EP2446688A1 - Signaling femto-cell deployment attributes to assist interference mitigation in heterogeneous networks - Google Patents

Signaling femto-cell deployment attributes to assist interference mitigation in heterogeneous networks

Info

Publication number
EP2446688A1
EP2446688A1 EP10725557A EP10725557A EP2446688A1 EP 2446688 A1 EP2446688 A1 EP 2446688A1 EP 10725557 A EP10725557 A EP 10725557A EP 10725557 A EP10725557 A EP 10725557A EP 2446688 A1 EP2446688 A1 EP 2446688A1
Authority
EP
European Patent Office
Prior art keywords
base station
neighbor base
bandwidth
henb
downlink
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP10725557A
Other languages
English (en)
French (fr)
Inventor
Sandeep H. Krishnamurthy
Michae L E. Buckley
Murali Narasimha
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Google Technology Holdings LLC
Original Assignee
Motorola Mobility LLC
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 Motorola Mobility LLC filed Critical Motorola Mobility LLC
Publication of EP2446688A1 publication Critical patent/EP2446688A1/de
Withdrawn legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W72/00Local resource management
    • H04W72/50Allocation or scheduling criteria for wireless resources
    • H04W72/54Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/541Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W72/00Local resource management
    • H04W72/20Control channels or signalling for resource management
    • H04W72/21Control channels or signalling for resource management in the uplink direction of a wireless link, i.e. towards the network
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W84/00Network topologies
    • H04W84/02Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04Large scale networks; Deep hierarchical networks
    • H04W84/042Public Land Mobile systems, e.g. cellular systems
    • H04W84/045Public Land Mobile systems, e.g. cellular systems using private Base Stations, e.g. femto Base Stations, home Node B

Definitions

  • the present disclosure relates to spectral efficiency optimization via interference control and mitigation in heterogeneous networks comprising macro-cells and home-base stations or femto-cells.
  • UMTS Universal Mobile Telecommunications System
  • 3 GPP Third Generation Partnership Project
  • 3GPP is a collaboration among groups of telecommunications associations to make a globally applicable third generation (3G) mobile phone system specification within the scope of the International Mobile Telecommunications-2000 project of the International Telecommunication Union (ITU).
  • the UMTS standard is evolving and is typically referred to as UMTS Long Term Evolution (LTE) or Evolved UMTS Terrestrial Radio Access (E-UTRA).
  • LTE UMTS Long Term Evolution
  • E-UTRA Evolved UMTS Terrestrial Radio Access
  • OFDM orthogonal frequency division multiplexing
  • eNB enhanced Node-B
  • UE wireless communication device
  • OFDM orthogonal frequency division multiplexing
  • orthogonal subcarriers are modulated with a digital stream, which may include data, control information, or other information, so as to form a set of OFDM symbols.
  • the subcarriers may be contiguous or non-contiguous and the downlink data modulation may be performed using quadrature phase shift-keying (QPSK), 16-ary quadrature amplitude modulation (16QAM), or 64QAM.
  • QPSK quadrature phase shift-keying
  • 16QAM 16-ary quadrature amplitude modulation
  • 64QAM 64QAM
  • the OFDM symbols are configured into a downlink sub frame for transmission from the base station.
  • Each OFDM symbol has a time duration and is associated with a cyclic prefix (CP).
  • CP cyclic prefix
  • a cyclic prefix is essentially a guard period between successive OFDM symbols in a sub frame.
  • a normal cyclic prefix is about five (5) microseconds and an extended cyclic prefix is about 16.67 microseconds.
  • the data from the serving base station is transmitted on physical downlink shared channel (PDSCH) and the control information is signaled on physical downlink control channel (PDCCH).
  • PDSCH physical downlink shared channel
  • PDCCH physical downlink control channel
  • uplink communications from the UE to the eNB utilize single-carrier frequency division multiple access (SC-FDMA) according to the E-UTRA standard.
  • SC-FDMA single-carrier frequency division multiple access
  • block transmission of QAM data symbols is performed by first discrete Fourier transform (DFT)-spreading (or precoding) followed by subcarrier mapping to a conventional OFDM modulator.
  • DFT precoding allows a moderate cubic metric / peak-to-average power ratio (PAPR) leading to reduced cost, size and power consumption of the UE power amplifier.
  • PAPR peak-to-average power ratio
  • each subcarrier used for uplink transmission includes information for all the transmitted modulated signals, with the input data stream being spread over them.
  • the data transmission in the uplink is controlled by the eNB, involving transmission of scheduling grants (and scheduling information) sent via downlink control channels.
  • Scheduling grants for uplink transmissions are provided by the eNB on the downlink and include, among other things, a resource allocation (e.g., a resource block size per one millisecond (ms) interval) and an identification of the modulation to be used for the uplink transmissions.
  • a resource allocation e.g., a resource block size per one millisecond (ms) interval
  • AMC adaptive modulation and coding
  • large spectral efficiency is possible by scheduling users with favorable channel conditions.
  • the UE transmits data on the physical uplink shared channel (PUSCH).
  • the physical control information is transmitted by the UE on the physical uplink control channel (PUCCH).
  • E-UTRA systems also facilitate the use of multiple input and multiple output (MIMO) antenna systems on the downlink to increase capacity.
  • MIMO antenna systems are employed at the eNB through use of multiple transmit antennas and at the UE through use of multiple receive antennas.
  • a UE may rely on a pilot or reference symbol (RS) sent from the eNB for channel estimation, subsequent data demodulation, and link quality measurement for reporting.
  • the link quality measurements for feedback may include such spatial parameters as rank indicator, or the number of data streams sent on the same resources; precoding matrix index (PMI); and coding parameters, such as a modulation and coding scheme (MCS) or a channel quality indicator (CQI).
  • MCS modulation and coding scheme
  • CQI channel quality indicator
  • HeNBs Home-eNBs
  • a HeNB can either belong to a closed subscriber group (CSG) or can be an open-access cell.
  • CSG is set of one or more cells that allows access only to certain group of subscribers.
  • HeNB deployments where at least a part of the deployed bandwidth (BW) is shared with macro-cells are considered to be high-risk scenarios from an interference point-of-view.
  • the uplink of the HeNB can be severely interfered with particularly when the HeNB is far away (for example > 400 m) from the macro-cell, thereby, degrading the quality of service of UEs connected to the HeNB.
  • the existing Rel-8 UE measurement framework can be made use of identify the situation when this interference might occur and the network can handover the UE to an inter-frequency carrier which is not shared between macro-cells and HeNBs to mitigate this problem.
  • being able to efficiently operate HeNBs on the entire available spectrum might be desirable from a cost perspective.
  • FIG. 1 shows a schematic diagram with macro-cell and a home-base station in the macro-cell's coverage area, in accordance with the present invention.
  • FIG. 2 shows a schematic diagram with macro-cell and a home-base station in the macro-cell's coverage area, in accordance with the present invention.
  • FIG. 3 illustrates a diagram showing the bandwidth arrangement in E-UTRA network (E-UTRAN) downlink.
  • FIG. 4 shows a diagram indicating the bandwidth arrangement on the uplink of a heterogeneous network, in accordance with the present invention.
  • FIG. 5 is a logic flow diagram of steps executed by a wireless communication device to process a downlink transmission from a neighbor base station and decode the transmission attributes of that base station and further signaling of the decoded attributes to the serving base station, in accordance with the present invention.
  • FIGs. 6 and 7 show flow diagrams of the steps executed by a base station making use of the reports containing bandwidth attributes corresponding to a neighbor base station in scheduling its users to mitigate the DL/UL interference problem, in accordance with the present invention.
  • the device is served by a serving base station and receives from a neighbor base station a downlink transmission including a broadcast signal.
  • the device decodes the broadcast signal, and determines a bandwidth attribute associated with the neighbor base station based on the broadcast signal.
  • the device then sends to the serving base station a report including the bandwidth attribute associated with the neighbor base station.
  • the wireless base station receives from a first wireless terminal a signal including a bandwidth attribute associated with a neighbor base station.
  • the base station then schedules a second wireless terminal based on the bandwidth attribute of the neighbor base station, in which the first wireless terminal may be identical to the second wireless terminal.
  • a heterogeneous network comprising macro cells and HeNBs cells that have overlapping bandwidth (BW) deployments
  • BW bandwidth
  • Fig. 1 One such interference problem is depicted in Fig. 1, where the uplink (UL) transmission from a UE connected to a macro-eNB (MeNB) that is close to (i.e., within signal range of a HeNB) severely interferes with the UL of a UE connected to the HeNB.
  • MeNB macro-eNB
  • This case has been identified as interference scenario 3 in 3GPP TR 25.967 "Home Node B Radio Frequency (RF) Requirements (FDD) (Release 9)" in Universal Terrestrial Radio Access (UTRA) network.
  • RF Radio Frequency
  • FDD Frequency Requirements
  • UTRA Universal Terrestrial Radio Access
  • UTRA-framework 3GPP TR 25.967 are likely to be investigated in the LTE context for mitigating this problem. However, this alone might not be sufficient in achieving the best spectral efficiency possible with heterogeneous deployments. In the sequel, we discuss some further methods that can be useful in making HeNB deployments more efficient.
  • a coarse geolocation of UEs is possible by thresholding either the pathloss (PL) of the UE from a HeNB or alternately, thresholding the differential pathloss between HeNB and MeNB.
  • PL pathloss
  • the UE is close HeNB.
  • the difference PL(MeNB to UE) - PL(HeNB to UE)
  • the UE is not only close to the HeNB, but it can pose a significant interference risk to the UL of the HeNB.
  • a macro-cell UE that is far away from the macro-cell but near a CSG cell transmits with large power, it can cause UL interference to CSG UEs.
  • the UE can read the system information broadcast (SIB) containing information element pertaining to the downlink transmit power of the HeNB. Alternately, it can make some assumptions on the downlink transmit power (eg. set it to maximum allowed power per the power class of HeNBs deployed in the network).
  • SIB system information broadcast
  • the UL bandwidth of a HeNB is not equal to the UL bandwidth of the macro-cells.
  • Fractional frequency reuse (which is being investigated) where a certain HeNB may use only a portion of the available bandwidth configured semi- statically or dynamically is enabled.
  • Fig. 3 shows a potential UL BW arrangement for two example cases.
  • the HeNB carrier on the UL is offset relative to the MeNB UL carrier.
  • the HeNB and MeNB share the same carrier.
  • the HeNB UL overlaps with only a part of the MeNB UL. This means that, if a MUE were to roam close to a HeNB, then the UL interference from MUE to HeNB can be mitigated by scheduling PUSCH RBs for the MUE outside of the bandwidth used in HeNB UL. This is feasible if the MeNB has information pertaining to
  • the UL BW configured by the HeNB.
  • the center frequency of the HeNB is offset by at least 6 PRBs from the macro-cell frequency layers, but with overlapping bandwidths as shown in Fig. 2.
  • the offset is enabled to avoid MeNB— HeNB interference on
  • SCH synchronization channel
  • MIB Master Information Block
  • the DL bandwidth of a HeNB is not equal to the DL bandwidth of the macro-cells.
  • Fractional frequency reuse (which is being investigated) where a certain HeNB may use only a portion of the available bandwidth configured semi-statically or dynamically is enabled.
  • the BWs supported by Rel-8 eNBs are typically from the set ⁇ 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 20 MHz ⁇ , while the BWs for CSG cells (HeNBs) will likely be from the set ⁇ 5 MHz, 10 MHz ⁇ .
  • HeNBs BWs for CSG cells
  • the BW of the deployed homogenous network is 10 MHz and there could be a number of 5 MHz or 10 MHz HeNBs sharing (at least a part of) the BW.
  • the HeNB carrier can be offset relative to the macro-cells and these offsets could be different for different HeNBs.
  • the network may have access to the raster of carriers on which HeNBs in an geographical location are situated on but the network (NW) operations and management (O&M) otherwise has limited knowledge of whether at a given point in time HeNBs are serving on a certain carrier frequency or not. This is because the HeNB deployments are intended to be uncoordinated. Further, it is possible that a HeNB powers up at some arbitrary instant in time without the MeNBs knowing about it for the same reason. Whether or not • a certain UE connected to a MeNB can be interfered on the DL by a HeNB, or
  • a certain UE can interfere with HeNB UL (victim) depends on the location of the UE in the macro-cell and its proximity to the HeNB.
  • the UE can be asked by the serving macro-cell to scan the raster on which HeNBs could be present and identify cells within its range to report some attributes associated with the HeNB back to the serving base station.
  • the reporting of the pair physical cell identifier (PCID) and the reference signal received power (RSRP) is defined to enable measurements-based mobility.
  • the UE needs to be able to detect the synchronization channel (SCH) and measure the power on the received cell-specific reference signal (CRS).
  • SCH synchronization channel
  • CRS cell-specific reference signal
  • the macro-cell that is serving the UE has knowledge of the transmission BW of the HeNB that the UE is close to both on the UL and DL, it can deduce the part of the BW it can use that is not occupied by any of the CSG cells in the range of a given UE. This frequency region can then be used for DL/UL scheduling of the UE by the macro-cell avoiding DL/UL interference from and to the CSG cell DL/UL respectively.
  • Asymmetric DL/UL deployments are likely (eg. 10 MHz DL and 5 MHz UL, etc.) in typical HeNB deployments. Also, it is possible that a single network has HeNBs with different BW capabilities.
  • Variable UL/DL separation is not only useful to deploy certain interference mitigation techniques (eg. DL carrier offset avoidance of
  • MeNB HeNB interference of SCH/MIB channels, frequency reuse, etc. but, might be necessary if carrier aggregation is enabled. Therefore, different UL/DL separations than that in Rel-8 are likely in the future. • The operator has knowledge of the E-UTRA Absolute Frequency
  • Fig. 5 shows a flow chart corresponding to an embodiment.
  • the UE can read the master information block (MIB) and/or system information broadcast (SIB) transmitted from the HeNBs, it can determine the DL BW of the HeNB, the UL carrier frequency information (in FDD systems, the DL and UL carrier are different) and the DL/UL carrier frequency separation (in TDD systems, the UL and DL carriers are the same - therefore, the DL/UL carrier separation is not defined). After determination of one or more of these quantities, the UE can report these transmission parameters
  • MIB master information block
  • SIB system information broadcast
  • the UE can process the basic information decoded from MIB and/or SIB and then signal functions derived from these quantities. For example, one or more of the quantities PCID, DL BW, UL BW, UL carrier frequency and DL/UL duplexer separation can be included in the report sent by the UE on the UL. Alternately, the common resource block (RB) space in frequency-domain used by one or more HeNBs within range can be determined and signaled.
  • RB common resource block
  • the report may include the pair (RB lower end index, RB upper end index) or alternately (RB lower end, number of RBs used on UL).
  • the RB indexing can be relative to the macro-cell RB numbering and this information can be signaled separately for both DL and UL.
  • the UE has the capability to perform the following actions in a FDD deployment.
  • UL carrier frequency for example, ul-CarrierFreq information element defined in TS 36.331
  • the UE has the capability to perform the following actions in a TDD deployment.
  • the UE can report the UL/DL/carrier attributes relating the UL/DL transmission in the HeNB to the serving MeNB on the UL.
  • the information may be transmitted in a radio resource control (RRC) report or some other uplink control signalling.
  • RRC radio resource control
  • the serving base station may configure a measurement gap to allow for the UE to tune its radio frequency (RF) oscillator to the relevant inter- frequency carrier.
  • RF radio frequency
  • the UE can additionally detect and report the frame timing difference between the MeNB and the HeNB.
  • the list of candidate carrier frequencies on which HeNBs are allowed to operate on within a given band are known to the network operator. There are many way such a list can be signalled.
  • the EARFCN of the raster frequencies can be signalled.
  • the range of EARFCN can be signalled.
  • the list can be signalled implicitly by indicating that the UE scan all of the raster frequencies (with 100 kHz separation in LTE) within the operating bandwidth of the MeNB.
  • Figs. 6 and 7 illustrate flow charts outlining steps that a MeNB may carry out making use of the information reported by the UE according to the embodiment.
  • the information reported in the embodiment relating to the UL/DL BW attributes of the HeNB can provide a MeNB with sufficient capability to mitigate both DL and UL problems in heterogeneous deployments.
  • the first method involves identification of the set of resources available DL scheduling on PDSCH of MeNB that overlaps with the HeNB DL.
  • the set of resources can be one or more RBs.
  • the MeNB can either not schedule any user on those resources to avoid interfering with the HeNB DL. Alternately, the MeNB can transmit on those resources at lower power than the maximum base station transmit power to reduce the interference it causes on the HeNB DL.
  • the second method also involves identification of resources available on the MeNB DL that overlap with HeNB transmission.
  • the MeNB uses spatial interference mitigation techniques (for example, beamforming with dedicated reference signal or DRS-based scheduling) to point the beam at the MUE being served thereby, avoiding interference to a UE connected to the HeNB.
  • the information reported in the embodiment relating to the UL BW/UL carrier attributes of the HeNB can provide a MeNB with sufficient capability to mitigate UL interference problems in heterogeneous deployments.
  • the MeNB can identify the set of resources available for scheduling users on the UL that do not overlap with the resources used by HeNB for its users on its UL.
  • the resources can correspond to resource blocks (RBs) available for transmission on the PUSCH.
  • the MeNB can allocate UL resources to a MUE such that the MUE avoids interfering with a nearby HeNB on its UL by scheduling on non- overlapping resources.
  • the additional UE reporting equips the marco-eNB with the necessary information to perform PUSCH scheduling that does not interfere with HeNB data and control on the uplink.
  • this approach can bring large gains to HeNB performance.

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  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
EP10725557A 2009-06-23 2010-05-27 Signaling femto-cell deployment attributes to assist interference mitigation in heterogeneous networks Withdrawn EP2446688A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US21965809P 2009-06-23 2009-06-23
PCT/US2010/036315 WO2011005373A1 (en) 2009-06-23 2010-05-27 Signaling femto-cell deployment attributes to assist interference mitigation in heterogeneous networks

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EP2446688A1 true EP2446688A1 (de) 2012-05-02

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FR2986158A1 (fr) 2012-01-31 2013-08-02 Sorin Crm Sas Dispositif medical implantable actif comprenant des moyens de diagnostic de l'insuffisance cardiaque
JP5974176B2 (ja) * 2012-08-10 2016-08-23 テレコム・イタリア・エッセ・ピー・アー ヘテロジニアス・モバイル・ネットワークにおけるアップリンク干渉の軽減
US10560304B2 (en) * 2017-07-12 2020-02-11 Qualcomm Incorporated Techniques and apparatuses for multiplexing schemes for millimeter wave downlink single carrier waveforms

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GB2404113B (en) * 2003-07-12 2005-11-02 * Motorola, Inc Communication units, cell-based communication system and method for frequency planning therein
EP1909523A1 (de) * 2006-10-02 2008-04-09 Matsushita Electric Industrial Co., Ltd. Verbesserte Beschaffung von Systeminformationen einer anderen Zelle
US20090047931A1 (en) * 2007-08-17 2009-02-19 Qualcomm Incorporated Method and apparatus for wireless access control
US20090227263A1 (en) * 2007-09-10 2009-09-10 Qualcomm Incorporated Method and apparatus for using load indication for intereference mitigation in a wireless communication system

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Publication number Publication date
WO2011005373A1 (en) 2011-01-13

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