1. Channel Switching Capability Impacting features Channel Switching
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
Channel Switching
Capability
Optimizes the utilization of radio resources, by switching UE’s to the most suitable transport channel based on traffic volume (throughput), radio resources availability, radio conditions and mobility.
Only applies to PS data (Interactive/background).
Impacting features
Admission Control
Congestion Control
Soft Handover
RAN Feature Presentation
Rev A 14

2. Channel type switching
EUS/WR/AE
Jul 22, 2005
Channel Switching
Channel type switching
User 1
DATA
Switch to
dedicated
Common Channel (Cell_FACH)
Switch to
common
TTime-out
Packet
Packet
Packet
Dedicated Channel (Cell_DCH)
Release dedicated
channel
In order to make packet transmissions efficient, WCDMA supports two different types of packet transmission schemes.
(Click)
Small and infrequent packets are transmitted on on the common random access channel as the data is attached to the random access bursts. The benefit of that is that these packets will experience very short delays.
For large or frequent packets, a dedicated channel is used. The benefit of this approach is that the fast quality based power control is up and running, which results in a high spectrum efficiency. Another benefit is that packets on dedicated channels can be scheduled by the scheduling algorithm. Note that also the control information (pilot bits, power control bits and TFI) is transmitted on the dedicated channel even when no packets are transmitted. This means that the channel is prepared for new arriving packets. Finally the dedicated channel is released when it has been unused during a certain amount of time.
RAN Feature Presentation

3. Channel rate switching
EUS/WR/AE
Jul 22, 2005
Channel Switching
Channel rate switching
Up-switch e.g Kbps
Down-switch e.g Kbps
Bit rate
Distance
from RBS or
Load in
the cell
Distance
from RBS or
Load in
the cell
RAN Feature Presentation

4. Overview of trigger mechanisms
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
Overview of trigger mechanisms
Channel Switching Algorithms
Down/up switch based on coverage and user activity
Congestion Control
Channel Switching
Admission Control
Down-switch from dedicated to common channel to resolve congestion
Down-switch from one dedicated channel to another, e.g. from 64/384 to 64/128 to free up radio resources
Soft Handover
Down-switch from 64/384 or 64/128 to 64/64 if Admission Control denies adding a radio link to the Active Set
RAN Feature Presentation
Rev A 14

5. Single RAB State Transitions
Ericsson Proprietary
EUS/WR/AE
Jul 22, 2005
9/15/2003
Channel Switching
Single RAB State Transitions
Connected Mode
1. Common to Dedicated 1
Dedicated Channel (Cell_DCH)
Cell_DCH 64/384 kbps UL/DL
3. Dedicated to common 3
2. Dedicated to dedicated
Single RAB 2b 2a
Cell_DCH 64/128 kbps UL/DL
Cell_DCH 64/64 kbps UL/DL
Common Channel (Cell_FACH)
4. Common to Idle Mode 4
RACH/FACH (max. 32 kbps)
Idle Mode
Rev A
RAN Feature Presentation 14

6. 1. Common to Dedicated Evaluation cont’
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
1. Common to Dedicated Evaluation cont’
Monitors if the UE shall be switched from a common to a dedicated transport channel due to large amount of user data buffered in the RNC or the UE.
UL RLC buffer load
Idle Mode
RACH/FACH
Common Channel (Cell_FACH)
Cell_DCH 64/64 kbps UL/DL
Cell_DCH 64/128 kbps UL/DL
Cell_DCH 64/384 kbps UL/DL
Dedicated Channel (Cell_DCH)
Connected Mode
Up-switch X
ulRlcBufUpswitch [256 bytes]
A request is sent to Admission Control to perform an up-switch from Cell_FACH to Cell_DCH 64/64 kbps or
DL RLC buffer load
Up-switch X
dlRlcBufUpswitch [512 bytes]
Rev A
RAN Feature Presentation 14

7. Ericsson Proprietary
EUS/WR/AE
Jul 22, 2005
9/15/2003
Channel Switching
2a. Dedicated to Dedicated Coverage triggered Down-Switch Evaluation cont’
Monitors if a switch to a lower rate radio bearer is required due to coverage.
DL TX code power > [Power Alarm Threshold], defined as Max Code Power – downswitchPwrMargin. A down-switch to Cell_DCH with lower bitrate is requested. Timer coverageTimer starts.
Idle Mode
RACH/FACH
Common Channel (Cell_FACH)
Cell_DCH 64/64 kbps UL/DL
Cell_DCH 64/128 kbps UL/DL
Cell_DCH 64/384 kbps UL/DL
Dedicated Channel (Cell_DCH)
Connected Mode
Pcode
DL TX code power > [Power Alarm Threshold] – reportHysteresis and timer coverageTimer expires. The down-switch is executed.
DL TX code power < [Power Alarm Threshold] – reportHysteresis while the timer is running, the down-switch request is cancelled.
Rev A
RAN Feature Presentation 14

8. 2b. Dedicated to Dedicated Up-Switch Evaluation
EUS/WR/AE
Ericsson Proprietary
Jul 22, 2005
9/15/2003
Channel Switching
2b. Dedicated to Dedicated Up-Switch Evaluation
Monitors if the throughput becomes close to the max user bandwidth and switch to the next higher bitrate radio bearer is required.
DL throughput is > 90 % of max. possible bitrate on current radio bearer AND the DL code power is < [Power up-switch threshold] – reportHysteresis, where the [Power up-switch threshold] is defined as Max Code Power – downswitchPwrMargin – Estimated Power Increase – upswitchPwrMargin. Timer upswitchTimer starts.
Pcode
Idle Mode
RACH/FACH
Common Channel (Cell_FACH)
Cell_DCH 64/64 kbps UL/DL
Cell_DCH 64/128 kbps UL/DL
Cell_DCH 64/384 kbps UL/DL
Dedicated Channel (Cell_DCH)
Connected Mode
DL throughput is < 90 % of max. possible bitrate on current radio bearer OR the DL code power becomes >= [Power up-switch threshold] while the upswitchTimer is still running. The timer stops and no up-switch is executed.
[2.9 dB for up-switch from 64-to-128 kbps]
[4.7 dB for up-switch from 128-to-384 kbps]
DL throughput is > 90 % of max. possible bitrate of current RB AND the DL code power is < [Power up-switch threshold] when timer upswitchTimer expires. The up-switch request is sent Admission Control.
RAN Feature Presentation
Rev A 14

9. 3. Dedicated to Common Evaluation
EUS/WR/AE
Ericsson Proprietary
Jul 22, 2005
9/15/2003
Channel Switching
3. Dedicated to Common Evaluation
Monitors if a switch from a Cell_DCH to Cell_FACH is required due to a decrease in transmitted user data.
UL and DL throughput increases above threshold downswitchTimerThreshold before the timer expires. The timer stops and no down-switch occurs.
Idle Mode
RACH/FACH
Common Channel (Cell_FACH)
Cell_DCH 64/64 kbps UL/DL
Cell_DCH 64/128 kbps UL/DL
Cell_DCH 64/384 kbps UL/DL
Dedicated Channel (Cell_DCH)
Connected Mode
DownswitchTimer
DownswitchTimer
UL and DL throughput falls below threshold defined by parameter downswitchThreshold and timer downswitchTimer starts.
The timer expires and a request is issued to down-switch from common to dedicated channel.
RAN Feature Presentation
Rev A 14

10. 4. Common to Idle Evaluation
Ericsson Proprietary
EUS/WR/AE
9/15/2003
Jul 22, 2005
Channel Switching
4. Common to Idle Evaluation
Monitors if a switch from Cell_FACH to Idle mode is required due to a complete lack of user data transmission.
Idle Mode
RACH/FACH
Common Channel (Cell_FACH)
Cell_DCH 64/64 kbps UL/DL
Cell_DCH 64/128 kbps UL/DL
Cell_DCH 64/384 kbps UL/DL
Dedicated Channel (Cell_DCH)
Connected Mode
If both the UL and DL throughput is zero for a duration specified by parameter inactivityTimer, a request is sent to the Connection Handling function and further to Core via Iu, to release the connection.
Rev A
RAN Feature Presentation 14

11. Multi-RAB Down-switch Evaluation
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
Multi-RAB Down-switch Evaluation
Monitors if a release (or downswitch) of PS I/B RAB shall be initiated due to lack of PS data throughput (zero), resulting in a single speech 12.2 kbps (or speech + PS 0/0) or CS64 RAB.
The SRNC measures the throughput in UL and DL every 500 ms. When the throughput is zero in both UL and DL, timer downswitchTimerUp (for CS64+PS8/8) or downswitchTimerSp (for speech+PS64/64) starts. If there is any throughput in UL or DL while the timer is running, the timer is stopped.
When the timer expires, a request is sent to release the PS I/B RAB (or to dowswitch if multiRabSp0Available) . The timer starts again in case there is any throughput in UL or DL before the PS RAB is released.
Rev A
RAN Feature Presentation 14

12. Multi-RAB Up-switch Evaluation
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
Multi-RAB Up-switch Evaluation
Monitors if an upswitch from multi-RAB SP0 to multi-RAB SP64 shall be initiated due to data buffered in either RNC or UE.
When the RLC buffer load in the uplink exceeds the threshold value set by the parameter ulRlcBufUpswitchMrab, a measurement report is sent from the UE. An upswitch request is issued upon reception of the measurement report. A request is also issued when the RLC buffer load in the RNC exceeds the threshold value set by the parameter dlRlcBufUpswitchMrab.
If the dlRlcBufUpswitchMrab parameter is set to 0, the MultiRAB Upswitch Evaluation algorithm is turned off, meaning that no upswitches from SP0 will occur, irrespective of the RLC buffer load.
Rev A
RAN Feature Presentation 14

13. Future releases Channel Switching speech + interactive
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
Future releases
activity/inactivity-based
switching UL and/or DL
DL throughput-
based upswitch
UL throughput-
coverage-triggered
downswitch (DL only)
choice based on UE-
and cell-capability
IDLE
FACH
DCH HS
384/HS
64/384
64/HS
64/128
64/64
128/128
stand-alone interactive RAB
speech
+ 0/0
+ 64/64
+ 64/HS
+ 384/HS
speech + interactive
RAB
PS RAB Establishment
Low/No RLC buffer load for
Inactivity timer period
Low/No throughput
Measurement for down
Switch timer period
RAN Feature Presentation
Rev A 14

14. Parameters related to Channel Switching
EUS/WR/AE
Ericsson Proprietary
9/15/2003
Jul 22, 2005
Channel Switching
Parameters related to Channel Switching
dlRlcBufUpswitch,ulRlcBufUpswitch: downlink/uplink threshold for channel switching from FACH/RACH to a dedicated channel (unit: bytes)
dlMaxPower: maximum power on the downlink for a specific RAB. The power is relative to the primary CPICH power. (unit: 0.1 dB).
downswitchPwrMargin: margin, in relation to maximum allowed code power, which indicates a high power usage (unit: 0.5 dB)
coverageTimer :Time during which the power is allowed to be high before a downswitch (DCH to DCH) is issued (unit: second)
reportHysteresis: Reporting hysteresis for the code power measurements in the node B (unit: 0.5 dB)
upswitchPwrMargin: upswitch (DCH to DCH) power margin (unit: 0.5 dB)
upswitchTimer: Time during which the bandwidth utilization is allowed to be high before an upswitch request is issued (unit: second)
downswitchThreshold: threshold for channel switching from dedicated channels to FACH/RACH (unit: kbps)
downswitchTimer: sets the time during which throughput has to be low in order to trigger a downswitch fro DCH to FACH (unit: decisecond)
downswitchTimerThreshold: timer threshold to achieve hysteresis for channel switching from dedicated channel to FACH/RACH (unit: kbps)
inactivityTimer: timer for sending of IU RELEASE REQUEST message to the CN for UE in common state (unit: minutes)
RAN Feature Presentation
Rev A 14