Thursday 25 March 2010

Home Relays for LTE-Advanced

If you look at the Home eNodeB (Femtocell) architecture, the HeNB is connected to its gateway which in turn is connected to MME/S-GW. There is a considerable amount of technology investment in this approach. The HeNB consists of complete protocol stack, the HeNB-GW is an expensive piece of equipment and there is lots of other things including the management software, etc.
Now in LTE-A, there is a concept of Relays which we have talked about. The Relays do not contain the complete stack (generally just L1 and L2). If capacity is not an issue but coverage, then we may be able to use Home Relays.

The backhaul for Femtocell is Internet whereas for Relay its generally the same Radio resources within the cell. I guess the main thing for Relay is the requirement of reasonably good channel (Line of sight maybe). Home Relays can use the Internet connection but rather than connection terminating in some kind of gateway, it can terminate at the actual eNB.

There are already many advanced antenna techniques that can handle the transmission and reception without much interference and maybe the SON algorithms may need some additional improvements.
The main thing is that if this technology becomes reality then it may cost less than $50 per Home relay and would become really a commonplace.


Charan Char said...

How the relays control interference and delay in the transmission. Is it for saving energy at eNB?

Zahid Ghadialy said...

Hi Charan, please see my old blog post and comment here

Unknown said...

Dear Zahid,
Is there any concept of indoor relays having multiple antennas in LTE-Advanced?

Zahid Ghadialy said...

Hi Soumendra, as far as I remember 2x2 MIMO is supported in Indoor relays. I am not sure though what purpose they may serve.

The backhual for Indoor relays will be Ethernet and there may be a limit on how much data rate the backhaul supports. So MIMO may not serve much purpose. The multipath may not provide much improvement in indoor environment anyway.

Orange had some evaluation paper here which may give you more insights.

Unknown said...

Hi Zahid,
Thanks for your timely suggestions. Actually, I am trying to simulate eNodeB->IndoorRelay->UE with Indoor relay having multiple receive antennas and one transmit antenna in order to get improved error performance. Please share your views in this matter.

Zahid Ghadialy said...

Hi Soumendra, I guess in that case the antennas are intended to increase reliability by using rx diversity which would be good.