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    06 itg524 darmstadt_belschner 06 itg524 darmstadt_belschner Presentation Transcript

    • Methods for Interference Coordination in LTE NetworksJakob Belschner, Deutsche Telekom LaboratoriesZarah Bleicher, University of Stuttgart
    • Outline What’s already there? Overview on Interference Coordination in LTE Release 8 What’s going to come? Multi Layer Networks with Femto Cells Exemplary interference coordination algorithms from literature Conclusions Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 2
    • What’s already there?Overview on Interference Coordination in LTE Release 8 Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 3
    • Overview on Interference Coordination in LTE Release 8 Textbox mechanisms in the standard Existing Headline  Three indicators to be transmitted via X2 interface  Scheduler using CQI feedback Communication via X2 interface: Overload indicator (Uplink) High interference indicator (Uplink) Relative narrowband transmission power indicator (Downlink) Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 4
    • What’s going to come?Multi Layer Networks with Femto Cells Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 5
    • Multi Layer Networks with Femto Cells Overview Textbox Headline Macro Cell Femto Cell Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 6
    • Multi Layer Networks with Femto Cells What‘s Headline Textboxrealistic to assume? Textbox Headline Implications  Very high number of femto cells in one macro  Configuration by operator not realistic (too cell sector high effort)  Femto cells have to be cheap!  Self-configuration  Reduced functionality Femto cell has to sense it’s environment via  Macro cell will most probably have no  Integrated receiver information about femto cells in it’s area  UE measurement report  Communication between femto cells and  Interference coordination algorithms without macro cells for interference coordination communication more realistic would have to be standardized and is  Close subscriber groups create new complicated interference scenario  Closed subscriber group New methods for interference coordination needed! Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 7
    • Multi Layer Networks with Femto CellsClosed subscriber group interference scenario Textbox Headline Downlink interference for user of macro base station not admitted to femto cell Textbox Headline for femto cell by macro cell user nearby Uplink interference Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 8
    • Multi Layer Networks with Femto CellsSpectrum allocation Textbox Headline between macro and femto cells Sharing of spectrum Partial Co-channel Dedicated Channel Assignment Spectrum usage mode Co-channel Assignment Partitioned spectrum usage: chosen, depending on the Shared spectrum: licensed spectrum divided into trade off between larger Co-channel frequency reuse separate portions BW and cross-layer interference. Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 9
    • Exemplary interference coordination algorithms fromliterature Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 10
    • Exemplary interference coordination algorithms fromliterature Textbox Headline Pool Femto Interference Source: Yi Wu “A Novel Spectrum Arrangement Scheme for Femto Cell Deployment in LTE Macro Cells” Criteria for adding a user into the FIP: UE moving speed: Femto aware CQI (Low speed macro UE reporting: is threat to femtocell) If CQI difference  Doppler Frequency between the two Femto-interference Pool: Estimation bands exceeds a Macro BS schedules UE certain threshold having potential threat on  Handover rate femtocells here No communication between femto and macro cell needed. Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 11
    • Exemplary interference coordination algorithms fromliterature TextboxSpectrum Sharing with Inner Femtocells Hybrid Headline Source: Yong Bai “Resource Coordination and Interference Mitigation between Macrocell and Femtocell”  Femto cells divided into inner and outer cells  Inner femto cells: Orthogonal mode with macro BS  Outer femto cells: Co-channel mode with macro BS  Uplink: Outer femto cell always has a spectrum part that is not used by macro UEs (MUEs) → UL interference from MUEs to femto cell can be avoided.  Downlink: FBS interfering MUE remains  Two approaches proposed to solve this  Require communication from macro cell to femto cell or MUE to femto cell. Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 12
    • Exemplary interference coordination algorithms fromliterature Textbox access Limited Headline Source: A. Valcarce et al. “Limited Access to OFDMA Femtocells”  Femto Cell: Closed user group, but:  Allow non-subscribers to access a limited amount of the femto cell resources  Non-subscribers should first try to connect to macro cell  A non-subscriber can by denied due to insufficient PRBs, i.e. if there are not enough PRBs left to guaranty minimal necessary throughput for this user.  As soon non-subscriber is granted access it does not:  Produce uplink interference to the femto cell  Suffer from downlink interference by femto cell  Commercially challenging, but not as much as open femto cell Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 13
    • Conclusions Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 14
    • Summary Multi layer networks create new interference scenarios  Esp. femto cells with closed user groups LTE release 8 interference coordination mechanisms not sufficient for multi layer networks Many promising concepts in literature Communication for interference coordination is critical  Mass market (home use): Maybe no communication possible at all  Enterprise solutions (office buildings): Communication between femto cells via backbone might be possible (→WiFi controllers) Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 15
    • Thanks for your attention! Methods for Interference Coordination in LTE Networks (ITG 5 2 4) v3.ppt 2/18/2010 16