1004420_634405274330339412

Topics 1.Nemo Events and Definition 2.RRC and Layer3 messages 3.SIB Information,Measument Control (MC),Measurement Report (MR) 4.CS and PS Call Flow 5.Cell Reselection, SHO and ISHO

Nemo Events and Definitions


MOC/MTC Call Flow timing

MOC

M T C


Block error ratio:BLER is measured from the CRC – Transport Block (TB) is a basic unit that is exchanged between Layer 1 and Layer 2 (MAC). Layer 1 adds CRC for each TB and BLER is calculated from the CRC

When do I have to perform a cell/ URA update?

Cell update causes in priority order: • Uplink data transmission in URA_PCH, CELL_PACH • Paging response in URA_PCH, CELL_PACH • Radio link failure in CELL_DCH (*) • Re-entering service area in CELL_FACH, CELL_PCH • RLC unrecoverable error in all sub-states • Cell reselection in CELL_FACH, CELL_PCH • Periodical cell update in CELL_FACH, CELL_PCH

URA update causes in priority order: (the UE is in the URA_PCH sub-state) • URA reselection • Periodic URA update

RRC and Layer-3 Messages System Information Blocks (SIB)

RRC Modes

CELL_FACH

CELL_DCH • DCCH and – if configured – DTCH • Dedicate physical channel in use • UE location known on active set cell level • UE responsible for measurement reporting • Cell system information on BCCH • RRC messages on DCCH

• DCCH and – if configured – DTCH • FACH used for higher layer data transfer, • UE monitors FACH permanently • Uplink transmission on RACH • UE location known on serving cell level • UE performs cell re-selection • UE responsible for measurement reporting • Cell system information on BCCH • RRC messages on BCCH, CCCH and DCCH

CELL_PCH and URA_PCH • • • • •

no DCCH and DTCH Before uplink transmission  UE moves to CELL_FACH UE must be paged RRC messages on BCCH and PCCH In CELL_PCH - UE location known on cell level - UE performs cell re-selection and cell updates • In CELL URA - UE location known on URA level - UE performs cell re-selection and URA updates

What are the characteristics of the individual sub-states, when the UE is in the RRC connected mode? • CELL_DCH In this sub-state, dedicated physical channels are allocated to the UE. DCCH and – if configured – DTCH information can be transmitted. There no need to identify the UE on a dedicated channel, because the physical channels are exclusively allocated to this UE. UTRAN knows the active set cells for the radio links and thus the location of the the UE. Also downlink shared channels can be allocated to the UE. In this state, the UE is capable to receive RRC messages on the DCCH (and BCCH, if it owns specific capabilities). The cell system information is broadcasted on the FACH. The UE reads the cell system information and acts accordingly. For instance, it determines the measurement quality and the reporting events from the cell system information. •

CELL_FACH This state was introduced for traffic situations, where only small amounts of data have to be transmitted. This is the case when only higher layer signalling information (NAS signalling) or small amount of user data (e.g. SMS messages) have to be transmitted. In this case, an exclusive allocation of one physical channel to the UE would result in a waste of resources.

•

The UE is capable to receive and transmit DCCH and – if configured – DTCH information. Only common transport channel FACH can be used by the UE to transmit higher layer data, which it has to share with other UEs. Each UE must be explicitly addressed, for instance by the RNTI. It has to monitor the FACH permanently in the downlink, not to miss user data for it. The UE„s FACH is mapped on one SCCPCH. In the uplink, it uses the shared transport channels for user data transfer, such as the RACH. The UE is only connected to one cell, and this is the location information, known within UTRAN. No soft handover takes place in this substate. The UE is responsible for cell re-selection. By listening to the cell system information from the BCCH, it gains all relevant measurement qualities, threshold values, neighbourhood lists to perform the cell re-selection process. Other relevant information is also learned from the BCCH. The UE receives RRC messages on the BCCH, CCCH and DCCH channels. Due to the discontinuous type of traffic, UTRAN can command the UE to perform periodic cell updates.

•

CELL_PCH In this sub-state, the UE„s current cell is known to the RNC. If the RNC wants to exchange data with the UE, it only needs to page the UE there. If the UE changes the cell, it must perform a cell update. Also periodical cell updates can be requested by UTRAN. To perform updates, the UE must change to the CELL_FACH sub-state. (Please note, that no uplink transmission is allowed in CELL_PCH/URA_PCH.)

•

URA_PCH URA stands for UTRAN Registration Area. If the UE is in the CELL_PCH and moving fast, a lot of cell updates have to be performed. URAs are a combination of one or several cells under one C-RNC. URAs may overlap, i.e. a cell may belong to several URAs. If UTRAN wants to transmit something to the UE, it must page the UE within the URA. The UE is responsible for URA updates – when it changes the URA – and periodic URA updates – when required by UTRAN.

States of Bearer Allocation

System Information Within UTRAN system information is broadcasted with the help of the RRC messages • System Information, • Paging Type I, and • System Information Change Indication. Most system information parameters are determined by the RNC. The Node B is informed about the parameters via the NBAP message BCCH Information. Some system parameters can be made available by the Node B, such as interference values, which change fast. Given the system information, the UE is capable to decide, whether or how to access the PLMN via the existing cell. System information is organised in System Information Blocks (SIBs). System information is grouped into SIB 1 to SIB 18. Each SIB is responsible to carry a specific content. For instance, SIB 12 holds measurement control information and parameters. Depending on the UE„s RRC state, it reads specific SIBs, and uses the transmitted parameters.

There is a huge amount of SIBs, which have to be read by the UE. This requires a lot of battery power. Therefore, a Master Information Block (MIB) was introduced, which gives references and scheduling information about the SIBs. The MIB is transmitted in every 8th radio frame on the P-CCPCH (on position SFN mod 8 = 0, and with a TTI of 20 ms). For most of the SIBs used within the system, the MIB may carry a value tag. The only exceptions are SIB 15.2, SIB 15.3 and SIB 16. If a value tag is unchanged, the corresponding system information has not been modified. Thus, there is no need for the UE to read the SIB. SIB 7 has no value tag. It changes with each occurrence. Scheduling information is used to inform the UE, where and when a specific system information is transmitted.

NBAP = Node B Application Part

System Information ( )

UTRAN

NBAP: BCCH Information

RNC

UE

Node B

MIB value tag M

SIB 1 value tag 1

SIB 2 value tag 2

position on P-CCPCH: SFN mod 8 = 0 TTI: 20 ms value tag M: range 1..8

SIB 3 value tag 3

SIB 18 value tag 18

UTRAN can notify UEs, that a value tag in the MIB has been changed. Hereby, the information element BCCH Modification Info is broadcasted. There are two RRC messages, which can carry this information element: •

•

Paging Type 1 Some mobile phones have no radio link allocated, mobile phones, which are in the RRC idle mode, and in the RRC connected mode sub-states CELL_PCH and URA_PCH. This paging message is transmitted in all paging occasions in the cell. System Information Change Indication With this message, we address UEs in the CELL_FACH sub-state. Consequently, this message must be transmitted on every S-CCPCH, which carries FACHs. The System Information Change Indication message is transmitted on a BCCH, which must be mapped on FACHs in such a way, that every SCCPCH carries the BCCH Modification Change IE.

Within the IE BCCH Modification Change, even a BCCH Modification Time can be given, indicating to the UEs, when the value tags will change. Please note, that UEs in the CELL_DCH sub-state are addressed directly by the RNC via the Measurement Control message.

In this course documentation, we only describe the System Information Blocks (SIBs), which are used in Nokia„s RAN1, and SIB 4 and SIB16. Please note, that all SIBs are valid on cell level except for SIB 1, SIB 15.3, and SIB 16. SIB 1 and SIB 15.3 are valid on PLMN level, while SIB 16 is valid for equivalent PLMNs.

For each SIB, following characteristics were specified: • Area scope: Where is the value tag valid: within one cell or within a PLMN/ equivalent PLMN? • UE RRC state: When the SIB is valid? • UE RRC state: When the SIB is read? • Scheduling information: At which position is the SIB transmitted and what is its repetition period? • Modification of system information: Is it indicated by a value tag, or is it timer based? The UE receives all SIBs via the BCCH. There is only one exception: SIB 10. If a UE is capable to receive simultaneously one SCCPCH and one DPCH, than it receives SIB 10 on a FACH. Master Information Block (MIB): The MIB informs the UE about the supported PLMN types and the PLMN identity. The UE finds in the MIB also references to up to maxSIB (=32) SIBs, including their scheduling information and type. A MIB is valid in one cell. If a UE changes the cell, is must read the new cell„s MIB. The MIB is read in the RRC modes/states RRC idle, CELL_FACH, CELL_PCH and URA PCH. Its parameter are valid in the same states. A change of the MIB information is indicated by a value tag. In this course documentation, we only describe the System Information Blocks (SIBs), which are used in Nokia„s RAN1, and SIB 4 and SIB16. Please note, that all SIBs are valid on cell level except for SIB 1, SIB 15.3, and SIB 16. SIB 1 and SIB 15.3 are valid on PLMN level, while SIB 16 is valid for equivalent PLMNs.

SIB1 System Information Block 1 (SIB 1) This SIB is used to inform the UE about NAS system information. The NAS system information characterises the NAS domains. SIB 1 also delivers UE timers and counters, which have to be used by the UE in the RRC idle and RRC connected mode. For instance, a UE in the RRC connected mode uses the timer T305 for periodic cell and URA updates. SIB 1 is valid in one PLMN. The MIB is read in the RRC modes/states RRC idle, CELL_FACH, CELL_PCH and URA PCH. Its parameter are valid in the same states, and the the RRC sub-state CELL_DCH. If the UE selects a new cell, and the SIB 1 value tag has the same number as in the preceding cell, the same content is transmitted in this SIB. There is then no necessity for the UE to read this SIB after cell re-selection.

T302/N302 The CELL UPDATE/URA UPDATE retransmission timer (MS timer) T300/N300 The RRC CONNECTION REQUEST retransmission timer (MS timer) T312/N312 The timer for supervising successful establishment of a physical channel (MS timer) T309 The timer for supervising successful connection establishment in case of an inter-RAT cell re-selection (MS timer)

T316 This timer is started when the UE detects an out of service area in URA_PCH or CELL_PCH state. This timer is stopped when the UE detects an in service area. When the timer expires the UE initiates cell update procedure (MS timer). T317 This timer is started when the T316 expires and the UE detects an out of service area. This timer is stopped when the UE detects an in service area. When the timer expires the UE transits to idle mode (MS timer)

SIB2

System Information Block 2 (SIB 2) This SIB contains an URA identity list. SIB 2 is read and valid in the RRC sub-state URA_PCH. A change of the SIB 2 information is indicated by a value tag.

SIB3

SIB4

System Information Block 3 (SIB 3) This SIB contains relevant parameters for cell selection and re-selection. It also holds the cell identity and cell restriction data, such as „cell barred“ IEs. SIB 3 must be read and is valid in the RRC idle mode. It is read and valid in the RRC connected mode sub-states CELL_FACH, CELL_PCH and URA_PCH, if SIB 4 is not broadcasted. A change of the SIB 3 information is indicated by a value tag.

System Information Block 4 (SIB 4) This SIB holds mostly the same data fields as SIB 3, but it is read and valid only, when the UE is in the RRC connected mode. I.e, this optional SIB is read and valid in the CELL_FACH, CELL_PACH and URA_PCH substate. A change of the SIB 4 information is indicated by a value tag.

SIB5

System Information Block 5 (SIB 5) The parameters for the configuration of physical channels are broadcasted in this SIB. The parameters cover the PICH power offset, the AICH power offset, P-CCPCH, S-CCPCH and PRACH system information lists. SIB 5 must be read and is valid in the RRC idle mode. It is read and valid in the RRC connected mode sub-states CELL_FACH, CELL_PCH and URA_PCH, if SIB 6 is not available. A change of the SIB 5 information is indicated by a value tag.

SIB7

System Information Block 7 (SIB 7) This SIB holds fast changing parameters. Therefore no value tag is used for it. The UE has to read its parameters periodically. For that, an expiration timer (Expiration Time Factor) is broadcasted with this message. SIB 7 expires at max(32, 8 * Expiration Time Factor). Expiration Time Factor can have the values 2times, 4 times, 8 times ... 256 times. Its default value is 1. The fast changing parameters transmitted with SIB 7 include the UL interference and dynamic persistence level. It is read and valid in all states except for the CELL_DCH sub-state.

SIB11

System Information Block 11 (SIB 11) This SIB holds measurement control information. The UE gets here the relevant date for traffic measurement, intrafrequency measurements, etc. SIB 11 must be read and is valid in the RRC idle mode. It is read and valid in the RRC connected mode sub-states CELL_FACH, CELL_PCH and URA_PCH, if SIB 12 is not broadcasted. It is also valid in the RRC sub-state CELL_DCH, as long as the UE did not get a Measurement Control message from UTRAN and SIB 12 is not broadcasted. A change of the SIB 11 information is indicated by a value tag.

SIB11

SIB11

SIB12

System Information Block 12 (SIB 12) SIB 12 transmits measurement control information for UEs in the RRC connected mode. If not transmitted, the UEs take the parameters broadcasted with SIB 11. If available, SIB 12 is read and valid in the RRC connected mode sub-states CELL_FACH, CELL_PCH and URA_PCH. It is also valid in the RRC sub-state CELL_DCH, as long as the UE did not get a Measurement Control message from UTRAN. A change of the SIB 12 information is indicated by a value tag.

SIB16

System Information Block 16 (SIB 16) RB, TrCH, and PhyCH parameters are broadcasted, which are stored by the UE both in the RRC idle and RRC connected mode. The parameters are used during a handover to UTRAN. Consequently, these parameters stay valid, when the UE is connected to GSM and GPRS. This SIB is valid in all RRC states, and read in all RRC states except for the CELL_DCH. The UE reads and stores the parameters. A change of the SIB 16 information is indicated by a value tag.

RRC messages information - CS

Voice and Video are both Conversational

DL SRB

UE in DUAL MODE

UE in 3G LOCKED MODE

CS call, 64Kbps, Transparent Voice AMR Video Call

Video CS 64: DL SF 32 UL SF 16 Voice AMR: DL SF 128 UL SF 64 (16 Kbps,12.2kbps)

RRC messages information - PS

PS can also be OriginatingHighPrioritySignalling And Registration (Only for Attach)

Modify max bit rate by Nemo

SIM Card QoS profile

Measurement Control (MC) and Measurement Report (MR) UTRAN controls the measurements in the UE, either by broadcasting system information on the BCCH, and/or by transmitting a Measurement Control message on the DCCH. If the UE is in the RRC idle mode, it receives relevant measurement information from the BCCH. The SIB type 3 contains parameters for cell selection and re-selection. In parallel, the SIB type 11 is used to deliver measurement control information to the UE for the serving cell. SIB 3 and SIB 11are read and valid in the RRC idle state. If the UE is in the RRC sub-states CELL_FACH, CELL_PCH and URA_PCH, it is connected to one cell only and responsible for cell selection and re-selection. It retrieves the parameters for cell selection from SIB type 4. The measurement control information is broadcasted with SIB type 12. SIB 4 and SIB 12 are read and valid, when the UE is in the CELL_FACH, CELL_PCH and URA_PCH sub-state. If SIB 4 resp. SIB 12 is not broadcasted, then SIB 3 resp. SIB 11 parameters are used instead. In the sub-state CELL_DCH, the UE is not reading the SIB type 3/4 and 11/12. The parameters of SIB 12 (SIB 11, if SIB is not available) can be still valid in this state. The RRC message Measurement Control can be transmitted to the UE, if a DCCH has been setup between the UE and UTRAN. This message informs the UE about the type of measurement, which has to be conducted. Each measurement command links a measurement with a measurement identity, quantity, objects, reporting quantities, reporting criteria, type, etc.

I am in the RRC idle mode

I am in the CELL_FACH, CELL_PCH or URA_PCH sub-state

I am in the CELL_DCH sub-state

UE

System Information [BCCH] SIB 3 & SIB 11

UTRAN Node B

UE

System Information [BCCH] SIB 4 & SIB 12 (SIB 3 & SIB 11)

RNC

UTRAN Node B

UE

Measurement Control [DCCH]

UTRAN

Node B SIB 3 [4]: parameters for cell selection and re-selection [in the RRC connected mode] SIB 11 [12] : measurement control information [in the RRC connected mode] read and valid: idle, CELL_FACH, CELL_PCH, URA_PCH. (SIB 11/12 is also valid in the CELL_DCH.)

RNC

RNC

Measurement Control (MC) and Measurement Report (MR) How does a UE perform measurements after a transition in the CELL_DCH state. Two cases have to be distinguished: Transition from the RRC idle state to the CELL_DCH sub-state In the RRC idle state, the UE retrieved the measurement control parameters from the SIB type 11. Information Elements, which contain intra-frequency, inter-frequency, inter-RAT and traffic volume measurement system information, may be included in the SIB 11. If they are included, the UE can send a measurement report, when a measurement reporting criteria is fulfilled. As soon as the UE receives a Measurement Control message including one of the above mentioned measurement types, it replaces its internal stored data based on the SIB11 by the parameters delivered with the Measurement Control message. Transition from the CELL_FACH to the CELL_DCH sub-state. In the CELL_FACH sub-state, the SIB 12 (or SIB 11, if there is no SIB 12) is valid including all relevant measurement control parameters. If the UE transits to the CELL_DCH sub-state, the system information stays valid, as long as there was no Measurement Control message, which replaces the parameters. But what happens, if the UE was in the CELL_DCH sub-state, it has received Measurement Control messages, and it then transits to the CELL_FACH sub-state. In the CELL_FACH sub-state, the UE reads SIB 12 (SIB 11), and its measurement control parameters become valid. But when the UE then transits back to the CELL_DCH sub-state, the UE resumes with the measurements and associated reporting, as they were stored before the transition to the CELL_FACH (or any other RRC connected) sub-state.

Measurement Control (MC) and Measurement Report (MR) The RRC message Measurement Control is used to setup, to modify, and to release a measurement in the UE. The UE gets all relevant information, how to perform a specific type of measurements. A measurement is either conducted periodically or driven by an event. Then, the UE returns a measurement report. The Measurement Control message is transmitted on a DCCH via an RLC entity in the acknowledged mode. I.e. the UE is either in the RRC connected sub-state CELL_DCH or CELL_FACH. If the setup of a measurement fails, the UE returns the RRC message Measurement Control Failure. It is transmitted on an UL DCCH via an RLC entity in the acknowledged mode. The RRC message Measurement Report was specified to deliver measurement results from the UE to UTRAN (RNC). This message is transmitted on a DCCH. The RLC entity can be in the acknowledged or unacknowledged mode. The RLC entity mode is set by the RRC message Measurement Control. Measurement results can be only transmitted in the CELL_DCH or CELL_FACH sub-state. CELL_DCH: If a reporting criterion is met, the UE transmits a Measurement Report. A measurement identity identifies the measurement as specified by UTRAN. It includes measurement quantities and identifies the measurement event. CELL_FACH: In this sub-state, traffic volume measurements and positioning measurements are reported by the UE. Intra-frequency measurements are reported via the RACH, whereby the UE learns from the BCCH (SIB11 or SIB12) the maximum numbers of cells, it can report. CELL_PCH or URA_PCH: UE must perform a cell update. Cell update cause is „uplink data transmission“. Then they are in the CELL_FACH state, where the Measurement Report can be sent. The measurement report either holds traffic volume measurements or positioning measurements.

Measurement Control (MC) and Measurement Report (MR) With the RRC message Measurement Control, UTRAN commands the UE to perform measurements on its behalf. There is a set of different types of measurements, which can be conducted: • Intra-Frequency Measurements • Inter-Frequency Measurements • Inter-RAT Measurements • UE-Internal Measurements • Traffic Volume Measurements • Quality Measurements • UE Positioning Methods As a consequence, a UE may be forced to conduct several different types of measurements simultaneously. Each type of measurement is identified by an allocated „Measurement Identity“. Some measurements are not conducted continuously. UTRAN tells the UE once, how to perform a type of measurements. Whenever necessary, it just informs the UE to conduct the measurements of a measurement type by just telling it the associated measurement identity. Each measurement type comes with a measurement command: setup, modify, and release.

Finally, UTRAN inform the UE, how to deliver the measurement reports: Delivery on an acknowledged or unacknowledged RLC, and Periodical or event triggered reporting. In the RRC message Measurement Control, the is an PhyCH information elements, where the UE can gain DPCH compressed mode status information.

Measurement Control ( ) RNC

UE

UE IEs Measurement IEs

Measurement Identity Measurement Command

PhyCH IEs Measurement Reporting Mode Additional measurements list

CHOICE Measurement type DPCH compressed mode status info

setup/modify/release RLC AM/UM and periodical reporting/event triggered includes non-frequency related cell info

Intra-Frequency Measurements Inter-Frequency Measurements Inter-RAT Measurements UE-Internal Measurements Traffic Volume Measurements Quality Measurements UE Positioning Methods

RRC messages information UL Traffic volumes High threshold information sent after RAB setup complete (CELL_DCH)

RRC messages information

UE Buffer triggers Threshold for RAB Upgrade


First RAB Reconfiguration DL 32Kbps(SF64)/ UL 32Kbps SF32)

RRC messages information UL Traffic volumes High threshold information sent after RAB setup complete (CELL_DCH)

RRC messages information Maximum DL bit rate for PS domain NRT data = 384 Kbps Maximum UL bit rate for PS domain NRT data = 64 Kbps Initial and minimum allowed bit rate in downlink = 32 Kbps Initial and minimum allowed bit rate in uplink = 32 Kbps Second RAB Reconfiguration DL 384Kbps(SF8)/ UL 32Kbps (SF32)


Cell DCH  Cell FACH


Cell FACH  Cell PCH


Cell PCH  Cell FACH


Cell FACH  Cell DCH

Intra-frequency Measurements Intra-frequency measurements are measurements on downlink physical channels at the same frequency as the active set.“ The measurement object is one cell. If the RRC message Measurement Control commands the UE to make intra-frequency measurement, it may contain among others: Intra-frequency cell info list (optional) Measurement quantity There are three different measurement quantities for the FDD mode: - Downlink Ec/N0 - Downlink received signal code power (RSCP) after despreading. - Downlink pathloss in dB = Primary CPICH Tx power - CPICH RSCP. Measurement validity The measurement validity describes, when the measurement has to be conducted. There are three options: - CELL_DCH state, - all states except the CELL_DCH state, and - all states. Reporting Criteria Reporting criteria outline, what kind of intra-frequency measurements have to be conducted. A set of intrafrequency measurements were specified, but it is the operator„s choice, which ones are used.

Intra-frequency Reporting Events Below, you can see a list of intra-frequency reporting events. UTRAN decides, which of the listed events have to be reported by the UE. The required intra-frequency reporting events, which are choosen by UTRAN, depend on the implemented handover reporting function or other radio network functions. The measurement quantities are determined by measuring the P-CPICH of the cell. Reporting events 1A: A Primary CPICH enters the reporting range The reporting range can be between 0 and 14.5 dB (step size 0.5 dB). The reporting range can be set in relation with the measurement of the best (strongest) cell – as is was displayed on the next figure. It can be also set in ration with a weighted average of the best measured cell and the averaged measurement results of additional, non-forbidden cells. If a CPICH crosses the reporting range, a reporting event is triggered. A individual cell offset can be taken into account. 1B: A primary CPICH leaves the reporting rang Similar concept as in 1A. 1C: A non-active primary CPICH becomes better than an active primary CPICH 1D: Change of best cell 1E: A Primary CPICH becomes better than an absolute threshold (RAN 1.5) Inter-rat 1F: A Primary CPICH becomes worse than an absolute threshold (RAN 1.5) A hysteresis value can be set before reporting the event in all reporting events – in the figures, this is only shown for 1A and 1B.

Intra-frequency Reporting Events

Intra-frequency Reporting Events

e.g. P-CPICH Ec/No

Intra-frequency Reporting Events Reporting event: 1E: A P-CPICH becomes better than an absolute threshold 1F: A P-CPICH becomes worse than an absolute threshold

Cell 1

Cell 2

Cell 3

absolute threshold

1F for cell 1 1E for cell 3

time

Neighbourhood List Combination for Intra-frequency HOs Two Cells in the Active Set

Cell 2

Cell 1

Cell 6

Cell 5

Cell 9

Cell 3

Cell 10

Cell 4

Cell 7

Cell 11

Cell 8 Neighbour cells defined only for Cell 7 Cell 12

Cell 3 Cell11 Neighbour cells which are common to Cell 6 and Cell 7 Neighbour cells defined only for Cell 6

Cell 2

Cell 4

Cell7

Cell 8

Cell 10

Cell 12

Cell 5

Cell 6

Neighbourhood List Combination for Intra-frequency HOs Cell 2

Cell 15

Cell 1

Cell 5

Cell 21

Cell 2

Cell 7

Cell 2

Cell 3

Cell 9

Cell 7

Cell 7

Cell 11

Cell 37

Cell 11

Cell 15

Cell 51

Cell 50

Cell 48

Cell 49

Cell 9

Cell 4

Cell 9

Cell 13

Cell 41

Cell 10

Cell 10

Cell 6

Cell 56

Cell 22

..

…

…

...

...

...

Cell 43

Cell 25

Cell 33

Step 2 Common to 3 Neighbour Lists

Cell2 Common to 2 Neighbour Lists

Cell 7 Cell 9 Cell 11

Step 3

Cell 15 Cell 10 Cell 37

Step 1

Cell 41

Neighbour Cells Lists

Cell 49 Three Cells in the Active Set

Step 4

Neighbour Cells defined for only 1 Neighbour List: random selection

….. … Cell 22

Max 32 Cells

CS and PS Call Flow Cell Search When a UE is switched on, it starts to monitor the radio interface to find a suitable cell to camp on. But it has to determine, whether there is a WCDMA cell nearby. If a WCDMA cell is available, the UE has to be synchronised to the downlink transmission of the system information – transmitted on the physical channel P-CCPCH – before it can make a decision, in how far the available cell is suitable to camp on. Initial cell selection is not the only reason, why a UE wants to perform cell synchronisation. This process is also required for cell re-selection and the handover procedure. Cell synchronisation is achieved with the Synchronisation Channel (SCH). This channel divides up into two sub-channels: P-SCH and S-SCH With the help of the SCH, the UE was capable to perform chip, TS, and frame synchronisation. Even the cell„s scrambling code group is known to the UE. The UE knows the cell„s primary scrambling code. It now wants to gain the cell system information, which is transmitted on the physical channel P-CCPCH. The channelisation code of the P-CCPCH is also known to the UE, because it must be Cch,256,1 in every cell for every operator. By reading the cell system information on the P-CCPCH, the UE learns everything about the configuration of the remaining common physical channels in the cell, such as the physical channels for paging and random access.

RAB 1st then RRC

MOS CS Message Flow UE

NodeB

RNC

MGW/CN

RRC: RRC Connection Request (RACH) T300=2s ; N300=3

NBAP: Radio Link Setup Request

RNC checks if resources are available: BTS, AC, Transmission. If not it sends RRC Connection Reject

NBAP: Radio Link Setup Response ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm) FP: Downlink Synch FP: Uplink Synch RRC: RRC Connection Setup (FACH)

L1 Synchronization

[RRCconnRepTimer1/2(100ms,1s)]

L1 Synchronization NBAP: Synchronization Indication RRC: RRC Connection Setup Complete (DCH)

RRC Connection Establishment – CELL DCH State

T312=6s ; N312=4

RRC: Initial Direct Transfer (MM: CM Service Request)

SCCP: CR (Connection Request)

RRC Connection till the RNC

RANAP: Initial UE Message (MM: CM Service Request) SCCP: CC (Connection Confirm)

RANAP: Direct Transfer (MM: Authentication Request) RRC: Downlink Direct Transfer (MM: Authentication Request) RRC: Uplink Direct Transfer (MM: Authentication Response) RANAP: Direct Transfer (MM: Authentication Response) RANAP: Common ID RANAP: Security Mode Command RRC: Security Mode Command

UE

NodeB

RNC

MGW/CN

RRC: Security Mode Complete RANAP: Security Mode Complete RRC: Uplink Direct Transfer (CC: Setup) RRC: Downlink Direct Transfer (CC: Call Confirmed)

RAB Establishment

NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm)

RANAP: Direct Transfer (CC: Setup)

RANAP: Direct Transfer (CC: Call Confirmed) RANAP: RAB Assignment Request

RL modification procedure: SRB+DCH, HW resources checked Possible failure in AAL2 setup (Iub, Iur and Iu)

FP: Downlink Synch FP: Uplink Synch ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm) NBAP: Radio Link Reconfiguration Commit) RRC: Radio Bearer Setup

Soft handover is not allowed during the RAB establishment procedure (The mobile can not add or remove cells in AS) this makes the UE and Node B particularly sensitive to mobility and dominance Timer wf_rb_setup_cpl (6s) is started when the RRC: Radio Bearer Setup message is sent to the UE In case the timer expires Iu Release Request is sent to the CN with release cause (radio_conn_lost) RRC: Radio Bearer Setup Complete RANAP: RAB Assignment Response

UE

NodeB

RNC

MGW/CN

RANAP: Direct Transfer (CC: Alerting) RRC: Downlink Direct Transfer (CC: Alerting) RANAP: Direct Transfer (CC: Connect) RRC: Downlink Direct Transfer (CC: Connect) RRC: Uplink Direct Transfer (CC: Connect Acknowledge) RANAP: Direct Transfer (CC: Connect Acknowledge)

Call Established RANAP: Location Report RRC: Measurement Control

Call Disconnect RRC: Uplink Direct Transfer (CC: Disconnect) RANAP: Direct Transfer (CC: Disconnect) RANAP: Direct Transfer (CC: Release) RRC: Downlink Direct Transfer (CC: Release) RANAP: Direct Transfer (CC: Release Complete) RANAP: Iu Release Command RANAP: Iu Release Complete RRC: Downlink Direct Transfer (CC: RRC Connection Release) RRC: Uplink Direct Transfer (CC: RRC Connection Release Complete) RRC: Uplink Direct Transfer (CC: RRC Connection Release Complete) RRC: Uplink Direct Transfer (CC: RRC Connection Release Complete) NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm)

MTC CS Message Flow NodeB

UE

MGW/CN

RNC RANAP: Paging

RRC: Paging Type 1

RRC: RRC Connection Request (RACH) NBAP: Radio Link Setup Request NBAP: Radio Link Setup Response ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm) FP: Downlink Synch FP: Uplink Synch

L1 Synchronization

RRC: RRC Connection Setup (FACH) L1 Synchronization NBAP: Synchronization Indication RRC: RRC Connection Setup Complete (DCH)

RRC Connection Establishment – CELL DCH State RRC: Initial Direct Transfer (MM: Paging Response) SCCP: CR (Connection Request) RANAP: Initial UE Message (MM: Paging Response) SCCP: CC (Connection Confirm) RANAP: Direct Transfer (MM: Authentication Request)

RRC: Downlink Direct Transfer (MM: Authentication Request) RRC: Uplink Direct Transfer (MM: Authentication Response) RANAP: Direct Transfer (MM: Authentication Response) RANAP: Common ID RRC: Security Mode Command

RANAP: Security Mode Command

UE

NodeB

RNC

MGW/CN

RRC: Security Mode Complete RANAP: Security Mode Complete RRC: Uplink Direct Transfer (CC: Setup) RRC: Downlink Direct Transfer (CC: Call Confirmed)

RAB Establishment

NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm)

RANAP: Direct Transfer (CC: Setup)

RANAP: Direct Transfer (CC: Call Confirmed) RANAP: RAB Assignment Request

RL modification procedure: SRB+DCH, HW resources checked Possible failure in AAL2 setup (Iub, Iur and Iu)

FP: Downlink Synch FP: Uplink Synch ALCAP: ERQ (Establish Request) ALCAP: ECF (Establish Confirm) NBAP: Radio Link Reconfiguration Commit) RRC: Radio Bearer Setup

Soft handover is not allowed during the RAB establishment procedure (The mobile can not add or remove cells in AS) this makes the UE and Node B particularly sensitive to mobility and dominance Timer wf_rb_setup_cpl (6s) is started when the RRC: Radio Bearer Setup message is sent to the UE In case the timer expires Iu Release Request is sent to the CN with release cause (radio_conn_lost) RRC: Radio Bearer Setup Complete RANAP: RAB Assignment Response

UE

NodeB

RNC

RRC: Downlink Direct Transfer (CC: Alerting)

MGW/CN RANAP: Direct Transfer (CC: Alerting) RANAP: Direct Transfer (CC: Connect)

RRC: Downlink Direct Transfer (CC: Connect) RRC: Uplink Direct Transfer (CC: Connect Acknowledge) RANAP: Direct Transfer (CC: Connect Acknowledge)

Call Established RANAP: Location Report

RRC: Measurement Control

MOS PS Message Flow UE

NodeB

RNC

RRC: RRC Connection Request (RACH)

NBAP: Radio Link Setup Request NBAP: Radio Link Setup Response AAL2SIG: ERQ AAL2SIG: ECF FP: Downlink Synch FP: Uplink Synch RRC: RRC Connection Setup (FACH)

SGSN RNC checks if resources are available: BTS, AC, Transmission. If not it sends RRC Connection Reject L1 Synchronization

[RRCconnRepTimer1/2(100ms,1s)]

L1 Synchronization NBAP: Synchronization Indication

RRC: RRC Connection Setup Complete (DCH)

RRC Connection Establishment – CELL DCH State RRC: Initial Direct Transfer (MM: Attach Request) RANAP: Initial UE Message MM: (Attach Request) RRC: Downlink Direct Transfer (MM: GPRS Identity Request)

RANAP: Direct Transfer (MM: GPRS Identity Request)

RRC: Uplink Direct Transfer (MM: GPRS Identity Response)

RANAP: Direct Transfer (MM: GPRS Identity Response) RANAP: Direct Transfer (MM: Authentication & Ciphering Request) RRC: Downlink Direct Transfer (MM: Authentication & Ciphering Request) RRC: Uplink Direct Transfer (MM: Authentication & Ciphering Response) RANAP: Direct Transfer (MM: Authentication & Ciphering Response) RRC: Security Mode Command

RANAP: Security Mode Command

RRC: Security Mode Complete RANAP: Security Mode Complete RANAP: Common ID


NodeB

RNC

SGSN

RANAP: Direct Transfer (MM: Attach Accept)

RRC: Downlink Direct Transfer (MM: Attach Accept) RRC: Uplink Direct Transfer (MM: Attach Complete)

RANAP: Direct Transfer (MM: Attach Complete) RRC: Uplink Direct Transfer (SM: Activate PDP Context Request) RANAP: Direct Transfer (SM: Activate PDP Context Request)

RAB Establishment SRB + DCH 0/0

RRC: Radio Bearer Setup RRC: Radio Bearer Setup Complete

RANAP: RAB Assignment Request

RANAP: RAB Assignment Response


RANAP: Direct Transfer (SM: Activate PDP Context Accept)

RRC: Downlink Direct Transfer (SM: Activate PDP Context Accept) RRC: Measurement Repor (Trafic Volume Reports 4a) NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready AAL2SIG: ERQ AAL2SIG: ECF NBAP: Radio Link Reconfiguration Commit

RRC: Radio Bearer Reconfiguration RRC: Radio Bearer Reconfiguration Complete

Uplink & Downlink Data Transfer

RL modification procedure: SRB+DCH, HW resources checked


NodeB

RNC

SGSN

RRC: Uplink Direct Transfer (SM: Deactivate PDP Context Request)

RRC: Downlink Direct Transfer (SM: Deactivate PDP Context Accept)

RANAP: Direct Transfer (SM: Deactivate PDP Context Request) RANAP: Direct Transfer (SM: Deactivate PDP Context Accept)

NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready AAL2SIG: ERQ AAL2SIG: ECF NBAP: Radio Link Reconfiguration Commit RRC: Uplink Direct Transfer (MM: Detach Request)

RANAP: Direct Transfer (MM: Detach Request)

RRC: Radio Bearer Release RANAP: Direct Transfer (MM: Detach Accept) RRC: Downlink Direct Transfer (MM: Detach Accept) RANAP: Iu Release Command RANAP: Iu Release Complete RRC: Radio Bearer Release Complete RRC: RRC Connection Release RRC: RRC Connection Release Complete RRC: RRC Connection Release Complete RRC: RRC Connection Release Complete

NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response AAL2SIG: REL (Release Request) AAL2SIG: RCL (Release Confirm)

RRC setup

Bearer setup

Real traffic transfer

9:52:53 : C09 AMR

Soft Handover

Handover Types •

•

Intra-Frequency Handovers –

Softer Handover • Handover between sectors of the same Node B (handled by BTS) • No extra transmissions across Iub interface • Maximum Ratio Combining (MRC) is occurring in both the UL and DL

–

Soft Handover • MS simultaneously connected to multiple cells (from different Node Bs) • Extra transmission across Iub, more channel cards are needed (compared to non-SHO) • Mobile Evaluated Handover (MEHO) • DL/UE: MRC & UL/RNC: Frame selection combining

–

Hard Handover • Arises when inter-RNC SHO is not possible (Iur not supported or Iur congestion) • Decision procedure is the same as SHO (MEHO and RNC controlled) • Causes temporary disconnection of the (RT) user

Inter-Frequency Handover – – –

•

Can be intra-BS, intra-RNC, inter-RNC Network Evaluated Handover (NEHO) Decision algorithm located in RNC

Inter-RAT Handover –

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Handovers between GSM and WCDMA (NEHO)

© 2006 Nokia

SHO: Neighbour Cell Definition •

Each intra-frequency neighbour (ADJS) is identified using ADJSid (ADJS)

•

The ADJS parameters provide information on the identity of each neighbour cell together with its properties (i.e. Handover parameter set identifier, scrambling code etc..)

•

Each neighbour cell is defined using the UTRAN cell identifier which comprises

UTRAN Cell Identifier = MCC + MNC + RNC identifier + Cell identifier

• Each neighbor cell is defined using the UTRAN cell identifier which comprises; MCC (Mobile Country Code) MNC (Mobile Network Code) RNC Identifier Cell Identifier

= AdjsMCC = AdjsMNC = AdjsRNCid = AdjsCI

ADJS Parameters

• The LAC (AdjsLAC) & RAC (AdjsRAC) are also in ADJS parameter set

Maximum number of neighbours

• The maximum number of neighbours that can be defined in RNC database is – ADJS: 31 • 31 neighbours + serving cell = 32 cells to measure – ADJI: 32/carrier, total 48 – ADJG: 32 • Total: max. 111 in RNC database • Limitation due to specifications of SIB11/12 size

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Soft Handover • HC supports the following measurement reporting events and features: – Event 1A: A primary CPICH enters the reporting range (Ncell addition) – Event 1B: A primary CPICH leaves the reporting range (Ncell deletion) – Event 1C: A non-active CPICH becomes better than an active primary CPICH (Ncell replacement) – Cell individual offsets for modifying measurement reporting behaviour – Mechanism for forbidding a neighbor ing cell to affect the reporting range

• Handover decision performed by RNC based on measurements and available resources • Admission Control can reject the branch addition in case the maximum load is achieved in DL (threshold + offset), valid both for RT and NRT bitrates. • Hard blocking may prevent branch addition

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1A: A Primary CPICH Enters the Reporting Range ActiveSetWeightingCoefficient Strongest CPICH in AS

Ec/Io

P CPICH 1

P CPICH 2

AdditionWindo w 1 2

P CPICH 3 time AdditionTime

3

Measurement Report

no

AdditionReportingInterval 4

Add to the AS? 130

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RNC

1B: A Primary CPICH leaves the Reporting Range

Ec/Io

Strongest CPICH in AS P CPICH 1 P CPICH 2

2

DropWindow

1 P CPICH 3

3 time

DropTime Measurement Report 133

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Remove the reported cell from the AS

Soft and Softer Handover (case1) • SIB 11 contains the relevant parameters to read when in idle mode • These are valid in connected mode prior to receiving the measurement control that overwrites them • In this example: • Addition window= 2 dB (factor of 2 mapping between the signalled value and the actual value, TS 25.331 defines this mapping) • Addition time = 100 ms • Reporting interval = 500 ms • Drop window = 3 dB (factor of 2 mapping between the signalled value and the actual value) • Drop time = 640 ms

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Extract from SIB 11 reportCriteria intraFreqReportingCriteria : { eventCriteriaList { { event e1a : { triggeringCondition monitoredSetCellsOnly, reportingRange 4, w 0, reportDeactivationThreshold t2, reportingAmount ra-Infinity, reportingInterval ri0-5 }, hysteresis 0, timeToTrigger ttt100, reportingCellStatus allActiveplusMonitoredSet : viactCellsPlus2 } event e1b : { triggeringCondition activeSetCellsOnly, reportingRange 6, w0 }, hysteresis 0, timeToTrigger ttt640, reportingCellStatus withinActiveSet : e3 },

1C: A non-active CPICH becomes better than an active primary CPICH AS has 3 cells

Ec/Io

P CPICH 1 P CPICH 2 P CPICH 4 1 ReplacementWindow P CPICH 3

weakest CPICH3 in AS

time 2

3 ReplacementTime ReplacementReportingInterval no

Measurement Report 137

© 2006 Nokia

AS update? RNC

Soft and Softer Handover (case 2) Extract from SIB 11 cont. •

In this example: –

Replacement window = 1 dB

–

Replacement time = 100 ms

–

Reporting interval = 500 ms

–

Replacement window requires mapping to its true value according to: 4/(2*2) = 1 dB

• •

• •

138

event e1c : { replacementActivationThreshold t3, reportingAmount ra-Infinity, reportingInterval ri0-5 }, hysteresis 4, timeToTrigger ttt100, reportingCellStatus withinActiveSet : e3 }

There are two mappings – first is the signalled value to actual value mapping and second is the way in which hysteresis is applied in the event triggering equation (TS25.331) Once in connected mode the networks sends the same set of information elements via a measurement control message Nokia‟s implementation is that the values in the measurement control message are the same as those within SIB 11 Events 6F and 6G are configured in a similar fashion i.e. within SIB 11 and subsequently with a measurement control message

© 2006 Nokia

Individual Ncell Offset Ec/Io

P CPICH 1

Reportin g Range

P CPICH 2

AdjsEcNoOffset

Enlarging Cell 3 by x dB P CPICH 3 time Reporting Event 1B 140

© 2006 Nokia

Reporting Event 1A

Forbidding Neighbour Cell from Reporting Range Ec/Io

P CPICH 1 Reporti ng Range P CPICH 2

PCPICH3 is forbidden to affect the reporting range as its quality is quite unstable.

AdjsDERR

P CPICH 3

Time 141

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Soft Handover signalling Branch addition

Branch deletion RRC: Measurement Report (e1b)

RRC: Measurement Report (e1a) RRC: Active Set Update RRC: Active Set Update RRC: Active Set Update Complete RRC: Active Set Update Complete

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SHO Summary Event

Reporting cell status

Triggering Condition

Reporting Range/ Time to Trigger Hysteresis

Active set cells + Event 1A Monitored set 2 monitored set (Add) cells cells

Event 1B Active set cells Active set cells (Drop)

Active set cells + Event 1C 2 monitored set (Replace) cells

• •

-

Addition Window/4 dB

Drop Window/ 6 dB

Replacement Window/2 dB

Addition Time /100 ms

Addition Reporting Interval /0.5 s

Drop time /640 ms

-

Replacement time/100 ms

Replacement Reporting Interval/ 0.5s

3GPP reporting events 1A, 1B and 1C (also 6F and 6G) CPICH Ec/Io is used as a measurement quantity rather than CPICH RSCP – CPICH Ec/Io measurements are more accurate

• •

Reporting Interval

1A and 1B reporting range is defined by strongest active set cell 1C reporting range is defined by weakest active set cell 143

© 2006 Nokia

RRC Connection Release • •

If difference between the best AS cell and the NS cell is too high and SHO is not performed, the RRC connection is released to avoid excessive interference Why might an AS update not be possible? – – – –

Excessive load in the neighbor ing cell Hard blocking in the target BTS Unavailability of DL spreading codes Iub transport resources unavailable

•

This function is activated by EnableRRCRelease (HOPS parameter)/0=no (def),1 =yes

•

The RRC connection is released if either: AveEcNoDownlink + ReleaseMarginForAveEcNo(n) < AvEcNoNcell(n) EcNoDownlink + ReleaseMarginPeakEcNo(n) < EcNoNcell(n) – –

•

144

ReleaseMarginForAveEcNo (HOPS) = average Eb/N0 margin [-6 … 6] dB, default 2.5dB ReleaseMarginPeakEcNo (HOPS) = peak Eb/N0 margin [-6 … 6] dB, default 3.5dB

Emergency calls are exempt from RRC Connection Release process

© 2006 Nokia

Inter-RNC Mobility • • •

Most of the times the UE hands over among WBTS belonging to the same RNC (Intra-RNC Handovers) However, what happens when the target WBTS is under a different WBTS?? 3GPP gives two different options to handle inter-RNC mobility in WCDMA – Anchoring: the UE will be connected to the CN via the “old” RNC. It is required Iur connection between the RNCs involved – SRNS relocation: the UE will be connected to the CN via the “new” RNC. It is the Nokia implemented method

Anchoring

SRNS relocation *) Iu RNC

Iu

Iu Iur

RNC

RNC

Iu

Iu Iur

RNC

*) SRNS relocation needs core network support; UE support mandatory in 3GPP

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CN

CN

CN

CN

RNC

Iu

Iu Iur

RNC

RNC

Iu Iur

RNC

UE not involved SRNC Relocation for RT RelocationSupport =1

NrncRelocationSupport =1 Source RNC

Target RNC

CN

UE

SRNC Relocation Decision RANAP:Relocation Required

•

RANAP:Relocation Request

Start RelocPrep

Start RelocOverall RANAP:Relocation Request Ack

•

User plane set-up

Stop RelocPrep

•

RANAP:Relocation Command

Start RelocOverall

•

RNSAP:Relocation Commit

SRNC operation started

•

RANAP:Relocation Detect

UP switching

RRC:UTRAN Mobility Information RRC:UTRAN Mobility Information Confirm

Stop RelocOverall

RANAP:Relocation complete

RANAP:Iu Release

Stop RelocOverall RANAP:Iu Release Complete

User plane release

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•

SRNC Relocation is initiated in the Serving RNC when all the cells of the active set belong to a different RNC. The SRNC sends a Relocation Required The CN evaluates if the relocation is possible and in that case, it sends a Relocation Request to the target RNC with parameters for the bearer establishment Relocation Command sent from CN to Source RNC with UTRAN information and bearer parameters After that, the Source RNC sends Relocation Commit message over Iur to the Target RNC When target RNC starts to act as Serving RNC, it sends a Relocation Detect message to CN. This message has no parameters At the same time UTRAN Mobility Information is sent to the UE, to inform that the relocation is performed After the confirm, the target RNC informs CN with Relocation Complete –message that the relocation procedure was successful and Iu is released from source RNC

UE involved: Combined SRNC Relocation and inter-RNC HHO for RT RelocationSupport =1

NrncRelocationSupport =1 Source RNC

Target RNC

CN

UE

SRNC Relocation Decision

•

RANAP:Relocation Required RANAP:Relocation Request

Start RelocPrep

Start RelocOverall

•

RANAP:Relocation Request Ack

•

User plane set-up

Stop RelocPrep RANAP:Relocation Command

Start RelocOverall

Physical Channel Reconfiguration L1 sync. Established between BTS and UE RANAP:Relocation Detect

UP switching Physical Ch Reconfig Complete RANAP:Relocation complete

Stop RelocOverall RANAP:Iu Release

Stop RelocOverall RANAP:Iu Release Complete

User plane release

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•

Because there is no Iur interface, combined SRNS relocation and HHO are done before the UE is completely under the target RNC The procedure is quite similar to the not UE involved case until Relocation Command The only difference in the Relocation Required message, the Relocation Type IE is set to "UE involved in relocation of SRNS" Instead of Relocation Commit via Iur, the serving RNC sends a Physical CH Reconfiguration, after which the UE stops transmitting and receiving on the old radio links and starts on the new radio link

Inter-system Handover (ISHO)

ISHO Inter System Handover 3G -> 2G RAN Internal measurements

Configured UE measurements

UL Quality deterioration

Downlink DPCH power

UE Tx power

Initiate Compressed Mode Configure GSM measurements UE Reports GSM RSSI measurements

GSM Cell Meets HO condition ? CS

PS

General

Initiate Compressed Mode Configure GSM measurements UE Reports GSM BSIC measurements Initiate Handover

CPICH RSCP

CPICH Ec/I0

ISHO parameters CPICH RSCP (Event 1F) •Thresholds: HHoRscpThreshold HHoRscpCancel L3 filter: HHoRscpFilterCoefficient •Timers: HHoRscpTimeHysteresis HHoRscpCancelTime

UE Tx Power (Event 6A) •Threshold: GsmUETxPwrThrXX •L3 filter: GsmUETxPwrFilterCoeff •Hysteresis margin: GsmUETxPwrTimeHyst •Data rate threshold HHOMAxAllowedBitrateUL

CPICH Ec/Io (Event 1F) •Thresholds: HHoEcNoThreshold HHoEcNoCancel •L3 filter: Done already for SHO •Timers: HHoEcNoTimeHysteresis HHoEcNoCancelTime

DL DPCH power •Threshold: GsmDLTxPwrThrXX •Data rate threshold HHOMAxAllowedBitrateDL

GSM measurement reporting GsmMeasRepInterval GsmNcellSearchPeriod GsmMinMeasInterval GsmMaxMeasPeriod

UL Quality •Timer: ULQualDetRepThreshold •Data rate threshold HHOMAxAllowedBitrateUL

Handover Triggering (XX=AMR,CS,NrtPS,RtPS)

Decision Algorithm AdjgTxPwrMaxTCH AdjgRxLevMinHO (n) GsmMeasAveWindow

2 more optional triggers in RAN04:

IMSI based ISHO Emergency ISHO (EMISHO) 150

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Handover Execution

2G-to-3G back prevention GsmMinHoInterval

Measurement Control Parameters: FMCG •

Maximum allowed duration of the inter-system measurement is calculated: – GSMMeasRepInterval * GSMMaxMeasPeriod (=0.5*20s) =10s,

•

•

This seems to be too long time, because based on field measurements BSIC and RSSI delays are about 3 seconds, so it makes senses to reduce the value of this parameter to some value about 3 seconds, otherwise, if the BSIC or RSSI measurements fail or if the IS-HO execution is not possible to due low GSM RSSI levels, the network will not deactivate compressed mode until the timer of 10 seconds has expired. Thus, decreasing the parameter value will allow the UE/network to initiate a new IS-HO attempt. Proposed value for GSMMaxMeasPeriod is 6 GSMNcellSearchPeriod: 0 – This is neighbor cell search period parameter, ISHO is not allowed until the are enough measurement reports given by this parameter – O means that only 1 measurement result is enough for decision making – Duration of the cell search period is calculated: – GSMRepInterval * GSMNcellSearchPeriod).

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ISHO Process Overview HO Triggering Thresholds set in RNC

About 25 HO parameters

Event Triggered Coverage/Capacity based HO fulfilled in RNC

5 Coverage/Capacity HO Reasons

RNC commands selected UE(s) to start IF/IS measurements

(31 Intra-Freq neighbours) 48 Inter-Freq neighbours 32 Inter-System neighbours can be measured

Measurements are done in Compressed Mode (CM) UE reports GSM cells with strongest RSSI signals to RNC

Max 32 neighbours could be measured

RSSI measurements and BSIC verification for GSM cells

Reporting cells are active set cells (max 3) + max 6 IFHO, max 6 ISHO neighb.

RNC makes HO decision and commands UE to target cell

Different decision methods for IF HO Only one decision method for IS HO

ISHO 3G -> 2G - AMR Signalling Flow Node B

U E RRC: Measurement Report

RNC RRC: Measurement Control

NBAP: Radio Link Reconfiguration NBAP: Radio Link ReconfigurationPrepare Ready NBAP: Radio Link Reconfiguration RRC: Physical Channel Reconfiguration Complete

RRC: Measurement Report

Commit RRC: Physical Channel Reconfiguration NBAP: Compressed Mode Command RRC: Measurement Control NBAP: Compressed Mode Command RRC: Measurement


Control

CN

ISHO triggering (2 reasons are possible) Initial Compressed Mode Configuration

GSM RSSI Measurem ent GSM BSIC Identification RANAP: Relocation Required

RRC: Handover from UTRAN Command

RANAP: Relocation Command RANAP: IU Release Command RANAP: IU Release Complete

• 153

BSIC verification always performed for AMR calls – no interrupt in voice call © 2006 Nokia

ISHO 3G -> 2G - PS Signalling Flow U E

Node B


CN

RNC RRC: Measurement Control

NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready NBAP: Radio Link Reconfiguration Commit RRC: Physical Channel Reconfiguration

ISHO triggering (5 reasons are possible)

Initial Compressed Mode Configuration

RRC: Physical Channel Reconfiguration Complete NBAP: Compressed Mode Command RRC: Measurement Control

GSM RSSI Measurement

RRC: Measurement Report RRC: Cell Change Order from UTRAN

RANAP: SRNS Context Request

RANAP: SRNS Context Response RANAP: SRNS Data Forward Command RANAP: IU Release Command RANAP: IU Release Complete

• •

154

In most cases BSIC verification is not required (data interrupt as UE moves to 2G) PS makes use of RRC: CELL CHANGE ORDER FROM UTRAN message © 2006 Nokia

3G -> 2G Handover measurement triggering

IS Handover Triggering Reasons 2. Quality deterioration report from UL outer loop PC FMCI: IFHOcauseUplinkQuality FMCG: GSMcauseUplinkQuality

1. DL DPCH approaches its maximum allowed power FMCI: IFHOcauseTxPwrDL FMCG: GSMcauseTxPwrDL

3. Low measured absolute CPICH Ec/No, event 1E/1F FMCI: IFHOcauseCPICHEcNo FMCG: GSMcauseCPICHEcNo

5 . Low measured absolute CPICH RSCP, events 1E/1F FMCI: IFHOcauseCPICHrscp, FMCG: GSMcauseCPICHrscp

HO trigger

4. UE Tx power approaches its maximum allowed power, event 6A/6D FMCI: IFHOcauseTxPwrUL FMCG: GSMcauseTxPwrUL

6 . Others (Not implemented in RAN 1.5): e.g. Traffic & load reason IS-HO, etc

Frequency Measuring Control for Inter-Frequency = FMCI Frequency Measuring Control for Inter-System (GSM) = FMCG

e.g. P-CPICH Ec/No

Measurement triggering: CPICH Ec/No Reporting event: 1E: A P-CPICH exceeds an absolute threshold (triggered if one) 1F: A P-CPICH falls below an absolute threshold (triggered if all) Cell 1

Cell 2

Cell 3 1E: HHoEcNoCancel

absolute threshold

1F: HHoEcNoThreshold

1E: HHoEcNoCancelTime

time

1F: HHoEcNoTimeHysteresis

Measurement triggering: CPICH Ec/No • RNC starts IF/IS measurement when event 1F occurs for all cells in the active set: A Primary CPICH becomes less than an absolute threshold • RNC stops IF/IS measurement when event 1E occurs for at least one cell of the active set : A Primary CPICH becomes better than an absolute threshold • Note:IF/IS measurements can be stopped if event 1Fs are cancelled by events 1E only when IFHO/ISHO was not successful and only inside the time between CM measurements, specified by the time InterFreqMinMeasInterval ,GsmMinMeasInterval/default 10s, recommendation 2s . • Filtering applied before event evaluation in the UE: – FMCS: EcNoFilterCoefficient/0= 200ms filtering period

Measurement triggering: CPICH Ec/No •

•

Event 1E parameters: – Triggering conditions: Active set cells – Hysteresis: not used in 1F – Threshold used frequency: FMCS : HHoEcNoCancel/ -9dB – Time-to-trigger: FMCS: HHoEcNoCancelTime/ 1280 ms – Amount of reporting: infinity – Reporting interval: not applied. – Reporting cell status: max 3 active cells. Event 1F parameters: – Triggering conditions: Active set cells – hysteresis: not used in 1F – Threshold used frequency: FMCS : HHoEcNoThreshold / - 12dB (range 0..-24 dB) – Time-to-trigger: FMCS: HHoEcNoTimeHysteresis / 100 ms (range 0..5000ms) – Amount of reporting: infinity – Reporting interval: not applied. – Reporting cell status: max 3 active cells.

Measurement triggering: CPICH RSCP

e.g. P-CPICH Rscp

Reporting event: 1E: A P-CPICH exceeds an absolute threshold (triggered if one) 1F: A P-CPICH falls below an absolute threshold (triggered if all)

Cell 1

Cell 2

Cell 3 1E: HHoRscpCancel

absolute threshold

1F: HHoRscpThreshold

1E: HHoRscpCancelTime

time 1F: HHoRscpTimeHysteresis

Measurement triggering: CPICH RSCP • UE continually monitors pilot channels of BTSs in AS • If RSCP of a Node B falls below threshold, HHoRscpThreshold, UE sends event 1F report • RNC starts IF/IS measurements when event 1F occurs for all cells in AS • RNC stops IF/IS measurements when event 1E occurs for at least one cell of AS • Note:IF/IS measurements can be stopped if event 1Fs are cancelled by events 1E only when IFHO/ISHO was not successful and only inside the time between CM measurements, specified by the time InterFreqMinMeasInterval GsmMinMeasInterval/default 10s, recommendation 2s . • UE filtering applied before event evaluation using HHoRscpFilterCoefficient (FMCS) /200ms, range 200…1600ms

Measurement triggering: CPICH RSCP •

Event 1E (A primary CPICH exceeds an absolute threshold) parameters: – Triggering conditions: Active set cells – hysteresis: not used in 1E – Threshold used frequency: (FMCS) : HHoRscpCancel/ - 90 dBm – Time-to-trigger: (FMCS): HHoRscpCancelTime/ 1280 ms – Amount of reporting: infinity – Reporting interval: not applied. – Reporting cell status: max 3 active cells.

•

Event 1F (A primary CPICH falls below an absolute threshold) parameters: – Triggering conditions: Active set cells – Hysteresis: not used in 1F – Threshold used frequency: HHoRscpThreshold (FMCS)/ - 93 dBm – Time-to-trigger: HHoRscpTimeHysteresis (FMCS)/ 100 ms – Amount of reporting: infinity – Reporting interval: not applied. – Reporting cell status: max 3 active cells.

3G -> 2G Measurements

ISHO parameters CPICH RSCP (Event 1F) •Thresholds: HHoRscpThreshold HHoRscpCancel L3 filter: HHoRscpFilterCoefficient •Timers: HHoRscpTimeHysteresis HHoRscpCancelTime

UE Tx Power (Event 6A) •Threshold: GsmUETxPwrThrXX •L3 filter: GsmUETxPwrFilterCoeff •Hysteresis margin: GsmUETxPwrTimeHyst •Data rate threshold

CPICH Ec/Io (Event 1F) •Thresholds: HHoEcNoThreshold HHoEcNoCancel •L3 filter: Done already for SHO •Timers: HHoEcNoTimeHysteresis HHoEcNoCancelTime

DL DPCH power •Threshold: GsmDLTxPwrThrXX •Data rate threshold HHOMAxAllowedBitrateD L

UL Quality •Timer: ULQualDetRepThreshold •Data rate threshold

GSM measurement reporting GsmMeasRepInterval GsmNcellSearchPeriod GsmMinMeasInterval GsmMaxMeasPeriod

HHOMAxAllowedBitrateU L

Handover Triggering

HHOMAxAllowedBitrateUL (XX=AMR,CS,NrtPS,RtPS)

Decision Algorithm AdjgTxPwrMaxTCH AdjgRxLevMinHO (n) GsmMeasAveWindow

Handover Execution 2G-to-3G

back prevention

GsmMinHoInterval

ISHO measurements •

After HO triggering message is sent to RNC, a RRC message ”Measurement Control” is sent to UE containing details of the measurement that the UE must execute. Measurement reporting is periodical. Max 6 GSM cells could be measured by UE and reported to RNC. No filtering in measurements by UE RRC: ”Measurement control ” message (GSM RSSI measurements)

RNC

UE

•

Upon reception of the measurements reported by the UE, RNC applies a sliding averaging window to the RXLEV measurements. The averaged levels are used as input to the IS-HO decision algorithm. UE

GsmMeasRepInterval (default 0.5s)

RNC

RRC: ”Measurement report” RRC: ”Measurement report”

The first measurement report has info from the best GSM cell: BCCH freq & RSSI, no filtering used in UE

RXLEV measurements are reported through ”Measurement report” messages

Measurement Control Parameters: FMCG •

•

• •

GSMMeasRepInterval: 0.5 seconds – This is the interval between measurement reports, which are sent to BTS – This parameter should be kept to 0.5 seconds. Increasing the reporting interval would increase the IS-HO process delay. GSMMinMeasInterval: 2 s – This is Minimum Measurement Interval, wait time when the following CM starts. In case of an unsuccessful IS-HO attempt, the network will deactivate compressed mode for a time period given by this parameter, thus better value will be 2 s to speed up the reactivation of CM. GSMMeasAveWindow: 6 reports – This is Measurement Averaging Window size, sliding window is used GSMMaxMeasPeriod: 12 reports – This is Maximum Measurement Period which determines the maximum allowed duration of the inter-system measurement – If the RNC is not able to execute an inter-system handover, it shall stop the inter-system measurements after the UE has sent the predefined number of measurement reports to the RNC.

Measurement Control Parameters: FMCG • •

•

Maximum allowed duration of the inter-system measurement is calculated: – GSMMeasRepInterval * GSMMaxMeasPeriod (=0.5*12) =6s, This seems to be too long time, because based on field measurements BSIC and RSSI delays are about 3 seconds, so it makes senses to reduce the value of this parameter to some value about 3 seconds, otherwise, if the BSIC or RSSI measurements fail or if the IS-HO execution is not possible to due low GSM RSSI levels, the network will not deactivate compressed mode until the timer of 10 seconds has expired. Thus, decreasing the parameter value will allow the UE/network to initiate a new IS-HO attempt. Proposed value for GSMMaxMeasPeriod is 6 GSMNcellSearchPeriod: 0 – This is neighbour cell search period parameter, ISHO is not allowed until the are enough measurement reports given by this parameter – O means that only 1 measurement result is enough for decision making – Duration of the cell search period is calculated: – GSMRepInterval * GSMNcellSearchPeriod).

ISHO: BSIC Verification • •

•

After the selection of the target GSM cell, the RNC sends to UE the RRC message "Measurement control” which includes details to measure ”BSIC” . UE stops RSSI measurements and updates the transmission gap pattern to the pattern used for BSIC decoding. The measurement reports are sent periodically to RNC. If the UE is unable to decode the BSIC during the given period, the BSIC measurement operation is aborted. IS-HO trigger

WCDM A RRC: ”Measurement control ” message (BSIC decoding)

RNC

Target Cell found

RSSI meas. TRSSI depends on •Numbers of GSM cells in

the neighbour cell list •Reporting interval •Sliding averaging window •Transmission gap pattern for RSSI measurements

IS-HO command

BSIC verification TBSIC depends on : •Transmission gap pattern for

BSIC decoding

3G -> 2G Handover decision

Inter-RAT HO Decision On this page, you find conditions, which have to be satisfied, before an inter-frequency handover can be conducted. The best neighbouring cell must fulfil following criterion („best“ according to Ec/No):

AVE_RXLEV_NCell(n) > GSMncellRxLevMinHO(n) + max(0, GSMncellTxPwrMaxTCH(n) P_max) where • AVE_RXLEV _Ncell(n) is the averaged GSM carrier RSSI value of the GSM neighbour cell(n), averaging done directly from dBm values (no linear averaging); GSMMeasAveWindow / 6, 1…32 meas report. • GSMncellRxLevMinHO(n) determines the minimum Required RSSI (dBm) level of the neighbour cell(n). ( -95 dBm) • GSMncellTxPwrMaxTCH(n) indicated the maximum Tx power level (dBm) an UE may use in GSM neighbour cell(n). • P_MAX is the maximum UE power capability. • If several GSM cells fulfils the equation above, cells are ranked based on HOPG: GSMncellPriorityCoverage/0, range 0…7 • A cell is ranked higher than another cell if it has a higher priority level even though its signal strength condition was worse • Inter-system HO could be forbidden during the first measurements reports from the UE, to let the UE report all the candidate inter-system cells in its neighbourhood. • FMCG FMCGNcellSearchPeriod / 0

ISHO Decision AVE_RXLEV_NCell(n) > AdjgRxLevMinHO(n) + max(0, AdjgTxPwrMaxTCH(n) - P_max) GSM cell

AdjgRxLevMinHO(n)



max(0, AdjgTxPwrMaxTCH(n) - P_max)

3G -> 2G Handover signalling

ISHO analysis with Nemo ISHO IS TRIGGERED EVENT 1F

-(48-32)/2 = -8 dB  -8.5  EcNo < -8 -115 + 11 = -104 dBm  -105  Rscp < -104

Compressed mode started Tstart = 17:22:41.7 Tstop = 17:22:53.7

Compressed mode stopped

MW = 12 s

•GsmMaxMeasPeriod x GsmMeasRepInterval +4 x GsmMeasRepInterval = 20 x 0.5+ 4x0.5=12 s

RxLev = -110 + 4 = -106 dBm

AdjgRxLevMinHO = -95 dBm

4 POOR GSM COVERAGE No suitable cell

AMR Handover procedure overview (1) RRC connection setup

ISUP signalling

Parameters for HO event trigger e1e, e1f, e6a,e6b

AMR Handover procedure overview (2)

ISUP signalling

Mobility management; several AS cell add & cell drops

AMR Handover procedure overview (3)

Mobility management; several AS cell add & cell drops

Measurement report to Compressed trigger CM Mode Parameters

AMR Handover procedure overview (4) RNC sends updated GSM NB UE list sends inter RAT meas. RNC commands UE to verify Results BSIC of best reported cellverified Target cell BSIC RNC triggers HO to GSM target cell Timing advance information UE ends HHO - procedure UE is handed over to GSM

2G signalling

Physical Channel reconfiguration RRC: Physical Channel reconfiguration

Measurement Control new RAT NB list


[..] new inter RAT NB list

Measurement info

UE Measurement Report GSM cells-RSSI measurements


measured best cell by ARFCN measured 2nd best cell by ARFCN measured 3rd best cell by ARFCN measured 4th best cell by ARFCN measured 5th best cell by ARFCN measured 6th best cell by ARFCN

Measurement Control carrying target cell info


UE shall stop measuring RSSI of RAT N and focus on best cell´s BSIC verificatio

UE Measurement Report target GSM cell-BSIC verification


UE reports verified BSIC of best cell to

Handover from UTRAN command

RRC: HO from UTRAN command

Handover command GSM signalling

L3: Handover command

2G cell information (RF&configuration)

2G cell information (PC)

2G cell information (Security)

Cell Selection and Reselection

2G <-> 3G inter working Idle mode

2G -> 3G reselection 3G -> 2G reselection

Connected mode

2G -> 3G handover CS AMR 2G -> 3G handover PS 3G -> 2G handover CS AMR 3G -> 2G handover PS

3G -> 2G reselection

Cell Reselection Cell Selection S-Ccriteria • The cell selection criteria S Squal = Q – Qqualmin are defined as follows: TS 25.304 5.2.3.1.2

qualmeas

• The cell selection criterion S for a suitable cell is fulfilled when: • Where:

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Squal > 0 Srxlev > 0

Squal

Cell Selection quality value, (dB). Not applicable for TDD cells or GSM cells Srxlev Cell Selection RX level value (dB) Qqualmeas Measured cell quality value. The quality of the received signal expressed in CPICH Ec/N0 (dB) for FDD cells. Not applicable for TDD cells or GSM cells. Qrxlevmeas Measured cell RX level value. This is received signal, -115dBm CPICH RSCP for FDD cells (dBm), P-CCPCH RSCP -101dBm for TDD cells (dBm) and RXLEV for GSM cells (dBm). Qqualmin Minimum required quality level in the cell (dB). -18dB Not applicable for TDD cells or GSM cells. Qrxlevmin Minimum required RX level in the cell. (dBm) -115dBm Pcompensation max(UE_TXPWR_MAX_RACH – P_MAX, 0) (dB) UE_TXPWR_ Maximum TX power level an UE may use when MAX_RACH accessing the cell on RACH (read in system information), (dBm) P_MAX Maximum RF output power of the UE, (dBm)

intra GSM

Cell Reselection Cell Selection S-Ccriteria • If system info in the cell indicates that HCS is not used (UseOfHCS) then for intrafreq, inter-freq and inter-system the UE shall: •

If Squal > Sintrasearch, UE need not perform intra-frequency measurements. If Squal <= Sintrasearch, perform intra-frequency measurements.

•

If Squal > Sintersearch, UE need not perform inter-frequency measurements If Squal <= Sintersearch, perform inter-frequency measurements.

•

If Squal > SsearchRAT m, UE need not perform measurements on cells of RAT "m". If Squal <= SsearchRAT m, perform measurements on cells of RAT "m".

Cell Reselection Cell Selection S-Ccriteria Region

Condition

1

Squal > Sintrasearch

Neighbour cells to be measured ONLY TRIGGER FOR MEASURE None

2

Sintersearch < Squal  Sintrasearch

Intra-frequency cells

3

SsearchRATm < Squal  Sintersearch Squal  SsearchRATm

Intra- and inter-frequency cells

4

Sintrasearch =

Intra-, inter-frequency and inter-RAT cells

4 dB: Equate to –16dB Ec/No

S S intrasearch intersearch

Sintersearch = 2 dB: Equate to –18dB Ec/No SsearchRAT m, = 0dB: Equate to –20dB Ec/No 4

3

2

1 WCDMA CELL

Ssearch RAT

Cell Reselection Cell Selection S-Ccriteria •

The following cell re-selection criteria is used for intra-freq, inter-freq & inter-RAT:

Rs = Qmeas,s + Qhysts(COMAPRED WITH SELF) Where:

Rn = Qmeas,n – Qoffsetn(COMPARED WITH

ADJACENT CELLS)

Qmeas

Quality value. The quality value of the received signal expressed in CPICH_Ec/No or CPICH_RSCP_LEV for FDD cells as set by the Cell_selection_and_reselection_quality_measure information element, PCCPCH_RSCP_LEV for TDD cells and RXLEV for GSM cells.

Qhyst1

This specifies the hysteresis for serving cell that is of different radio access modes or technologies AND for serving FDD cell when cell_selection_and reselection-quality_measure is set CPICH RSCP..

Qhyst2

This specifies the hysteresis for serving FDD cell when the cell_selection_and reselection-quality_measure is set CPICH Ec/No.

Qoffset1

This specifies the offset between the two cells when the neighbour cells that are of different radio access modes or technologies AND for neighbour FDD cells when cell_selection_and reselection-quality_measure is set CPICH RSCP This specifies the offset between the two cells when neighbour FDD cells when the cell_selection_and reselection-quality_measure is set CPICH Ec/No.

Qoffset2

Concept

Cell Reselection 3G -> 2G CPICH EcNo

UE starts GSM measurements if CPICH Ec/No < qQualMin + sSearchRAT

SintraSearch

First ranking of all the cells based on CPICH RSCP (WCDMA) and RSSI (GSM)

SinterSearch

Rs = CPICH RSCP + Qhyst1 Rn= Rxlev(n) - Qoffset1

SsearchRAT

Neighbour WCDMA or GSM cell calculation with offset parameter

qQualMin No

Rn (GSM) > Rs (WCDMA) And Rxlev (GSM) >QrxlevMin

Serving WCDMA cell calculation, with hysteresis parameter

Yes

Second ranking only for WCDMA cells based on CPICH Ec/No Rs = CPICH Ec/No + Qhyst2 Rn=CPICH_Ec/No(n)-Qoffset2

Cell re-selection to GSM Cell re-selection to WCDMA cell of highest R value

Cell Reselection 3G -> 2G HCS in use:

HCS not in use:

Serving + measured neighboring cells

Serving + measured neighboring cells

S-Criteria OK

S-Criteria OK

Fast MS Cells with Lower HCS Priority than in Serving cell

Cells with Highest HCS Priorities & H>0

Best R

Best R

If No Cell with H>0 accept all neighbors

Best R

Cell Reselection Neighbour measurements summary SsearchRAT m

SlimitsearchRAT m

Intra-frequency Inter-freqency Inter-RAT

Intra-frequency Inter-frequency

Intra-frequency Inter-freqency Inter-RAT

Intrafrequency Interfrequency Higher HCS priority inter RAT

Sintersearch Sintrasearch

Intrafrequency

Intra-frequency Inter-frequency

Sx=Squal= Ec/No

No need to measure neighbour cells

Higher HCS priority Intra-frequency Inter-frequency

HCS not used

HCS used

Cell Reselection 3G -> 2G

•

•

•

Performance

There is no timer defined how long the GSM should be fulfilling the re-selection criteria However there is running average of 4 GSM measurements which provides some protection against ping – pong (time vice –based on DRX cycle length and as sliding window average) In case additional protection is needed it can be arranged by using the Qhyst1 parameter (for WCDMA serving cell RSCP) or AdjgQoffset1 (for GSM neighbouring cell RxLev) First ranking of all the cells based on CPICH RSCP (WCDMA) and RSSI (GSM) Rs = CPICH RSCP + Qhyst1 Rn= Rxlev(n) - Qoffset1

Cell Reselection 3G -> 2G

Parameter Tuning General

• When to trigger the cell reselection to 2G depends greatly on: – how much the 3G network is requested to be utilised • target is to maximise the utilisation of WCDMA network but… – what is the desired CSSR • …at the same time maximise the quality – minimise the possibility of ping – pong • Due to very different fading conditions, there should be couple of different parameter sets for 3G -> 2G reselection – Outdoor, typical outdoor to dedicated indoor (in case of missing 3G indoor) – 3G border – Special indoor cases without dedicated 3G where the UE speed is high (e.g. tunnels)

ISHO Cell Reselection 3G -> 2G

Parameter Tuning Outdoor

Call Setup status statistics for each Ec/No range

WCDMA intra frequency search should be started latest at ~ qQualMin +

100% 90% 80% 70%

sSearchIntra = -8 … -10dB

[%]

60% 50% 40% 30% 20% 10% 0% > -4

-4 to -

-6 to -

-8 to -

6

8

10

-10 to

-12 to

-12 -14 Ec/No [dB]

-14 to

-16 to

-18 to

-16

-18

-21

As long as the Ec/No is >12…-14dB the CSSR is excellent qQualMin + sSearchRAT ~ -14dB

<-21

2G -> 3G reselection

Cell Reselection Algorithm from GSM to FDD-WCDMA (cs)

GSM MS starts WCDMA measurements if : RLA_C< F(Qsearch_I) for 0 F(Qsearch_I) for 7
at least every 5 s

check Measurement Updates: • RLA_C value of the serving cell • + least 6 strongest non serving GSM cells

no priorities between WCDMA neighbours

If, for suitable UMTS cell & for a period of 5 s: CPICH RSCP > RLA_C + FDD_Qoffset

Fdd_Qoffset: select allways (value is -infinity) WCDMA cell reselection

and CPICH Ec/No  FDD_Qmin

FDD_Qmin= -13 dB

Cell Reselection Algorithm from GSM to FDD-WCDMA (cs) • In GSM the UE is usually set to measure the 3G neighbours all the time I.e. Qsearch_I and Qsearch_P are both set to 7

UE starts WCDMA measurements if Rxlev running average (RLA_C) is below or above certain threshold: RLA_C  Qsearch_I and Qsearch_P (GPRS)

Cell Reselection Parameters • Qsearch_I and Qsearch_P define thresholds. The threshold value also indicates, when the measurements have to be initiated and performed. The measurements are either started, when the serving cell„s RLA is below or above the threshold value. The default value is 15. • FDD_Qoffset and FDD_GPRS_Offset define offset values, which have to be added to the RLA of the serving and non-serving GSM cells. The result is compared with the RSCP value of the WCDMA cell. The default parameter is 0. • FDD_Qmin defines a minimum CPICH Ec/No threshold for WCDMA cell for cell reselection. • FDD_REP_QUANT defines the reporting quantity for UTRAN cell (1=Ec/No or 0=RSCP, default: 1). • 3G_Search_PRIO is used to inidicate to the MS if 3G cells can be looked for when BSIC decoding is required. (0=no, 1=yes, default: 1) The 3G Cell Reselection list is only used by multi-RAT MSs. The system information SI2quater and SI2ter can be used to provide 3G cell information. If the two system information messages carry 3G cell information, than their lists have to be combined in the UE„s 3G Cell Reselection list, which may then hold up to 96 UMTS cells. Up to 8 carrier frequency bands can be stored in this list, too.

Cell Reselection Algorithm Algorithm for cell re-selection from GSM (GPRS) to the FDD mode in UTRAN Pre-requisite for cell re-selection to UMTS is, that UTRAN carrier bands are included in the (GPRS) 3G Cell Reselection list. If so, the MS must update • RLA_C (RLA_P) value for the serving cell and • at least 6 strongest non serving GSM cells at least every 5 seconds. Thereafter, the MS can re-select a suitable UTRAN cell, based on the S-Criterion. If an FDD cell is suitable, following two conditions must have been met: • For a period of 5 seconds, the measured RSCP value must exceed the PLA_C (RLA_P) of the serving GSM and of all non-serving GSM cells by the value FDD_Qoffset (FDD_GPRS_Qoffset). Did a cell re-selection occur within the previous 15 seconds, the FDD_Qoffset value is increased by 5 dB. • The measured Ec/No value of the FDD cell must be greater or equal than the broadcasted value FDD_Qmin. • If the UE as performed a cell re-selection to UTRAN within the previous 5 seconds, a cell re-selection back to UTRAN is not allowed, when a suitable cell can be found within GSM.

Cell Re-selection Parameters •

Range of FDD_Qmin – Recommended value is 7 (-13 dBm)

New mapping from 05.08 [late 2003]: UEs have to support new parameter range !

Range 0

1

2

3

4

5

6

7

dBm -20 -19 -18 -17 -16 -15 -14 -13

Fdd_Qmin mapping Aif parameter 0 1 2 3 4 5 6 7 Fdd_Qmin (old) [dB] -20 -19 -18 -17 -16 -15 -14 -13 Fdd_Qmin (new) [dB] -20 -6 -18 -8 -16 -10 -14 -12

•

FDD_REP_QUANT defines the reporting quantity for UTRAN cell (1=Ec/No or 0=RSCP, default 1)

•

3G_Search_PRIO parameter allows to extend the BSIC reporting interval from 10 s to 13s by checking the BSICs from non-serving BCCH carriers and also make WCDMA measurements as often as possible. Range is 0=no, 1=yes, default value 1  Defined in the SI2quater and PSI3quater if PBCCH is allocated.

old

Parameter

Qsearch_I Qsearch_PQsearch_P FDD_QMin

Name for 2quater Sys Info (SI)

2quater

3quater

2ter

FDD_(GPRS) FDD_REP_ 3G_search_ Qoffset QUANT PRIO 2quater

2ter

2(3)quarter (PBCCH)

Cell Re-selection Parameters • In case the reselection is wanted to happen immediately when the 3G is “good enough” just based on CPICH Ec/No value (RSCP threshold is not used i.e. reselection is done RSCP > Rxlev – infinity) FDD_Qoffset

UE can select WCDMA cell if the level of the serving GSM and non-serving GSM cells has been exceeded by certain offset for a period of 5 s: CPICH RSCP > RLA_C + FDD_Cell_Reselect_Offset

Mapped to:

Comment:

-

Always select irrespective of RSCP value

1

-28dB

Reselect in case WCDAM RSCP > GSM RXLev (RLA_C) –28dB

2 … 14 15

-24dB … 24dB 28dB

(FDD_Cell_Reselect_Offse t) 0

Reselect in case WCDAM RSCP > GSM RXLev (RLA_C) +28dB

How to avoid ping-pong ? •

As a general rule the value for FDD_Qmin parameter can be set to – 11…-12 dB (i.e. for the case where the QqualMin +Ssearch_RAT = 14dB) CPICH Ec/No

FDD_Qmin >= QqualMin + Ssearch_RAT

FDD_Qmin >=-12

QqualMin + Ssearch_RAT = -14dB

UE will re-select WCDMA cell in case it's quality is acceptable:

CPICH Ec/No  Minimum_FDD_Threshold

• The “rule” to set the FDD_Qmin value has not been possible to be fulfilled until the specification change (05.08 v8.18.0, 2003-8) has been implemented to the UEs – as below

QqualMin = -18dB

t Camping in 3G

Camping in 2G

Camping in 3G

Fdd_Qmin mapping Aif parameter 0 1 2 3 4 5 6 7 Fdd_Qmin (old) [dB] -20 -19 -18 -17 -16 -15 -14 -13 Fdd_Qmin (new) [dB] -20 -6 -18 -8 -16 -10 -14 -12

GSM BCCH 2Quater / 2Ter

Cell Re-selection Example Non GPRS case RSCP/ RLA_C

Ec/No Cell re-selection to WCDMA

RLA_C

Serving GSM Cell

Qsearch_I=0 (-98 dBm) FDD_Qoffset =6 (-8 dB)

Measurements starts (serving cell)

FDD_Qmin=0 (-20 dB)

RSCP Neighbour WCDMA Cell Ec/N0

Minimum Quality Requirement for WCDMA t 5 sec.

Cell Re-selection Example GPRS case RSCP/ RLA_C

Ec/No RLA_P Cell re-selection to WCDMA

FDD_GPRS_Qoffset =10 (8 dB) Qsearch_P=0 (-98 dBm)

Serving GSM Cell (Best)

RSCP

Measurements starts (serving cell)

FDD_Qmin =-20 dB Neighbour WCDMA Cell

Ec/N0

Minimum Quality Requirement for WCDMA t 5 sec.

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