Cell Radius in LTE (Part 1 of 3)

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Cell Radius in LTE (Part 1 of 3)

  • Comments 3

 

The cell radius in LTE is affected and/or determined by three factors:

a) The Preamble Format

b) The Cyclic Shift the corresponds to the ZeroCorrelationZoneConfig parameter and,

c) The Cell Radius Parameter

 

A) Preamble Format

LTE FDD supports four preamble formats (as of today, not all of them currently supported by the equipment manufacturers).  The preamble consists of a cyclic prefix (to handle multipath interference) followed by an 800 μs sequence. In preamble formats 2 and 3, the sequence is repeated. The total length of the cyclic prefix and the sequence(s) determines how long it takes to transmit the preamble. Since the actual physical transmission occurs in units of sub-frames (1 ms), the remaining time determines how far away the UE can be without overlapping another UE's access attempt (the guard time). For further details, refer 3GPP TS 36.211 - Physical Channels and Modulation.

The operator typically must pick a preamble format to determine the coverage area desired. In the event of remote sites deployment, the length of the fiber to the remote cells must be considered as part of the cell radius (this includes Distributed Antenna Systems -DAS- ). Since the speed of electromagnetic waves over fiber is only two thirds of the speeds in free space, the total cell radius reduces to the values shown in the table below.

  • Hi Lauro

    Very informative , Thanks a lot.

    Eagerly waiting for Part-2 and Part-3.

  • Very informative.what about TD-LTE?

  • Hello Lauro,

    Could you elaborate a little more on the above calculations for remote sites and how you arrived at the reduced cell radius.

    There would appear to be a piece of information missing to understand the figures in the table. Would the reduced cell radius not be a function of fiber length and radio distance? Am i missing something?