LTE – EPS Overview
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LTE – EPS Overview
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EUTRAN Key Features Evolved NodeB •No RNC is provided anymore •The evolved Node Bs take over all radio management functionality.
•This will make radio management faster and hopefully the network architecture simpler IP transport layer •EUTRAN exclusively uses IP as transport layer UL/DL resource scheduling •In UMTS physical resources are either shared or dedicated •Evolved Node B handles all physical resource via a scheduler and assigns them dynamically to users and channels •This provides greater flexibility than the older system
QoS awareness •The scheduler must handle and distinguish different quality of service classes •Otherwise real time services would not be possible via EUTRAN •The system provides the possibility for differentiated services Self configuration •Currently under investigation •Possibility to let Evolved Node Bs configure themselves •It will not completely substitute the manual configuration and optimization.
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LTE – EPS Overview
EPC Key Features IP transport layer •EUTRAN exclusively uses IP as transport layer QoS awareness •The scheduler must handle and distinguish different quality of service classes •Otherwise real time services would not be possible via EUTRAN •The system provides the possibility for differentiated services Packet Switched Domain only •No circuit switched domain is provided •If CS applications are required, they must be implemented via IP •Only one mobility management for the UE in LTE. 3GPP (GTP) or IETF (MIPv6) option •The EPC can be based either on 3GPP GTP protocols (similar to PS domain in UMTS/GPRS) or on IETF Mobile IPv6 (MIPv6) Non-3GPP access •The EPC will be prepared also to be used by non-3GPP access networks (e.g. LAN, WLAN, WiMAX, etc.) •This will provide true convergence of different packet radio access system
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SAE: System Architecture Evolution SAE GW: Serving Gateway +PDN Gateway
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Other important requirements LTE-Advanced will be deployed as an evolution of LTE Release 8 and on new bands. LTE-Advanced shall be backwards compatible with LTE Release 8 in the sense that a LTE Release 8 terminal can work in an LTE-Advanced NW, an LTE-Advanced terminal can work in an LTE Release 8 NW Increased deployment of indoor eNB and HeNB in LTE-Advanced.
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LTE – EPS Overview
Support wider bandwidth Carrier aggregation to achieve wider bandwidth Support of spectrum aggregation Peak data rate, spectrum flexibility Advanced MIMO techniques Extension to up to 8-layer transmission in downlink Introduction of single-user MIMO up to 4-layer transmission in uplink Peak data rate, capacity, cell-edge user throughput Coordinated multipoint transmission and reception (CoMP) CoMP transmission in downlink CoMP reception in uplink Cell-edge user throughput, coverage, deployment flexibility Further reduction of delay AS/NAS parallel processing for reduction of C-Plane delay Relaying Type 1 relays create a separate cell and appear as Rel. 8 LTE eNB to Rel. 8 LTE UEs Coverage, cost effective deployment
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Key facts about CA functionality introduced in RL50
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Carrier Aggregation brings into life the LTE Advanced concept (as standardized in 3GPP Rel. 10 and later) in the Nokiaproduct to mitigate the challenge of fragmented spectrum
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Primary aim of the RL50 LTE 1089 feature (Carrier Aggregation 20 MHz) is to boost mean and peak user throughput via sending the user data simultaneously over two carriers
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Without CA functionality it is not possible to achieve peak UE throughput higher than 100 Mbit/s unless regular 15 or 20 MHz deployments are in place
Fundamentals of Carrier Aggregation •
To make the aggregation of carriers possible, regular cell (primary cell – PCell) is paired with additional logical cell (secondary cell – SCell) serving the same geographical site sector.
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This dependency could be made bi-directional – a first cell could play a role of a SCell as well.
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In RL50 inter-band carrier aggregation is supported only
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CA capability of the UE (for the involved band combination) must be in place
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DL non-GBR data could be sent to the CA capable UE via both PCell as well as SCell
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DL GBR data is sent via PCell only
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Whole uplink UE traffic (data as well as signaling) is handled via PCell only
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All cells handling CA UEs serve simultaneously also regular, non-CA UEs
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LTE – EPS Overview
RL60 embodiment of Carrier Aggregation functionality •
In principle, algorithms behind: •
configuring, parameterization and monitoring of Carrier Aggregation feature in the cell,
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adding/activation of SCell for the UE,
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scheduling of the DL non-GBR data in PCell and SCell,
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reporting of CQI/SR/RI/ACK/NACK etc.
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deactivation/release of SCell
are the same in RL60 and RL50
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• •
LTE 1558 Carrier Aggregation is the flagship RL45TD feature that brings into life the LTE Advanced concept (as standardized in 3GPP Rel. 10) in the NokiaTD-LTE product It is a counterpart to the available FDD features: •
LTE1089 DL Carrier Aggregation 20 MHz (RL50)
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LTE1332 DL Carrier Aggregation 40 MHz (RL60)
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LTE1558 implements certain existing FDD functionalities of LTE1089 and LTE1332 in TD-LTE (with some TD-specific adjustments)
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Primary aim of the feature is to boost mean and peak user throughput via sending the user data simultaneously over two carriers
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Maximum achievable peak user throughput could be doubled in contrast to non-CA case
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To make the aggregation of carriers possible, regular cell is paired with additional logical cell serving the same geographical site sector.
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This dependency could be bi-directional – this first cell could play a role of secondary cell as well.
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LTE 1558 supports only intra-band carrier aggregation for 20 MHz + 20 MHz channel bandwidths
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Only non-GBR data could be sent via secondary cell (SCell)
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DL GBR data is sent via primary cell (PCell) only
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All cells handling CA UEs serve simultaneously also regular, non-CA UEs
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There is no carrier aggregation in the uplink direction RA41202EN60GLA0
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Note: Carrier 1 could play a role of primary cell or secondary one. Similarly, Carrier 2 could be primary or secondary cell – in the context of Carrier Aggregation configuration
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• Uplink MIMO for up to 4 UE antennas Increase peak data rate, and average and the cell edge throughput Fall back to TX diversity available for data and control (use the power amplifiers of all antennas even if multi-stream doesn’t work)
Advancements in reference signal structure, channel sounding and feedback • DL MIMO for 8 TX antennas Increase peak data rate, and average and the cell edge throughput Release 8 LTE UEs support up to 4 TX antennas (which are actually combinations of the 8 physical antennas) Improved reference signal design, scheduling and feedback schemes
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• Joint Processing (JP): data is available at each cell in the CoMP set As if all sites formed a single multi antenna base station
• Coordinated Scheduling/Beamforming (CS/CB): data only at the serving cell scheduling coordinated among cells • Standardization will be done in Rel. 11 Utilizing enhanced reference schemes introduced for MIMO enhancements, which were already done forward looking to CoMP applications
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This feature is only supported with FSMF • CoMP cannot be done across FSPs • Max CoMP set size is 3 • CoMP is currently only supported within an eNB, Intra eNB CoMP • Each cell is only listed in a single CoMP set. • IRC should be selected for UL combining • Due to the fact that the feature LTE614 Distributed Sites is not supported together with this feature, the maximum distance between the FSM and the RF module is limited to 200 meters (see also LTE94 Feederless site). This is the only limiting factor for the placement of the RF units
• From the network perspective the eNB is the only RAN network element that is impacted from this feature. • Upto 9 CoMP sets can be defined as the maximum number of cells supported is 18 • The eNB does not raise an alarm due to broken Rx antenna as the functionality is not supported yet (feature LTE445 "Antenna Alarm with Rx Signal Comparison" is in RL70).In case both Tx- and Rx-branch of a cell are mapped to the same physical antenna, the eNB does rise an alarm due to detected Tx antenna failure. However, the eNB shall shutdown a cell with broken Tx antenna unless the management parameter txPathFailureMode has value 'keepCellInService'. • Since the UL control information (UCI) is multiplexed into the PUSCH in time and frequency domain, there is no difference between the UL-SCH coming along with the PUSCH and the UCI coming along with the PUSCH. So this means that also the UCI on PUSCH benefits from the combining gain using the received signal from the antennas of the selected neighboring cell. So this means that the CQI, Ack/Nack, PMI and rank coming along on the PUSCH will have improved performance if this feature is enabled. RA41202EN60GLA0
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Not Part of RL60
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The term “Heterogeneous Networks” does not necessarily refer to a specific technology or feature as such, but is instead used to describe networks that have both wide area and local area (small cell) deployments. In many expected deployment scenarios, heterogeneous networks spread across multiple radio access technologies. Autonomous or automated interference coordination and handover optimization in such hierarchical network architectures are key aspects of heterogeneous networks. Other coordination technologies like self-configuration and self-optimization have been covered under Self Organized/Optimized Networks (SON) and Minimized Drive Testing (MDT) related study and work items since Release 8.
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Small Cells networks operate on licensed spectrum. To maintain low costs they need to be highly autonomous. In USA and India there are physical boundaries within the country for the allocation of spectrum for a particular operator.
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Drivers for small cells: Coverage: • Improve indoor coverage
• Fill coverage gaps & holes • Fill new coverage areas Capacity: • Macro not feasible • Dense hotzone capacity • Offload from macro New opportunities: • Enterprise solutions – traffic offload
• New services • Fixed mobile convergence
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Illustration of automated traffic predictions with (1) demand prediction, (2) served demand mask, (3) un-served demand mask, and (4) proposed small cell design.
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Macro eNB (Flexi Multi BTS) The evolved Node B (eNodeB, eNB) supports the LTE air interface and also provides the packet-switched functionality of a traditional radio network controller (RNC). As a result, the Evolved UTRAN does not require a separate RNC network element. The main role of eNB is to provide radio access. Radio access is needed to provide connectivity between UEs and the network. The eNodeB is responsible for radio transmission and reception from the UE. This involves the following functionalities: •
Radio resource management (RRM) in general
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Radio bearer control
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Scheduling of user data
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Control signaling over the air interface
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Ciphering of user data over the air interface.
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ip packet header compression over the air interface
The area covered by a single eNodeB can be split into one or more cells - but typically three cells. The X2 interface between adjacent base stations supports intereNodeB handovers, although such handovers can also be performed in a nonoptimal way without the X2 interface. The NokiaeNodeB (Flexi Zone Micro BTS and macro eNB) is based on the Flexi Multiradio BTS. The network management solution is based on NetAct. in turn runs on the Advanced TCA (ATCA) hardware platform. The network management solution is based on NetAct.
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MME The Mobility Management Entity provides the control plane functionality in the Evolved Packet Core (EPC) network. This network element: •
Generates temporary identities and allocate them to Ues
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Make sure that the users in the idle state can be reached
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Manages the signaling during handovers
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Authenticates users, based on the data obtained from the Home Subscriber Server (HSS)
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Manages bearers in the user plane
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Manages Non-Access Stratum (NAS) signaling and related security
Note that no user plane traffic goes through the Mobility Management Entity. In the Nokia LTE solution, the MME is based on the Flexi Network Server (Flexi NS) software platform, which in turn runs on the Advanced TCA (ATCA) hardware platform. The network management solution is based on NetAct.
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SGW The Serving Gateway and PDN Gateway provide the user plane connectivity between the access network and the external packet data network (PDN), for instance the public Internet or an operator-owned network that provides IP Multimedia Subsystem (IMS) services. The Serving Gateway is responsible for packet forwarding, routing, and buffering of downlink data for UEs that are in the idle state. It also serves as a mobility anchor point during inter-eNodeB handovers. Note that for each UE associated with the Evolved Packet System, at a given point in time, there is only one Serving Gateway. PGW The PDN Gateway is the user plane gateway towards the packet data network (PDN). The PDN Gateway allocates IP addresses to mobile users, and provides policy enforcement functionality and charging support. It also serves as a mobility anchor point during inter-system mobility. If a UE is accessing multiple PDNs, there may be more than one PDN Gateway (or APN) for that UE. In the Nokia LTE solution, it is possible to implement the Serving Gateway and PDN Gateway either within a single node or as separate nodes. In either case, the solution is based on the Flexi Network Gateway (Flexi NG) software platform, which in turn runs on the Advanced TCA (ATCA) hardware platform. The network management solution is based on NetAct.
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LTE-A enables a smooth and backward compatible evolution of LTE towards true 4G performance •
LTE-A comprises of various tools to enhance mobile broadband user experience and network efficiency
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There are serious interdependencies between network implementation and the various tools of LTE-A, which require an experienced partner when planning and implementing LTE-A
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Nokia Solutions and Networks has always been at the forefront of LTE-A research and development, with a strong focus on real operator opportunities in terms of efficiency and user experience
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