Small Cells Backhaul & Coordination

An interesting presentation from the Small Cells Backhaul Summit in June 2014. Time synchronization between Macro and Small cells are becoming very important for new features like eICIC, CoMP, etc. This presentation provides some insights into this.

MEF: LTE/LTE-A Small Cell Backhaul from Zahid Ghadialy

New types of HetNet's Cell coordination

Came across this HetNet Infographic from Ericsson here. They are proposing something interesting as can be seen in the picture above. From the infographic:

Macro for downlink, micro for uplink
In the imbalance area, the downlink signal from the macro is the strongest, because it transmits at a much higher power, whereas the uplink signal from the pico node is much stronger, because it is closer. This provides the user with significantly higher uplink speeds than would be possible with macro coverage alone.

So if we have a macro with an overlay of small cells then the Macro can be used for DL and Small Cells for UL. This scheme is a counterintuitive to what I would have thought. Since there is a higher requirement in DL as opposed to UL, the uplink could be received by Macro and the DL could be sent from pico node. The macro also has bigger antennas and can process weak signals from the UE.



Ericsson and the South Korean operator, SK Telecom recently also demonstrated 'Elastic Cell'. As per Telecom TV:

The telco has confirmed that Elastic Cell technology is based on the 3GPP Release 11 CoMP specification, but with improved scheduling, energy efficiency, and cost efficiency. SK Telecom says it has applied downlink CoMP since early 2012 and uplink CoMP in April 2014, and both technologies are proprietary technology. Because coordination between networks will still be very important in 5G technologies, SK Telecom expects that Elastic Cell will become a key enabler for 5G.

Another similar approach that is proposed by NTT Docomo is the 'Phantom Cell' concept as described here. Their proposal is to separate control and user planes. Macro used for signalling (C-plane) and Small cells in higher frequencies for data (U-plane)

Finally, we also have the SK Telecom's SUPER Cell concept and blogged here. There is a lot of cell splitting in this but again we have the main frequency (lower) being able to do both control and data while the higher frequency is only to do data. Sounds a bit like the Phantom Cell and 'New Carrier Type' as blogged here before.

Are there any other types of cell coordination being discussed. Do you have any opinion on them? Feel free to add comments.

The role of Small Cells, CoMP and Massive MIMO in 5G

Embedded below is a recent paper from IEEE Communications Magazine on the role of various techniques in 5G. The main focus is achieving higher spectral efficiency. From the paper: "From a high-level perspective, there are three main contributors to reaching higher spectral efficiency: advanced interference mitigation, small cells for densification of the network nodes, and massive multiple-input multiple-output (MIMO), that is, a significant increase in the number of antennas at the base station and potentially also at the terminal."