UMTS simulator

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UMTS simulator

• Alberto Bona, Maurizio Conti

Politecnico di Torino
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Scenario(1)

• General Assumption
• Simulator time step is equal to 1 frame (10 ms)
• Advantages
• Bit rate can be varied every TTI
• Transport channel accuracy
• Simpler and faster
• Limitations
• Power control is slot based ? neglected
• RACH and CPCH collisions are modelled on a frame
  basis

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Alberto Bona, Maurizio Conti
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Scenario(2)

• 1 RNC ? SRNC ? CRNC
• Simulation of intra-RNC handover is possible
• Simulation of inter-RNC handover is not precluded
• Node-B number is an input parameter
• Node-B inherits generic-BTS behaviour adding UMTS
  features
• Structure is adherent to UMTS standards

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Scenario(3)

• RNC maintains (UTRAN-side) peer-UE protocol
  instantiation
• RNC creates RRC layer which is responsible for
  channel allocation
• RNC maintains UE schedulation references
• Each Node-B has a MAC_CSH entity responsible for
  common transport channel transmission and
  reception

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Protocol implementation(1) RACH

• Its an uplink transport channel
• Slotted-aloha based, allows transmission of 1
  frame
• UE has to restart access procedure for each
  transmission
• RACH will be used for low bit-rate data
  transmissions which dont need high throughput

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Protocol implementation(2) CPCH

• Its an uplink transport channel
• Slotted-aloha based with fast acquisition
  indication and collision detection
• UE, once access has been completed, is the owner
  of the code for NMAX consecutive frames
• CPCH will be used for data transmissions which
  require higher throughput

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Alberto Bona, Maurizio Conti
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Protocol implementation(3) DSCH

• Its a downlink transport channel
• UE share the same code, multiplexed on a frame by
  frame basis
• UE multiplexing is granted through polling on a
  signalling channel (at present Round Robin)
• DSCH will be used for non real time traffic WWW,
  FTP...

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UE-structure (MAC_D)

• RB_mapping_info data (priority, log-CH_ID) for
  log-CH to tr-CH mapping
• C/T switch routes PDU towards TX buffers
• TX buffers on DCH or on common tr-CH
• DCH TF Transport Format for DCH variable every
  TTI
• C/T demux allows demultiplexing of blocks from
  tr-CH to log-CH

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UE-structure (MAC_CSH)

• TCTF-Insert data and signalling multiplexing on
  transport channels
• TX Buffers on RACH and CPCH
• RACH and CPCH TF TF for transport channels
• TCTF-Read data (towards MAC_D) and signalling
  blocks demultiplexing

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UTRAN-structure (MAC_CSH)

• Sheduling-Priority Handling selects UE for TX on
  common transport CH.
• Controllers
• RACH manages collisions with a frame based model
• CPCH manages collisions (as RACH) and provides
  codes for UE transmissions
• MAC_D list maintains info about UE under Node B
  control

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UMTS validation tests and simulations

• Alberto Bona, Maurizio Conti

Politecnico di Torino
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Validation tests RACH

• Transfer delay has constant characteristics
• Increasing UE number, arrived packets decrease
  because of collision
• Mean transfer delay is independent by UE number

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Alberto Bona, Maurizio Conti
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Validation tests CPCH

• 1 IP packet is transferred releasing signature ?
  more than 1 max in picture
• 1 IP packet needs 3 signature allocation to be
  transferred
• time between max is due to signature contention
  or lack of codes

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UMTS traffic sources

• Based on UMTS 30.03
• 25 packet per ON session OFF session 3 s
• 480 byte per packet
• UDD64
• constant interarrival time between packets 62.5
  ms
• 2 blocks per frame
• 320 bit per block
• UDD144
• constant interarrival time between packets 27 ms
• 4 blocks per frame
• 360 bit per block

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RACH Results collision probability
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RACH Results throughput
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CPCH Results blocking probability
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CPCH Results throughput
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CPCH Results MAC transfer delay
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DSCH Results throughput-UDD144
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DSCH Results MAC transfer delay
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GPRS-UMTS Comparison(1)

• GPRS model 1 PDCH signalling, 7 PDCH data,
  dynamic allocation, Round Robin scheduling
• UMTS model 3 codes per transport channel
• Traffic source UDD64

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GPRS-UMTS Comparison(2)
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GPRS-UMTS Comparison(3)
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