Ericsson LTE presentation SEMINAR 2010.ppt

Editor's Notes

• #5: LTE network commitments – April 7, 2010 Norway TeliaSonera Launched 2009 Sweden TeliaSonera Launched 2009 Armenia Vivacell-MTS 2010 Canada Telus 2010 Canada Bell Canada 2010 China China Telecom 2010 China China Mobile 2010 Finland TeliaSonera 2010 Japan NTT DoCoMo 2010 Japan Emobile 2010 South Korea SK Telecom 2010 South Korea KT 2010 Sweden TeleNor Sweden 2010 Sweden Tele2 Sweden 2010 USA CenturyTel 2010 USA MetroPCS 2010 USA Verizon Wireless 2010 UAE Etisalat 2010 Canada Rogers Wireless 2010-11 Germany Vodafone 2010-11 USA Cox Comms 2010-11 South Africa Vodacom 2010-11 Germany T-Mobile 2011 Ireland Hutchison 3 2011 Japan Softbank Mobile 2011 Jordan Zain 2011 Portugal TMN 2011 South Korea LG Telecom 2011 USA AT&T Mobility 2011 USA Aircell 2011 Austria T-Mobile 2011-12 Austria Mobilkom Austria 2011-12 Austria Hutchison 3 2011-12 Austria Orange 2011-12 France Orange 2011-12 New Zealand Telecom NZ 2011-12 Japan KDDI 2012 Taiwan Chunghwa Telecom 2012 Uzbekistan MTS 2012 Australia Telstra To be confirmed Bahrain Zain To be confirmed Brazil Vivo To be confirmed Estonia EMT To be confirmed Finland DNA To be confirmed Finland Elisa To be confirmed France SFR To be confirmed Hong Kong SmarTone-Vodafone To be confirmed Hong Kong PCCW To be confirmed Hong Kong CSL Limited To be confirmed Hong Kong Hutchison 3 To be confirmed Hong Kong China Mobile To be confirmed Italy Telecom Italia To be confirmed Netherlands KPN To be confirmed Norway TeleNor To be confirmed The Philippines Piltel To be confirmed Russia Svyazinvest To be confirmed Saudi Arabia Zain To be confirmed Saudi Arabia STC To be confirmed Singapore M1 To be confirmed Singapore SingTel To be confirmed Singapore Starhub To be confirmed South Africa Cell C To be confirmed USA T-Mobile USA To be confirmed USA Commnet Wireless To be confirmed TRIALS Argentina Telefonica Australia Optus Belgium Telenet Brazil Telefonica Chile Entel PCS Chile Movistar Czech Republic O2 (Telefonica) France Bouygues Telecom Germany O2 (Telefonica) Hungary Pannon Hungary Magyar Telekom (T-Mobile Hungary) Indonesia Telkomsel Kazakhstan Vimpelcom Russia MTS Russia Vimpelcom Russia Tele2 Russia Russia Megafon Singapore SingTel Slovak Republic O2 (Telefonica) Spain Telefonica The Philippines Globe Telecom The Philippines Smart UK O2 (Telefonica) Ukraine MTS-Ukraine
• #8: Ericsson has a BHAG of a world in 2020 where there are 50B connections – the majority of these connections will be to machines, not people. Consequently, next generation wireless networks will have to handle massive numbers of connected devices, far greater than is possible today. Key Messages: Ericsson predicts that by 2020 there will 50 million connected ”devices”. The efficient design of LTE enables it to embrace the huge range of demanding solutions and services for monitoring and surveillance of billions and billions of machines as well as the high bandwidth demanding media related services. Slide is structured in 4 quadrents where the different ”devices” are illustrated in different groupings: Upper left hand quadrent: transportation industry with all types of vehicles Lower left hand quadrent: handheld devices e.g. Laptops, MIDs, digital cameras, PSP, handsets Upper right hand quadrent: household appliances, e.g. Fridge, dishwashers, ovens, lighting, heating, etc. Lower right hand quadrent: Other types of devices e.g. meters, vending machines, cash registers, etc.
• #11: Source: http://www.teliasonera.com/4g/faq-4g.html#
• #15: GSM, WCDMA and LTE are aligned with TD-SCDMA in 3GPP. Also CDMA camp , major operstors have decided or are investigating going to LTE LTE will become THE global standard, strong industry momentum behand LTE.
• #19: Key messages: Depending on the spectrum situation in the various countries, LTE systems will be introduced in a number of frequency bands around the world. In the US, the 700MHz has already been awarded to operators and here we see the Verizon Wireless (has already announced their deployment by end 2009 and has selected Ericsson as one of the key vendors) and AT&T were the big winners . . . In Europe, LTE will be deployed mainly in the 2.6Mhz band initally While in China, operators like China Mobile will deploy TD-LTE in the 2.3MHz band.
• #22: The 2x50 MHz arrangement is the most attractive one for markets with 698 – 806 MHz available for mobile services thanks to the good utilization of the band and that this arrangement provides contiguous sub-bands that make product implementation easier. From a market point of view this band arrangement also has advantages. Since the majority of the people in the world live in regions where this arrangement is applicable, it is expected to be supported by a massive economies of scale advantage. For this reason it could be considered not only for the APAC region, but also for other regions, e.g. Africa.
• #31: Drive test data, January 24-26th 2010, Stockholm ”Excal- Accuver” The colors represent ”area binning” over 40m, i.e. each dot represents the average of serveral measurements.
• #33: Soon to be upgraded to 20 MHz, from this we expect twice the speed. In addition, NW optimization will improve reduce pilot pollution and improve SINR. DL Data speed  measured using the official Swedish Consumer broad band Evaluation site ”Bredbandskollen”. A commercial LTE dongle, available in the stores in Stockholm, was used. SINR is taken from the LTE dongle (internal logging application). A screen shot of SINR was taken during the Download and upload. SINR is varying in time – the SINR data is hence associated with some uncertainty. The data is taken at random locations indoor and outdoor.
• #34: In uplink we currently only use max 15 out of 48 PRBs in uplink. Thus, we only get 30% of what we should get after SW upgrade to support 48 PRBs (on 10 MHz). UL Data speed  measured using the official Swedish Consumer broad band Evaluation site ”Bredbandskollen”. A commercial LTE dongle, available in the stores in Stockholm, was used. SINR is taken from the LTE dongle (internal logging application). A screen shot of SINR was taken during the Download and upload. SINR is varying in time – the SINR data is hence associated with some uncertainty. The data is taken at random locations indoor and outdoor. Note: Based on this data, no quantitative comparison of indoor and outdoor data speeds vs. SINR can be made.
• #35: For optimized HO settings: Interruption time measured in UE, from last IP package from source cell to first IP package received from target cell.
• #37: Dynamic coordination in UL scheduling/beam-forming between cell sites Reception and joint processing of signals received at multiple geographically separated sites
• #50: 3GPP specifices certain network elements for SAE/EPC. Within Ericsson, these network elemements translate into product like seen on tis slide. The MME is an evolution of todays WPP based SGSN, same HW & SW, MME as an ”application”. SGSN-MME 2009B first release. MME= Mobility Managament Entity A layered User management solution is needed for SAE if LTE to 2G/3G handovers are planned. HSS 5.0 (mono) and UDC R1 FP01 (layered). HSS= Home Subscriber Server For the SAE GW, Ericsson has two products. CPG (redback based) & MPG (Juniper based, evolution of todays GGSN). Converged Packet Gw 2009B and GGSN-MPG 2010A The PCRF function is handled by the SAPC, same product as used in SACC today. Main task: control of authorized services per user and QoS control per bearer (PDP context). SAPC 2009B
• #55: PCRF functionality Policy Control for IMS as well as non-IMS services Aware Traffic Management Fair Usage Policy Control for Mobile Broadband Standardized and open Gx, Rx, LDAP, SQL, SOAP interfaces SAPC evolves into a multi-access Policy Server 3GPP R8 Policy Control, e.g. for local breakout/roaming Converged Policy Control for fixed and mobile access Support Ericsson’s user data consolidation solution Current Performance (TSP6) Scalable up to 60 Million subscribers per node PCRF: Provides Service Data Flow gating Set QoS for each Service Data Flow Define charging for each Service Data Flow Enables Bearer QoS Control Correlation between Application and Bearer charging Notification of bearer events to the application function
• #56: Telecom grade characteristics High availability middleware, 99.9999 percent N+M redundancy, geographic redundancy Linear cluster scalability Capacity grows linearly as processors are added Up to 40 processor boards per cabinet EPC subscription management EPC authentication, authorization Attach/detach Mobility management Support for layered architecture user management solutions Home Subscriber Server (HSS) Evolution of Home Location Register (HLR) Contains subscriber data and authentication data Service information support – triggers, application server identities in the user profiles Subscription Locator Function (SLF) In case of several HSS servers in the network, SLF keeps track on which one that saves data for a user Maintain and provide Subscribtion data Provide Keys for Authentication and Encryption Maintain knowledge of visited MME/SGSN Maintain knowledge of used PDN GW
• #61: Operators are now emerging themselves into their own Metro Ethernet backhaul, re-using their own infrastructure with software upgrades, new cards to support Ethernet; preferring to adopt MPLS and MEF certified vendors to do everything including transporting TDM
• #66: WCDMA release 99 uses QPSK data modulation for downlink transmission. To support higher data rates, higher-order data modulation, such as 16QAM, can be used. Compared to QPSK modulation, higher-order modulation is more bandwidth efficient, i.e. can carry more bits per Hertz. However, higher-order modulation is also less robust and typically requires higher energy per bit for a given a given error rate. In case of interference-limited capacity, which is the normal case for WCDMA, the use of higher-order modulation is thus not efficient from a system capacity point-of-view. However, in case of shared-channel transmission, a significant part of the total cell power may instantaneously be used for transmission to a single user. In this case, the signal-to-interference ratio (SIR) may in some cases be relatively high, even in case of one-cell frequency reuse. Having to rely on QPSK modulation in such cases may lead to excess SIR, i.e. the channel conditions may support higher data rates than what can be achieved with QPSK (bandwidth limited capacity). Thus, higher-order modulation can be used together with shared-channel transmission to support higher data rates and achieve higher capacity, assuming it is used only when the radio-channel conditions so allow.
• #82: Located in the first n OFDM symbols where n  3 and consists of: Multiple PDCCH are supported and a UE monitors a set of control channels. CCs are formed by aggregation of control channel elements (CCE), each CCEs consisting of a set of resource elements. Different code rates for the control channels are realized by aggregating different numbers of CCEs. QPSK modulation is used for all control channels. Each separate control channel has its own set of x-RNTI.
• #86: In the downlink plain OFDM is used but in the uplink a special form of OFDM is used known as Single Carrier Frequency Division Multiple Access. This reduces the peak to average power ratio which is high with plain OFDM. A simpler/cheaper PA in the terminal can be used that drains the battery less fast (a factor of 2 to 3 times are mentioned in different external reports). Higher uplink system throughput and improved coverage and cell-edge performance are also enabled when using SC-FDMA in the uplink.
• #99: The eNode B has no knowledge of the UEs location or Timing Advance (TA). The UE commences its RACH attempt at what it believs is the start of the subframe. The eNode B uses the time delay between the start of the subframe and the commencement of the CP reception in order to calculate the TA required for subsequent UL transmissions.
• #100: The CP is used to allow frequency domain processing in the RA preamble detector in the eNode B. To allow correct detection of the RA preamble burst the CP duration (TCP) must be larger than the sum of the channel round trip delay plus the channel multipath delay spread plus the combined timing error of the eNode B and the UE.
• #101: Format 0: Max{Tprop} = 50 s  Max cell radius:  15 km Format 1: Max{Tprop}  260 s  Max cell radius:  80 km Format 2: Max{Tprop} = 100 s  Max cell radius:  30 km Format 3: Max{Tprop}  360 s  Max cell radius:  110 km The CP is used to allow frequency domain processing in the RA preamble detector in the eNode B. 3GPP Defines 4 different RA preamble burst formats for LTE The eNode B scheduler is responsible for assigning PRACH sub frames on the UL
• #105: There is also talk about MIMO routing which is another multi uset type of MIMO. This concept is in work and it isbeing standardized.
• #123: An E-RAB uniquely identifies the concatenation of an S1 Bearer and the corresponding Data Radio Bearer. When an E-RAB exists, there is a one-to-one mapping between this E-RAB and an EPS bearer of the Non Access Stratum. The LTE E-RAB is can be thought of a PDP Context of previous 3GPP releases. An EPS bearer/E-RAB represents the level of granularity for bearer level QoS control in the EPC/E-UTRAN. That is, Service Data Flows mapped to the same EPS bearer receive the same bearer level packet forwarding treatment (e.g. scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.). As can be seen in the slide, QoS is sent by the MME to the eNB in the E-RAB Setup Request.
• #133: Idle mode support is part of LTE basic (not feature controlled). Idle mode settings can impact the UE battery life. System Information is defined by the Master Information Block and System Information Blocks. Idle Mode tasks can be split into the 3 processes highlighted: PLMN Selection Cell Selection/Reselection Location Registration (TAU)
• #134: Cell selection occurs: after PLMN selection at state change from connected to idle mode or after a number of failed RRC connection requests The UE can used stored carrier information to speed up cell selection (i.e. when leaving RRC connected mode). A suitable cell is defined as: Fulfils the selection criterion (covered later) Is not barred Belongs to the PLMN and is not in listed in the UE as a forbidden Tracking Area When a suitable cell is found, the UE enters a “Camped Normally” state. In this state, the UE monitors triggering criteria for the Cell Reselection evaluation process. If it cannot find suitable cell, the UE enters an “any cell selection” state and looks for an acceptable cell. An acceptable cell is defined as: Fulfils the cell selection criteria Is not barred Belongs to any PLMN or tracking area If the UE is able to find an acceptable cell, it enters the “Camped on any cell” state. In this state, the UE: Receives no service from the network Can only make emergency calls Repeatedly attempts to find a suitable cell
• #142: Add descriptive speaker notes – keep in mind that those presenting may not be too familiar with your feature. Add in the current Release in the roadmap
• #163: An E-RAB uniquely identifies the concatenation of an S1 Bearer and the corresponding Data Radio Bearer. When an E-RAB exists, there is a one-to-one mapping between this E-RAB and an EPS bearer of the Non Access Stratum. The LTE E-RAB is can be thought of a PDP Context of previous 3GPP releases. An EPS bearer/E-RAB represents the level of granularity for bearer level QoS control in the EPC/E-UTRAN. That is, Service Data Flows mapped to the same EPS bearer receive the same bearer level packet forwarding treatment (e.g. scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.). As can be seen in the slide, QoS is sent by the MME to the eNB in the E-RAB Setup Request.
• #164: Each standardized QCI is related to a specific set of standardized QCI Characteristics (Resource Type, Priority, Packet Delay Budget and Packet Loss Rate), which are defined for the EPS bearer and used to pre-configure the network nodes (e.g., scheduling weights, active queue management thresholds, link layer protocol configuration, etc.) for the standardized QCIs. Note that the standardized QCI Characteristics are not signaled over any interface, but just specified in TS 23.401 to indicate the expected characteristics of the standardized QCIs. There are standardized QCIs and QCI Characteristics, but the operator may also define its own proprietary QCIs and QCI Characteristics
• #165: QOS HANDLING The LTE Quality of Service (QoS) Handling coordinates and assigns the appropriate QoS to other functions in LTE RAN. The RBS maps QCIs (Quality of Service Class Identifiers) to priorities for different Data Radio Bearers (DRBs) in the LTE radio interface and different data flows in the transport network. The LTE QoS Handling complies with the 3GPP Rel 8 QoS concept. It provides service differentiation per UE by support of multiple parallel bearers. To provide service differentiation in the uplink, traffic separation must be ensured between the different data flows within the UE. This is done by offering an operator-configurable mapping between QCIs and LCGs (Logical Channel Groups, also sometimes referred to as radio bearer groups). Moreover, service differentiation is enabled by mapping of QCIs to priorities as defined in 3GPP TS 23.203. In the uplink, these priorities will serve as a basis for the UE to establish differentiation/prioritization between its logical channels. Signalling Radio Bearers (SRBs) are assigned higher priority than Data Radio Bearers (DRBs). SRB1 has higher priority than SRB2. For the UL, the transport network benefits from QoS by mapping QCI to DiffServ Code Point (DSCP) in the RBS. This enables the transport network to prioritize between its different data flows over the S1 interface in the uplink and over the X2 interface for the downlink data in case of Packet Forwarding. For the DL, a similar mapping is performed in the S-GW for the S1 DL data. If a user has multiple bearers with different QCI, these users will be separated in the radio network into different bearers. This separation will achieve benefits for the end-user QoS as it removes the risk that one service such as file download would block the traffic for a voice call. All QoS class identifiers defined by 3GPP are accepted. QoS Handling is based on mapping QCIs received from the core network to RBS-specific parameters. This makes it possible to have different priorities and DSCP values. The LTE QoS Handling is realized by a central function in the RBS, which directly influences the radio and transport network behavior. The Scheduler is an essential QoS enabler. In the downlink, the Scheduler does not differentiate with respect to QCI. In the uplink, the scheduling in the RBS operates on Logical Channel Groups (LCGs) using similar scheduling strategies as in the downlink to grant resources.
• #166: Traffic policing is monitoring network traffic for conformity with a traffic contract and if required, dropping traffic to enforce compliance with that contract. Traffic sources which are aware of a traffic contract sometimes apply Traffic Shaping in order to ensure their output stays within the contract and is thus not dropped. Traffic exceeding a traffic contract may be tagged as non-compliant, dropped, or left as-is depending on circumstances . Traffic shaping provides a mean to control the volume of traffic being sent into a network in a specified period (bandwidth throttling), or the maximum rate at which the traffic is sent (rate limiting), or more complex criteria such as GCRA. This control can be accomplished in many ways and for many reasons; however traffic shaping is always achieved by delaying packets.
• #167: HEADER COMPRESSION AND DECOPMPRESSION In many services and applications e.g. Voice over IP, interactive games, messaging etc the payload of the IP packet is sometimes even smaller than a header. Over end-to-end connection, comprised of multiple hops the content of the IP header is extremely important however over just one link (UE to eNodeB , hop-to-hop) some information can be omitted as it will never change due to its static nature during a connection time. It is possible to compress those headers in many cases up to 90%. As a consequence link budget can be improved by several dB due to the decrease in header size. In the low bandwidth networks, using header compression results in a better response time due to smaller packet sizes. Header Compression has to be negotiated at the time of the link set up. Both sides of the link needs to be capable of running the same header compression algorithms. The header compression protocol specified in PDCP is based on the Robust Header Compression (ROHC) framework IETF RFC 3095. There are multiple header compression algorithms, called profiles, defined for the ROHC framework. Each profile is specific to the particular network layer, transport layer or upper layer protocol combination e.g. TCP/IP and RTP/UDP/IP. Header compression The header compression protocol generates two types of output packets: • compressed packets, each associated with one PDCP SDU • standalone packets not associated with a PDCP SDU, i.e. interspersed ROHC feedback packets A compressed packet is associated with the same PDCP SN and COUNT value as the related PDCP SDU. Interspersed ROHC feedback packets are not associated with a PDCP SDU. They are not associated with a PDCP SN and are not ciphered. Header decompression If header compression is configured by upper layers for PDCP entities associated with u-plane data the PDCP PDUs are de-compressed by the header compression protocol after performing deciphering.
• #168: Semi-Persistent Scheduling (SPS) Fully dynamic scheduling allows for flexibility but it also leads to high signaling overhead as a grant needs to be signaled in each scheduling instance, for example for each VoIP packet in case of VoIP. To limit the signaling load for sources with regular arrival rate a concept referred to as semi-persistent scheduling has been agreed in 3GPP. The idea is to assign resources on a long-term basis, for example using RRC (how to assign resources is not agreed in 3GPP). The eNB assigns semi-persistently time and frequency resources for the initial transmission attempts. All HARQ retransmissions are scheduled dynamically. This concept is illustrated above. Both in the uplink and the downlink there will only be a single MCS format assigned when SPS is activated and blind decoding is not needed. The figure shows an illustration of the semi-persistent scheduling concept and that resources for the initial transmissions are allocated on a long-term basis and retransmissions are dynamically scheduled.
• #174: LTE coverage will initially only be deployed in islands. Outside these islands, the subscriber must receive its services from a non LTE environment. This can either be a HSPA network, over which MMTel is run or a classical CS network without MMTel capabilities.
• #176: Terminating Access Domain Selection (T-ADS): Provides: Directs an incoming session to an ICS User; For one or more UEs of an ICS User: Influences the selection of one or more contacts amongst the registered contacts and; Influences the selection of an access network for delivery of the incoming session to the selected contact, or; Performs breakout to the CS Domain by fetching the CSRN. Takes into account the access network and UE capabilities, IMS registration status, CS status, existing active sessions, and operator policies.
• #180: [NOTE TO INSTRUCTOR – Slide has animation, click mouse to progress animation when the words <Click> appear ] As stated previously, the Self-Organising Network concept covers three different phases of the network life cycle; Self-configuration, self-optimisation and self-healing. These concepts will now be discussed in more detail. < Click > Self-Configuration Self-configuration process is defined as the process where newly deployed nodes are configured by automatic installation procedures to get the necessary basic configuration for system operation. This process works in pre-operational state. Pre-operational state is understood as the state from when the eNode B is powered up and has backbone connectivity until the RF transmitter is switched on. This is essential plug & play behavior for new network elements. The key areas is automated deployment of new base stations, which covers following activities: · automatic configuration of initial radio and transport parameters · automatic data alignment for neighbour nodes · automatic connectivity establishment · self-test · automatic inventory · automatic authentication and software download < Click > Self-Optimization The aim of self-optimization is to fine-tune initial parameters and dynamically recalculate these parameters in case of network and traffic changes. The optimization of the network shall be based on live measurement data. Self-optimization is an important improvement area due to the fact that current automatic optimization tools focus on small number of radio parameters and a lot of manual effort is required for optimization activities. The aim is to make following optimization activities automatic: · neighbour cell list optimization · interference control · handover parameter optimization · Quality of Service related parameter optimization · load balancing · RACH load optimization · optimization of home base stations < Click > Self-Healing Fault management should be simplified and automated via information correlation mechanisms. Operators will be responsible for definition of correlation rules and corrective actions to specific faults but the fault correction itself will be autonomous. Self-healing covers use cases such as cell outage detection and compensation via automated root cause analysis and corrective actions as such routing traffic to nearby cells. Another example is migration of unit outage based on automatic mechanisms for adaptation and reconfiguration of hardware.
• #181: [NOTE TO INSTRUCTOR – Slide has animation, click mouse to progress animation when the words <Click> appear ] The following is a description of the RBS Autointegration process from the Base Station Integration Manager (BSIM) perspective: < Click > 1. Configuration data processing starts when the user selects BSIM to prepare the RBSs for autointegration: • BSIM checks that all mandatory input data and files are present • BSIM creates and stores configuration data for O&M communication and RBS equipment on the SMRS (Software Management Repository Services), • If configuration over DHCP is used, then BSIM creates and stores RBS parameters in DHCP servers, • BSIM defines the RBSs and cells, and adds the information to the OSS-RC Network Resource Model (ONRM) • BSIM creates and stores transport network data and radio network data for each RBS internally in a planned area • BSIM prepares a field technician’s directory on the SMRS server with data to use for initiation of the autointegration at the RBS site • The OSS-RC performance management support service updates the statistics profiles and cell trace profiles with the new RBSs to be monitored • BSIM listens for RBS notifications on the node discovery interface < Click > 2. The technician takes the configuration files to site on the laptop. < Click > 3. Once on site the technician starts the Integrate RBS wizard and loads the input file. From this point, the remainder of the integration process is automatic. The following steps occur as part of this automatic process: O&M IP address is assigned to allow connection to the OSS site is configured Info/SMRS file info Keys are generated and security is signed The RBS undergoes upgrade procedures if required including a basic data load, software upgrade, a data configuration load from the OSS planned area and licences are installed if required setup of the S1 link commences Radio network is configured license key is activated The RBS is unlocks and a CV is created BSIM also makes the result of each Autointegration available for the user in a log file.
• #182: The Automated Neighbor Relations (ANR) feature is an optional feature introduced in release L10A for managing intra-LTE neighbor cell relations. ANR is standardized in 3GPP. On of the most time consuming tasks in today’s networks is the optimisation of handover relations. In these networks an operator needs to manually evaluate handover performance with the help of post-processing tools. In LTE networks, neighbor cell lists are still required. Automated Neighbor Relations (ANR) removes the need for configuring neighbor lists for intra-LTE handover. It is a new way of managing neighbors in a radio network. The neighbors list is built up automatically in the RBS. The RBS builds the list based on real measurement from the UE. The RBS ability to manage the addition and deletion of neighbour cell relations can be controlled by the operator via policy control settings. These policy control settings will be discussed in more detail shortly. Intra-LTE Neigbour cell relations can be added and deleted via the OSS-RC in a manner similar to that used for 2G and 3G networks if the operator chooses not to purchase the ANR feature. The ANR feature is activated via a software license key.
• #183: [NOTE TO INSTRUCTOR – Slide has animation, click mouse to progress animation when the words <Click> appear ] The Automatic Neighbor Relations function operates as follows: The UE is communicating with Cell A. When the session commenced, the UE was sent measurement control information by the serving RBS informing the UE of the parameters to be used to control mobility within the network. < Click > When the UE approaches the cell border it will detect the neighboring cell at a signal strength and/or quality which is sufficient to trigger the sending of a measurement report which contains the Physical Cell Identity (PCI) of the detected cell or cells. < Click > When the RBS receives a UE measurement report it checks its Neighbour Relation Table to determine whether or not the detected PCI is transmitted by a known neighbour cell. If the PCI is not in the Neighbour Relation table, then the RBS instructs the UE to read the E-UTRAN Cell Global Identifier (ECGI) of the cell transmitting the detected PCI. The ECGI information is transmitted on the Broadcast Channel (BCH) and is made up of the Cell Identity, the Tracking Area Code (TAC) and all available PLMN ID(s) of the related neighbour cell. < Click > The UE will read the broadcast channel of the detected neighbour cell. In order for the UE to read the Broadcast channel, the serving RBS may need to schedule appropriate idle periods to allow the UE to read the detected neighbour cell’s Broadcast Channel. < Click > The UE reports the E-UTRAN Cell Global Identifier (ECGI) of the detected neighbor cell back to the serving RBS. < Click > The serving RBS may decide to add this neighbour relation, based on the ANR policy control settings for the RBS. If the serving RBS does decide to add the neighbor relation it will use PCI and ECGI to lookup a transport layer address to the new RBS – either retrieving the transport address from the network or by having it locally configured. < Click > The Neighbour Relation Table (NRT) of the serving RBS will be updated to include the new neighbour. Changes to the NRT need to be updated in both the RBS and the OSS. The RBS informs the OSS of any updates or changes made to the Neighbour Relation Table by the Automatic Neighbour Relation function. < Click > If the ANR policy setting requires the configuration of an X2 link, then the serving RBS will trigger the X2 setup procedure. This procedure enables an automatic exchange of application level configuration data relevant to the X2 interface. For example, each RBS reports within the X2 SETUP REQUEST message to a neighbour RBS information about each cell it manages, such as the cell’s physical identity, the frequency band, the tracking area identity and/or the associated PLMNs. < Click > Finally, the UE will be sent a handoff direction message informing it to handoff to the new neighbour cell.
• #184: [NOTE TO INSTRUCTOR – Slide has animation, click mouse to progress animation when the words <Click> appear ] < Click > If implemented, SON functions such as ANR will be assisted by the initial tuning process. The ANR function relies on UE measurements to make changes to the NRT. The Ericsson Initial Tuning process for new LTE networks will generate UE traffic in the network which will allow for the ANR function to start optimising the neighbour relation table prior to the network accepting commercial traffic. < Click > SON and ANR policy settings will be fine tuned to match the life cycle requirements of the network. In a new network the Operator may require a very aggressive policy configuration which aims to react quickly to any changes required in the Neighbour Relation configuration. In more mature networks, the ANR policy settings may be more relaxed and respond to slowly to neighbour change requests. < Click > For ANR policy setting can include settings such as: The number of handover requests to be received by the RBS before an ncell is added The elapsed time since last use of an ncell relationship before it is deleted Should ANR only include measurements from handover requests or should the RBS request periodic measurements for all or a subset of UEs in a cell Should ncells be added if the "new cell" is not the best servering cells – should the 2nd, 3rd or 4th best server listed in a measurement report be added as an ncell Should all or some active mode UEs be asked to report servers and if so how many and how often Should all or some idle mode UEs be asked to report servers and if so how many and how often
• #185: The 3GPP Document 36.300 provides a framework for two possible methods for implementing Automatic PCI Configuration; the Centralised method and the Distributed method. In the Centralized PCI assignment method, which is shown above, the OSS signals a specific PCI value. The eNodeB then selects this value as its PCI. This is the solution preferred by vendors such a Ericsson and NSN. In the Distributed PCI assignment method, the OSS signals a list of PCI values. The eNodeB may restrict this list by removing PCI-s that are: a) reported by UEs; b) reported over the X2 interface by neighboring eNodeBs; and/or c) acquired through other implementation dependent methods, e.g. heard over the air using a downlink receiver. The eNB shall select a PCI value randomly from the remaining list of PCIs.
• #186: In LTE there are 64 preambles allocated for each cell, a subset of which can be reserved for dedicated use, for example for handover access (or for access to regain uplink time synchronization). The preamble implicitly contains a random ID which serves as a UE identifier. The Preamble sequence generation is described in TS 36211: Physical Channels and Modulation Number of preambles from each root sequence depends on Cell size The larger the cell, the larger the cyclic shift required to generate orthogonal sequences, and consequently the larger the number of ZC root sequences necessary to provide the 64 required preambles. Smallest cell: 64 preambles / root sequence Largest cell: 1 preamble / root sequence High-speed mode The relationship between cell size and the required number of Zadoff-Chu (ZC) root sequences allows for system optimization. The eNB should configure the cyclic shift offset independantly in each cell, bz the expected inter-cell interference and load increases as cell size decreases, therefore smaller cells need more protection from co-preamble interference than larger cells. It is recommended to use as few root sequence as possible in each cell in order to: reduce root sequence planning complexity reduce interference between preamble transmissions
• #187: Inter-Cell Interference Coordination (ICIC) Inter-cell Interference Coordination, located in eNB, has the task to manage radio resources (notably the radio resource blocks) such that inter-cell interference is kept under control. The specific ICIC techniques that will be used in E-UTRA are for further study. ICIC is inherently a multi-cell RRM function that needs to take into account the resource usage status and traffic load situation of multiple cells. According to a fairly broad consensus in 3GPP RAN1, the Release 8 LTE standard will not support ICIC in the downlink. Uplink inter-cell interference coordination consists of two interrelated mechanisms, the details of which are currently discussed within the 3GPP. The first part is a pro-active ICIC mechanism. The basic idea of this scheme is that a potentially disturbing eNB pro-actively sends a resource block specific indication to its potentially disturbed neighbor. This message indicates which resource blocks will be scheduled (with a high probability) with high power (i.e. by cell edge UEs). Thus this message allows the receiving eNB(s) to try to avoid to schedule the same resource blocks for its cell edge UEs. This way the pro-active scheme allows neighbor eNBs to reduce the probabilities of “exterior-exterior” (i.e. cell edge) UEs to simultaneously take into use the same resource blocks. In addition, the 3GPP also discusses the use of the overload indicator (OI) that was originally proposed for inter-cell power control purposes. It is currently agreed in 3GPP that the OI also carries information at the resource block granularity. As opposed to the pro-active scheme, the overload indication is a reactive scheme that indicates a high detected interference level on a specific resource block to neighbor eNB(s). The details of OI based ICIC and its joint operation with the pro-active scheme is FFS at 3GPP.
• #188: A separate Load Indication procedure is used over the X2 interface for the exchange of load information related to IC as shown in the figure. As these measurements have direct influence on some RRM real-time processes, the frequency of reporting is very high. The X2 signalling of UL HII and OI is explained as follows: UL HII (High Interference Indicator) + Target Cell IDs A2 level report on interference sensitivity per PRB The occurrence of high interference sensitivity, as seen from the sending eNodeB The receiving eNodeB should try to avoid scheduling cell edge UEs in its cells for the concerned PRBs UL OI (Overload Indicator) A report on interference overload per PRB The interference level experienced by the sending eNodeB on some resource blocks The receiving eNodeB may take such information into account when setting its scheduling policy For the DL: Max Tx Power per PRB An indication per PRB whether DL PRBs Tx power exceeds a threshold (FFS) The receiving eNodeB may take such information into account when setting its scheduling policy
• #189: Frequency-soft-reuse, also called Reuse-Partitioning, is an ICIC scheme for unicast in LTE. It basically divides the coverage area of a single cell into several regions, each region using its own reuse factor. The spectrum is also divided into partitions and then each partition into the desired number of reuse subsets. The basic scheme divides the cell in two concentric rings, the inner circle uses frequency-reuse factor 1 with restricted transmission power and the outer circle uses a higher reuse factor with maximum transmission power, normally reserved for the cell edge users. The figure shows an example of soft frequency-reuse with frequency-reuse 1-3 mixture. Each cell is assigned a color that corresponds to a specific offset value (n1, n2, n3). The assignment of the colors to the cells can be done via the OSS or dynamically between eNode Bs utilizing the X2 interface.