, further comprising:
assigning a second virtual cell identifier to a first transmission point of the set of transmission points, the second virtual cell identifier associated with a second device of the plurality of devices and dedicated for transmission to the second device.
3. The method of claim 1 or 2, further comprising:
sending a measurement configuration to the first device;
receiving a measurement report from the first device, the measurement report indicating results of measurements made by the first device according to the measurement configuration;
updating the first virtual cell in accordance with the received measurement report, the updating keeping the first virtual cell identifier unchanged; and
sending an update message to transmission points in the first virtual cell and the first device that are affected by the update.
4. The method of claim 3, wherein updating the first virtual cell in accordance with the received measurement report comprises at least one of:
selecting a new primary transmission point for the first virtual cell;
deleting a transmission point from the first virtual cell; and
adding a transmission point to the first virtual cell.
5. The method of claim 3, wherein the update message comprises at least one of:
physical identifiers of added or deleted transmission points;
a reference signal configuration of the added transmission point;
a physical identifier of the new primary transmission point; and
a virtual cell identifier.
6. The method of claim 3, wherein updating the first virtual cell in accordance with the received measurement report comprises selecting a new master transmission point for the first virtual cell, and further comprising:
determining a difference between an uplink timing from the first device to the new primary transmission point and an uplink timing from the first device to an original primary transmission point; and
when the difference is above a predetermined threshold, determining that uplink synchronization is required between the first device and the new primary transmission point, and sending an indication to at least one of the new primary transmission point and the first device that the uplink synchronization is required.
7. A method at a first transmission point in a communication system, the communication system comprising a first node, the first and second transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first and second transmission points each have a unique physical identifier, the method comprising:
receiving, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device;
receiving an indication from the first node as a primary transmission point for the first virtual cell;
receiving a physical identifier and a reference signal configuration of the second transmission point from the first node;
receiving channel state information feedback from the first device; and
scheduling a transmission from the second transmission point to the first device.
8. The method of claim 7, further comprising:
receiving a second virtual cell identifier from the first node, the second virtual cell identifier associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
9. The method of claim 7 or 8, further comprising:
receiving an update message for the first virtual cell from the first node.
10. The method of claim 9, wherein the update message comprises at least one of:
physical identifiers of added or deleted transmission points;
a reference signal configuration of the added transmission point;
the updated physical identification list and the corresponding reference signal configuration thereof; and
physical identifier of the new primary transmission point.
11. A method at a second transmission point in a communication system, the communication system comprising a first node, a first transmission point and the second transmission point deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first transmission point and the second transmission point each have a unique physical identifier, the method comprising:
receiving, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device;
receiving, from the first node, a physical identifier of the first transmission point as a master transmission point of the first virtual cell;
receiving, from the first transmission point, a scheduling message for transmission from the second transmission point to the first device; and
and transmitting data to the first equipment according to the scheduling message.
12. The method of claim 11, further comprising:
receiving a second virtual cell identifier from the first node, the second virtual cell identifier associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
13. The method of claim 11 or 12, further comprising:
receiving an update message for the first virtual cell from the first node.
14. The method of claim 13, wherein the update message comprises at least one of:
a physical identifier of the deleted transmission point;
an updated physical cell identity list; and
physical identifier of the new primary transmission point.
15. The method of claim 11, further comprising:
receiving from the first node an indication as a new master transmission point and updated physical identifiers and reference signal configurations of other transmission points in the first virtual cell, an
Receiving channel state information feedback from the first device; and
scheduling transmissions from the updated transmission point in the first virtual cell to the first device.
16. The method of claim 15, further comprising:
receiving an indication from the first node that uplink synchronization with the first device is required, an
Causing the first device to initiate random access.
17. The method of claim 15, further comprising:
receiving forwarded data for the first device from an original primary transmission point.
18. A method at a first device in a communication system, the communication system comprising a first node, a plurality of transmission points deployed within a coverage area of the first node, and the first device located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, the method comprising:
receiving a first virtual cell identifier for a first virtual cell from the first node; the first virtual cell comprises a set of transmission points of the plurality of transmission points, and a first virtual cell identifier is associated with the first device and dedicated to transmissions for the first device;
receiving a configuration message for the first virtual cell from the first node, the configuration message comprising physical identifiers of the set of transmission points in the first virtual cell, a reference symbol configuration, and a primary transmission point;
receiving scheduling information from the master transmission point; and
receiving data transmitted according to the scheduling message from a transmission point in the first virtual cell.
19. The method of claim 18, further comprising:
receiving a measurement configuration from the first node;
sending a measurement report to the first node, the measurement report indicating a result of a measurement performed by the first device according to the measurement configuration; and
receiving an update message for the first virtual cell from the first node.
20. The method of claim 18, further comprising:
receiving an indication from the first node that uplink synchronization with the primary transmission point is required, an
Initiating an uplink synchronization procedure with the primary transmission point in response to the indication.
21. An apparatus at a first node in a communication system, the communication system further comprising a plurality of transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, the apparatus comprising:
a virtual cell establishing unit configured to select, for a first device of the plurality of devices, a group of transmission points from the plurality of transmission points to form a first virtual cell for serving the first device;
a virtual cell identifier assignment unit configured to assign a common first virtual cell identifier to the group of transmission points; and
a master transmission point selection unit configured to select a master transmission point of the first virtual cell from the set of transmission points for scheduling transmissions for the first device in the first virtual cell;
wherein the common first virtual cell identifier is associated with the first device and is dedicated for transmissions to the first device.
22. The apparatus according to claim 21, wherein the virtual cell identifier assignment unit is further configured to assign a second virtual cell identifier to a first transmission point of the set of transmission points, the second virtual cell identifier being associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
23. The apparatus of claim 21 or 22, further comprising:
a measurement configuration unit configured to transmit a measurement configuration to the first device;
a measurement result receiving unit configured to receive a measurement report from the first device, the measurement report indicating a result of measurement performed by the first device according to the measurement configuration;
a virtual cell update unit configured to update the first virtual cell according to the received measurement report, the update keeping the first virtual cell identifier unchanged; and
an update message sending unit configured to send an update message to the transmission points in the first virtual cell and the first device affected by the update.
24. The apparatus according to claim 23, wherein the virtual cell updating unit is configured to update the first virtual cell by at least one of:
selecting a new primary transmission point for the first virtual cell;
deleting a transmission point from the first virtual cell; and
adding a transmission point to the first virtual cell.
25. The apparatus of claim 23, wherein the update message comprises at least one of:
physical identifiers of added or deleted transmission points;
a reference signal configuration of the added transmission point;
a physical identifier of the new primary transmission point; and
a virtual cell identifier.
26. The apparatus of claim 23, wherein the virtual cell update unit is configured to select a new master transmission point for the first virtual cell, and the apparatus further comprises:
an uplink timing determination unit configured to determine a difference between an uplink timing from the first device to the new master transmission point and an uplink timing from the first device to an original master transmission point; and
an uplink synchronization control unit configured to determine that uplink synchronization is required between the first device and the new master transmission point when the difference is above a predetermined threshold, and to send an indication that the uplink synchronization is required to at least one of the new master transmission point and the first device.
27. An apparatus at a first transmission point in a communication system, the communication system comprising a first node, the first and second transmission points deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first and second transmission points each have a unique physical identifier, the apparatus comprising:
a first receiving unit configured to receive, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device;
a second receiving unit configured to receive an indication from the first node as a master transmission point of the first virtual cell;
a third receiving unit configured to receive a physical identifier and a reference signal configuration of the second transmission point from the first node;
a fourth receiving unit configured to receive channel state information feedback from the first device; and
a scheduling unit configured to schedule a transmission from the second transmission point to the first device.
28. The apparatus of claim 27, further comprising:
a fifth receiving unit configured to receive, from the first node, a second virtual cell identifier associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
29. The apparatus of claim 27 or 28, further comprising:
a sixth receiving unit configured to receive an update message of the first virtual cell from the first node.
30. The apparatus of claim 29, wherein the update message comprises at least one of:
physical identifiers of added or deleted transmission points;
a reference signal configuration of the added transmission point;
the updated physical identification list and the corresponding reference signal configuration thereof; and
physical identifier of the new primary transmission point.
31. An apparatus at a second transmission point in a communication system, the communication system including a first node, a first transmission point and the second transmission point deployed within a coverage area of the first node, and a plurality of devices located within the coverage area of the first node, wherein the first transmission point and the second transmission point each have a unique physical identifier, the apparatus comprising:
a first receiving unit configured to receive, from the first node, a first virtual cell identifier for a first virtual cell, wherein the first virtual cell is specific to a first device of the plurality of devices and includes the first transmission point and the second transmission point, the first virtual cell identifier being dedicated for transmission to the first device;
a second receiving unit configured to receive, from the first node, a physical identifier of the first transmission point as a master transmission point of the first virtual cell;
a third receiving unit configured to receive, from the first transmission point, a scheduling message for transmission from the second transmission point to the first device; and
a transmission unit configured to transmit data to the first device according to the scheduling message.
32. The apparatus of claim 31, further comprising:
a fourth receiving unit configured to receive, from the first node, a second virtual cell identifier associated with a second device of the plurality of devices and dedicated to transmissions for the second device.
33. The apparatus of claim 31 or 32, further comprising:
a fifth receiving unit configured to receive an update message of the first virtual cell from the first node.
34. The apparatus of claim 33, wherein the update message comprises at least one of:
a physical identifier of the deleted transmission point;
an updated physical cell identity list; and
physical identifier of the new primary transmission point.
35. The apparatus of claim 31, the apparatus further comprising:
a sixth receiving unit configured to receive, from the first node, an indication as a new master transmission point and updated physical identifiers and reference signal configurations of other transmission points in the first virtual cell, and
a seventh receiving unit configured to receive channel state information feedback from the first device; and
a scheduling unit configured to schedule a transmission from the updated transmission point in the first virtual cell to the first device.
36. The apparatus of claim 35, further comprising:
an eighth receiving unit configured to receive, from the first node, an indication that uplink synchronization with the first device is required, an
A random access control unit configured to cause the first device to initiate random access.
37. The apparatus of claim 35, further comprising:
a ninth receiving unit configured to receive the forwarded data for the first device from an original master transmission point.
38. An apparatus at a first device in a communication system, the communication system comprising a first node, a plurality of transmission points deployed within a coverage area of the first node, and the first device located within the coverage area of the first node, wherein the plurality of transmission points each have a unique physical identifier, the apparatus comprising:
a first receiving unit configured to receive a first virtual cell identifier for a first virtual cell from the first node; the first virtual cell comprises a set of transmission points of the plurality of transmission points, and a first virtual cell identifier is associated with the first device and dedicated to transmissions for the first device;
a second receiving unit configured to receive a configuration message of the first virtual cell from the first node, the configuration message comprising physical identifiers of the set of transmission points in the first virtual cell, a reference symbol configuration, and a master transmission point;
a third receiving unit configured to receive scheduling information from the master transmission point; and
a fourth receiving unit configured to receive data transmitted according to the scheduling message from a transmission point in the first virtual cell.
39. The apparatus of claim 38, further comprising:
a fifth receiving unit configured to receive a measurement configuration from the first node;
a measurement report transmitting unit configured to transmit a measurement report to the first node, the measurement report indicating a result of measurement performed by the first device according to the measurement configuration; and
a sixth receiving unit configured to receive an update message of the first virtual cell from the first node.
40. The apparatus of claim 38, further comprising:
a seventh receiving unit configured to receive an indication from the first node that uplink synchronization with the primary transmission point is required, an
A random access unit configured to initiate an uplink synchronization procedure with the primary transmission point in response to the indication.
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