2 umts key technologies
TRANSCRIPT
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 1/80
UMTS Key Technologies
ZTE University
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 2/80
Content
RAKE Receiver
Handover Control
Compressed Mode
Admission Control Load Control
Code Resource Allocation
Capacity Features
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 3/80
Multi-path characteristics of radio channel
Electromagnetic propagation: direct radiation、reflection、diffraction and scattering
Signal attenuation:
Path loss: Loss of electromagnetic waves in large scope of the
spread reflects the trend of the received signal in the spreading。
Slow fading:Loss because of being blocked by the building and
hill in the propagation path
Fast fading:Electromagnetic signals rapidly decline in a few
dozens wavelength ranges
Description of Fast fading distribution Rayleigh distribution:non line-of –sight(NLOS) transmission
Rician distribution:line-of –sight(LOS) transmission
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 4/80
Multi-Path Effects
time
strength
0
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 5/80
Frequency off-set caused by the movement of mobile that
is Doppler effect
Sending signal Accepting signal
Interference
0dB
Sending signal
-25dB
Accepting signal
fading
0 +
Sending signal Accepting signal
delay
0 2 3 +
Sending signal Accepting signal
dithering
Characteristics of Radio Propagation
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 6/80
RAKE Receiver can effectively overcome the multi-path
interference, consequently improve the receiving performance.
RAKE Receiver
The multi-path signals contain some useful energy ,therefore the UMTS receiver can combine these energy of
multi-path signals to improve the received signal to noise
ratio.
RAKE receiver adopts several correlation detectors to
receive the multi-path signals, and then combines the
received signal energy.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 7/80
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 8/80
Multi-finger receiver
Traditional receiver Multi-path signals are treated as interference.
The receiving performance will decline because of the
Multi-address Interference (MAI).
Precondition of Multi-finger receiver Multi-finger receiver utilizes the Multi-path Effect.
Multi-finger signals can be combined through relative
process
Multi-finger time delay is larger than 1 chip interval,
which is 0.26us=>78m.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 9/80
Multi-finger receiver
receiver transmitter
coding decoding
Direct signal
Reflected signal
Dispersive time < 1 chip interval
Multi-finger receiver can’t supply multi-finger diversity
decoding
Direct signal
Reflected signaltransmitter receiver
Dispersive time > 1 chip interval
Multi-finger receiver can supply multi-finger diversity, signal gain is improved
coding
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 10/80
RAKE Receiving
receiver
Single
receiving
Single
receiving
Single
receiving
searcher calculate
combining
t t
s(t) s(t)
signal
RAKE Receiving overcomes multi-finger interference, improvesreceiving performance
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 11/80
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 12/80
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 13/80
What’s ?
When UE is moving from the coverage area of one site to another, or the quality of service is
declined by external interference during a service,
the service must be handed over to an idle
channel for sustaining the service. Handover is used to guarantee the continuity of
service
Handover is a key technology for mobilenetworking
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 14/80
Category of Handover
Intra-RNC, inter-Node B
Inter-RNC
Soft handover (SHO)
Same Node B, Inter-sector
Softer handover
Intra-frequency
Inter-frequency
Inter-system (3G&2G)
Inter-mode (FDD&TDD)
Hard handover (HHO)
UMTS system support
multiple handover technology
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 15/80
Handover Demonstration
Hard
Handover
Soft
Handover
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 16/80
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
Soft Handover/Softer Handover
Soft Handover
Soft-Softer Handover
Softer Handover
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 17/80
Hard Handover
During the hard handover procedure,all the old radio links with the UE are
abandoned before new ones are
established, so there must be
service interruption during the HHO.
Hard handover may occur in the
following main cases
When the UE is handed over to another
UTRAN carrier, or another technology
mode. When soft handover is not permitted (if
O&M constraint)
Hard Handover
Node B
SRNC
RNC or
BSC
CN
Node B orBTS
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 18/80
Soft/Softer Handover
The soft/softer handover allows to migrate from one cell toanother without service interruption or without deleting all
old radio links.
UE can connecte to more than one cell simultaneously and
take benefit from the macro-diversity.
Soft Handover Softer Handover
CN CN
Iur
The two Node Bsmay belong to the
same RNC
The two Node Bs maybelong to the Same RNC
Soft Handover Softer Handover
SRNC DRNC
CN
Node B
SRNC
CN
Soft Handover Softer Handover
Node B
CN
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 19/80
UMTS General Handover Trilogy
Measurement Control UTRAN demands the UE to start measurement through
issuing a measurement control message.
Handover decision
UTRAN makes the decision based on the measurementreports from UE. The implementation of handover
decision is various for different vendors. It impacts on
the system performance critically.
Handover execution UTRAN and UE execute different handover procedure
according to the handover command.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 20/80
(A) RNC sends measurement
control message to UE
(Measurement Control)
(B) UE starts measurement task
with the parameters included in
the message, and reports
measurement results(
Measurement Report)
(C) RNC stores the
measurement results according
to frequencies and cells
(D) RNC Estimates the quality
of each carrier (including intra-
frequency and inter-frequency)
(E) Quality
Decision
(G) Allocate resource
in target cell, prepare
to execute handover
(F) maintain the
active set and
monitored set
(H) Allocate
resource in target
cell, prepare to
execute handover
Currentcarrier has
good quality
Othersystem has
good
qualityOther carrier has good
quality
(I)If handover is required, RNC sends
handover command with target cell to UE
Handover Flows
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 21/80
General Procedure of Handover Control (I)
Measuring The measurement objects are decided by RNC. Usually,
either Ec/No or RSCP (Received Signal Code Power) of P-
CPICH channel is used for handover decision.
ZTE RNC adopts Ec/No measurement, because Ec/Noembodies both the received signal strength and the
interference. The relation of Ec/No and RSCP is shown as
follows:
Ec/No=RSCP/RSSI
In the above equation,RSSI(Received Signal Strength
Indicator )is measured within the bandwidth of associated
channels
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 22/80
Filtering
The measurement results should be filtered before being
reported. Measurement filtering can be regarded as a low pass
filtering procedure. The following equation is applied for filtering.
Fn=(1-a)Fn-1+a*Mn
Variants definition: Fn:filtered measurement result;
Fn-1:last filtered measurement result;
Mn:latest Ec/Io or RSCP measurement result received from
physical layer;
a = 1/2(k/2), k means the “Filter coefficient”, which is included in theMeasurement Control message. It is decided by the UTRAN.
F0 is initialized by the first measurement result M1.
General Procedure of Handover Control (II)
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 23/80
General Procedure of Handover Control (III)
Reporting Period report triggered handover
Base on the filtered measurement result
Event report triggered handover
Base on the event
Soft
Handover
Hard
Handover
Period
Event
Measurement result filtered in UE
Event decided in RNC
Handover decided in RNC
Measurement result filtered in UE
Event decided in UE
Handover decided in RNC
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 24/80
General Procedure of Handover Control (IV)
Handover algorithm All the handover algorithms including soft handover,
hard handover and so on are implemented on the event
decision made according to the measurement reports.
Events defined in 3GPP specifications Intra-frequency events:1A~1F
Inter-frequency events:2A~2F
Inter-RAT events:3A~3D
Note: RAT is short for “Radio Access Technology”, e.g.
UMTS&GSM
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 25/80
Concepts Related to Handover
Active Set: A set of cells that have established radio links with a
certain mobile station.
User information is sent from all these cells.
Monitored Set: A set of cells that are not in the active set but are
monitored according to the list of adjacent cells
assigned by the UTRAN.
Detected Set:
A set of cells that are neither in the active set nor in the
monitor set.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 26/80
Configuring Priority for Each Cell
Source Cell
Priority 0
Priority 1
Priority 2
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 27/80
Tactics of Deleting Neighboring Cells in Excess of 32
The protocol specifies the upper limit of co-frequency
neighboring cell quantity to be 32 (including source
cells). When the UE is in the macro diversity state, the
quantity of neighboring cells of multiple cells in the
macro diversity may exceed the upper limit. Therefore,a tactic is required to delete the excessive neighboring
cells. The tactics are: combining and adjusting priority
levels, selecting the cell among the cells of the same
priority, and deleting excessive neighboring cells.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 28/80
Tactics of Deleting Neighboring Cells in Excess of 32
Combining priority levels
If a cell is adjacent to multiple cells in an active set, the cell
may have different priority levels configured by the
background when it is adjacent to different cells. In this case,
the multiple priority levels will be combined, and the highest
priority level among them will apply.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 29/80
Tactics of Deleting Neighboring Cells in Excess of 32
Updating the Adjacent Cell List and Deleting Neighboring
Cells in Excess of 32 If there are more than 32 neighboring cells in the neighboring cell
list of an active set, the neighboring cells will be arranged from the
high priority level to the low priority level. The cells subsequent to
the 32nd cell will be placed into the neighboring cell reservation list. When triggering event 1a, 1b, 1c or 1d, the UE updates the priority
level of neighboring cells in the neighboring cell list. After event 1b
occurs, if there are less than 32 neighboring cells in the
neighboring cell list, the UE will select the neighboring cells from
the high priority level to the low priority level in the neighboring cellreservation list, and put the selected cells into the neighboring cell
list. The quantity of cells that can be selected is: min (32 – quantity
of cells existent in the neighboring cell list, quantity of cells in the
neighboring cell reservation list).
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 30/80
Soft handover event
Event Description
1AQuality of target cell improves, entering a
report range of relatively activating set quality
1B Quality of target cell decreases, depart from areport range of relatively activating set quality
1CThe quality of a non-activated set cell is better
than that of a certain activated set cell
1D Best cell generates change
1EQuality of target cell improves, better than an
absolute threshold
1FQuality of target cell decreases, worse than
an absolute threshold
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 31/80
An Example of SHO Procedure
Pilot Ec/Io of cell 1
time
Pilot
Ec/Io
Connect to cell1 Event 1A Event 1C Event 1B
(add cell2)(replace cell1 with cell 3)(remove cell3)
Pilot Ec/Io of cell 2
Pilot Ec/Io of cell 3
⊿t ⊿t ⊿
t
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 32/80
RNS Relocation
Core NetworkCore Network
Serving
RNSTarget
RNS
Serviing
RNSTarget
RNS
Iu Iu
Iur
RNS
Radio Network Sub-system
RNS relocation can :
Reduce the Iur traffic significantly
Enhance the system adaptability
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 33/80
Hard Handover
Hard handover measurement is much more complex for UE than soft handover measurement.
Inter-frequency hard handover requires UE to measure the
signal of other frequencies.
UMTS employs compressed mode technology to supportinter-frequency measurement.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 34/80
Content
RAKE Receiver Handover Control
Compressed Mode
Admission Control Load Control
Code Resource Allocation
Capacity Features
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 35/80
Purpose of Compressed Mode
In order to support inter-frequency and inter-RAThandover, UE is required to perform inter-frequency
and Inter-RAT measurement periodically.
The UE with one transceiver does not have the
opportunity to perform inter-frequency measurement
during the service period (especially the voice call) ,
because the transceiver is busy in transmitting and
receiving the signals all the time.
Compressed mode can provide idle slot based
transmission time window, which can be used for inter-frequency measurement, for the UEs in
connected state, e.g. CELL_DCH.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 36/80
Compressed Mode
Compressed Mode Transmission Diagram
Transmit gaps(Maximum 7 slots = 4.7ms) 1 frame(10ms)
10ms
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 37/80
Generation of Compressed Mode Frame
Puncturing
Lower the symbol rate of physical channel when
processing the rate matching procedure
SF halving Employ half SF, e.g. employ SF64 to replace
SF128
High layer scheduling
Decrease the bit rate from up layer
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 38/80
Content
RAKE Receiver Handover Control
Compressed Mode
Admission Control Load Control
Code Resource Allocation
Capacity Features
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 39/80
Admission Control
The admission control is employed to admit the access of
incoming call. Its general principal is based on the
availability and utilization of the system resources.
If the system has enough resources such as load margin,
code, and channel element etc. the admission control will
accept the call and allocate resources to it.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 40/80
Purpose of Admission Control
When user initiates a call , the admission control should
implement admission or rejection for this service according
to the resource situation.
The admission control will sustain the system stability
firstly and try the best to satisfy the new calling service’s
QoS request, such as service rate, quality (SIR or BER),
and delay etc. basing on the radio measurement.
Admission control is the only access entry for the incoming
services, its strategy will directly effect the cell capacity
and stability, e.g. call loss rate, call drop rate.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 41/80
Admission Control in Uplink
I total_old +ΔI >I threshold
The current RTWP (Received
Total Wide Power) value of cell,
which is reported by Node B
Access
Threshold
Interference capacityService priority
Reserved capacity for
handover
I own-
cell
0
~ N
I other- cell
The forecasted interference including the deltainterference brought by the incoming service is
calculated by the admission algorithm, and its
result depends on the QoS and transmission
propagation environment
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 42/80
Different ultimate user numbers
Different interference threshold under different ultimate
user number conditions
Different ultimate throughputs
Quantity of Subscriber
Quantity of Subscriber-- The Total Bandwidth Received by Node B
T h e T o t a l B a n d w i d t h P o w e r R e c e i v e d b y N o d e B ( d B m )
Ultimate Situation for different service rate
Throughput
Throughput -- The Total Bandwidth Received by Node B
T h e T o t a l B a n d w i d
t h P o w e r R e c e i v e d b y N o d e B ( d B m )
Admission Control in Uplink
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 43/80
Admission Control in Downlink
P total_old + △P>=P threshold Access
Threshold
The forecasted TCP value including deltapower required for the incoming service is
calculated by the admission algorithm, and its
result depends on the QoS and transmission
propagation environment.
The current TCP value of cell, which is reported by Node B
(Transmitted Carrier Power*Pmax)
Max TCP of cellService priority
Reserved capacity for
handover
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 44/80
Quantity of Subscriber
T h e T o t a l T r a n s
m i s s i o n P o w e r ( d B m )
Red:low speed serviceBlue:high speed service
The above figure illustrates the relation between ultimate user number
corresponds to different service rate and distance under equidistant
distribution condition
Admission Control in Downlink
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 45/80
The service can be either one-direction or bi-directiontype. For bi-direction service, it is admitted only after
both uplink and downlink are admitted.
Admission control is the only access entry for the
incoming services, its strategy will directly effect the
cell capacity and stability, e.g. call loss rate, call drop
rate.
Admission Control Analysis
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 46/80
Content
RAKE Receiver Handover Control
Compressed Mode
Admission Control Load Control
Code Resource Allocation
Capacity Features
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 47/80
Load control
The purpose of load control is to keep the
system load under a pre-planned threshold
through several means of decreasing it, so as to
improve the system stability.
The speed and position
changing of UE may
worsen the wireless
environment.
Increased transmitted
power will increase the
system load.
Purpose of Load Control
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 48/80
Overload control
Serious overload threshold
Overload recovery threshold
Admission control threshold
Common overload threshold
Cell load
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 49/80
Overload control
Normalstate
Commonoverload
state
Seriousoverload
state
4. The load is smaller than theoverload recovery threshold
3. The load exceeds the serious overload threshold
6. The load is smaller than the serious overload threshold.but greater than the common overload threshold
5. The load exceeds theserious overload threshold.
1. The load exceeds thecommon overload threshold
2. The load is smaller than the
overload recovery threshold
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 50/80
Load Control Flows
Start
DecisionLight loaded Over loaded
Normal loaded
Handover in and
access are forbidden
TCP increase isforbidden
RAB service rate
degrade
4. Handover out
5. Release call (call drop)
1. Handover in and access
are allowed
2. Transmitted code power (TCP) increase is allowed
3. RAB service rate
upgrade is allowed
. Handover in
and access are
allowedTCP increase
is allowed
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 51/80
Load Control in Uplink
Triggers
RTWP (Received Total Wide-band Power) value from
measurement report exceeds the uplink overload threshold;
Admission control is triggered when rejecting the access of
services with lower priority due to insufficient load capacity in uplink.
Methods for decreasing load Decrease the target Eb/No of service in uplink;
Decrease the rate of none real time data service;
Handover to GSM system;
Decrease the rate of real time service, e.g. voice call; Release calls.
Methods for increasing load
Increase the service rate.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 52/80
Load Control in Downlink
Triggers TCP (Transmitted Carrier Power) value from measurement report
exceeds the downlink overload threshold;
Admission control is triggered when rejecting the access of services with lower priority due to insufficient load capacity indownlink.
Methods for decreasing load Decrease the downlink target Eb/No of service in downlink;
Decrease the rate of none real time data service;
Handover to coverage-shared light loaded carrier;
Handover to GSM system;
Decrease the rate of real time service, e.g. voice call;
Release calls.
Methods for increasing load Increase the service rate.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 53/80
Cell breathing isone of the means
for load control
The purpose of cell breathing is to share the load of hot-
spot cell with the light loaded neighbor cells, therefore to
improve the utilization of system capacity.
Cell Breathing Effect
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 54/80
Example for load control
Cell Breathing Effect With the increase of activated
terminals and the increase of high
speed services, interference will
increase.
The cell coverage area will shrink. Coverage blind spot occurs
Drop of call will happen at the edge
of cell
Coverage andcapacity areinterrelated
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 55/80
Content
RAKE Receiver Handover Control
Compressed Mode
Admission Control Load Control
Code Resource Allocation
Capacity Features
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 56/80
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 57/80
Function of OVSF Code
OC1, OC2
OC3, OC4
OC5, OC6, OC7
OC1 , OC2, OC3
OC1, OC2
OC1, OC2, OC3, OC4
Uplink: distinguish different radio channels from the same UE.
Downlink: distinguish different radio channels from the same NodeB.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 58/80
Function of Scrambling code
Downlink: distinguish different Cells
Uplink: distinguish different UEs
PN3 PN4
PN5 PN6
PN1 PN1
Cell Site “1” transmits using PN code 1
PN2 PN2
Cell Site “2” transmits using PN code 2
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 59/80
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 60/80
Code Resource Planning
The uplink and downlink scrambling code can be planned
easily by computer.
The uplink channelized code does not need planning, for every UE can use the whole code tree alone.
Therefore, only the downlink channelized code is planned
with certain algorithm in RNC. Each cell has one primary scrambling code, which
correlates with a channel code tree. All the users under this cell share this single code tree, so the OVSF coderesource is very limited.
The downlink channelized code tree is a typical binary treewith each layer corresponds to a certain SF ranging fromSF4 to SF512.
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 61/80
SF = 1 SF = 2 SF = 4
Cch,1,0 = (1)
Cch,2,0 = (1,1)
Cch,2,1 = (1,-1)
Cch,4,0 =(1,1,1,1)
Cch,4,1 = (1,1,-1,-1)
Cch,4,2 = (1,-1,1,-1)
Cch,4,3 = (1,-1,-1,1)
Generation of Channelized Code
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 62/80
OVSF Code Tree
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 63/80
SF=8
SF=32
SF=16
Channelized Code Characters
Code allocation restriction:
The code to be allocated must fulfill the condition that its
ancestor nodes including from father node to root node
and offspring nodes in the sub tree are not allocated;
Code allocation side effect:
The allocated node will block its ancestor nodes and
offspring nodes, thus the blocked nodes will not be
available for allocation until being unblocked .
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 64/80
A E l f C d All i
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 65/80
An Example of Code Allocation
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SF = 4
SF = 8
SF = 16
SF = 32
SF = 4
SF = 8
SF = 16
SF = 32
Red spots represent the codes that have been allocated
Green spots represent the codes that are blocked by the allocated offspring codes
Blue spots represent the codes that are blocked by the allocated ancestor codes;
Black spots represent the codes that to be allocated;
Choose one
code from
three
candidates
Pl i f d li k bli d
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 66/80
Planning of downlink scrambling code
PN1
PN2
PN3PN7
PN6 PN4
PN5
PN7
PN6 PN4
PN5
PN1
PN2
PN3
PN1
PN2
PN3PN7
PN6 PN4
PN5
PN1
PN2
PN3PN7
PN6 PN4
PN5
PN1
PN2
PN3PN7
PN6 PN4
PN5 PN1
PN2
PN3PN7
PN6 PN4
PN5
C t t
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 67/80
Content
RAKE Receiver Handover Control
Compressed Mode
Admission Control Load Control
Code Resource Allocation
Capacity Features
C it f UMTS
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 68/80
Capacity of UMTS
P Ri i
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 69/80
Power Rising
Power rising occurs because of the Multiple Access
Interference (MAI) resulting from the non-orthogonal
code channels.
UMTS network Meeting Room
Code channel transmit talk with dialects
Channel power voice tone
Promised channel quality listen clearly
Channel power rise voice tone rise
Power climb voice climb
Collapse over the range can not hear each other
P Ri i
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 70/80
Power Rising
Quantity of Subscriber
Quantity of Subscriber-- The Total Bandwidth Received by Node B
T h e T o t a l B a n d w i d t h P o w e r R e c
e i v e d b y N o d e B ( d B m
)
C it f UMTS S t
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 71/80
Capacity of UMTS System
Under the circumstance of single services:
=
=
=
C it f UMTS S t
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 72/80
Capacity of UMTS System
…...
+ +
Under the circumstance of mixed services:
UMTS C it F t
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 73/80
UMTS Capacity Features
UMTS capacity feature
UMTS capacity is Soft Capacity.
The Concept of Soft Capacity
The system capacity and communication quality are
interconvertible. Different services have different capacity.
Different proportion of services have different capacity
for mixed services.
The capacity is also restricted to the allocation of coderesource.
Concept of Soft Capacit
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 74/80
Different combinationof service hasdifferent capacity
Concept of Soft Capacity
System capacity and QoS can be interconverted
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 75/80
Coverage and Capacity
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 76/80
Coverage and Capacity
UMTS performance is determined by such factors
as: Number of users
Transmission rate
Moving speed
Wireless environment indoors
Outdoors
The radius of cell depends on such factors as: Local radio conditions (local interference) Traffic in neighbouring cells (remote interference)
Cell Radius decrease according to the Increase of user number
Coverage/capacity VS Data Rate
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 77/80
Coverage/capacity VS Data Rate
Higher data rate needs higher power
High data rate transmission is only available nearby the
station
>12.2 kbps
>64 kbps
>384 kbps
>144 kbps
Coverage decrease
Subscriber
numincrease
Optimization methods
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 78/80
DL/UL: Add carrier
six sectors
UL
Tower Mounted Amplifier (TMA)
4 Rx Div
OTSR
DL transmission diversity (Tx Div)
high power amplifier
Add basestation
“last choice”
Optimization methods
To overcome Cell Breathing Effect caused by increased
traffic and meet different requirements for capacity and
coverage in different environment, following solutions can
be applied:
Factors affects UMTS Capacity
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 79/80
Factors Impact on UMTS capacity
RAKEReceiver The advanced receiving and baseband processingtechnology is introduced to overcome the fast fading
Power Control Reducing interference, saving power and Increasing capacity
HandoverControl
Impacting the capacity through applying different proportion
and algorithm of soft handover
AdmissionControl
Admitting a connection base on the load and the admission
threshold of planned capacity
Load ControlMonitoring system load and adjusting the ongoing services to
avoid overload
OVSF Code The Allocation of codes impacts the maximum number of simultaneous connections.
WirelessEnvironment
Wireless environment such as interferences, UE position and
mobility etc. can influent the cell capacity
Factors affects UMTS Capacity
7/30/2019 2 UMTS Key Technologies
http://slidepdf.com/reader/full/2-umts-key-technologies 80/80