1. The three sets involved in 3G handover are the active set, monitored set, and detected set. The active set contains cells in soft handover, the monitored set contains cells to monitor, and the detected set contains detected cells. 2. The major difference between GSM and UMTS handover decision is that GSM uses time-based reporting while UMTS uses event-triggered reporting. 3. Events 1A-1F relate to changes in primary common pilot channel power levels and adding or removing cells from the active set.

1. 3G
1. What are the three sets in handover?
The 3 sets in handover are:
· Active set – the list of cells which are in soft
handover with UE.
· Monitored set – the list of cells not in active
set but RNC has told UE to monitor.
o Detected set – list of cells detected by the UE
but not configured in the neighbor list.
2. What are the major differences between
GSM and UMTS handover decision?
GSM:
Time-based: mobile measures of RxLev and
RxQual – mobile sends measurement report
every SACH period (480ms).BSC instructs
mobile to handover based on these reports.
UMTS:
· Event-triggered reporting – UE sends a
measurement report only on certain event
“triggers”.

2. 3G -Events
What are the events 1a, 1b, 1c, etc.?
· Event 1A – a Primary CPICH enters the reporting range, i.e. add a cell to active set.
· Event 1B – a primary CPICH leaves the reporting range, i.e. removed a cell from active set.
· Event1C – a non-active primary CPICH becomes better than an active primary CPICH, i.e.
replace a cell.
· Event 1D - change of best cell.
· Event 1E - a Primary CPICH becomes better than an absolute threshold.
· Event 1F – a Primary CPICH becomes worse than an absolute threshold.
8. What are event 2a-2d and 3a-3d?
Events 2A-2D are for inter-frequency handover measurements and events 3A-3D are for
IRAT
handover measurements.
· Event 3A: the UMTS cell quality has moved below a threshold and a GSM cell quality had
moved above a threshold.
· Event 3B: the GSM cell quality has moved below a threshold.
· Event 3C: the GSM cell quality has moved above a threshold.
· Event 3D: there was a change in the order of best GSM cell list.

3. 1.What are the typical values for 'reportingrange1a' and 'reportingrange1b'?
3 dB and 5 dB respectively.
2.What will be the impact when you change 'reportingrange1a' from 3 to 4 dB and
'timetotrigger1a' 100 to 320 ms, without changing any other parameters?
Reduction in number of Event1a
Delayed Event1a trigger
Reduction in Average Active Set Size
Delay in Event1a could increase DL interference, which could lead to a drop call or increase
in
Average Power Per User (reduction in cell capacity)
3.What is processing Gain?
Ans:- Processing gain is the ratio of chip rate over data bit rate,
usually represented in decibel (dB) scale. For example, with 3.84MHz chip rate and 12.2k
data
rate, the processinggain is:
PG12.2k = 10 * log (3,840,000 / 12,200) = 25dB

4. 1….Eb/No
Eb/N0 (the energy per bit to noise power spectral density ratio) is an important parameter
in
digital communication or data transmission. It is a normalized signal-to-noise ratio (SNR)
measure, also known as the "SNR per bit". It is especially useful when comparing the bit
error
rate (BER) performance of different digital modulation schemes without taking bandwidth
into
account.

5. 1….RSCP: The “Received Signal Code Power” (RSCP) is the collected RF energy after the
correlation / descrambling process, usually given in dBm. Only this code power is of interest
for
the following receiver stages when judging on the quality of the reception.
2…..Ec/Io: This is the ratio of the received energy per chip (= code bit) and the interference
level,
usually given in dB. In case no true interference is present, the interference level is equal to
the
noise level.
Because of the system gain (see 1), the interference level can be higher than the wanted
signal
level. Therefore, at the coverage border, the value of Ec/I0 is usually negative
3….RSSI: The Received Signal Strength Indicator (RSSI) is a value that takes into account both
RSCP and Ec/I0. It is usually given in dBm and can be calculated as follows: RSSI [dBm] =
RSCP [dBm] - Ec/I0 [dB]

6. 1…How many slots are there in a WCDMA Frame? How big is a frame in ms. how many
chips are there in a slot?
WCDMA Frame is 15 slots wide. It is 10ms in length. There are 2560 chips in one slot. Chip rate
is 3840 Kc/s
Length of frame = 10 ms
Number of chips in a frame = 3840 *10=38400 chips.
Number of chips in a slot = 38400/15= 2560 chips
2….What is Pilot Pollution?
Simply speaking, when the number of strong cells exceeds the active set size, there is “pilot
pollution” in the area. Typically the active set size is 3, so if there are more than 3 strong
cells
then there is pilot pollution.
Definition of “strong cell”: pilots within the handover window size from the strongest cell.
Typical
handover window size is between 4 to 6dB. For example, if there are more than 2 cells
(besides
the strongest cell) within 4dB of the strongest cell then there is pilot pollution.

7. CPICH-Common Pilot Indication Channel (CPICH) is broadcast from every cell
▪It carries no information and can be thought of as a “beacon”constantly transmitting the
Scrambling Code of the cell
▪It is this “beacon”that is used by the phone for its cell measurements for network
acquisition and handover purposes (Ec, Ec/Io).
1.If the UE can’t see the CPICH the UE can’t see the cell
2.Initial 3G network optimisation will be performed purely from CPICH measurements
Ec-The Received Signal Level of a particular CPICH (dBm)
▪Io-The Total Received Power (dBm)
▪Ec/Io-The CPICH Quality (The ratio of the above two values)

8. WCDMA Parameters
Channel B.W 5 MHz
Forward RF Channel Structure Direct Spread
Chip Rate 3.84 Mcps
Frame Length 10 ms (38400 chips)
No. of slots/frame 15
No. of chips/slot 2560chips (Max. 2560 bits)
Power Control Open and fast close loop (1.6
KHz)
Uplink SF 4 to 256
Downlink SF 4 to 512

9. Power Control
• Fast Closed Loop PC – Inner Loop PC
– Feedback information.
– Uplink PC is used for near-far problem. Downlink PC is to ensure that there is
enough power for mobiles at the cell edge.
• Two special cases for fast closed loop PC:
– Soft handover:- how to react to multiple power control commands from several
sources. At the mobile, a “power down” command has higher priority over
“power up” command.
– Compressed mode:- Large step size is used after a compressed frame to allow
the power level to converge more quickly to the correct value after the break.
• Open loop PC
– No feedback information.
– Make a rough estimate of the path loss by means of a downlink
beacon signal.
– Provide a coarse initial power setting of the mobile at the
beginning of a connection.
– Apply only prior to initiating the transmission on RACH or
CPCH.

10. WCDMA Network Structure
GSM /GPRS BSS
BTS
BSC
PCU
SS7
SCP
SMS
SCE
PSTN/other PLMN
Internet,
Intranet
MSC/VLR GMSC
HLR/AUC
SGSN
CG BG
GGSN
PS backbone
Other PLMN
CS domain
PS domain
NodeB
RNC
UTRAN
Iu-CS
Iu-PS
A
Gb

11. WCDMA Interfaces
A Interface
A-bis
Um
MSC
BSC
BTS
UE
SGSN
Gb
GSM
Iub
Uu
MSC
RNC
NodeB
UE
SGSN
Iu-PSIu-CS
Iub
Uu
RNC
NodeB
UE
Iur
WCDMA
UTRANBSS

12. Scrambling Code
 Scrambling codes
 GOLD sequence.
 Uplink scrambling codes
 Uplink scrambling codes are used to distinguish different UEs
 Downlink scrambling codes
 For downlink physical channels, a total of 218-1 = 262,143 scrambling codes can be
generated.
 Only scrambling codes k = 0, 1, …, 8191 are used.
 8192 codes are divided into 512 groups, each of which contains 16 scrambling codes.
 The first scrambling code of each group is called primary scrambling code (PSC), and the
other 15 ones are secondary scrambling codes (SSC).
 Scrambling code ：GOLD sequence.
 Scrambling code period : 10ms ,or 38400 chips.
 The code used for scrambling of uplink DPCCH/DPDCH may be of either long or short type,
There are 224 long and 224 short uplink scrambling codes. Uplink scrambling codes are
assigned by higher layers.
 For downlink physical channels, a total of 218-1 = 262,143 scrambling codes can be
generated. Only scrambling codes k = 0, 1, …, 8191 are used.

13. Handover
Softer handover
- Handover between intra-frequency cells under the control of the same BTS
- Radio link connection to new target cell is created before existing connection
being deleted.
Soft handover
- Handover between intra-frequency cells under the control of the different
BTSs
Hard handover
- Condition of hard handover:
 Intra-frequency handover, cells controlled by different RNCs and no Iur
interface between them
 Inter-frequency handover
 Inter-system handover
Interruption in voice or data communication occurs but this interruption
does not effect the user communication

14. Principle of RAKE Receiver
RAKE receiver help to overcome on the multi-path fading and enhance
the receive performance of the system
Receive set
Correlator 1
Correlator 2
Correlator 3
Searcher correlator
Calculate the
time delay and
signal strength
Combiner The combined
signal
tt
s(t) s(t)

15. Handover
Softer handover
- Handover between intra-frequency cells under the control of the same BTS
- Radio link connection to new target cell is created before existing connection
being deleted.
Soft handover
- Handover between intra-frequency cells under the control of the different
BTSs
Hard handover
- Condition of hard handover:
 Intra-frequency handover, cells controlled by different RNCs and no Iur
interface between them
 Inter-frequency handover
 Inter-system handover
Interruption in voice or data communication occurs but this interruption
does not effect the user communication

16. Common Pilot Channel
(CPICH)
 Primary CPICH
 Uses OVSF code -Cch, 256,0
 Scrambled by the primary scrambling code
 Only one CPICH per cell
 Broadcast over the entire cell
 The P-CPICH is a phase reference for SCH, Primary CCPCH, AICH, PICH. By
default, it is also a phase reference for downlink DPCH.
 Secondary CPICH
 An arbitrary channel code of SF=256 is used for S-CPICH
 S-CPICH is scrambled by either the primary or a secondary scrambling
code
 There may be zero, one , or several secondary CPICH.
 S-CPICH may be transmitted over part of the cell
 S-CPICH may be a phase reference for S-CCPCH and downlink DPCH.