4G/LTE

  

 

 

 

Reference Signal - Downlink

 

Most of the channels (e.g, DPSCH, DPCCH, PBCH etc) is for carrying a special information (a sequence of bits) and they have some higher layer channel connected to them, but Reference Signal is a special signal that exists only at PHY layer. This is not for delivering any specific information. The purpose of this Reference Signal is to deliver the reference point for the downlink power.

 

When UE try to figure out DL power (i.e, the power of the signal from a eNode B), it measure the power of this reference signal and take it as downlink cell power.

 

These reference signal are carried by multiples of specific Resource Elements in each slots and the location of the resource elements are specifically determined by antenna configuration.

 

As LTE gets evolved into higher version, we are getting more and more reference signal which is mapped to a specific antenna port. And we are getting more and more confused as a result -:)

 

Following shows the reference signals supported by each 3GPP version.

 

3GPP

Reference Signal (Antenna Ports)

36.211 V8.9.0 (2010-01) - Section 6.10

 p0,p1,p2,p3,p4,p5

36 211 V9.1.0 (2010-04) - Section 6.10

 p0,p1,p2,p3,p4,p5,p6,p7,p8

36.211 V10.7.0 (2013-04) - Section 6.10

 p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p15,p16,p17,p18,p19,p20,p21,p22

36 211 V11.4.0 (2013-10) - Section 6.10

 p0,p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p15,p16,p17,p18,p19,p20,p21,p22

  

For the exact Resource Element locations of each reference signal, refer to following pages.

 

  • RS (Reference Signal) - Cell Specific (Antenna port 0,1,2,3)
  • RS (Reference Signal ) - MBSFN (Antenna Port 4)
  • RS (Reference Signal ) - UE Specific (Antenna Port 5,7,8,9,10)
  • RS (Reference Signal ) - Positioning (Antenna Port 6)
  • RS (Reference Signal ) - CSI (Antenna Port 15,16,17,18,19,20,21,22)

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