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RAN TECHNOLOGIES

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3GPP Evolutionary Approach

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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

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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

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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

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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

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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

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HSDPA & HSUPA (HSxPA) Technology Evolution

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Key Characteristics of HSxPA

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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

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End To End Measurement Control of the Subscriber Performance

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What are we doing ?

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What are we doing ?

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RADIO PERFORMANCE DATA ANALYSIS PRE-REQUISITES

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TYPICAL PROBLEMS DURING DRIVE TESTING

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DROP CALL ANALYSIS

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DROP CALL ANALYSIS

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DROP CALL ANALYSIS

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DROP CALL ANALYSIS

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DROP CALL ANALYSIS

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DROP CALL ANALYSIS

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HSDPA Performance Analysis

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Impact of RF on Video Streaming Performance

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Throughput

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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

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