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RNC - AN INTRODUCTION

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RNC - AN INTRODUCTIONSlide title In CAPITALS 50 pt Slide subtitle 32 pt
RNC - AN INTRODUCTION
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
UTRAN TOPOLOGY
Top right corner for field-mark, customer or partner logotypes. See Best practice for example.
Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Radio Access Network (RAN)
When evolving into the third generation, the mobile access network will use ATM and IP to provide efficient and flexible transport and routing capabilities. Packet switching technologies will also be adapted to support real-time voice traffic all the way up to and including the terminals. An important component of the new mobile networks is the Cello transport platform for access products. Initially optimised for mobile technology, Cello is now being introduced as a switching node for packet transport. Several Ericsson products are being built on this platform, including media gateways, IP routers, Radio Base Stations (RBSs) and Radio Network Controllers (RNCs).
UMTS Radio Access Network (UTRAN)
UMTS Terrestrial RAN (UTRAN) consists of RNCs, RBSs, Radio Access Sub network Operations Support (RANOS) and the Tools for Radio Access Management (TRAM).
The RBS provides radio resources and maintains the radio links to end-user equipment. The main tasks of the RNC are to manage radio access bearers for user data transport to manage and optimise radio network resources and to control mobility.
UTRAN employs two Asynchronous Transfer Mode (ATM) Adaptation Layers (AAL). The new specially designed AAL2 is used for low-delay real-time connections and AAL5 is used for packet-switched connections not sensitive to delays, and for control and network management signaling.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Iub
(NBAP)
Iu Interface between an RNC and Circuit Switched and Packet Switched Core Networks. The interface is used for traffic related signaling. This includes both RANAP control signaling and user data transfer using frame protocols and tunnelling protocols.
Iub Interface between an RNC and an RBS used for traffic related signaling. This includes both NBAP control signaling and user data signaling using frame protocols.
Uu Interface between an RNC and a UE. The layer 1 part of Uu is terminated in the RBS. Layer 2 part is terminated in RNC. Part of layer 3 is terminated in RNC.
Mur Management interface provided by the RNC. It is used for element management and network management. Users of the interface may be a thin client or RANOS.
Mui Management interface provided by the OMINF. OMINF includes functions to support the infrastructure of the Operation and Maintenance network for UTRAN.
Iur This interface is between an RNC and another RNC. The interface is used for user data and control related signaling.The control signaling is done over the RNSAP protocol and the user data transfer is using Frame Protocols
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
SRNS
Iur
DRNS
UE
Iu-cs
Iu-ps
Each RNS is responsible for the resources of its set of cells.
For each connection between User Equipment and the UTRAN, One RNS is the Serving RNS. When required, Drift RNSs support the Serving RNS by providing radio resources as shown in figure. The role of an RNS (Serving or Drift) is on a per connection basis between a UE and the UTRAN
Controlling RNC: role an RNC can take with respect to a specific set of Node B's
There is only one Controlling RNC for any Node B. The Controlling RNC has the overall control of the logical resources of its node B's.
Radio Network Subsystem: RNS can be either a full UTRAN or only a part of a UTRAN. An RNS offers the allocation and release of specific radio resources to establish means of connection in between an UE and the UTRAN
A Radio Network Subsystem contains one RNC and is responsible for the resources and transmission/reception in a set of cells.
Serving RNS: role an RNS can take with respect to a specific connection between an UE and UTRAN. There is one Serving RNS for each UE that has a connection to UTRAN. The Serving RNS is in charge of the radio connection between a UE and the UTRAN. The Serving RNS terminates the Iu for this UE.
Drift RNS: role an RNS can take with respect to a specific connection between an UE and UTRAN. An RNS that supports the Serving RNS with radio resources when the connection between the UTRAN and the UE need to use cell(s) controlled by this RNS is referred to as Drift RNS.
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
RADIO ACCESS BEARERS
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
A UMTS Bearer is a UMTS service providing an application using the UMTS network with the ability to send and receive data over the UMTS network with a specific Quality of Service (QoS).
Network Services are considered end-to-end, this means from a Terminal Equipment (TE) to another TE. An End-to-End Service may have a certain Quality of Service (QoS) which is provided for the user of a network service. It is the user that decides whether he is satisfied with the provided QoS or not.
To realise a certain network QoS a Bearer Service with clearly defined characteristics and functionality is to be set up from the source to the destination of a service. A bearer service includes all aspects to enable the provision of a contracted QoS. These aspects are among others the control signalling, user plane transport and QoS management functionality.
A Radio Access Bearer (RAB) represents a bearer between the UMTS Core Network Edge Node (SGSN) and the UE. Each Bearer is associated with either the Packet Switched or Circuit Switched domain and provides a specific Quality of Serivce. Quality Of Service in UMTS is divided into four classes, Conversational, Streaming, Interactive and Background and is also characterised by maximum bitrate, guaranteed bitrate, transfer delay, priority, error rate etc.
RNC Concepts - Radio Access Bearer
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
RNC Concepts - Radio Access Bearer
TE
MT
RAN
CN
EDGE
NODE
CN
Gateway
TE
UMTS
Bearer Service
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Interactive RAB (Internet access - PS)
Conversational RAB for UDI of 64 kbps (H.324M multimedia - CS)
Streaming RAB (CS) offers support for variable rate circuit switched data up to 57.6 kbps
Streaming RAB (PS) offers support for guaranteed rate packet switched data
Multiple RABs offers support for multiple RABs configured simultaneously to the same UE
one or more PS RABs together with maximum one CS RAB
Multiple PS RABs
Two classes of Radio Access Bearer Services are provided:
a) Services with resource reservation and fixed throughput, e.g. speech.
b) Services tolerating a variable throughput, e.g. Best Effort IP Packet Data.
The function is initiated from CN, over the Iu interface, by sending the RANAP message RAB Assignment Request towards UTRAN, asking for a RAB to be set up towards a UE for which an RRC connection already exists. RNC then checks if the requested type of bearer can be provided or not (admission control).
If the request comes from the circuit switched core network (request of type a above), RNC then sets up a terrestrial link (AAL2 connection) between CN and UTRAN. Resources in RNC and Node B are allocated (including among other things allocation of new uplink and downlink channelisation codes for the physical channel, if there is a need to increase the bandwidth), a terrestrial link (AAL2 connection) is set up between RNC and Node B, and Node B connects the new bearer service to the existing dedicated radio link upon request from RNC. The UE is then informed about the new RAB via Radio Resource Control (RRC) signaling from RNC. Finally, CN is informed that the new RAB is established through the RANAP message RAB Assignment Complete.
If the request instead comes from the packet switched core network (for R1 only request of type b above) the handling is the same as above except that no terrestrial link needs to be set-up between CN and UTRAN since the transport layer for user data is already established via network management (O&M) functions in this case.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RAB Id
Included in the RANAP RAB Assignment Request to identify a specific RAB instance for a specific UE connection. Unique to the CN and UE connection
Internal RAB Id
RNC internal identifier representing the RAB type. Where multiple instances of a RAB type are supported, multiple Internal RAB Ids are defined
RNC Concepts - Radio Access Bearer Identities
SRB Only: 0
Conv CS Unknown Second (reserved): 3
Conv PS Speech: 4
Conv PS Unknown Second (reserved): 6
Streaming CS Unknown: 7
Streaming PS Unknown Second (reserved): 9
Interactive PS First: 10
interactive PS Second: 11
Interactive PS Third: 13
Internal RAB Id Mapping
a) Services with resource reservation and fixed throughput, e.g. speech.
b) Services tolerating a variable throughput, e.g. Best Effort IP Packet Data.
The function is initiated from CN, over the Iu interface, by sending the RANAP message RAB Assignment Request towards UTRAN, asking for a RAB to be set up towards a UE for which an RRC connection already exists. RNC then checks if the requested type of bearer can be provided or not (admission control).
If the request comes from the circuit switched core network (request of type a above), RNC then sets up a terrestrial link (AAL2 connection) between CN and UTRAN. Resources in RNC and Node B are allocated (including among other things allocation of new uplink and downlink channelisation codes for the physical channel, if there is a need to increase the bandwidth), a terrestrial link (AAL2 connection) is set up between RNC and Node B, and Node B connects the new bearer service to the existing dedicated radio link upon request from RNC. The UE is then informed about the new RAB via Radio Resource Control (RRC) signaling from RNC. Finally, CN is informed that the new RAB is established through the RANAP message RAB Assignment Complete.
If the request instead comes from the packet switched core network (for R1 only request of type b above) the handling is the same as above except that no terrestrial link needs to be set-up between CN and UTRAN since the transport layer for user data is already established via network management (O&M) functions in this case.
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
RADIO BEARERS
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Control Plane
The Control Plane implements the control of the Radio Access Bearers and the connection between the UE and the Network from different aspects (Requesting the service, controlling different transmission resources, handover etc). Also a mechanism for the transparent transfer of NAS messages is included.
The Control Plane Includes the Application Protocol, i.e. RANAP, RNSAP or NBAP, and the Signalling Bearer for transporting the Application Protocol messages.
User Plane
The User Plane implements the actual radio access bearer service, i.e. carrying user Data/Data Stream(s) through the access stratum The Data Stream(s) is/are characterised by one or more frame protocols specified for that interface.
RNC Concepts - Control and User Planes
NAS - Non Access Stratum
e.g. messages that are ‘transparent’ to the RNC, Location Area Update or if UE is on CS call and wants to set-up a PS call it will send a transparent message through the RNC to the PS CN to initiate call set up.
These messages are passed transparently through the RNC as the RNC will not perform any action upon them. If a UE is not connected to the UTRAN then its location is only known by the CN, thus if the UE moves into a new location area then it must report this to the CN, it will send this location area update as a NAS message. The NAS message is received by the RNC which peeks at it to see that it is a NAS message and forwards it toward the CN (see later slide on Location Area Update)
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RNC Concepts - Radio Interface Protocol Architecture
The radio interface protocols are required to set up, reconfigure and release radio bearer services
L3 - Network Layer
L2 - Datalink Layer
L1 Physical layer
L3 Radio Resource Control (RRC)
Establishment, maintenance and release of Radio Bearers (RB) for control and user data
Establishment, maintenance and release of related radio resources between UE and UTRAN
L2 Packet Data Convergence Protocol (PDCP)
IP header compression
L2 Radio Link Control (RLC)
Segmentation and re-transmission services for both control and user data
L2 Media Access Control (MAC)
Mapping of Logical channels to Transport channels
Transport Format and Transport Format Combination selection
Execution of switching between common and dedicated transport channels.
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
A Radio Bearer (RB) represents a bearer between the UTRAN and the UE. Therefore RABs are realised via bearers between the Core Network and UTRAN and Radio Bearers between UTRAN and UE. In general there is a one to one mapping between RABs and RBs. Speech RAB is an exception where each 20ms sample of speech is coded into three classes, A, B and C with different requirements on channel coding due to different sensitivity to errors. Each class is transferred via a separate radio bearer.
Signalling Radio Bearers (SRB) are defined to allow control plane signalling between UTRAN and the UE and between the UMTS Core Network (Non Access Stratum) and the UE. They represent the bearer between the UTRAN and the UE over which such signalling is transferred. There are four SRBs, SRB 1, 2, 3 and 4 for dedicated control channel (DCCH) signalling with:
SRB 1 used for RRC unacknowledged mode
SRB 2 for RRC acknowledged mode
SRB 3 for Non Access Stratum high priority Signalling
SRB 4 for Non Access Stratum low priority Signalling
SRB 0 is used for common control channel (CCCH) signalling
Signalling between the UTRAN and the Core Network is via Signalling Connection Control Part (SCCP) connections, with a SCCP connection (a logical connection over a physical link) established for each UE to each Core Network (PS and CS) as needed.
RNC Concepts - Radio Bearers
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RB Identity
UTRAN identifier configured in UE to represent a specific Radio Bearer
RNC is responsible for allocation of RB Identity, based on hardcoded table
Incoming CN Relocation can trigger flexible allocation of RB Identity
RNC Concepts - Radio Bearer Identities
SRB1: 1
SRB2: 2
SRB3: 3
SRB4: 4
Conv CS Unknown: 12
RB Id Mapping
a) Services with resource reservation and fixed throughput, e.g. speech.
b) Services tolerating a variable throughput, e.g. Best Effort IP Packet Data.
The function is initiated from CN, over the Iu interface, by sending the RANAP message RAB Assignment Request towards UTRAN, asking for a RAB to be set up towards a UE for which an RRC connection already exists. RNC then checks if the requested type of bearer can be provided or not (admission control).
If the request comes from the circuit switched core network (request of type a above), RNC then sets up a terrestrial link (AAL2 connection) between CN and UTRAN. Resources in RNC and Node B are allocated (including among other things allocation of new uplink and downlink channelisation codes for the physical channel, if there is a need to increase the bandwidth), a terrestrial link (AAL2 connection) is set up between RNC and Node B, and Node B connects the new bearer service to the existing dedicated radio link upon request from RNC. The UE is then informed about the new RAB via Radio Resource Control (RRC) signaling from RNC. Finally, CN is informed that the new RAB is established through the RANAP message RAB Assignment Complete.
If the request instead comes from the packet switched core network (for R1 only request of type b above) the handling is the same as above except that no terrestrial link needs to be set-up between CN and UTRAN since the transport layer for user data is already established via network management (O&M) functions in this case.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RB Type
RNC MOM enum used to distinguish Radio Bearer specific MO instances (UeRcRb, UeRcTrCh etc)
Used internally in UEH to distinguish different services (speech, packet, etc)
Used in UEH for transport bearer handling (determination of transport bearers to add/remove, identifying specific transport bearer instances etc.)
RNC Concepts - Radio Bearer Types
uehRbRrc: 0
uehRbSpeech: 1
uehRbPacket: 2
uehRbCsFix: 3
uehRbCsVar: 4
uehRbPsStreaming 5
uehRbPacketAdch 6
uehRbPacketHs 7
uehRbPacket2: 8
uehRbPacket3: 9
uehRbPacketHs2: 10
uehRbPacketHs3: 11
uehRbpacketAdch2: 12
uehRbPacketAdch3: 13
uehRbPsStreamingHs: 14
uehRbPsStreamingAdch 15
a) Services with resource reservation and fixed throughput, e.g. speech.
b) Services tolerating a variable throughput, e.g. Best Effort IP Packet Data.
The function is initiated from CN, over the Iu interface, by sending the RANAP message RAB Assignment Request towards UTRAN, asking for a RAB to be set up towards a UE for which an RRC connection already exists. RNC then checks if the requested type of bearer can be provided or not (admission control).
If the request comes from the circuit switched core network (request of type a above), RNC then sets up a terrestrial link (AAL2 connection) between CN and UTRAN. Resources in RNC and Node B are allocated (including among other things allocation of new uplink and downlink channelisation codes for the physical channel, if there is a need to increase the bandwidth), a terrestrial link (AAL2 connection) is set up between RNC and Node B, and Node B connects the new bearer service to the existing dedicated radio link upon request from RNC. The UE is then informed about the new RAB via Radio Resource Control (RRC) signaling from RNC. Finally, CN is informed that the new RAB is established through the RANAP message RAB Assignment Complete.
If the request instead comes from the packet switched core network (for R1 only request of type b above) the handling is the same as above except that no terrestrial link needs to be set-up between CN and UTRAN since the transport layer for user data is already established via network management (O&M) functions in this case.
Top right corner for field-mark, customer or partner logotypes. See Best practice for example.
Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
dedicated to the transfer of a specific type of
information over the radio interface.
Transport Channel:
er to Layer 2 for data transport between
peer L1 entities are denoted as Transport
Channels. Different types of Transport
Channels are defined by how and with
which characteristics data is transferred
on the physical layer, e.g. whether using
dedicated or common
In FDD mode, a Physical Channel is defined
by code, frequency and, in the Uplink, relative phase (I/Q). In TDD mode, a physical Channel is defined by code, frequency, and time slot.
Logical channels describe the type of information to be transmitted, transport channels are the ‘transmission media’ providing the radio platform through which the information is actually transferred.
The term physical channels means different kinds of bandwidths allocated for different purposes over the Uu interface.
Instead of physical channels the RNC sees the transport channels. Transport channels carry different information flows over the Uu interface and the physical element mapping these information flows to the physical channels is the BS. Logical channels are not actually channels as such, rather they can be understood as different tasks the network and the terminal should perform in the different moments of time.
E.G. The PCH carries Paging information (i.e. PCCH), then S-CCPCH carries two transport channels in it, one of them being the PCH.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
S-CCPCH (DL)
PICH (DL)
Dedicated Physical Control Channel
DPCH - Dedicated Physical Channel
LOGICAL CHANNELS (Data transfer services of the MAC layer defined by the type of information transferred.)
Control Channels (for control plane information)
Broadcast Control Channel (BCCH) A downlink channel for broadcasting system control information.
Paging Control Channel (PCCH) A downlink channel that transfers paging information.
Dedicated Control Channel (DCCH) A point-to-point bi-directional channel that transmits dedicated control information between Ue and CN.
Common Control Channel (CCCH) A bi-directional channel for transmitting control between the CN and Ues (always mapped into RACH/FACH).
Traffic Channels (for user plane information)
Common Traffic Channel (CTCH) A point-to-multipoint unidirectional channel for transfer of dedicated user information (all or specified Ues).
Dedicated Traffic Channel (DTCH) A point-to-point channel, dedicated to one UE, for the transfer of user information (both up and downlink).
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
L3 Radio Resource Control (RRC)
Establishment, maintenance and release of Radio Bearers (RB) for control and user data
Establishment, maintenance and release of related radio resources between UE and UTRAN
L2 Packet Data Convergence Protocol (PDCP)
IP header compression
L2 Radio Link Control (RLC)
Segmentation and re-transmission services for both control and user data
L2 Media Access Control (MAC)
Mapping of Logical channels to Transport channels
Transport Format and Transport Format Combination selection
Execution of switching between common and dedicated transport ch.
L3
control
control
control
control
Logical
Channels
Transport
Channels
PHY
L2/MAC
L1
RLC
L2/RLC
MAC
RLC
RLC
RLC
RLC
RLC
RLC
RLC
BMC
L2/BMC
RRC
Control
PDCP
PDCP
L2/PDCP
Physical
Channels
RNC
RBS
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
RRC STATES AND CHANNEL SWITCHING
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Cell DCH
Idle mode
Cell FACH
Cell PCH
URA PCH
No radio Connection: UE location known only by the CN, location info is stored in the network based on the latest Mobility management activity the UE has performed with the UE.
Radio Connection over common channels: Location of UE is known in accuracy of a cell. This info is updated via cell update procedure. Used when Low bit rate data to be transferred between the UTRAN and UE.
Radio Connection over DCHs: The location of the UE is known on a cell level. Connection requiring highest QoS class the UTRAN and UE perform handovers. Connections requiring lower QoS class (web surfing) UE will use Cell Updates to detail its location.
Radio Connection in PCH state: UE in Cell FACH or Cell DCH but No data to be transferred. UE monitors paging occasions based on the defined discontinuous reception (DRX) cycles and hence hear the paging channel. Location of UE is known to a single cell (home cell)
Radio Connection in URA PCH state: UE in Cell FACH or Cell DCH but no considerable data to be transferred or the UE mobility is high. Avoid periodical cell update and to release the dedicated radio resources. Location of UE is known only at the URA level, to get cell level location accuracy the UE must be paged by RNC. Uses URA update.
Idle Mode: UE Switched on, no connection to network, but listens - does cell search etc (ready BCCH)
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
RNC Concepts – Transport Channel Types
CELL_FACH RRC State (Only valid for single PS Interactive RAB)
RACH – Random Access Channel (uplink only)
FACH – Forward Access Channel (downlink only)
Signalling Radio Bearers and PS RAB use cell common channels (RACH/FACH)
CELL_DCH RRC State (Valid for all RAB configurations)
DCH – Dedicated Channel (uplink or downlink)
HS-DSCH – High Speed Downlink Shared Channel (downlink only)
E-DCH – Enhanced Dedicated Channel (uplink only)
Signalling Radio Bearers and configured RABs use dedicated channels via radio links configured in each cell
Combinations include RACH/FACH, DCH/DCH, DCH/HS-DSCH and E-DCH/HS-DSCH
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
RNC Concepts – Channel Switching
Channel Switching: Reconfigure Transport Channel Type or change DCH. Applies to PS Interactive RABs (QoS class Interactive or Background).
The transport channel type can be reconfigured between using the RACH/FACH in CELL_FACH and using DCH, E-DCH or HS-DSCH in CELL_DCH. The combinations supported for uplink/downlink are:
RACH/FACH
DCH/DCH
DCH/HS-DSCH
E-DCH/HS-DSCH.
For connections using DCH, the rate can be reconfigured and this is also channel switch, e.g. 64kbps/64kbps to 64kbps/128kbps or 64kbps/HS-DSCH to 384kbps/HS-DSCH.
Note that an existing PS Streaming RAB may be reconfigured when establishing or releasing another RAB, although this is not considered ‘channel switching’.
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
TRANSITIONS FROM COM TO DED, DED TO COM ETC.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
COM to DED is a reconfiguration from CELL_FACH to CELL_DCH
Triggered by RAB Establishment, Release or Channel Switch
DED to COM is a reconfiguration from CELL_DCH to CELL_FACH
Triggered by a RAB Establishment, Release or Channel Switch
DED to DED is a reconfiguration in CELL_DCH
Triggered by a RAB Establishment, Release or Channel Switch
Note that CELL_FACH is only valid for a single PS Interactive RAB
RNC Concepts – Transition from COM to DED, DED to COM etc.
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
UeRc, Connection Properties and Connection Capabilities
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Each UeRc instance models a specific Radio Connection Configuration
A Radio Connection Configuration is a UE configuration including UTRAN-UE signalling connection and optionally one or more Radio Access Bearers (RAB)
Each RAB combination is supported via a specific UeRc instance:
UeRc 1: SRB only
UeRc 4: PS Interactive on RACH/FACH
UeRc 5: PS Interactive on DCH 64/64
UeRc 6: PS Interactive on DCH 64/128
UeRc 7: PS Interactive on DCH 64/384



...
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
UeRcRb (models Radio Bearer parameters including RLC)
UeRcRbRlc (models alternative RLC parameters for EL2, EUL 2ms TTI)
UeRcTrCh (models Dedicated Transport Channel parameters, e.g. TFS, TTI)
UeRcPhyChUl (models uplink Physical Channel Parameters, e.g. SF, Slot Format)
UeRcPhyChDl (models downlink Physical Channel Parameters, e.g. SF, Slot Format)
UeRcRab (models RAB parameters)
UeRcHsdsch (models HS-DSCH priority queue parameters)
UeRcEdchFlow (models E-DCH Mac-d flow parameters)
UeRcPhyChEdch (models E-DPDCH and E-DPCCH parameters)
UeRcEdchGainFactors (models E-DPDCH gain factors parameters)
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RNC concepts – UeRc transition
A UeRc transition describes a UE reconfiguration from one UE combination to another, e.g.
UeRc 1 -> UeRc 5 (SRB to PS Interactive 64/64)
UeRc 5 -> UeRc 10 (PS Int 64/64 to Speech + PS Int 64/64)
A UeRc transition involves a reconfiguration of RBS/DRNC (NBAP, RNSAP), DcSP (SP Bag) and UE (RRC) via a UEH procedure capsule
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RNC concepts – Connection Properties
Connection property is a concept introduced in addition to UeRc to describe a UE Radio Connection Configuration
UE configuration is function of UeRc instance + Connection Properties
Allows multiple configurations (alternative L1 and L2 parameter settings) to be supported with a single UeRc and therefore minimise the number of supported UeRc instances and UeRc transitions
Applies where the RAB combination is described by one UeRc but specific sub-characteristics are described by connection properties, e.g. EUL/HS evolved HS concepts providing higher bitrates
Connection properties include:
Enhanced Layer 2 (serving cell set property)
64QAM (serving cell set property)
MIMO (serving cell set property)
SRB on EUL (active set property)
SRB on HS (serving cell set property)
MultiCarrier (serving cell set property)
AMR Multimode (cell independent property)
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Connection capabilities map to connection properties as follows:
Connection capabilities describe the alternative configurations potentially supported by a specific UeRc instance
Connection properties describe the actual connection capabilities which are currently active for the currently configured UeRc instance for a specific UE connection
Connection capabilities can be enabled/disabled per UeRc via attribute UeRc.connectionCapability. Currently only the following are configurable
Fractional DPCH (required for SRB on HS)
MultiCarrier
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
TRANSPORT BEARERS
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
Transport Bearers are bearers in the Transport Network used to transfer control plane and user plane data between RNC and the RBS, between the UMTS Core Network (Non Access Stratum) and the RNC and between Serving RNC and Drift RNC.
A UTRAN may consist of multiple RNC and RBS (also called Node B). Transport Bearers support IP or ATM transport.
Transport bearer establishment, release and fault handling is provided by the DRH subsystem in RNC, but only for dedicated transport bearers for UEs. UEH uses this DRH service via the signal interface DrhIfTrBrP. DRH uses the Cello Packet Platform (CPP) to execute the requests from UEH to establish or release transport bearers and to inform UEH of faults reported from CPP.
Transport bearers are established by UEH on Iu interface for CS RABs and on Iub/Iur interface when not in CELL_FACH
RNC Concepts - Transport Bearers
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
Each interface (Iu to CN, Iur to DRNC and Iub to RBS) can support the following transport layer technologies:
Iu and Iur interface: ATM or IP
Iub interface – user plane: ATM, IP or both (dual stack)
Iub interface – control plane: ATM or IP
ATM transport connections are established directly from the SRNC to the RBS
DRNC is not involved in transport bearer configuration where both Iur (SRNC-DRNC link) and Iub (DRNC-RBS link) are configured for ATM
DRNC is involved in transport bearer configuration where either Iur (SRNC-DRNC link) or Iub (DRNC-RBS link) are configured for IP
RNC Concepts – IP and ATM Transport Bearers
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
The principles and rules for configuring transport bearers for different services on the Iu, Iur and Iub interface are documented in the attached document:
RNC Concepts – IP and ATM Transport Bearers
The relationship between transport bearers and RB Type is described at: http://wiki.eei.ericsson.se:8080/index.php/UEH:UehBehaviourBaseSsL_Information
2
No.
EEIDFRL
Approved
Checked
Date
Rev
Reference
Abstract
This document provides information on how to determine the number of transport bearers that shall be established or released at reconfiguration to a specific UeRc and at soft handover, hard handover and HS cell change.
1 Rules to determine the number of transport bearer connections
Transport bearer connections (IP or ATM) are established for radio rearers between the DcSP in the RNC and the RBS (Iub interface where ATM transport option applies on Iur and Iub) or the DRNC (Iur interface where different transport options apply on Iur and Iub or IP transport applies on both Iur and Iub) and also between the DcSP and the CS-CN for circuit switched Radio Access Bearers. Currently only ATM transport bearers are supported between the RNC and the CS-CN.
Transport bearer connections only apply to UE in RRC state CELL_DCH. At transition from idle or CELL_FACH to CELL_DCH all required transport bearers shall be established. At transition from CELL_DCH to idle or to CELL_FACH all established transport bearers shall be released.
Signalling Radio Bearers (SRBs)
At RRC Signalling Connection Establishment, a single transport bearer is established to support up to four signaling radio bearers SRB 1-4. Even though the SRB data rate may change (13.6 kbps standalone to 3.4 kbps in combination with Radio Access Bearers), the transport bearer for SRBs is not changed when reconfiguring between different UeRc in RRC state CELL_DCH, where both source and target UeRc are configured to have SRB uplink and downlink on DCH.
When SRB uplink and downlink have difference transport channel types, the uplink and downlink parts require separate transport bearers. Examples of such configurations are SRB on DCH/HS-DSCH, E-DCH/DCH and E-DCH/HS-DSCH.
Radio Access Bearers (RABs)
Each RAB, other than PS Interactive using FACH or HS-DSCH or multiple PS Interactive RABs on DCH, requires one unique transport bearer on the Iub or Iur interface in each RBS in the active set (multiple cells in one RBS share transport bearers). Dedicated transport bearers are not applicable in CELL_FACH as stated above.
Additionally, each circuit switched RAB requires one transport bearer on the Iu interface to the CS-CN.
PS RABs using HS-DSCH (channel type ubChTypeDchHsdsch)
A PS RAB configured on DCH/HS-DSCH (currently Streaming or Interactive RABs supported) requires one transport bearer for the downlink HS-DSCH Mac-D Flow, configured in the HS-DSCH serving cell only and one transport bearer for the uplink DCH, configured in each RBS in the active set (multiple cells in one RBS share transport bearers).
PS RABs using E-DCH and HS-DSCH (channel type ubChTypeEdchHsdsch)
A PS RAB configured on E-DCH/HS-DSCH requires one transport bearer for the downlink HS-DSCH Mac-D Flow, configured in the HS-DSCH serving cell only and one transport bearer for the uplink E-DCH Mac-D Flow, configured in each RBS in the active set (multiple cells in one RBS share transport bearers). In addition the SRBs shall be reconfigured to use the E-DCH in the uplink. Therefore, the SRBs require one transport bearer for the uplink E-DCH Mac-D Flow, configured in each RBS in the active set and one transport bearer for the downlink DCH, configured in each RBS in the active set (multiple cells in one RBS share transport bearers). The existing transport bearer, supporting SRBs on DCH in both uplink and downlink, shall be released in each RBS in the active set. Note that the uplink E-DCH shall only be configured together with downlink HS-DSCH.
Multiple PS Interactive Radio Access Bearers
Multiple PS Interactive RABs on DCH shall be multiplexed onto the same transport bearer. Therefore, multiple PS Interactive RABs on DCH require only one transport bearer configured in each RBS in the active set (multiple cells in one RBS share transport bearers).
Multiple PS Interactive RABs configured on uplink DCH and downlink HS-DSCH require only one transport bearer for the uplink DCH, configured in each RBS in the active set (multiple cells in one RBS share transport bearers) and one transport bearer for each downlink HS-DSCH Mac-D Flow, i.e. each PS Interactive RAB, configured in the HS-DSCH serving cell only.
Furthermore, the establishment or release of a second PS Interactive RAB on DCH requires that one new transport bearer is established in each RBS in the active set (multiple cells in one RBS share transport bearers) to support the two PS Interactive RABs (multiplexed onto the same transport bearer). The existing transport bearer, supporting the single PS Interactive RAB, shall be released in each RBS in the active set.
Multiple PS Interactive RABs configured on uplink E-DCH and downlink HS-DSCH require one transport bearer for each E-DCH Mac-D flow, i.e. each PS Interactive RAB, configured in each RBS in the active set (multiple cells in one RBS share transport bearers) and one transport bearer for each downlink HS-DSCH Mac-D Flow, i.e. each PS Interactive RAB, configured in the HS-DSCH serving cell only.
Reconfiguration from CELL_FACH to CELL_DCH
Transport bearers are required, in the active cell, for Signalling Radio Bearers and each configured Radio Access Bearer, according to the rules described above. This applies for all cases where the RRC state is changed from CELL_FACH to CELL_DCH, i.e. RAB establishment, RAB release and channel switching.
Rate Change for PS Interactive RABs on DCH (channel type ubChTypeDch)
At change of DCH rate for PS Interactive RABs configured on DCH in both uplink and downlink requires that one new transport bearer is established in each RBS in the active set (multiple cells in one RBS share transport bearers) to support the new rate. The existing transport bearer, supporting the old rate, shall be released in each RBS in the active set.
Note than it is not possible to reconfigure a transport bearer to support a different rate or different link characteristics. Instead, a new transport bearer is established and the old bearer is released.
Rate Change for PS Interactive RABs on DCH/HS-DSCH (channel type ubChTypeDchHsdsch)
At change of DCH rate for PS Interactive RABs configured on DCH in uplink and HS-DSCH in downlink requires that one new transport bearer is established in each RBS in the active set (multiple cells in one RBS share transport bearers) to support the new rate on the uplink DCH. The existing transport bearer, supporting the old uplink DCH rate, shall be released in each RBS in the active set. The transport bearers supporting the HS-DSCH MAC-D Flows in the HS-DSCH Serving Cell are not modified.
HS-DSCH Serving Cell Change
At change of HS-DSCH Serving Cell, a new transport bearer shall be established in the new HS-DSCH Serving Cell for each HS-DSCH Mac-D Flow, i.e. each PS RAB. The existing transport bearer for each HS-DSCH Mac-D Flow in the old HS-DSCH Serving Cell shall be released.
Soft Handover
At Radio Link Deletion, where no other cell in that RBS is in the active set, all transport bearers to the RBS for the removed cell shall be released. If one or more cells in the active set have the same RBS then no transport bearers shall be removed.
At Radio Link Addition where there is already a cell in the same RBS configured in the active set, i.e. the same Radio Link Set, no transport bearers shall be established or released. At Radio Link Addition where no other cell in that RBS is already configured in the active set, a transport bearer shall be established towards the new RBS, corresponding to each existing transport bearer configured to existing RBSs in the active set, with the exception of transport bearers supporting HS-DSCH Mac-D Flows, which only apply to the HS-DSCH Serving Cell.
Hard Handover
At hard handover, a transport bearer shall be established towards the new RBS, corresponding to each existing transport bearer configured to existing RBSs in the active set. All existing transport bearers shall be released.
At inter frequency handover (IFHO) of a connection using HS-DSCH, a HS-DSCH Serving Cell Change to the target cell is performed. Therefore, a new transport bearer shall be established in the new HS-DSCH Serving Cell, i.e. the target cell, for each HS-DSCH Mac-D Flow, i.e. each PS RAB.
Incoming SRNC Relocation or Handover from GSM
One transport bearer is required, in the active cell, for Signalling Radio Bearers.
Additionally, if a circuit switched Radio Access Bearer is to be configured, one transport bearer is required on the Iub interface between the DcSP and the RBS supporting the active cell and another transport bearer is required on the Iu between the DcSP and the CS-CN.
2 Example Configurations
Included below are some example configurations and corresponding transport bearer connections:
Standalone SRB on DCH/DCH, 3 cells (in different RBS)
· One connection for all SRBs in each cell (3 connections in total)
Standalone SRB on DCH/HS-DSCH, 3 cells (in different RBS)
· One connection for all SRBs on uplink DCH in each cell (3 connections in total)
· One connection for all SRBs on downlink HS-DSCH in HS-DSCH serving cell (1 connection in total)
Standalone SRB on E-DCH/HS-DSCH, 3 cells (in different RBS)
· One connection for all SRBs on uplink E-DCH in each cell (3 connections in total)
· One connection for all SRBs on downlink HS-DSCH in HS-DSCH serving cell (1 connection in total)
Speech + PS Interactive on DCH, 3 cells (in different RBS)
· One connection for all SRBs in each cell (3 connections in total)
· One connection for all Speech Radio Bearers in each cell (3 connections in total)
· One connection for Speech RAB to CS-CN (1 connection in total)
· One connection for single PS Interactive Radio Bearer in each cell (3 connections in total)
Speech + 2xPS Interactive on DCH, 3 cells (in different RBS)
· One connection for all SRBs in each cell (3 connections in total)
· One connection for all Speech Radio Bearers in each cell (3 connections in total)
· One connection for Speech RAB to CS-CN (1 connection in total)
· One connection for both PS Interactive Radio Bearers in each cell (3 connections in total)
PS Interactive on DCH/HS-DSCH, 3 cells (in different RBS)
· One connection for all SRBs in each cell (3 connections in total)
· One connection for PS Interactive Radio Bearer downlink on HS-DSCH in HS-DSCH Serving Cell (1 connection in total)
· One connection for PS Interactive Radio Bearer uplink on DCH in each cell (3 connections in total)
PS Interactive on E-DCH/HS-DSCH, 3 cells (in different RBS)
· One connection for all SRBs downlink on DCH in each cell (3 connections in total)
· One connection for all SRBs uplink on E-DCH in each cell (3 connections in total)
· One connection for PS Interactive Radio Bearer downlink on HS-DSCH in HS-DSCH Serving Cell (1 connection in total)
· One connection for PS Interactive Radio Bearer uplink on E-DCH in each cell (3 connections in total)
2xPS Interactive on DCH/HS-DSCH, 3 cells (in different RBS)
· One connection for all SRBs in each cell (3 connections in total)
· One connection for first PS Interactive Radio Bearer downlink on HS-DSCH in HS-DSCH Serving Cell (1 connection in total)
· One connection for second PS Interactive Radio Bearer downlink on HS-DSCH in HS-DSCH Serving Cell (1 connection in total)
· One connection for both PS Interactive Radio Bearers uplink on DCH in each cell (3 connections in total)
2xPS Interactive on E-DCH/HS-DSCH, 3 cells (in different RBS)
· One connection for all SRBs downlink on DCH in each cell (3 connections in total)
· One connection for all SRBs uplink on E-DCH in each cell (3 connections in total)
· One connection for first PS Interactive Radio Bearer downlink on HS-DSCH in HS-DSCH Serving Cell (1 connection in total)
· One connection for second PS Interactive Radio Bearer downlink on HS-DSCH in HS-DSCH Serving Cell (1 connection in total)
· One connection for first PS Interactive Radio Bearer uplink on E-DCH in each cell (3 connections in total)
· One connection for second PS Interactive Radio Bearer uplink on E-DCH in each cell (3 connections in total)
IFHO of Speech + 3xPS Interactive on DCH/HS-DSCH, 3 source cells (in different RBS)
To establish:
· One connection for all SRBs in target cell (1 connection in total)
· One connection for first PS Interactive Radio Bearer downlink on HS-DSCH in target HS-DSCH Serving Cell (1 connection in total)
· One connection for second PS Interactive Radio Bearer downlink on HS-DSCH in target HS-DSCH Serving Cell (1 connection in total)
· One connection for third PS Interactive Radio Bearer downlink on HS-DSCH in target HS-DSCH Serving Cell (1 connection in total)
· One connection for three PS Interactive Radio Bearers uplink on DCH in target cell (1 connection in total)
· One connection for all Speech Radio Bearers in target cell (1 connection in total)
To release:
· One connection for all SRBs in each source cell (3 connections in total)
· One connection for first PS Interactive Radio Bearer downlink on HS-DSCH in source HS-DSCH Serving Cell (1 connection in total)
· One connection for second PS Interactive Radio Bearer downlink on HS-DSCH in source HS-DSCH Serving Cell (1 connection in total)
· One connection for third PS Interactive Radio Bearer downlink on HS-DSCH in source HS-DSCH Serving Cell (1 connection in total)
· One connection for three PS Interactive Radio Bearers uplink on DCH in each source cell (3 connections in total)
· One connection for all Speech Radio Bearers in each source cell (3 connections in total)
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Macro diversity: Three radio links served by two RBSes.
RRC
AAL2
DCH FP
General Radio access bearers and signaling connections, established between a UE and the different CN domains, have two well differentiated components inside the WCDMA RAN: the Iu part (CN - RNC) and the radio part (UE - RNC). The RNC handles the two components separately, but coordinates them in a way that logically resembles UE - CN connections.
On a high level description, the steps to set up or release a call between a UE and a CN domain through the WCDMA RAN are fairly independent on whether the call is UE originated or UE terminated. Call establishment is always initiated by events occurring at NAS (Non Access Strata) level. As a result of either a user request to establish a call (UE originated call) or a paging procedure (UE terminated call), the NAS functions in the UE establish a signaling connection to the appropriate CN domain. This signaling connection relies on AS connectivity through the WCDMA-RAN. To provide AS connectivity, the AS functions in the UE will first request the RNC to establish an RRC connection; unless one existed beforehand, in which case the existing one is used. If a new RRC connection is established, supervision of its radio connection is started immediately. 1 RRC connection = 4 SRB each with its own RLC instance with its own DCCH logical channel. MAC multiplex this into 1 common (FACH/RACH) or 1 dedicated (DCH) transport channel.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Protocols over the Iu, Iub and Uu interface - Control Plane
UEH
DRH
CCS
PDR
RNH
DCS
RANAP
Iu-FP
GTP-U/UDP-IP
/LLC/SNAP
Iu-c-FP
PCH-FP/RACH-FP
/FACH-FP
DCH-FP
RRC
NBAP
RRC
RLC
MAC-D
RLC
MAC-C
UE
PCH-FP/RACH-FP/FACH-FP or DCH-FP
MAC-C or MAC-D
RLC and RRC
Step 1: Shows the Iu plane Control signaling messages, described in the RANAP protocol (control signaling from CN to RNC and from RNC to CN). RNH handles sending and receiving of these messages, although UEH terminates dedicated RANAP messages they have to be routed through the RNH.
Step 2: The RANAP messages received may lead to RRC messages that need to be relayed top the UE, e.g.. the RANAP message RAB ASSIGNMENT RERQUEST received will lead to an RRC message RADIO BEARER SETUP.
Step 3: The RRC messages (dedicated messages) are sent from UEH through DRH to DCS where they are routed through the same path as the user data described previously. For RRC messages from the UE they are simply the reverse.
Step 4: The Global RRC messages are sent from RNH.
Step 5: They are routed to CCS via DRH and then sent on to the UE as described previously for user data. For RRC messages from the UE they are simply the reverse.
Step 6: Noting that dedicated RRC messages are routed via the MAC-D/MAC-C interface if the UE is on a common channel
Step 7: The control signaling interface over the Iub between the RNC and the Node B uses the NBAP protocol.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Protocols over the Iu, Iub and Uu interface - User Plane
UEH
DRH
CCS
RNH
DCS
RANAP
Iu-c-FP
PCH-FP/RACH-FP
/FACH-FP
DCH-FP
RRC
NBAP
RRC
RLC
MAC-D
RLC
MAC-C
UE
PCH-FP/RACH-FP/FACH-FP or DCH-FP
MAC-C or MAC-D
RLC and RRC
Step 1: Depicts the Iu User plane flow from a PS CN to the RNC, PS user data is received in AAL5 format.
Step 2: Depicts the user plane flow link between PDR and DCS, when user data is passing through the RNC from the CN it must be routed from PDR to DCS where the MAC-D and FP must be applied. Similarly if data is flowing from the UE to the CN the DCS must apply the DCH FP and MAC-D before PDR can apply its protocols before the data can be sent in a usable format to the CN.
Step 3: Depicts the Iu User plane flow from a CS CN to the RNC, CS user data is received in AAL2 format.
Step 4: Depicts the user plane flow link between Iu FP and the protocols to be applied to data sent/received from the UE, when user data is passing through the RNC from the CN it must be subject to Iu-c-FP before the MAC-D and FP can be applied. Similarly if data is flowing from the UE to the CN the DCS must apply the DCH FP and MAC-D before Iu-c-FP can be applied and the data sent in a usable format to the CN.
Step 5: Depicts the Iub and Uu interfaces and protocols applied to these interfaces for user data transferred on dedicated channels. The data received from the CN has passed through to the MAC-D of DCS where scheduling and mapping to transport channels is performed, the DCH FP is applied and the data sent through cello to the Node B via the Iub interface. In the Node B the ATM and DCH FP are applied and the transport channel mapped to a physical channel. The data is then sent to the UE where the MAC-D and RLC protocols are applied (Uu). The flow from the UE to the RNC is just the reverse. It should now be possible to see the Flow of user data from the CN to the RNC and from the RNC to the Node B and to UE beyond (e.g. for CS steps 3, 4 and 5, for PS clicks 1, 2 and 5)
Step 6: If the user is on a common channel then the data from the CN is routed from the MAC-d to the MAC-C where multiplexing etc is performed for the common channel. The logical channel is already assigned so the data must go from MAC-D to MAC-C.
Step 7: This depicts the flow of user data where the user is on a common channel, the received/sent user data is routed across the mac-d to mac-c link. The user data flows from the RNC to the UE across the MAC-D to MAC-C connection where multiplexing is performed and the FACH FP is applied before the data is sent on the the UE over the Iub (ATM and FP protocols applicable) and then Uu interface (MAC-C and RLC protocols applicable). It should now be possible to see the Flow of user data from the CN to the UE . For data flowing in the opposite direction (UE to CN) the flow is simply the reverse where the MAC-C demultiplexes the data before it is sent to the MAC-D for analysis and then on to the CN as shown.
Slide title In CAPITALS 50 pt Slide subtitle 32 pt
MOBILITY
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Summed signal
RNC Concepts - Micro Diversity
Microdiversity means the situation where the propagating multipath components are combined in the BS as shown above. The WCDMA utilises multipath propagation. This means that the BS RAKE receiver is able to determine, differentiate and sum up several signals received from the radio path. In reality, a signal sent to the radio path is reflected from the ground, water, buildings etc and at the receiving end the sent signal can be ‘seen’ as many copies, all of then coming to the receiver at slightly different phase and time.The microdiverstity function at BS level combines different signal paths received from one cell, and in the case of sectored BS, the outcome from different sectors, which is also referred to as softerhandover.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RNC Concepts - Macro Diversity
Because of the fact that the UE may use cells belonging to different BS’s or even different RNC’s the macrodiversity functionality also exists on RNC level. There is no RAKE receiver in the RNC so summing is done by different methods.
In the diagram above, the BS’s firstly sum up the signal concerning the radio paths of their own and final summing of the data stream is done on the RNC level (by the diversity handler equipment -DHO)
To gain better subjective call quality multipath propagation is used, I.e the idea is that quality will be better when the final signal is constructed from several sources (multipath).
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Multipath signal
f1
Frequency
f1
Frequency
f1
RNC
RNC
Iur
If a new connection is established before the old connection is released then the handover is called soft handover.
Soft handover is performed between two cells belonging to different Node B’s but not necessarily the same RNC. In any case the RNC involved in the soft handover must coordinate the execution of the soft handover over the Iur interface. In a soft handover event the source and target cells have the same frequency.
A softer handover is a handover by which a new signal is either added to or deleted from the active set, or replaced by a stronger signal within the different sectors, which are under the same Node B.
In sifter handover the Node B transmits through one sector but receives from more than one sector.
When soft and softer handovers occur simultaneously the term soft-softer handover is used. A soft softer handover may occur, for instance, in association with inter-RNC handover while an inter sector signal is added to the UE’s active set along with adding a new signal via another cell controlled by an RNC.
The main difference to note between soft and softer is that in soft the signals are sent up to the RNC for combining while with softer handover the combining is done by the Node B.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
Frequency
f1
Frequency
f2
Frequency
f1
Frequency
f1
Iur
RNC
RNC
During the handover process, if the old connection is released before making the new connection it is called a hard handover (involving a short cut in the connection)
Inter-Frequency - the carrier frequency of the new radio access is different
Intra-Frequency - the carrier frequency of new and old are the same.
In the diagram on the right, the neighbouring RNC is not connected by Iur interface due to radio network planning strategy or transmission reasons and hence the inter-RNC soft handover is not possible. In fact this is an inter RNC handover involving the MSC.
Generally the frequency reuse factor is one for WCDMA, meaning all Node B transmit on the same frequency and also all UE share a common frequency within the network.
Inter frequency handover can also occur in Hierarchical Cell Structure network between the separate layers
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5 20 pt
2008-03-11
RNC
WCDMA
GSM
BTS
Cell Change PS
The Inter-system handover/cell change can be applied in areas where WCDMA and GSM/GPRS systems co-exist. Inter-system handover/cell change (Known as IRAT - Inter Radio Access technology) is required to complement areas of each other in order to ensure continuity of services. The IRAT functions can also be used to control the load between the systems, when the coverage area of the two systems overlap with each other. The RNC recognises the possibility of IRAT handover/cell change mainly based on the neighbour cell definitions and other control parameters.
One difference between Inter RAT handover and Inter RAT Cell Change is that in the IRATCC case there are no resources reserved in the target cell beforehand
TE
MT
RAN
CN
EDGE
NODE
CN
Gateway
TE
UMTS
End