WO2014077742A1 - Procédés et appareil pour la configuration de mappage d'antenne de signal de référence - Google Patents

Procédés et appareil pour la configuration de mappage d'antenne de signal de référence Download PDF

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Publication number
WO2014077742A1
WO2014077742A1 PCT/SE2012/051244 SE2012051244W WO2014077742A1 WO 2014077742 A1 WO2014077742 A1 WO 2014077742A1 SE 2012051244 W SE2012051244 W SE 2012051244W WO 2014077742 A1 WO2014077742 A1 WO 2014077742A1
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Prior art keywords
reference signals
configuration
transmitted
wireless device
antenna ports
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PCT/SE2012/051244
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English (en)
Inventor
Stefano Sorrentino
Robert Baldemair
Sara SANDBERG
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Telefonaktiebolaget L M Ericsson (Publ)
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Priority to PCT/SE2012/051244 priority Critical patent/WO2014077742A1/fr
Publication of WO2014077742A1 publication Critical patent/WO2014077742A1/fr

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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
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0026—Division using four or more dimensions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H04L27/261—Details of reference signals
    • H04L27/2613—Structure of the reference signals
    • 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
    • H04L5/0051—Allocation of pilot signals, i.e. of signals known to the receiver of dedicated pilots, i.e. pilots destined for a single user or terminal
    • 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
    • H04L5/0094—Indication of how sub-channels of the path are allocated
    • 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

Definitions

  • the disclosure relates to configuration of reference signals for transmission on multiple transmit antenna ports of a wireless device, and more specifically to mapping of reference signals to the multiple transmit antenna ports.
  • 3GPP Long Term Evolution is the fourth-generation mobile communication technologies standard developed within the 3 rd Generation Partnership Project (3GPP) to improve the Universal Mobile Telecommunication System (UMTS) standard to cope with future requirements in terms of improved services such as higher data rates, improved efficiency, and lowered costs.
  • the Universal Terrestrial Radio Access Network (UTRAN) is the radio access network of a UMTS and Evolved UTRAN (E-UTRAN) is the radio access network of an LTE system.
  • a wireless device such as a User Equipment (UE) is wirelessly connected to a Radio Base Station (RBS) commonly referred to as an evolved NodeB (eNodeB) in LTE.
  • RBS Radio Base Station
  • eNodeB evolved NodeB
  • An RBS is a general term for a radio network node capable of transmitting radio signals to a UE and receiving signals transmitted by a UE.
  • the eNodeB is a logical node in LTE and the RBS is a typical example of a physical implementation of an eNodeB.
  • Figure 1 illustrates a conventional radio access network in an LTE system.
  • An eNodeB 101 a with a transmission point 102a serves a UE 103 located within the eNodeB's geographical area of service also called a cell 105a.
  • the eNodeB 101 a is directly connected to the core network (not illustrated).
  • the eNodeB 101 a is also connected via an X2 interface to a neighboring eNodeB 101 b with a transmission point 102b serving another cell 105b.
  • CRS Cell-specific Reference Signals
  • the CRS are generally intended for use by all the UEs in the coverage area.
  • specific reference signals are provided for measuring the channel for the purpose of generating Channel State Information (CSI) feedback from the UE.
  • CSI-RS CSI Reference Signals
  • CSI-RS are not transmitted in every subframe, and they are generally sparser in time and frequency than reference signals used for demodulation.
  • CSI-RS transmissions may take place every fifth, tenth, twentieth, fortieth, or eightieth subframe, as determined by a periodicity parameter and a subframe offset, each of which are configured by Radio Resource Control (RRC) signaling.
  • RRC Radio Resource Control
  • a UE operating in connected mode can be requested by the base station to perform CSI reporting.
  • This reporting can include, for example, reporting a suitable Rank Indicator (Rl) and one or more Precoding Matrix Indices (PMI), given the observed channel conditions, as well as a Channel Quality Indicator (CQI).
  • Rl Rank Indicator
  • PMI Precoding Matrix Indices
  • CQI Channel Quality Indicator
  • Other types of CSI are also conceivable, including explicit channel feedback and interference covariance feedback.
  • the CSI feedback assists the RBS in scheduling, including deciding which subframe and resource blocks to use for the transmission, as well as deciding which transmission scheme and/or precoder to use.
  • the CSI feedback also provides information that can be used to determine a proper user bit-rate for the transmission, i.e., for Link Adaptation (LA).
  • LA Link Adaptation
  • a UE needs to continuously search for, synchronize to, and estimate the reception quality of both its serving cell and neighbor cells.
  • the reception quality of the neighbor cells in relation to the reception quality of the current serving cell, is then evaluated in order to determine whether a handover, for UEs in connected mode, or cell re-selection, for UEs in idle mode, should be carried out.
  • the handover decision is taken by the network, based on measurement reports provided by the UEs. Examples of such reports are Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) reports.
  • RSRP Reference Signal Received Power
  • RSRQ Reference Signal Receive
  • a point 210a-c corresponds to a set of antennas covering essentially a same geographical area 21 1 a-c in a similar manner as illustrated in Figure 2.
  • One transmitting and receiving node such as an LTE RBS, may control one or several points.
  • a point may correspond to one of the sectors at an RBS site, but it may also correspond to a site having one or more antennas all intending to cover a similar geographical area.
  • different points represent different sites.
  • Different antennas correspond to different points when they are sufficiently geographically separated and/or have antenna diagrams pointing in sufficiently different directions.
  • Techniques for CoMP entail introducing dependencies in the scheduling or transmission/reception among different points, in contrast to conventional cellular systems where a point is operated more or less independently from the other points, from a scheduling point of view.
  • the network When downlink CoMP is applied, the network needs to dynamically or semi- statically determine which transmission points are to serve each UE in the downlink. Additionally, the network needs to determine a set of points for which receiving feedback from the UE would be beneficial. Such a set of points for feedback reception is typically selected in a semi-static fashion, i.e., they are typically constant for several subframes. The corresponding feedback may be employed for scheduling, link adaptation and dynamic selection of the transmission points within the set of points for which feedback is available.
  • the set of suitable transmission points for a UE typically changes dynamically, e.g. as the UE moves through the network. The network therefore needs to select, and continuously update, a set of candidate transmission points for the UE. The UE then sends more detailed feedback, e.g. precoding information, for the points in the candidate set, thereby enabling the network to select the best downlink transmission points.
  • point selection The techniques mentioned above will be collectively referred to as "point selection" in the following.
  • the points in the candidate set may be determined in a UE-centric manner, wherein the UE performs measurements on downlink signals, such as CSI-RS, and reports the results to the network.
  • a network-centric approach may be used for point selection, wherein the network performs measurements such as pathloss measurements on uplink signals transmitted by the UE.
  • uplink Sounding Reference Signals SRS are generated using a base sequence. Each SRS is characterized by a sequence-group and a sequence-index, which define the base sequence. Base sequences are typically cell-specific and are a function of the cell-ID. Different base sequences are semi-orthogonal.
  • a phase shift may be applied in frequency domain sometimes also called a Cyclic Shift (CS) as the phase shift in the frequency domain correspond to a cyclic shift in the time domain, and an Orthogonal Cover Code (OCC) may be applied in time domain over the slots.
  • CS Cyclic Shift
  • OCC Orthogonal Cover Code
  • Zadoff-Chu sequences have the advantage that they exhibit constant power in time and frequency, which is desirable as it provides SRS sequences with small power variations in time and frequency, resulting in high power amplifier efficiency and comparable channel estimation quality for all frequency components.
  • j is the imaginary unit sqrt(-1 ), is the root sequence index, and 0 ⁇ « ⁇ N-1 yh e sequence-group and/or the sequence-index define the root sequence index U .
  • M is an integer
  • j is the imaginary unit sqrt(-1 )
  • k and I are integer numbers
  • v is the root sequence index.
  • the sequence-group and/or the sequence-index define the root sequence index v.
  • SRS are transmitted on the uplink to allow for the RBS to estimate the uplink channel state at different frequencies and time instances as compared to Physical Uplink Shared Channel (PUSCH) transmissions.
  • the channel state estimates can then, for example, be used by the network scheduler to assign resource blocks of instantaneously good quality for PUSCH transmission, also referred to as uplink channel-dependent scheduling.
  • Another alternative is to use the channel state estimates to select different transmission parameters such as the instantaneous data rate and different parameters related to uplink multi-antenna transmission.
  • SRS transmission can also be used for uplink timing estimation, as well as for estimating downlink channel conditions assuming downlink/uplink channel reciprocity.
  • an SRS is not necessarily transmitted together with any physical channel and if transmitted together with, for example, PUSCH, the SRS may cover a different, typically larger, frequency span. It may also be possible to employ SRS for mobility measurements, e.g. for cell and transmission/reception points association. SRS may also be used for uplink received signal strength measurements, which may e.g. be employed for adjusting the power transmitted by the corresponding UE.
  • SRS transmission There are two types of SRS transmission defined for LTE uplink: periodic SRS transmission, which has been available from the first release of LTE (release 8); and aperiodic SRS transmission, introduced in LTE release 10.
  • Periodic SRS transmission also known as Type 0 SRS, from a UE occurs at regular time intervals, from as often as once every 2 ms, i.e. every second subframe, to as infrequently as once every 160 ms, i.e. every 16th frame.
  • SRS is transmitted in a subframe, it occupies the last symbol of the subframe.
  • SRS can also be transmitted within the Uplink Pilot Time Slot (UpPTS).
  • UpPTS Uplink Pilot Time Slot
  • SRS transmissions should cover the frequency band that is of interest for the scheduler. This can be achieved in two ways:
  • the reference-signal sequence to use for SRS transmission within a cell is taken from the same sequence group as the demodulation reference signals used for channel estimation for Physical Uplink Control Channels (PUCCH). Similar to demodulation reference signals different phase rotations, typically referred to as cyclic shifts, can be used to generate different SRS that are orthogonal to each other. By assigning different phase rotations or cyclic shifts to different UEs, multiple SRS can thus be transmitted in parallel in the same subframe. However, it is then required that the SRSs all span the same frequency band. Another way to allow for SRS to be simultaneously transmitted from different terminals is to rely on the fact that each SRS only occupies every second subcarrier.
  • SRS transmissions from two UEs can be frequency multiplexed by assigning them to different frequency shifts or combs.
  • frequency multiplexing of SRS transmissions does not require the transmissions to cover identical frequency bands and is also less sensitive to differences in received signal strength.
  • the following set of parameters defines the characteristics of an SRS transmission: ⁇ SRS transmission bandwidth - that is, the bandwidth covered by a single SRS transmission.
  • Hopping bandwidth - that is, the frequency band over which the SRS transmission is frequency hopping.
  • Frequency-domain position - that is, the starting point of the SRS transmission in the frequency domain.
  • Transmission comb - that is, transmission on every n:th subcarrier.
  • the transmission comb may be defined as an odd or an even transmission comb.
  • SRS sequence A UE that is to transmit SRS is configured with these parameters by means of higher layer Radio Resource Control (RRC) signaling.
  • RRC Radio Resource Control
  • all UEs within a cell should be informed in what subframes SRS may be transmitted within the cell. This is to assure that the SRS symbol should not be used for PUSCH transmission within these subframes by any UE.
  • aperiodic SRS In contrast to periodic SRS, aperiodic SRS, also known as Type 1 SRS, are one- shot transmissions triggered by signaling on Physical Downlink Control Channel (PDCCH) as part of the scheduling grant or scheduling assignment.
  • PDCCH Physical Downlink Control Channel
  • the frequency-domain structure of an aperiodic SRS transmission is identical to that of periodic SRS.
  • aperiodic SRS are transmitted within the last symbol of a subframe.
  • the time instants when aperiodic SRS may be transmitted are configured per UE using higher-layer signaling.
  • the frequency-domain parameters for aperiodic SRS such as the bandwidth, and the transmission comb, are configured by higher-layer RRC signaling.
  • Multi-antenna mapping In case the UE is provided with multiple transmit antennas to be used e.g. for Multiple Input Multiple Output (MIMO), the LTE specifications enable functionalities for transmitting SRS on only one antenna port or for transmitting SRS on all the transmit antenna ports. Sounding of a single transmit antenna or antenna port is useful in case the UE is not exploiting its MIMO capabilities, e.g., for uplink transmission mode 1 , while sounding of the multiple antenna ports is necessary to enable uplink spatial link adaptation, e.g., for transmission mode 2.
  • the uplink transmission modes are specified in 3GPP TS 36.213 V1 1 .0.0 (2012- 09) section 8.0. If MIMO sounding is enabled, each transmit antenna port is assigned to a different cyclic shift. Additionally, different antenna ports for the same UE may be assigned to the same comb or to different combs, in order to enhance orthogonality among antenna ports as compared to orthogonality based on cyclic shift only.
  • RSRP is a function of the transmit power and average attenuation for a link, and not a function of the index of the transmit or receive antenna port over a link.
  • RSRP measurements may be challenging in certain scenarios, especially at low signal to noise ratios.
  • the current reference signal definition for SRS is based on the assumption that independent estimates are performed for each transmit antenna port.
  • a better RSRP estimation may be achieved by estimating a common RSRP value for all transmit antenna ports in a single estimation step.
  • RSRP are average measurements based on long term channel properties and an average transmitted power. Therefore, estimating RSRP based on one of the antennas may give unnecessarily biased estimates if it is assumed that the channel realizations for the transmit antennas are independent or at least not fully correlated, and that there are inaccuracies in the output power of the amplifiers.
  • a method for transmitting reference signals on multiple transmit antenna ports of a wireless device is provided.
  • the method is performed in the wireless device of a wireless communication system.
  • the method comprises receiving, from a radio network node, a configuration for transmission of reference signals.
  • the configuration defines a mapping of a reference signal to each of the multiple transmit antenna ports.
  • the reference signals are generated from a respective different base sequence.
  • the method also comprises transmitting the reference signals on the multiple transmit antenna ports in accordance with the received configuration.
  • a method for configuring reference signals for transmission on multiple transmit antenna ports of a wireless device is provided.
  • the method is performed in a radio network node of a wireless communication system.
  • the method comprises determining a configuration for transmission of reference signals by the wireless device.
  • the configuration defines a mapping of a reference signal to each of the multiple transmit antenna ports.
  • the reference signals are generated from a respective different base sequence.
  • the method also comprises sending the determined configuration to the wireless device, for configuring the wireless device to transmit the reference signals on the multiple transmit antenna ports in accordance with the determined configuration.
  • a wireless device of a wireless communication system is provided.
  • the wireless device is adapted to transmit reference signals on multiple transmit antenna ports.
  • the wireless device comprises a receiver adapted to receive, from a radio network node, a configuration for transmission of reference signals.
  • the configuration defines a mapping of a reference signal to each of the multiple transmit antenna ports.
  • the reference signals are generated from a respective different base sequence.
  • the wireless device also comprises a transmitter adapted to transmit the reference signals on the multiple transmit antenna ports in accordance with the received configuration.
  • a radio network node of a wireless communication system is provided.
  • the radio network node is adapted to configure reference signals for transmission on multiple transmit antenna ports of a wireless device.
  • the radio network node comprises a processing circuit adapted to determine a configuration for transmission of reference signals by the wireless device.
  • the configuration defines a mapping of a reference signal to each of the multiple transmit antenna ports.
  • the reference signals are generated from a respective different base sequence.
  • the radio network node further comprises a communication unit adapted to send the determined configuration to the wireless device, for configuring the wireless device to transmit the reference signals on the multiple transmit antenna ports in accordance with the determined configuration.
  • An advantage of embodiments is that improved RSRP estimations are enabled as compared to uplink measurements based on legacy SRS and SRS antenna port mapping, as the measurements of the reference signals transmitted on the multiple antenna ports may be combined to one higher quality RSRP measurement for a UE.
  • a further advantage of embodiments is that the estimation complexity is reduced, as an averaged RSRP measurement value over the multiple transmit antenna ports may be estimated in a single estimation step.
  • Figure 1 is a schematic illustration of a radio access network in LTE.
  • Figure 2 is a schematic illustration of a CoMP radio access network.
  • Figure 3 is a flowchart illustrating the method in the radio network node according to embodiments.
  • Figure 4 is a flowchart illustrating the method in the wireless device according to embodiments.
  • Figure 5 is a block diagram schematically illustrating the wireless device and the radio network node according to embodiments.
  • Embodiments are hereinafter described in a non-limiting general context in relation to an example scenario in E-UTRAN, where RSRP is measured by the network based on Reference Signals (RSs) transmitted by a wireless device on multiple antenna ports.
  • RSs Reference Signals
  • the embodiments may be applied to any radio access network technology supporting measurements based on RSs.
  • the RSRP measurement is only one example of a measurement that may benefit of RSs mapped to the multiple antenna ports according to embodiments of the invention.
  • Other example measurements are RSRQ, i.e. , measurements of channel quality taking the interference into account.
  • the wireless device may be any kind of wireless terminal with multiple antenna ports, such as a UE, a portable computer, or a smartphone.
  • the wireless device will be exemplified by a MIMO UE.
  • the mapping of uplink RSs to the antenna ports of a MIMO UE may be performed in several ways. Some conventional examples comprise transmitting RSs only from a single antenna port or transmitting orthogonal RS sequences from all the different antenna ports. In the case of SRS transmissions in LTE, the SRSs from the different antenna ports are made orthogonal by assigning different cyclic shifts or a combination of cyclic shifts and Orthogonal Cover Codes (OCC) to a same base sequence to each port.
  • OCC Orthogonal Cover Codes
  • cyclic shifts are not provided for some RSs.
  • a RS which may not use cyclic shifts is a RS type similar to SRS, but with some important differences that make it possible to successfully receive and measure the RS at several different points, such as in a CoMP network deployment.
  • Such a large comb factor enables frequency division multiplexing of many UEs.
  • a large frequency span is provided, which enables frequency-domain averaging of the received power. Cyclic shift multiplexing of UEs is not provided.
  • each UE transmits the RSRP-RS only on a few subcarriers, which means that the maximum transmit power per subcarrier is relatively high.
  • This enables RSRP measurements of the RSRP-RS also at points that are farther away.
  • the power control of the RSRP-RS may be adjusted to make sure that the signal may be received at all desired points.
  • RSRP measurements may be challenging at low signal to noise ratios.
  • the current RS definition for SRS is based on the assumption that independent estimates are performed per each transmit antenna port.
  • a better RSRP estimation and reduced estimation complexity may be achieved by estimating a common RSRP value for multiple transmit antenna ports in a single estimation step.
  • RSRP is typically assumed to be constant for all transmission ports.
  • RSRP estimations may be affected by instantaneous fading conditions. Therefore it may be beneficial to combine measurements based on different fading realizations.
  • uplink RSRP coverage resolution may be limited by the transmission power of the UE. Depending on the UE implementation, it is possible that the UE is able to produce a maximum transmission power only when multiple transmission ports and thus PAs are transmitting simultaneously.
  • each antenna port individually on orthogonal RS resources is thus a waste of RS capacity in the case of RSRP measurements, as the RSs do not need to and should preferably not be measured individually. Therefore, antenna mapping configurations for sounding RSs that are optimized for RSRP measurements are needed. Examples of situations when the methods according to embodiments of the invention are especially useful comprise the situation when RSs are used for RSRP measurements and the situation when orthogonality of the RSs through cyclic shifts is not possible to achieve, as e.g. for RSRP-RS described previously.
  • each RS is generated from a base sequence which is different from any of the other RSs' base sequences.
  • different Zadoff-Chu sequences may be used.
  • the RSs need not be orthogonal, they may be generated using different base sequences instead of using a same base sequence with different cyclic shifts as for SRS. RSs generated using different base sequences will provide quasi-orthogonal RSs.
  • a radio network node such as an eNodeB may thus determine the configuration to use for the antenna mapping of RSs, and send the configuration to the MIMO UE.
  • the MIMO UE receives the configuration and applies the configuration when transmitting the RSs on its multiple antenna ports.
  • the new mapping configurations allow for improved RSRP measurements based on the RSs.
  • a MIMO UE is configured to transmit from multiple transmit antenna ports on a same set of subcarriers, e.g. on a same comb.
  • the signal associated to each antenna port is characterized by a different RS in terms of a different scrambling sequence.
  • Such a scrambling sequence correspond to a base sequence used e.g. for generating SRSs.
  • a Zadoff-Chu sequence is characterized by a specific base sequence index.
  • the receiver at the receiving point e.g. at one of several coordinated multi-points, sees a composite channel given by the superposition of the channels and the different base sequences.
  • An estimation of the RSRP based on a measurement of the RS is therefore less subject to bias introduced by coherent combination of the channels for the different antenna ports. This is due to that the combining weights for the antenna ports are independently scrambled for each used subcarrier.
  • the transmission power may be split among the transmission antenna ports and the corresponding PAs, easing the transmission power requirements of each PA.
  • RSRP is almost constant for all transmission ports but the measurements may be affected by instantaneous fading conditions.
  • a further advantage of embodiments of the invention is that the received signal results of the combination of different antennas, which may each be associated with a different instantaneous fading realization. The receiver is thus able to estimate a better average of the signals. Consequently, the RSRP measurement for a MIMO UE will give a higher quality measurement when using the suggested antenna mapping configurations compared to using conventional SRS antenna mapping.
  • the MIMO UE may transmit the RSs from the different transmit antenna ports on different sets of subcarriers, e.g. on different combs. This is an advantageous alternative for UEs using RS with a short sequence length, as it allows improving the inter-antenna interference suppression.
  • a combination of using a same set of subcarriers and different sets of subcarriers for the transmission on the different antenna ports is used.
  • the interference suppression gain is low for a short sequence length, thus making it advantageous to assign different sets of subcarriers to different antenna ports such that the inter-antenna interference is reduced.
  • UEs with a longer sequence length may be configured to use a same set of subcarriers for multiple antenna ports. In this way the multiplexing capacity is maximized while still achieving sufficient interference suppression.
  • UEs using a wide enough RS with regards to bandwidth which implies a long enough sequence may be configured to transmit on a same comb and with different RS base sequences on its transmit antenna ports, whereas UEs with an insufficient RS sequence length transmit on different combs and with different RS base sequences.
  • the criterion for deciding whether to configure the UE to use a same comb or different combs is thus the sequence length of the RS.
  • the sequence is probably long enough and the same comb may be used on multiple antenna ports.
  • the network may thus make the best choice between using different combs or a same comb for a UE, based on the sequence length. Thereby all UEs may transmit close to orthogonal reference signals from each antenna port without adding severe overhead or being limited by the RS multiplexing capacity.
  • One aspect common to all embodiments of the invention is that the specific mapping of sounding RS to antennas, or equivalently to antenna ports, is a function of the purpose of the RS.
  • FIG. 3 is a flowchart illustrating a method for configuring RSs for transmission on multiple transmit antenna ports of a wireless device.
  • the method is performed in a radio network node of a wireless communication system.
  • the radio network node may e.g. be an eNodeB.
  • the method comprises:
  • the configuration defines a mapping of a RS to each of the multiple transmit antenna ports.
  • the RSs are generated from a respective different base sequence.
  • the configuration may also define that the RSs are transmitted on a transmission comb.
  • the configuration may define that the RSs are all transmitted on a same set of subcarriers. If the RSs are transmitted on a transmission comb, they will thus be transmitted on the same transmission comb on multiple antenna ports of the wireless device. This would be a good alternative when the RS sequence length is long enough, e.g. for a transmission comb factor of two where the RSs are transmitted on every second subcarrier.
  • the configuration may define that the RSs are transmitted on a respective different set of subcarriers. If the RSs are transmitted on a transmission comb, they will thus be transmitted on different transmission combs on the multiple antenna ports. Transmitting on different transmission combs on the antenna ports would be a good alternative for UEs using RS with a short sequence length, as it allows improving the inter-antenna interference suppression.
  • a combination of the first and the second embodiment is used, and the configuration defines:
  • a same base sequence is used when generating the RSs for the multiple antenna ports of a UE, and the UE is configured to transmit the RSs on a respective different set of subcarriers on the different antenna ports, typically on different transmission combs. No cyclic shift of the base sequence is needed as full orthogonality is obtained between the different combs.
  • the method further comprises:
  • the measurement may be a received power measurement, e.g. an RSRP measurement.
  • the result is retrieved from at least one receiving point of the radio network node. If the method is performed in en eNodeB of a CoMP network with more than one receiving point, the RSRP may be retireved from a number of receiving points. As the RSRP measurements are done on RSs transmitted by the wireless device in accordance with the determined configuration of embodiments of the invention, the RSRP measurements may be of higher quality than if they were done on conventional SRS, as described above.
  • Figure 4 is a flowchart illustrating a method for transmitting RSs on multiple transmit antenna ports of a wireless device.
  • the method is performed in the wireless device of a wireless communication system.
  • the wireless device may e.g. be a MIMO UE.
  • the method comprises:
  • - 410 Receiving, from a radio network node, a configuration for transmission of RSs.
  • the configuration defines a mapping of a RS to each of the multiple transmit antenna ports.
  • the RSs are generated from a respective different base sequence.
  • the configuration may also define that the RSs are transmitted on a transmission comb.
  • the configuration may define that the RSs are all transmitted on a same set of subcarriers. If the RSs are transmitted on a transmission comb, they will thus be transmitted on the same transmission comb on multiple antenna ports. This would be a good alternative when the RS sequence length is long enough, e.g. for a transmission comb factor of two where the RSs are transmitted on every second subcarrier.
  • the configuration may define that the RSs are transmitted on a respective different set of subcarriers. If the RSs are transmitted on a transmission comb, they will thus be transmitted on different transmission combs on the multiple antenna ports. Transmitting on different transmission combs on the antenna ports would be a good alternative for UEs using RS with a short sequence length, as it allows improving the inter-antenna interference suppression.
  • a wireless device 500 and a radio network node 550 of a wireless communication system are schematically illustrated in the block diagram in Figure 5.
  • the radio network node 550 is adapted to configure RSs for transmission on multiple transmit antenna ports of the wireless device.
  • the antenna ports are connected to their respective antennas, 508a and 508b.
  • the radio network node comprises a processing circuit 551 adapted to determine a configuration for transmission of RSs by the wireless device.
  • the configuration defines a mapping of a RS to each of the multiple transmit antenna ports.
  • the RSs are generated from a respective different base sequence.
  • the radio network node also comprises a communication unit 552 adapted to send the determined configuration to the wireless device, for configuring the wireless device to transmit the RSs on the multiple transmit antenna ports in accordance with the determined configuration.
  • the communication unit may e.g. be the transmitter of an eNodeB.
  • the processing circuit 551 may be adapted to determine the configuration, defining also that the RSs are transmitted on a
  • the processing circuit 551 may be adapted to determine the configuration, defining that the RSs are all transmitted on a same set of subcarriers. In accordance with the second embodiment described above, the processing circuit 551 may be adapted to determine the configuration, defining that the RSs are transmitted on a respective different set of subcarriers.
  • the processing circuit 5 551 may be adapted to determine the configuration defining: that the RSs are all transmitted on a same set of subcarriers if a sequence length of the RSs exceeds a threshold, and that the RSs are transmitted on a respective different set of subcarriers otherwise.
  • the processing unit 551 may be further adapted to retrieve a result from a measurement of the RSs transmitted by the wireless device on the multiple transmit antenna ports.
  • the measurement may be a received power measurement such as an RSRP measurement.
  • the result may be retrieved from at least one receiving point 555a, 555b, of the radio network node.
  • the wireless device 500 is adapted to transmit RSs on multiple transmit antenna ports.
  • the wireless device comprises a receiver 501 adapted to receive, from a radio network node, a configuration for transmission of RSs.
  • the configuration defines a mapping of a RS to each of the multiple transmit antenna ports.
  • the RSs are generated from a respective different base sequence.
  • the wireless device0 also comprises a transmitter 502 adapted to transmit the RSs on the multiple transmit antenna ports in accordance with the received configuration.
  • the wireless device comprises a processing circuit 503 for the processing needed in relation to the RS transmission.
  • the receiver 501 may be adapted to receive the5 configuration defining that the RSs are transmitted on a transmission comb.
  • the receiver 501 may be adapted to receive the configuration defining that the RSs are all transmitted on a same set of subcarriers.
  • the receiver 501 may be adapted to receive the configuration defining that the RSs are transmitted on a respective different set of subcarriers.
  • the radio network node 550 comprises a Central Processing Unit (CPU) which may be a single unit or a plurality of units. Furthermore, the radio network node 550 comprises at least one computer program product (CPP) in the form of a non-volatile memory, e.g. an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory or a disk drive.
  • the CPP comprises a computer program, which in turn comprises code means which when run on the radio network node 550 causes the CPU to perform steps of the procedure described earlier in conjunction with Figure 3. In other words, when said code means are run on the CPU, they correspond to the processing circuit 551 in the radio network node 550 of Figure 5

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

Abstract

L'invention concerne un procédé de configuration de signaux de référence pour la transmission sur de multiples ports d'antenne de transmission d'un dispositif sans fil. Le procédé est réalisé dans un nœud de réseau radio d'un système de communication sans fil. Le procédé comprend la détermination (410) d'une configuration par la transmission de signaux de référence par le dispositif sans fil. La configuration définit un mappage d'un signal de référence à chacun des multiples ports d'antenne de transmission. Les signaux de référence sont générés à partir d'une séquence de base différente respective. Le procédé comprend également l'envoi (420) de la configuration déterminée au dispositif sans fil, afin de configurer le dispositif sans fil pour transmettre les signaux de référence sur les multiples ports d'antenne de transmission en conformité avec la configuration déterminée.
PCT/SE2012/051244 2012-11-13 2012-11-13 Procédés et appareil pour la configuration de mappage d'antenne de signal de référence WO2014077742A1 (fr)

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EP3240343A4 (fr) * 2014-12-25 2017-12-27 ZTE Corporation Procédé et dispositif de configuration de signal d'acquisition de canal et de génération de signal d'acquisition de canal
US10171217B2 (en) * 2015-01-16 2019-01-01 RF DSP Inc. Enhanced SRS for massive MIMO channel estimation
US20180026765A1 (en) * 2015-01-16 2018-01-25 RF DSP Inc. Enhanced srs for massive mimo channel estimation
WO2016115548A1 (fr) * 2015-01-16 2016-07-21 Ping Liang Signal de référence de sondage (srs) amélioré pour une estimation de canal mimo massif
WO2017190361A1 (fr) * 2016-05-06 2017-11-09 华为技术有限公司 Procédé et dispositif d'émission de signal de référence
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CN109075931B (zh) * 2016-05-06 2020-11-17 华为技术有限公司 一种参考信号传输方法及装置
CN109075931A (zh) * 2016-05-06 2018-12-21 华为技术有限公司 一种参考信号传输方法及装置
WO2018027886A1 (fr) * 2016-08-12 2018-02-15 Telefonaktiebolaget Lm Ericsson (Publ) Configuration de signal de référence de mobilité à deux niveaux
US12035165B2 (en) 2016-08-12 2024-07-09 Telefonaktiebolaget Lm Ericsson (Publ) Two-level mobility reference signal configuration
US10244419B2 (en) 2016-08-12 2019-03-26 Telefonaktiebolaget Lm Ericsson (Publ) Two-level mobility reference signal configuration
US11202219B2 (en) 2016-08-12 2021-12-14 Telefonaktiebolaget Lm Ericsson (Publ) Two-level mobility reference signal configuration
US10638350B2 (en) 2016-08-12 2020-04-28 Telefonaktiebolaget Lm Ericsson (Publ) Two-level mobility reference signal configuration
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CN110168954B (zh) * 2017-01-09 2022-08-16 高通股份有限公司 在新无线电中发送经复用的探测参考信号端口
EP3566334A4 (fr) * 2017-01-09 2020-07-29 QUALCOMM Incorporated Transmission de ports de signal de référence de sondage multiplexés dans une nouvelle radio
WO2018127171A1 (fr) 2017-01-09 2018-07-12 Qualcomm Incorporated Transmission de ports de signal de référence de sondage multiplexés dans une nouvelle radio
WO2018140321A1 (fr) * 2017-01-26 2018-08-02 Qualcomm Incorporated Signaux de référence flexibles basés sur des peignes
US10498506B2 (en) 2017-01-26 2019-12-03 Qualcomm Incorporated Flexible comb-based reference signals
US10862636B2 (en) 2017-08-25 2020-12-08 Telefonaktiebolaget Lm Ericsson (Publ) Configuration of physical antenna ports
CN111052618A (zh) * 2017-08-25 2020-04-21 瑞典爱立信有限公司 物理天线端口的配置
US10348462B2 (en) 2017-08-25 2019-07-09 Telefonaktiebolaget Lm Ericsson (Publ) Configuration of physical antenna ports
WO2019037865A1 (fr) * 2017-08-25 2019-02-28 Telefonaktiebolaget Lm Ericsson (Publ) Configuration de ports d'antenne physique
CN113348634A (zh) * 2019-01-28 2021-09-03 索尼集团公司 多天线面板上行链路通信
CN113348634B (zh) * 2019-01-28 2024-05-28 索尼集团公司 多天线面板上行链路通信
US12040870B2 (en) 2019-01-28 2024-07-16 Sony Group Corporation Multiple antenna panel uplink communication

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