1) How to reduce RRC n RAB failures on parametric level

1) How to reduce RRC n RAB failures on parametric level The main reason for the RRC n RAB failures are - Because of Admission Control - Handover Control - Node B Hardware issues. -Issues with RNC. -Design of the network --pilot pollution So the to reduce the RRC and RAB failures we have to concentrate on the above parameters. 2 ways that may help to reduce the failure that, 1) Increasing the capacity of the Wcell that will reduce the affect of admission control. 2) Try to reduce possible NodeB/RNC hardware issues.

2) how to shift R99 onto hsdpa 2) how to shift R99 onto hsdpa

Release 99 R99 was the first deployment in the UMTS architecture. - In the R99 the High speed channels were not used.So the R99 Downlink throughput offers only up to 384Kbps and Uplink throughput is upto 128Kbps i guess. - The TTI was about 20ms,40ms or 80ms. HSDPA - In HSDPA, A new High speed Transport channel (HS-DSCH) has been added to the WCDMA specification.So this channel is implemented using 3 another Physical channels ie HS-SCCH , HS-DPCCH and HS-PDSCH. So the data rate can be upto 14Mbps IN DL and 5.7Mbps in UL in the release6 (eg) - TTI used is 2ms (Very less compared to R99) -So these 3 High speed channels were not used in the R99 version.

High Speed-Shared Control Channel (HS-SCCH) Uplink High Speed-Dedicated Physical Control Channel (HS-DPCCH) High Speed-Physical Downlink Shared Channel (HS-PDSCH)

At Layer 1, HSUPA introduces new physical channels E-AGCH (Absolute Grant Channel), E-RGCH (Relative Grant Channel), F-DPCH (Fractional-DPCH), E-HICH (E-DCH Hybrid ARQ Indicator Channel), E-DPCCH (E-DCH Dedicated Physical Control Channel) and E-DPDCH (E-DCH Dedicated Physical Data Channel). E-DPDCH is used to carry the E-DCH Transport Channel; and E-DPCCH is used to carry the control information associated with the E-DCH.

HSDPA

16-QAM implies QPSK support, 64-QAM implies 16-QAM and QPSK support. The maximum data rates given in the table are physical layer data rates. Application layer data rate is approximately 85% of that, due to the inclusion of IP headers (overhead information) etc.

HSDPA

TTI

TTI TTI specifies the transmission time Interval between two subsequent TBS's (Transport block Set),transferred between MAC and PHY layer. In the physical layer the TTI identifies the interleaving period.Following TTI periods are currently specified. - 2ms (HS-DSCH in HSDPA) - 10ms - 20ms - 40ms (R99) - 80ms One of the HSDPA propery is the Short 2ms TTI , which reduces the round trip time and improves the tracking of fast channel variations. ie Downlink data is scheduled at 2ms TTI in HS-PDSCH to the users

ABBREVATION

ITU ? International Telecommunication Union UMTS ? Universal Mobile Telecommunication Service PCS ? Personal Communications Services GSM ? Global System for Mobile Communication ISDN ? Integrated Services Digital Network PSTN - Public Switched Telephone Network TDMA ? Time Division Multiple Access FDMA - Frequency Division Multiple Access CDMA ? Code-Division Multiple Access AMPS ? Advanced Mobile Phone Service CDPD ? Cellular Digital Packet Data GPRS ? General Packet Radio Services EDGE ? Enhanced Data for GSM Evolution (or: Enhanced Data GSM Environment) WAP ? Wireless Application Protocol ISM ? Industrial, Scientific, and Medical band

Low HSDAP

1) HSDAP throughput always depends on the number of active HSDPA users in the Wcell. 2)The main parameters that can affect the data rate are Modulation scheme, Number of HS-PDSCH codes, Coding rate, CPICH RSCP, CPICH EcN0, BLER UE Category CQI Distance of the user from the Wcell 3) Poor RSCP and EcN0 can affect the throughput badly. 4) I f the user is in the edge of the Wcell (far form the base station),he cannot expect the throughput as the another user very close to the Wcell (Link Adaptation) 5) Pilot Pollution or the Wcell overlapping also can be the the reason for the low throughput. 6) Iub or Iu-PS congestion can also degrade the HSDPA throughput.

Low HSDAP

These questions were asked 1) Power Control used in WCDMA. 2) Control Channel used in HSDPA 3) What DL/UL throghput am i getting there for HSDPA/HSUPA 4) RRC connection failure reasons. 5)Low throughput reasons for HSDPA

power control used in WCDMA system Mainly 3 types of power control used in WCDMA system 1) Open loop power control 2) Outer loop power control (10HZ-100HZ) 3) Inner loop or Fast closed loop power control (1500HZ in both DL and UL)

1) Open loop power control It is used to provide the initial power settings of the UE at the beginning of a connection.The initial settings happens via RRC signalling. The control is in the UE and RNC. 2) Outer loop power control (10HZ-100HZ) It is performed to adjust the target SIR in the UE/BS. 3) Inner loop or Fast closed loop power control (1500HZ in both DL and UL) WCDMA uses fast power control system in both UL and DL .ie 1500HZ.

power control used in WCDMA system

Uplink-: In the uplink. transmission by the UE must be carefully power controlled so that all the transmissions are received with roughly the same power at the base station. If the power control is not used for UL , near- far problem will occur where the mobile close to the base station will over power the signals from the mobile farther away occurs. The base station uses fast power control to direct mobile to power up or down as its received signal varies due to the changes in the propagation environments. Downlink-: In the DL, we do not have the near-far problem because the one (Node B) to many (UE) scenario. DL inner loop power control is more complex. When the UE receives the transmission of the Node B , the UE returns immediately a transmission power control command to Node B ,telling the Node B to increase or decrease if output power for the UE's DPCH (Dedicated physical channel). The Node B's transmission power can be changed by 0.5,1,1.5 or 2dB. The transmission output power for a DPCH has to be balanced for PICH (Paging Indication Channel), which adds to the power step size. There are two Inner loop power control modes. 1)DPC mode = 0 ; Each time slot a TPC command is sent uplink. 2)DPC mode = 1 ; 3 consecutive time slot for DL, the same TPC command is transmitted. ( TPC - Transmission Power Control)

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Overview of UMTS Architecture

Overview of UMTS Architecture

BLER MEASUREMENT

The TrCH (Transport Channel) BLER (Block Error Ratio) is specied as a parameter as an important indicator of the link quality in UTRAN. Furthermore, the TrCHs in the UMTS system are situated between physical layer and MAC layer [7, 8]. Therefore, the TrCH BLER statistics include a representation of all the physical layer functions as well as the channel characteristics and the properties of inner and outer closed loop TPC (Transmit Power Control) algorithm. At the same time the system level simulator can make use of different parameters for MAC and RLC layer functions. The BLER of the TrCH is thus used as a link between link level simulations or measurements and system level simulations.

BLER MEASUREMENT 3.2 Fixed Bearer vs. Dynamic Bearer Switching A comparison between the measurements for the static case and the measurement data logged in the tramway number two circulating around the rst district of Vienna is presented in Fig. 4. Out of all three networks considered within this measurement campaign, the network of Operator A produces the lowest BLER in case of the `tram2' scenario. The reason for this is that Operator A makes use of dynamic bearer switching in his UMTS network while the others do not. In case of dynamic bearer switching, if there is not enough transmit power available for the link in order to adequately compensate the worsening of the channel for meeting the quality target, the used bearer will be switched down e.g. from 384kbit/s to 128kbit/s bearer. Then with the 128kbit/s bearer the transmission is more robust due to a higher spreading factor and longer TTIs. The TPC again can handle the physical channel variations better by adjusting the link power properly. On the other hand if a xed bearer is used (384kbit/s bearer in our case) like in the networks of operators B and C, the degradation of the physical channel obviously leads to higher BLER for the DCH. Consequently, the network with dynamic bearer switching coarsely provides the same BLER statistics for different levels of coverage in the network in contrast to the networks with a fixed bearer where the BLER will highly depend on the current status of radio access network coverage deployment. Due to that fact, for modelling the error probability of the DL DCH we will only consider measurements of the network with dynamic bearer switching (Operator A) in the following.

BLER MEASUREMENT

4.1 Transport Channel Analysis for Error Modeling Investigating Figs. 5 and 6, small steps in the empirical CDF of the DCH BLER at every 0.5% are visible. The BLER displayed in the diagrams is calculated by building the mean over 2400 transport blocks of the DCH in case of a 384kbit/s bearer. At 0.5% there are exact 12 erroneous transport blocks within the calculation interval. When using the 384kbit/s bearer, there are as well 12 transport blocks transmitted in one TTI. This fact in turn provokes the assumption, that all the 12 erroneous transport blocks causing the BLER of 0.5% belong to the same TTI. When

The histogram in Fig. 7 shows the probability that a certain number of transport blocks are received in error within an erroneous TTI. Of course the probability (probability conditioned on the fact the TTI is in error) to have zero error blocks in a TTI is zero because only erroneous TTIs have been considered. In Fig. 7 can be observed that in case of movements all 12 transport blocks sent within a TTI are in error with a probability of 80% - 85%. Therefore, the errors in UMTS DCH downlink are of a very bursty nature just because most of the times all transport blocks in a TTI are erroneous. Only in the static scenario the probability distribution among the number of error blocks within one TTI is slightly different. These conclusions bring up the following approach for analyzing the measurements to develop a model for DCH BLER.