OWA310010 WCDMA Radio Interface Physical Layer ISSUE 1.10 [Compatibility Mode]

WCDMA Air Interface Physical Layer

Confidential Information of Huawei. No Spreading Without Permission

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l UTRAN: UMTS Terrestrial Radio Access Network.

l The UTRAN consists of a set of Radio Network Subsystems connected to the Core Network through the Iu interface.

l A RNS consists of a Radio Network Controller and one or more NodeBs. A NodeB is connected to the RNC through the Iub interface.

l Inside the UTRAN, the RNCs of the RNS 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.



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l The layer 1 supports all functions required for the transmission of bit streams on the physical medium. It is also in charge of measurements function consisting in indicating to higher layers, for example, Frame Error Rate (FER), Signal to Interference Ratio (SIR), interference power, transmit power, … It is basically composed of a “layer 1 management” entity, a “transport channel” entity, and a “physical channel” entity.

l The layer 2 protocol is responsible for providing functions such as mapping, ciphering, retransmission and segmentation. It is made of four sub-layers: MAC (Medium Access Control), RLC (Radio Link Control), PDCP (Packet Data Convergence Protocol) and BMC (Broadcast/Multicast Control).

l The layer 3 is split into 2 parts: the access stratum and the non access stratum. The access stratum part is made of “RRC (Radio Resource Control)” entity and “duplication avoidance” entity. “duplication avoidance” terminates in the CN but is part of the Access Stratum. The higher layer signalling such as Mobility Management (MM) and Call Control (CC) is assumed to belong to the non-access stratum, and therefore not in the scope of 3GPP TSG RAN. In the C-plane, the interface between 'Duplication avoidance' and higher L3 sub-layers (CC, MM) is defined by the General Control (GC), Notification (Nt) and Dedicated Control (DC) SAPs.

l Not shown on the figure are connections between RRC and all the other protocol layers (RLC, MAC, PDCP, BMC and L1), which provide local inter-layer control services.

l The protocol layers are located in the UE and the peer entities are in the NodeB or the RNC.



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l Many functions are managed by the RRC layer. Here is the list of the most important:

p Establishment, re-establishment, maintenance and release of an RRC connection between the UE and UTRAN: it includes an optional cell re-selection, an admission control, and a layer 2 signaling link establishment. When a RNC is in charge of a specific connection towards a UE, it acts asthe Serving RNC.

p Establishment, reconfiguration and release of Radio Bearers: a number of Radio Bearers can be established for a UE at the same time. These bearers are configured depending on the requested QoS. The RNC is also in charge of ensuring that the requested QoS can be met.

p Assignment, reconfiguration and release of radio resources for the RRC connection: it handles the assignment of radio resources (e.g. codes, shared channels). RRC communicates with the UE to indicate new resources allocation when handovers are managed.

p Paging/Notification: it broadcasts paging information from network to UEs.

p Broadcasting of information provided by the non-access stratum (Core Network) or access Stratum. This corresponds to “system information” regularly repeated.

p UE measurement reporting and control of the reporting: RRC indicates what to measure, when and how to report.

p Outer loop power control: controls setting of the target values.

p Control of ciphering: provides procedures for setting of ciphering.

l The RRC layer is defined in the 25.331 specification from 3GPP.



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l The RLC’s main function is the transfer of data from either the user or the control plane over the Radio interface. Two different transfer modes are used:transparent and non-transparent. In non-transparent mode, 2 sub-modes are used: acknowledged or unacknowledged.

l RLC provides services to upper layers:

p data transfer (transparent, acknowledged and unacknowledged modes).

p QoS setting: the retransmission protocol (for AM only) shall be configurable by layer 3 to provide different QoS.

p notification of unrecoverable errors: RLC notifies the upper layers of errors that cannot be resolved by RLC.

l The RLC functions are:

p mapping between higher layer PDUs and logical channels.

p ciphering: prevents unauthorized acquisition of data; performed in RLC layer for non-transparent RLC mode.

p segmentation/reassembly: this function performs segmentation/reassembly of variable-length higher layer PDUs into/from smaller RLC Payload Units. The RLC size is adjustable to the actual set of transport formats (decided when service is established). Concatenation and padding may also be used.

p error correction: done by retransmission (acknowledged data transfer mode only).

p flow control: allows the RLC receiver to control the rate at which the peer RLC transmitting entity may send information.



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l MAC services include:

p Data transfer: service providing unacknowledged transfer of MAC SDUs between peer MAC entities.

p Reallocation of radio resources and MAC parameters: reconfiguration of MAC functions such as change of identity of UE. Requested by the RRC layer.

p Reporting of measurements: local measurements such as traffic volume and quality indication are reported to the RRC layer.

l The functions accomplished by the MAC sub-layer are listed above. Here’s a quick explanation for some of them:

p Priority handling between the data flows of one UE: since UMTS is multimedia, a user may activate several services at the same time, having possibly different profiles (priority, QoS parameters...). Priority handlingconsists in setting the right transport format for a high bit rate service and for a low bit rate service.

p Priority handling between UEs: use for efficient spectrum resourcesutilization for bursty transfers on common and shared channels.

p Ciphering: to prevent unauthorized acquisition of data. Performed in the MAC layer for transparent RLC mode.

p Access Service Class (ACS) selection for RACH transmission: the RACH resources are divided between different ACSs in order to provide different priorities on a random access procedure.



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l PDCP

p UMTS supports several network layer protocols providing protocol transparency for the users of the service.

p Using these protocols (and new ones) shall be possible without any changes to UTRAN protocols. In order to perform this requirement, the PDCP layer has been introduced. Then, functions related to transfer of packets from higher layers shall be carried out in a transparent way by the UTRAN network entities.

p PDCP shall also be responsible for implementing different kinds of optimization methods. The currently known methods are standardized IETF (Internet Engineering Task Force) header compression algorithms.

p Algorithm types and their parameters are negotiated by RRC and indicated toPDCP.

p Header compression and decompression are specific for each network layer protocol type.

p In order to know which compression method is used, an identifier (PID: Packet Identifier) is inserted. Compression algorithms exist for TCP/IP, RTP/UDP/IP, …

p Another function of PDCP is to provide numbering of PDUs. This is done if lossless SRNS relocation is required.

p To accomplish this function, each PDCP-SDUs (UL and DL) is buffered and numbered. Numbering is done after header compression. SDUs are kept until information of successful transmission of PDCP-PDU has been received from RLC. PDCP sequence number ranges from 0 to 65,535.



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l BMC (broadcast/multicast control protocol)

p The main function of BMC protocol are:

p Storage of cell broadcast message. the BMC in RNC stores the cell broadcast message received over the CBC-RNC interface for scheduled transmission.

p Traffic volume monitoring and radio resource request for CBS. On the UTRAN side, the BMC calculates the required transmission rate for the cell broadcast service based on the messages received over the CBC-RNC interface, and requests appropriate .CTCH/FACH resources from from RRC

p Scheduling of BMC message. The BMC receives scheduling information together with each cell broadcast message over the CBC-RNC interface. Based on this scheduling information, on the UTRAN side the BMC generates schedule message and schedules BMC message sequences accordingly. On the UE side ,the 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.

p Transmission of BMC message to UE. The function transmits the BMC messages according to the schedule

p Delivery of cell broadcast messages to the upper layer. This UE function delivers the received non-corrupted cell broadcast messages to the upper layer



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l The layer 1 (physical layer) is used to transmit information under the form of electrical signals corresponding to bits, between the network and the mobile user. This information can be voice, circuit or packet data, and network signaling.

l The UMTS layer 1 offers data transport services to higher layers. The access to these services is through the use of transport channels via the MAC sub-layer.

l These services are provided by radio links which are established by signaling procedures. These links are managed by the layer 1 management entity. One radio link is made of one or several transport channels, and one physical channel.

l The UMTS layer 1 is divided into two sub-layers: the transport and the physical sub-layers. All the processing (channel coding, interleaving, etc.) is done by the transport sub-layer in order to provide different services and their associated QoS. The physical sub-layer is responsible for the modulation, which corresponds to the association of bits (coming from the transport sub-layer) to electrical signals that can be carried over the air interface. The spreading operation is also done by the physical sub-layer.

l These two parts of layer 1 are controlled by the layer 1 management (L1M) entity. It is made of several units located in each equipment, which exchange information through the use of control channels.



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l RAB: The service that the access stratum provides to the non-access stratum for transfer of user data between User Equipment and CN.

l RB: The service provided by the layer 2 for transfer of user data between User Equipment and Serving RNC.

l RL: A "radio link" is a logical association between single User Equipment and a single UTRAN access point. Its physical realization comprises one or more radio bearer transmissions.



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l In terms of protocol layer, the WCDMA radio interface has three types of channels: physical channel, transport channel and logical channel.

l Logical channel: Carrying user services directly. According to the types of the carried services, it is divided into two types: control channel and service channel.

l Transport channel: It is the interface between radio interface layer 2 and layer 1, and it is the service provided for MAC layer by the physical layer. According to whether the information transported is dedicated information for a user or common information for all users, it is divided into dedicated channel and common channel.

l Physical channel: It is the ultimate embodiment of all kinds of information when they are transmitted on radio interface. Each channel which uses dedicated carrier frequency, code (spreading code and scramble) and carrier phase (I or Q) can be regarded as a physical channel.



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l As in GSM, UMTS uses the concept of logical channels.l A logical channel is characterized by the type of information that is transferred.l As in GSM, logical channels can be divided into two groups: control channels for

control plane information and traffic channel for user plane information.l The traffic channels are:

p Dedicated Traffic Channel (DTCH): a point-to-point bi-directionalchannel, that transmits dedicated user information between a UE and the network. That information can be speech, circuit switched data or packet switched data. The payload bits on this channel come from a higher layer application (the AMR codec for example). Control bits can be added by the RLC (protocol information) in case of a non transparent transfer. The MAC sub-layer will also add a header to the RLC PDU.

p Common Traffic Channel (CTCH): a point-to-multipoint downlink channel for transfer of dedicated user information for all or a group of specified UEs. This channel is used to broadcast BMC messages. These messages can either be cell broadcast data from higher layers or schedule messages for support of Discontinuous Reception (DRX) of cell broadcast data at the UE. Cell broadcast messages are services offered by the operator, like indication of weather, traffic, location or rate information.



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l The control channels are:

p Broadcast Control Channel (BCCH): a downlink channel that broadcasts all system information types (except type 14 that is only used in TDD). For example, system information type 3 gives the cell identity. UEs decode system information on the BCH except when in Cell_DCH mode. In that case, they can decode system information type 10 on the FACH and other important signaling is sent on a DCCH.

p Paging Control Channel (PCCH): a downlink channel that transfers paging information. It is used to reach a UE (or several UEs) in idle mode or in connected mode (Cell_PCH or URA_PCH state). The paging type 1 message is sent on the PCCH. When a UE receives a page on the PCCH in connected mode, it shall enter Cell_FACH state and make a cell update procedure.

p Dedicated Control Channel (DCCH): a point-to-point bi-directional channel that transmits dedicated control information between a UE and the network. This channel is used for dedicated signaling after a RRC connection has been done. For example, it is used for inter-frequency handover procedure, for dedicated paging, for the active set update procedure and for the control and report of measurements.

p Common Control Channel (CCCH): a bi-directional channel for transmitting control information between network and UEs. It is used to send messages related to RRC connection, cell update and URA update. This channel is a bit like the DCCH, but will be used when the UE has not yet been identified by the network (or by the new cell). For example, it is used to send the RRC connection request message, which is the first message sent by the UE to get into connected mode. The network will respond on the same channel, and will send him its temporary identities (cell and UTRAN identities). After these initial messages, the DCCH will be used.



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l In order to carry logical channels, several transport channels are defined. They are:

p Broadcast Channel (BCH): a downlink channel used for broadcast of system information into the entire cell.

p Paging Channel (PCH): a downlink channel used for broadcast of control information into the entire cell, such as paging.

p Random Access Channel (RACH): a contention based uplink channel used for initial access or for transmission of relatively small amounts of data (non real-time dedicated control or traffic data).

p Forward Access Channel (FACH): a common downlink channel used for dedicated signaling (answer to a RACH typically), or for transmission of relatively small amounts of data.

p Dedicated Channel (DCH): a channel dedicated to one UE used in uplink or downlink.



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l Now we will begin to discuss the physical channel. Physical channel is the most important and complex channel, and a physical channel is defined by a specific carrier frequency, code and relative phase. In CDMA system, the different code (scrambling code or spreading code) can distinguish the channel. Most channels consist of radio frames and time slots, and each radio frame consists of 15 time slots. There are two types of physical channel: UL and DL.



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l The different physical channels are: p Synchronization Channel (SCH): used for cell search procedure. There is

the primary and the secondary SCHs.p Common Control Physical Channel (CCPCH): used to carry common

control information such as the scrambling code used in DL (there is a primary CCPCH and additional secondary CCPCH).

p Common Pilot Channels (P-CPICH and S-CPICH): used for coherent detection of common channels. They indicate the phase reference.

p Dedicated Physical Data Channel (DPDCH): used to carry dedicated data coming from layer 2 and above (coming from DCH).

p Dedicated Physical Control Channel (DPCCH): used to carry dedicated control information generated in layer 1 (such as pilot, TPC and TFCI bits).

p Page Indicator Channel (PICH): carries indication to inform the UE that paging information is available on the S-CCPCH.

p Acquisition Indicator Channel (AICH): it is used to inform a UE that the network has received its access request.

p High Speed Physical Downlink Shared Channel (HS-PDSCH): it is used to carry subscribers BE service data (mapping on HSDPA) coming from layer 2.

p High Speed Shared Control Channel (HS-SCCH): it is used to carry control message to HS-PDSCH such as modulation scheme, UE ID etc.



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l The different physical channels are:

p Dedicated Physical Data Channel (DPDCH): used to carry dedicated data coming from layer 2 and above (coming from DCH).

p Dedicated Physical Control Channel (DPCCH): used to carry dedicated control information generated in layer 1 (such as pilot, TPC and TFCI bits).

p Physical Random Access Channel (PRACH): used to carry random access information when a UE wants to access the network.

p High Speed Dedicated Physical Control Channel (HS-DPCCH): it is used to carry feedback message to HS-PDSCH such CQI,ACK/NACK.



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l When a UE is turned on, the first thing it does is to scan the UMTS spectrum andfind a UMTS cell. After that, it has to find the primary scrambling code used by that cell in order to be able to decode the BCCH (for system information). This is done with the help of the Synchronization Channel.

l Each cell of a NodeB has its own SCH timing, so that there is no overlapping.

l The SCH is a pure downlink physical channel broadcasted over the entire cell. It is transmitted unscrambled during the first 256 chips of each time slot, in time multiplex with the P-CCPCH. It is the only channel that is not spread over the entire radio frame. The SCH provides the primary scrambling code group (one out of 64 groups), as well as the radio frame and time slot synchronization.

l The SCH consists of two sub-channels, the primary and secondary SCH. These sub-channels are sent in parallel using code division during the first 256 chips of each time slot. P-SCH always transmits primary synchronization code. S-SCH transmits secondary synchronization codes.

l The primary synchronization code is repeated at the beginning of each time slot. The same code is used by all the cells and enables the mobiles to detect the existence of the UMTS cell and to synchronize itself on the time slot boundaries. This is normally done with a single matched filter or any similar device. The slot timing of the cell is obtained by detecting peaks in the matched filter output.

l This is the first step of the cell search procedure. The second step is done using the secondary synchronization channel.



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l The S-SCH also consists of a code, the Secondary Synchronization Code (SSC) that indicates which of the 64 scrambling code groups the cell’s downlink scrambling code belongs to. 16 different SSCs are defined. Each SSC is a 256 chip long sequence.

l There is one specific SSC transmitted in each time slot, giving us a sequence of 15 SSCs. There is a total of 64 different sequences of 15 SSCs, corresponding to the 64 primary scrambling code groups. These 64 sequences are constructed so that one sequence is different from any other one, and different from any rotated version of any sequence. The UE correlates the received signal with the 16 SSCs and identifies the maximum correlation value.

l The S-SCH provides the information required to find the frame boundaries and the downlink scrambling code group (one out of 64 groups). The scrambling code (one out of 8) can be determined afterwards by decoding the P-CPICH. The mobile will then be able to decode the BCH.



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l The Common Pilot Channel (CPICH) is a pure physical control channel broadcasted over the entire cell. It is not linked to any transport channel. It consists of a sequence of known bits that are transmitted in parallel with the primary and secondary CCPCH.

l The PCPICH is used by the mobile to determine which of the 8 possible primary scrambling codes is used by the cell, and to provide the phase reference for common channels.

l Finding the primary scrambling code is done during the cell search procedure through a symbol-by-symbol correlation with all the codes within the code group. After the primary scrambling code has been identified, the UE can decode system information on the P-CCPCH.

l The P-CPICH is the phase reference for the SCH, P-CCPCH, AICH and PICH. It is broadcasted over the entire cell. The channelization code used to spread the P-CPICH is always Cch,256,0 (all ones). Thus, the P-CPICH is a fixed rate channel. Also, it is always scrambled with the primary scrambling code of the cell.



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l The Primary Common Control Physical Channel (P-CCPCH) is a fixed rate (SF=256) downlink physical channel used to carry the BCH transport channel. It is broadcasted continuously over the entire cell like the P-CPICH.

l The figure above shows the frame structure of the P-CCPCH. The frame structure is special because it does not contain any layer 1 control bits. The P-CCPCH only has one fix predefined transport format combination, and the only bits transmitted are data bits from the BCH transport channel. It is important to note that the P-CCPCH is not transmitted during the first 256 chips of the slot. In fact, another physical channel (SCH) is transmitted during that period of time. Thus, the SCH and the P-CCPCH are time multiplexed on every time slot.

l Channelization code Cch,256,1 is always used to spread the P-CCPCH.



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l The Page Indicator Channel (PICH) is a fixed rate (30kbps, SF=256) physical channel used by the NodeB to inform a UE (or a group of UEs) that a paging information will soon be transmitted on the PCH. Thus, the mobile only decodes the S-CCPCH when it is informed to do so by the PICH. This enables to do other processing and to save the mobiles’ battery.

l The PICH carries Paging Indicators (PI), which are user specific and calculated by higher layers. It is always associated with the S-CCPCH to which the PCH is mapped.

l The frame structure of the PICH is illustrated above. It is 10 ms long, and always contains 300 bits (SF=256). 288 of these bits are used to carry paging indicators, while the remaining 12 are not formally part of the PICH and shall not be transmitted. That part of the frame (last 12 bits) is reserved for possible future use.

l In order not to waste radio resources, several PIs are multiplexed in time on the PICH. Depending on the configuration of the cell, 18, 36, 72 or 144 paging indicators can be multiplexed on one PICH radio frame. Thus, the number of bits reserved for each PI depends of the number of PIs per radio frame. For example, if there is 72 PIs in one radio frame, there will be 4 (288/72) consecutive bits for each PI. These bits are all identical. If the PI in a certain frame is “1”, it is an indication that the UE associated with that PI should read the corresponding frame of the S-CCPCH.



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l The Secondary Common Control Physical Channel (S-CCPCH) is used to carry the FACH and PCH transport channels. Unlike the P-CCPCH, it is not broadcasted continuously. It is only transmitted when there is a PCH or FACH information to transmit. At the mobile side, the mobile only decodes the S-CCPCH when it expects a useful message on the PCH or FACH.

l A UE will expect a message on the PCH after indication from the PICH (page indicator channel), and it will expect a message on the FACH after it has transmitted something on the RACH.

l The FACH and the PCH can be mapped on the same or on separate S-CCPCHs. If they are mapped on the same S-CCPCH, TFCI bits have to be sent to support multiple transport formats

l The figure above shows the frame structure of the S-CCPCH. There are 18 different slot formats determining the exact number of data, pilot and TFCI bits. The data bits correspond to the PCH and/or FACH bits coming from the transport sub-layer. Pilot bit are typically used when beamforming techniques are used.

l The SF ranges from 4 to 256. The channelization code is assigned by the RRC layer as is the scrambling code, and they are fixed during the communication. They are sent on the BCCH so that every UE can decode the channel.

l As said before, FACH can be used to carry user data. The difference with the dedicated channel is that it cannot use fast power control, nor soft handover. The advantage is that it is a fast access channel.



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l The Physical Random Access Channel (PRACH) is used by the UE to access the network and to carry small data packets. It carries the RACH transport channel. The PRACH is an open loop power control channel, with contention resolution mechanisms (ALOHA approach) to enable a random access from several users.

l The PRACH is composed of two different parts: the preamble part and the message part that carries the RACH message. The preamble is an identifier which consists of 256 repetitions of a 16 chip long signature (total of 4096 chips). There are 16 possible signatures, basically, the UE randomly selects one of the 16 possible preambles and transmits it at increasing power until it gets a response from the network (on the AICH). That preamble is scrambled before being sent. That is a sign that the power level is high enough and that the UE is authorized to transmit, which it will do after acknowledgment from the network. If the UE doesn’t get a response from the network, it has to select a new signature to transmit.

l The message part is 10 or 20 ms long (split into 15 or 30 time slots) and is made of the RACH data and the layer 1 control information.



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l The data and control bits of the message part are processed in parallel. The SF of the data part can be 32, 64, 128 or 256 while the SF of the control part is always 256. The control part consists of 8 pilot bits for channel estimation and 2 TFCI bits to indicate the transport format of the RACH (transport channel), for a total of 10 bits per slot.

l The OVSF codes to use (one for RACH data and one for control) depend on the signature that was used for the preamble (for signatures s=0 to s=15: OVSFcontrol= Cch,256,m, where m=16s + 15; OVSFdata= Cch,SF,m, where m=SF*s/16.



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l The PRACH transmission is based on the access frame structure. The access frame is access of 15 access slots and lasts 20 ms (2 radio frames).

l To avoid too many collisions and to limit interference, a UE must wait at least 3 or 4 access slots between two consecutive preambles.

l The PRACH resources (access slots and preamble signatures) can be divided between different Access Service Classes (ASC) in order to provide different priorities of RACH usage. The ASC number ranges from 0 (highest priority) to 7 (lowest priority).



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l The Acquisition Indicator Channel (AICH) is a common downlink channel used to control the uplink random accesses. It carries the Acquisition Indicators (AI), each corresponding to a signature on the PRACH (uplink). When the NodeB receives the random access from a mobile, it sends back the signature of the mobile to grant its access. If the NodeB receives multiple signatures, it can sent all these signatures back by adding the together. At reception, the UE can apply its signature to check if the NodeB sent an acknowledgement (taking advantage of the orthogonality of the signatures).

l The AICH consists of a burst of data transmitted regularly every access slot frame. One access slot frame is formed of 15 access slots, and lasts 2 radio frames (20 ms). Each access slot consists of two parts, an acquisition indicator part of 32 real-valued symbols and a long part during which nothing is transmitted to avoid overlapping due to propagation delays.

l s (with values 0, +1 and -1, corresponding to the answer from the network to a specific user) and the 32 chip long sequence <bs,j> is given by a predefined table. There are 16 sequences <bs,j>, each corresponding to one PRACH signatures. A maximum of 16 AIs can be sent in each access slot. The user can multiply the received multi-level signal by the signature it used to know if its access was granted.

l The SF used is always 256 and the OVSF code used by the cell is indicated in system information type 5.



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l There are two kinds of uplink dedicated physical channels, the Dedicated Physical Data Channel (DPDCH) and the Dedicated Physical Control Channel (DPCCH).The DPDCH is used to carry the DCH transport channel. The DPCCH is used to carry the physical sub-layer control bits.

l Each DPCCH time slot consists of Pilot, TFCI，FBI，TPC

l Pilot is used to help demodulation

l TFCI: transport format control indicator

l FBI:used for the FBTD. (feedback TX diversity)

l TPC: used to transport power control command.



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l On the figure above, we can see the DPDCH and DPCCH time slot constitution. The parameter k determines the number of symbols per slot. It is related to the spreading factor (SF) of the DPDCH by this simple equation: SF=256/2k. The DPDCH SF ranges from 4 to 256. The SF for the uplink DPCCH is always 256, which gives us 10 bits per slot. The exact number of pilot, TFCI, TPC and FBI bits is configured by higher layers. This configuration is chosen from 12 possible slot formats. It is important to note that symbols are transmitted during all slots for the DPDCH



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l The uplink DPDCH and DPCCH are I/Q code multiplexed. But the downlink DPDCH and DPCCH is time multiplexed. This is main difference.

l Basically, there are two types of downlink DPCH. They are distinguished by the use or non use of the TFCI field. TFCI bits are not used for fixed rate services or when the TFC doesn’t change.



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l We have known that the uplink DPDCH and DPCCH are I/Q code multiplexed. But the downlink DPDCH and DPCCH is time multiplexed. This is main difference. The parameter k in the figure above determines the total number of bits per time slot. It is related to the SF, which ranges from 4 to 512. The chips of one slot is also 2560.

l Downlink physical channels are used to carry user specific information like speech, data or signaling, as well as layer 1 control bits. Like it was mentioned before, the payload from the DPDCH and the control bits from the DPCCH are time multiplexed on every time slot. The figure above shows how these two channels are multiplexed. There is only one DPCCH in downlink for one user.



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l HS-PDSCH is a downlink physical channel that carries user data and layer 2 overhead bits mapped from the transport channel: HS-DSCH.

l The user data and layer 2 overhead bits from HS-DSCH is mapped onto one or several HS-PDSCH and transferred in 2ms subframe using one or several channelization code with fixed SF=16.



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l HS-SCCH uses a SF=128 and has q time structure based on a sub-frame of length 2 ms, i.e. the same length as the HS-DSCH TTI. The timing of HS-SCCH starts two slot prior to the start of the HS-PDSCH subframe.

l The following information is carried on the HS-SCCH (7 items)

p Modulation scheme(1bit) QPSK or 16QAM

p Channelization code set (7bits)

p Transport block size ( 6bits)

p HARQ process number (3bits)

p Redundancy version (3bits)

p New Data Indicator (1bit)

p UE identity (16 bits)

l In each 2 ms interval corresponding to one HS-DSCH TTI , one HS-SCCH carries physical-layer signalling to a single UE. As there should be a possibility for HS-DSCH transmission to multiple users in parallel (code multiplex), multiplex HS-SCCH may be needed in a cell. The specification allows for up to four HS-SCCHs as seen from a UE point of view .i.e. UE must be able to decode four HS-SCCH.



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l The uplink HS-DPCCH consists of:

p Acknowledgements for HARQ

p Channel Quality Indicator (CQI)

l As the HS-DPCCH uses SF=256, there are a total of 30 channel bits per 2 ms sub frame (3 time slot). The HS-DPCCH information is divided in such a way that the HARQ acknowledgement is transmitted in the first slot of the subframe while the channel quality indication is transmitted in the rest slot.



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l This page indicates how the mapping can be done between logical, transport and physical channels. Not all physical channels are represented because not all physical channels correspond to a transport channel.

l The mapping between logical channels and transport channels is done by the MAC sub-layer.

l Different connections can be made between logical and transport channels:

p BCCH is connected to BCH and may also be connected to FACH;

p DTCH can be connected to either RACH and FACH, to RACH and DSCH, to DCH and DSCH, to a DCH or a CPCH;

p CTCH is connected to FACH;

p DCCH can be connected to either RACH and FACH, to RACH and DSCH, to DCH and DSCH, to a DCH or a CPCH;

p PCCH is connected to PCH;

p CCCH is connected to RACH and FACH.

l These connections depend on the type of information on the logical channels.



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l The purpose of the Cell Search Procedure is to give the UE the possibility of finding a cell and of determining the downlink scrambling code and frame synchronization of that cell. This is typically performed in 3 steps:

p PSCH (Slot synchronization): The UE uses the SCH’s primary synchronization code to acquire slot synchronization to a cell. The primary synchronization code is used by the UE to detect the existence of a cell and to synchronize the mobile on the TS boundaries. This is typically done with a single filter (or any similar device) matched to the primary synchronization code which is common to all cells. The slot timing of the cell can be obtained by detecting peaks in the matched filter output.

p SSCH (Frame synchronization and code-group identification): The secondary synchronization codes provide the information required to find the frame boundaries and the group number. Each group number corresponds to a unique set of 8 primary scrambling codes. The frame boundary and the group number are provided indirectly by selecting a suite of 15 secondary codes. 16 secondary codes have been defined C1, C2, ….C16. 64 possible suites have been defined, each suite corresponds to one of the 64 groups. Each suite of secondary codes is composed of 15 secondary codes (chosen in the set of 16), each of which will be transmitted in one time slot. When the received codes matches one of the possible suites, the UE has both determined the frame boundary and the group number.

p PCPICH (Scrambling-code identification): The UE determines the exact primary scrambling code used by the found cell. The primary scrambling code is typically identified through symbol-by-symbol correlation over the PCPICH with all the codes within the code group identified in the second step. After the primary scrambling code has been identified, the Primary CCPCH can be detected and the system- and cell specific BCH information can be read.



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l Physical random access procedure

p 1. Derive the available uplink access slots, in the next full access slot set, for the set of available RACH sub-channels within the given ASC. Randomly select one access slot among the ones previously determined. If there is no access slot available in the selected set, randomly select one uplink access slot corresponding to the set of available RACH sub-channels within the given ASC from the next access slot set. The random function shall be such that each of the allowed selections is chosen with equal probability；

p 2. Randomly select a signature from the set of available signatures within the given ASC.；

p 3. Set the Preamble Retransmission Counter to Preamble_ Retrans_ Max

p 4. Set the parameter Commanded Preamble Power to Preamble_Initial_Power

p 5. Transmit a preamble using the selected uplink access slot, signature, and preamble transmission power.

p 6. If no positive or negative acquisition indicator (AI ≠ +1 nor –1) corresponding to the selected signature is detected in the downlink access slot corresponding to the selected uplink access slot:

n A: Select the next available access slot in the set of available RACH sub-channels within the given ASC;

n B: select a signature;n C: Increase the Commanded Preamble Power;n D: Decrease the Preamble Retransmission Counter by one. If the Preamble Retransmission

Counter > 0 then repeat from step 6. Otherwise exit the physical random access procedure.p 7. If a negative acquisition indicator corresponding to the selected signature is detected in the downlink

access slot corresponding to the selected uplink access slot, exit the physical random access procedureSignature

p 8. If a positive acquisition indicator corresponding to the selected signature is detected , Transmit the random access message three or four uplink access slots after the uplink access slot of the last transmitted preamble

p 9. exit the physical random access procedure



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l The layer 1 supports all functions required for the transmission of bit streams on the physical medium. It is also in charge of measurements function consisting in indicating to higher layers, for example, Frame Error Rate (FER), Signal to Interference Ratio (SIR), interference power and transmit power.

l The layer 2 protocol is responsible for providing functions such as mapping, ciphering, retransmission and segmentation. It is made of four sublayers: MAC (Medium Access Control), RLC (Radio Link Control), PDCP (Packet Data Convergence Protocol) and BMC (Broadcast/Multicast Control).

l The layer 3 is split into 2 parts: the access stratum and the non access stratum. The access stratum part is made of “RRC (Radio Resource Control)” entity and “duplication avoidance” entity. The non access stratum part is made of CC, MM parts.

l Not shown on the figure are connections between RRC and all the other protocol layers (RLC, MAC, PDCP, BMC and L1), which provide local inter-layer control services.

l The protocol layers are located in the UE and the peer entities are in the NodeB or the RNC.



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l Protocol structures in UTRAN terrestrial interfaces are designed according to the same general protocol model. This model is shown in above slide. The structure is based on the principle that the layers and planes are logically independent of each other and, if needed, parts of the protocol structure may be changed in the future while other parts remain intact.

l Horizontal Layers

p The protocol structure consists of two main layers, the Radio Network Layer (RNL) and the Transport Network Layer (TNL). All UTRAN-related issues are visible only in the Radio Network Layer, and the Transport Network Layer represents standard transport technology that is selected to be used for UTRAN but without any UTRAN-specific changes.

l Vertical Planes

p Control Plane

p The Control Plane is used for all UMTS-specific control signaling. It includes the Application Protocol (i.e. RANAP in Iu, RNSAP in Iur and NBAP in Iub), and the Signaling Bearer for transporting the Application Protocol messages. The Application Protocol is used, among other things, for setting up bearers to the UE (i.e. the Radio Access Bearer in Iu and subsequently the Radio Link in Iur and Iub). In the three plane structure the bearer parameters in the Application Protocol are not directly tied to the User Plane technology, but rather are general bearer parameters. The Signaling Bearer for the Application Protocol may or may not be of the same type as the Signaling Bearer for the ALCAP. It is always set up by O&M actions.



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p User Plane

p All information sent and received by the user, such as the coded voice in a voice call or the packets in an Internet connection, are transported via the User Plane. The User Plane includes the Data Stream(s), and the Data Bearer (s) for the Data Stream(s). Each Data Stream is characterized by one or more frame protocols specified for that interface.

p Transport Network Control Plane

p The Transport Network Control Plane is used for all control signaling within the Transport Layer. It does not include any Radio Network Layer information. It includes the ALCAP protocol that is needed to set up the transport bearers (Data Bearer) for the User Plane. It also includes the Signaling Bearer needed for the ALCAP. The Transport Network Control Plane is a plane that acts between the Control Plane and the User Plane. The introduction of the Transport Network Control Plane makes it possible for the Application Protocol in the Radio Network Control Plane to be completely independent of the technology selected for the Data Bearer in the User Plane.

l About AAl2 and AAL5

p Above the ATM layer we usually find an ATM adaptation layer (AAL). Its function is to process the data from higher layers for ATM transmission.

p This means segmenting the data into 48-byte chunks and reassembling the original data frames on the receiving side. There are five different AALs (0, 1, 2, 3/4, and 5). AAL0 means that no adaptation is needed. The other adaptation layers have different properties based on three parameters:

n Real-time requirements;n Constant or variable bit rate;n Connection-oriented or connectionless data transfer.

p The usage of ATM is promoted by the ATM Forum. The Iu interface uses two AALs: AAL2 and AAL5.

p AAL2 is designed for the transmission of connection oriented, real-time data streams with variable bit rates.

p AAL5 is designed for the transmission of connectionless data streams with variable bit rates.



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l Protocol Structure for Iu CS

p The Iu CS overall protocol structure is depicted in above slide. The three planes in the Iu interface share a common ATM (Asynchronous Transfer Mode) transport which is used for all planes. The physical layer is the interface to the physical medium: optical fiber, radio link or copper cable. The physical layer implementation can be selected from a variety of standard off-the-shelf transmission technologies, such as SONET, STM1, or E1.

l Iu CS Control Plane Protocol Stack

p The Control Plane protocol stack consists of RANAP, on top of Broadband (BB) SS7 (Signaling System #7) protocols. The applicable layers are the Signaling Connection Control Part (SCCP), the Message Transfer Part (MTP3-b) and SAAL-NNI (Signaling ATM Adaptation Layer for Network to Network Interfaces).

l Iu CS Transport Network Control Plane Protocol Stack

p The Transport Network Control Plane protocol stack consists of the Signaling Protocol for setting up AAL2 connections (Q.2630.1 and adaptation layer Q.2150.1), on top of BB SS7 protocols. The applicable BB SS7 are those described above without the SCCP layer.

l Iu CS User Plane Protocol Stack

p A dedicated AAL2 connection is reserved for each individual CS service.



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l Protocol Structure for Iu PS

p The Iu PS protocol structure is represented in above slide. Again, a common ATM transport is applied for both User and Control Plane. Also the physical layer is as specified for Iu CS.

l Iu PS Control Plane Protocol Stack

p The Control Plane protocol stack consists of RANAP, on top of Broadband (BB) SS7 (Signaling System #7) protocols. The applicable layers are the Signaling Connection Control Part (SCCP), the Message Transfer Part (MTP3-b) and SAAL-NNI (Signaling ATM Adaptation Layer for Network to Network Interfaces).

l Iu PS Transport Network Control Plane Protocol Stack

p The Transport Network Control Plane is not applied to Iu PS. The setting up of the GTP tunnel requires only an identifier for the tunnel, and the IP addresses for both directions, and these are already included in the RANAP RAB Assignment messages.

l Iu PS User Plane Protocol Stack

p In the Iu PS User Plane, multiple packet data flows are multiplexed on one or several AAL5 PVCs. The GTP-U (User Plane part of the GPRS Tunneling Protocol) is the multiplexing layer that provides identities for individual packet data flow. Each flow uses UDP connectionless transport and IP addressing.



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l The Iub interface is the terrestrial interface between NodeB and RNC. The Radio Network Layer defines procedures related to the operation of the NodeB. The Transport Network Layer defines procedures for establishing physical connections between the NodeB and the RNC.

l The Iub application protocol, NodeB application part ( NBAP ) initiates the establishment of a signaling connection over Iub . It is divided into two essential components, CCP and NCP.

l NCP is used for signaling that initiates a UE context for a dedicated UE or signals that is not related to specific UE. Example of NBAP-C procedure are cell configuration , handling of common channels and radio link setup

l CCP is used for signaling relating to a specific UE context.

l SAAL is an ATM Adaptation Layer that supports communication between signaling entities over an ATM link.

l The user plane Iub Frame Protocol ( FP ), defined the structure of the frames and the basic in band control procedure for every type of transport channel. There are DCH-FP, RACH-FP, FACH-FP, HS-DSCH FP and PCH FP.



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l Iur interface connects two RNCs. The protocol stack for the Iur is shown in above slide.

l The RNSAP protocol is the signaling protocol defined for the Iur interface.



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l In the idle mode, when the non-access layer of the UE requests to establish a signaling connection, the UE will initiate the RRC connection procedure. Each UE has up to one RRC connection only.

l When the SRNC receives an RRC CONNECTION REQUEST message from the UE, the Radio Resource Management (RRM) module of the RNC determines whether to accept or reject the RRC connection request according to a specific algorithm. If accepting the request, the RRM module determines whether to set up the RRC connection on a Dedicated Channel (DCH) or on a Common Channel (CCH) according to a specific RRM algorithm.

l Description:

p The UE sends an RRC CONNECTION REQUEST message to the SRNC through the uplink CCCH, requesting the establishment of an RRC connection.

p Based on the RRC connection request cause and the system resource state, the SRNC decides to establish the connection on the common channel.

p The SRNC sends an RRC CONNECTION SETUP message to the UE through the downlink CCCH. The message contains the information about the CCH.

p The UE sends an RRC CONNECTION SETUP COMPLETE message to the SRNC through the uplink CCCH.



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l Typically, an RRC connection is set up on the DCH.

l Description:

p The UE sends an RRC Connection Request message via the uplink CCCH to request to establish an RRC connection.

p Based on the RRC connection request cause and the system resource state, the SRNC decides to establish the connection on the dedicated channel, and allocates the RNTI and L1 and L2 resources.

p The SRNC sends a Radio Link Setup Request message to Node B, requesting the Node B to allocate specific radio link resources required by the RRC connection.

p After successfully preparing the resources, the Node B responds to the SRNC with the Radio Link Setup Response message.

p The SRNC initiates the establishment of Iub user plane transport bearer with the ALCAP protocol and completes the synchronization between the RNC and the Node B.

p The SRNC sends an RRC Connection Setup message to the UE in the downlink CCCH.

p The UE sends an RRC Connection Setup Complete message to the SRNC in the uplink DCCH.



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ID Name Recommended value

ORIGCONVCALLEST Originating Conversational Call DCH_13.6K_SIGNALLING

ORIGSTREAMCALLEST Originating Streaming Call DCH_13.6K_SIGNALLING

ORIGINTERCALLEST Originating Interactive Call DCH_13.6K_SIGNALLING

ORIGBKGCALLEST Originating Background Call DCH_13.6K_SIGNALLING

ORIGSUBSTRAFFCALLEST Originating Subscribed traffic Call DCH_13.6K_SIGNALLING

TERMCONVCALLEST Terminating Conversational Call DCH_13.6K_SIGNALLING

TERMSTREAMCALLEST Terminating Streaming Call DCH_13.6K_SIGNALLING

TERMINTERCALLEST Terminating Interactive Call DCH_13.6K_SIGNALLING

TERMBKGCALLEST Terminating Background Call DCH_13.6K_SIGNALLING

EMERGCALLEST Emergency Call RRC establish type DCH_13.6K_SIGNALLING

INTERRATCELLRESELEST Inter-RAT cell re-selection DCH_3.4K_SIGNALLING

INTERRATCELLCHGORDEREST Inter-RAT cell change order DCH_3.4K_SIGNALLING

REGISTEST Registration DCH_13.6K_SIGNALLING

DETACHEST Detach FACH

ORIGHIGHPRIORSIGEST Originating High Priority Signaling DCH_13.6K_SIGNALLING

ORIGLOWPRIORSIGEST Originating Low Priority Signaling FACH

CALLREEST Call re-establishment DCH_3.4K_SIGNALLING

TERMHIGHPRIORSIGEST Terminating High Priority Signaling DCH_13.6K_SIGNALLING

TERMLOWPRIORSIGEST Terminating Low Priority Signaling FACH

TERMCAUSEUNKNOWN Terminating cause unknown FACH

DEFAULTEST Spare RRC establish DCH_3.4K_SIGNALLING

l RRC Connection Setup Causes and corresponding bear:



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l After the RRC connection between the UE and the UTRAN is successfully set up, the UE sets up a signaling connection with the CN via the RNC for NAS information exchange between the UE and the CN, such as authentication, service request and connection setup. This is also called the NAS signaling setup procedure.

l 1. The UE sends an INITIAL DIRECT TRANSFER message to the SRNC through the RRC connection. The message contains the initial NAS information to be sent to the CN by the UE.

l 2. The SRNC receives the INITIAL DIRECT TRANSFER message from the UE and sends an INITIAL UE MESSAGE to the CN through the Iu interface. The INITIAL UE MESSAGE contains the NAS information to be sent to the CN by the UE. The content of the NAS information is CM SERVICE REQUEST.

l 3. If the signaling connection is set up, CN will send COMMON ID message to SRNC.



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l 1. The UE sends to the SRNC an UPLINK DIRECT TRANSFER message that contains the number of the callee and the information about the bearing capability of the call.

l 2. The SRNC transparently sends the contents of the UPLINK DIRECT TRANSFER message to the CN through a DIRECT TRANSFER message.

l 3. The CN sends a DIRECT TRANSFER message to the SRNC. The message indicates CALL PROCEEDING and contains the information about the negotiated bearing capability of the call.

l 4. The SRNC transparently sends the contents of the DIRECT TRANSFER message to the UE through a DOWNLINK DIRECT TRANSFER message.

l 5. A Radio Access Bearer (RAB) is set up. For details, refer to next page.

l 6. When the callee rings, the CN sends to the SRNC a DIRECT TRANSFER message, indicating ALERTING.


l 8. The CN sends to the SRNC a DIRECT TRANSFER message, indicating CONNECT. This means the callee has answered the call.


l 10. The UE sends an UPLINK DIRECT TRANSFER message to the SRNC.

l 11. The SRNC transparently sends the contents of the UPLINK DIRECT TRANSFER message to the CN through a DIRECT TRANSFER message, indicating CONNECT ACKNOWLEDGE.



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l The RAB refers to the user plane bearer that is used to transfer voice, data and multimedia services between the UE and the CN. The UE needs to complete the RRC connection establishment before setting up the RAB. RAB is the carrier which is provided by AS for NAS. RAB establishment flow mainly includes the AAL2 PATH establishment of Iu and Iub interface, also includes the reconfiguration process of radio resource.

l The RAB setup is initiated by the CN and executed by the UTRAN. The basic procedure is as follows:

p 1. The CN sends an RAB ASSIGNMENT REQUEST message to the SRNC to initiate the RAB setup procedure.

p 2. The SRNC maps the Quality of Service (QoS) parameters for the RAB to the ATM Adaptation Layer type 2 (AAL2) link characteristic parameters and radio resource characteristic parameters. The ALCAP on the Iu interface initiates a setup procedure for an Iu user plane transport bearer according to the AAL2 link characteristic parameters. (For the PS domain, this step does not exist.)

p 3. The SRNC sends to the NodeB a RADIO LINK RECONFIGURATION PREPARE message, requesting the NodeB to prepare for adding one or more DCHs to the existing radio links for carrying the RAB.

p 4. The NodeB allocates the appropriate resources and then sends a RADIO LINK RECONFIGURATION READY message to the SRNC.



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l 1. The SRNC sends an RRC CONNECTION RELEASE message to the UE through the CCCH.

l 2. The UE sends an RRC CONNECTION RELEASE COMPLETE message to the SRNC.



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l 1. The SRNC sends an RRC CONNECTION RELEASE message to the UE through the DCCH.

p NOTE: The SRNC may send the RRC CONNECTION RELEASE message several times to increase the probability of proper reception of the message by the UE. The RRC SNs of these messages are the same. The number of retransmissions and the transmission intervals are determined by the SRNC. If the SRNC does not receive an RRC CONNECTION RELEASE COMPLETE message from the UE after sending the RRC CONNECTION RELEASE message for four times, the SRNC regards that the UE has released the RRC connection.

l 2. The UE sends an RRC CONNECTION RELEASE COMPLETE message to the SRNC.

l 3. The SRNC sends to the NodeB a RADIO LINK DELETION REQUEST message, requesting the NodeB to delete the radio link resources in the NodeB.

l 4. After releasing the resources, the NodeB sends a RADIO LINK DELETION RESPONSE message to the SRNC.

l 5. The SRNC uses the ALCAP protocol to initiate an Iub user plane transport bearer release procedure.



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OWA310010 WCDMA Radio Interface Physical Layer ISSUE 1.10 [Compatibility Mode]

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Transcript of OWA310010 WCDMA Radio Interface Physical Layer ISSUE 1.10 [Compatibility Mode]