1CN Core Network
UE User Equipment
Service manager layer
Service convergence layer
Radio access layer
Common Protocol Model of UTRAN Interfaces
The principle of interface protocol architecture is the logical
mutual-independence between layers and planes. Protocol layers of a
specified protocol version, or even all layers in a plane can be
modified if required in the future.
Protocols of the terrestrial interfaces follow a general protocol
model, based on the principle that the layers and planes of the
protocols are logically independent of each other. So, the radio
network layer and the transport network layer are independent of
each other and the control plane and the user plane are independent
of each other. Therefore, the protocol stacks and planes can be
easily altered as and when required to fit future
requirements.
9.unknown
UMTS Rel99:
WCDMA L1
RRC :Radio Resource Control
Chapter 2 UTRAN Interface Protocol and Functions
*
Iu Interface
Iur Interface
Iub Interface
Uu Interface
1,Physical Layer:
The physical layer provides transport channels for ATM cells. It
adds transport overheads to the ATM cells from the upper ATM layer
to form consecutive bit stream. It also extracts the valid ATM
cells from the consecutive bit stream received from the physical
media and transports them to the ATM layer.
The physical layer comprises two sublayers: Transmission
Convergence (TC) sublayer and Physical Media (PM) sublayer.
2,ATM Layer:
Asynchronous Transfer Mode (ATM) layer is above the physical layer
and communicates with its peer layer by utilizing services provided
by the physical layer. The communication unit is cell. The ATM
layer is independent of the type of the physical medium, the actual
implementation of the physical layer and the type of the services
transported. It only identifies and processes cell headers. That is
to say, the ATM layer inserts a 5-byte header to the 48-byte cell
payload transported from its upper layer, or removes the header
from the cells transported from the physical layer and transports
it to the upper layer.
3,AAL2:
AAL2 focuses on VBR (low rate) services with specific timing
requirements, for example, compression voice service. In this kind
of services, the data packets generated are too small to fill a
cell, but to wait for enough data packets to fill the cell will
surely lead to great delay. Therefore, AAL protocol multiplexes
multiple users in one ATM channel, i.e., it fills a cell with the
data packets from multiple users and adds a header to each packet
to indicate which user it comes from.
4,AAL5:
AAL5 protocol is an AAL protocol especially made for Category-C
connection oriented services for the purpose of efficiency
improvement on the basis of AAl3/4. AAL5 protocol includes two
sublayers: Segment And Reassemble (SAR) and Common part Convergence
Sublayer (CPCS). The Segment And Reassemble (SAR) sublayer in the
AAL5 segments the CPCS-PDU into 48-byte SAR-PDU without any
overheads. Reassembly function is achieved during PDU
receiving.
5,SSCOP:
6,SSCF:
The SSCF functions as the adaptation layer of the SSCOP and the
upper layer applications. Upper layer applications refer to NBAP,
MTP3-B and Signal Transporter (STC). The MTP3-B is used for NNI,
which has higher link quality. SAAL is required to support link
quality check and to help the MTP3-B with link switchover. But,
NBAP is used for User Network Interface (UNI), which has poorer
link quality and greater delay. Therefore, SSCF is divided into
SSCF-NNI and SSCF-UNI to cater to different upper layer
applications.
7,MTP3-B:
Based on Message Transfer Part Layer 3 (MTP3), MTP3-B is the
protocol specification aiming at ATM features. As the signaling
transport layer, MTP3-B is responsible for transferring signaling
messages, managing signaling networks and signaling links. It
performs message exchange via the services provided by SAAL.
8,ALCAP:
Access Link Control Application Part (ALCAP), also called Q.AAL2
protocol, complies with ITU-T Q.2630.1 and resides in the user
plane of the Iub/Iur/Iu-CS transport network layer with the
signaling bearers of SAAL UNI type and MTP3-B type. ALCAP consists
of a Q.AAL2 protocol processing layer (one plane) and two STC
adaptation layers (the other plane) in which the former plane
performs all protocol functions while the latter one adapts
primitives and shield bottom-layer differences (SAAL,
MTP3-B).
The basic function of ALCAP is establishing and releasing AAL2
connection between two SPs. Besides, it also maintains and manages
such resources as path, tunnel in the micro cell of the signaling
system. The AAL2 connections controlled by ALCAP shall be regarded
as the transmission bearer for the control plane and user plane of
the radio network layer.
9,SCCP:
*
1,Iu-PS Data Bearer:
The structure of Iu-PS user-plane data bearer is shown in slide.
Working in IP over ATM (IPoA) bearing mode, the AAL layer takes
AAL5 as the ATM adaptation type.
2,IP:
Internet Protocol (IP) provides a globally unified addressing mode
to shield the differences between physically network addresses,
thus enabling route search. Besides, it also provides a globally
unified packet format to shield the differences between network
link layers, thus enabling network interconnection.
3,UDP:
Providing connectionless service, User Datagram Protocol (UDP)
increases port addresses based on IP to distinguish different
applications on a host. For example, the destination port number
used by GTP-U is 2152 and the source port number is an arbitrary
value distributed by the transmitting end.
4,GTP-U
*
*
Physical (Full Rate E1 or STM1 Optical)
ATM Lower Layers
*
Radio Access BearerRABManagement
Establishment, Modification and Release of RAB
Iu data transmission
normal data transmission
abnormal data transmission
*
Iu Signaling Trace Management
Iu Interface Abnormality Management
CBS(Cell Broadcast Service) Control
Iu Interface
Iur Interface
Iub Interface
Uu Interface
1,Physical Layer:
The physical layer provides transport channels for ATM cells. It
adds transport overheads to the ATM cells from the upper ATM layer
to form consecutive bit stream. It also extracts the valid ATM
cells from the consecutive bit stream received from the physical
media and transports them to the ATM layer.
The physical layer comprises two sublayers: Transmission
Convergence (TC) sublayer and Physical Media (PM) sublayer.
2,ATM Layer:
Asynchronous Transfer Mode (ATM) layer is above the physical layer
and communicates with its peer layer by utilizing services provided
by the physical layer. The communication unit is cell. The ATM
layer is independent of the type of the physical medium, the actual
implementation of the physical layer and the type of the services
transported. It only identifies and processes cell headers. That is
to say, the ATM layer inserts a 5-byte header to the 48-byte cell
payload transported from its upper layer, or removes the header
from the cells transported from the physical layer and transports
it to the upper layer.
3,AAL2:
AAL2 focuses on VBR (low rate) services with specific timing
requirements, for example, compression voice service. In this kind
of services, the data packets generated are too small to fill a
cell, but to wait for enough data packets to fill the cell will
surely lead to great delay. Therefore, AAL protocol multiplexes
multiple users in one ATM channel, i.e., it fills a cell with the
data packets from multiple users and adds a header to each packet
to indicate which user it comes from.
4,AAL5:
AAL5 protocol is an AAL protocol especially made for Category-C
connection oriented services for the purpose of efficiency
improvement on the basis of AAl3/4. AAL5 protocol includes two
sublayers: Segment And Reassemble (SAR) and Common part Convergence
Sublayer (CPCS). The Segment And Reassemble (SAR) sublayer in the
AAL5 segments the CPCS-PDU into 48-byte SAR-PDU without any
overheads. Reassembly function is achieved during PDU
receiving.
5,SSCOP:
6,SSCF:
The SSCF functions as the adaptation layer of the SSCOP and the
upper layer applications. Upper layer applications refer to NBAP,
MTP3-B and Signal Transporter (STC). The MTP3-B is used for NNI,
which has higher link quality. SAAL is required to support link
quality check and to help the MTP3-B with link switchover. But,
NBAP is used for User Network Interface (UNI), which has poorer
link quality and greater delay. Therefore, SSCF is divided into
SSCF-NNI and SSCF-UNI to cater to different upper layer
applications.
7,MTP3-B:
Based on Message Transfer Part Layer 3 (MTP3), MTP3-B is the
protocol specification aiming at ATM features. As the signaling
transport layer, MTP3-B is responsible for transferring signaling
messages, managing signaling networks and signaling links. It
performs message exchange via the services provided by SAAL.
8,ALCAP:
Access Link Control Application Part (ALCAP), also called Q.AAL2
protocol, complies with ITU-T Q.2630.1 and resides in the user
plane of the Iub/Iur/Iu-CS transport network layer with the
signaling bearers of SAAL UNI type and MTP3-B type. ALCAP consists
of a Q.AAL2 protocol processing layer (one plane) and two STC
adaptation layers (the other plane) in which the former plane
performs all protocol functions while the latter one adapts
primitives and shield bottom-layer differences (SAAL,
MTP3-B).
The basic function of ALCAP is establishing and releasing AAL2
connection between two SPs. Besides, it also maintains and manages
such resources as path, tunnel in the micro cell of the signaling
system. The AAL2 connections controlled by ALCAP shall be regarded
as the transmission bearer for the control plane and user plane of
the radio network layer.
9,SCCP:
*
Physical (Full Rate E1 or STM1 Optical)
ATM Lower Layers
*
Support SRNC relocation
Paging between RNCs
Protocol Error Report
Dedicated Channel Functions
Establish, Modify or Release Dedicated Channels in DRNC during
handover
Transmission of DCH TB(Transmission Block) on Iur
Management of RL(Radio Link) in DRNS by Dedicated Measurement
Procedure and Filter Control
RL ManagementCompressed Mode Management
In order to support soft handover between RNCs, Iur interface was
introduced. With the development of the standard, more functions
are introduces.
1.Support basic mobility functions between RNCs;
2.Support dedicated channel services;
3.Support common channel services;
4.Support global resource management.
Iur Interface Functions
Common Channel Functions
Establishment, Deletion of Common transport Channels on
IurOccupation of Common Transport Channels for Transmit UE
information which is in Common Channel state in DRNC
Separate MAC-d From MAC-c
Global Resource Management
*
Iu Interface
Iur Interface
Iub Interface
Uu Interface
12.unknown
1,Physical Layer:
The physical layer provides transport channels for ATM cells. It
adds transport overheads to the ATM cells from the upper ATM layer
to form consecutive bit stream. It also extracts the valid ATM
cells from the consecutive bit stream received from the physical
media and transports them to the ATM layer.
The physical layer comprises two sublayers: Transmission
Convergence (TC) sublayer and Physical Media (PM) sublayer.
2,ATM Layer:
Asynchronous Transfer Mode (ATM) layer is above the physical layer
and communicates with its peer layer by utilizing services provided
by the physical layer. The communication unit is cell. The ATM
layer is independent of the type of the physical medium, the actual
implementation of the physical layer and the type of the services
transported. It only identifies and processes cell headers. That is
to say, the ATM layer inserts a 5-byte header to the 48-byte cell
payload transported from its upper layer, or removes the header
from the cells transported from the physical layer and transports
it to the upper layer.
3,AAL2:
AAL2 focuses on VBR (low rate) services with specific timing
requirements, for example, compression voice service. In this kind
of services, the data packets generated are too small to fill a
cell, but to wait for enough data packets to fill the cell will
surely lead to great delay. Therefore, AAL protocol multiplexes
multiple users in one ATM channel, i.e., it fills a cell with the
data packets from multiple users and adds a header to each packet
to indicate which user it comes from.
4,AAL5:
AAL5 protocol is an AAL protocol especially made for Category-C
connection oriented services for the purpose of efficiency
improvement on the basis of AAl3/4. AAL5 protocol includes two
sublayers: Segment And Reassemble (SAR) and Common part Convergence
Sublayer (CPCS). The Segment And Reassemble (SAR) sublayer in the
AAL5 segments the CPCS-PDU into 48-byte SAR-PDU without any
overheads. Reassembly function is achieved during PDU
receiving.
5,SSCOP:
6,SSCF:
The SSCF functions as the adaptation layer of the SSCOP and the
upper layer applications. Upper layer applications refer to NBAP,
MTP3-B and Signal Transporter (STC). The MTP3-B is used for NNI,
which has higher link quality. SAAL is required to support link
quality check and to help the MTP3-B with link switchover. But,
NBAP is used for User Network Interface (UNI), which has poorer
link quality and greater delay. Therefore, SSCF is divided into
SSCF-NNI and SSCF-UNI to cater to different upper layer
applications.
7,ALCAP:
Access Link Control Application Part (ALCAP), also called Q.AAL2
protocol, complies with ITU-T Q.2630.1 and resides in the user
plane of the Iub/Iur/Iu-CS transport network layer with the
signaling bearers of SAAL UNI type and MTP3-B type. ALCAP consists
of a Q.AAL2 protocol processing layer (one plane) and two STC
adaptation layers (the other plane) in which the former plane
performs all protocol functions while the latter one adapts
primitives and shield bottom-layer differences (SAAL,
MTP3-B).
The basic function of ALCAP is establishing and releasing AAL2
connection between two SPs. Besides, it also maintains and manages
such resources as path, tunnel in the micro cell of the signaling
system. The AAL2 connections controlled by ALCAP shall be regarded
as the transmission bearer for the control plane and user plane of
the radio network layer.
8,Abbreviation:
PCH FP: Paging CHannel Frame Protocol
SSCOP:Special Service Connection Protocol
DCH FP: Dedicated CHannel Frame Protocol
*
ATM Lower Layers
RRC: Radio Resource Control
RLC: Radio Link Control
MAC: Medium Access Control
Iub Common Channel Data Transmission
Logical O&M of Node Bmaintenance functions such as cell
configuration ManagementFault ManagementBlock Management,
etc.
System Information Management
Iub Dedicated Data transmission
Compressed Mode Control
Iu Interface
Iur Interface
Iub Interface
Uu Interface
Uu Interface Protocol Stack Structure
Uu interface is the interface between User Equipment (UE) and UMTS
Terrestrial Radio Access Network (UTRAN) and it is the most
important interface in the WCDMA system.
The radio interface is layered into three protocol layers:
- the physical layer (L1);
- network layer (L3).
Layer 2 is split into following sublayers: Medium Access Control
(MAC), Radio Link Control (RLC), Packet Data Convergence Protocol
(PDCP) and Broadcast/Multicast Control (BMC).
Layer 3 and RLC are divided into Control (C-) and User (U-) planes.
PDCP and BMC exist in the U-plane only.
13.unknown
Multiplexing of transport channels and de-multiplexing of encoded
composite channels
Mapping of encoded composite transport channels on physical
channels
Macro-diversity distribution/combining and soft handover
execution
Error detection on transport channels and indication to higher
layers
FEC encoding/decoding and interleaving/de-interleaving of transport
channels
Rate matching of coded transport channels to physical
channels
Power weighting and combining of physical channels
closed-loop power control
open-loop power control
*
Modulation and spreading/demodulation and de-spreading of physical
channels
Synchronization between frequency and time (chip, bit, slot,
frame)
Radio characters measurements (FER, SIR, Interference power) and
indication to higher layers
Compressed mode support
Diversity of Transmission/Receiving
*
MAC Services to upper layers
- Data transfer. This service provides unacknowledged transfer of
MAC SDUs between peer MAC entities. This service does not provide
any data segmentation. Therefore, segmentation/reassembly function
should be achieved by upper layer.
- Reallocation of radio resources and MAC parameters. This service
performs on request of RRC execution of radio resource reallocation
and change of MAC parameters, i.e. reconfiguration of MAC functions
such as change of identity of UE, change of transport format
(combination) sets, change of transport channel type. In TDD mode,
in addition, the MAC can handle resource allocation
autonomously.
*
selection of appropriate Transport Format for each Transport
Channel depending on instantaneous data rate
priority handling between data flows of one UE
priority handling between UEs by means of dynamic scheduling
identification of UEs on common transport channels
multiplexing/demultiplexing of higher layer PDUs into/from
transport blocks delivered to/from the physical layer on common
transport channels
multiplexing/demultiplexing of higher layer PDUs into/from
transport block sets delivered to/from the physical layer on
dedicated transport channels
traffic volume monitoring
ciphering for transparent RLC
The functions of MAC include:
- Mapping between logical channels and transport channels. The MAC
is responsible for mapping of logical channel(s) onto the
appropriate transport channel(s).
- Selection of appropriate Transport Format for each Transport
Channel depending on instantaneous source rate. Given the Transport
Format Combination Set assigned by RRC, MAC selects the appropriate
transport format within an assigned transport format set for each
active transport channel depending on source rate. The control of
transport formats ensures efficient use of transport
channels.
- Priority handling between data flows of one UE. When selecting
between the Transport Format Combinations in the given Transport
Format Combination Set, priorities of the data flows to be mapped
onto the corresponding Transport Channels can be taken into
account. Priorities are e.g. given by attributes of Radio Bearer
services and RLC buffer status. The priority handling is achieved
by selecting a Transport Format Combination for which high priority
data is mapped onto L1 with a "high bit rate" Transport Format, at
the same time letting lower priority data be mapped with a "low bit
rate" (could be zero bit rate) Transport Format. Transport format
selection may also take into account transmit power indication from
Layer 1.
- Priority handling between UEs by means of dynamic scheduling. In
order to utilise the spectrum resources efficiently for bursty
transfer, a dynamic scheduling function may be applied. MAC
realises priority handling on common and shared transport channels.
Note that for dedicated transport channels, the equivalent of the
dynamic scheduling function is implicitly included as part of the
reconfiguration function of the RRC sublayer.
- Identification of UEs on common transport channels. When a
particular UE is addressed on a common downlink channel, or when a
UE is using the RACH, there is a need for inband identification of
the UE. Since the MAC layer handles the access to, and multiplexing
onto, the transport channels, the identification functionality is
naturally also placed in MAC.
- Multiplexing/demultiplexing of upper layer PDUs into/from
transport blocks delivered to/from the physical layer on common
transport channels. MAC should support service multiplexing for
common transport channels, since the physical layer does not
support multiplexing of these channels.
- Multiplexing/demultiplexing of upper layer PDUs into/from
transport block sets delivered to/from the physical layer on
dedicated transport channels. The MAC allows service multiplexing
for dedicated transport channels. This function can be utilised
when several upper layer services (e.g. RLC instances) can be
mapped efficiently on the same transport channel. In this case the
identification of multiplexing is contained in the MAC protocol
control information.
- Traffic volume measurement. Measurement of traffic volume on
logical channels and reporting to RRC. Based on the reported
traffic volume information, RRC performs transport channel
switching decisions.
- Transport Channel type switching. Execution of the switching
between common and dedicated transport channels based on a
switching decision derived by RRC.
*
{XOR}
DTCH
DTCH
1,DCH: Support soft handover, fast power control; Support fast data
rate change.
2,CCH: Don’t support soft handover; Support fast power control for
several CCHs. (CCHBCH/FACH/PCH/RACH/CPCP/DSCH)
3,BCH: Transmit special information of UTRA network or specific
cells, such as: random access code, access slot, or other channels’
transmission diversity types. BCH’s transmission power is high, so
all UEs in the cell can receive the information. The data rate of
BCH is slow and fixed in order to let the low classic UE can
decoding.
4,FACH: a downlink channel; one cell can have several FACHs, but
one channel must transmit with slow bit rate.
5,PCH: the paging mode influences the UE’s power consumption. If UE
adjusts its receiver to intercept the paging information more less,
the UE’s battery can use longer in idle mode.
6,RACH: transmit connection request and little packet data.
*
MAC: Transport Formation Selection(1)
Contrl immediate bit rate by means of changing traffic per
TTI(Transmission Time Interval, is multiple of 10ms)
Transport Block (TB): Bit series to be trasmited from logical
channel
Transport Block Size: Size of TB
Transport Block Set: A group of TB transferred in a TTI
(Multiplexed on logical channel)bb
Transport Block Set Size: Whole bit length contained in a TBS
Transport Block, TB#1
Transport Time Interval, TTI
3,PS services: 336
4,AMR services: 8 types TB Size with different AMR rates
5,CS Stream: different rates with different services
(576(14.4k/28.8k/57.6k),640(32k/64k) etc.
*
Transport Format (TF) defines Transport Block Set (Transport Block
Size, Transport Block Set Size)
Transport Format Set (TFS): Possible TF combinations of a transport
channel. MAC will chose a TF during every TTI
Transport Format Combination (TFC): Determined TF combination in
each TTI, each transport channel
Transport Format Combination Set (TFCS): define all possible TFC
combination method. Thus MAC can process dynamic transport rate
control in different transport channels
TFCS
- Transparent data transfer. This service transmits upper layer
PDUs without adding any protocol information, possibly including
segmentation/reassembly functionality.
- Unacknowledged data transfer. This service transmits upper layer
PDUs without guaranteeing delivery to the peer entity. The
unacknowledged data transfer mode has the following
characteristics:
- Detection of erroneous data: The RLC sublayer shall deliver only
those SDUs to the receiving upper layer that are free of
transmission errors by using the sequence-number check
function.
- Immediate delivery: The receiving RLC sublayer entity shall
deliver a SDU to the upper layer receiving entity as soon as it
arrives at the receiver.
- Acknowledged data transfer. This service transmits upper layer
PDUs and guarantees delivery to the peer entity. In case RLC is
unable to deliver the data correctly, the user of RLC at the
transmitting side is notified. For this service, both in-sequence
and out-of-sequence delivery are supported. In many cases a upper
layer protocol can restore the order of its PDUs. As long as the
out-of-sequence properties of the lower layer are known and
controlled (i.e. the upper layer protocol will not immediately
request retransmission of a missing PDU) allowing out-of-sequence
delivery can save memory space in the receiving RLC. The
acknowledged data transfer mode has the following
characteristics:
- Error-free delivery: Error-free delivery is ensured by means of
retransmission. The receiving RLC entity delivers only error-free
SDUs to the upper layer.
- Unique delivery: The RLC sublayer shall deliver each SDU only
once to the receiving upper layer using duplication detection
function.
- In-sequence delivery: RLC sublayer shall provide support for
in-order delivery of SDUs, i.e., RLC sublayer should deliver SDUs
to the receiving upper layer entity in the same order as the
transmitting upper layer entity submits them to the RLC
sublayer.
- Out-of-sequence delivery: Alternatively to in-sequence delivery,
it shall also be possible to allow that the receiving RLC entity
delivers SDUs to upper layer in different order than submitted to
RLC sublayer at the transmitting side.
- Maintenance of QoS as defined by upper layers. The retransmission
protocol shall be configurable by layer 3 to provide different
levels of QoS. This can be controlled.
- Notification of unrecoverable errors. RLC notifies the upper
layer of errors that cannot be resolved by RLC itself by normal
exception handling procedures, e.g. by adjusting the maximum number
of retransmissions according to delay requirements.
There is a single RLC connection per Radio Bearer.
*
In-sequence delivery of higher layer PDUs, duplicate
detection
Flow control
Protocol error detection and recovery
Ciphering
Suspend/resume function
RLC Functions:
- Segmentation and reassembly. This function performs
segmentation/reassembly of variable-length upper layer PDUs
into/from smaller RLC PDUs. The RLC PDU size is adjustable to the
actual set of transport formats.
- Transfer of user data. This function is used for conveyance of
data between users of RLC services. RLC supports acknowledged,
unacknowledged and transparent data transfer. QoS setting controls
transfer of user data.
- Error correction. This function provides error correction by
retransmission (e.g. Selective Repeat, Go Back N, or a
Stop-and-Wait ARQ) in acknowledged data transfer mode.
- In-sequence delivery of upper layer PDUs. This function preserves
the order of upper layer PDUs that were submitted for transfer by
RLC using the acknowledged data transfer service. If this function
is not used, out-of-sequence delivery is provided.
- Duplicate Detection. This function detects duplicated received
RLC PDUs and ensures that the resultant upper layer PDU is
delivered only once to the upper layer.
- Flow control. This function allows an RLC receiver to control the
rate at which the peer RLC transmitting entity may send
information.
- Sequence number check. This function is used in unacknowledged
mode and guarantees the integrity of reassembled PDUs and provides
a mechanism for the detection of corrupted RLC SDUs through
checking sequence number in RLC PDUs when they are reassembled into
a RLC SDU. A corrupted RLC SDU will be discarded.
- Protocol error detection and recovery. This function detects and
recovers from errors in the operation of the RLC protocol.
- Ciphering. This function prevents unauthorised acquisition of
data. Ciphering is performed in RLC layer for non-transparent RLC
mode.
- Suspend/resume function. Suspension and resumption of data
transfer.
*
BMCBroadcast/Multicast Control
The BMC-SAP provides a broadcast/multicast transmission service in
the user plane on the radio interface for common user data in
unacknowledged mode.
2,PDCP Services provided to upper layers:
PDCP SDU delivery.
Mapping of network PDU from network protocol to RLC protocol
header compression and de-compression in order to reduce the
redundant control information in higher layer data, thus enhance
the transport efficiency in air interface
TCP/IP (RFC2507) - Non-realtime IP
support of Loss-less SRNS Relocation
buffering and retransmit of higher layer data
PDCP Functions:
- Header compression and decompression. Header compression and
decompression of IP data streams (e.g., TCP/IP and RTP/UDP/IP
headers) at the transmitting and receiving entity, respectively.
The header compression method is specific to the particular network
layer, transport layer or upper layer protocol combinations e.g.
TCP/IP and RTP/UDP/IP.
- Transfer of user data. Transmission of user data means that PDCP
receives PDCP SDU from the NAS and forwards it to the RLC layer and
vice versa.
*
Storage of cell broadcast message
Monitoring of traffic volume and CBS (Cell Broadcast Service) radio
resource request
BMC message dispatching
Transport BMC message to higher layer
BMC Functions:
- Storage of Cell Broadcast Messages.
The BMC stores the Cell Broadcast messages received over the
CBC-RNC interface for scheduled transmission.
- Traffic volume monitoring and radio resource request for
CBS.
At the UTRAN side, the BMC calculates the required transmission
rate for Cell Broadcast Service based on the messages received over
the CBC-RNC interface, and requests for appropriate CTCH/FACH
resources from RRC.
- Scheduling of BMC messages.
The BMC receives scheduling information together with each Cell
Broadcast message over the CBC-RNC-interface. Based on this
scheduling information, at the UTRAN side, BMC generates schedule
messages and schedules BMC message sequences accordingly. At the UE
side, BMC evaluates the schedule messages and indicates scheduling
parameters to RRC, which are used by RRC to configure the lower
layers for CBS discontinuous reception.
- Transmission of BMC messages to UE.
This function transmits the BMC messages (Scheduling and Cell
Broadcast messages) according to schedule.
- Delivery of Cell Broadcast messages to upper layer (NAS).
*
- General Control
The GC SAP provides an information broadcast service. This service
broadcasts information to all UEs in a certain geographical
area.
- Notification
The Nt SAP provides paging and notification broadcast services. The
paging service sends information to a specific UE(s). The
information is broadcast in a certain geographical area but
addressed to a specific UE(s).
- Dedicated Control
*
Paging/Notification
Radio Bearer (RB) Managementestablish, reconfig and release,
support NAS services
RRC connection mobility management
Routing of higher layer PDUs
Control of requested QoS and map into different resources of Access
Stratum
Management and control of radio resources
The Radio Resource Control (RRC) layer handles the control plane
signalling of Layer 3 between the UEs and UTRAN. The RRC performs
the following functions:
- Broadcast of information provided by the non-access stratum (Core
Network). The RRC layer performs system information broadcasting
from the network to all UEs. The system information is normally
repeated on a regular basis. The RRC layer performs the scheduling,
segmentation and repetition. This function supports broadcast of
higher layer (above RRC) information. This information may be cell
specific or not. As an example RRC may broadcast Core Network
location service area information related to some specific
cells.
- Broadcast of information related to the access stratum. The RRC
layer performs system information broadcasting from the network to
all UEs. The system information is normally repeated on a regular
basis. The RRC layer performs the scheduling, segmentation and
repetition. This function supports broadcast of typically
cell-specific information.
- Paging/notification. The RRC layer can broadcast paging
information from the network to selected UEs. Higher layers on the
network side can request paging and notification. The RRC layer can
also initiate paging during an established RRC connection.
- Establishment, re-establishment, maintenance and release of an
RRC connection between the UE and UTRAN. The establishment of an
RRC connection is initiated by a request from higher layers at the
UE side to establish the first Signalling Connection for the UE.
The establishment of an RRC connection includes an optional cell
re-selection, an admission control, and a layer 2 signalling link
establishment. The release of an RRC connection can be initiated by
a request from higher layers to release the last Signalling
Connection for the UE or by the RRC layer itself in case of RRC
connection failure. In case of connection loss, the UE requests
re-establishment of the RRC connection. In case of RRC connection
failure, RRC releases resources associated with the RRC
connection.
- Establishment, reconfiguration and release of Radio Bearers. The
RRC layer can, on request from higher layers, perform the
establishment, reconfiguration and release of Radio Bearers in the
user plane. A number of Radio Bearers can be established to an UE
at the same time. At establishment and reconfiguration, the RRC
layer performs admission control and selects parameters describing
the Radio Bearer processing in layer 2 and layer 1, based on
information from higher layers.
- Assignment, reconfiguration and release of radio resources for
the RRC connection. The RRC layer handles the assignment of radio
resources (e.g. codes, CPCH channels) needed for the RRC connection
including needs from both the control and user plane. The RRC layer
may reconfigure radio resources during an established RRC
connection. This function includes coordination of the radio
resource allocation between multiple radio bearers related to the
same RRC connection. RRC controls the radio resources in the uplink
and downlink such that UE and UTRAN can communicate using
unbalanced radio resources (asymmetric uplink and downlink). RRC
signals to the UE to indicate resource allocations for purposes of
handover to GSM or other radio systems.
- RRC connection mobility functions. The RRC layer performs
evaluation, decision and execution related to RRC connection
mobility during an established RRC connection, such as handover,
preparation of handover to GSM or other systems, cell re-selection
and cell/paging area update procedures, based on e.g. measurements
done by the UE.
- Initial cell selection and re-selection in idle mode. Selection
of the most suitable cell based on idle mode measurements and cell
selection criteria.
*
Management and control of RB, transport channel and physical
channel
open loop power control
Support of SRNS relocation
Ciphering control, protection of integrity
CBS related functionsBMC configurationCBS radio resource distribute
request, support of CBS non-continuous receiving
RRC Functions (Continue)
- Outer loop power control. The RRC layer controls setting of the
target of the closed loop power control.
- Control of requested QoS. This function shall ensure that the QoS
requested for the Radio Bearers can be met. This includes the
allocation of a sufficient number of radio resources.
- UE measurement reporting and control of the reporting. The
measurements performed by the UE are controlled by the RRC layer,
in terms of what to measure, when to measure and how to report,
including both UMTS air interface and other systems. The RRC layer
also performs the reporting of the measurements from the UE to the
network.
- Control of ciphering. The RRC layer provides procedures for
setting of ciphering (on/off) between the UE and UTRAN.
- Integrity protection. This function adds a Message Authentication
Code (MAC-I) to those RRC messages that are considered sensitive
and/or contain sensitive information.
- Initial Configuration for CBS
This function performs the initial configuration of the BMC
sublayer.
- Allocation of radio resources for CBS
This function allocates radio resources for CBS based on traffic
volume requirements indicated by BMC. The radio resource allocation
set by RRC (i.e. the schedule for mapping of CTCH onto
FACH/S-CCPCH) is indicated to BMC to enable generation of schedule
messages. The resource allocation for CBS shall be broadcast as
system information.
- Configuration for CBS discontinuous reception
*
RAB, RB and RL
RABThe service that the access stratum provides to the non-access
stratum for transfer of user data between User Equipment and
CN
RBThe service provided by the layer2 for transfer of user data
between User Equipment and Serving RNC
*
Idle mode
Connected mode
Cell_DCH
Cell_FACH
Cell_PCH
URA_PCH
When a UE is switched on, a public land mobile network (PLMN) is
selected and the UE searches for a suitable cell of this PLMN to
camp on.
The NAS shall provide a list of equivalent PLMNs, if available,
that the AS shall use for cell selection and cell
reselection.
The UE searches for a suitable cell of the chosen PLMN and chooses
that cell to provide available services, and tunes to its control
channel. This choosing is known as "camping on the cell". The UE
will, if necessary, then register its presence, by means of a NAS
registration procedure, in the registration area of the chosen
cell.
*
Idle Mode
The UE has no relation to UTRAN, only to CN. For data transfer, a
signalling connection has to be established.
UE camps on a cell
It enables the UE to receive system information from the PLMN
When registered and if the UE wishes to establish an RRC
connection, it can do this by initially accessing the network on
the control channel of the cell on which it is camped
UE can receive "paging" message from control channels of the
cell.
It enables the UE to receive cell broadcast services.
The idle mode tasks can be subdivided into three processes:
PLMN selection and reselection;
Cell selection and reselection;
Location registration.
When a UE is switched on, a public land mobile network (PLMN) is
selected and the UE searches for a suitable cell of this PLMN to
camp on.
The NAS shall provide a list of equivalent PLMNs, if available,
that the AS shall use for cell selection and cell
reselection.
The UE searches for a suitable cell of the chosen PLMN and chooses
that cell to provide available services, and tunes to its control
channel. This choosing is known as "camping on the cell". The UE
will, if necessary, then register its presence, by means of a NAS
registration procedure, in the registration area of the chosen
cell.
*
Connected Mode (Cell-DCH, Cell-FACH, Cell-PCH, URA-PCH)
When at least one signalling connection exists, the UE is in
connected mode and there is normally an RRC connection between UE
and UTRAN. The UE position can be known on different levels:
UTRAN Registration Area (URA) level
The UE position is known on URA level. The URA is a set of
cells
Cell level
The UE position is known on cell level. Different transport channel
types can be used for data transfer:
Common transport channels (RACH / FACH, DSCH, CPCH)
Dedicated transport Channels (DCH)
The connected mode is entered when the RRC connection is
established. The UE is assigned a Radio Network Temporary Identity
(RNTI) to be used as UE identity on common transport channels. Two
types of RNTI exist. The Serving RNC allocates an s-RNTI for all
UEs having an RRC connection. The combination of s-RNTI and an
RNC-ID is unique within a PLMN. c-RNTI is allocated by each
Controlling RNC through which UE is able to communicate on DCCH.
cRNTI is always allocated by UTRAN when a new UE context is created
to an RNC, but the UE needs its c-RNTI only for communicating on
common transport channels.
The UE leaves the connected mode and returns to idle mode when the
RRC connection is released or at RRC connection failure.
Within connected mode the level of UE connection to UTRAN is
determined by the quality of service requirements of the active
radio bearers and the characteristics of the traffic on those
bearers.
The UE-UTRAN interface is designed to support a large number of UEs
using packet data services by providing flexible means to utilize
statistical multiplexing. Due to limitations, such as air interface
capacity, UE power consumption and network h/w availability, the
dedicated resources cannot be allocated to all of the packet
service users at all times.
Variable rate transmission provides the means that for services of
variable rate the data rate is adapted according to the maximum
allowable output power.
The UE state in the connected mode defines the level of activity
associated to the UE. The key parameters of each state are the
required activity and resources within the state and the required
signalling prior to the data transmission. The state of the UE
shall at least be dependent on the application requirement and the
period of inactivity.
Common Packet Channel (CPCH) uplink resources are available to UEs
with an access protocol similar to the RACH. The CPCH resources
support uplink packet communication for numerous UEs with a set of
shared, contention-based CPCH channels allocated to the cell.
The different levels of UE connection to UTRAN are listed
below:
- No signalling connection exists
The UE is in idle mode and has no relation to UTRAN, only to CN.
For data transfer, a signalling connection has to be
established.
- Signalling connection exists
When at least one signalling connection exists, the UE is in
connected mode and there is normally an RRC connection between UE
and UTRAN. The UE position can be known on different levels:
- UTRAN Registration Area (URA) level
The UE position is known on URA level. The URA is a set of
cells
- Cell level
The UE position is known on cell level. Different transport channel
types can be used for data transfer:
- Common transport channels (RACH / FACH, DSCH, CPCH)
- Dedicated transport CHannels (DCH)
Assuming that there exists an RRC connection, there are two basic
families of RRC connection mobility procedures, URA updating and
handover. Different families of RRC connection mobility procedures
are used in different levels of UE connection (cell level and URA
level):
- URA updating is a family of procedures that updates the UTRAN
registration area of a UE when an RRC connection exists and the
position of the UE is known on URA level in the UTRAN;
*
Cell-DCH
UTRAN knows which cell UE is in.
*
In active state
Few data to be transmitted both in uplink and in downlink. There is
no need to allocate dedicated channel for this UE.
Downlink uses FACH and uplink uses RACH.
UE need to monitor the FACH for its relative information.
UTRAN knows which cell UE is in.
Cell-PCH
Monitor PICH, to receive its paging.
lower the power consumption of UE.
UTRAN knows which cell UE is in.
UTRAN have to update cell information of UE when UE roams to
another cell
If there is only few data to be transmitted,there is no need to
allocate dedicated channel. Thus UE will be in Cell-FACH. UE in
Cell-FACH state is communicating via FACH (downlink) and RACH
(uplink) with UTRAN. UE need to monitor the FACH for its relative
information because FACHs is shared for all users in the
cell.
*
Monitor PICH.
UTRAN only knows which URA (UTRAN Registration Area, which consists
of multiple cells) that UE is in.
UTRAN update UE information only after UE has roamed to other
URA.
A better way to lower the resource occupancy and signaling
transmission
*
RRC connection
CELL_DCH
CELL_FACH
CELL_PCH
URA_PCH
IDLE
DEAD
*
SRNC/DRNC
SRNC and DRNC are on a per connection basis between a UE and the
UTRAN
The SRNC handles the connection to one UE, and may borrow radio
resources of a certain cell from the DRNC
Drift RNSs support the Serving RNS by providing radio
resources
A UE in connection state has at least one and only one SRNC, but
can has 0 or multiple DRNCs
CN
SRNC
DRNC
Iu
Iur
Inside the UTRAN, the RNCs of the Radio Network Subsystems can be
interconnected together through the Iur. Iu(s) and Iur are logical
interfaces. Iur can be conveyed over direct physical connection
between RNCs or virtual networks using any suitable transport
network .
*
The CRNC owns the radio resources of a cell
Dynamical control of power for dedicated channels, within limits
admitted by CRNC, is done by the SRNC.
Scheduling of data for dedicated channels is done by the SRNC,
while for common channels it is done by the CRNC
CRNC
Iub
CN
Iu
*
Source RNC/Target RNC
The SRNS Relocation function coordinates the activities when the
SRNS role is to be taken over by another RNS.
Source RNC is the SRNC before SRNs Relocation and Target RNC is the
SRNC after SRNs Relocation
CN
CN
Target
RNC
Serving
RNC
Iu
Iu
Iur
RNC
*