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
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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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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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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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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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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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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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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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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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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.
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Slide title 40 pt Slide subtitle 24 pt Text 24 pt Bullets level 2-5
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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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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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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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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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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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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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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)
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
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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Best practice for example.
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)
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
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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Best practice for example.
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
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
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
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
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