OK, what the hell is a small cell? Well, let me tell you about small cells. It’s like putting the cell site where the people are, I mean right where the people using the most data. Suddenly you have a cell that can service a group of people with little RF loss and high data throughput. This is a great thing for carriers because it relieves the macro from the loading it would have from one area in its larger coverage area. That is the goal of the small cell, to alleviate the loading and add coverage. I will concentrate on the outdoor small cells for this article but the indoor may be very similar, just less up front work.
So putting a small cell in should be easy, right? I mean if any of you worked with Wi-Fi you would think you can just pop up an access point and you have an instant hot spot. Well, there is so much more to it than that. The carriers will need to do some work up front is they are to put it in their system. They need to do the RF design, loading study, and coverage analysis. They will probably study the analytics to see where the need is based on coverage and macro cell loading, (data and voice). This is prior to placing the small cells in the macro coverage area. They will look at each sector of a Macro site.
The other challenge is putting the backhaul in. It usually will be fiber, about 10 to 100Gbps backhaul provided to the router connected to the small cell. This is usually a Service Aggregate Router, (SAR). Backhaul quality is everything because you have to make sure you have quality of service. Here is where the LTE small cells have a huge advantage because they have a complete IP backbone, unlike most 3G stuff out there, LTE will be a cleaner deployment. All this is done before they decide to deploy anything.
So mounting the unit will not be too hard, but the connection of the backhaul will require fiber skills. They may have wireless backhaul in some areas, if they connect from the wireless backhaul to the SAR it will be using a fiber jumper. Fiber will be the key to most small cell backhaul connections. The one exception may be if the cable companies step up with a cable backhaul for small cells, they call this Data Over Cable Interface Specification, (DOCSIS), which should be a game changer if it becomes mainstream. Then you could use a standard cable connection for backhaul. This may or may not work because carriers seem to like a dedicated connection back to their core or to one of their cell sites. This is a dedicated connection that would give them security and complete control. It’s what most of them want to do. They don’t just tie into an internet connection like a Wi-Fi connection would. It’s just not that easy at this time. If you’re interested in LTE backhaul, there is a good overview at http://lteuniversity.com/get_trained/expert_opinion1/b/skrishnamurthy/archive/2013/04/01/why-ethernet-backhaul.aspx to explain in more detail.
So let’s look at what we’ve done, we’ve completed the engineering, defined the spots where we wanted it. We then narrowed the spot by finding a mounting location, a pole or a building top, then we found a mounting location that has a fiber connection near it, (fiber is not everywhere), now we finally have the exact location to mount it. Then we have to get a lease, this is all part of site acquisition! We need to work out all of those headaches. If you are not familiar, you don’t just go out and mount it to a pole. You need to find out who has rights to the pole or building, who you lease it through. Then you may or may not need to do a structural analysis on the mounting asset. You will need to do a site design drawing for the documentation prior to the mounting of the asset. What about permits? The local municipality or city wants to take their cut and they want to know what is mounted where. So you will need to make sure all the permitting is completed, this usually slows down the process even more and cost money because you need to file paperwork and often need to hand deliver the documentation.
OK, location found, fiber nearby, mounting asset identified, leasing completed, permitting completed, now we can mount and move ahead, right? OK, now we need to follow the engineering, install the unit, connect the fiber, power to the unit. Did you say power? Did anyone order power? This is something else that needs to be taken care of, power at the pole. So now, at a pole we need fiber and power. Both have a long lead time.
OK, pole, permitting, lease, power, fiber, so now we can mount and connect it up. Then we’re off to the races. Well, it is mounted to the pole so we are good there. We connected the backhaul to the SAR, we are good there. We now power it up and it should work, right? Make sure the antennas are facing the proper direction and the tilt is set up properly. Now you need to make sure it is provisioned properly, that means that the SAR has to be integrated, then the small cell has to be integrated, then the carrier will want to make a test call and they may or may not want to optimize it with someone doing a walk test. Remember, if the cell has any problems it could create more problems with self interference. The engineering has to take that into consideration. Self interference is taken very seriously because it will create dead spots.
Once the small cell is up and running, life is good in that area, loading is off the macro and on the small cell. The carriers plan to put 10s of thousands of these in. I believe that if the FCC allows more bandwidth to be freed up for LTE, this will be the way that utilities will access their fixed networks. Public Safety already is carving out their chunk of LTE bandwidth. I think that they will rely heavily on small cells because they need coverage in specific areas. Let’s face it, LTE and small cells will be an amazing thing as the world of data takes over. Video will not be just for entertainment, it will be the requirement both ways, video streaming up to the network and down to a device.
OK, now I gave you a background, how does it affect the field worker? Well, you may need to be certified to mount the small cell by the OEM. Remember that the warranty will be affected if you mess something up. Also, this is going to have intricacies that may be affected by how you mount it. Antenna direction, fiber skills, and power connection could all play into this. The Power Distribution Unit (PDU) may be mounted at a different location to power the SAR and Small Cell. You need to know what you are doing to make the connections. It will take skills. Chances are good that you will need to make a test call for the integration phase, provisioning, to be completed. You may need to program the SAR by connecting your laptop to it and uploading a specific configuration file. You need skills! This isn’t Wi-Fi, it’s carrier grade equipment. If you do tower work you know the difference.
I plan to do more on small cells in the future. This is something I have been working on and I have more information to share.
Let me know what you’re struggling with out there in the field. I would like to write about something that could help. Let me know what you think by leaving a comment or hitting me up on Facebook or reach out to me on LinkedIn at www.linkedin.com/in/wadesarver/! I am looking for tower pictures on Facebook page! I am working on a new book, an aid for the field worker and I plan to have a new website ready soon. I have been very busy on other projects but I think that it should happen soon.
Hey, I talk about learning fiber training and I see that JDSU has free webinars on fiber, go their website here and see if you can learn more about fiber! The webinars are free!
To learn more about LTE and Small Cells;