ran technologies - burakkurt.net · eachcarrier supports 8 speech channels using tdma gaussian...
TRANSCRIPT
C1
RAN TECHNOLOGIES
C1
3GPP Evolutionary Approach
2
C1
GSM – 2nd Generation Standart
Each carrier supports 8 speech channels using TDMA
Gaussian Minimum Shift Keying (GMSK) is a form of
frequency shift keying known for its power efficiency
• EDGE System 8 state phase shift keying is employed, this
permits 3 times the data rate to be sent within the same
bandwidth
• Speech Channel: Data rate was 13 kbit/s
• Data Channel (8 PSK): 48 kbps/timeslot
• Maximum Data Throughput: 48 * 8 ~ 384 kbps
3
C1
UMTS – 3rd Generation Standart
Wideband Code Division Multiple Access (WCDMA) allows
man y subscribers to use the same frequency at the same
time
In order to distinguish between users, the information
undergoes a process known as spreading that is the
information is multiplied by channelization and scrambling
codes
Spreading is a method of increasing the occupied spectrum
by multiplying data by a spreading code and thus enabling
very low SNR or C/I levels to be tolerated
The technology was first developed by the military to avoid
the possiblity of their signals being jammed or listened to by
the enemy
4
C1
Processing Procedure of WCDMA System
• Bit : data after source coding
• Symbol: data after channel coding and interleaving
• Chip: data after spreading
• Spreading Code = Scrambling code + Channelization code
• Chip Rate for the system is 3.84Mchips/s and signal is spread in 5 Mhz
• Spreading Factor (SF) is the ratio between the chip rate and the symbol rate
5
C1
Channelization Codes
The channelization codes are Orthogonal Variable Spreading Factor (OVSF) codes.They are used to preserve orthogonality between different physical channels.
• For voice service (AMR), downlink SF is 128, means max 128 voice services can besupported in one WCDMA carrier.
• 4 users sending at SF=8 and 1 user sending at SF=2
6
C1
WCDMA Self Interfering System
Spreading process increases the bandwidth and reduces thepower density of the signal
• Interference from other users within the cell and also from othercells form the transmitted signal spectrum .
• After despreading the wanted signal benefits from theprocessing gain whereas the interference passes through largelyunchanged
• The power requirement determines the service coverage inWCDMA. Users will require different amount of power andcapacity depending on environment, service, system load
InterferingSignals
Desired Signal
The service coverage shrinks with increasing traffic in the cell
7
C1
HSDPA & HSUPA (HSxPA) Technology Evolution
8
C1
Key Characteristics of HSxPA
9
C1
MODULATION THROUGHPUT WITH 5 CODES
THROUGHPUT WITH 10 CODES
THROUGHPUT WITH 15 CODES
QPSK
600 kbps 1.2 Mbps 1.8 Mbps
1.2 Mbps 2.4 Mbps 4.8 Mbps
1.8 Mbps 3.6 Mbps 5.4 Mbps
16QAM
2.4 Mbps 4.8 Mbps 7.2 Mbps
3.6 Mbps 7.2 Mbps 10.7 Mbps
4.8 Mbps 9.6 Mbps 14.4 Mbps
Code and Modulation Affect on HSDPA Throughput
10
C1
End To End Measurement Control of the Subscriber Performance
11
C1
What are we doing ?
12
C1
What are we doing ?
13
C1
RADIO PERFORMANCE DATA ANALYSIS PRE-REQUISITES
14
C1
TYPICAL PROBLEMS DURING DRIVE TESTING
15
C1 16
C1 17
C1
DROP CALL ANALYSIS
18
C1
DROP CALL ANALYSIS
19
C1
DROP CALL ANALYSIS
20
C1
DROP CALL ANALYSIS
21
C1
DROP CALL ANALYSIS
22
C1
DROP CALL ANALYSIS
23
C1
HSDPA Performance Analysis
24
C1
Impact of RF on Video Streaming Performance
25
C1
Throughput
26
C1
3G Coverage Loss @Loaded Hours
Desciption:
Cell coverage shrinks called Cell Breathing is integral to WCDMA cellular radio systems. Itsdisadvantage is that it leads to the creation of gaps in the network coverage. The amount ofcell breathing can be controlled by limiting the NoiseRise in the admission algorithm. Itcannot, however be eliminated.
Optimization Actions Finalized: Tilt revisions Neighbor Relation Revisions Power Increase
Planned Actions: Parameter change for GSM to UMTS cell relection
fdd_qmin = -8 -12 ( To increase the possibility of selecting UMTS network especially during loaded times )
Analysis for feasibility of Second Carrier Activation for capacitive reasons
For Samsun City: A new nomial plan will be run as a trial with Nw. Ran. Pl. considering parameters for real network conditions: traffic and load
Analysis Case:An internal VIP customer raises an issue regarding coverage loss of 3G network and alwaysbeing in 2G connected mode during network loaded hours ( noise rise ) and could onlyaccess to 3G network during non loaded hours at a specific location.
Limiting the Noise Rise to 3 dB will restrict throughput to 50% of
theoretical maximum and restrict coverage shrinkage to 33% of its
maximum area.
Remarks:
Starting with RF optimization, improvement is seen in 3G signal and quality level as well as atthroughput at the location during loaded hours. A planning and optimization consideration isnecessary against 3dB noise rise for the provision of current and extra sites.
Unloaded Coverage
Unloaded Coverage
loaded Coverage
loaded Coverage
Drive Test Before Optimization:Unloaded times:
Radio Quality: -11.00 CPICH Ec/NoRadio Coverage: -85dBm RSCPThroughput: 1.4mbps dl
Loaded times:Radio Quality: -12.50 CPICH Ec/NoRadio Coverage: -92dBm RSCPThroughput: 1.1mbps dl
Drive Test After Optimization:Unloaded times:
Radio Quality: -8.50 CPICH Ec/NoRadio Coverage: -82dBm RSCPThroughput: 2.7mbps dl
Loaded times:Radio Quality: -9.50 CPICH Ec/NoRadio Coverage: -80dBm RSCPThroughput: 2.1mbps dl
C1 28
C1 29