Friday, 31 October 2014

Non-ideal backhaul for Small Cells

Recently I came across this Linkedin discussion on What is "non-ideal backhaul" so I thought it may be worth adding it to the blog. The simplest of explanation can be seen from the picture above that is extracted from 3GPP TR 36.932.

An ideal backhaul is defined as latency less than 2.5 microseconds and a throughput of upto 10Gbps. All other types of backhaul is non-ideal.

Another way of putting this is: If you look at the Release 12 study and technical report on Small Cell Enhancements, it is regarded as a backhaul that cannot carry a RRH to eNodeB link, which in turn has been interpreted as not meeting CPRI round trip and bandwidth requirements (via Kit Kilgour)

If you know anything additional, please feel free to add it in comments.


  1. Rajesh Mishra (via Small Cells World Series Linkedin group)3 November 2014 at 11:07

    Really curious about 10Gbps "Backhaul" requirements? Don't know if have as many CA combinations to add up to 10Gbps "Backhaul" requirements for an eNodeB.

  2. David Chambers (via Small Cells World Series Linkedin group)3 November 2014 at 11:08

    This is the crux of the debate: If you use a small cell, then you only require limited backhaul bandwidth for the user data/signalling. If you use Cloud RAN/Remote Radio Heads then you need the full compressed radio signal using CPRI (up to 3.5Gbps per sector). Analog DAS may need even more. So sites with a few sectors and/or carrier frequencies could use anything up to 20Gbps. That generally means (dark) fibre, whereas a small cell can be connected using copper or one of the many wireless backhaul alternatives via standard Ethernet. The term Fronthaul is often used to distinguish this much higher CPRI data rate to the remote radio heads.