Blog – Verizon’s 5G and a video by R&S

A couple of days ago, I had a post on the status of 5G and realistic timelines. A lot of politics is involved concerning the dates and when to do what but few technical details have so far emerged without looking deeply into the meeting minutes. Zahid Ghadialy over at the 3G4G blog, however, has now dug up some interesting technical details.

Personally I found the Rohde and Schwarz video he links to very interesting. It explains in some detail in 7 minutes what Verizon has in mind for their early 5G non-mobile wireless last-mile connectivity network. In essence, Verizon wants to use a modified TD-LTE air interface for the 28 GHz band with up to 8 carriers with a bandwidth of up to 100 MHz each. So in total they could combine up to 800 MHz which is an interesting comparison to the 50 to 60 MHz typically aggregated today by high quality networks (or even only 10 MHz in some rural deployments). That sounds a lot and it probably is. However, it should be kept in mind that at 28 GHz and longer distances, there will probably be only a single data stream per device and conservative modulation and coding.

In addition, instead of using OFDM with a 15 kHz subcarrier spacing they are going for 75 kHz because, from what I understand, they want to use massive MIMO on the base station side for beamforming so there’s less multipath fading that requires narrower carriers. On the MAC layer, modifications are made to TD-LTE to quickly adapt to changing uplink and downlink traffic ratios. Again, beamforming helps to isolate different cells and beams from each other so simultaneous uplink and downlink transmissions have a limited effect on each other.

The R&S video also mentions that the uplink will also be in the 28 GHz band. Zahid and the EETimes, on the other hand note that the Qualcomm X50 chipset for mobile devices also supports simultaneous transmissions in the 28 GHz band with a lower frequency band which is then used for signaling. This not mentioned in the video so I guess this is more applicable for Korea and Japan where network operators want to roll out a mobile 26 GHz pre-5G standardized network.