UMTS Overview

UMTS Overview

Presented By: Dost Muhammad

1Contents:UMTS ArchitectureUMTS Common TerminologiesPTML UMTS900 Trial Project Overview3G Basic KPIUMTS ArchitectureUMTSUMTS is a mobile cellular communications system belonging to the family of 3G systems defined in the IMT-2000 framework144 kbps: high-speed motor vehicles over large areas384 kbps: pedestrians standing or moving slowly over small areasSupport for 2.048 Mbps for office use

4UMTS ArchitectureThe UMTS Network Architecture consists:Core Network (CN) Universal Terrestrial Radio Access Network (UTRAN)

UMTS Architecture: CNThe Core Network consists of 3 domains:Circuit-switched domainRegister and service domainPacket-switched domainUMTS Architecture: CNThe Core Network consists of 3 domains:Circuit-switched domainRegister and service domainPacket-switched domain

UMTS Architecture: CNThe Core Network consists of 3 domains:Circuit-switched domainThe circuit-switched domain is a modified version of the Network Switching Subsystem(NSS), which we know from GSM. It is circuit-switched and consists of the Mobile Services Switching Center (MSC), which has been adapted for UMTS, and the Visitor Location Register (VLR)Register and service domainRegister domain consists of HLR,EIR, AuC. These are also used in GSMService domain consists of IN & other service development platformsPacket-switched domainThe Packet Switched Domain is a packet-switched network based on the current GPRS architecture.

UMTS Architecture: CN FunctionsThe Core Network provides the following functions:

Connection Management (CM)provides the bearer services and the procedures for circuit-switched connectionsSession Management (SM) responsible for the set up, monitoring and release of a packet-switched connection Mobility Management (MM), used to determine the location of a User Equipment so a connection can be set up.UMTS Architecture: UTRANThe UTRAN is similar to the Base Station Subsystem in the GSM network. It consists of the network elements responsible for Radio Resource Management.Each RNS manages the radio resources of all its connections.The RNS consists of a Radio Network Controller (RNC), which is similar to the GSM Base Station Controller (BSC), and of one or more Node Bs, which can be compared to the Base Station (BS) of GSM. The RNC is connected to the Node B via the Iub interface.

UTRAN FunctionsThe UTRAN provides the following functions:Radio Resource ControlAdmission ControlCongestion ControlCode AllocationPower ControlHandover ControlMacro diversity

UTRAN Functions:Radio Resource ControlManagement and release of radio resources is a function of the Radio Network ControllerRNC makes the required resources availableResource Control is required when resources are to be made available for macrodiversity or for improving the quality of the bearer service

UTRAN Functions: Admission ControlAdmission Control serves to avoid overload situations in the radio networkBased on measurements of the interference and the net load within the concerned cell, the RNC decides whether or not to allow further connections.Each new connection to a user equipment occupies some of the available resources. If there are no more resources available, then the RNC denies the new user equipment access to the network

UTRAN Functions: Congestion ControlIf the subscribers active in a cell cause an overload situation, Congestion Control provides functions that bring the system back into a stable and manageable state. Congestion Control can, for example,force a handover to a different Node Bforce a handover to the GSM systemreduce the data rate of individual active subscribersperform a controlled teardown of active connections.

14UTRAN Functions: Code AllocationThe Radio Network Controller is responsible for Code Allocation, i.e for assigning the codes to the individual connections. The RNC constantly monitors the codes used in its Node Bs.The codes must be unique within a single cell and its neighboring cells

15UTRAN Functions: Power ControlIn UMTS, the same frequencies are used in the active cells and their adjacent cells.Unnecessarily high transmit powers increase the level of interference within a cell, and thus reduce the network capacity. Near Far Problem: If two UEs at different distances to the Node B transmit with the same power, the User Equipment nearby will drown out the weak signal from the distant User Equipment. This is also called the near-far-problem. Power Control takes over the task of adapting the transmit power so the signals are transmitted with just enough power to be received by the Node B. To this, UMTS uses three different kinds of Power Control:Open Loop Power ControlClosed Loop Power Control

16UTRAN Functions: Handover ControlIn UMTS, as elsewhere, there is the possibility of switching the connection if the transfer quality worsens. This process is called handover. There are two types of handover in UMTS:Soft Handover (Soft - and Softer Handover)radio links are added and removed in a way that the UE always keeps at least one radio link attached to itselfHard Handover (Inter-Frequency or Inter-System Handover)old radio links in the UE are removed before the new radio links are established17UTRAN Functions: Handover Control

Soft HandoverLoad sharingNo service disruptionHard HandoverCompressed modeService disruption18UTRAN Functions: Macro DiversityThe macro diversity function allows the User Equipment to be connected to several cells simultaneously.Advantages of Macro diversityQuality of communication improvesUE can transmit with less powerThus, less interference

19Common Terminologies of UMTSUMTS Common TerminologiesCells grow as the number of users shrinks and shrink as the number of users increases.This phenomenon is called Cell Breathing More users means more codes, more radio frequency emission.... Because everybody using a different code to yours is heard by your phone (as well as the base station) as noise, the noise floor rises and drops with load. A higher noise floor leads to increased transmission errors and reduced service quality requiring lower data rates.More noise, means that the users furthest in propagation terms from the base station can no longer maintain the connection. There error rate rises, data rate must drop. They either drop out or must be transferred (handover) to another base station

21UMTS Common TerminologiesThere is a Serving RNS (SRNS) for the connection between the User Equipment and the Core Network.The User Equipment, however, can also be connected to further RNSs, if additional radio resources are required, e.g. for a soft handover. These are then called Drift Radio Network Subsystems (DRNS). The combination of the data, as well as the signaling between the Radio Network Controllers is done by the Iur interface.

22UMTS Common TerminologiesA hard handover is performed between two cells using different bearer frequencies. In this procedure, the User Equipment looks for new bearer frequencies without letting go of the active connection. To achieve this, in the FDD mode, the Wideband CDMA uses a compressed mode to measure other frequencies. The compressed mode creates gaps in the connection, without losing any data. When the handover is performed, the old radio link is released while the connection is taken over by a new cell with a new frequency. There is no interruption in the transmission during this procedure23UMTS Common TerminologiesWhen the number of strong cells exceeds the active set size, there is pilot pollution in the area. Typically the active set size is 3, so if there are more than 3 strong cells then there is pilot pollution.Definition of strong cell: pilots within the handover window size from the strongest cell. Typical handover window size is between 4 to 6dB. For example, if there are more than 2 cells (besides the strongest cell) within 4dB of the strongest cell then there is pilot pollution

24UMTS Common TerminologiesRSCP is the received signal code power from the CPICH channel and it is usually constant in a cell and it gives an indication of the level in the areaRSSI: is the received signal strength indicator and it is the total power with the noise.Ec/N0 : is the signal chip power and it is equal to RSCP/RSSI or the code power over the (noise+code power)25UMTS Common TerminologiesA rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" called fingers. Each finger independently decodes a single multipath component; at a later stage the contribution of all fingers are combined in order to make the most use of the different transmission characteristics of each transmission path. This could very well result in higher signal-to-noise ratio (or Eb/N0) in a multipath environment than in a "clean" environment.

26PTML UMTS Project OverviewPTML UMTS900 Project OverviewIn current Ufone network, there is 7.6MHz bandwidth in GSM900 and 6MHz in DCS1800Major TRX configuration is in GSM900M network. To deploy UMTS900 in Ufone network, need to get minimum 4.2MHz frequency bandwidth from GSM900 Therefore, it is required to expand DCS1800 TRXs and downgrade huge GSM900 TRXs UMTS900 trial will be conducted for indoor coverage scenarioFor this purpose, GSM900 refarming will be required.28PTML UMTS900 Project OverviewChanges in existing Network

New RNC will be installedAll BTS in trial location will be swapped to DBS3900 which can support 2G&3GSoftware licenses & 3G data configuration for interfaces in the core network29PTML UMTS900 Refarming Solution

Advantage:Sandwich Allocation-No interference with other operators.BCCH Planning Strategy: 51-62 ARFCNs to be used for BCCH in buffer zone cells. 44, 45, 46 and 51-62 to be used in the synchronous neighbors of buffer zone cellsTCH Planning strategy: |25, 26, 48, 49| to be used as 900 band MA list in buffer zone cell. 1800 band MA to remain the same.30PTML UMTS900 Project Overview-Buffer Zone Planning

31PTML UMTS900 Project Overview-Refarming StepsG1800 ExpansionG1800 OptimizationTraffic MigrationMR data CollectionNew Frequency GenerationLoad New Frequency Performance MonitoringGSM offloadG900 OptimizationU900 On Air

3G Basic KPI3G Basic KPI: RRC success RateRRCallows a dialogue between the RAN and the UE and also between the core network and the UE. AnRRC connection is a logical connection between the UE and the RAN used by two peer entities tosupport the upper layer exchange ofinformation flows. There can only be oneRRCconnection per UE. Several upper layer entities use the sameRRCconnection3G Basic KPI: RRC success RateRRC Key FunctionsEstablishing, re-establishing, maintaining and releasing the RRC connection (i.e. the first signaling connection for the UE) between the UTRAN and the UEEstablishing, re-configuring and releasing the radio access bearers in the user plane of layer 2 and layer 1Evaluation, decision-making and execution relating to RRC connection mobility (e.g. handover, cell/paging area update procedures and so on) during an established RRC connection

The formula of RRC Setup Success Rate: RRC Setup Success Rate = (RRC Connection Setup Success / RRC Connection Request) 100%

353G Basic KPI: RAB Success RateWhena connectionis requested,bearers are allocated by a bearer translation function. Thisfunction correlatesthe requestedattributes with the list of supported bearers and makes an appropriate choiceProvide information between a UE and thecore network on the quality requirements that must be satisfied for a service. This Quality of Service (QoS) is expressed by parameters such as data rate, block size, and error rate. The QoS required differs depending on the service

3G Basic KPI: RAB Success RateThe formula of RAB Establishment Success Rate: RAB Setup Success Rate = RABAssignment Success / RAB Assignment Request 100%

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