WO2014019212A1 - Method and apparatus - Google Patents

Method and apparatus Download PDF

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Publication number
WO2014019212A1
WO2014019212A1 PCT/CN2012/079622 CN2012079622W WO2014019212A1 WO 2014019212 A1 WO2014019212 A1 WO 2014019212A1 CN 2012079622 W CN2012079622 W CN 2012079622W WO 2014019212 A1 WO2014019212 A1 WO 2014019212A1
Authority
WO
WIPO (PCT)
Prior art keywords
reference signal
estimation
action
action information
respective reference
Prior art date
Application number
PCT/CN2012/079622
Other languages
French (fr)
Inventor
Xiaoyi Wang
Jingxiu Liu
Original Assignee
Nokia Siemens Networks Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nokia Siemens Networks Oy filed Critical Nokia Siemens Networks Oy
Priority to PCT/CN2012/079622 priority Critical patent/WO2014019212A1/en
Priority to EP12882000.8A priority patent/EP2880892A4/en
Publication of WO2014019212A1 publication Critical patent/WO2014019212A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0032—Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
    • H04L5/0035—Resource allocation in a cooperative multipoint environment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0091—Signaling for the administration of the divided path
    • H04L5/0092—Indication of how the channel is divided
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0023—Time-frequency-space

Definitions

  • a communication system can be seen as a facility that enables communication sessions between two or more entities such as fixed or mobile communication devices, base stations, servers, machine type communication devices and/or other communication nodes.
  • a communication system and compatible communicating entities typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do andhow that should be achieved.
  • the standards, specifications and related protocols can define the manner how various aspects of communication such as access to the communication system and feedbackmessaging shall be implementedbetween communicating devices .
  • a communication can be carried on wired or wireless carriers. In a wireless communication system at least a part of communications between stations occurs over a wireless link.
  • wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems anddifferentwireless localnetworks, forexamplewireless local area networks (WLAN) .
  • PLMN public land mobile networks
  • WLAN wireless local area networks
  • a wireless system can be divided into cells orotherradio coverageorserviceareasprovidedbya station. Radio service areas can overlap, and thus a communication device in an area can send signals to and receive signals from more than one station.
  • 3GPP 3rd Generation Partnership Project
  • LTE long-term evolution
  • UMTS Universal Mobile Telecommunications System
  • LTE-Advanced The various development stages of the 3GPP LTE specifications are referred to as releases.
  • a communication system can be accessed by means of an appropriate communication device.
  • a communication device of a user is often referred to as user equipment (UE) or terminal.
  • UE user equipment
  • a communication device is provided with an alitiste signal receiving and transmitting arrangement for enabling communications with other parties.
  • a communication device is used for enabling receiving and transmission of communications such as speech and data.
  • a communication device provides a transceiver station that can communicate with another
  • a communication device such as e.g. a base station and/or another user equipment.
  • Coordinated Multi-Point Transmission is a technique where combined results of receptionbyapluralityof stations of asignal fromacommunication device (uplink CoMP ⁇ or receptionofa transmissionbasedonsignals transmitted from a plurality of transmission points to a communication (downlink CoMP) canbe utilised.
  • CoMP canbe provided for example in heterogeneous network scenarios.
  • a method comprising: receivingaction information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation,- andperforming an action with respect to said reference signal in dependence on said action information.
  • the reference signal may comprise a channel state information reference signal.
  • the method may comprise receiving action information for reference signals fromapluralityofdifferent transmissionpoints and performing respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
  • Themethod may comprise receiving said reference signals from said plurality of different transmission points.
  • the action information may indicate if a respective reference signal isusedforuplinkco-ordinatedmultipoint estimationand/or downlink co-ordinated multipoint estimation.
  • saidperforming may comprise measuring the received signal received power and/or quality of said respective reference signal.
  • said performing may comprise performing path loss estimation with respect to the respective reference signal.
  • the method may comprise receiving power information associated with said respective reference signal.
  • the power information may comprise energy per resource element for said respective reference signal.
  • the received power information associated with said respective reference signal maybe used to estimate saidpath loss .
  • the action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
  • This method may be performed in an apparatus.
  • the apparatus may be provided in a user equipment.
  • a method comprising: causing action information to be sent to a user equipment, saidactioninformationindicatingif areference signal is to be used for uplink estimation and/or down link estimation; and causing said reference signal to be transmitted to said user equipment.
  • the reference signal may comprise a channel state information reference signal.
  • the action information may indicate if a respective reference signal is used for up link co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
  • the method may comprise causing power information associated with a respective reference signal to be transmitted by a user equipment.
  • the power information may comprise energy per resource element for said respective reference signal.
  • the action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
  • This method may be performed in an apparatus.
  • the apparatus may be provided in a node such as a base station.
  • an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive action information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and perform an action with respect to said reference signal in dependence on said action information.
  • the reference signal may comprise a channel state information reference signal.
  • the at least one memoryand the computer code maybe configured with the at least one processor to cause the apparatus to receive said reference signals from said plurality of different transmission points.
  • the action information may indicate if a respective reference signal isused for up link co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
  • the at least one memory and the computer code maybe configured with the at least one processor to cause the apparatus to, if said action indicates that a respective reference signal is to be used for down link estimation, measure the received signal received power and/or quality of said respective reference signal.
  • the at least onememory and the computer code maybe configured with the at least one processor to cause the apparatus to receive power information associated with said respective reference signal .
  • Thepower information may comprise energy per resource element for said respective reference signal.
  • the at least one memoryand the computer codemaybe configured with the at least one processor to cause the apparatus to estimate said path loss using said received power information associated with said respective reference.
  • the action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
  • an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: cause action information to be sent to a user equipment, said action information indicating if a reference signal is to beused oruplink estimation and/or down link estimation; and cause said reference signal to be transmitted to said user equipment.
  • the re erence signal may comprise a channel state information reference signal.
  • the action information may indicate if a respective reference signal is used for up link co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
  • the at least one memoryand the computer code maybe configured with the at least one processor to cause the apparatus to cause power information associated with a respective reference signal to be transmitted by a user equipment.
  • the power information may comprise energy per resource element for said respective reference signal.
  • the action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
  • an apparatus comprising: means forreceivingaction information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and means for performing an action with respect to said reference signal in dependence on said action information.
  • the reference signal may comprise a channel state information reference signal.
  • the means for receiving may be for receiving action information for reference signals from a plurality of different transmissionpoints and saidperformingmeans maybe forperforming respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
  • the receiving means may be for receiving said reference signals from said plurality of different transmission points.
  • the action information may indicate if a respective reference signal isusedforuplinkco-ordinatedmultipoint estimationand/or downlink co-ordinated multipoint estimation.
  • said performing means may be for measuring the received signal receivedpower and/or quality of said respective reference signal.
  • said performing means may be for performing path loss estimation with respect to the respective reference signal.
  • the receiving means may be for receiving power information associated with said respective reference signal.
  • the power information may comprise energy per resource element for said respective reference signal.
  • the received power information associated with said respective reference signal maybe usedby saidmeans forperforming to estimate said path loss.
  • the action information may comprise a plurality of bits , said action being indicated by a state of the plurality of bits.
  • the apparatus may be provided in a user equipment.
  • an apparatus comprising: means for causing action information to be sent to a user equipment, saidaction informationindicating if a reference signal is to be used for uplink estimation and/or down link estimation; and means for causing said reference signal to be transmitted to said user equipment.
  • the reference signal may comprise a channel state information reference signal.
  • the action information may indicate if a respective reference signal isusedforuplink co-ordinatedmultipointestimationand/or downlink co-ordinated multipoint estimation.
  • the action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
  • the apparatus maybe provided in a node such as a base tation.
  • the apparatuses may be provided and the methods implemented in a user equipment for a communication system and/or a node such as a base station or the like.
  • a computer program comprising program code means adapted to perform the methods may also be provided.
  • Figure 1 show a schematic diagram of a systemwhere some embodiments are applicable
  • Figure 2 shows a schematic diagram of amobile communication device according to some embodiments
  • Figure 3 shows a schematic diagramof a control apparatus according to some embodiments
  • Figure 4 shows a schematic illustration of an embodiment
  • Figure 5 shows a method flow.
  • FIG. 1 shows overlapping access systems or radio service areas 100 and 110 of a cellular system and smaller radio service areas 117 and 119 provided by base stations 106, 107, 118 and 120.
  • the transmission/receptionpoints cancomprisewide areanetworknodes suchas macro eNode B (eNB) whichmay, for example, provide coverage for an entire cell or similar radio service area.
  • Network nodes can also be small or local radio service area network nodes, for example Home eNBs (HeNB) , pico eNodeBs (pico-eNB) , or femto nodes.
  • HeNB Home eNBs
  • pico eNodeBs pico-eNB
  • femto nodes Some applications may utilise radio remote heads (RRH) that are connected to, for example, an eNB.
  • RRH radio remote heads
  • the smaller radio service areas can be located wholly or partially within the larger radio service area.
  • the nodes of the smaller radio service areas may be configured to support local offload.
  • the local nodes can also, for example, be configured to extend the range of a cell .
  • Amobile communication device may thus be located within, and thus communicate with, more than one radio station and the communication devices and stations may have one or more radio channels open at the same time and may send signals to and/or receive signals from more than one source. It is noted that the number of radio service areas and their borders are schematically shown for illustration purposes only in Figure 1. It shall also be understood that the sizes and shapes of radio service areas may vary considerably from the shapes of Figure 1.
  • a base station site can provide one or more cells .
  • a base station can also provide a plurality of sectors, for example three radio sectors, each sector providing a cell or a subarea of a cell. All sectors within a cell can be served by the same base station.
  • Base stations are typically controlled by at least one appropriate controller apparatus so as to enable operation thereof and management of mobile communication devices in communication with the base stations.
  • control apparatus 108 and 109 is shown to control the respective macro level base stations 106 and 107. It is noted that more than one macro level base station may be controlled e.g. by control apparatus 108.
  • the control apparatus of abase station canbe interconnectedwithother control entities .
  • the control apparatus is typically provided with memory capacity andat leastone dataprocessor.
  • the control apparatus andfunctions may be distributed between a plurality of control units.
  • stations 106 and 107 are shown being connected to a wider communications network 113 viagateway 112.
  • Afurther gateway function may be provided to connect to another network.
  • the smaller area stations 118 and 120 can also be connected to the network 113, for example by a separate gateway function and/or via the controllers of the macro level stations.
  • station 118 is connected via a gateway 111 whilst station 120 can provide a remote radio head that connects via the controller apparatus 108.
  • FIG. 2 is a schematic, partially sectioned view of a possible mobile communication device 200 for communication with the stations .
  • a communication device is often re erred to as user equipment (UE) or terminal.
  • An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals.
  • Non-limiting examples include a mobile station (MS) such as a mobile phone or what is known as a ' smart phone' , a portable computer provided with a wireless interface card or other wireless interface facility, personal data assistant (PDA) provided with wireless communication capabilities, or any combinations of these or the like.
  • Amobile communication device mayprovide, for example, communication of data for carrying communications such as voice, electronic mail (email) , text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices.
  • Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet.
  • Non-limiting examples of the content include various downloads, television and radio programs, videos, advertisements, various alerts and other information.
  • the mobile device 200 may receive signals over an air interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals.
  • transceiver apparatus is designated schematically by block 206.
  • the transceiver apparatus 206 may be provided for example bymeans of a radio part and associated antenna arrangement.
  • the antenna arrangement may be arranged internally or externally to the mobile device.
  • a wireless communication device can be provided with a Multiple Input / Multiple Output (MIMO) antenna system.
  • MIMO Multiple Input / Multiple Output
  • a mobile device is also typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications, such as communication of data and control signals with access systems and other communication devices.
  • the apparatus can be adapted to provide measurement to detect and/or select radio points, determination of appropriate radio points and reporting thereof of the embodiments described in more detail below.
  • the data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204.
  • the user maycontrol the operationof themobile devicebymeans of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like.
  • a display 208, a speaker and a microphone can be also provided.
  • a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.
  • Figure 3 shows an example of a control apparatus fora communication system, for example to be coupled to and/or for controlling one or more stations of an access system.
  • base stations comprise the control apparatus.
  • the control apparatus may be an integral part of the base station.
  • the control apparatus can be anothernetwork element .
  • the control apparatus 300 can be arranged to provide control on communications in a service area of the system.
  • the control apparatus can be configured to provide control functions in association with generation and communication of instructions to relevant communication devices andprocessing of responses from the devices and other related information by means of the data processing facility in accordance with certain embodiments described below.
  • the control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input/output interface 304. Viathe interface thecontrol apparatus can be coupled to a receiver and a transmitter of a base station.
  • the control apparatus can be configured to execute an appropriate software code to provide the control functions. It shall be appreciated that similar component can be provided in a control apparatus provided elsewhere in the system for controlling reception of sufficient information for decoding of received information blocks.
  • LTE Long-term evolution
  • UMTS Universal Mobile Telecommunications System
  • 3GPP 3rd Generation Partnership Project
  • appropriate LTE access nodes are a base station of a cellular system, for example what is known as NodeB (NB) in the vocabulary of the 3GPP specifications.
  • NB NodeB
  • the LTE employs a mobile architecture known as the Evolved Universal Terrestrial RadioAccessNetwork (E-UTRAN) .
  • E-UTRAN Evolved Universal Terrestrial RadioAccessNetwork
  • Base stationnodes of suchsystems are known as evolved or enhanced Node Bs (eNBs) and may provide E-UTRAN features such as user plane Radio Link Control/Medium Access Control/Physical layer protocol (RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices .
  • E-UTRAN features such as user plane Radio Link Control/Medium Access Control/Physical layer protocol (RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices .
  • RLC/MAC/PHY Radio Link Control/Medium Access Control/Physical layer protocol
  • RRC Radio Resource Control
  • Other examples of radio access system include those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access) .
  • WLAN wireless local area network
  • WiMax Worldwide Interoperability for Microwave Access
  • a user equipment receives channel state information reference signals (CSI-RS) from two or more transmission points and provides CSI feedback. Where the user equipment is configured to receive a plurality of CSI-RS signals, the user equipment measures each CSI-RS signal and generates CSI feedback corresponding to each of these signals.
  • CSI-RS channel state information reference signals
  • Each of these CSI-RS signals is considered to come from a different transmission point TP.
  • the transmission points may be considered to be a real and/or virtual transmission points. It should be appreciated that the term transmission point refers to a real transmission point or a virtual transmission point.
  • the UE will see a CSI-RS resource representing a TP (physical or virtual) . EachTPmaybe equippedwithmultipleantennaports and/orantennas .
  • a transmission point may be associated with one CSI-RS resource.
  • a CSI-RS resource is a set of parameters configured from the eNB to the userequipment to indicatehowthe CSI-RSwill be transmitted.
  • the CSI-RS signal itself is the signal which is transmitted from the eNB to the UE.
  • a transmission point may be provided by a radio head and/or eNode B.
  • a node may be provided with two or more radio heads .
  • a node may provide one or more transmission points .
  • the received signal received power RSRP of the CSI-RS is measured.
  • the CSI-RS RSRP measurements may be defined as ollows .
  • the reference signal received power is defined as the linear average over the power contributions, in Watts, of the resource elements that carry channel state information reference signals within the considered measurement frequency bandwidth. In other situations, a different definition of the CSI-RS RSRP may be used.
  • the channel state information reference signal R15 (as for example defined in TS 36.211) should be used. If the user equipment can reliably detect that the R16 reference signal is available the user equipment may use the R16 signal in addition to the R15 signal to determine the RSRP.
  • Ports 15 and 16 are UE antenna ports and R15 and R16 are sequences transmitted on the respective ports.
  • An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. There may be one resource grid per antenna port. The set of antenna ports supported may depend on the reference signal configuration in the cell. Some standards, such as LTE had specified a variety of antenna ports for different purposes.
  • Some embodiments may use antenna ports 15 and 16 with associated sequences. However, this is by way of example only and in other embodiments, one or more different antenna ports may be used.
  • the antennaports are a logical concept andmay be physical and/or virtual antenna ports.
  • the size of the CoMP management set which may be used as the potential resource for the CSI-RS RSRP measurement set, has not been defined in standard . However, it shouldbe appreciated that the size of the measurement set may be any suitable size. By way of example, the CoMP management set may be set to 16, which is the size of the neighbour cell list in 3GPP release 8.
  • the uplink power control required is per node path loss estimation.
  • theuserequipment shouldbeable tomeasure the per node path loss based on for example the down link CSI-RS RSRP measurement.
  • some information is unavailable to the user equipment.
  • the transmission point transmitting the CSI-RS may only be able to do downlink transmission to the user equipment but not perform uplink reception.
  • the down link CSI-RS configuration does not transmit power informationwithwhich transmissionpoints transmit.
  • general power information may be sent to the user equipment via SIB (system information block) information.
  • SIB system information block
  • the user equipment may not be able to estimate the path loss f om the Pico cell to the user equipment.
  • the down link CSI-RS configuration is transparent to the receiverof a CSI-RS signal. Accordingly, there is a problem with current proposals in that the limited information about downlink transmissionpoints means that the user equipment does not know which CSI-RS signal should be used for the estimation of path loss for uplink open loop power control for uplink transmission to one or more of the downlink transmission points nor have the necessary information in order to determine path loss for uplink power control.
  • the CSI reference signal is received in each physical antenna port or virtualized antenna port and is used for measurement purposes only
  • a cell can be configured with one, two, four or eight CSI-RS. In other embodiments, a different number or CSI-RS may be used.
  • the CSI-RS structure including the set of resource elements used for CSI-RS in a resource block, may depend on the number of CSI-RS configuredwithinthe cell andmaybedifferent for different cells . More specifically, within a resource-block pair there may be for example 40 possible positions for the reference symbols of CSI-RS and, in a given cell, a subset of corresponding resource elements is used for CSI-RS transmission.
  • the UE may have no information about the transmission point. . A UE may not be able to know from which transmission point a CSI-RS has been received. The UE will measure the CSI-RS and provide a report.
  • the node transmitting the CSI-RS may be a physical transmission point or a virtual transmission point.
  • the transmissionpoints are transparent to UE.
  • Each UE is configured with several CSI-RS resources, The UE measures the channel response for each CSI-RS signal and feeds back CSI.
  • Each CSI-RS resource may correspond to a transmission point.
  • an eNB is able to transmit the same CSI-RS on several transmission points TP.
  • a UE may not know which transmission point will receive uplink transmissions from the UE.
  • a UE does not know which CSI-RS signal should be used for estimation of path loss for UL open loop power control.
  • some transmission points may not be used to receive uplink signals fromUE, and some will.
  • the UE will be given information about which of the transmission nodes will receive UL signals from the UE. This means that the UE can adjust its transmission power towards the correct transmission point (s) .
  • a CSI-RS resource configuration method is provided to support a generic framework of RSRP reports and path loss estimation.
  • the configuration of the CSI-RS resource includes at least one of transmission power and related action.
  • information which is required to calculate power loss may be provided.
  • This information may comprise the down link transmission power of each downlink transmission point (for example, EPRP - energy per resource element) .
  • the transmission power may indicate the absolute or relative EPRE.
  • the transmission power may consist of an absolute part and/or a relative part EPRE of the CSI-resource.
  • the related action may indicate whether the user equipment should measure the RSRP and/or the path loss for that signal .
  • the relevant action may indicate one of the following actions: the current CSI-RS signal is only used for down link RSRP estimation, the current CSI-RS signal is only used for path loss estimation for uplink open loop power control; and/or the current CSI-RS signal is used for both downlink RSRP estimation and uplink open loop power control path loss estimation.
  • transmission power per transmission point may be transmitted to the UE from the transmission point or other node.
  • signaling per transmission point may be sufficient for determining the "aggregated" path loss to the nodes associated with the transmission point.
  • the EPRE for each node associated with each CSI-RS resource
  • UE can estimate the path loss of each node using the EPRE information and the information about the power with which the CSI-RS signal is received. Such path loss may be used to determine the uplink transmission power to be used by the UE.
  • the action may be signalled using for example two bits. Accordingly, the three above-mentioned options may be signalled using different combination of the two bits .
  • the unused combination of two bits may be reserved.
  • one implementation may be as follows.
  • the CSI-RS symbols are used forchannel state information functions such as channel quality information, PMI (precoding matrix index) and RI (rank indicator) measurement and reporting.
  • CSI-RS may be transmitted periodically.
  • the periodicityof the CSI-RS maybe configurablewithduty cyclevalues for example ranging between 5 ms to 80 ms.
  • the CSI-RS are received by a user equipment .
  • the user equipment will estimate the channel state information based on the CSI-RS and transmit feedback to one or more base stations.
  • the base stations may be associated with one or more transmission points.
  • the base stations can use theCSI feedback inthe selectionofparameters suchas thepre-coder and modulation and coding scheme for the data.
  • a user equipment 400 is associated with a macro cell 402 and a pico cell 401 with a first remote radio head 404 and a second remote radio head 406. As shown in figure 4, there are three CSI-RS signals, CSI-RS1, CSI-RS2 and CSI-RS3, one associated with each of the macro cell and the two radio heads . Each of the macro cell and two radio heads are examples of transmission points.
  • step SI the radio resource control configures the CSI-RS resources andadds the informationassociated with the related action.
  • the information on action associated with a particular CSI-RS resource is transmitted along with the CSI-RS configuration by a base station.
  • the signalling of the CSI-RS resource from the e B is RRC signalling. This signalling may be providedbythe base stationforapluralityof transmissionpoints. Alternatively or additionally, the RRC signalling may be provided by a plurality of nodes which may be base stations.
  • step S2 the user equipment receives the RRC configuration for the CSI-RS resource.
  • step S3 the CSI RS signals from the plurality of transmission points are received by the user equipment.
  • step S4 the user equipment will carry out the related action associated with each CSI-RS signal. As mentioned previously, these actions will depend on what the CSI-RS signal is used for. It shouldbe appreciated that eachCSI-RS transmissionwill include transmission power information which may be used to carry out the related action. Alternatively or additionally, the transmission power may be included in the RRC configuration information.
  • step S5 if the related action indicates that signal is used for down link RSRP estimation, the user equipment may provide the necessary feedback to the transmission point. For example, if the signal is used for down link RSRP estimation, then this informationwill be sentback to the associatedtransmissionpoint. In alternative embodiments, the feedback may be provided to a node such as a base station which may be different to the transmission point (s) .
  • step S6 if the CSI-RS signal is used for path loss estimation for uplink open loop power control, then the user equipment will use the transmission power in order to estimate the power loss for uplink open loop power control. The user equipment will then use the path loss estimation to control the power with which the user equipment transmits to the transmission point . Steps S5 and S6 may be alternatives , take place at the same time or take place in either order.
  • the RRC configuration of the CSI-resource will provide information about which CSI-RS is used for down link CoMP, which is used for uplink-CoMP and which is used for both down link and uplink CoMP.
  • the power control may not necessarily be open loop power control and may for example be closed loop power control.
  • the reference signal received power is determined.
  • an alternative characteristic of the received reference signal maybe determined.
  • the reference signal received quality may alternatively or additionally be determined.
  • the reference signal used is the CSI-RS. It should be appreciated that in other embodiments, different reference signals may be used. Embodiments may be used with different standards or different versions of the standards mentioned previously.
  • the method of Figure 5 may be at least partially carried out by a UE. For example at least some of the method may be carried out by separate processors or by an integrated processor.
  • the data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) , application specific integrated circuits (ASIC) , gate level circuits and processors based onmulti core processor architecture as non-limiting examples.
  • the data processing may be distributed across several data processing modules .
  • a data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity canalso be provided in the relevant devices .
  • the memory or memories may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor basedmemorydevices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.
  • Anappropriatelyadapted computer program code product or products may be used for implementing the embodiments, when loaded or otherwise provided on an appropriate data processing apparatus .
  • the program code product for providing the operation may be stored on, providedandembodiedbymeans ofanappropriate carriermedium.
  • An appropriate computer program can be embodied on a computer readable record medium. A possibility is to download the program codeproduct viaadatanetwork.
  • thevarious embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof.
  • Embodiments of the inventions may be practiced in various components such as integrated circuit modules.
  • the design of integrated circuits is by and large an automated process. Complex and powerful tools are available for converting a logic level design into a semiconductor circuit design ready to be formed on a semiconductor substrate.

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Abstract

A method comprises receiving action information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation and performing an action with respect to said reference signal in dependence on said action information.

Description

METHOD AND APPARATUS This disclosure relates to amethod and apparatus and inparticular but not exclusively to a method and apparatus usable in a context of a coordinated multipoint transmission arrangement.
A communication system can be seen as a facility that enables communication sessions between two or more entities such as fixed or mobile communication devices, base stations, servers, machine type communication devices and/or other communication nodes. A communication system and compatible communicating entities typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do andhow that should be achieved. For example, the standards, specifications and related protocols can define the manner how various aspects of communication such as access to the communication system and feedbackmessaging shall be implementedbetween communicating devices . A communication can be carried on wired or wireless carriers. In a wireless communication system at least a part of communications between stations occurs over a wireless link.
Examples of wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems anddifferentwireless localnetworks, forexamplewireless local area networks (WLAN) . A wireless system can be divided into cells orotherradio coverageorserviceareasprovidedbya station. Radio service areas can overlap, and thus a communication device in an area can send signals to and receive signals from more than one station. A more detailed example of wireless systems is an architecture standardized by the 3rd Generation Partnership Project (3GPP) and referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. A further development of the LTE is often referred to as LTE-Advanced. The various development stages of the 3GPP LTE specifications are referred to as releases.
A communication system can be accessed by means of an appropriate communication device. A communication device of a user is often referred to as user equipment (UE) or terminal. A communication device is provided with an a propriate signal receiving and transmitting arrangement for enabling communications with other parties. Typically a communication device is used for enabling receiving and transmission of communications such as speech and data. In wireless systems a communication device provides a transceiver station that can communicate with another
communication device such as e.g. a base station and/or another user equipment.
More advanced transmission schemes become increasingly desirable with the technical evolution. For example, it has been proposed that a UE may communicate simultaneously to multiple nodes. Multipoint schemes such as Coordinated Multi-Point Transmission (CoMP) have been proposed to provide this . Coordinated multipoint transmission (CoMP) is a technique where combined results of receptionbyapluralityof stations of asignal fromacommunication device (uplink CoMP} or receptionofa transmissionbasedonsignals transmitted from a plurality of transmission points to a communication (downlink CoMP) canbe utilised. CoMP canbe provided for example in heterogeneous network scenarios.
According to an embodiment, there is provided a method comprising: receivingaction information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation,- andperforming an action with respect to said reference signal in dependence on said action information.
The reference signal may comprise a channel state information reference signal.
The method may comprise receiving action information for reference signals fromapluralityofdifferent transmissionpoints and performing respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
Themethodmay comprise receiving said reference signals from said plurality of different transmission points.
The action informationmay indicate if a respective reference signal isusedforuplinkco-ordinatedmultipoint estimationand/or downlink co-ordinated multipoint estimation.
If said action indicates that a respective reference signal is to be used for downlink estimation, saidperformingmay comprise measuring the received signal received power and/or quality of said respective reference signal.
If said action information indicates that a respective reference signal is to be used for uplink estimation, said performing may comprise performing path loss estimation with respect to the respective reference signal.
The method may comprise receiving power information associated with said respective reference signal.
The power information may comprise energy per resource element for said respective reference signal.
The received power information associated with said respective reference signal maybe used to estimate saidpath loss .
The action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
This method may be performed in an apparatus. The apparatus may be provided in a user equipment.
According to another aspect, there is provided a method comprising: causing action information to be sent to a user equipment, saidactioninformationindicatingif areference signal is to be used for uplink estimation and/or down link estimation; and causing said reference signal to be transmitted to said user equipment.
The reference signal may comprise a channel state information reference signal.
The action informationmay indicate if a respective reference signal is used for up link co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
The methodmay comprise causing power information associated with a respective reference signal to be transmitted by a user equipment.
The power information may comprise energy per resource element for said respective reference signal.
The action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
This method may be performed in an apparatus. The apparatus may be provided in a node such as a base station.
According to another embodiment, there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive action information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and perform an action with respect to said reference signal in dependence on said action information.
The reference signal may comprise a channel state information reference signal.
The at least one memoryand the computer codemaybe configured with the at least one processor to cause the apparatus to receive action information for reference signals from a plurality of different transmission points and to perform respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
The at least one memoryand the computer code maybe configured with the at least one processor to cause the apparatus to receive said reference signals from said plurality of different transmission points.
The action information may indicate if a respective reference signal isused for up link co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
The at least one memory and the computer code maybe configured with the at least one processor to cause the apparatus to, if said action indicates that a respective reference signal is to be used for down link estimation, measure the received signal received power and/or quality of said respective reference signal.
The at least one memory and the computer codemaybe configured with the at least one processor to cause the apparatus to, if said action information indicates that a respective reference signal is to be used for uplink estimation, perform path loss estimation with respect to the respective reference signal.
The at least onememory and the computer code maybe configured with the at least one processor to cause the apparatus to receive power information associated with said respective reference signal . Thepower information may comprise energy per resource element for said respective reference signal.
The at least one memoryand the computer codemaybe configured with the at least one processor to cause the apparatus to estimate said path loss using said received power information associated with said respective reference.
The action informationmay comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
According to another embodiment, there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: cause action information to be sent to a user equipment, said action information indicating if a reference signal is to beused oruplink estimation and/or down link estimation; and cause said reference signal to be transmitted to said user equipment.
The re erence signal may comprise a channel state information reference signal.
The action informationmay indicate if a respective reference signal is used for up link co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
The at least one memoryand the computer code maybe configured with the at least one processor to cause the apparatus to cause power information associated with a respective reference signal to be transmitted by a user equipment.
The power information may comprise energy per resource element for said respective reference signal.
The action information may comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
According to another embodiment, there is provided an apparatus comprising: means forreceivingaction information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and means for performing an action with respect to said reference signal in dependence on said action information.
The reference signal may comprise a channel state information reference signal. The means for receiving may be for receiving action information for reference signals from a plurality of different transmissionpoints and saidperformingmeans maybe forperforming respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
The receiving means may be for receiving said reference signals from said plurality of different transmission points.
The action informationmay indicate if a respective reference signal isusedforuplinkco-ordinatedmultipoint estimationand/or downlink co-ordinated multipoint estimation.
If said action indicates that a respective reference signal is to be used for downlink estimation, said performing means may be for measuring the received signal receivedpower and/or quality of said respective reference signal.
If said action information indicates that a respective reference signal is to be used for uplink estimation, said performing means may be for performing path loss estimation with respect to the respective reference signal.
The receiving means may be for receiving power information associated with said respective reference signal.
The power information may comprise energy per resource element for said respective reference signal.
The received power information associated with said respective reference signalmaybe usedby saidmeans forperforming to estimate said path loss.
The action information may comprise a plurality of bits , said action being indicated by a state of the plurality of bits.
The apparatus may be provided in a user equipment.
According to another aspect, there is provided an apparatus comprising: means for causing action information to be sent to a user equipment, saidaction informationindicating if a reference signal is to be used for uplink estimation and/or down link estimation; and means for causing said reference signal to be transmitted to said user equipment.
The reference signal may comprise a channel state information reference signal. The action informationmay indicate if a respective reference signal isusedforuplink co-ordinatedmultipointestimationand/or downlink co-ordinated multipoint estimation.
Theapparatusmaycompr semeans forcausingpowerinformation associated with a respective reference signal to be transmitted by a user equipment.
Thepowerinformationmaycompriseenergyperresource element for said respective reference signal.
The action informationmay comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
The apparatus maybe provided in a node such as a base tation.
The apparatuses may be provided and the methods implemented in a user equipment for a communication system and/or a node such as a base station or the like.
A computer program comprising program code means adapted to perform the methods may also be provided.
Various other aspects and further embodiments are also described in the following detaileddescriptionand inthe attached claims .
Different aspects from may be combined in part or in full.
Embodiments will now be described in further detail, by way of example only, with reference to the following examples and accompanying drawings, in which:
Figure 1 showa schematic diagram of a systemwhere some embodiments are applicable;
Figure 2 shows a schematic diagram of amobile communication device according to some embodiments;
Figure 3 shows a schematic diagramof a control apparatus according to some embodiments;
Figure 4 shows a schematic illustration of an embodiment; and Figure 5 shows a method flow.
Certain exemplifying embodiments are explained below with reference to a wireless or mobile communication system serving mobile communication devices. Before explaining in detail the exemplifying embodiments, certaingeneralprinciples of awireless communication system andmobile communication devices are briefly explainedwithreference toFigures 1 to 3 toassist inunderstanding the technology underlying the described examples. In a wireless communication system mobile communication devices or user equipment (UE) 102 are provided wireless access via at least one base station or similar wireless transmitting and/or receiving node or point . The example of Figure 1 shows overlapping access systems or radio service areas 100 and 110 of a cellular system and smaller radio service areas 117 and 119 provided by base stations 106, 107, 118 and 120. For example, in the LTE the transmission/receptionpoints cancomprisewide areanetworknodes suchas macro eNode B (eNB) whichmay, for example, provide coverage for an entire cell or similar radio service area. Network nodes can also be small or local radio service area network nodes, for example Home eNBs (HeNB) , pico eNodeBs (pico-eNB) , or femto nodes. Some applications may utilise radio remote heads (RRH) that are connected to, for example, an eNB. The smaller radio service areas can be located wholly or partially within the larger radio service area. The nodes of the smaller radio service areasmay be configured to support local offload. The local nodes can also, for example, be configured to extend the range of a cell . Amobile communication device may thus be located within, and thus communicate with, more than one radio station and the communication devices and stations may have one or more radio channels open at the same time and may send signals to and/or receive signals from more than one source. It is noted that the number of radio service areas and their borders are schematically shown for illustration purposes only in Figure 1. It shall also be understood that the sizes and shapes of radio service areas may vary considerably from the shapes of Figure 1. A base station site can provide one or more cells . A base station can also provide a plurality of sectors, for example three radio sectors, each sector providing a cell or a subarea of a cell. All sectors within a cell can be served by the same base station. Base stations are typically controlled by at least one appropriate controller apparatus so as to enable operation thereof and management of mobile communication devices in communication with the base stations. In Figure 1 control apparatus 108 and 109 is shown to control the respective macro level base stations 106 and 107. It is noted that more than one macro level base station may be controlled e.g. by control apparatus 108. The control apparatus of abase stationcanbe interconnectedwithother control entities . The control apparatus is typically provided with memory capacity andat leastone dataprocessor. The control apparatus andfunctions may be distributed between a plurality of control units.
In Figure 1 stations 106 and 107 are shown being connected to a wider communications network 113 viagateway 112. Afurther gateway functionmay be provided to connect to another network. The smaller area stations 118 and 120 can also be connected to the network 113, for example by a separate gateway function and/or via the controllers of the macro level stations. In the example, station 118 is connected via a gateway 111 whilst station 120 can provide a remote radio head that connects via the controller apparatus 108.
Figure 2 is a schematic, partially sectioned view of a possible mobile communication device 200 for communication with the stations . Such a communication device is often re erred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) such as a mobile phone or what is known as a ' smart phone' , a portable computer provided with a wireless interface card or other wireless interface facility, personal data assistant (PDA) provided with wireless communication capabilities, or any combinations of these or the like. Amobile communication device mayprovide, for example, communication of data for carrying communications such as voice, electronic mail (email) , text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Non-limiting examples of the content include various downloads, television and radio programs, videos, advertisements, various alerts and other information. The mobile device 200 may receive signals over an air interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example bymeans of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device. A wireless communication device can be provided with a Multiple Input / Multiple Output (MIMO) antenna system.
A mobile device is also typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications, such as communication of data and control signals with access systems and other communication devices. The apparatus can be adapted to provide measurement to detect and/or select radio points, determination of appropriate radio points and reporting thereof of the embodiments described in more detail below. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user maycontrol the operationof themobile devicebymeans of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto. Figure 3 shows an example of a control apparatus fora communication system, for example to be coupled to and/or for controlling one or more stations of an access system. In some embodiments base stations comprise the control apparatus. The control apparatus may be an integral part of the base station. In other embodiments the control apparatus can be anothernetwork element . The control apparatus 300 can be arranged to provide control on communications in a service area of the system. The control apparatus can be configured to provide control functions in association with generation and communication of instructions to relevant communication devices andprocessing of responses from the devices and other related information by means of the data processing facility in accordance with certain embodiments described below. For this purpose the control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input/output interface 304. Viathe interface thecontrol apparatus can be coupled to a receiver and a transmitter of a base station. The control apparatus can be configured to execute an appropriate software code to provide the control functions. It shall be appreciated that similar component can be provided in a control apparatus provided elsewhere in the system for controlling reception of sufficient information for decoding of received information blocks.
Anon-limiting example of the recent developments in communication system architectures is the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) that is being standardized by the 3rd Generation Partnership Project (3GPP) . Non-limiting examples of appropriate LTE access nodes are a base station of a cellular system, for example what is known as NodeB (NB) in the vocabulary of the 3GPP specifications. The LTE employs a mobile architecture known as the Evolved Universal Terrestrial RadioAccessNetwork (E-UTRAN) . Base stationnodes of suchsystems are known as evolved or enhanced Node Bs (eNBs) and may provide E-UTRAN features such as user plane Radio Link Control/Medium Access Control/Physical layer protocol (RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices . Other examples of radio access system include those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access) .
In some CoMP arrangements, a user equipment receives channel state information reference signals (CSI-RS) from two or more transmission points and provides CSI feedback. Where the user equipment is configured to receive a plurality of CSI-RS signals, the user equipment measures each CSI-RS signal and generates CSI feedback corresponding to each of these signals.
Each of these CSI-RS signals is considered to come from a different transmission point TP. The transmission points may be considered to be a real and/or virtual transmission points. It should be appreciated that the term transmission point refers to a real transmission point or a virtual transmission point. The UE will see a CSI-RS resource representing a TP (physical or virtual) . EachTPmaybe equippedwithmultipleantennaports and/orantennas . A transmission point may be associated with one CSI-RS resource. A CSI-RS resource is a set of parameters configured from the eNB to the userequipment to indicatehowthe CSI-RSwill be transmitted. The CSI-RS signal itself is the signal which is transmitted from the eNB to the UE.
A transmission point may be provided by a radio head and/or eNode B. For example a node may be provided with two or more radio heads . A node may provide one or more transmission points . The received signal received power RSRP of the CSI-RS is measured. The CSI-RS RSRP measurements may be defined as ollows . The reference signal received power is defined as the linear average over the power contributions, in Watts, of the resource elements that carry channel state information reference signals within the considered measurement frequency bandwidth. In other situations, a different definition of the CSI-RS RSRP may be used.
It has been proposed that the channel state information reference signal R15 (as for example defined in TS 36.211) should be used. If the user equipment can reliably detect that the R16 reference signal is available the user equipment may use the R16 signal in addition to the R15 signal to determine the RSRP. Ports 15 and 16 are UE antenna ports and R15 and R16 are sequences transmitted on the respective ports. An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. There may be one resource grid per antenna port. The set of antenna ports supported may depend on the reference signal configuration in the cell. Some standards, such as LTE had specified a variety of antenna ports for different purposes. Some embodiments may use antenna ports 15 and 16 with associated sequences. However, this is by way of example only and in other embodiments, one or more different antenna ports may be used. The antennaports are a logical concept andmay be physical and/or virtual antenna ports. The size of the CoMP management set, which may be used as the potential resource for the CSI-RS RSRP measurement set, has not been defined in standard . However, it shouldbe appreciated that the size of the measurement set may be any suitable size. By way of example, the CoMP management set may be set to 16, which is the size of the neighbour cell list in 3GPP release 8.
In uplink CoMP, the uplink power control required is per node path loss estimation. Thus, theuserequipment shouldbeable tomeasure the per node path loss based on for example the down link CSI-RS RSRP measurement. However, with current proposals, some information is unavailable to the user equipment. For example, the transmission point transmitting the CSI-RS may only be able to do downlink transmission to the user equipment but not perform uplink reception. Further, the down link CSI-RS configuration does not transmit power informationwithwhich transmissionpoints transmit. In current homogenous networks proposals, general power informationmay be sent to the user equipment via SIB (system information block) information. However, in the current HetNet proposals, the transmission power of for example a Pico cell is not signalled by the SIB. Without such information, the user equipment may not be able to estimate the path loss f om the Pico cell to the user equipment. In other words, currently, the down link CSI-RS configuration is transparent to the receiverof a CSI-RS signal. Accordingly, there is a problem with current proposals in that the limited information about downlink transmissionpoints means that the user equipment does not know which CSI-RS signal should be used for the estimation of path loss for uplink open loop power control for uplink transmission to one or more of the downlink transmission points nor have the necessary information in order to determine path loss for uplink power control.
The CSI reference signal is received in each physical antenna port or virtualized antenna port and is used for measurement purposes only
A cell can be configured with one, two, four or eight CSI-RS. In other embodiments, a different number or CSI-RS may be used. The CSI-RS structure, including the set of resource elements used for CSI-RS in a resource block, may depend on the number of CSI-RS configuredwithinthe cell andmaybedifferent for different cells . More specifically, within a resource-block pair there may be for example 40 possible positions for the reference symbols of CSI-RS and, in a given cell, a subset of corresponding resource elements is used for CSI-RS transmission. The UE may have no information about the transmission point. . A UE may not be able to know from which transmission point a CSI-RS has been received. The UE will measure the CSI-RS and provide a report. As mentioned previously, the node transmitting the CSI-RS may be a physical transmission point or a virtual transmission point.
In someversions of the standards, forCoMP, the transmissionpoints are transparent to UE. Each UE is configured with several CSI-RS resources, The UE measures the channel response for each CSI-RS signal and feeds back CSI. Each CSI-RS resource may correspond to a transmission point. In some situations, an eNB is able to transmit the same CSI-RS on several transmission points TP. With current proposals, a UE may not know which transmission point will receive uplink transmissions from the UE. Thus a UE does not know which CSI-RS signal should be used for estimation of path loss for UL open loop power control.
In some embodiments some transmission points may not be used to receive uplink signals fromUE, and some will. In some embodiments, the UE will be given information about which of the transmission nodes will receive UL signals from the UE. This means that the UE can adjust its transmission power towards the correct transmission point (s) .
In some embodiments, a CSI-RS resource configuration method is provided to support a generic framework of RSRP reports and path loss estimation. The configuration of the CSI-RS resource includes at least one of transmission power and related action. Thus in some scenarios, information which is required to calculate power loss may be provided. This information may comprise the down link transmission power of each downlink transmission point (for example, EPRP - energy per resource element) . The transmission power may indicate the absolute or relative EPRE. The transmission power may consist of an absolute part and/or a relative part EPRE of the CSI-resource. The related action may indicate whether the user equipment should measure the RSRP and/or the path loss for that signal . The relevant actionmay indicate one of the following actions: the current CSI-RS signal is only used for down link RSRP estimation, the current CSI-RS signal is only used for path loss estimation for uplink open loop power control; and/or the current CSI-RS signal is used for both downlink RSRP estimation and uplink open loop power control path loss estimation.
Thus information about transmission power per transmission point may be transmitted to the UE from the transmission point or other node. In some embodiments, signaling per transmission point may be sufficient for determining the "aggregated" path loss to the nodes associated with the transmission point. Thus in some embodiments, the EPRE for each node (associated with each CSI-RS resource) may be signaled. Therefore UE can estimate the path loss of each node using the EPRE information and the information about the power with which the CSI-RS signal is received. Such path loss may be used to determine the uplink transmission power to be used by the UE.
In some embodiments , the action may be signalled using for example two bits. Accordingly, the three above-mentioned options may be signalled using different combination of the two bits . The unused combination of two bits may be reserved. By way of example only, one implementation may be as follows.
00: current CSI-RS resource is only used for DL RSRP estimation;
01: current CSI-RS resource is only used for path loss estimation for UL open loop power control
10: current CSI-RS resource is usedforbothDLRSRP estimation and UL open loop PC path loss estimation
11: reserved.
It should be appreciated that this is by way of example only and different bit combinations may be used for different options. The CSI-RS symbols are used forchannel state information functions such as channel quality information, PMI (precoding matrix index) and RI (rank indicator) measurement and reporting. CSI-RS may be transmitted periodically. In some embodiments, the periodicityof the CSI-RSmaybe configurablewithduty cyclevalues for example ranging between 5 ms to 80 ms. The CSI-RS are received by a user equipment . The user equipment will estimate the channel state information based on the CSI-RS and transmit feedback to one or more base stations. The base stations may be associated with one or more transmission points. The base stations can use theCSI feedback inthe selectionofparameters suchas thepre-coder and modulation and coding scheme for the data.
Reference is made to figure 4. A user equipment 400 is associated with a macro cell 402 and a pico cell 401 with a first remote radio head 404 and a second remote radio head 406. As shown in figure 4, there are three CSI-RS signals, CSI-RS1, CSI-RS2 and CSI-RS3, one associated with each of the macro cell and the two radio heads . Each of the macro cell and two radio heads are examples of transmission points.
Reference is made to figure 5 which shows amethod flow inaccordance with an embodiment. In step SI, the radio resource control configures the CSI-RS resources andadds the informationassociated with the related action. The information on action associated with a particular CSI-RS resource is transmitted along with the CSI-RS configuration by a base station. The signalling of the CSI-RS resource from the e B is RRC signalling. This signalling may be providedbythe base stationforapluralityof transmissionpoints. Alternatively or additionally, the RRC signalling may be provided by a plurality of nodes which may be base stations.
In step S2, the user equipment receives the RRC configuration for the CSI-RS resource.
In step S3, the CSI RS signals from the plurality of transmission points are received by the user equipment.
In step S4, the user equipment will carry out the related action associated with each CSI-RS signal. As mentioned previously, these actions will depend on what the CSI-RS signal is used for. It shouldbe appreciated that eachCSI-RS transmissionwill include transmission power information which may be used to carry out the related action. Alternatively or additionally, the transmission power may be included in the RRC configuration information.
In step S5, if the related action indicates that signal is used for down link RSRP estimation, the user equipment may provide the necessary feedback to the transmission point. For example, if the signal is used for down link RSRP estimation, then this informationwill be sentback to the associatedtransmissionpoint. In alternative embodiments, the feedback may be provided to a node such as a base station which may be different to the transmission point (s) . In step S6, if the CSI-RS signal is used for path loss estimation for uplink open loop power control, then the user equipment will use the transmission power in order to estimate the power loss for uplink open loop power control. The user equipment will then use the path loss estimation to control the power with which the user equipment transmits to the transmission point . Steps S5 and S6 may be alternatives , take place at the same time or take place in either order.
Thus, in embodiments of the invention, the RRC configuration of the CSI-resource will provide information about which CSI-RS is used for down link CoMP, which is used for uplink-CoMP and which is used for both down link and uplink CoMP.
In embodiments, reference has been made to path loss estimation for uplink open loop power control . It should be appreciated that alternatively or additionally, alternative methods of
measurements may be used for power control. The power control may not necessarily be open loop power control and may for example be closed loop power control.
The embodiments discussed above may alternatively or be additionally used other than for CoMP.
In the above described embodiments, the reference signal received power is determined. Alternatively or additionally an alternative characteristic of the received reference signal maybe determined. For example, the reference signal received quality may alternatively or additionally be determined.
In the above embodiments, the reference signal used is the CSI-RS. It should be appreciated that in other embodiments, different reference signals may be used. Embodiments may be used with different standards or different versions of the standards mentioned previously.
The method of Figure 5 may be at least partially carried out by a UE. For example at least some of the method may be carried out by separate processors or by an integrated processor. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) , application specific integrated circuits (ASIC) , gate level circuits and processors based onmulti core processor architecture as non-limiting examples. The data processing may be distributed across several data processing modules . A data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity canalso be provided in the relevant devices . The memory or memories may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor basedmemorydevices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. Anappropriatelyadapted computer program code product or products may be used for implementing the embodiments, when loaded or otherwise provided on an appropriate data processing apparatus . The program code product for providing the operation may be stored on, providedandembodiedbymeans ofanappropriate carriermedium. An appropriate computer program can be embodied on a computer readable record medium. A possibility is to download the program codeproduct viaadatanetwork. Ingeneral, thevarious embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large an automated process. Complex and powerful tools are available for converting a logic level design into a semiconductor circuit design ready to be formed on a semiconductor substrate.
It is noted that whilst embodiments have been described in relation toLTE, similarprinciples canbe applied toanyother communication systemwhere dynamic feedbackmessagingmaybe desired. Therefore, although certainembodiments were describedabove bywayof example with reference to certain exemplifying architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.
The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations maybecome apparent to those skilled in the relevant arts in view of the foregoing description, when readin conjunction with the accompanyingdrawings and the appended claims. For example, a combination of one or more of any of the other embodiments previously discussed can be provided. All such and similar modifications of the teachings of this invention will still fall within the scope of this invention as defined in the appended claims.

Claims

What is claimed Is:
1. A method comprising:
receiving action information, said action information indicating if a reference signal is tobe used foruplinkestimation and/or down link estimation; and
performing an action with respect to said reference signal in dependence on said action information.
2. A method as claimed in claim 1, wherein said reference signal comprises a channel state information reference signal.
3. A method as claimed in claim 1 or 2, comprising receiving action information for reference signals from a plurality of different transmission points and performing respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
4. A method as claimed in claim 3, comprising receiving said reference signals from said plurality of different transmission points .
5. A method as claimed in claim 3 or 4, wherein said action information indicates if a respective reference signal is used for uplink co-ordinated multipoint estimation and/or downlink co-ordinated multipoint estimation.
6. A method as claimed in any preceding claim, wherein if said action indicates that a respective reference signal is to be used for downlink estimation, said performing comprises measuring the received signal received power and/or quality of said respective reference signal.
7. A method as claimed in any preceding claim, wherein if said action information indicates that a respective reference signal is to be used for uplink estimation, said performing comprises performing path loss estimation with respect to the respective reference signal.
8. A method as claimed in any preceding claim, comprising receiving power information associated with said respective reference signal.
9. Άmethod as claimed in claim 8, wherein said power information comprises energyperresource element for said respective reference signal.
10. A method as claimed in claim 7 and claim 8 or 9, wherein said received power information associated with said respective reference signal is used to estimate said path loss.
11 Amethodas claimed inanyprecedingclaim, wherein saidaction information comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
12. A method comprising:
Causing action information to be sent to a user equipment, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and Causing said reference signal to be transmitted to said user equipment.
13. A computer program comprising code means configured to perform the steps of any preceding claim when the program is run on a processor.
14. Apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive action information, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and
perform an action with respect to said reference signal in dependence on said action information.
15. Apparatus as claimed in claim 14 , wherein said reference signal comprises a channel state information reference signal.
16. Apparatus as claimed in claim 14 or 15, wherein the at least one memory and the computer code are configured with the at least one processor to cause the apparatus to receive action information for reference signals from a plurality of different transmission points and to perform respective actions on said respective reference signals from said different transmission sources in dependence on said respective action information.
17. Apparatus as claimed in any of claims 14 to 16, wherein the at least one memory and the computer code are configured with the at least one processor to cause the apparatus to receive said reference signals from said plurality of different transmission points .
18. Apparatus as claimed in any of claims 14 to 17, wherein said action information indicates if a respective reference signal is used for up link co-ordinated multipoint estimation and/or down link co-ordinated multipoint estimation.
19. An apparatus as claimed in any of claims 14 to 18, wherein the at least one memory and the computer code are configured with the at least one processor to cause the apparatus to, if said action indicates that a respective reference signal is to be used for downlink estimation, measure the received signal received power and/or quality of said respective reference signal.
20. An apparatus as claimed in any of claims 14 to 19, wherein the at least one memory and the computer code are configured with the at least one processor to cause the apparatus to, if said action information indicates that a respective reference signal is to be used for uplink estimation, perform path loss estimation with respect to the respective reference signal.
21. An apparatus as claimed in any of claims 14 to 20, wherein the at least one memory and the computer code are configured with the at least one processor to cause the apparatus to receive power information associated with said respective reference signal.
22. An apparatus as claimed in claim 21, wherein said power information comprises energy per resource element for said respective reference signal.
23. Anapparatus as claimed inclaim 20 and claim21 or 22, wherein the at least one memory and the computer code are configured with the at least one processor to cause the apparatus to estimate said path loss using said received power information associated with said respective reference.
24. An apparatus as claimed in any of claims 14 to 23, wherein said action information comprise a plurality of bits, said action being indicated by a state of the plurality of bits.
25. Apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:
cause action information to be sent to a user equipment, said action information indicating if a reference signal is to be used for uplink estimation and/or down link estimation; and
cause said reference signal to be transmitted to said user equipment .
26. A user equipment comprising an apparatus as claimed in any of claims to 14 to 24.
27. A base station comprising an apparatus as claimed in claim 25.
2
PCT/CN2012/079622 2012-08-03 2012-08-03 Method and apparatus WO2014019212A1 (en)

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CN102480756A (en) * 2010-11-29 2012-05-30 中兴通讯股份有限公司 Method and system for configuring multipoint coordinate transmission
CN102594528A (en) * 2011-01-10 2012-07-18 夏普株式会社 Trigger method for non-periodic channel state information feedback
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