LTE-Advanced (3GPP Rel-10) · LTE-Advanced (3GPP Rel-10) LTE-Advanced Enhanced LTE & additional...
Transcript of LTE-Advanced (3GPP Rel-10) · LTE-Advanced (3GPP Rel-10) LTE-Advanced Enhanced LTE & additional...
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LTE-Advanced (3GPP Rel-10)
LTE-Advanced Enhanced LTE & additional features to meet ITU-R IMT-Advanced minimum requirements
Additional features *Carrier aggregation *Downlink reference signals: Introduction of CSI-RS & URS in DL*Enhanced Downlink MIMO: support up to 8Tx*Uplink MIMO: support up to 4TxLayer 3 RelayHeterogeneous network
*Required to meet the ITU-R requirements
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LTE-Advanced (3GPP Rel-10)
Carrier aggregationLTE-Advanced requirement
Scalable transmission bandwidth up to 100 MHzBackward compatibility
Support of a large transmission bandwidthTwo or more component carriers (CCs) are aggregated to support transmission bandwidths up to 100MHz Allowed channel bandwidths for each component carrier
1.4 MHz, 3 MHz, 5MHz, 10 MHz, 15 MHz and 20 MHzSupports both contiguous and non-contiguous aggregations
A large contiguous band is not available in some parts of the world Physically disjoint bands -> a logically contiguous band
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LTE-Advanced (3GPP Rel-10)
Carrier aggregationCross-carrier scheduling
PDCCH on a carrier can schedule PDSCH (or PUSCH) on other carriers. Carrier Indication Field (CIF) in PDCCH indicates the scheduled carrierUseful for HetNet interference coordination
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Heterogeneous network (HetNet) Low power nodes are placed throughout a macro-cell layout
Low power nodes: picocell, femtocell, RRH, relay nodesInterference problems in HetNet
Large interference due to restricted access Femto (with CSG(Closed Subscribed Group)) – Macro interferenceFemto – Femto interference
Dominant interference condition may happen when a pico cell expands its cell range for traffic off-loading from a macro cell to a pico cell
LTE-Advanced (3GPP Rel-10)
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Heterogeneous network (HetNet) CA based solution
Basic signals/control channels are transmitted only on the main carrier
Non-CA based solution ABS(Almost Blank Subframe): Subframes with reduced transmit power (including no transmission) on some physical channels and/or reduced activityABS information is transferred from aggressor cells to victim cells
Aggressor cell
LTE-Advanced (3GPP Rel-10)
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Technologies for 3GPP Rel-11
CoMP (Coordinated Muti-Point Tx & Rx)CA enhancementEnhanced DL control channel(s)Further enhanced DL MIMOMTC (Machine Type Communications) & low cost MTCNetwork energy savingFurther LTE SON enhancementEnhancement of Minimization of Drive Tests
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CoMP (Coordinated Muti-Point Tx & Rx)
Cooperative multi-point transmission/receptionimplies dynamic coordination among multiple geographically separated transmission/reception points
Point: Set of geographically co-located antennasNote that sectors of the same site correspond to different points
improves the coverage of high data rates, the cell-edge throughput and/or to increase system throughput
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CoMP – Scenarios (1/2)
Scenario 1: Homogeneous network with intra-site CoMP
Scenario 2: Homogeneous network with high Tx power RRHs (remote radio heads)
eNB
Coordination area
High Txpower RRH
Optical fiber
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CoMP – Scenarios (2/2)
Scenario 3/4: Heterogeneous network with low power RRHs within the macro cell coverage where the transmission/reception points created by the RRHs have different cell IDs (scenario 3) or the same cell IDs (scenario 4) as the macro cell
Other scenariose.g., small cells with the same cell ID
Low Tx power RRH(Omni-antenna)
eNB
Optical fiber
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CoMP-Downlink Schemes
Joint Processing (JP)Joint transmission (JT)
PDSCH transmission from multiple points at a time
Dynamic point selection (DPS)PDSCH transmission from one point at a time
Dynamic multi-point cooperation
Coordinated Scheduling/Beamforming(CS/CB)
Scheduling/beamforming coordination among multi points
Semi-static multi-point coordination
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CoMP-Uplink Schemes
Uplink CoMP schemesJoint Reception (JR)
Data transmitted by the UE is received jointly at multiple points (part of or entire CoMP cooperating set) at a time, e.g., to improve the received signal quality
Coordinated Scheduling and Beamforming (CS/CB)User scheduling and precoding selection decisions are made with coordination among points corresponding to the CoMP cooperating setData is intended for one point only
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CoMP-Network Deployment and Operation
Intra-eNB cooperation JT/JRConventional sectored cells belonging to the same eNB
Collocated antennaseNB connected with remote radio heads (RRHs)
Geographically separated antennasConnection via optical fiber, latency ~ a few us
Inter-eNB cooperation CS/CBInformation exchange over X2 interface
Latency ~ 10ms or more, QoS is not guaranteed
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Enhanced DL Control Channel(s)
Based on considerations from CA Enhancement in relation to the provision of a new carrier type, CoMP, and DL MIMOEnhanced physical downlink control channel(s) that is/are able to operate on
legacy carriersnew carrier type
Enhanced physical downlink control channel(s) shall be able to support increased control channel capacityto support frequency domain ICICto achieve improved spatial reuse of control channel resourceto support beamforming and/or diversityto operate in MBSFN subframes (also in non-MBSFN subframes)to coexist on the same carrier as legacy UEs
It is also desirable for the enhanced physical downlink control channel
to be able to be scheduled frequency-selectivelyto be able to mitigate inter-cell interference
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Requirements of Rel-12 and Onwards
Capacity increase to cope with traffic explosionEnergy savingCost efficiencySupport for diverse application and traffic typesHigher user experience/data rateBackhaul enhancement
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Potential Technologies for Rel-12 and Onwards
Enhanced small cell Interference coordination / managementFrequency separation between macro and small cells with higher frequency band for the small cellsDynamic DL/UL configuration in TDDInter-site CA / macro cell assisted small cellsEnhanced discovery / mobilityWireless backhaul for small cell
Multi-antenna/site technologiesFurther CoMP/MIMO enhancements3D beamforming & Massive MIMO
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Potential Technologies for Rel-12 and Onwards
New procedures and functionalities for LTE to support diverse traffic types
Control signaling reduction, etc.
LTE Device to Device (D2D)D2D device discoveryD2D communications
Enhanced interworking with other RATs such as WiFi, HSPAContinuous enhancements for MTC, SON, MDT Advanced terminal receivers (assisted by network)Enhanced positioning
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Enhanced Small Cell
Further densification of the network: a key tool to improve traffic capacityMacro deployment heterogeneous deployment
Very difficult to get a new site for an additional macro base stationMajority of traffic in local/hotspot scenarios
Number of small cells in a macro coverage will continue to be increased
(Panasonic)
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Enhanced Small Cell
Heterogeneous deploymentMacro cell for full-area coverageSmall cells for very high traffic capacity and service level locallyIn small cell coverage,
Traffic dynamics will be largeRelatively low average load High instantaneous data rates
User terminals will be stationary or only slowly moving
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Enhanced Small Cell
Frequency separation between macro and small cells3GPP activities on heterogeneous deployments have up to and including Rel-11 primarily focused on same-frequency operationNew spectrum mainly at higher frequencies, 3.5 GHz and above
Higher frequency bands are less suitable for use within a macro deployment Primarily suitable for the small cells Small cells operating on higher frequency bands with the overlaid macro call operating on lower cellular bands
Benefits of frequency-separated deployments Relaxing the RF requirements for local-area access nodesAllowing for different duplex schemes in the wide-area and local-area layers
(NTT docomo)
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Enhanced Small Cell
Dynamic DL/UL configuration in TDDTo better handle the high traffic dynamics in a local-area scenario, where the number of terminals transmitting to/receiving from a small cell can be very small, dynamic TDD is beneficialDynamic TDD requires a frequency-separated small cell deployment to avoid inter-layer interference
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Enhanced Small Cell
Macro cell assisted small cells - Soft cell (Ericsson)Terminal has dual connectivity
to the wide-area layer through an anchor carrier used for system information, basic radio-resource control (RRC) signaling and possible low-rate/high-reliability user datato the local-area layer through a ultra lean booster carrier used for large amounts of high-rate user data
Benefits in terms of robustness and mobilityIn case the booster connection is lost the terminal is still connected through the anchor carrierMacro cell can also aid the terminal in reducing complexity and power consumption (e.g., small cell discovery)
Split of C-Plane and U-plane between macro & small cells (NTT docomo)
C-plane: Macro cell maintains robust connectivity and mobility using lower frequency bandsU-plane: Small cell provides higher throughput and more flexible / cost-energy efficient operations using higher/wider frequency bands
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Enhanced Small Cell
Inter-site CA (multi-flow aggregation)Backhaul with (limited bandwidth and) higher latency needs to be supported as well
In Rel-11, CoMP and CA solutions are limited to intra-site and fiber based fast backhaul scenarios
Inter-site CA is an alternative to fiber based cloud-RAN (Samsung)Traffic splitting in CN or macro cell?If splitting in RAN, how to transport user data over X2 interface?
Macro cell can handle traffic steering and control plane (Huawei)
Enhanced small cell discovery / mobilityInter-frequency measurement enhancements for small cells UE battery saving while achieving good small cell discoveryEfficient mobility among small cells based on the discovery
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(Enhanced) New Carrier Type
New carrier typeMinimizing the transmission of “always-on” signals
Reduced CRS(cell-specific reference signal) or CRS free carrierePDCCH for control signaling
BenefitsImproved network energy efficiency
Base stations can turn off transmission circuitry when there is no data to transmit
Reduced interference level at low-to-medium loadsNo interference when no traffic
NCT is not backwards compatibleNot all signals expected by legacy terminals will be transmittedDeployment of a NCT may, in practice, primarily be limited to frequency bands not yet used by LTE
TypesIn conjunction with CA only (in Rel-11)Stand-alone NCT
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Enhanced Small Cell
Wireless backhaul for small cellIn addition to wired backhaul, small cells need cost effective wireless backhaul solutionIn-band: need to enhance the DeNB-RN link capacityOut-of-band: multiple access using higher frequency over 10GHz
Higher order modulation for small cell accessSmall cell supports 256QAM to exploit higher SINR in its coverage
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Multi-antenna Technologies
3D beamformingBoost capacity in the urban jungle
Increase SINRSupport higher user densities
By using active antenna arrays at the base stationAdaptive UE-specific 3D MIMO/beamforming in both vertical and horizontal directions (MU-MIMO)Vertical cell splitting (sectorization)Proactive cell shaping
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Multi-antenna Technologies
Massive MIMO for higher frequency bands (over 10GHz)In higher frequency, antenna elements can be miniaturized and their number can be increased
Pass loss can be compensated for via larger beamforming gainAdaptive very narrow beamforming
Huge beamforming gain with compact-sized antenna at both BS and MS (suitable for the small cell deployment)
Adaptive Pencil-Beamforming(Samsung)
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LTE Device to Device
D2D use cases (3GPP SA1 ProSe)Commercial/social use
Finding friends that are in proximity and sharing dataProximity-based multiplayer gamingLocal advertisingEtc.
Network offloadingPublic SafetyIntegration of current infrastructure services
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LTE Device to Device
LTE D2D discovery (Qualcomm)Over the top providers are introducing proximity discovery & services (e.g. Foursquare Radar, Sonar, Glancee)
LTE operators can enable these services under their controlNetwork-assisted discovery
Resources semi-statically allocated by the RAN & time-syncedUEs transmit discovery signals within the discovery resourcesDiscovery signals encode informationUEs decode everyone else’s signals
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LTE Device to Device
Types of D2D communicationsIntra/inter-cell D2D unicast/relayD2D broadcast/multicast (point to multi-point direct communications)Relay for device out of coverageD2D unicast/broadcast for devices out of coverage
Intra-cell D2D unicast/relay
Inter-cellD2D
unicast/relay
D2D link
Cellular link
D2Dbroadcast/ multicast
D2D unicast/broadcastfor devices out of
coverage(for public safety)
Relay for device out
of coverage(for public
safety)
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LTE Device to Device
SpectrumShared spectrumDedicated spectrumDedicated spectrum shared by multiple operators
Approaches Network-controlled D2D
Connection controlResource allocationLink adaptation
UE-controlled D2DDistributed connection/link scheduling
Network- and UE-controlled D2DHybrid control by network and UE