11 ra4120ben50gla0 initial parameter planning

LTE FDD Initial Parameter Planning

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Additional preamble sequences:

in case the 64 preambles cannot be generated from a single root Zadoff-Chu sequence, then remaining preambles are obtained from the root sequences with the consecutive logical indexes until all the 64 sequences are found.


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• zero correlation zone existence in Zadoff-Chu sequence provides the possibility to decode signals on PRACH even if sent on the same shared resources: on the same frequency and in the same time.

• preamble signals generated based on two different ZC sequences are not correlated within the geographical range related to prachCS (i.e. Cyclic Shift configuration index)

• the size of the cyclic shift, must be larger than the maximum round-trip delay, so prachcs is dependant on the cell radius


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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 is no guarantee that the PRACH will clash in the time domain. It is possible to set different frequency offsets so PRACH doesn’t clash in frequency domain.


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PrachCS also depends on the high speed flag.

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 more root sequences per cell than the needed for certain cell range.


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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 RS are avoided up to 6 adjacent cells ( if 1Tx antenna). For 2Tx ant, # RS is doubled so to avoid collisions in 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 priority If (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 PCImod6 should be different. This is to have frequency shift for RS of different cells, because cells of a given site are frame-synchronized in the sense that DL radio frame transmission starts at the same time instant in all 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 in general 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 with respect 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 there are spots where there is strong interference between RS received from cells of different sites, i.e. RS symbols collide in both time and frequency. If you have a TDD network, this scenario happens probably quite 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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The aggregation level used for Broadcast, Paging Preamble assignment and RA response is specified by 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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The feature allows for creation one or two non-overlapping zones where no uplink PUSCH transmission will take place SRS is automatically disabled

If two PUSCH masks are configured then the ranges {ulsPuschMaskStart .. ulsPuschMaskStart+ulsPuschMaskLength-1} shall not overlap


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11 ra4120ben50gla0 initial parameter planning

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