Tuesday 1 July 2014

3GPP Definitions of Small Cells

While the Small Cell Forum defines the different types of Small cells clearly and these Small Cells can be said to contain the complete/partial functionality of the eNodeB, 3GPP definitions of Small Cells can be a bit fuzzy sometimes.

Generally, in the 3GPP documentation, there is a reference to Femtocells and Picocells. Femtocells are Small Cells that are defined as Closed Access (see my old post here) by 3GPP. The open access small cells are referred to as Picocells. Sometimes remote radio heads (RRH's) are also referred to as Small cells, open access type.

Relays, even though not referred to as Small Cells by 3GPP, is also referred to as Small Cells by some people.

Do you know of anything else?


  1. Atul Deshpande (via Small Cells World Series Linkedin group)18 July 2014 at 10:37

    Hi Zahid,

    I have been recently going through some HeNB 3GPP Specs and found no such mention.

    A Femtocell (now termed as Small Cell), can have 3 different access methods including OSG, CSG or both.

    What I found that the TS doesn't mention term as Pico or Femto, while always refer to as HeNB or eHeNB or something of that sort in purely technical wording.

    I'm curious to know more about the distinction you made between Femto & Pico in terms of CSG & OSG in your blog. Can you share more details pls?

    Thank you.

  2. Hi Atul,

    You are correct, the core specs for HNB/HeNB do not use the terms Femtocells and Picocells. Other specs, for example that talks about eICIC mention Femto and Pico. TS36.300 is one such. In fact I noticed in the latest one they refer to CSG scenario (instead of Femto scenario) and Pico Scenario. I have seen references of Femto in some 3GPP TR's, etc. in the past to refer to as CSG.

    I have also blogged about the Open, Closed and Hybrid access cells here: http://smallcells.3g4g.co.uk/2014/05/open-closed-and-hybrid-access-small.html

  3. Technically, the 'picocell' concept was introduced as a power class into 2G only, but the term is now more widely used for an intermediate low power node that has higher power than a femtocell. HNB refers to a combination of architecture (Iuh) and power class (HNB power class is below Local Area Class in Tx power, requires more adjacent rejection but fewer high speed and long ranges test cases needed). However, not that the Iuh architecture has been and is easily re-used for higher power cells, including rural and remote access. A HeNB also has its own power class in a similar way to HNB, but re-uses the same S1 protocol to the core as a macro eNodeB, with one of the few difference being that a HeNB consists of only one cell and has a slightly different cell Id format as a result that enables efficient use of the space of Cell Ids. The concepts of Hybrid and Closed access cells applies to HeNB and HNB only - not to the macro layer.

  4. Thanks Kit, I should have clarified that Hybrid and Closed cells concept doesn't apply to macro layer.