13 ra4120den30gla0 initial parameter planning gc ppt

7/27/2019 13 RA4120DEN30GLA0 Initial Parameter Planning GC Ppt

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Initial Parameter Planning

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PUSCH Rx power (SINR) can be very high compared to PRACH SINR in the neighbour cell and henceeffectively swamp the PRACH preambles and/or resulting in misdetections (ghost RACH).




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Note: An additional format to these four is specified for TDD

Preamble format 2 supported in RL40




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1 Random access attempt = 1 RACH resource = 6 PRBs

Note: By configuring the PRACH Configuration Indexes at cells belonging to the same site we use the same

subframes for PRACH transmission

Neighbouring eNodeBs are not synchronised so even if the same PRACH configuration indices, there isno guarantee that the PRACH will clash in the time domain. It is possible to set different frequencyoffsets so PRACH doesn’t clash in frequency domain.




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PrachCS also depends on the high speed flag but it is not supported in RL10

Currently the common practice is to assume the same cell ranges for all cells: If all cells are considered

to have the same size, the utilization of root sequences will not be optimal as we will end up using moreroot sequences per cell than the needed for certain cell range.




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Recommendation: Plan different logical root sequence numbers to generate different physical root sequencenumbers.




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First: PSS and SSS signals:

The PSS is generated out of 3 different sequences – each of these sequences indicates one Physical

Layer Cell Identity

The SSS is generated out of 168 sequences – each of these sequences indicates one Physical Layer Cell Identity Group




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ECGI ( E-UTRAN Cell Global Identifier) is used to identify cells globally. It can change (if necessary) once every 80ms but

then it is repeated 3 times before it can be changed again




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Mod3 (PCI):

1.Mod 3 of the PCI is equal to the Physical Layer Cell Identity so if different then PSS signals are

different which facilitates the cell search and synch procedure.

2. RS, carrying one of the 504 PCI has a frequency shift given by mod6(PCI) so collisions between RSare avoided up to 6 adjacent cells ( if 1Tx antenna). For 2Tx ant, # RS is doubled so to avoid collisionsin adjacent cells: mod3(PCI) should be different.

Try to stick to (1) up to (4)If (i) is fulfilled then also (i+1) is fulfilled [for i = 2,3,4]If (i) is not fulfilled then also (i-1) is not fulfilled [for i=3,4]The lower the number the higher the priority, this means (1) has the highest priorityIf (4) is not fulfilled, delta_ss (grpAssigPUSCH) can be used to fix it.

With 2Tx configuration the cells of the same site should have different PCImod3, with 1Tx the PCImod6should be different. This is to have frequency shift for RS of different cells, because cells of a given siteare frame-synchronized in the sense that DL radio frame transmission starts at the same time instant inall the cells --> hence also RS symbols are transmitted at the same time instant. To avoid RS of different cells (of the same site) interfering in the DL, a frequency shift is applied.

The situation changes slightly for cells of different sites, where in RL10 FDD different sites are not ingeneral frame-synchronized (except by chance). In TDD different sites must be frame-synchronized.But in FDD, the DL RS received from cells of two different sites have a random frame offset withrespect to each other and hence the RS symbols may or may not overlap (interfere) in any given

measurement position. But as you said, because of irregular cell shapes, it may well happen that thereare spots where there is strong interference between RS received from cells of different sites, i.e. RSsymbols collide in both time and frequency. If you have a TDD network, this scenario happens probablyquite often. In these cases, perhaps depending on the SINR estimation method used by the particular receiver, the estimation result may be unreliable.




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6 or more PRBs there are two sequences per group, for a given PRB allocation length.

With sequence hopping, there are 2x30=60 sequences for 6 or more PRBs




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If RB allocations is 5 or less, there is only one base sequence per group whereas for allocations of more than 5 PRBs there are 2 RS base sequences per group.




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Table above assumes no quadruplets have been allocated to PHICH and 4x4 MIMO is not used.

Each DCI format includes a 16 bit CRC scrambled by an RNTI. RNTI is used to address the appropriate

UE. RNT also provides indication of the information content of the resource allocation: resources for paging messages on PDSCH, resources for system information messages on PDSCH, resources for application data or signalling, resources for TPC commands.




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The aggregation level used for Broadcast, Paging Preamble assignment and RA response is specifiedby parameters and is limited to aggregation levels 4 and 8 to ensure reliable decoding across the cell

coverage area. The parameters for these along with the recommended values are listed below: pdcchAggPreamb = 4

pdcchAggPaging = 4

pdcchAggRaresp = 4

pdcchAggSib = 4




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Transmission from a single UE




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13 ra4120den30gla0 initial parameter planning gc ppt

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