Came across this interesting presentation from Airspan which their CTO Paul Senior delivered at Small Cells World Summit in May. Here they are suggesting that relays could be used used on the cell edge to backhaul small cells and hence improve throughput for a UE that is camped on small cell. Probably much easier to understand from the picture below.
This approach is similar to in-band backhaul that is used by other vendors. I gave an example of in-band backhaul from Parallel Wireless in my Rural coverage post here. The advantage of relays & in-band backhaul is that the small cells could be deployed easily and also moved/relocated later on as there is no limitation due to backhaul provision.
In an article from last year on ThinkSmallCell, Paul said:
The 3GPP standard includes a feature to support remote relays at the cell edge, which only needs power to rebroadcast the signal into poor coverage areas. However, this requires a separate protocol stack in the macrocell – something which not all vendors have implemented.
Instead, we've built a simple relay using a directional antenna to the macro which operates at a different frequency band, say 2.6GHz TD-LTE, and rebroadcasts at 1800MHz FDD-LTE. The antenna form factor and design enables much better utilisation of the link that when serving smartphones directly, using 64QAM rather than QPSK to achieve much higher throughput within the same spectrum and macrocell resources. The short range radio link to the end users also provides the potential for higher speeds and better service quality. It's a quick and effective solution for enterprise buildings at the edge of coverage.
The potential capacity of an LTE Relay isn't insignificant. If we used LTE with 256QAM, 8x8 MIMO we could see a consistent throughputs of 450Mbps.
I could also see this being useful in transport applications, such as for Connected Cars. We'll be releasing products later this year for vehicle based solutions at various frequency bands.
They did demo some of the products in SCWS2016, which can be seen in another ThinkSmallCell report here.
The Airspan presentation is as follows:
- Radio relay technologies in LTE-Advanced
- Mobile Relay Nodes (MRN) in Rel-12
- Small Cells for the 'Connected Car'
- Airspan squeeze high system performance from urban small cells - ThinkSmallCell