Transcript Evolution of 2.5G RAN towards the prospects of HSDPA

Final Year Project
Presentation
FYP 08
Arsalan Tariq Mir
Saad Najeeb
Syed Ammar Faheem
Time Line
Comparison
Channel Configurations of WCDMA
Logical Channels
Transport Channels
Physical Channels
Migration Process
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It is a two step process,
– the first step involves the introduction of UMTS networks which involves
a hardware change to the RAN network as new WCDMA air-interface is
introduced.
– the second step is a software upgrade to the RNC of WCDMA RAN.
Planning Phases
Network Planning
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WCDMA technology has set new requirements to radio network planning
All frequency dependent elements have to be updated and taken into
account during planning (antennas, cables, power amplifiers, low noise
amplifiers, filters, combiners…)
WCDMA operates in the frequency band of 2100 MHz, which is much more
higher than the 900 MHz and 1800 MHz typically in GSM
All the WCDMA cells can use the same frequency -> reuse = 1
Interworking between WCDMA and GSM has to planned
Code and Frequency planning
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In WCDMA networks, cells are identified by:
– Unique cell ID
– Frequency
– Scrambling code
Scrambling code optimization is an important task in designing and
deploying a WCDMA network.
The total primary scrambling codes available in the WCDMA system is 512.
Individual cells use channelization codes to separate users and
communication channels:
– All mobiles share the same frequency carrier.
– Cells use orthogonal channelization codes to separate users and
separate communication channels
Example Scrambling Code Optimization
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The following figure shows an example of scrambling code optimization.
The cell scrambling code is the figure adjacent to the cell symbol. Each cell
in this example is assigned a unique scrambling code.
HSDPA Basics
• Described in 3GPP Release 5 specifications
– Enhances peak download data rate from current 384 kbps up to a
theoretical maximum downloading peak rate of 14.4 Mbps (10,7 Mbps
with ¾ coding rate)
– Aimed for interactive and background services but streaming is also
considered
• Requires investments to R99/R4 UMTS (WCDMA) network
– Affects radio network HW and SW, core network SW, and transmission
network HW
– Can be deployed using small upgrades, not required for all BSs, RNCs
– Does not require a completely new network structure
– Protecting the current investments made to the network
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In order to reduce Round Trip Time (RTT) new features have been implemented in BS, closer to
the air interface
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Adaptive Modulation and Coding (AMC)
– Depending on UE channel conditions (CQI)
– QPSK, 16QAM
– Coding rate (1/4 – 3/4)
– Data rate adapted on 2 ms time basis
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Fast Retransmission
– Hybrid Automatic Repeat reQuest (HARQ)
– UE soft-combines data
– Reduced RTT
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Fast Packet Scheduling (PS)
– Scheduling of users on 2 ms time basis
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New radio channels included for HSDPA
– DL: HS-(P)DSCH, HS-SCCH
– UL: HS-DPCCH
Thank You!