ro cell on the left (it shows only the top of the mast) and a small cell on the right (outside a building in Bangalore). The macro cell has three clear sectors (120 degrees each) and the small cell has a GNSS antenna attached to it. Figure 11-2 Macro Cell Versus Small Cell (Sources: left, © Justin Smith / Wikimedia Com- mons, CC-BY-SA-2.5; right, © Rohanmkth / Wikimedia Commons, CC-BY-SA-4.0) The correct approach to providing timing for these different categories should become clear when reading their main features. These two broad categories need to be handled differently, certainly from the following aspects: Ability to deploy a GNSS-based solution Level of holdover performance (oscillator quality) Resilience to failure and need for backup or redundancy Transport options toward the back-haul network (and to neighboring sites) A large macro cell (in North America, anyway) might already have GPS equipment with a good stable oscillator, SO providing any form of timing over the transport or some redundancy scheme might be unwarranted. It already has a source of frequency, phase, and time with good holdover performance, and additional effort might not be required. On the other hand, the small cell has none of those advantages. If small cells are all located indoors, that would make it very difficult to provide GNSS receivers for every small cell in that facility. For something like a campus or shopping center, for example, it might make more sense to deploy a GNSS receiver with a PTP grandmaster (GM) in a rooftop location and carry phase/time to every small cell over the local LAN cable infrastructure by using PTP. For resilience, losing the function of a single small cell in a shopping center might have limited ef- fect. Frequently, there is overlapping coverage from other cells, and an outside macro cell can also cover any dead spots. For operators, it might not be worth trying to provide expensive redundancy for what are relatively cheap devices if enough of them are deployed, and it is the same for timing. Of co