LTE Air Interface Primer

It's good to see whitepapers coming out from different companies taking a closer look at LTE. Lots of interesting material can be found at Agilent's LTE Network Testing web page. I especially like the LTE (Air Interface) introduction webcast and the LTE System Overview whitepaper.

Although I am already aware of many things discussed in the paper, its always good to read about things from an author that looks at the topic from a different perspective. Here are a few of the things I found outstanding (for me personally) in the whitepaper:

Good Air Interface Graphics: The paper has some awesome graphics on how the physical channels map onto the different sub-carriers (or more precisely resource blocks). It's interesting to note that the control channels can take up to 30% of the cell capacity in case lots of devices require to be scheduled (e.g. Figure 23). That's quite a lot of capacity wasted for signaling. I guess we have to wait and see if in practice that much signaling capacity is really required.

Fractional Frequency Re-use: To improve cell edge performance the paper mentions the use of only a fraction of the sub-carriers to be broadcast at higher power levels. I've written about this quite some time ago and it's good to finally see some papers who are going into this direction as well.

BCCH: Broadcast once every 10ms (one frame) around the center frequency.

HARQ ACK/NACK: Contains intereresting details on where, when and how the acknowledgments are sent in uplink and downlink direction.